Sample records for formulations phase separation

  1. Development and validation of a reversed-phase HPLC method for separation and simultaneous determination of process-related substances of mirtazapine in bulk drugs and formulations. (United States)

    Rao, R Nageswara; Raju, A Narasa


    A simple and rapid reversed-phase high-performance liquid chromatographic method has been developed for the separation and simultaneous determination of related substances of mirtazapine in bulk drugs and pharmaceutical formulations. Six impurities, including one degradation product of mirtazapine, have been separated on a BDS Hypersil (4.6 x 250 mm; particle size 5 microm) column with a mobile phase consisting of 0.3% triethylamine (pH 3.0)-acetonitrile (78:22 v/v) eluted in an isocratic mode and monitored with a photo diode array detector at 215 nm. The chromatographic behavior of all the analytes was studied under variable compositions of different solvent systems, temperatures, buffer concentrations, and pH values. The method was validated in terms of accuracy, precision, and linearity. The inter- and intra-day assay precision was found to be method was successfully applied to the analysis of commercial formulations and the recoveries of mirtazapine were in the range of 99.38-100.73% with method is useful not only for rapid evaluation of the purity of mirtazapine, but also for the simultaneous determination of related substances in bulk drugs and pharmaceutical formulations.

  2. diffusive phase separation

    Directory of Open Access Journals (Sweden)

    Nobuyuki Kenmochi


    w is constrained to have double obstacles σ*≤w≤σ* (i.e., σ* and σ* are the threshold values of w. The objective of this paper is to discuss the semigroup {S(t} associated with the phase separation model, and construct its global attractor.

  3. Phase separation micro molding

    NARCIS (Netherlands)

    Vogelaar, Laura


    The research described in this thesis concerns the development of a new microfabrication method, Phase Separation Micro Molding (PSμM). While microfabrication is still best known from semiconductor industry, where it is used to integrate electrical components on a chip, the scope has immensely expan

  4. Microgravity Passive Phase Separator (United States)

    Paragano, Matthew; Indoe, William; Darmetko, Jeffrey


    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

  5. Physico-chemical separation process of nanoparticles in cosmetic formulations (United States)

    Retamal Marín, R. R.; Babick, F.; Stintz, M.


    Understanding the world of nanoparticles, especially their interactions with the environment, begins with their correct detection and successive quantification. To achieve this purpose, one needs to perform correctly developed standard operating procedures (SOPs). Furthermore, the study of nanoparticles frequently requires their characterisation in complex media (e.g. in cosmetic formulations). In this study, a set of sample preparation procedures for the detection and extraction of NMs in emulsion-based formulations is proposed and their performance for model and real-life products is discussed. A separation or extraction of lipid phases is achieved by means of organic solvents. The polarity of the lipid phases is decisive for selecting an optimum solvent. The use of the Hansen Solubility Parameters (HSP) may clearly support this decision.

  6. The Electromagnetic Duality Formulation of Geometric Phases (United States)

    Zhang, Yuchao; Li, Kang


    This paper focuses on the electromagnetic(EM) duality formulation of geometric phases of Aharonov-Bohm(A-B) effect and Aharonov-Casher(A-C) effect. Through the two four-vector potential formulation of electromagnetic theory, we construct a EM duality formulation for both A-B effect and A-C effect. The He-McKellar-Wilkens(HMW) effect is included as a EM duality counterpart of the A-C effect, and also the EM duality counterpart of the A-B effect is also predicted.

  7. Formulation and picture of quantum phase

    Institute of Scientific and Technical Information of China (English)

    YAO ZhiXin; ZHONG JianWei; PAN BaiLiang


    Based on the concept of classical phase, we formulate a new explanation for the quantum phase from the quantum mechanical point of view. The quantum phase is the canonically conjugate variable of an angular momentum operator, which corresponds to the angular position φ in an actual physical space with a classical reference frame, but it takes a complex exponential form e~(iφ)-cosφ+i sinφin the abstract Hilbert space of a quantum reference frame. This formulation is simply the famous Euler formula in a complex number field. In particular, when φ= π/2, the correlative quantum phase is a unitary pure imaginary number e~(iπ/2)=cos(π/2)+i sin(π/2) = i. By using a photon state-vector function that is the general solution of photon Schrodinger equation and can completely describe a photon's behavior, we discuss the relationship between the angular momentum of a photon and the phase of the photon; we also analyze the intrinsic relationship between the macroscopic light wave phase and the microscopic photon phase.

  8. Formulation and picture of quantum phase

    Institute of Scientific and Technical Information of China (English)


    Based on the concept of classical phase,we formulate a new explanation for the quantum phase from the quantum mechanical point of view. The quantum phase is the canonically conjugate variable of an angular momentum operator,which corresponds to the angular position θ in an actual physical space with a classical reference frame,but it takes a complex exponential form eiθ≡cosθ +i sinθ in the abstract Hilbert space of a quantum reference frame. This formulation is simply the famous Euler formula in a complex number field. In particular,when θ = π/2,the correlative quantum phase is a unitary pure imaginary number eiπ/2 ≡cos(π/2)+i sin(π/2) ≡ i. By using a photon state-vector function that is the general solution of photon Schrdinger equation and can completely describe a photon’s behavior,we discuss the relationship between the angular momentum of a photon and the phase of the photon; we also analyze the intrinsic relationship between the macroscopic light wave phase and the microscopic photon phase.

  9. Motility-Induced Phase Separation (United States)

    Cates, Michael E.; Tailleur, Julien


    Self-propelled particles include both self-phoretic synthetic colloids and various microorganisms. By continually consuming energy, they bypass the laws of equilibrium thermodynamics. These laws enforce the Boltzmann distribution in thermal equilibrium: The steady state is then independent of kinetic parameters. In contrast, self-propelled particles tend to accumulate where they move more slowly. They may also slow down at high density for either biochemical or steric reasons. This creates positive feedback, which can lead to motility-induced phase separation (MIPS) between dense and dilute fluid phases. At leading order in gradients, a mapping relates variable-speed, self-propelled particles to passive particles with attractions. This deep link to equilibrium phase separation is confirmed by simulations but generally breaks down at higher order in gradients: New effects, with no equilibrium counterpart, then emerge. We give a selective overview of the fast-developing field of MIPS, focusing on theory and simulation but including a brief speculative survey of its experimental implications.

  10. Viscoelastic Phase Separation of Protein Solutions (United States)

    Tanaka, Hajime; Nishikawa, Yuya


    In addition to the known behavior of normal phase separation and gelation, we report novel phase-separation behavior of protein solutions as their intermediate case. A network structure of the protein-rich phase may be formed even if it is the minority phase, contrary to the conventional wisdom. This behavior is characteristic of viscoelastic phase separation found in polymer solutions. This kinetic pathway may play crucial roles in the complex phase ordering of protein solutions, in particular, protein network formation in biological systems and foods.

  11. Binary Colloidal Alloy Test-5: Phase Separation (United States)

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


    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.

  12. Arrested segregative phase separation in capillary tubes

    NARCIS (Netherlands)

    Tromp, R. Hans; Lindhoud, Saskia


    Phase separation in a capillary tube with one of the phases fully wetting the capillary wall is arrested when the typical size of the phase domains reaches the value of the diameter of the tube. The arrested state consists of an alternating sequence of concave-capped and convex-capped cylindrical

  13. Phase separator safety valve blow-off.

    CERN Multimedia

    G. Perinic


    The fast discharge of the CMS solenoid leads to a pressure rise in the phase separator. On August 28th, a fast discharge was triggered at a current level of 19.1 kA. The pressure in the phase separator increased up to the set pressure of the safety valve and some helium was discharged. In consequence of this and prevoious similar observations the liquid helium level in the phase separator has been reduced from 60% to 50% and later to 45% in order to reduce the helium inventory in the magnet.

  14. Phase Separation Dynamics in Isotropic Ion-Intercalation Particles

    CERN Document Server

    Zeng, Yi


    Lithium-ion batteries exhibit complex nonlinear dynamics, resulting from diffusion and phase transformations coupled to ion intercalation reactions. Using the recently developed Cahn-Hilliard reaction (CHR) theory, we investigate a simple mathematical model of ion intercalation in a spherical solid nanoparticle, which predicts transitions from solid-solution radial diffusion to two-phase shrinking-core dynamics. This general approach extends previous Li-ion battery models, which either neglect phase separation or postulate a spherical shrinking-core phase boundary, by predicting phase separation only under appropriate circumstances. The effect of the applied current is captured by generalized Butler-Volmer kinetics, formulated in terms of diffusional chemical potentials, and the model consistently links the evolving concentration profile to the battery voltage. We examine sources of charge/discharge asymmetry, such as asymmetric charge transfer and surface "wetting" by ions within the solid, which can lead to...

  15. Polymer solution phase separation: Microgravity simulation (United States)

    Cerny, Lawrence C.; Sutter, James K.


    In many multicomponent systems, a transition from a single phase of uniform composition to a multiphase state with separated regions of different composition can be induced by changes in temperature and shear. The density difference between the phase and thermal and/or shear gradients within the system results in buoyancy driven convection. These differences affect kinetics of the phase separation if the system has a sufficiently low viscosity. This investigation presents more preliminary developments of a theoretical model in order to describe effects of the buoyancy driven convection in phase separation kinetics. Polymer solutions were employed as model systems because of the ease with which density differences can be systematically varied and because of the importance of phase separation in the processing and properties of polymeric materials. The results indicate that the kinetics of the phase separation can be performed viscometrically using laser light scattering as a principle means of following the process quantitatively. Isopycnic polymer solutions were used to determine the viscosity and density difference limits for polymer phase separation.

  16. Wetting and phase separation at surfaces

    Indian Academy of Sciences (India)

    Sanjay Puri; Kurt Binder


    We study the problem of surface-directed spinodal decomposition, viz., the dynamical interplay of wetting and phase separation at surfaces. In particular, we focus on the kinetics of wetting-layer growth in a semi-infinite geometry for arbitrary surface potentials and mixture compositions. We also present representative results for phase separation in confined geometries, e.g., cylindrical pores, thin films, etc.

  17. Gas-Liquid Flows and Phase Separation (United States)

    McQuillen, John


    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 .

  18. Phase separation in an ionomer glass

    DEFF Research Database (Denmark)

    Pedersen, Malene Thostrup; Tian, K.V.; Dobó-Nagy, C.


    conclusively determined. In this work, we identify these phases by performing differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses on both the as-received glass and heat-treated samples. We detected three glass transitions in the as-received G338 glass during DSC upscaning, implying...... amorphous phases in G388 are Ca/Na-Al-Si-O, Ca-Al-F and Ca-P-O-F phases, respectively. However, the exact chemical compositions of the three phases still require further exploration. The results of this work are important for understanding the impact of phase separation within ionomer glasses on the setting...

  19. Separation of magnetic phases in alloys

    Energy Technology Data Exchange (ETDEWEB)

    Takacs, J. [Department of Engineering Science, University of Oxford, 5. Pound Close, Yarnton, Oxon OX5 1QG, Oxford (United Kingdom)], E-mail:; Meszaros, I. [Department of Materials Science and Technology, Budapest University of Technology and Economics, Budapest (Hungary)


    In this paper we present a study of the separation of phases in multi-phase alloys. The proposed technique is based on the hyperbolic model of magnetization. By using this model it is possible to decompose the magnetic phases of alloys and determine their magnetic properties separately. Experimental verification was carried out on a transformer-like setup, constructed from layered samples representing the various magnetic phases. The samples were constructed from elements of strongly different magnetic properties. The results given by the model are in an excellent agreement with the experimental results, giving justification for the proposed method of decomposition. The proposed method is the first step towards the recognition and the separation of magnetic constituencies of different magnetic properties in an alloy by analytical means.

  20. Electronic phase separation and high temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kivelson, S.A. [Univ. of California, Los Angeles, CA (United States). Dept. of Physics; Emery, V.J. [Brookhaven National Lab., Upton, NY (United States)


    The authors review the extensive evidence from model calculations that neutral holes in an antiferromagnet separate into hole-rich and hole-poor phases. All known solvable limits of models of holes in a Heisenberg antiferromagnet exhibit this behavior. The authors show that when the phase separation is frustrated by the introduction of long-range Coulomb interactions, the typical consequence is either a modulated (charge density wave) state or a superconducting phase. The authors then review some of the strong experimental evidence supporting an electronically-driven phase separation of the holes in the cuprate superconductors and the related Ni oxides. Finally, the authors argue that frustrated phase separation in these materials can account for many of the anomalous normal state properties of the high temperature superconductors and provide the mechanism of superconductivity. In particular, it is shown that the T-linear resistivity of the normal state is a paraconductivity associated with a novel composite pairing, although the ordered superconducting state is more conventional.

  1. Dispersing and Separating Carbon Nanotubes with Novel Surfactant Formulations (United States)


    regions in the outer region of the complex. Following DGU, the buoyant density of the separated SWNTs is measured directly, and the SWNT chirality ...bioimaging, and drug delivery. Results and Discussion DGU-based separations of arc discharge grown SWNTs were performed with Pluronic block...17 Specific Chiralities Using Helical Assemblies of Flavin Mononucleotide. Nature Nanotech. 2008, 3, 356-362. 23. Green, A. A.; Hersam, M. C

  2. Simualting the Phase Separated rp-ash (United States)

    Caplan, Matthew; Horowitz, Chuck; Berry, Donald


    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.

  3. Phase separation sections. Passing with minimum constraints

    Energy Technology Data Exchange (ETDEWEB)

    Bastian, Arnaud; Courtois, Christian; Machet, Alexandre [SNCF, Direction de l' Ingenierie, La Plaine Saint Denis (France). Dept. des Installations Fixes de Traction Electrique


    Phase separation sections in AC 50 Hz electrified railway networks are critical. As a matter of fact, a lack of respect by the engine driver with regard to the signalling could lead to damage the infrastructure integrity. The regularity of the traffic could be strongly impacted in such a case. Therefore, SNCF Fixed Installation for Electric Traction has worked for years to improve the reliability of these specific equipments with many solutions based on infrastructure and/or rolling stock equipment. Some of these solutions are presented. (orig.)

  4. A Rapid Reversed-Phase HPLC Method for Analysis of Trans-Resveratrol in PLGA Nanoparticulate Formulation


    Singh, Gurinder; Pai, Roopa S.


    A rapid reversed-phase high performance liquid chromatography (RP-HPLC) method was developed for the determination of trans-resveratrol (t-RVT) in PLGA nanoparticle formulation. A new formulation of t-RVT loaded PLGA nanoparticles (NPs) with potential stealth properties was prepared by nanoprecipitation method in our laboratory. The desired chromatographic separation was achieved on a Phenomenex C18 column under isocratic conditions using UV detection at 306 nm. The optimized mobile phase con...

  5. An analytical formulation for phase noise in MEMS oscillators. (United States)

    Agrawal, Deepak; Seshia, Ashwin


    In recent years, there has been much interest in the design of low-noise MEMS oscillators. This paper presents a new analytical formulation for noise in a MEMS oscillator encompassing essential resonator and amplifier nonlinearities. The analytical expression for oscillator noise is derived by solving a second-order nonlinear stochastic differential equation. This approach is applied to noise modeling of an electrostatically addressed MEMS resonator-based square-wave oscillator in which the resonator and oscillator circuit nonlinearities are integrated into a single modeling framework. By considering the resulting amplitude and phase relations, we derive additional noise terms resulting from resonator nonlinearities. The phase diffusion of an oscillator is studied and the phase diffusion coefficient is proposed as a metric for noise optimization. The proposed nonlinear phase noise model provides analytical insight into the underlying physics and a pathway toward the design optimization for low-noise MEMS oscillators.

  6. Phase separation coupled with damage processes analysis of phase field models in elastic media

    CERN Document Server

    Heinemann, Christian


    The authors explore a unifying model which couples phase separation and damage processes in a system of partial differential equations. The model has technological applications to solder materials where interactions of both phenomena have been observed and cannot be neglected for a realistic description. The equations are derived in a thermodynamically consistent framework and suitable weak formulations for various types of this coupled system are presented. In the main part, existence of weak solutions is proven and degenerate limits are investigated. Contents Modeling of Phase Separation and Damage Processes Notion of Weak Solutions Existence of Weak Solutions Degenerate Limit Target Groups Researchers, academics and scholars in the field of (applied) mathematics Material scientists in the field of modeling damaging processes The Authors Christian Heinemann earned his doctoral degree at the Humboldt-Universität zu Berlin under the supervision of Prof. Dr. Jürgen Sprekels and Dr. Christiane Kraus. He is a ...

  7. Development of novel solid-phase protein formulations (United States)

    Montalvo Ortiz, Brenda Liz

    Proteins are the next-generation drugs for the treatment of several diseases. However, the number of protein drugs is still limited due to the physical or chemical instability of proteins during processing, formulation, storage, and delivery. The formulation of proteins at the solid state has advantages over liquid state, such as improved stability during long-term storage and delivery and decreases transportation costs. In this dissertation, we developed new solid-phase protein formulations in which the integrity of the protein was not compromised. The long term goal of this research was to use these protein formulations to improve protein stability in drug delivery devices, such as poly(lactic-co-glycolic) acid (PLGA). The first solid-phase protein formulation developed in this investigation was named "glassification". We proposed glassification as an alternative protein dehydration technique to the common used one, lyophilization, because this last method involves a series of steps which are detrimental to protein structure and stability. The glassification method consisted on protein dehydration by the use of organic solvents. As a result of the glassification process a small (micrometer size range) protein solid bead was obtained. The proteins used to study the glassification process were lysozyme (LYS), alpha-chymotrypsin (CHYMO) and horseradish peroxidase (HRP). These studies revealed that the glassification process itself did not alter protein structure and the activity was preserved. Ethyl acetate was the most effective organic solvent for protein glassification because it led to the highest protein residual activity, no insoluble aggregate formation and is a relatively non-toxic solvent, which allow the incorporation of these protein microparticles in PLGA microspheres. The incorporation of spherical HRP microparticles into PLGA microspheres resulted in superior properties when compared with encapsulated lyophilized HRP powder, such as improved release

  8. Simulation of phase separation in quiescent and sheared liquids

    NARCIS (Netherlands)

    Thakre, Amol Kumar


    In this thesis we report on molecular dynamics simulations of phase separation of simple and complex binary liquids in sheared and non-sheared systems. The separation of milk into liquid whey and solid curd is a very common example of phase separation observed in daily life. The phenomenon finds its

  9. A mechanical model for phase-separation in debris flow

    CERN Document Server

    Pudasaini, Shiva P


    Understanding the physics of phase-separation between solid and fluid phases as a mixture mass moves down slope is a long-standing challenge. Here, we propose an extension of the two phase mass flow model (Pudasaini, 2012) by including a new mechanism, called separation-flux, that leads to strong phase-separation in avalanche and debris flows while balancing the enhanced solid flux with the reduced fluid flux. The separation flux mechanism is capable of describing the dynamically evolving phase-separation and levee formation in a multi-phase, geometrically three-dimensional debris flow. These are often observed phenomena in natural debris flows and industrial processes that involve the transportation of particulate solid-fluid mixture material. The novel separation-flux model includes several dominant physical and mechanical aspects such as pressure gradients, volume fractions of solid and fluid phases and their gradients, shear-rates, flow depth, material friction, viscosity, material densities, topographic ...

  10. A Gibbs Formulation for Reactive Materials with Phase Change (United States)

    Stewart, D. Scott


    A large class of applications have pure, condensed phase constituents that come into contact, chemically react and simultaneously undergo phase change. Phase change in a given molecular material has often been considered to be separate from chemical reaction. Continuum modelers of phase change often use a phase field model whereby an indicator function is allowed to change from one value to another in regions of phase change, governed by evolutionary (Ginzburg-Landau) equations, whereas classic chemical kinetics literally count species concentrations and derive kinetics evolution equations based on species mass transport. We argue the latter is fundamental and is the same as the former, if all species, phase or chemical are treated as distinct chemical species. We pose a self-consistent continuum, thermo-mechanical model to account for significant energetic quantities with correct molecular and continuum limits in the mixture. A single stress tensor, and a single temperature is assumed for the mixture with specified Gibbs potentials for all relevant species, and interaction energies. We discuss recent examples of complex reactive material modeling, drawn from thermitic and propellant combustion that use this new model. DSS supported by DTRA, ONR and AFOSR.

  11. Polymerization- and solvent-induced phase separation in hydrophilic-rich dentin adhesive mimic. (United States)

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


    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.

  12. Spin Filtering in Epitaxial Spinel Films with Nanoscale Phase Separation

    KAUST Repository

    Li, Peng


    The coexistence of ferromagnetic metallic phase and antiferromagnetic insulating phase in nanoscaled inhomogeneous perovskite oxides accounts for the colossal magnetoresistance. Although the model of spin-polarized electron transport across antiphase boundaries has been commonly employed to account for large magnetoresistance (MR) in ferrites, the magnetic anomalies, the two magnetic phases and enhanced molecular moment, are still unresolved. We observed a sizable MR in epitaxial spinel films (NiCo2O4-δ) that is much larger than that commonly observed in spinel ferrites. Detailed analysis reveals that this MR can be attributed to phase separation, in which the perfect ferrimagnetic metallic phase and ferrimagnetic insulating phase coexist. The magnetic insulating phase plays an important role in spin filtering in these phase separated spinel oxides, leading to a sizable MR effect. A spin filtering model based on Zeeman effect and direct tunneling is developed to account for MR of the phase separated films.

  13. Strain phase separation: Formation of ferroelastic domain structures (United States)

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


    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.

  14. Spin Filtering in Epitaxial Spinel Films with Nanoscale Phase Separation. (United States)

    Li, Peng; Xia, Chuan; Li, Jun; Zhu, Zhiyong; Wen, Yan; Zhang, Qiang; Zhang, Junwei; Peng, Yong; Alshareef, Husam N; Zhang, Xixiang


    The coexistence of ferromagnetic metallic phase and antiferromagnetic insulating phase in nanoscaled inhomogeneous perovskite oxides accounts for the colossal magnetoresistance. Although the model of spin-polarized electron transport across antiphase boundaries has been commonly employed to account for large magnetoresistance (MR) in ferrites, the magnetic anomalies, the two magnetic phases and enhanced molecular moment, are still unresolved. We observed a sizable MR in epitaxial spinel films (NiCo2O4-δ) that is much larger than that commonly observed in spinel ferrites. Detailed analysis reveals that this MR can be attributed to phase separation, in which the perfect ferrimagnetic metallic phase and ferrimagnetic insulating phase coexist. The magnetic insulating phase plays an important role in spin filtering in these phase separated spinel oxides, leading to a sizable MR effect. A spin filtering model based on Zeeman effect and direct tunneling is developed to account for MR of the phase separated films.

  15. Control of structure formation in phase-separating systems

    NARCIS (Netherlands)

    Singh, A.; Mukherjee, A.; Vermeulen, H.M.; Barkema, G.T.; Puri, S.


    In this paper, we study the evolution of phase-separating binary mixtures which are subjected to alternate cooling and heating cycles. An initially homogeneous mixture is rapidly quenched to a temperature T1 phase separation for a whil

  16. Phase-separation transitions in asymmetric lipid bilayers

    CERN Document Server

    Shimobayashi, Shunsuke F; Taniguchi, Takashi


    Morphological transitions of phase separation associated with the asymmetry of lipid composition were investigated using micrometer-sized vesicles of lipid bilayers made from a lipid mixture. The complete macro-phase-separated morphology undergoes a transition to a micro-phase-separation-like morphology via a lorate morphology as a metastable state. The transition leads to the emergence of monodisperse nanosized domains through repeated domain scission events. Moreover, we have numerically confirmed the transitions using the time-dependent Ginzburg-Landau model describing phase separation and the bending elastic membrane, which is quantitatively consistent with experimental results by fixing one free parameter. Our findings suggest that the local spontaneous curvature due to the asymmetric composition plays an essential role in the thermodynamic stabilization of micro-phase separation in lipid bilayers.

  17. Incorporating Memory Effects in Phase Separation Processes

    CERN Document Server

    Koide, T; Ramos, R O; Ramos, Rudnei O.


    We consider the modification of the Cahn-Hilliard equation when a time delay process through a memory function is taken into account. We then study the process of spinodal decomposition in fast phase transitions associated with a conserved order parameter. Finite-time memory effects are seen to affect the dynamics of phase transition at short times and have the effect of delaying, in a significant way, the explosive spinodal decomposition. These effects are important in several systems characterized by fast processes, like nonequilibrium dynamics in the early universe and in relativistic heavy-ion collisions.

  18. Membranes as separators of dispersed emulsion phases

    NARCIS (Netherlands)

    Lefferts, A.G.


    The reuse or discharge of industrial waste waters, containing small fractions of dispersed oil, requires a purification treatment for which membranes can be used. If only little oil is present, removal of the dispersed phase might be preferable to the more commonly applied removal of the

  19. Segregative phase separation in aqueous mixtures of polydisperse biopolymers

    NARCIS (Netherlands)

    Edelman, M.W.


    Keywords: biopolymer, gelatine, dextran, PEO, phase separation, polydispersity, molar mass distribution, SEC-MALLS, CSLM The temperature-composition phase diagram of aqueous solutions of gelatine and dextran, which show liquid/liquid phase segregation, were explored at temperatures above the gelatio

  20. Phase separating colloid polymer mixtures in shear flow

    NARCIS (Netherlands)

    Derks, D.; Aarts, D.G.A.L.; Bonn, D.; Imhof, A.


    We study the process of phase separation of colloid polymer mixtures in the (spinodal) two-phase region of the phase diagram in shear flow. We use a counter-rotating shear cell and image the system by means of confocal laser scanning microscopy. The system is quenched from an initially almost homoge

  1. Phase separating colloid polymer mixtures in shear flow

    NARCIS (Netherlands)

    Derks, D.; Aarts, D.; Bonn, D.; Imhof, A.


    We study the process of phase separation of colloid polymer mixtures in the (spinodal) two-phase region of the phase diagram in shear flow. We use a counter-rotating shear cell and image the system by means of confocal laser scanning microscopy. The system is quenched from an initially almost

  2. Speciation and phase separation of water in quartz (A review ...

    African Journals Online (AJOL)

    Speciation and phase separation of water in quartz (A review) ... of quartz at temperatures in excess of 500 °C. leading to decomposition of the ... The nucleation is a first order phase transition of creating liquid nucleus within the vapour phase, ...

  3. A Phase Separation Fluoroimmunoassay of Estradiol

    Institute of Scientific and Technical Information of China (English)

    WANG,Yong-Cheng(王永成); ZHAO,Jin-Fu(赵金富); LI,Yuan-Zong(李元宗); CHANG,Wen-Bao(常文保); GUO,Zhen-Quan(郭振泉)


    A competitive indirect fluoroinmnunoassay of free estradiol(E2) was established based on the thermal sensitivity of hy-drogel-poly-N-isopropylacrylamide.Free estradiol was cova-lently bound to bovine sermn albumin (BSA) to form com-plete antigen (F2-BSA),which was in turn labeled by fluores-cein isothiocyanate (FITC) as the fluorescence probe.The an-ti- F2 monodonal anfibody (Mc Ab) was prepared by anin vivo method,and coupled with N-isopropylacrylamide (NIPA)to make an immune copolymer,poly-N-isopropylacylamide-monodonal antibody (pNIPA-McAb),for the deterniiration of free F2.The immunoassay method was based on the com-petitive binding of free F2 and fluoresceinated antigen (F2-BSA-FITC) with limited amount of pNIPA-McAb.When theinmunological reaction was over,precipitation and centrifugalprocedures were carried ont to separate pNIPA-McAb-F2-BSA-FITC from other constituents in solution.The precipitatepNIPA-McAb-F2-BSA-FITC was dissolved in solution andthen the fluorescence intensity was measured.The calibrationcurve covered a range of 78-500 ng/mL for free F2.The re-coveries were 91,2-107.2%.``

  4. The studies of phase equilibria and efficiency assessment for self-emulsifying lipid-based formulations. (United States)

    Shahba, Ahmad Abdul-Wahhab; Mohsin, Kazi; Alanazi, Fars Kaed


    The study was designed to build up a database for the evaluation of the self-emulsifying lipid formulations performance. A standard assessment method was constructed to evaluate the self-emulsifying efficiency of the formulations based on five parameters including excipients miscibility, spontaneity, dispersibility, homogeneity, and physical appearance. Equilibrium phase studies were conducted to investigate the phase changes of the anhydrous formulation in response to aqueous dilution. Droplet size studies were carried out to assess the influence of lipid and surfactant portions on the resulted droplet size upon aqueous dilution. Formulations containing mixed glycerides showed enhanced self-emulsification with both lipophilic and hydrophilic surfactants. Increasing the polarity of the lipid portion in the formulation leaded to progressive water solubilization capacity. In addition, formulations containing medium chain mixed glycerides and hydrophilic surfactants showed lower droplet size compared with their long chain and lipophilic counterparts. The inclusion of mixed glycerides in the lipid formulations enormously enhances the formulation efficiency.

  5. Formation of porous crystals via viscoelastic phase separation (United States)

    Tsurusawa, Hideyo; Russo, John; Leocmach, Mathieu; Tanaka, Hajime


    Viscoelastic phase separation of colloidal suspensions can be interrupted to form gels either by glass transition or by crystallization. With a new confocal microscopy protocol, we follow the entire kinetics of phase separation, from homogeneous phase to different arrested states. For the first time in experiments, our results unveil a novel crystallization pathway to sponge-like porous crystal structures. In the early stages, we show that nucleation requires a structural reorganization of the liquid phase, called stress-driven ageing. Once nucleation starts, we observe that crystallization follows three different routes: direct crystallization of the liquid phase, the Bergeron process, and Ostwald ripening. Nucleation starts inside the reorganized network, but crystals grow past it by direct condensation of the gas phase on their surface, driving liquid evaporation, and producing a network structure different from the original phase separation pattern. We argue that similar crystal-gel states can be formed in monatomic and molecular systems if the liquid phase is slow enough to induce viscoelastic phase separation, but fast enough to prevent immediate vitrification. This provides a novel pathway to form nanoporous crystals of metals and semiconductors without dealloying, which may be important for catalytic, optical, sensing, and filtration applications.

  6. Chromatographic Separations Using Solid-Phase Extraction Cartridges: Separation of Wine Phenolics (United States)

    Brenneman, Charles A.; Ebeler, Susan E.


    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.

  7. Laser-induced phase separation of silicon carbide (United States)

    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


    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.

  8. Cytoskeletal pinning controls phase separation in multicomponent lipid membranes. (United States)

    Arumugam, Senthil; Petrov, Eugene P; Schwille, Petra


    We study the effect of a minimal cytoskeletal network formed on the surface of giant unilamellar vesicles by the prokaryotic tubulin homolog, FtsZ, on phase separation in freestanding lipid membranes. FtsZ has been modified to interact with the membrane through a membrane targeting sequence from the prokaryotic protein MinD. FtsZ with the attached membrane targeting sequence efficiently forms a highly interconnected network on membranes with a concentration-dependent mesh size, much similar to the eukaryotic cytoskeletal network underlying the plasma membrane. Using giant unilamellar vesicles formed from a quaternary lipid mixture, we demonstrate that the artificial membrane-associated cytoskeleton, on the one hand, suppresses large-scale phase separation below the phase transition temperature, and, on the other hand, preserves phase separation above the transition temperature. Our experimental observations support the ideas put forward in our previous simulation study: In particular, the picket fence effect on phase separation may explain why micrometer-scale membrane domains are observed in isolated, cytoskeleton-free giant plasma membrane vesicles, but not in intact cell membranes. The experimentally observed suppression of large-scale phase separation much below the transition temperatures also serves as an argument in favor of the cryoprotective role of the cytoskeleton. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  9. Construction of Pseudoternary Phase Diagram and its Evaluation: Development of Self-dispersible Oral Formulation

    Directory of Open Access Journals (Sweden)

    Javed Ahmad


    Full Text Available The purpose of this study is to give an insight into the significance of pseudoternary phase diagram construction and its evaluation, as an important tool for the development of lipid based selfdispersible oral formulation. This formulation was designed in order to improve the oral efficacy of hydrophobic drug, which display dissolution rate limited absorption. Construction of pseudoternary phase diagram is an important tool for screening of self-dispersible formulation components and to assess the effect of different component on in-vitro performance of formulation. Spontaneity of formulation to convert into nano drug carrier and robustness to dilution inside gastrointestinal lumen is an important aspect of such lipid based formulation to predict its in-vivo performance. Thus our study provides an important tool for designing of lipid based formulation for improved oral delivery of low bioavailable drug.

  10. Phase separation behavior of fusidic acid and rifampicin in PLGA microspheres. (United States)

    Gilchrist, Samuel E; Rickard, Deborah L; Letchford, Kevin; Needham, David; Burt, Helen M


    The purpose of this study was to characterize the phase separation behavior of fusidic acid (FA) and rifampicin (RIF) in poly(d,l-lactic acid-co-glycolic acid) (PLGA) using a model microsphere formulation. To accomplish this, microspheres containing 20% FA with 0%, 5%, 10%, 20%, and 30% RIF and 20% RIF with 30%, 20% 10%, 5%, and 0% FA were prepared by solvent evaporation. Drug-polymer and drug-drug compatibility and miscibility were characterized using laser confocal microscopy, Raman spectroscopy, XRPD, DSC, and real-time video recordings of single-microsphere formation. The encapsulation of FA and RIF alone, or in combination, results in a liquid-liquid phase separation of solvent-and-drug-rich microdomains that are excluded from the polymer bulk during microsphere hardening, resulting in amorphous spherical drug-rich domains within the polymer bulk and on the microsphere surface. FA and RIF phase separate from PLGA at relative droplet volumes of 0.311 ± 0.014 and 0.194 ± 0.000, respectively, predictive of the incompatibility of each drug and PLGA. When coloaded, FA and RIF phase separate in a single event at the relative droplet volume 0.251 ± 0.002, intermediate between each of the monoloaded formulations and dependent on the relative contribution of FA or RIF. The release of FA and RIF from phase-separated microspheres was characterized exclusively by a burst release and was dependent on the phase exclusion of surface drug-rich domains. Phase separation results in coalescence of drug-rich microdroplets and polymer phase exclusion, and it is dependent on the compatibility between FA and RIF and PLGA. FA and RIF are mutually miscible in all proportions as an amorphous glass, and they phase separate from the polymer as such. These drug-rich domains were excluded to the surface of the microspheres, and subsequent release of both drugs from the microspheres was rapid and reflected this surface location.

  11. Phase separation during radiation crosslinking of unsaturated polyester resin (United States)

    Pucić, Irina; Ranogajec, Franjo


    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.


    Directory of Open Access Journals (Sweden)

    P. Hajivand


    Full Text Available Abstract In this study, various water-soluble and oil-soluble demulsifiers were selected for separation of water from crude oil emulsions and their productivity measured using the Bottle-test method at 70 °C and 10 ppm concentration. The best ones among 23 demulsifiers examined through the screening process were fatty alcohol ethoxylate, triethanol amine and urea from the water-soluble group and Basororol E2032, Basorol PDB 9935 and TOMAC from the oil-soluble category. Furthermore, the present study investigated the factors effective for demulsification such as temperature, concentration, pH, salinity and modifiers. It was found that the separation improves with increasing demulsifier concentration, increasing salt content, increasing temperature up to 80 °C, keeping the pH values between 5-9. Adding solvent modifiers proved unnecessary. Two formulations were prepared based on suggested optimal concentrations of demulsifier content by experimental design using Qualitec 4 and these proved to be highly effective in treating real and synthetic emulsions.

  13. Quantum and Classical Phase Space Separability and Entanglement

    CERN Document Server

    Patwardhan, A


    The formalism of classical and quantum mechanics on phase space leads to symplectic and Heisenberg group representations, respectively. The Wigner functions give a representation of the quantum system using classical variables. The correspondence between the classical and the quantum criterion of separability for the system is obtained in terms of these functions. Entanglement is generic and separability is special. Some applications are discussed in commonly occuring examples and possibly in exotic systems.

  14. Kinetics of phase separation in systems exhibiting simple coacervation (United States)

    Gupta, Amarnath; Bohidar, H. B.


    The kinetics of phase separation of a homogeneous polyelectrolytic solution into a dense polymer-rich coacervate and the dilute supernatant phase is discussed through statistical thermodynamics. It has been shown that the coacervate phase is associated with higher internal pressure, consequently giving rise to syneresis. Physical conditions for phase separations has been deduced explicitly which reveals that σ2/I⩾ constant (where σ is polyelectrolyte charge density and I is solution ionic strength), consistent with experimental observations. In the lattice model, r is the number of sites occupied by the polymer having a volume critical fraction φ2c , it was found that phase separation would ensue when σ3r⩾(64/9α2)[φ2c/(1-φ2c)2] , which reduces to (σ3r/φ2c)⩾(64/9α2)≈0.45 at 20 °C for φ2c≪1 . The separation kinetics mimics a spinodal decomposition process. Rate of release of supernatant due to syneresis was found to be independent of the initial coacervate mass. Syneresis results are discussed in the context of temporal evolution of self-organization in polymer melts through Avrami model.

  15. Phase separation in dense glassy liquids: effect of quenching protocols (United States)

    Chaudhuri, Pinaki; Horbach, Jürgen


    Extensive molecular dynamics simulations are used to investigate the phase separation kinetics in a glass-forming binary Lennard-Jones mixture. The focus is on the two-phase region at low temperatures (i.e. below the glass transition line), where coexistence between a low-density gas with a metastable amorphous solid, i.e. a glass occurs. Two different quench paths are chosen to get into the two-phase region starting from a structurally homogeneous state, one along which temperature is lowered at a fixed density, and in the other case, the volume is expanded to reach lower densities at fixed temperatures. Both paths are explored by tuning the rates of cooling or expansion, respectively. We analyze thermodynamic and structural properties of the phase-separating systems, in particular with respect to differences in the morphologies that are obtained from the different quench protocols.

  16. Numerical simulations of the phase separation properties for the thermal aged CDSS with Phase Field Model

    Energy Technology Data Exchange (ETDEWEB)

    Xue Fei [Department of Material Science and Engineering, Tsinghua University, Beijing 100084 (China); Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); Wang Zhaoxi, E-mail: [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); Applied Mechanics Laboratory, Tsinghua University, Beijing 100084 (China); Zhang Guodong [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); School of Mechanical and Power Engineering, Nanjing University of Technology, Nanjing 210009 (China); Qu Baoping; Shi Huiji [Applied Mechanics Laboratory, Tsinghua University, Beijing 100084 (China); Shu Guogang [Suzhou Nuclear Power Research Institute, Suzhou 215004 (China); Liu Wei [Department of Material Science and Engineering, Tsinghua University, Beijing 100084 (China)


    Highlights: > Thermal aging causes the Cr-rich phase precipitate and form clusters. > Phase field dynamic model is used for simulating the phase separation coarsening. > Damage initiated more easily in the ferrite matrix for the Cr clusters. - Abstract: Experiments and numerical simulations with Phase Field Model and Finite Element Analysis were carried out to investigate the phase separation dynamic properties and the corresponding thermal aging degradation mechanism. Experimental results from transmission electron microscopy and atomic force microscopy show that thermal aging causes the Cr-rich phase precipitate and form clusters. A phase field dynamic model was developed with constitutive relations and empirical potential functions to investigate the phase separation dynamics in the ferrite phase. Numerical results integrated with cell dynamical system method show clearly the micro structure morphology and the phase separation coarsening with aging time. The evolution process of the phase separation was quantitatively illustrated and reproduced macroscopically. The scattering pattern becomes clearer and the corresponding radius becomes smaller along with the increasing aging time. The average characteristic length increases firstly then decreases and enters a more stable stage. With the increment of the local Cr concentration, the evolution of the phase morphology was quite different. Finite Element Analysis simulation results with the Gurson-Tvergaard-Needleman void model show that the damage initiated more easily in the ferrite matrix for the Cr atoms forming clusters with increasing aging time. The phenomenological simulations with Phase Field Model and Finite Element Analysis were in remarkably good agreement with experimental results and analytical considerations.

  17. Simultaneous Chiral SeparationUsing a Combinatorial Molecular Imprinting Phase

    Institute of Scientific and Technical Information of China (English)


    Molecular imprinting chiral stationary phase against Cbz-L-Serine (Cbz-L-Ser) and Cbz-L-Alaine (Cbz-L-Ala) were prepared utilizing acrylamide + 2-vinylpyridine as combined basic functional monomers.Cross-selectivity was used to obtain simultaneous chiral separations of Cbz-DL-Ser and Cbz-DL-Ala by connecting two columns packed with Cbz-L-Ser and Cbz-L-Ala imprinted chiral stationary phase, respectively.

  18. Phase transition in Caenorhabditis elegans: A classical oil-water phase separation? (United States)

    Weber, Christoph; Tony Hyman Collaboration; Andrés Delgadillo Collaboration; Frank Jülicher Team


    In Caenorhabditis elegans droplets form before the cell divides. These droplets, also referred to as P-granules, consist of a variety of unstructured proteins and mRNA. Brangwynne et al. [Science, 2009] showed that the P-granules exhibit fluid-like behavior and that the phase separation is controlled spatially by a gradient of a component called Mex-5. It is believed that this system exhibits the same characteristics as a classical oil-water phase separation. Here we report the recent experimental investigations on the phase separation in Caenorhabditis elegans and compare our findings with a classical oil-water phase separation. Specifically, we consider the underlying coarsening mechanisms as well as the impact of temperature and species composition. Finally, we present a preliminary model incorporating the characteristics of the phase separation kinetics for Caenorhabditis elegans.


    Directory of Open Access Journals (Sweden)

    Manoj S. Charde


    Full Text Available A simple, sensitive and reproducible reverse-phase high performance liquid chromatographic (RP-HPLC method has been developed for the quantitative estimation of Telmisartan (TELM in the pharmaceutical formulations. Chromatographic separation was achieved on a 250 × 4.6 mm, 5μ, Waters symmetry column. The flow rate was 1 ml/min and eluent was monitored by absorbance at 230 nm using a mixture of Methanol and Acetonitrile (pH 3.0±0.01 in the ratio of 30:70 (v/v. The retention time of Telmisartan was found to be 7.9 min. Calibration plots were linear in the concentration range of 10-50 μg/ml for Telmisartan with correlation coefficient (R2 0.999. The proposed method was validated by testing its linearity, recovery, specificity, system suitability, precision (Interday, intraday, analyst and instrument precision, robustness and LOD/LOQ values and it was successfully employed for the determination of Telmisartan in pharmaceutical tablet formulations.

  20. Separation of pigment formulations by high-performance thin-layer chromatography with automated multiple development. (United States)

    Stiefel, Constanze; Dietzel, Sylvia; Endress, Marc; Morlock, Gertrud E


    Food packaging is designed to provide sufficient protection for the respective filling, legally binding information for the consumers like nutritional facts or filling information, and an attractive appearance to promote the sale. For quality and safety of the package, a regular quality control of the used printing materials is necessary to get consistently good print results, to avoid migration of undesired ink components into the food and to identify potentially faulty ink batches. Analytical approaches, however, have hardly been considered for quality assurance so far due to the lack of robust, suitable methods for the analysis of rarely soluble pigment formulations. Thus, a simple and generic high-performance thin-layer chromatography (HPTLC) method for the separation of different colored pigment formulations was developed on HPTLC plates silica gel 60 by automated multiple development. The gradient system provided a sharp resolution for differently soluble pigment constituents like additives and coating materials. The results of multi-detection allowed a first assignment of the differently detectable bands to particular chemical substance classes (e.g., lipophilic components), enabled the comparison of different commercially available pigment batches and revealed substantial variations in the composition of the batches. Hyphenation of HPTLC with high resolution mass spectrometry and infrared spectroscopy allowed the characterization of single unknown pigment constituents, which may partly be responsible for known quality problems during printing. The newly developed, precise and selective HPTLC method can be used as part of routine quality control for both, incoming pigment batches and monitoring of internal pigment production processes, to secure a consistent pigment composition resulting in consistent ink quality, a faultless print image and safe products. Hyphenation of HPTLC with the A. fischeri bioassay gave first information on the bioactivity or rather

  1. Creating Drug Solubilization Compartments via Phase Separation in Multicomponent Buccal Patches Prepared by Direct Hot Melt Extrusion-Injection Molding

    NARCIS (Netherlands)

    Alhijjaj, Muqdad; Bouman, Jacob; Wellner, Nikolaus; Belton, Peter; Qi, Sheng


    Creating in situ phase separation in solid dispersion based formulations to allow enhanced functionality of the dosage form, such as improving dissolution of poorly soluble model drug as well as being mucoadhesive, can significantly maximize the in vitro and in vivo performance of the dosage form

  2. Three-dimensional microwave imaging for breast-cancer detection using the log-phase formulation

    DEFF Research Database (Denmark)

    Rubæk, Tonny; Meincke, Peter; Kim, Oleksiy S.


    The log-phase formulation is applied for the reconstruction of images from a simulation of a three-dimensional imaging system. By using this formulation, a clear improvement in the quality of the reconstructed images is achieved compared to the case in which the usual complex phasor notation is e...

  3. Modeling Human Population Separation History Using Physically Phased Genomes (United States)

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


    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

  4. Separation of Chlorella vulgaris from liquid phase using bioflocculants

    Directory of Open Access Journals (Sweden)

    Gizem Günay


    results showed that C. vulgaris was partially separated from the liquid phase. However, the experiments will continue for the purpose of increasing the flocculating activity. Getting successfully experimental results with kaolin showed that bioflocculant has a potential use in wastewater treatment. For this reason, it also is thought to analyze the effect of bioflocculant on the wastewater treatment with further studies.[¤

  5. Influence of phase separator design on the performance of UASB ...

    African Journals Online (AJOL)


    Apr 2, 2016 ... above the conventional phase separator design of triangular prisms with an open base. .... ing a high-rate settler, a system often used in water treatment plants. ..... waste water in fixed film reactors – A literature review. Water ...

  6. Small Corrections to the Tunneling Phase Time Formulation

    CERN Document Server

    Bernardini, Alex E


    After reexamining the above barrier diffusion problem where we notice that the wave packet collision implies the existence of {\\em multiple} reflected and transmitted wave packets, we analyze the way of obtaining phase times for tunneling/reflecting particles in a particular colliding configuration where the idea of multiple peak decomposition is recovered. To partially overcome the analytical incongruities which frequently rise up when the stationary phase method is adopted for computing the (tunneling) phase time expressions, we present a theoretical exercise involving a symmetrical collision between two identical wave packets and a unidimensional squared potential barrier where the scattered wave packets can be recomposed by summing the amplitudes of simultaneously reflected and transmitted wave components so that the conditions for applying the stationary phase principle are totally recovered. Lessons concerning the use of the stationary phase method are drawn.

  7. Metallic and semiconducting carbon nanotubes separation using an aqueous two-phase separation technique: a review (United States)

    Tang, Malcolm S. Y.; Ng, Eng-Poh; Juan, Joon Ching; Ooi, Chien Wei; Ling, Tau Chuan; Woon, Kai Lin; Loke Show, Pau


    It is known that carbon nanotubes show desirable physical and chemical properties with a wide array of potential applications. Nonetheless, their potential has been hampered by the difficulties in acquiring high purity, chiral-specific tubes. Considerable advancement has been made in terms of the purification of carbon nanotubes, for instance chemical oxidation, physical separation, and myriad combinations of physical and chemical methods. The aqueous two-phase separation technique has recently been demonstrated to be able to sort carbon nanotubes based on their chirality. The technique requires low cost polymers and salt, and is able to sort the tubes based on their diameter as well as metallicity. In this review, we aim to provide a review that could stimulate innovative thought on the progress of a carbon nanotubes sorting method using the aqueous two-phase separation method, and present possible future work and an outlook that could enhance the methodology.

  8. An Alternative Formulation of Hall Effect and Quantum Phases in Noncommutative Space

    CERN Document Server

    Dayi, O F


    A recent method of constructing quantum mechanics in noncommutative coordinates alternative to imply noncommutativity by means of star product or the equivalent coordinate shift is discussed. The formulation is based on introducing some generalized theta-deformed commutation relations among quantum phase space variables and providing their realizations. Each realization furnishes us with a diverse theta-deformation. This procedure is suitable to consider theta-deformation of matrix observables which may be even coordinate independent. Within this alternative approach we give a formulation of Hall effect in noncommutative coordinates and calculate the deformed Hall conductivities for the realizations adopted. Before presenting our formulation of the theta-deformed quantum phases we discussed in a unified manner the existing formulations of quantum phases in noncommutative coordinates. The theta-deformed Aharonov-Bohm, Aharonov-Casher, He-McKellar-Wilkens and Anandan phases which we obtain are not velocity depe...

  9. Study of phase separation using liquid-gas model of lattice-gas cellular automata

    Energy Technology Data Exchange (ETDEWEB)

    Ebihara, Kenichi; Watanabe, Tadashi; Kaburaki, Hideo [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment


    This report describes the study of phase separation by the liquid gas model of lattice gas cellular automata. The lattice gas cellular automaton is one model for simulating fluid phenomena which was proposed by Frisch, Hasslacher and Pomeau in 1986. In 1990, Appert and Zaleski added a new long-range interaction to lattice gas cellular automata to construct a model, the liquid-gas model, which could simulate phase separation using lattice-gas cellular automata. Gerits et al formulated the liquid-gas model mathematically using the theory of statistical dynamics in 1993 and explained the mechanism of phase separation in the liquid-gas model using the equation of state. At first this report explains the FHP model of lattice gas cellular automata and derives fluid dynamics equations such as the equation of continuity and the Navier-Stokes equation. Then the equation of state for the liquid-gas model which was derived by Gerits et al is modified by adding the interactions which were proposed by Appert but not considered by Gerits et al. The modified equation of state is verified by the computer simulation using the liquid gas model. The relation between phase separation and the equation of state is discussed. (author)

  10. The Phase Space Formulation of Time-Symmetric Quantum Mechanics

    National Research Council Canada - National Science Library

    Charlyne de Gosson; Maurice A. de Gosson


    Time-symmetric quantum mechanics can be described in the Weyl–Wigner–Moyal phase space formalism by using the properties of the cross-terms appearing in the Wigner distribution of a sum of states...

  11. QCD Phase Transition in a new Hybrid Model Formulation

    CERN Document Server

    Srivastava, P K


    Search of a proper and realistic equations of state (EOS) for strongly interacting matter used in the study of QCD phase diagram still appears as a challenging task. Recently, we have constructed a hybrid model description for the quark gluon plasma (QGP) as well as hadron gas (HG) phases where we use a new excluded-volume model for HG and a thermodynamically-consistent quasiparticle model for the QGP phase. We attempt to use them to get a QCD phase boundary and a critical point. We test our hybrid model by reproducing the entire lattice QCD data for strongly interacting matter at zero baryon chemical potential ($\\mu_{B}$)and predict the results at finite $\\mu_{B}$ and $T$.

  12. Implementing Effective Mission Systems Engineering Practices During Early Project Formulation Phases (United States)

    Moton, Tryshanda


    Developing and implementing a plan for a NASA space mission can be a complicated process. The needs, goals, and objectives of any proposed mission or technology must be assessed early in the Project Life Cycle. The key to successful development of a space mission or flight project is the inclusion of systems engineering in early project formulation, namely during Pre-phase A, Phase A, and Phase B of the NASA Project Life Cycle. When a space mission or new technology is in pre-development, or "pre-Formulation", feasibility must be determined based on cost, schedule, and risk. Inclusion of system engineering during project formulation is key because in addition to assessing feasibility, design concepts are developed and alternatives to design concepts are evaluated. Lack of systems engineering involvement early in the project formulation can result in increased risks later in the implementation and operations phases of the project. One proven method for effective systems engineering practice during the pre-Formulation Phase is the use of a mission conceptual design or technology development laboratory, such as the Mission Design Lab (MDL) at NASA's Goddard Space Flight Center (GSFC). This paper will review the engineering process practiced routinely in the MDL for successful mission or project development during the pre-Formulation Phase.

  13. Phase separation dynamics during Myxococcus xanthus fruiting body formation (United States)

    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.

  14. Electric field tuning of phase separation in manganite thin films

    KAUST Repository

    Lourembam, James


    In this paper, we investigate the electric field effect on epitaxial Pr0.65(Ca0.75Sr0.25)0.35MnO3 thin films in electric double-layer transistors. Different from the conventional transistors with semiconducting channels, the sub(micrometer)-scale phase separation in the manganite channels is expected to result in inhomogeneous distribution of mobile carriers and local enhancement of electric field. The field effect is much larger in the low-temperature phase separation region compared to that in the high-temperature polaron transport region. Further enhancement of electroresistance is achieved by applying a magnetic field, and a 250% modulation of resistance is observed at 80 K, equivalent to an increase of the ferromagnetic metallic phase fraction by 0.51%, as estimated by the general effective medium model. Our results illustrate the complementary nature of electric and magnetic field effects in phase-separated manganites, providing insights on such novel electronic devices based on complex oxides.

  15. Entanglement and separability in the noncommutative phase-space scenario

    CERN Document Server

    Bernardini, Alex E; Bertolami, Orfeu; Dias, Nuno C; Prata, João N


    Quantumness and separability criteria for continuous variable systems are discussed for the case of a noncommutative (NC) phase-space. In particular, the quantum nature and the entanglement configuration of NC two-mode Gaussian states are examined. Two families of covariance matrices describing standard quantum mechanics (QM) separable states are deformed into a NC QM configuration and then investigated through the positive partial transpose criterium for identifying quantum entanglement. It is shown that the entanglement of Gaussian states may be exclusively induced by switching on the NC deformation. Extensions of some preliminary results are presented.

  16. Re-entrant phase behavior for systems with competition between phase separation and self-assembly. (United States)

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


    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.

  17. Phase separation of metallic hydrogen-helium alloys (United States)

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


    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.

  18. Vitrification and Crystallization of Phase-Separated Metallic Liquid

    Directory of Open Access Journals (Sweden)

    Yun Cheng


    Full Text Available The liquid–liquid phase separation (LLPS behavior of Fe50Cu50 melt from 3500 K to 300 K with different rapid quenching is investigated by molecular dynamics (MD simulation based on the embedded atom method (EAM. The liquid undergoes metastable phase separation by spinodal decomposition in the undercooled regime and subsequently solidifies into three different Fe-rich microstructures: the interconnected-type structure is kept in the glass and crystal at a higher cooling rate, while the Fe-rich droplets are found to crystalize at a lower cooling rate. During the crystallization process, only Fe-rich clusters can act as the solid nuclei. The twinning planes can be observed in the crystal and only the homogeneous atomic stacking shows mirror symmetry along the twinning boundary. Our present work provides atomic-scale understanding of LLPS melt during the cooling process.

  19. Fibril Formation and Phase Separation in Aqueous Cellulose Ethers (United States)

    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.

  20. GPU accelerated numerical simulations of viscoelastic phase separation model. (United States)

    Yang, Keda; Su, Jiaye; Guo, Hongxia


    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.

  1. The Phase Space Formulation of Time-Symmetric Quantum Mechanics

    Directory of Open Access Journals (Sweden)

    Charlyne de Gosson


    Full Text Available Time-symmetric quantum mechanics can be described in the Weyl–Wigner–Moyal phase space formalism by using the properties of the cross-terms appearing in the Wigner distribution of a sum of states. These properties show the appearance of a strongly oscillating interference between the pre-selected and post-selected states. It is interesting to note that the knowledge of this interference term is sufficient to reconstruct both states.Quanta 2015; 4: 27–34.

  2. Evaluation of phase separator number in hydrodesulfurization (HDS) unit (United States)

    Jayanti, A. D.; Indarto, A.


    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.

  3. Phase separation in artificial vesicles driven by light and curvature (United States)

    Rinaldin, Melissa; Pomp, Wim; Schmidt, Thomas; Giomi, Luca; Kraft, Daniela; Physics of Life Processes Team; Soft; Bio Mechanics Collaboration; Self-Assembly in Soft Matter Systems Collaboration

    The role of phase-demixing in living cells, leading to the lipid-raft hypothesis, has been extensively studied. Lipid domains of higher lipid chain order are proposed to regulate protein spatial organization. Giant Unilamellar Vesicles provide an artificial model to study phase separation. So far temperature was used to initiate the process. Here we introduce a new methodology based on the induction of phase separation by light. To this aim, the composition of the lipid membrane is varied by photo-oxidation of lipids. The control of the process gained by using light allowed us to observe vesicle shape fluctuations during phase-demixing. The presence of fluctuations near the critical mixing point resembles features of a critical process. We quantitatively analyze these fluctuations using a 2d elastic model, from which we can estimate the material parameters such as bending rigidity and surface tension, demonstrating the non-equilibrium critical behaviour. Finally, I will describe recent attempts toward tuning the membrane composition by controlling the vesicle curvature.

  4. Phase Separation in Poly(urethane urea) Multiblock Copolymers (United States)

    Garrett, J. T.; Xu, R.; Cho, J.; Runt, J.


    The current paper is a continuation of our research on microdomain morphology and phase separation of model poly(urethane urea) copolymers, complimenting our previous AFM and small-angle x-ray scattering studies. Phase transitions were monitored using both dynamic mechanical analysis and DSC, taking care to keep the temperature below where chemical degradation becomes significant. Surprisingly, soft phase Tgs were found to consistently decrease in temperature with increasing hard segment content in the copolymers. This is seemingly in contrast with an increase in unlike segment mixing in the domains with increasing hard segment content, as determined from SAXS. Several possible explanations for this behavior are proposed. The nature of the hard domains was also characterized using wide-angle x-ray diffraction experiments. Evidence of very weak crystalline diffraction peak(s) where found, superimposed on the amorphous halo. Finally, we also evaluated the sensitivity of Fourier transform infrared spectroscopy to hard/soft segment phase separation in these systems.

  5. Thermodynamics of the motility-induced phase separation (United States)

    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.

  6. Applications of the IAPWS-95 formulation in fluid inclusion and mineral-fluid phase equilibria

    Directory of Open Access Journals (Sweden)

    Lanlan Shi


    Full Text Available The IAPWS-95 formulation explicit in Helmholtz free energy proposed by Wagner and Pruβ (2002 is the best equation of state of water, from which all thermodynamic properties can be obtained over a wide T–p range from 273.16 to 1273 K and from 0 to 1000 MPa with experimental accuracy. This paper reports the applications of the IAPWS-95 formulation in fluid inclusion and mineral-water phase equilibria. A reliable and highly efficient calculation method is presented for the saturated properties of water so that the formulation can be conveniently applied in the study of fluid inclusion, such as calculating homogenization pressures, homogenization densities (or molar volumes, volume fractions and isochores. Meanwhile, the univariant curves of some mineral-dehydration reactions are calculated based on the IAPWS-95 formulation. The computer code of the IAPWS-95 formulation can be obtained from the corresponding author.

  7. Phase-space noncommutative formulation of Ozawa's uncertainty principle (United States)

    Bastos, Catarina; Bernardini, Alex E.; Bertolami, Orfeu; Costa Dias, Nuno; Prata, João Nuno


    Ozawa's measurement-disturbance relation is generalized to a phase-space noncommutative extension of quantum mechanics. It is shown that the measurement-disturbance relations have additional terms for backaction evading quadrature amplifiers and for noiseless quadrature transducers. Several distinctive features appear as a consequence of the noncommutative extension: measurement interactions which are noiseless, and observables which are undisturbed by a measurement, or of independent intervention in ordinary quantum mechanics, may acquire noise, become disturbed by the measurement, or no longer be an independent intervention in noncommutative quantum mechanics. It is also found that there can be states which violate Ozawa's universal noise-disturbance trade-off relation, but verify its noncommutative deformation.

  8. A mathematical formulation of the random phase approximation for crystals

    CERN Document Server

    Cances, Eric


    This works extends the recent study on the dielectric permittivity of crystals within the Hartree model [E. Cances and M. Lewin, Arch. Rational Mech. Anal., 197 (2010) 139--177] to the time-dependent setting. In particular, we prove the existence and uniqueness of the nonlinear Hartree dynamics, also called the random phase approximation in the physics literature, in a suitable functional space allowing to describe a local defect embedded in a perfect crystal. We also give a rigorous mathematical definition of the microscopic frequency-dependent polarization matrix, and derive the macroscopic Maxwell-Gauss equation for insulating and semiconducting crystals, from a first order approximation of the nonlinear Hartree model, by means of homogenization arguments.

  9. Influence of humidity on the phase behavior of API/polymer formulations. (United States)

    Prudic, Anke; Ji, Yuanhui; Luebbert, Christian; Sadowski, Gabriele


    Amorphous formulations of APIs in polymers tend to absorb water from the atmosphere. This absorption of water can induce API recrystallization, leading to reduced long-term stability during storage. In this work, the phase behavior of different formulations was investigated as a function of relative humidity. Indomethacin and naproxen were chosen as model APIs and poly(vinyl pyrrolidone) (PVP) and poly(vinyl pyrrolidone-co-vinyl acetate) (PVPVA64) as excipients. The formulations were prepared by spray drying. The water sorption in pure polymers and in formulations was measured at 25°C and at different values of relative humidity (RH=25%, 50% and 75%). Most water was absorbed in PVP-containing systems, and water sorption was decreasing with increasing API content. These trends could also be predicted in good agreement with the experimental data using the thermodynamic model PC-SAFT. Furthermore, the effect of absorbed water on API solubility in the polymer and on the glass-transition temperature of the formulations was predicted with PC-SAFT and the Gordon-Taylor equation, respectively. The absorbed water was found to significantly decrease the API solubility in the polymer as well as the glass-transition temperature of the formulation. Based on a quantitative modeling of the API/polymer phase diagrams as a function of relative humidity, appropriate API/polymer compositions can now be selected to ensure long-term stable amorphous formulations at given storage conditions.

  10. Molecularly imprinted solid phase extraction of fluconazole from pharmaceutical formulations. (United States)

    Manzoor, S; Buffon, R; Rossi, A V


    This work encompasses a direct and coherent strategy to synthesise a molecularly imprinted polymer (MIP) capable of extracting fluconazole from its sample. The MIP was successfully prepared from methacrylic acid (functional monomer), ethyleneglycoldimethacrylate (crosslinker) and acetonitrile (porogenic solvent) in the presence of fluconazole as the template molecule through a non-covalent approach. The non-imprinted polymer (NIP) was prepared following the same synthetic scheme, but in the absence of the template. The data obtained from scanning electronic microscopy, infrared spectroscopy, thermogravimetric and nitrogen Brunauer-Emmett-Teller plot helped to elucidate the structural as well as the morphological characteristics of the MIP and NIP. The application of MIP as a sorbent was demonstrated by packing it in solid phase extraction cartridges to extract fluconazole from commercial capsule samples through an offline analytical procedure. The quantification of fluconazole was accomplished through UPLC-MS, which resulted in LOD≤1.63×10(-10) mM. Furthermore, a high percentage recovery of 91±10% (n=9) was obtained. The ability of the MIP for selective recognition of fluconazole was evaluated by comparison with the structural analogues, miconazole, tioconazole and secnidazole, resulting in percentage recoveries of 51, 35 and 32%, respectively.

  11. Relativistic Quasiparticle Random Phase Approximation with a Separable Pairing Force

    Institute of Scientific and Technical Information of China (English)

    TIAN Yuan; MA Zhong-Yu; Ring Peter


    In our previous work [Phys. Lett. (to be published), Chin. Phys. Lett. 23 (2006) 3226], we introduced a separable pairing force for relativistic Hartree-Bogoliubov calculations. This force was adjusted to reproduce the pairing properties of the Gogny force in nuclear matter. By using the well known techniques of Talmi and Moshinsky it can be expanded in a series of separable terms and converges quickly after a few terms. It was found that the pairing properties can be depicted on almost the same footing as the original pairing interaction, not only in nuclear matter, but also in finite nuclei. In this study, we construct a relativistic quasiparticle random phase approximation (RQRPA ) with this separable pairing interaction and calculate the excitation energies of the first excited 2+ .states and reduced B(E2; 0+ → 2+) transition rates for a chain of Sn isotopes in RQRPA. Compared with the results of the full Gogny force, we find that this simple separable pairing interaction can describe the pairing properties of the excited vibrational states as well as the original pairing interaction.

  12. A theory of phase separation in asphaltene-micellar solutions

    Energy Technology Data Exchange (ETDEWEB)

    Pacheco Sanchez, Juan H. [Instituto Mexicano del Petroleo, Mexico D.F. (Mexico)


    A theory of phase separation in micellar solutions of asphaltene in aromatic hydrocarbons was reported in this paper, based on both the approach of the phase behavior of amphiphile/water micelles, and the self-association of asphaltene in aromatic core. Several experimental techniques have been used by different investigators showing the existence of some kind of critical micellar concentration (CMC) on asphaltenes in aromatic solutions. So, at least asphaltene-monomer and asphaltene-micellar phases are experimentally demonstrated facts. These two phases are the main purpose in this report on a theoretical model. Some results show the temperature versus asphaltene concentration phase diagram. The phase diagram is examined against the limited critical micelle concentration data for asphaltenes-in-toluene systems. Such phase diagram is also qualitatively examined against an experimental demonstration of phase separation. The asphaltene-micelle growth depends on the parameter K responsible for the shape and size of it. At the same time, parameter K depends on both the number of asphaltene-monomer associated in the asphaltene-micelle, and the chemical potentials in the interior and in the periphery of the micelle. An expression for getting the number of asphaltene-monomers self-associated in the asphaltene-micelle was obtained. [Spanish] Se reporta una teoria de separacion de fases en soluciones micelares de asfalteno en hidrocarburos aromaticos, basada tanto en la conducta de fase de micelas formadas por anififilos en agua como en la autoasociacion de asfaltenos en nucleos aromaticos. Se han usado diversas tecnicas experimentales por diferentes investigadores que demuestran la existancia de algun tipo de concentracion micelar critica (CMC) de soluciones de asfaltenos en aromaticos. Entonces, al menos las fases de asfalteno-monomerico y de asfalteno-micelar son hechos experimentalmente demostrados. Esta dos fases son el principal proposito de este reporte en un modelo

  13. Nanopatterns by phase separation of patterned mixed polymer monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Huber, Dale L; Frischknecht, Amalie


    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).

  14. Polymer-induced phase separation in suspensions of bacteria (United States)

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


    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.

  15. The Evidence of Phase Separation in Perovskite Manganites Above Tc

    Institute of Scientific and Technical Information of China (English)

    TIAN Hong-wei; ZANG Jian-Feng; DING Tao; ZHENG Wei-tao; WANG Xin


    A series of bulk ceramic samples of La1-xCaxMnO3 and Y1-xCaxMnO3 was prepared by the conventional solid state reaction method,and the samples of x=1/3 were investigated particularly.The colossal magnetoresistance phenomenon and the properties of magnetic and transport were studied in detail by the experiments of magnetic susceptibility and low temperature resistance.Small angle X-ray scattering (SAXS) was used to investigate the charge inhomogeneities in our samples at room temperature for the first time,and phase separation and colossal magnetoresistance phenomena induced by charge inhomogeneities above Tc were discovered.

  16. Flow Rate of He Ⅱ Liquid-Vapor Phase Separator

    Institute of Scientific and Technical Information of China (English)

    Xingen YU; Qing LI; Qiang LI; Zhengyu LI


    Experimental results are presented for superfluld (He Ⅱ) flow through porous plug liquid-vapor phase separators.Tests have been performed on seven porous plugs with different thicknesses or different permeabilities. The temperature was measured from 1.5K to 1.9K. Two flow regions were observed in small and large pressure and temperature differences regions respectively. The experimental data are compared with theoretical predictions.The performance and applicability of the basic theory are discussed. Hysteresis of the flow rate is also observed and discussed.

  17. Colossal magnetoresistance and phase separation in manganite thin films (United States)

    Srivastava, M. K.; Agarwal, V.; Kaur, A.; Singh, H. K.


    In the present work, polycrystalline Sm0.55Sr0.45MnO3 thin films were prepared on LSAT (001) single crystal substrates by ultrasonic nebulized spray pyrolysis technique. The X-ray diffraction θ-2θ scan reveals that these films (i) have very good crystallinity, (ii) are oriented along out-of-plane c-direction, and (iii) are under small tensile strain. The impact of oxygen vacancy results into (i) higher value of paramagnetic insulator (PMI) to ferromagnetic metal (FMM) transition temperature, i.e., TC/TIM, (ii) sharper PMI-FMM transition, (iii) higher value of magnetization and magnetic saturation moment, and (iv) higher value of magnetoresistance (˜99%). We suggest here that oxygen vacancy favors FMM phase while oxygen vacancy annihilation leads to antiferromagnetic-charge ordered insulator (AFM-COI) phase. The observed results have been explained in context of phase separation (PS) caused by different fractions of the competing FMM and AFM-COI phases.

  18. A study of phase separation in ternary alloys

    Indian Academy of Sciences (India)

    Saswata Bhattacharyya; T A Abinandanan


    We have studied the evolution of microstructure when a disordered ternary alloy is quenched into a ternary miscibility gap. We have used computer simulations based on multicomponent Cahn–Hilliard (CH) equations for A and B, the compositions (in mole fraction) of A and B, respectively. In this work, we present our results on the effect of relative interfacial energies on the temporal evolution of morphologies during spinodal phase separation of an alloy with average composition, A = 1/4, B = 1/4 and A = 1/2. Interfacial energies between the ‘A’ rich, ‘B’ rich and ‘C’ rich phases are varied by changing the gradient energy coefficients. The phases associated with a higher interfacial energy are found to be more rounded than those with lower energy. Further, the kinetic paths (i.e. the history of A-rich, B-rich and C-rich regions in the microstructure) are also affected significantly by the relative interfacial energies of the three phases.

  19. Properties of phase separation method synthesized superhydrophobic polystyrene films

    Energy Technology Data Exchange (ETDEWEB)

    Aruna, S.T., E-mail: [Surface Engineering Division, Council of Scientific and Industrial Research - National Aerospace Laboratories, Post Bag No. 1779, Bangalore 560 017 (India); Binsy, P.; Richard, Edna; Basu, Bharathibai J. [Surface Engineering Division, Council of Scientific and Industrial Research - National Aerospace Laboratories, Post Bag No. 1779, Bangalore 560 017 (India)


    Polystyrene (PS) based superhydrophobic films were prepared by non-solvent induced phase separation method using tetrahydrofuran (THF) as the solvent and different alcohols as non-solvents. Flory Huggins interaction parameter values of different alcohols and acetone with PS were calculated to qualify them as non-solvents for phase separation. The films were characterized using contact angle analyser, field emission scanning electron microscope, surface roughness profilometer, IR spectrometer and Raman spectrometer. The coatings exhibited a maximum water contact angle (WCA) of 159 Degree-Sign and a sliding angle (SA) < 2 Degree-Sign . With increase in the vol% of non-solvent, WCA increased and SA decreased. The microstructures of the films varied with the vol% of non-solvent and the amount of PS. The work of adhesion of PS films decreased with increasing WCA. The Raman spectral studies showed isotactic to atactic transformation of PS with the addition of non-solvents and these results corroborated well with the IR spectral studies.

  20. Correlated lateral phase separations in stacks of lipid membranes

    Energy Technology Data Exchange (ETDEWEB)

    Hoshino, Takuma, E-mail: [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Tel Aviv 69978 (Israel); Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China); Komura, Shigeyuki, E-mail: [Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China); Andelman, David, E-mail: [Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, Ramat Aviv, Tel Aviv 69978 (Israel); Kavli Institute for Theoretical Physics China, CAS, Beijing 100190 (China)


    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.

  1. Controlled topological transitions in thin film phase separation

    CERN Document Server

    Hennessy, Matthew G; Goriely, Alain; Münch, Andreas; Wagner, Barbara


    In this paper the evolution of a binary mixture in a thin-film geometry with a wall at the top and bottom is considered. By bringing the mixture into its miscibility gap so that no spinodal decomposition occurs in the bulk, a slight energetic bias of the walls towards each one of the constituents ensures the nucleation of thin boundary layers that grow until the constituents have moved into one of the two layers. These layers are separated by an interfacial region where the composition changes rapidly. Conditions that ensure the separation into two layers with a thin interfacial region are investigated based on a phase-field model. Using matched asymptotic expansions a corresponding sharp-interface problem for the location of the interface is established. It is then argued that this newly created two-layer system is not at its energetic minimum but destabilizes into a controlled self-replicating pattern of trapezoidal vertical stripes by minimizing the interfacial energy between the phases while conserving th...

  2. Phase separation like dynamics during Myxococcus xanthus fruiting body formation (United States)

    Liu, Guannan; Thutupalli, Shashi; Wigbers, Manon; Shaevitz, Joshua


    Collective motion exists in many living organisms as an advantageous strategy to help the entire group with predation, forage, and survival. However, the principles of self-organization underlying such collective motions remain unclear. During various developmental stages of the soil-dwelling bacterium, Myxococcus xanthus, different types of collective motions are observed. In particular, when starved, M. xanthus cells eventually aggregate together to form 3-dimensional structures (fruiting bodies), inside which cells sporulate in response to the stress. We study the fruiting body formation process as an out of equilibrium phase separation process. As local cell density increases, the dynamics of the aggregation M. xanthus cells switch from a spatio-temporally random process, resembling nucleation and growth, to an emergent pattern formation process similar to a spinodal decomposition. By employing high-resolution microscopy and a video analysis system, we are able to track the motion of single cells within motile collective groups, while separately tuning local cell density, cell velocity and reversal frequency, probing the multi-dimensional phase space of M. xanthus development.

  3. Phase-separation models for swimming enhancement in complex fluids

    CERN Document Server

    Man, Yi


    Swimming cells often have to self-propel through fluids displaying non-Newtonian rheology. While past theoretical work seems to indicate that stresses arising from complex fluids should systematically hinder low-Reynolds number locomotion, experimental observations suggest that locomotion enhancement is possible. In this paper we propose a physical mechanism for locomotion enhancement of microscopic swimmers in a complex fluid. It is based on the fact that micro-structured fluids will generically phase-separate near surfaces, leading to the presence of low-viscosity layers which promote slip and decrease viscous friction near the surface of the swimmer. We use two models to address the consequence of this phase separation: a nonzero apparent slip length for the fluid and then an explicit modeling of the change of viscosity in a thin layer near the swimmer. Considering two canonical setups for low-Reynolds number locomotion, namely the waving locomotion of a two-dimensional sheet and that of a three-dimensiona...

  4. The mechanical properties of phase separated protein droplets (United States)

    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.

  5. Controlled Topological Transitions in Thin-Film Phase Separation

    KAUST Repository

    Hennessy, Matthew G.


    © 2015 Society for Industrial and Applied Mathematics. In this paper the evolution of a binary mixture in a thin-film geometry with a wall at the top and bottom is considered. By bringing the mixture into its miscibility gap so that no spinodal decomposition occurs in the bulk, a slight energetic bias of the walls toward each one of the constituents ensures the nucleation of thin boundary layers that grow until the constituents have moved into one of the two layers. These layers are separated by an interfacial region where the composition changes rapidly. Conditions that ensure the separation into two layers with a thin interfacial region are investigated based on a phase-field model. Using matched asymptotic expansions a corresponding sharp-interface problem for the location of the interface is established. It is then argued that this newly created two-layer system is not at its energetic minimum but destabilizes into a controlled self-replicating pattern of trapezoidal vertical stripes by minimizing the interfacial energy between the phases while conserving their area. A quantitative analysis of this mechanism is carried out via a thin-film model for the free interfaces, which is derived asymptotically from the sharp-interface model.

  6. Phase separating colloid polymer mixtures in shear flow

    Energy Technology Data Exchange (ETDEWEB)

    Derks, Didi; Imhof, Arnout [Soft Condensed Matter, Debye Institute, Utrecht University, Princetonplein 5, 3584 CC Utrecht (Netherlands); Aarts, Dirk G A L [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, Oxford University, South Parks Road, Oxford OX1 3QZ (United Kingdom); Bonn, Daniel [Laboratoire de Physique Statistique, Ecole Normale Superieure, 24 rue Lhomond, 75231 Paris cedex 05 (France)], E-mail:


    We study the process of phase separation of colloid polymer mixtures in the (spinodal) two-phase region of the phase diagram in shear flow. We use a counter-rotating shear cell and image the system by means of confocal laser scanning microscopy. The system is quenched from an initially almost homogeneous state at very high (200 s{sup -1}) shear rate to a low shear rate {gamma}-dot. A spinodal decomposition pattern is observed. Initially, the characteristic length scale increases linearly with time. As the structure coarsens, the shear imposes a certain length scale on the structure and a clear asymmetry develops. The domains become highly stretched along the flow direction, and the domain width along the vorticity axis reaches a stationary size, which scales as approx. {gamma}-do{sup -0.35}. Furthermore, on quenching from an intermediate (6.7 s{sup -1}) to a low shear rate the elongated structures become Rayleigh unstable and break up into smaller droplets. Still, the system eventually reaches the same steady state as was found from a direct high to low shear rate quench through coarsening.

  7. Dual Phase Membrane for High Temperature CO2 Separation

    Energy Technology Data Exchange (ETDEWEB)

    Jerry Lin


    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

  8. Formulation of Synthesized Zinc Oxide Nanopowder into Hybrid Beads for Dye Separation

    Directory of Open Access Journals (Sweden)

    H. Shokry Hassan


    Full Text Available The sol-gel prepared zinc oxide nanopowder was immobilized onto alginate-polyvinyl alcohol polymer blend to fabricate novel biocomposite beads. Various physicochemical characterization techniques have been utilized to identify the crystalline, morphological, and chemical structures of both the fabricated zinc oxide hybrid beads and their corresponding zinc oxide nanopowder. The thermal stability investigations demonstrate that ZnO nanopowder stability dramatically decreased with its immobilization into the polymeric alginate and PVA matrix. The formulated beads had very strong mechanical strength and they are difficult to be broken up to 1500 rpm. Moreover, these hybrid beads are chemically stable at the acidic media (pH < 7 especially within the pH range of 2–7. Finally, the applicability of the formulated ZnO hybrid beads for C.I. basic blue 41 (BB41 decolorization from aqueous solution was examined.

  9. Computational investigation of porous media phase field formulations: Microscopic, effective macroscopic, and Langevin equations (United States)

    Ververis, Antonios; Schmuck, Markus


    We consider upscaled/homogenized Cahn-Hilliard/Ginzburg-Landau phase field equations as mesoscopic formulations for interfacial dynamics in strongly heterogeneous domains such as porous media. A recently derived effective macroscopic formulation, which takes systematically the pore geometry into account, is computationally validated. To this end, we compare numerical solutions obtained by fully resolving the microscopic pore-scale with solutions of the upscaled/homogenized porous media formulation. The theoretically derived convergence rate O (ɛ 1 / 4) is confirmed for circular pore-walls. An even better convergence of O (ɛ1) holds for square shaped pore-walls. We also compute the homogenization error over time for different pore geometries. We find that the quality of the time evolution shows a complex interplay between pore geometry and heterogeneity. Finally, we study the coarsening of interfaces in porous media with computations of the homogenized equation and the microscopic formulation fully resolving the pore space. We recover the experimentally validated and theoretically rigorously derived coarsening rate of O (t 1 / 3) in the periodic porous media setting. In the case of critical quenching and after adding thermal noise to the microscopic porous media formulation, we observe that the influence of thermal fluctuations on the coarsening rate shows after a short, expected phase of universal coarsening, a sharp transition towards a different regime.

  10. Technical Note: Simple formulations and solutions of the dual-phase diffusive transport for biogeochemical modeling

    Directory of Open Access Journals (Sweden)

    J. Y. Tang


    Full Text Available Representation of gaseous diffusion in variably saturated near-surface soils is becoming more common in land biogeochemical models, yet the formulations and numerical solution algorithms applied vary widely. We present three different but equivalent formulations of the dual-phase (gaseous and aqueous tracer diffusion transport problem that is relevant to a wide class of volatile tracers in land biogeochemical models. Of these three formulations (i.e., the gas-primary, aqueous-primary, and bulk tracer based formulations, we contend the gas-primary formulation is the most convenient for modeling tracer dynamics in biogeochemical models. We then provide finite volume approximation to the gas-primary equation and evaluate its accuracy against three analytical models: one for steady-state soil CO2 dynamics, one for steady-state soil CO2 dynamics, and one for transient tracer diffusion from a constant point source into two different sequentially aligned medias. All evaluations demonstrated good accuracy of the numerical approximation. We expect our result will standardize an efficient mechanistic numerical method for solving relatively simple, multi-phase, one-dimensional diffusion problems in land models.


    National Research Council Canada - National Science Library

    Hajivand, P; Vaziri, A


    Abstract In this study, various water-soluble and oil-soluble demulsifiers were selected for separation of water from crude oil emulsions and their productivity measured using the Bottle-test method at 70...

  12. Intelligent System for Diagnosis of a Three-Phase Separator

    Directory of Open Access Journals (Sweden)

    Irina Ioniţă


    Full Text Available Intelligent systems for diagnosis have been used in a variety of domains: financial evaluation, credit scoring problem, identification of software and hardware problems of mechanical and electronic equipment, medical diagnosis, fault detection in gas-oil production plants etc. The goal of diagnosis systems is to classify the observed symptoms as being caused by some diagnosis class while advising systems perform such a classification and offer corrective remedies (recommendations. The current paper discuss the opportunity to combine more intelligent techniques and methodologies (intelligent agents, data mining and expert systems to increase the accuracy of results obtained from the diagnosis of a three-phase separator. The results indicate that the diagnosis hybrid system benefits from the advantages of each module component: intelligent agent module, data mining module and expert system module.

  13. Intelligent System for Diagnosis of a Three-Phase Separator

    Directory of Open Access Journals (Sweden)

    Irina Ioniţă


    Full Text Available Intelligent systems for diagnosis have been used in a variety of domains: financial evaluation, credit scoring problem, identification of software and hardware problems of mechanical and electronic equipment, medical diagnosis, fault detection in gas-oil production plants etc. The goal of diagnosis systems is to classify the observed symptoms as being caused by some diagnosis class while advising systems perform such a classification and offer corrective remedies (recommendations. The current paper discuss the opportunity to combine more intelligent techniques and methodologies (intelligent agents, data mining and expert systems to increase the accuracy of results obtained from the diagnosis of a three-phase separator. The results indicate that the diagnosis hybrid system benefits from the advantages of each module component: intelligent agent module, data mining module and expert system module.

  14. Theoretical and Computational Studies of Three-dimensional Phase Separation (United States)

    Wang, K. G.


    The diffusive interactions occurring within a population of precipitates dispersed throughout a contiguous matrix may be described on the basis of a diffusion screening length. Screening theory predicts as functions of the dispersoid volume fraction the changes in diffusion screening length, maximum particle size, coarsening rate, and the scaled particle-size distribution. Furthermore, by considering fluctuations observed in the growth rates of individual particles, we report on developments of a stochastic theory of phase separation. Also, particle-size distributions and the maximum particle radii predicted as a function of time from theory and simulations are shown to agree well with experimental results obtained from measurements performed on Al3Li precipitates in binary Al-Li alloys. Lastly, we calculated the spatial correlation function of these microstructures. We revealed through data analysis the relationship between the critical length scale for diffusion-mediated coarsening and spatial correlations in the microstructure.

  15. Vibration response of a pipe subjected to two-phase flow: Analytical formulations and experiments

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz-Vidal, L. Enrique, E-mail: [Department of Mechanical Engineering, Sao Carlos School of Engineering, University of Sao Paulo (USP), Av., Trabalhador São-carlense, 400, 13566-970 São Carlos, SP (Brazil); Mureithi, Njuki W., E-mail: [Department of Mechanical Engineering, Polytechnique Montreal, Département de Géniemécanique 2900, H3T 1J7 Montreal, QC (Canada); Rodriguez, Oscar M.H., E-mail: [Department of Mechanical Engineering, Sao Carlos School of Engineering, University of Sao Paulo (USP), Av., Trabalhador São-carlense, 400, 13566-970 São Carlos, SP (Brazil)


    Highlights: • Analytical formulations for two-phase flow-induced vibration (2-FIV) are presented. • Standard deviation of acceleration pipe response is a function of the square of shear velocity. • Peak frequency is correlated to hydrodynamic mass and consequently to void fraction. • Dynamic pipe response increases with increasing mixture velocity and void fraction. • Hydrodynamic mass in 2-FIV in horizontal pipe is proportional to mixture density. - Abstract: This paper treats the two-phase flow-induced vibration in pipes. A broad range of two-phase flow conditions, including bubbly, dispersed and slug flow, were tested in a clamped-clamped straight horizontal pipe. The vibration response of both transversal directions for two span lengths was measured. From experimental results, an in-depth discussion on the nature of the flow excitation and flow-parameters influence is presented. The hydrodynamic mass parameter is also studied. Experimental results suggest that it is proportional to mixture density. On the other hand, two analytical formulations were developed and tested against experimental results. One formulation predicts the quadratic trend between standard deviation of acceleration and shear velocity found in experiments. The other formulation indicates that the peak-frequency of vibration response depends strongly on void fraction. It provides accurate predictions of peak-frequency, predicting 97.6% of the data within ±10% error bands.

  16. Estimation of Chlorpyriphos in its Formulation (Paraban 20% EC by Reversed-Phase HPLC

    Directory of Open Access Journals (Sweden)

    Deepti Joshi


    Full Text Available A method has been developed for estimation of active ingredient in chlorpyriphos formulation (Paraban 20% EC. The formulation was extracted in chloroform, dried and resuspended in acetonitrile. The cleanup was performed using C18 SPE cartridge. The active ingredient was estimated using 5 μm ODS-II column, mobile phase was acetonitrile: water (75:25 v/v and detection at 229nm. The efficiency of clean up method was found to be 95% and minimum limit of detection < 2.5ng. The detector response was linear with in concentration range 2.5ng – 50ng at RSD 1.42%.

  17. A Temperature-Dependent Phase-Field Model for Phase Separation and Damage (United States)

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


    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 Feireisl (Comput Math Appl 53:461-490, 2007) in the framework of Fourier-Navier-Stokes systems and then recently employed in Feireisl et al. (Math Methods Appl Sci 32:1345-1369, 2009) and Rocca and 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.

  18. Diffusion-limited phase separation in eukaryotic chemotaxis (United States)

    Gamba, Andrea; de Candia, Antonio; Di Talia, Stefano; Coniglio, Antonio; Bussolino, Federico; Serini, Guido


    The ability of cells to sense spatial gradients of chemoattractant factors governs the development of complex eukaryotic organisms. Cells exposed to shallow chemoattractant gradients respond with strong accumulation of the enzyme phosphatidylinositol 3-kinase (PI3K) and its D3-phosphoinositide product (PIP3) on the plasma membrane side exposed to the highest chemoattractant concentration, whereas PIP3-degrading enzyme PTEN and its product PIP2 localize in a complementary pattern. Such an early symmetry-breaking event is a mandatory step for directed cell movement elicited by chemoattractants, but its physical origin is still mysterious. Here, we propose that directional sensing is the consequence of a phase-ordering process mediated by phosphoinositide diffusion and driven by the distribution of chemotactic signal. By studying a realistic reaction–diffusion lattice model that describes PI3K and PTEN enzymatic activity, recruitment to the plasma membrane, and diffusion of their phosphoinositide products, we show that the effective enzyme–enzyme interaction induced by catalysis and diffusion introduces an instability of the system toward phase separation for realistic values of physical parameters. In this framework, large reversible amplification of shallow chemotactic gradients, selective localization of chemical factors, macroscopic response timescales, and spontaneous polarization arise naturally. The model is robust with respect to order-of-magnitude variations of the parameters. PMID:16291809

  19. Nanometer-scale phase separation in colossal magnetoresistive manganite

    Energy Technology Data Exchange (ETDEWEB)

    Roessler, Sahana; Ernst, Stefan; Wirth, Steffen; Steglich, Frank [Max Planck Institute for Chemical Physics of Solids, Noethnizer Strasse 40, 01187, Dresden (Germany); Padmanabhan, B.; Elizabeth, Suja; Bhat, H.L. [Department of Physics, Indian Institute of Science, Bangalore 560012 (India)


    In strongly correlated electron systems an intrinsic instability of the electronic state and competing long-range interactions may result in the formation of nanometer-sized regions of different phases. We have carried out scanning tunneling microscopy/spectroscopy on single crystals of a colossal magnetoresistive manganite Pr{sub 0.68}Pb{sub 0.32}MnO{sub 3} at different temperatures in order to probe their spatial homogeneity across the metal-insulator transition temperature T{sub M-I}. In this compound, the Curie temperature T{sub C} is lower than T{sub M-I}. Spectroscopic studies revealed inhomogeneous maps of the zero-bias conductance with small patches of metallic clusters on a length scale of 2-3 nm only within a narrow temperature range close to the metal-insulator transition. A detailed analysis of conductance histograms based on these maps gave direct evidence for phase separation into insulating and metallic regions in the paramagnetic metallic state, i.e. for T{sub C} T{sub M-I}.

  20. Micro-phase Separation via Spinodal-like Decomposition in Hexamethylynediisocyanate (HDI)-polyurea

    Energy Technology Data Exchange (ETDEWEB)

    Kulkarni, Amit S. [SABIC Innovative Plastics, Mt. Vernon, IN (United States); Beaucage, Gregory [Univ. of Cincinnati, OH (United States); Wilkes, Garth L. [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Das, Sudipto [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Yilgor, Iskander [Koc Univ., Istanbul (Turkey)


    We found that micro-phase separation in hexamethylynediisocyanate-polyurea was studied using small-angle X-ray scattering and infrared absorption. Moreover, it was found that phase separation in this system followed spinodal-like decomposition on a 3–4 nm size scale with phase separation occuring on a time scale of days.

  1. A new approach to network heterogeneity: Polymerization Induced Phase Separation in photo-initiated, free-radical methacrylic systems. (United States)

    Szczepanski, Caroline R; Pfeifer, Carmem S; Stansbury, Jeffrey W


    Non-reactive, thermoplastic prepolymers (poly- methyl, ethyl and butyl methacrylate) were added to a model homopolymer matrix composed of triethylene glycol dimethacrylate (TEGDMA) to form heterogeneous networks via polymerization induced phase separation (PIPS). PIPS creates networks with distinct phase structure that can partially compensate for volumetric shrinkage during polymerization through localized internal volume expansion. This investigation utilizes purely photo-initiated, free-radical systems, broadening the scope of applications for PIPS since these processing conditions have not been studied previously.The introduction of prepolymer into TEGDMA monomer resulted in stable, homogeneous monomer formulations, most of which underwent PIPS upon photo-irradiation, creating heterogeneous networks. During polymerization the presence of prepolymer enhanced autoacceleration, allowing for a more extensive ambient cure of the material. Phase separation, as characterized by dynamic changes in sample turbidity, was monitored simultaneously with monomer conversion and either preceded or was coincident with network gelation. Dynamic mechanical analysis shows a broadening of the tan delta peak and secondary peak formation, characteristic of phase-separated materials, indicating one phase rich in prepolymer and another depleted form upon phase separation. In certain cases, PIPS leads to an enhanced physical reduction of volumetric shrinkage, which is attractive for many applications including dental composite materials.

  2. Comparison of liquid and supercritical fluid chromatography mobile phases for enantioselective separations on polysaccharide stationary phases. (United States)

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


    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.

  3. CDS Simulation and Pattern Formation of Phase Separation

    Institute of Scientific and Technical Information of China (English)

    ZhangjiLIU; MenCHENG; 等


    Several properties of the generation and evolution of phase separating patterns for binary material studied by CDS model are proposed.The main conclusions are(1) for alloys spinodal decomposition,the conceptions of “macro-pattern” and “micropattern” are posed by “black-and-white graph”and “gray-scale graph” respectively.We find that though the four forms of map f that represent the self-evolution of order parameter in a cell (lattice)are similar to each other in “macro-pattern”,there are evident differences in their micro-pattern,e.g.,some different fine netted sturctures in the black domain and the white domain are found by the that distinct mechanical and physical behaviors shall be obtained.(2) If the two constituteons of block copolymers are not symmetric (i.e.r≠0.5),a pattern called “grain-strip cross pattern is discovered,is the 0.43

  4. Confinement-Driven Phase Separation of Quantum Liquid Mixtures (United States)

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


    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.

  5. Electrospun Polymer Blend Nanofibers for Tunable Drug Delivery: The Role of Transformative Phase Separation on Controlling the Release Rate. (United States)

    Tipduangta, Pratchaya; Belton, Peter; Fábián, László; Wang, Li Ying; Tang, Huiru; Eddleston, Mark; Qi, Sheng


    Electrospun fibrous materials have a wide range of biomedical applications, many of them involving the use of polymers as matrices for incorporation of therapeutic agents. The use of polymer blends improves the tuneability of the physicochemical and mechanical properties of the drug loaded fibers. This also benefits the development of controlled drug release formulations, for which the release rate can be modified by altering the ratio of the polymers in the blend. However, to realize these benefits, a clear understanding of the phase behavior of the processed polymer blend is essential. This study reports an in depth investigation of the impact of the electrospinning process on the phase separation of a model partially miscible polymer blend, PVP K90 and HPMCAS, in comparison to other conventional solvent evaporation based processes including film casting and spin coating. The nanoscale stretching and ultrafast solvent removal of electrospinning lead to an enhanced apparent miscibility between the polymers, with the same blends showing micronscale phase separation when processed using film casting and spin coating. Nanoscale phase separation in electrospun blend fibers was confirmed in the dry state. Rapid, layered, macroscale phase separation of the two polymers occurred during the wetting of the fibers. This led to a biphasic drug release profile from the fibers, with a burst release from PVP-rich phases and a slower, more continuous release from HPMCAS-rich phases. It was noted that the model drug, paracetamol, had more favorable partitioning into the PVP-rich phase, which is likely to be a result of greater hydrogen bonding between PVP and paracetamol. This led to higher drug contents in the PVP-rich phases than the HPMCAS-rich phases. By alternating the proportions of the PVP and HPMCAS, the drug release rate can be modulated.

  6. Electromagnetic separation of primary iron-rich phases from aluminum-silicon melt

    Institute of Scientific and Technical Information of China (English)

    李天晓; 许振明; 孙宝德; 疏达; 周尧和


    The difference of conductivity between primary iron-rich phases and aluminum melt has been used toseparate them by electromagnetic force (EMF) which is induced by imposing a direct electric current and a steadymagnetic field in molten Al-Si alloy. Theoretical analysis and experiments on self-designed electromagnetic separa-tion indicates that primary needle-like β phases are difficult to separate; while primary a iron-rich phases can be sepa-rated by electromagnetic separation. Primary iron-rich phases have been removed from the melt successfully whenthe molten metal flows horizontally through separation channel. The iron content is reduced from 1.13% to 0.41%.

  7. A hybrid formulation for the numerical simulation of condensed phase explosives (United States)

    Michael, L.; Nikiforakis, N.


    In this article we present a new formulation and an associated numerical algorithm, for the simulation of combustion and transition to detonation of condensed-phase commercial- and military-grade explosives, which are confined by (or in general interacting with one or more) compliant inert materials. Examples include confined rate-stick problems and interaction of shock waves with gas cavities or solid particles in explosives. This formulation is based on an augmented Euler approach to account for the mixture of the explosive and its products, and a multi-phase diffuse interface approach to solve for the immiscible interaction between the mixture and the inert materials, so it is in essence a hybrid (augmented Euler and multi-phase) model. As such, it has many of the desirable features of the two approaches and, critically for our applications of interest, it provides the accurate recovery of temperature fields across all components. Moreover, it conveys a lot more physical information than augmented Euler, without the complexity of full multi-phase Baer-Nunziato-type models or the lack of robustness of augmented Euler models in the presence of more than two components. The model can sustain large density differences across material interfaces without the presence of spurious oscillations in velocity and pressure, and it can accommodate realistic equations of state and arbitrary (pressure- or temperature-based) reaction-rate laws. Under certain conditions, we show that the formulation reduces to well-known augmented Euler or multi-phase models, which have been extensively validated and used in practice. The full hybrid model and its reduced forms are validated against problems with exact (or independently-verified numerical) solutions and evaluated for robustness for rate-stick and shock-induced cavity collapse case-studies.

  8. Bottlenecks in the development of topical analgesics: molecule, formulation, dose-finding, and phase III design

    Directory of Open Access Journals (Sweden)

    Keppel Hesselink JM


    Full Text Available Jan M Keppel Hesselink,1 David J Kopsky,2 Stephen M Stahl3 1Institute Neuropathic Pain, Bosch en Duin, the Netherlands; 2Institute Neuropathic Pain, Amsterdam, the Netherlands; 3University of California San Diego, La Jolla, CA, USA Abstract: Topical analgesics can be defined as topical formulations containing analgesics or co-analgesics. Since 2000, interest in such formulations has been on the rise. There are, however, four critical issues in the research and development phases of topical analgesics: 1 The selection of the active pharmaceutical ingredient. Analgesics and co-analgesics differ greatly in their mechanism of action, and it is required to find the most optimal fit between such mechanisms of action and the pathogenesis of the targeted (neuropathic pain. 2 Issues concerning the optimized formulation. For relevant clinical efficacy, specific characteristics for the selected vehicle (eg, cream base or gel base are required, depending on the physicochemical characteristics of the active pharmaceutical ingredient(s to be delivered. 3 Well-designed phase II dose-finding studies are required, and, unfortunately, such trials are missing. In fact, we will demonstrate that underdosing is one of the major hurdles to detect meaningful and statistically relevant clinical effects of topical analgesics. 4 Selection of clinical end points and innovatively designed phase III trials. End point selection can make or break a trial. For instance, to include numbness together with tingling as a composite end point for neuropathic pain seems stretching the therapeutic impact of an analgesic too far. Given the fast onset of action of topical analgesics (usually within 30 minutes, enrichment designs might enhance the chances for success, as the placebo response might decrease. Topical analgesics may become promising inroads for the treatment of neuropathic pain, once sufficient attention is given to these four key aspects. Keywords: topical, analgesics

  9. Convergent Bayesian formulations of blind source separation and electromagnetic source estimation

    CERN Document Server

    Knuth, Kevin H


    We consider two areas of research that have been developing in parallel over the last decade: blind source separation (BSS) and electromagnetic source estimation (ESE). BSS deals with the recovery of source signals when only mixtures of signals can be obtained from an array of detectors and the only prior knowledge consists of some information about the nature of the source signals. On the other hand, ESE utilizes knowledge of the electromagnetic forward problem to assign source signals to their respective generators, while information about the signals themselves is typically ignored. We demonstrate that these two techniques can be derived from the same starting point using the Bayesian formalism. This suggests a means by which new algorithms can be developed that utilize as much relevant information as possible. We also briefly mention some preliminary work that supports the value of integrating information used by these two techniques and review the kinds of information that may be useful in addressing the...

  10. Continuous Hydrolysis and Liquid–Liquid Phase Separation of an Active Pharmaceutical Ingredient Intermediate Using a Miniscale Hydrophobic Membrane Separator

    DEFF Research Database (Denmark)

    Cervera Padrell, Albert Emili; Morthensen, Sofie Thage; Lewandowski, Daniel Jacob


    Continuous hydrolysis of an active pharmaceutical ingredient intermediate, and subsequent liquid–liquid (L-L) separation of the resulting organic and aqueous phases, have been achieved using a simple PTFE tube reactor connected to a miniscale hydrophobic membrane separator. An alkoxide product...... a PTFE membrane with 28 cm2 of active area. A less challenging separation of water and toluene was achieved at total flow rates as high as 80 mL/min, with potential to achieve even higher flow rates. The operability and flexibility of the membrane separator and a plate coalescer were compared...

  11. Long range correlations generated by phase separation. Exact results from field theory

    Energy Technology Data Exchange (ETDEWEB)

    Delfino, Gesualdo [SISSA,Via Bonomea 265, 34136 Trieste (Italy); INFN - sezione di Trieste (Italy); Squarcini, Alessio [Max-Planck-Institut für Intelligente Systeme,Heisenbergstr. 3, D-70569 Stuttgart (Germany); IV. Institut für Theoretische Physik, Universität Stuttgart,Pfaffenwaldring 57, D-70569 Stuttgart (Germany)


    We consider near-critical planar systems with boundary conditions inducing phase separation. While order parameter correlations decay exponentially in pure phases, we show by direct field theoretical derivation how phase separation generates long range correlations in the direction parallel to the interface, and determine their exact analytic form. The latter leads to specific contributions to the structure factor of the interface.

  12. Interplay between gelation and phase separation in aqueous solutions of methylcellulose and hydroxypropylmethylcellulose. (United States)

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


    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".

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

    Energy Technology Data Exchange (ETDEWEB)

    Koster, J.P.; Nagler, S.E.; Adams, E.D. [Florida Univ., Gainesville, FL (United States). Dept. of Physics; Wignall, G.D. [Oak Ridge National Lab., TN (United States). Solid State Div.


    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.

  14. Dynam ic electrom agnetic separation of iron-rich phase inclusions from A lalloy

    Directory of Open Access Journals (Sweden)

    Yu Hai-jun


    Full Text Available Electrom agnetic separation ofthe iron-rich phase inclusions from A lalloy w as investigated. The influencing param eters including m agnetic induction density,the section shape of the separating channeland the length ofinfluentialloop ofthe m etalm elton the separation efficiency of iron-rich phase inclusions were studied. The results show that when the proper magnetic induction density (B =0.3T is applied,rectangle separating channelis used,and the influentialloopof the metal melt is long, high separating efficiency of the iron-rich phase inclusions can be obtained.

  15. Reversed-phase HPLC method for the estimation of acetaminophen, ibuprofen and chlorzoxazone in formulations. (United States)

    Ravisankar, S; Vasudevan, M; Gandhimathi, M; Suresh, B


    A simple, precise and rapid reversed-phase HPLC method was developed for the simultaneous estimation of acetaminophen, ibuprofen and chlorzoxazone in formulations. The method was carried out on a Kromasil(R) C(8) column using a mixture of 0.2% triethylamine:acetonitrile (adjusted to pH 3.2 using dilute orthophosphoric acid), and detection was carried out at 215 nm using ketoprofen as internal standard. All these drugs showed linearity in the range of 2-10 mug ml(-1), and limits of quantification was found to be 10, 50 and 20 ng ml(-1) for acetaminophen, ibuprofen and chlorzoxazone, respectively.

  16. Effects of mobile vacancies on the dynamics of ordering and phase separation in nonconserved multicomponent systems

    DEFF Research Database (Denmark)

    Gilhøj, Henriette; Jeppesen, Claus; Mouritsen, Ole G.


    The effects of mobile vacancies on the dynamics of ordering processes and phase separation in multicomponent systems are studied via Monte Carlo simulations of a two-dimensional seven-state ferromagnetic Potts model with varying degrees of site dilution. The model displays phase equilibria...... corresponding to a dilute Potts-disordered (fluid) phase and a dilute Potts-ordered phase (solid), as well as a broad region of coexistence between the fluid and the solid phase. Temperature quenches into the dilute Potts-ordered phase as well as into the phase-separated region are considered under...... the condition of conserved vacancy density and nonconserved Potts order. The dynamics of ordering and phase separation is found to follow algebraic growth laws with exponent values that depend on the phase to which the quench is performed. Strong transient effects are observed in the dilute Potts-ordered phase...

  17. Rosin coacervate microcapsules: effect of solvent on phase separation of rosin. (United States)

    Sheorey, D S; Dorle, A K


    The effect of various solvent-non-solvent pairs on phase separation of rosin was studied visually and microscopically. The type of phase separated was found to be a function of viscosity of the solution rather than the dielectric constant of the solvent. Triangular phase diagrams were constructed and optimum coacervation conditions were determined. Of all the solvents tested, only ethanol and acetone yielded a coacervate phase.

  18. On separability of A-phases during the cyclic alternating pattern. (United States)

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


    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.

  19. New mechanisms for phase separation in polymer-surfactant mixtures

    NARCIS (Netherlands)

    Currie, E.P.K.; Cohen Stuart, M.A.; Borisov, O.V.


    The cooperative association of ionic surfactants with polymer chains leads to quite novel features in the phase behaviour of polymer solutions. Using an analytic mean-field model, we analyze phase equilibria in solutions of neutral polymers mixed with ionic surfactants. We predict the possibilities

  20. Phase separation and disorder in doped nematic elastomers

    KAUST Repository

    Köpf, M. H.


    We formulate and analyse a model describing the combined effect of mechanical deformation, dynamics of the nematic order parameter, and concentration inhomogeneities in an elastomeric mixture of a mesogenic and an isotropic component. The uniform nematic state may exhibit a long-wave instability corresponding to nematic-isotropic demixing. Numerical simulations starting from either a perfectly ordered nematic state or a quenched isotropic state show that coupling between the mesogen concentration and the nematic order parameter influences the shape and orientation of the domains formed during the demixing process. © EDP Sciences/ Società Italiana di Fisica/ Springer-Verlag 2013.

  1. Separations/pretreatment considerations for Hanford privatization phase 2

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  2. Two-phase (bio)catalytic reactions in a table-top centrifugal contact separator

    NARCIS (Netherlands)

    Kraai, Gerard N.; Zwol, Floris van; Schuur, Boelo; Heeres, Hero J.; Vries, Johannes G. de


    A new spin on catalysis: A table-top centrifugal contact separator allows for fast continuous two-phase reactions to be performed by intimately mixing two immiscible phases and then separating them. Such a device has been used to produce biodiesel from sunflower oil and MeOH/NaOMe. A lipase-catalyze

  3. Two-phase (bio)catalytic reactions in a table-top centrifugal contact separator

    NARCIS (Netherlands)

    Kraai, Gerard N.; Zwol, Floris van; Schuur, Boelo; Heeres, Hero J.; Vries, Johannes G. de


    A new spin on catalysis: A table-top centrifugal contact separator allows for fast continuous two-phase reactions to be performed by intimately mixing two immiscible phases and then separating them. Such a device has been used to produce biodiesel from sunflower oil and MeOH/NaOMe. A lipase-catalyze

  4. Investigation of the Influence of Sucrose and Cholesterol on the Phase Transition Temperature of nanoliposomal formulation besides using particle size Reduction Techniques (Ultrasonication/High Pressure Homogenization

    Directory of Open Access Journals (Sweden)

    Z Malaei-Balasi


    Full Text Available Introduction: The successful application of nanoliposoms as an effective drug delivery system depends on their stability in the medium. In this article, influence of additive materials such as cholesterol and sucrose besides two natural and synthesized phospholipids have been investigated. Methods: In the present study, designing and synthesis of nanoliposomal formulations were prepared using thin film method. This liposomal suspension was downsized by two methods, the high-pressure homogenizer and ultrasound to form small unilamellar vesicles. The size distributions, zeta potentials and phase transition temperature of formulations were all determined by a zetasizer and differential scanning calorimetry(DSC. In addition, the contribution of nanoliposomal formulation has been investigated by HPLC and FTIR methods. Results: Results of the DSC measurments indicated that incorporation of unsaturated phospholipid (SOY PC may cause phase separation with partial miscibility in the liposome bilayer containing of DPPG. The optimal nanoliposomal formulation was composed of (DPPC: CHOL: mPEG2000-DSPE with the mole percents equal to (83:15:2, respectively. In addition, sucrose has been used in the formulation with a total amounts six times greater than that of the lipids. The properties of optimized nanoliposome have been shown as the size average 104nm, zeta potential 8.04mv and phase transition temperature of lipid less than 37°C which were stable enough to be utilized for loading and releasing bioactives in body temperature. Conclusion: Finally the produced nanoliposomes were stable vesicles in the proper size, phase transition temperature and surface charge without any aggregation and fusion.

  5. Phase separation in fluids exposed to spatially periodic external fields. (United States)

    Vink, R L C; Archer, A J


    When a fluid is confined within a spatially periodic external field, the liquid-vapor transition is replaced by a different transition called laser-induced condensation (LIC) [Götze et al., Mol. Phys. 101, 1651 (2003)]. In d=3 dimensions, the periodic field induces an additional phase, characterized by large density modulations along the field direction. At the triple point, all three phases (modulated, vapor, and liquid) coexist. At temperatures slightly above the triple point and for low (high) values of the chemical potential, two-phase coexistence between the modulated phase and the vapor (liquid) is observed; by increasing the temperature further, both coexistence regions terminate in critical points. In this paper, we reconsider LIC using the Ising model to resolve a number of open issues. To be specific, we (1) determine the universality class of the LIC critical points and elucidate the nature of the correlations along the field direction, (2) present a mean-field analysis to show how the LIC phase diagram changes as a function of the field wavelength and amplitude, (3) develop a simulation method by which the extremely low tension of the interface between modulated and vapor or liquid phase can be measured, (4) present a finite-size scaling analysis to accurately extract the LIC triple point from finite-size simulation data, and (5) consider the fate of LIC in d=2 dimensions.

  6. Simultaneous separation and determination of process-related substances and degradation products of venlafaxine by reversed-phase HPLC. (United States)

    Nageswara Rao, R; Narasa Raju, A


    A simple and rapid gradient RP HPLC method for simultaneous separation and determination of venlafaxine and its related substances in bulk drugs and pharmaceutical formulations has been developed. As many as four process impurities and one degradation product of venlafaxine have been separated on a Kromasil KR100-5C18 (4.6 mm x 250 mm; particle size 5 microm) column with gradient elution using 0.3% diethylamine buffer (pH 3.0) and ACN/methanol (90:10 v/v) as a mobile phase. The column was maintained at 40 degrees C and the eluents were monitored with photo diode array detection at 225 nm. The chromatographic behaviour of all the compounds was examined under variable compositions of different solvents, temperatures, buffer concentrations and pH. The method was validated in terms of accuracy, precision and linearity as per ICH guidelines. The inter- and intraday assay precision was method was successfully applied to the analysis of commercial formulations and the recoveries of venlafaxine were in the range of 99.32-100.67 with %RSD method could be of use not only for rapid and routine evaluation of the quality of venlafaxine in bulk drug manufacturing units but also for the detection of its impurities in pharmaceutical formulations. Forced degradation of venlafaxine was carried out under thermal, photo, acidic, basic and peroxide conditions and the acid degradation products were characterized by ESI-MS/MS, 1H NMR and FT-IR spectral data.


    Directory of Open Access Journals (Sweden)

    Lanka Venkateswararao


    Full Text Available A novel reverse phase high performance liquid chromatographic method (RP-HPLC was developed and validated for the determination of doxofylline (DXF in pharmaceutical formulations. Agilent 1100 series HPLC instrument equipped with variable wavelength programmable UV-Visible detector and a chromosil C18 (250mm x 4.6mm, 5μm column with an auto injector was used for the present investigation. A volume of 20µL of working standard of concentration 25µg/mL was injected into the chromatographic system, the component was separated by using the mobile phase of the mixture of potassium dihydrogen phosphate buffer of pH 5.5 and acetonitrile in the ratio 75:25(v/v at a flow rate of 1.0 mL/min and the detection of the components was carried out at a wavelength of 275nm. Chemstation software was used for the data acquisition through out the analysis. The system suitable parameters such as number of theoretical plates, tailing factor and resolution were found to be satisfactory. The retention time of the component was found to be at 4.814 minutes. The proposed method was validated in terms of precision, accuracy, linearity, limit of detection, limit of quantification, robustness and ruggedness. The developed method was found to be rapid, simple and sensitive hence it could be used as an alternative method in assay of the doxofylline in any pharmaceutical industries.

  8. First-principles calculation of phase equilibria and phase separation of the Fe-Ni alloy system

    Institute of Scientific and Technical Information of China (English)

    Ying Chen; Shuichi Iwata; Tetsuo Mohri


    Theoretical investigation of the phase equilibria of the Fe-Ni alloy has been performed by combining the FLAPW total energy calculations and the Cluster Variation Method through the Cluster Expansion Method. The calculations have proved the stabilization of the L12 phase at 1:3 stoichiometry, which is in agreement with the experimental result,and predicted the existence of L10 as a stable phase below 550 K; this L10 phase has been missing in the conventional phasediagram. The calculations are extended to the Fe-rich region that is characterized by a wide range phase separation and has drawn considerable attention because of the intriguing Invar property associated with a Fe concentration of 65%. To reveal the origin of the phase separation, a P-V curve in an entire concentration range is derived by the second derivative of free energy functional of the disordered phase with respect to the volume. The calculation confirmed that the phase separation is caused by the breakdown of the mechanical-stability criterion. The newly calculated phase separation line combined with the L10 and L12 order-disordered phase boundaries provides phase equilibria in the wider concentration range of the system. Furthermore, a coefficient of thermal expansion (CTE) is attempted by incorporating the thermal vibration effect through harmonic approximation of the Debye-Gruneisen model. The Invar behavior has been reproduced, and the origin of this anomalous volume change has been discussed.

  9. Pinning of phase separation of aqueous solution of hydroxypropylmethylcellulose by gelation (United States)

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


    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.


    Institute of Scientific and Technical Information of China (English)

    Lin-li He; Lin-xi Zhang


    The phase behaviors of symmetric diblock copolymer thin films confined between two hard, parallel and diversified patterned surfaces are investigated by three-dimensional dissipative particle dynamics (DPD) simulations. The induction of diversified patterned surfaces on phase separation of symmetric diblock copolymer films in snapshots, density profiles and concentration diagrams of the simulated systems are presented. The phase separations can be controlled by the patterned surfaces. In the meantime, the mean-square end-to-end distance of the confined polymer chains (R2) is also discussed. Surface-induced phase separation for diblock copolymers can help us to create novel and controlled nanostructured materials.

  11. Effects of Concentration and Conformation of Surfactants on Phase Separation of Surfactant-Water-Oil Systems

    Institute of Scientific and Technical Information of China (English)

    袁银权; 邹宪武; 刘昊阳


    The effects of surfactants on the phase separation of surfactant-water-oil systems have been investigated by using discontinuous molecular dynamic simulations. The phase separation speed and equilibrium configuration are dependent on the surfactant concentration and conformation. The equilibrium concentration of surfactants at the interface remains constant. With the increasing surfactant concentration, the equilibrium configuration crosses over from the disperse phase to the bicontinuous one. The crossover concentration is estimated. The conformation of the surfactant has little effect on the equilibrium concentration of surfactants at the interface,while it affects the equilibrium configuration after phase separation.

  12. Method development and validation for optimised separation of salicylic, acetyl salicylic and ascorbic acid in pharmaceutical formulations by hydrophilic interaction chromatography and response surface methodology. (United States)

    Hatambeygi, Nader; Abedi, Ghazaleh; Talebi, Mohammad


    This paper introduces a design of experiments (DOE) approach for method optimisation in hydrophilic interaction chromatography (HILIC). An optimisation strategy for the separation of acetylsalicylic acid, its major impurity salicylic acid and ascorbic acid in pharmaceutical formulations by HILIC is presented, with the aid of response surface methodology (RSM) and Derringer's desirability function. A Box-Behnken experimental design was used to build the mathematical models and then to choose the significant parameters for the optimisation by simultaneously taking both resolution and retention time as the responses. The refined model had a satisfactory coefficient (R²>0.92, n=27). The four independent variables studied simultaneously were: acetonitrile content of the mobile phase, pH and concentration of buffer and column temperature each at three levels. Of these, the concentration of buffer and its cross-product with pH had a significant, positive influence on all studied responses. For the test compounds, the best separation conditions were: acetonitrile/22 mM ammonium acetate, pH 4.4 (82:18, v/v) as the mobile phase and column temperature of 28°C. The methodology also captured the interaction between variables which enabled exploration of the retention mechanism involved. It would be inferred that the retention is governed by a compromise between hydrophilic partitioning and ionic interaction. The optimised method was further validated according to the ICH guidelines with respect to linearity and range, precision, accuracy, specificity and sensitivity. The robustness of the method was also determined and confirmed by overlying counter plots of responses which were derived from the experimental design utilised for method optimisation.

  13. Phase Diagram and Phase Separation of a Trapped Interacting Bose-Fermi Gas Mixture

    Institute of Scientific and Technical Information of China (English)

    MA Yong-Li


    @@ In six different regimes for a spatial phase diagram of a trapped interacting Bose-Fermi gas mixture at low temperatures, we present the conditions for the spatial demixing and separation of bosons and fermions. Starting from a semiclassically thermodynamic model for the local density functional of thermal bosons and fermions,the explicit analytical expressions for the fugacities of bosons and fermions are derived in different regimes by means of a first-order perturbation method in a local-density approximation. The critical values of the fermionboson interaction strength as a function of the fractional composition of fermions have a general feature: increase,extreme and decrease with increasing the fermionic composition slightly above Bose-Einstein critical temperature.

  14. [Separation mechanism of chiral stationary phase based on quinine and crown ether for the direct stereoselective separation of amino acids]. (United States)

    Wu, Haixia; Wang, Dongqiang; Zhao, Jianchao; Ke, Yanxiong; Liang, Xinmiao


    A novel chiral stationary phase combining quinine and crown ether (QN-CR CSP) was developed to separate amino acid enantiomers. This CSP showed good enantioselectivity for some amino acids. Since the synergistic effect of ion exchange and complexation in chiral recognition of amino acids, a new adsorption isotherm was built. Using the method of frontal analysis by characteristic point (FACP), the adsorption isotherms of tryptophan (Trp) under different mobile phase conditions were determined and fitted the proposed adsorption isotherm model well. With the increase of the competition between metal cationic and amino to crown ether, the equilibrium constant of complexing adsorption was found increased. The chiral separation ability was decreased. The adsorption isotherm improved the understanding of the retention behavior of amino acids on QN-CR CSP, which was also benefit to optimize the structure of the stationary phase.

  15. Rapid separation of desloratadine and related compounds in solid pharmaceutical formulation using gradient ion-pair chromatography. (United States)

    Zheng, Jinjian; Rustum, Abu M


    We reported the development of an ion-pair chromatographic method to separate desloratadine and all known related compounds in Clarinex Tablets, which use desloratadine as active pharmaceutical ingredient (API). For the first time, baseline separation for desloratadine and all known related compounds was achieved by utilizing a YMC-Pack Pro C(18) column (150 mm x 4.6 mm I.D., 3 microm particle size, 120A pore size) and a gradient elution method. The mobile phase A contains 3 mM sodium dodecylsulfate (SDS), 15 mM sodium citrate buffer at pH 6.2, and 40 mM sodium sulfate, while the mobile phase B is acetonitrile. Chromsword, an artificial intelligence method development tool, was used to optimize several key chromatographic parameters simultaneously including buffer pH/solvent strength, and temperature/gradient profile. The resolution of desloratadine and desloratadine 3,4-dehydropiperidine derivative, one of the critical pairs was improved by adding 40 mM sodium sulfate. Ultraviolet detection at 267 nm was used to achieve the detection for desloratadine and all compounds. This method has been successfully validated according to ICH guidelines in terms of linearity, accuracy, quantitation limit/detection limit, precision, specificity and robustness. It could be used as a stability indicating method for desloratadine drug substances or drug products that use desloratadine as active pharmaceutical ingredient.

  16. Thermodynamic Model Formulations for Inhomogeneous Solids with Application to Non-isothermal Phase Field Modelling (United States)

    Gladkov, Svyatoslav; Kochmann, Julian; Reese, Stefanie; Hütter, Markus; Svendsen, Bob


    The purpose of the current work is the comparison of thermodynamic model formulations for chemically and structurally inhomogeneous solids at finite deformation based on "standard" non-equilibrium thermodynamics [SNET: e. g. S. de Groot and P. Mazur, Non-equilibrium Thermodynamics, North Holland, 1962] and the general equation for non-equilibrium reversible-irreversible coupling (GENERIC) [H. C. Öttinger, Beyond Equilibrium Thermodynamics, Wiley Interscience, 2005]. In the process, non-isothermal generalizations of standard isothermal conservative [e. g. J. W. Cahn and J. E. Hilliard, Free energy of a non-uniform system. I. Interfacial energy. J. Chem. Phys. 28 (1958), 258-267] and non-conservative [e. g. S. M. Allen and J. W. Cahn, A macroscopic theory for antiphase boundary motion and its application to antiphase domain coarsening. Acta Metall. 27 (1979), 1085-1095; A. G. Khachaturyan, Theory of Structural Transformations in Solids, Wiley, New York, 1983] diffuse interface or "phase-field" models [e. g. P. C. Hohenberg and B. I. Halperin, Theory of dynamic critical phenomena, Rev. Modern Phys. 49 (1977), 435-479; N. Provatas and K. Elder, Phase Field Methods in Material Science and Engineering, Wiley-VCH, 2010.] for solids are obtained. The current treatment is consistent with, and includes, previous works [e. g. O. Penrose and P. C. Fife, Thermodynamically consistent models of phase-field type for the kinetics of phase transitions, Phys. D 43 (1990), 44-62; O. Penrose and P. C. Fife, On the relation between the standard phase-field model and a "thermodynamically consistent" phase-field model. Phys. D 69 (1993), 107-113] on non-isothermal systems as a special case. In the context of no-flux boundary conditions, the SNET- and GENERIC-based approaches are shown to be completely consistent with each other and result in equivalent temperature evolution relations.

  17. Controllable Phase Separation by Boc-Modified Lipophilic Acid as a Multifunctional Extractant (United States)

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


    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.

  18. Flow-induced phase separation in polymer solutions

    NARCIS (Netherlands)

    Moel, K. de; Flikkema, E.; Szleifer, I.; Brinke, G. ten


    A correct description of phase behaviour in polymer solutions requires a coupling between configurational statistics and thermodynamics. The effect of flow-induced chain deformation on the polymer-solvent interaction energy depends on the concentration and on the polymer architecture. It will be dem

  19. Simulations of Noise in Phase-Separated Transition-Edge Sensors for SuperCDMS

    CERN Document Server

    Anderson, A J; Pyle, M; Figueroa-Feliciano, E; McCarthy, K; Doughty, T; Cherry, M; Young, B


    We briefly review a simple model of superconducting-normal phase-separation in transition-edge sensors in the SuperCDMS experiment. After discussing some design considerations relevant to the TES in the detectors, we study noise sources in both the phase-separated and phase-uniform cases. Such simulations are valuable for optimizing the critical temperature and TES length of future SuperCDMS detectors.

  20. Loss-induced phase separation and pairing for three-species atomic lattice fermions

    Energy Technology Data Exchange (ETDEWEB)

    Privitera, A. [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, 60438 Frankfurt am Main (Germany); Dipartimento di Fisica, Universita di Roma La Sapienza, I-00185 Roma (Italy); Democritos National Simulation Center, Consiglio Nazionale delle Ricerche, Istituto Officina dei Materiali (CNR-IOM) and International School for Advanced Studies (SISSA), I-34136 Trieste (Italy); Titvinidze, I.; Hofstetter, W. [Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, 60438 Frankfurt am Main (Germany); Chang, S.-Y. [Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, and Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria); Department of Physics, Ohio State University, Columbus, OH 43210 (United States); Diehl, S.; Daley, A. J. [Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, and Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck (Austria)


    We study the physics of a three-component Fermi gas in an optical lattice, in the presence of a three-body constraint arising due to strong three-body loss. Using analytical and numerical techniques, we show that an atomic color superfluid phase is formed in this system and undergoes phase separation between unpaired fermions and superfluid pairs. This phase separation survives well above the critical temperature, giving a clear experimental signature of the three-body constraint.

  1. Direct NMR Monitoring of Phase Separation Behavior of Highly Supersaturated Nifedipine Solution Stabilized with Hypromellose Derivatives. (United States)

    Ueda, Keisuke; Higashi, Kenjirou; Moribe, Kunikazu


    We investigated the phase separation behavior and maintenance mechanism of the supersaturated state of poorly water-soluble nifedipine (NIF) in hypromellose (HPMC) derivative solutions. Highly supersaturated NIF formed NIF-rich nanodroplets through phase separation from aqueous solution containing HPMC derivative. Dissolvable NIF concentration in the bulk water phase was limited by the phase separation of NIF from the aqueous solution. HPMC derivatives stabilized the NIF-rich nanodroplets and maintained the NIF supersaturation with phase-separated NIF for several hours. The size of the NIF-rich phase was different depending on the HPMC derivatives dissolved in aqueous solution, although the droplet size had no correlation with the time for which NIF supersaturation was maintained without NIF crystallization. HPMC acetate and HPMC acetate succinate (HPMC-AS) effectively maintained the NIF supersaturation containing phase-separated NIF compared with HPMC. Furthermore, HPMC-AS stabilized NIF supersaturation more effectively in acidic conditions. Solution (1)H NMR measurements of NIF-supersaturated solution revealed that HPMC derivatives distributed into the NIF-rich phase during the phase separation of NIF from the aqueous solution. The hydrophobicity of HPMC derivative strongly affected its distribution into the NIF-rich phase. Moreover, the distribution of HPMC-AS into the NIF-rich phase was promoted at lower pH due to the lower aqueous solubility of HPMC-AS. The distribution of a large amount of HPMC derivatives into NIF-rich phase induced the strong inhibition of NIF crystallization from the NIF-rich phase. Polymer distribution into the drug-rich phase directly monitored by solution NMR technique can be a useful index for the stabilization efficiency of drug-supersaturated solution containing a drug-rich phase.

  2. Effect of phase separation structure on cementitious reactivity of blast furnace slag

    Institute of Scientific and Technical Information of China (English)

    LI Yu; SUN HengHu; LIU XiaoMing; CUI ZengDi


    Blast furnace slag samples with phase separation structure were prepared by re-melting and then water quenching process. By use of XRD, DTA and SEM technologies in combination with mechanical prop-erty experiment, the structure characteristics of samples were determined and their effects on cemen-titious reactivity were investigated. The results show that the samples with phase separation have better cementitious reactivity than sample with homogenous glass and sample with crystalline phases, which mainly contributes to its grass structure with coexistence of Ca-O rich phase and Si-O rich phase. Moreover, the amorphous samples possess hydrability which is affected by their formation process, since phase separation extends the range of possible Ca-rich crystalline phases.

  3. Effect of phase separation structure on cementitious reactivity of blast furnace slag

    Institute of Scientific and Technical Information of China (English)


    Blast furnace slag samples with phase separation structure were prepared by re-melting and then water quenching process. By use of XRD,DTA and SEM technologies in combination with mechanical property experiment,the structure characteristics of samples were determined and their effects on cementitious reactivity were investigated. The results show that the samples with phase separation have better cementitious reactivity than sample with homogenous glass and sample with crystalline phases,which mainly contributes to its glass structure with coexistence of Ca-O rich phase and Si-O rich phase. Moreover,the amorphous samples possess hydrability which is affected by their formation process,since phase separation extends the range of possible Ca-rich crystalline phases.

  4. Dielectric matrix formulation of correlation energies in the Random Phase Approximation (RPA): inclusion of exchange effects

    CERN Document Server

    Mussard, Bastien; Jansen, Georg; Angyan, Janos


    Starting from the general expression for the ground state correlation energy in the adiabatic connection fluctuation dissipation theorem (ACFDT) framework, it is shown that the dielectric matrix formulation, which is usually applied to calculate the direct random phase approximation (dRPA) correlation energy, can be used for alternative RPA expressions including exchange effects. Within this famework, the ACFDT analog of the second order screened exchange (SOSEX) approximation leads to a logarithmic formula for the correlation energy similar to the direct RPA expression. Alternatively, the contribution of the exchange can be included in the kernel used to evaluate the response functions. In this case the use of an approximate kernel is crucial to simplify the formalism and to obtain a correlation energy in logarithmic form. Technical details of the implementation of these methods are discussed and it is shown that one can take advantage of density fitting or Cholesky decomposition techniques to improve the co...

  5. A thermodynamical formulation for chemically active multi-phase turbulent flows

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadi, G.; Cao, J.


    A generalized thermodynamics for chemically active multiphase solid-fluid mixtures in turbulent state of motion is formulated. The global equations of balance for each phase are ensemble averaged and the local conservation laws for the mean motions are derived. The averaged and the local conservation laws for the mean motions are derived. The averaged form of the Clausius-Duhem inequality is used and the thermodynamics of the chemically active mixtures in turbulent motion is studied. Particular attention is given to the species concentration and chemical reaction effects, in addition to transport and interaction of the phasic fluctuation energies. Based on the averaged entropy inequality, constitutive equations for the stresses, energy, heat and mass fluxes of various species are developed. The explicit governing equations of motion are derived and discussed.

  6. Lifshitz-Slyozov kinetics of a nonconserved system that separates into phases of different density

    DEFF Research Database (Denmark)

    Mouritsen, Ole G.; Shah, Peter Jivan; Andersen, Jørgen Vitting


    Computer-simulation techniques are applied to analyze the late-stage ordering kinetics of a two-dimensional annealed dilute Ising model quenched into regions of its phase diagram that involve phase separation of phases with different densities. The order parameter of the model is a nonconserved q...

  7. In situ imaging and height reconstruction of phase separation processes in polymer blends during spin coating. (United States)

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


    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.

  8. Monte Carlo simulations of the phase separation of a copolymer blend in a thin film

    KAUST Repository

    Wang, Zhexiao


    Monte Carlo simulations were carried out to study the phase separation of a copolymer blend comprising an alternating copolymer and/or block copolymer in a thin film, and a phase diagram was constructed with a series of composed recipes. The effects of composition and segregation strength on phase separation were discussed in detail. The chain conformation of the block copolymer and alternating copolymer were investigated with changes of the segregation strength. Our simulations revealed that the segment distribution along the copolymer chain and the segregation strength between coarse-grained beads are two important parameters controlling phase separation and chain conformation in thin films of a copolymer blend. A well-controlled phase separation in the copolymer blend can be used to fabricate novel nanostructures.

  9. Soft nanostructuring of YBCO Josephson junctions by phase separation. (United States)

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


    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.

  10. Solute redistribution during phase separation of ternary Fe-Cu-Si alloy (United States)

    Luo, S. B.; Wang, W. L.; Xia, Z. C.; Wu, Y. H.; Wei, B.


    Ternary Fe48Cu48Si4 immiscible alloy was rapidly solidified under the containerless microgravity condition inside a drop tube. Liquid phase separation took place in the alloy melt and led to the formation of various segregated structures. The core-shell structure consisting of Fe-rich and Cu-rich zones and the homogenously dispersed structure were the major structural morphologies. Phase field simulation results revealed that the two-layer core-shell was the final structure of liquid phase separation. The solute redistribution of liquid Fe48Cu48Si4 alloy experienced the macroscopic solute distribution induced by liquid phase separation, the secondary phase separation within the separated liquid phases and the solute trapping during rapid solidification. Energy dispersive spectroscopy analysis showed that the solute Si was enriched in the Fe-rich zone whereas depleted in the Cu-rich zone. In addition, both αFe and (Cu) phases in the Fe-rich zone exhibited a conspicuous solute trapping effect. As compared with (Cu) phase, αFe phase had a stronger affinity with solute Si.

  11. Mixed-mode reversed phase/positively charged repulsion chromatography for intact protein separation. (United States)

    Ding, Ling; Guo, Zhimou; Hu, Zhuo; Liang, Xinmiao


    A mixed-mode reversed phase/positively charged repulsion stationary phase C8PN composed of octyl and amino group has been developed for separation of intact protein. Before the separation of proteins, a set of probe compounds were employed to evaluate the chromatographic properties of C8PN, demonstrating typical reversed phase/positively charged repulsion interaction on this stationary phase as estimated. Then the new C8PN stationary phase was used to separate a standard protein mixture on the reversed phase mode. Compared with a commercial C4 stationary phase, it showed different selectivity for some proteins. In order to better understand the properties of C8PN, the effect of acetonitrile content was investigated based on retention equation. Higher values of the equation parameters on C8PN demonstrated that the protein retentions were more sensitive to the change of acetonitrile content. Besides, the influences of buffer salt additives on the protein retentions were also studied. The retention factors of the proteins got larger with the increase of buffer salt concentration, which confirmed the positively charged repulsion interaction on the column. Finally, the C8PN was further applied to separate oxidized- and reduced- forms of Recombinant Human Growth Hormone. Our study indicated the advantages and application potential of mixed-mode reversed phase/positively charged repulsion stationary phase for intact protein separation. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Microscopic origin of the magnetoelectronic phase separation in Sr-doped LaCoO3 (United States)

    Németh, Zoltán; Szabó, András; Knížek, Karel; Sikora, Marcin; Chernikov, Roman; Sas, Norbert; Bogdán, Csilla; Nagy, Dénes Lajos; Vankó, György


    The nanoscopic magnetoelectronic phase separation in doped La1-xSrxCoO3 perovskites was studied with local probes. The phase separation is directly observed by Mössbauer spectroscopy in the studied doping range of 0.05 ≤ x ≤ 0.25 both at room temperature and in the low-temperature magnetic phase. Extended with current synchrotron-based x-ray spectroscopies, these data help to characterize the volume as well as the local electric and magnetic properties of the distinct phases. A simple model based on a random distribution of the doping Sr ions describes well both the evolution of the separated phases and the variation of the Co spin state. The experiments suggest that Sr doping initiates small droplets and a high degree of doping-driven cobalt spin-state transition, while the Sr-free second phase vanishes rapidly with increasing Sr content.

  13. Reaction-induced phase separation in rubber-modified epoxy resin

    Institute of Scientific and Technical Information of China (English)

    张剑文; 张红东; 严栋; 周红卫; 杨玉良


    The phase separation mechanism,and structure development during curing of epoxy with a novel liquid rubber-ZR were investigated by time-resolved light scattering,optical microscope and differential scanning calonmetry (DSC) The mixture loaded with curing agent was a single-phase system in the early stage of curing.When the cure reaction proceeded,phase separation took place via the spinodal decomposition induced by polymerization of epoxy resin.This was supported by the characteristic change of light scattering profile with curing time.Cure reaction plays an important role in the progress of phase separation.The bigger the cure reaction rate is,the longer periodic distance will be.The overall two-phase structure was basically locked in when the conversion approached 80% estimated by DSC,and finally the co-continuous two-phase structure was successfully obtained.

  14. Phase behavior and molecular dynamics simulation studies of new aqueous two-phase separation systems induced by HEPES buffer. (United States)

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


    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.

  15. Amide-induced phase separation of hexafluoroisopropanol-water mixtures depending on the hydrophobicity of amides. (United States)

    Takamuku, Toshiyuki; Wada, Hiroshi; Kawatoko, Chiemi; Shimomura, Takuya; Kanzaki, Ryo; Takeuchi, Munetaka


    Amide-induced phase separation of hexafluoro-2-propanol (HFIP)-water mixtures has been investigated to elucidate solvation properties of the mixtures by means of small-angle neutron scattering (SANS), (1)H and (13)C NMR, and molecular dynamics (MD) simulation. The amides included N-methylformamide (NMF), N-methylacetamide (NMA), and N-methylpropionamide (NMP). The phase diagrams of amide-HFIP-water ternary systems at 298 K showed that phase separation occurs in a closed-loop area of compositions as well as an N,N-dimethylformamide (DMF) system previously reported. The phase separation area becomes wider as the hydrophobicity of amides increases in the order of NMF amides due to the hydrophobic interaction gives rise to phase separation of the mixtures. In contrast, the disruption of HFIP clusters causes the recovery of the homogeneity of the ternary systems. The present results showed that HFIP clusters are evolved with increasing amide content to the lower phase separation concentration in the same mechanism among the four amide systems. However, the disruption of HFIP clusters in the NMP and DMF systems with further increasing amide content to the upper phase separation concentration occurs in a different way from those in the NMF and NMA systems.

  16. Applied catastrophic phase inversion: a continuous non-centrifugal phase separation step in biphasic whole-cell biocatalysis. (United States)

    Glonke, Sebastian; Sadowski, Gabriele; Brandenbusch, Christoph


    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.

  17. Separation of electrostatic and magnetic phase shifts using a modified transport-of-intensity equation

    Energy Technology Data Exchange (ETDEWEB)

    Humphrey, E. [Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Phatak, C.; Petford-Long, A.K. [Argonne National Laboratory, Argonne, IL 60439 (United States); De Graef, M. [Carnegie Mellon University, Pittsburgh, PA 15213 (United States)


    We introduce a new approach for the separation of the electrostatic and magnetic components of the electron wave phase shift, based on the transport-of-intensity equation (TIE) formalism. We derive two separate TIE-like equations, one for each of the phase shift components. We use experimental results on FeCoB and Permalloy patterned islands to illustrate how the magnetic and electrostatic longitudinal derivatives can be computed. The main advantage of this new approach is the fact that the differences in the power spectra of the two phase components (electrostatic phase shifts often have significant power in the higher frequencies) can be accommodated by the selection of two different Tikhonov regularization parameters for the two phase reconstructions. The extra computational demands of the method are more than compensated by the improved phase reconstruction results. - Highlights: • We provide a new way to separate electrostatic and magnetic phase shifts in Lorentz microscopy. • We derive two new transport-of-intensity style equations, one for electrostatic phase shifts and the other for magnetic phase shifts. • We provide a new way to determine the longitudinal intensity derivative that automatically includes time reversal symmetry. • This approach allows for the Tikhonov regularization parameter to be selected for each phase shift separately. • We provide two example application on Permalloy and CoFeB patterned islands.

  18. Spectro-microscopic Characterization of Physical Properties and Phase Separations in Individual Atmospheric Particles (United States)

    OBrien, R. E.; Wang, B.; Neu, A.; Kelly, S. T.; Lundt, N.; Epstein, S. A.; MacMillan, A.; You, Y.; Laskin, A.; Nizkorodov, S.; Bertram, A. K.; Moffet, R.; Gilles, M.


    The phase state and liquid-liquid phase separations of ambient and laboratory generated aerosol particles were investigated using (1) scanning transmission x-ray microscopy/near-edge x-ray absorption fine structure spectroscopy (STXM/NEXAFS) coupled to a relative humidity (RH) controlled in-situ chamber and (2) environmental scanning electron microscopy (ESEM). The phase states of the particles were determined from measurements of their size and optical density. A comparison is made between the observed phase states of ambient samples and of laboratory generated aerosols to determine how well laboratory samples represent the phase of ambient samples. In addition, liquid-liquid phase separations in laboratory generated particles were investigated. Preliminary results showing that liquid-liquid phase separations occur at RH's between the deliquescence and efflorescence points and that the organic phase surrounds the inorganic phase will be presented. The STXM/NEXAFS technique provides insight into the degree of mixing at the deliquescence point and the degree of phase separation for particles of atmospherically relevant sizes.

  19. Fast separation of hen egg white protein with a phosphorylcholine type zwitterionic ion chromatography stationary phase

    Institute of Scientific and Technical Information of China (English)

    Qian Qu; Xiu Juan Yu; Xi Wu; Fei Shi; Li Li Wang


    In this work,a kind of preparation method of zwitterionic ion chromatography (ZIC) stationary phase modified with phosphorylcholine (PC) was obtained by hydrolyzing after bonding phosphorylcholine dichloride to diol-silica to better explore the characteristics of the PC groups as ZIC stationary phase ligand in simultaneous separation of acidic proteins and basic proteins.The results showed that two kinds of acidic proteins and three kinds of basic proteins can be separated completely,meanwhile,hen egg white was separated and purified and three kinds of egg white components ovalbumin,G2 ovoglobulin and ovotransfemin proteins were separated completely by one single step on PC-ZIC column,the purity of all proteins reached above 95%.PC-ZIC stationary phase was successfully improved with better separation capacity and selectivity than previously reported in this paper.


    Institute of Scientific and Technical Information of China (English)


    Microporous ethylene-vinyl alcohol copolymer (EVOH) flat membranes and hollow-fiber membranes with 38 mol% ethylene content were prepared via thermally induced phase separation (TIPS) using the mixture of 1,4-butanediol and poly(ethylene glycol)(PEG400) as diluents. Effects of the ratio of 1,4-butanediol to PEG400 on the phase diagrams, phase separation mechanism and membrane morphology were studied by small angle light scattering (SALS) measurements, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). It was found that by varying the composition of the binary solvent, the phase diagrams and membrane morphology can be controlled successfully. Moreover, the phase diagrams showed that broader regions of Liquid-Liquid (L-L) phase separation were obtained, as well as closer distances between L-L phase separation lines and Solid-Liquid (S-L) phase separation lines. Interconnected structures observed both in the flat membrane and hollow fiber membrane consist with the above results.

  1. On the implications of aerosol liquid water and phase separation for organic aerosol mass (United States)

    U.S. Environmental Protection Agency — This dataset contains data presented in the figures of the paper "On the implications of aerosol liquid water and phase separation for organic aerosol mass"...

  2. An asymmetric tubular ceramic-carbonate dual phase membrane for high temperature CO2 separation. (United States)

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


    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.

  3. Development of the Two Phase Flow Separator Experiment for a Reduced Gravity Aircraft Flight (United States)

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


    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.

  4. Sterol structure determines the separation of phases and the curvature of the liquid-ordered phase in model membranes. (United States)

    Bacia, Kirsten; Schwille, Petra; Kurzchalia, Teymuras


    The existence of lipid rafts in biological membranes in vivo is still debated. In contrast, the formation of domains in model systems has been well documented. In giant unilamellar vesicles (GUVs) prepared from ternary mixtures of dioleoyl-phosphatidylcholine/sphingomyelin/cholesterol, a clear separation of liquid-disordered and sphingomyelin-enriched, liquid-ordered phases could be observed. This phase separation can lead to the fission of the liquid-ordered phase from the vesicle. Here we show that in cholesterol-containing GUVs, the phase separation can involve dynamic redistribution of lipids from one phase into another as a result of a cross-linking perturbation. We found that the molecular structure of a sterol used for the preparation of GUVs determines (i) its ability to induce phase separation and (ii) the curvature (positive or negative) of the formed liquid-ordered phase. As a consequence, the latter can pinch off to the outside or inside of the vesicle. Remarkably, some mixtures of sterols induce liquid-ordered domains exhibiting both positive and negative curvature, which can lead to a new type of budding behavior in GUVs. Our findings could have implications for the role of sterols in various cell-biological processes such as budding of secretory vesicles, endocytosis, or formation of multivesicular bodies.

  5. Silica-based polypeptide-monolithic stationary phase for hydrophilic chromatography and chiral separation. (United States)

    Zhao, Licong; Yang, Limin; Wang, Qiuquan


    Glutathione (GSH)-, somatostatin acetate (ST)- and ovomucoid (OV)-functionalized silica-monolithic stationary phases were designed and synthesized for HILIC and chiral separation using capillary electrochromatography (CEC). GSH, ST and OV were covalently incorporated into the silica skeleton via the epoxy ring-opening reaction between their amino groups and the glycidyl moiety in γ-glycidoxypropyltrimethoxysilane (GPTMS) together with polycondensation and copolymerization of tetramethyloxysilane and GPTMS. Not only could the direction and electroosmotic flow magnitude on the prepared GSH-, ST- and OV-silica hybrid monolithic stationary phases be controlled by the pH of the mobile phase, but also a typical HILIC behavior was observed so that the nucleotides and HPLC peptide standard mixture could be baseline separated using an aqueous mobile phase without any acetonitrile during CEC. Moreover, the prepared monolithic columns had a chiral separation ability to separate dl-amino acids. The OV-silica hybrid monolithic column was most effective in chiral separation and could separate dl-glutamic acid (Glu) (the resolution R=1.07), dl-tyrosine (Tyr) (1.57) and dl-histidine (His) (1.06). Importantly, the chiral separation ability of the GSH-silica hybrid monolithic column could be remarkably enhanced when using gold nanoparticles (AuNPs) to fabricate an AuNP-mediated GSH-AuNP-GSH-silica hybrid monolithic column. The R of dl-Glu, dl-Tyr and dl-His reached 1.19, 1.60 and 2.03. This monolithic column was thus applied to separate drug enantiomers, and quantitative separation of all four R/S drug enantiomers were achieved with R ranging from 4.36 to 5.64. These peptide- and protein-silica monolithic stationary phases with typical HILIC separation behavior and chiral separation ability implied their promise for the analysis of not only the future metabolic studies, but also drug enantiomers recognition.

  6. Near-critical fluctuations and cytoskeleton-assisted phase separation lead to subdiffusion in cell membranes

    CERN Document Server

    Ehrig, Jens; Schwille, Petra


    We address the relationship between membrane microheterogeneity and anomalous subdiffusion in cell membranes by carrying out Monte Carlo simulations of two-component lipid membranes. We find that near-critical fluctuations in the membrane lead to transient subdiffusion, while membrane-cytoskeleton interaction strongly affects phase separation, enhances subdiffusion, and eventually leads to hop diffusion of lipids. Thus, we present a minimum realistic model for membrane rafts showing the features of both microscopic phase separation and subdiffusion.

  7. A Novel Method for Modification of SMPU by Micro-phase Separation Promoters

    Institute of Scientific and Technical Information of China (English)


    A novel method of controlling the shape memory properties of shape memory polyurethane (SMPU) by addition of micro-phase separation promoters including 1-octadecanol (ODO) and liquid paraffin (LP) is reported. The results indicate that the strain recovery temperature and the strain modulus rate (Eg/Er) were increased significantly with addition of small amount of micro-phase separation promoters. Thus it can increase the shape memory fixity rate and other shape memory behaviors of SMPU.

  8. Phase Separation of Binary Charged Particle Systems with Small Size Disparities using a Dusty Plasma. (United States)

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


    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.

  9. Phase equilibrium measurements and modelling for separation process design

    Energy Technology Data Exchange (ETDEWEB)

    Dell' Era, C.


    the thermodynamic representation of the equilibrium between phases. For this purpose an extensive experimental work was performed, comprising of vapour-liquid, gas-liquid and solid-liquid equilibrium measurements. Vapour liquid equilibrium of binary mixtures of butane + alcohols was measured with a static total pressure apparatus due to the importance of hydrocarbon and alcohol mixtures in the production of biofuels. The same equipment was used to measure binary systems of diethyl sulphide + C4 - hydrocarbons of importance in refinery applications. The activity coefficients of these systems were modelled with activity coefficients models. The absorption of carbon dioxide in alkanolamine solutions is the leading technology for the removal of carbon dioxide during refining of gas and oil. In recent years, this technology has gained importance also for carbon capture from large point sources. The scarcity of experimental data for some alkanolamine systems affected the accuracy of thermodynamic models. Several experimental techniques were developed to supply new experimental data for aqueous solutions of diisopropanolamine (DIPA) and methyldiethanolamine (MDEA). The solubility of carbon dioxide in solutions of these amines was measured with a static total pressure apparatus for gas solubility, and with a bubbling apparatus. The density of carbonated aqueous DIPA was also measured and modelled. The vapour-liquid equilibrium of water + DIPA and water + MDEA was measured with a static total pressure apparatus. The solid-liquid equilibrium of the same systems was measured with a visual method and a Differential Scanning Calorimeter. The activity coefficients of aqueous DIPA and MDEA solutions were modelled using NRTL, thus providing the first model of this sort for DIPA. A new model of the Henry's law constant of carbon dioxide in binary and ternary aqueous solutions of alkanolamines was developed at temperatures up to 393 K. (orig.)

  10. Orbiter/carrier separation for the ALT free flight no. 1 reference trajectories. Mission planning, mission analysis and software formulation (United States)

    Glenn, G. M.


    Details of the generation of the separation trajectories are discussed. The analysis culminated in definition of separation trajectories between physical separation and orbiter/carrier vortex clearance. Specifications, assumptions and analytical approach used to generate the separation trajectories are presented. Results of the analytical approach are evaluated. Conclusions and recommendations are summarized. Supporting references are listed.

  11. Phase separation time/temperature dependence of thermoplastics-modified thermosetting systems

    Institute of Scientific and Technical Information of China (English)

    Xiujuan ZHANG; Xiaosu YI; Yuanze XU


    The cure-induced phase separation processes of various thermoplastics(TP)-modified thermosetting systems which show upper critical solution temperature (UCST) or lower critical solution temperature (LCST) were studied with emphasis on the temperature depend-ency of the phase separation time and its potential application in the cure time-temperature processing win-dow.We found that the phase separation time/temper-ature relationship follows the simple Arrhenius equation.The cure-induced phase separation activation energy Ea(ps) generated from the linear fitting of the Arrhenius equation is irrelevant to the detection means of phase separation time.We also found that Ea(ps) is insensitive to TP content,TP molecular weight and curing rate,but it changes with the cure reaction kinetics and the chemical environment of the systems.With the established phase separation time-temperature dependence relation,we can easily establish the whole cure time-temperature transformation (TTT) diagram with morphology information which is a useful map for the TP/TS compo-sites processing industry.

  12. Suppression of turbulent energy cascade due to phase separation in homogenous binary mixture fluid (United States)

    Takagi, Youhei; Okamoto, Sachiya


    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.

  13. Solvent-mediated pathways to gelation and phase separation in suspensions of grafted nanoparticles

    KAUST Repository

    Anyfantakis, Manos


    We explore the role of the solvent medium on the interplay between gelation and phase separation in suspensions of organosilicate planar hybrids grafted with hydrocarbon chains. We establish their phase diagram by means of dynamic light scattering, rheology and visual observations, and different routes to gelation, depending on the solvent used. In agreement with earlier works, the solvent quality for the grafted chains at a given temperature controls the balance between attractions and repulsions, and hence the phase diagram of the nanoparticles and their tendency to gel. Here we show how to tune the suspension state and hence its rheology. For decane, a good solvent for the hydrocarbon chains, gelation occurs at rather low volume fractions in the presence of phase separation. This is due to the interdigitation of solvent molecules with the grafted chains, resulting in their crystalline packing that promotes the attraction between particles. For toluene, a solvent of reduced quality for the hydrocarbon chains, no interdigitation takes place, and hence gelation is triggered by clustering at higher volume fractions before phase separation. Our results support the generic picture of complex kinetic arrest/phase separation interplay in soft matter, where phase separation can proceed, be interrupted or be completely inhibited. A number of interesting possibilities for tailoring the rheology of grafted colloidal systems emerge. © 2009 The Royal Society of Chemistry.

  14. Phase-uncertainty quality map for two-point Dixon fat-water separation (United States)

    Schmidt, Maria A.


    This work investigates and compares two different phase-correction algorithms for Dixon fat-water separation and two different quality maps (QM) for region-growing: the original QM, based on phase gradients, and a QM based on phase uncertainty, proposed in this article. A spoiled dual-gradient-echo sequence was employed at 1.5 T to acquire in-phase and out-of-phase images of joints, parotid glands, abdomen and test objects. All 97 datasets were processed eight times each: with two different phase correction algorithms (original and hierarchical phase correction), with two different QM, and with/without removing linear component of the phase drifts associated with dual-echo acquisitions and bipolar readout gradient waveforms. The linear component of the phase drift along the readout direction was found to reach 4.1° pixel-1, depending on the geometric parameters. Pre-processing to remove linear phase shifts has little impact on outcome. The hierarchic phase-correction algorithm outperformed the original phase-correction algorithm in all applications. The proposed phase-uncertainty QM provides a small performance improvement in clinical images, but can be vulnerable to flow-related phase shifts in bright vessels. Overall the most successful phase-correction technique employed phase-uncertainty QMs and hierarchic algorithms, with pre-processing to correct the linear phase drift associated with dual-echo acquisitions and bipolar readout gradient waveform.

  15. Effect of confinement and kinetics on the morphology of phase separating gelatin-maltodextrin droplets. (United States)

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


    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.

  16. Gas-liquid two-phase flows in double inlet cyclones for natural gas separation

    DEFF Research Database (Denmark)

    Yang, Yan; Wang, Shuli; Wen, Chuang


    The gas-liquid two-phase flow within a double inlet cyclone for natural gasseparation was numerically simulated using the discrete phase model. The numericalapproach was validated with the experimental data, and the comparison resultsagreed well with each other. The simulation results showed......-outlet. The swirling flow was concentric dueto the design of the double inlet for the cyclonic separator, which greatly improvedthe separating efficiency. The separating efficiency was greater than 90% with theparticle diameter of more than 100 μm....

  17. The Two-Phase Flow Separator Experiment Breadboard Model: Reduced Gravity Aircraft Results (United States)

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


    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.

  18. Single channel source separation of radar fuze mixed signal based on phase difference analysis

    Institute of Scientific and Technical Information of China (English)

    Hang ZHU; Shu-ning ZHANG; Hui-chang ZHAO


    A new method based on phase difference analysis is proposed for the single-channel mixed signal separation of single-channel radar fuze. This method is used to estimate the mixing coefficients of de-noised signals through the cumulants of mixed signals, solve the candidate data set by the mixing coefficients and signal analytical form, and resolve the problem of vector ambiguity by analyzing the phase differences. The signal separation is realized by exchanging data of the solutions. The waveform similarity coefficients are calculated, and the timeefrequency dis-tributions of separated signals are analyzed. The results show that the proposed method is effective.

  19. Preparation and Characterization of Silicone Liquid Core/Polymer Shell Microcapsules via Internal Phase Separation

    DEFF Research Database (Denmark)

    Gonzalez, Lidia; Kostrzewska, Malgorzata; Ma, Baoguang


    Microcapsules with a silicone liquid core surrounded by a polymeric shell were synthesisedthrough the controlled phase separation. The dispersed silicone phase consisted of the shellpolymer PMMA, a good solvent for the PMMA (dichloromethane, DCM) and a poor solvent(methylhydrosiloxane dimethylsil...

  20. Phase field approach with anisotropic interface energy and interface stresses: Large strain formulation (United States)

    Levitas, Valery I.; Warren, James A.


    A thermodynamically consistent, large-strain, multi-phase field approach (with consequent interface stresses) is generalized for the case with anisotropic interface (gradient) energy (e.g. an energy density that depends both on the magnitude and direction of the gradients in the phase fields). Such a generalization, if done in the "usual" manner, yields a theory that can be shown to be manifestly unphysical. These theories consider the gradient energy as anisotropic in the deformed configuration, and, due to this supposition, several fundamental contradictions arise. First, the Cauchy stress tensor is non-symmetric and, consequently, violates the moment of momentum principle, in essence the Herring (thermodynamic) torque is imparting an unphysical angular momentum to the system. In addition, this non-symmetric stress implies a violation of the principle of material objectivity. These problems in the formulation can be resolved by insisting that the gradient energy is an isotropic function of the gradient of the order parameters in the deformed configuration, but depends on the direction of the gradient of the order parameters (is anisotropic) in the undeformed configuration. We find that for a propagating nonequilibrium interface, the structural part of the interfacial Cauchy stress is symmetric and reduces to a biaxial tension with the magnitude equal to the temperature- and orientation-dependent interface energy. Ginzburg-Landau equations for the evolution of the order parameters and temperature evolution equation, as well as the boundary conditions for the order parameters are derived. Small strain simplifications are presented. Remarkably, this anisotropy yields a first order correction in the Ginzburg-Landau equation for small strains, which has been neglected in prior works. The next strain-related term is third order. For concreteness, specific orientation dependencies of the gradient energy coefficients are examined, using published molecular dynamics

  1. Dielectric Matrix Formulation of Correlation Energies in the Random Phase Approximation: Inclusion of Exchange Effects. (United States)

    Mussard, Bastien; Rocca, Dario; Jansen, Georg; Ángyán, János G


    Starting from the general expression for the ground state correlation energy in the adiabatic-connection fluctuation-dissipation theorem (ACFDT) framework, it is shown that the dielectric matrix formulation, which is usually applied to calculate the direct random phase approximation (dRPA) correlation energy, can be used for alternative RPA expressions including exchange effects. Within this famework, the ACFDT analog of the second order screened exchange (SOSEX) approximation leads to a logarithmic formula for the correlation energy similar to the direct RPA expression. Alternatively, the contribution of the exchange can be included in the kernel used to evaluate the response functions. In this case, the use of an approximate kernel is crucial to simplify the formalism and to obtain a correlation energy in logarithmic form. Technical details of the implementation of these methods are discussed, and it is shown that one can take advantage of density fitting or Cholesky decomposition techniques to improve the computational efficiency; a discussion on the numerical quadrature made on the frequency variable is also provided. A series of test calculations on atomic correlation energies and molecular reaction energies shows that exchange effects are instrumental for improvement over direct RPA results.

  2. Separation of piracetam derivatives on polysaccharide-based chiral stationary phases. (United States)

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


    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. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Separation of xylenes on Y zeolites in the vapor phase. 3. Choice of the suitable desorbent

    Energy Technology Data Exchange (ETDEWEB)

    Storti,; Carra, S.; Morbidelli, M.; Santacesaria, E.


    The choice of the most efficient desorbent is a key factor in the optimum design of an adsorption separation process through displacement chromatography. In this work different compounds are tested about their application as desorbent in the vapor phase adsorption separation of xylenes on Y zeolites. Among these, isopropylbenzene has been selected as the most appropriate for the process under examination. One of the fundamenta properties of a suitable desorbent for a separation process appears to be its affinity to the adsorbent, whic must be intermediate between those of the compounds to be separated.

  4. Selective separation of protein and saccharides by ionic liquids aqueous two-phase systems

    Institute of Scientific and Technical Information of China (English)


    In the present work,it was found that aqueous solution of a hydrophilic ionic liquid (IL),1-butyl-3-methylimidazolium dicyanamide ([C4mim][N(CN)2]),could be separated into an aqueous two-phase system (ATPS) by inorganic salts such as K2HPO4 and K3PO4.The top phase is IL-rich,while the bottom phase is phosphate-rich.It was shown that 82.7%-100% bovine serum albumin (BSA) could be enriched into the top phase and almost quantitative saccharides (arabinose,glucose,sucrose,raffinose or dextran) were preferentially extracted into the bottom phase in a single-step extraction by [C4mim][N(CN)2] + K2HPO4 ATPS.The extraction efficiency of BSA from the aqueous saccharide solutions was influenced by the molecular structure of saccharides.The conductivity,dynamic light scattering (DLS) and transmission electron microscopy (TEM) were combined to investigate the microstructure of the IL-rich top phase and the possible mechanism for the selective separation.It is suggested that the formation of the IL aggregate and the IL aggregate-BSA complex plays a significant role in the separation of BSA from aqueous saccharide solutions.This is the first example for the selective separation by ILs-based ATPSs.It is expected that these findings would have potential applications in bio-analysis,separation,and IL recycle.

  5. Chiral separation of novel diazenes on a polysaccharide-based stationary phase in the reversed-phase mode. (United States)

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


    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.

  6. Effects of the Wetting Particles on Phase Separation of Binary Mixtures

    Institute of Scientific and Technical Information of China (English)

    LIU Ji-Wen; MA Yu-qiang


    We study phase separation of binary mixtures in the presence of mobile particles by the lattice Monte Carlo simulation. The presence of mobile particles changes tile morphology of the domain growth, in agreement with earlier experimental result. By varying the wetting interaction strength, we can control the speed of phase separation, and find a critical wetting strength beyond which the growth of the domains slows down. We propose a novel scaling function which describes the growth of the domain size L(t) as a function of time. It suggests an applicable way to tune the speed of phase separation by the coupling between the phase decomposition and the mobile particle-wetting process.

  7. Influence of the intermediate digestion phases of common formulation lipids on the absorption of a poorly water-soluble drug. (United States)

    Kossena, Greg A; Charman, William N; Boyd, Ben J; Porter, Christopher J H


    The influence of different model intestinal phases (modelled on those likely to be produced in vivo after the digestion of commonly used formulation lipids) on the absorption profile of cinnarizine has been studied. Combinations of C8, C12, or C18:1 fatty acid and monoglyceride and simulated endogenous intestinal fluid were formulated to provide examples of liquid (L1), lamellar (L(alpha)), and cubic (C) liquid crystalline phases. Phases containing cinnarizine were dosed intraduodenally and absorption was assessed in an anesthetized rat model. Bile duct ligation was performed to inhibit the effects of digestion/dilution on the phase structure. Absorption from the L(alpha) phases (C8 and C12 lipids) was statistically higher (p absorption. Experiments in bile intact rats with the C8 L(alpha) and C18:1 C phase highlighted that the absorption-modifying properties of these phases were influenced by dilution in the endogenous bile milieu, with absorption from L(alpha) phase reducing (possibly through precipitation of solubilized drug) and increasing in the case of the C18:1 C phase, possibly through the coexistence of L1 and C upon dilution permitting more efficient transfer of solubilized drug.

  8. Precipitation phase separation schemes in the Naqu River basin, eastern Tibetan plateau (United States)

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


    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.

  9. Characterization of fish gelatin-gum arabic complex coacervates as influenced by phase separation temperature. (United States)

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


    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.

  10. Separation performance of guanidinium-based ionic liquids as stationary phases for gas chromatography. (United States)

    Qiao, Lizhen; Lu, Kai; Qi, Meiling; Fu, Ruonong


    Room temperature ionic liquids (RTILs) as stationary phases for gas chromatography (GC) have made great achievements in both research and applications over the last decades. Until now, all of the RTIL stationary phases reported have involved imidazolium, ammonium, pyrrolidinium, and phosphonium-based RTILs, and however, no publications are available using guanidinium-based ionic liquids (GBILs) as GC stationary phases except two preliminary reports from our group. In the present work, three hexaalkyl GBILs stationary phases, namely N, N,N',N'-tetramethyl-N″, N″-dioctylguanidinum hexafluophosphate (DOTMG-PF(6)), N,N,N',N'-tetramethyl-N″, N″-dioctylguanidinium bis (trifluoromethylsulfonyl) imide (DOTMG-NTf(2)), and N,N,N',N'-tetraoctyl-N″, N″-dimethylguanidinium bis (trifluoromethylsulfonyl) imide (TODMG-NTf(2)), were synthesized and used as stationary phases for GC separation after they were statically coated onto the inner walls of fused-silica capillary columns. The evaluation of DOTMG-PF(6) and TODMG-NTf(2) as GC stationary phases is reported here for the first time, whereas additional results on the DOTMG-NTf(2) stationary phase are added here on the basis of our previous report. In this work, McReynolds constants and Abraham solvation system constants are used to evaluate the average polarity and the solvation properties of the GBILs stationary phases for GC separation, respectively. The results show that the GBILs stationary phases exhibit medium polarity with an average polarity of 293-390, and that the major molecular interactions of the GBILs with analytes are dipole/polarizable interactions, H-bond basicity and dispersion forces, etc. After this, the separation performance and thermal stability of the GBILs stationary phases were evaluated, showing that these stationary phases achieve excellent separation for analytes of great variety covering hydrocarbons, alcohols, esters, aldehydes, ketones, amines, amides and aromatics, and exhibit

  11. Three-dimensional correlated-fermion phase separation from analysis of the geometric mean of the individual susceptibilities

    Institute of Scientific and Technical Information of China (English)


    A quasi-Gaussian approximation scheme is formulated to study the strongly correlated imbalanced Fermions thermodynamics, where the mean-field theory is not applicable. The non-Gaussian correlation effects are understood to be captured by the statistical geometric mean of the individual susceptibilities. In the three-dimensional unitary fermions ground state, a universal nonlinear scaling transformation relates the physical chemical potentials with the individual Fermi kinetic energies. For the partial polarization phase separation to full polarization, the calculated critical polarization ratio is δC = [1-(1-ξ)6/5]/[1+(1-ξ )6/5] 0.34. ξ = 4/9 gives the ratio of the symmetric ground state energy density to that of the ideal fermion gas.

  12. Measuring the Transition Rates of Coalescence Events during Double Phase Separation in Microgravity

    Directory of Open Access Journals (Sweden)

    Ana Oprisan


    Full Text Available Phase transition is a ubiquitous phenomenon in nature, science and technology. In general, the phase separation from a homogeneous phase depends on the depth of the temperature quench into the two-phase region. Earth’s gravity masks the details of phase separation phenomena, which is why experiments were performed under weightlessness. Under such conditions, the pure fluid sulphur hexafluoride (SF 6 near its critical point also benefits from the universality of phase separation behavior and critical slowing down of dynamics. Initially, the fluid was slightly below its critical temperature with the liquid matrix separated from the vapor phase. A 0.2 mK temperature quench further cooled down the fluid and produced a double phase separation with liquid droplets inside the vapor phase and vapor bubbles inside the liquid matrix, respectively. The liquid droplets and the vapor bubbles respective distributions were well fitted by a lognormal function. The evolution of discrete bins of different radii allowed the derivation of the transition rates for coalescence processes. Based on the largest transition rates, two main coalescence mechanisms were identified: (1 asymmetric coalescences between one small droplet of about 20 μ m and a wide range of larger droplets; and (2 symmetric coalescences between droplets of large and similar radii. Both mechanisms lead to a continuous decline of the fraction of small radii droplets and an increase in the fraction of the large radii droplets. Similar coalescence mechanisms were observed for vapor bubbles. However, the mean radii of liquid droplets exhibits a t 1 / 3 evolution, whereas the mean radii of the vapor bubbles exhibit a t 1 / 2 evolution.

  13. Densitometric HPTLC method for qualitative, quantitative analysis and stability study of Coenzyme Q10 in pharmaceutical formulations utilizing normal and reversed-phase silica gel plates. (United States)

    Abdel-Kader, Maged Saad; Alam, Prawez; Alqasoumi, Saleh Ibrahim


    Two simple, precise and stability-indicating densitometric HPTLC method were developed and validated for qualitative and quantitative analysis of Coenzyme Q10 in pharmaceutical formulations using normal-phase (Method I) and reversed phase (Method II) silica gel TLC plates. Both methods were developed and validated with 10×20 cm glass-backed plates coated with 0.2 mm layers of either silica gel 60 F254 (E-Merck, Germany) using hexane-ethyl acetate (8.5:1.5 v/v) as developing system (Method I) or RP-18 silica gel 60 F254 (E-Merck, Germany) using methanol-acetone (4:6 v/v) as mobile phase (Method II). Both analyses were scanned with a densitometer at 282 nm. Linearity was found in the ranges 50-800 ng/spot (r(2)=0.9989) and 50-800 ng/spot (r(2)=0.9987) for Method I and Method II respectively. Stability of Coenzyme Q10 was explored by the two methods using acid, base, hydrogen peroxide, temperature and different solvents. Due to the efficiency of the method in separating Coenzyme Q10 from other ingredients including its degradation products, it can be applied for quality control, standardization of different pharmaceutical formulations and stability study.

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

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


    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. Tuning of mobile and stationary phase polarity for the separation of polar compounds by SFC. (United States)

    Ibañez, E; Señoráns, F J


    The separation of polar compounds by supercritical-fluid chromatography (SFC) is reviewed. New developments in mobile and stationary phase tuning are reviewed for packed and packed capillary SFC. In terms of mobile phase polarity adjustment, new pure and multiple component fluids are presented. The approach of tuning the polarity of the stationary phase as a way of increasing the range of polar compounds analyzed by SFC using pure CO(2) is discussed using either silica-based or new materials as stationary phase. Chiral, liquid crystal and polymer-based stationary phases coated on particles are widely covered in this review as an interesting approach to separate polar compounds avoiding the major drawbacks associated to the use of modifiers in SFC.

  16. Simulations of irradiated-enhanced segregation and phase separation in Fe-Cu-Mn alloys (United States)

    Li, Boyan; Hu, Shenyang; Li, Chengliang; Li, Qiulin; Chen, Jun; Shu, Guogang; Henager, Chuck, Jr.; Weng, Yuqing; Xu, Ben; Liu, Wei


    For reactor pressure vessel steels, the addition of Cu, Mn, and Ni has a positive effect on their mechanical, corrosion and radiation resistance properties. However, experiments show that radiation-enhanced segregation and/or phase separation is one of the important material property degradation processes. In this work, we develop a model integrating rate theory and phase-field approaches to investigate the effect of irradiation on solute segregation and phase separation. The rate theory is used to describe the accumulation and clustering of radiation defects, while the phase-field approach describes the effect of radiation defects on phase stability and microstructure evolution. The Fe-Cu-Mn ternary alloy is taken as a model system. The free energies used in the phase-field model are from CALPHAD. Spatial dependent radiation damage from atomistic simulations is introduced into the simulation cell for a given radiation dose rate. The radiation effect on segregation and phase separation is taken into account through the defect concentration dependence of solute mobility. Using the model, the effect of temperature and radiation rates on Cu and Mn segregation and Cu-rich phase nucleation were systematically investigated. The segregation and nucleation mechanisms were analyzed. The simulations demonstrate that the nucleus of Cu precipitates has a core-shell composition profile, i.e. Cu-rich at the center and Mn-rich at the interface, in good agreement with theoretical calculations as well as experimental observations.

  17. Role of vertex corrections in the matrix formulation of the random phase approximation for the multiorbital Hubbard model (United States)

    Altmeyer, Michaela; Guterding, Daniel; Hirschfeld, P. J.; Maier, Thomas A.; Valentí, Roser; Scalapino, Douglas J.


    In the framework of a multiorbital Hubbard model description of superconductivity, a matrix formulation of the superconducting pairing interaction that has been widely used is designed to treat spin, charge, and orbital fluctuations within a random phase approximation (RPA). In terms of Feynman diagrams, this takes into account particle-hole ladder and bubble contributions as expected. It turns out, however, that this matrix formulation also generates additional terms which have the diagrammatic structure of vertex corrections. Here we examine these terms and discuss the relationship between the matrix-RPA superconducting pairing interaction and the Feynman diagrams that it sums.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mohan, R.S.; Shoham, O.


    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.

  19. Simultaneous separation of hydrophobic and hydrophilic peptides with a silica hydride stationary phase using aqueous normal phase conditions. (United States)

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


    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.

  20. Thermal reversible gelation during phase separation of poly(N-isopropyl acrylamide)/water solution

    Institute of Scientific and Technical Information of China (English)

    曾钫[1; 刘新星[2; 童真[3; 杨燕银[4; 吴水珠[5


    By dynamic viscoelastic measurement for PNIPAM/water solution it has been found that below the phase separation temperature (about 32 ℃), the system is homogeneous fluid; while upon being heated to about 32 ℃, the solution undergoes phase separation and the storage modulus G’ increases sharply and exceeds the loss modulus G", indicating the physical network formation during the phase separation. Based on the percolation model, the gel points Tgel, were obtained by applying the dynamic scaling theory (DST) and winter’s criterion. The critical exponent n was also obtained to be 0.79 through DST, which is different from 0.67, the critical point of chemically crosslinked network predicted through DST. The obtained n value reflects the special property of physical network being different from chemical network.

  1. Thermal reversible gelation during phase separation of poly(N-isopropyl acrylamide)/water solution

    Institute of Scientific and Technical Information of China (English)


    By dynamic viscoelastic measurement for PNIPAM/water solution it has been found that below the phase separation temperature (about 32℃), the system is homogeneous fluid; while upon being heated to about 32℃, the solution undergoes phase separation and the storage modulus G′ increases sharply and exceeds the loss modulus G″, indicating the physical network formation during the phase separation. Based on the percolation model, the gel points Tgel were obtained by applying the dynamic scaling theory (DST) and Winter's criterion. The critical exponent n was also obtained to be 0.79 through DST, which is different from 0.67, the critical point of chemically crosslinked network predicted through DST. The obtained n value reflects the special property of physical network being different from chemical network.

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

    CERN Document Server

    Ito, Hiroaki; Shimokawa, Naofumi


    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 p...

  3. Origin of reversible photo-induced phase separation in hybrid perovskites

    CERN Document Server

    Bischak, Connor G; Wu, Hao; Aloni, Shaul; Ogletree, D Frank; Limmer, David T; Ginsberg, Naomi S


    Nonequilibrium processes occurring in functional materials can significantly impact device efficiencies and are often difficult to characterize due to the broad range of length and time scales involved. In particular, mixed halide hybrid perovskites are promising for optoelectronics, yet the halides reversibly phase separate when photo-excited, significantly altering device performance. By combining nanoscale imaging and multiscale modeling, we elucidate the mechanism underlying this phenomenon, demonstrating that local strain induced by photo-generated polarons promotes halide phase separation and leads to nucleation of light-stabilized iodide-rich clusters. This effect relies on the unique electromechanical properties of hybrid materials, characteristic of neither their organic nor inorganic constituents alone. Exploiting photo-induced phase separation and other nonequilibrium phenomena in hybrid materials, generally, could enable new opportunities for expanding the functional applications in sensing, photo...

  4. Device for two-dimensional gas-phase separation and characterization of ion mixtures (United States)

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


    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.

  5. Molecular dynamics simulations of phase separation in the presence of surfactants

    DEFF Research Database (Denmark)

    Laradji, Mohamed; Mouritsen, Ole G.; Toxvaerd, Søren


    The dynamics of phase separation in two-dimensional binary mixtures diluted by surfactants is studied by means of molecular dynamics simulations. In contrast to pure binary systems, characterized by an algebraic time dependence of the average domain size, we find that systems containing surfactants...... exhibit nonalgebraic, slow dynamics. The average domain size eventually saturates at a value inversely proportional to the surfactant concentration. We also find that phase separation in systems with different surfactant concentrations follow a crossover scaling form. Finally, although these systems do...... not fully phase separate, we observe a dynamical scaling which is independent of the surfactant concentration. The results of these simulations are in general in agreement with previous Langevin simulations [Laradji, Guo, Grant, and Zuckermann, J. Phys. A 44, L629 (1991)] and a theory of Ostwald ripening...

  6. Staged phase separation in the I-I-N tri-phase region of platelet-sphere mixtures. (United States)

    Chen, Mingfeng; He, Min; Lin, Pengcheng; Chen, Ying; Cheng, Zhengdong


    Mixtures of colloids with different sizes or shapes are ubiquitous in nature and extensively applied in industries. Phase transition pathways and kinetics in this model system should be investigated because of the difficulty in observing tri-phase coexistence in colloidal platelet-sphere mixtures. Similar to the polymer-sphere mixtures, the phase transition pathway has three main categories. Analytical results show a staged phase transition process in which the mixture first separates into one or two metastable phases, then further separates, and subsequently reaches tri-phase equilibrium. Unique to our system, and different from the gas-liquid-crystal coexistence in colloid-polymer mixtures, the platelet-sphere mixture reached a gas-liquid-liquid crystal (nematic) coexistence. Thus, the different phases are easy to distinguish using the birefringence of the liquid crystals. In addition, the volume fraction of the liquid crystal formation in the ZrP platelet suspensions is much lower than for the crystal formation in hard spheres.

  7. In-line and selective phase separation of medium-chain carboxylic acids using membrane electrolysis. (United States)

    Xu, Jiajie; Guzman, Juan J L; Andersen, Stephen J; Rabaey, Korneel; Angenent, Largus T


    We had extracted n-caproate from bioreactor broth. Here, we introduced in-line membrane electrolysis that utilized a pH gradient between two chambers to transfer the product into undissociated n-caproic acid without chemical addition. Due to the low maximum solubility of this acid, selective phase separation occurred, allowing simple product separation into an oily liquid containing ∼90% n-caproic and n-caprylic acid.

  8. Evolving neural network optimization of cholesteryl ester separation by reversed-phase HPLC


    Jansen, Michael A.; Kiwata, Jacqueline; Arceo, Jennifer; Faull, Kym F.; Hanrahan, Grady; Porter, Edith


    Cholesteryl esters have antimicrobial activity and likely contribute to the innate immunity system. Improved separation techniques are needed to characterize these compounds. In this study, optimization of the reversed-phase high-performance liquid chromatography separation of six analyte standards (four cholesteryl esters plus cholesterol and tri-palmitin) was accomplished by modeling with an artificial neural network–genetic algorithm (ANN-GA) approach. A fractional factorial design was emp...

  9. Lipid diffusion and swelling in a phase separated biocompatible thermoplastic elastomer. (United States)

    Fittipaldi, Mauro; Grace, Landon R


    Lipid uptake was analyzed via gravimetric measurements in a biocompatible poly(styrene-block-isobutylene-block-styrene) (SIBS) copolymer. Absorption followed Fickian diffusion behavior very closely, although some deviation was noticed once saturation was reached. Diffusion parameters of three different SIBS formulations were calculated and used to predict the behavior of a fourth type based on molecular weight and relative polystyrene content. SIBS with lower polystyrene content and molecular weight showed lower physical stability and developed surface cracks that propagated with exposure to the lipid medium. Saturation lipid content varied from 45% to 63% by weight and was inversely related to polystyrene content, suggesting most of the plasticization is occurring in the isobutylene phase of SIBS. Moreover, swelling of specimens was monitored throughout the immersion in the lipid medium and ranged from 32% to 58%. Swelling in formulations with lower hard phase (polystyrene) was significantly higher than the swelling in SIBS with higher hard phase content. This is consistent with lipid-induced plasticization occurring in the soft (polyisobutylene) segments, relaxing the polymer network and leading to increased swelling and lipid uptake. The biocompatibility and tailorability of SIBS through control of hard/soft phase ratio offer significant advantages for in vivo applications. However, the lipophilic nature of the material and the associated degradation may render the polymer unusable in certain applications. The predictive model of lipid uptake introduced here will allow more accurate evaluation of lipid susceptibility during the preliminary design phase of SIBS-based in vivo structures.

  10. Phase behaviors involved in surimi gel system: Effects of phase separation on gelation of myofibrillar protein and kappa-carrageenan. (United States)

    Zhang, Tao; Xu, Xiaoqi; Ji, Lei; Li, Zhaojie; Wang, Yuming; Xue, Yong; Xue, Changhu


    Phase behaviors of mixtures of myofibrillar protein and κ-carrageenan at different mixing ratios and temperatures were examined by digital images and confocal scanning laser microscopy, showing that that the extent of phase separation was enhanced as the ratio of polysaccharides and temperature increased. The zeta potential of the mixtures became less negative as the protein ratio increased, and the complex became saturated at or above the protein/κ-carrageenan ratio of R4 (3.2%:0.8%). Gelation process performed by dynamic rheological analysis demonstrated that the presence of carrageenan decreased the gelation temperature but increased the storage modulus. Analysis of the microstructures of the mixed gels showed that the networks were significantly influenced by the concentrations of κ-carrageenan. The present work could be applied to evaluate the mechanism of competition between phase separation and gelation in mixtures of proteins and polysaccharides. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Exploring the dynamics of phase separation in colloid-polymer mixtures with long range attraction. (United States)

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


    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.

  12. Liquid-liquid phase separation in aerosol particles: imaging at the nanometer scale. (United States)

    O'Brien, Rachel E; Wang, Bingbing; Kelly, Stephen T; Lundt, Nils; You, Yuan; Bertram, Allan K; Leone, Stephen R; Laskin, Alexander; Gilles, Mary K


    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 micrometer-sized particles undergoing a full hydration-dehydration cycle. Internally mixed particles composed of ammonium sulfate (AS) and either: limonene secondary organic carbon (LSOC), α, 4-dihydroxy-3-methoxybenzeneaceticacid (HMMA), or polyethylene glycol (PEG-400) were studied. Events of LLPS 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 outer phase. The outer phase 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 70:30% organic to inorganic mix in the outer phase. 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. Feedback stabilization of the Cahn-Hilliard type system for phase separation (United States)

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


    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.

  14. The interface dynamics of bicontinuous phase separating structure in a polymer blend

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Haruko; Yoshinaga, Masahiro; Mihara, Takaaki; Jinnai, Hiroshi [Department of Macromolecular Science and Engineering, Kyoto Institute of Technology, Kyoto 606-8585 (Japan); Nishi, Toshio, E-mail: [World Premier International, Advanced Institute for Materials Research, Tohoku University, Katahira, Sendai 980-8577 (Japan)


    The time evolution of the phase separating pattern during the spinodal decomposition (SD) of a specimen was observed at the same volume of the specimen using X-ray computerized microtomography (X-ray CT). A careful examination of time-dependent three-dimensional (3D) images revealed that bridge-like domains played an important role in the phase separation dynamics. In the course of the SD, some bridge-like domains became thicker, while the others became thinner. It was found that the pressure difference across the interface, which is quantified through the mean curvature of the interface, influences such interface dynamics.


    Institute of Scientific and Technical Information of China (English)

    LI Wenjun; YUAN Youxin; CABASSO,Israel


    Microporous membranes of low-high density polyethylene and their blends were prepared by thermally-induced phase separation of polymer/long-aliphatic chain alcohol (diluent)mixtures.The microstructures of this particular membrane, which depends on the diluent properties,polymer concentration and cooling rate, were observed by scanning electron microscopy."Beehive-type,"leafy-like, and lacy porous structure morphologies can be formed,depending on the blend composition and phase separation conditions, which were discussed by the polymer and diluent crystallization processes.

  16. Submicron-scale manipulation of phase separation in organic solar cells (United States)

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


    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.

  17. An atom probe perspective on phase separation and precipitation in duplex stainless steels (United States)

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


    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). ).

  18. Separation of monosaccharides by solid-phase extraction with ionic liquid-modified microporous polymers. (United States)

    Tian, Minglei; Bi, Wentao; Row, Kyung H


    Ionic liquid-modified porous polymers with large surface area and large amount of functional groups were developed and used in SPE to separate four monosaccharides. Adsorption isotherm showed that the sorbent with amino ionic liquid groups had the highest interaction with the target compounds. The mobile phase of acetonitrile/water 85:15 and 73:30 v/v can successfully separate the monosaccharides. The sorbent produced reproducible results and performed stably, demonstrating its potential applicability in the separation of extract from natural plant. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Range-separated density-functional theory with random phase approximation: detailed formalism and illustrative applications

    CERN Document Server

    Toulouse, Julien; Angyan, Janos G; Savin, Andreas


    Using Green-function many-body theory, we present the details of a formally exact adiabatic-connection fluctuation-dissipation density-functional theory based on range separation, which was sketched in Toulouse, Gerber, Jansen, Savin and Angyan, Phys. Rev. Lett. 102, 096404 (2009). Range-separated density-functional theory approaches combining short-range density functional approximations with long-range random phase approximations (RPA) are then obtained as well-identified approximations on the long-range Green-function self-energy. Range-separated RPA-type schemes with or without long-range Hartree-Fock exchange response kernel are assessed on rare-gas and alkaline-earth dimers, and compared to range-separated second-order perturbation theory and range-separated coupled-cluster theory.

  20. Phase separation kinetics in amorphous solid dispersions upon exposure to water. (United States)

    Purohit, Hitesh S; Taylor, Lynne S


    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.

  1. Parametric study on phase separation of binary mixtures in a lid driven cavity: A DPD study (United States)

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


    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.

  2. Structural Characterization of Phase Separation in Fe-Cr: A Current Comparison of Experimental Methods (United States)

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


    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.

  3. Impact of backmixing of the aqueous phase on two-component rare earth separation process

    Institute of Scientific and Technical Information of China (English)

    WU Sheng; CHENG Fuxiang; LIAO Chunsheng; YAN Chunhua


    Solvent extraction based on mixer-settler is the major industrial method of rare earth (RE) separation.In the mixer-settler extraction process,due to the insufficient settling time in normal circumstances,backmixing of the aqueous phase could have significant impact on the process of RE extraction separation.Therefore on the basis of the extraction equilibrium and mass balance of the mixer-settler extraction process,here we developed a mathematic expression of the aqueous phase backmixing in a two-component separation process,and obtained a quantitative analysis of the backmixing effect on the purification process by the approximations according to certain hypotheses.Two extraction systems of La/Ce and Pr/Nd separation were chosen as the examples to analyze the backmixing effect,and the results showed that the aqueous backmixing had greater influence in the scrubbing segment than in the extraction segment,especially in the system with a high separation factor such as La/Ce separation.Therefore it was suggested that the aqueous backmixing effect should be well attended in the design and application of RE extraction separation.

  4. Interlamellar Organization of Phase Separated Domains in Multi-Component Lipid Multilayers: Energetic Considerations

    Directory of Open Access Journals (Sweden)

    Daryoosh Vashaee


    Full Text Available A recent experimental study [1] has demonstrated the alignment of phase separated domains across hundreds of bilayer units in multicomponent stacked lipid bilayers. The origin of this alignment is the interlamellar coupling of laterally phase separated domains. Here, we develop a theoretical model that presents the energetics description of this phenomenon based on the minimization of the free energy of the system. Specifically, we use solution theory to estimate the competition between energy and entropy in different stacking configurations. The model furnishes an elemental phase diagram, which maps the domain distributions in terms of the strength of the intra- and inter-layer interactions and estimates the value of inter-layer coupling for complete alignment of domains in the stacks of five and ten bilayers. The area fraction occupied by co-existing phases was calculated for the system of the minimum free energy, which showed a good agreement with experimental observations.

  5. Quantitation of low concentrations of polysorbates in high protein concentration formulations by solid phase extraction and cobalt-thiocyanate derivatization. (United States)

    Kim, Justin; Qiu, Jinshu


    A spectrophotometric method was developed to quantify low polysorbate (PS) levels in biopharmaceutical formulations containing high protein concentrations. In the method, Oasis HLB solid phase extraction (SPE) cartridge was used to extract PS from high protein concentration formulations. After loading a sample, the cartridge was washed with 4M guanidine HCl and 10% (v/v) methanol, and the retained PS was eluted by acetonitrile. Following the evaporation of acetonitrile, aqueous cobalt-thiocyanate reagent was added to react with the polyoxyethylene oxide chain of polysorbates to form a blue colored PS-cobaltothiocyante complex. This colored complex was then extracted into methylene chloride and measured spectrophotometrically at 620 nm. The method performance was evaluated on three products containing 30-40 mg L(-1) PS-20 and PS-80 in ≤70 g L(-1) protein formulations. The method was specific (no matrix interference identified in three types of protein formulations), sensitive (quantitation limit of 10 mg L(-1) PS) and robust with good precision (relative standard deviation ≤6.4%) and accuracy (spike recoveries from 95% to 101%). The linear range of the method for both PS-20 and PS-80 was 10 to 80 mg L(-1) PS. By diluting samples with 6M guanidine HCl and/or using different methylene chloride volumes to extract the colored complexes of standards and samples, the method could accurately and precisely quantify 40 mg L(-1) PS in up to 300 g L(-1) protein formulations.

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

    Energy Technology Data Exchange (ETDEWEB)

    Girard, Steven N. [Northwestern University; Schmidt-Rohr, Klaus [Ames Laboratory; Chasapis, Thomas C. [Northwestern University; Hatzikraniotis, Euripides [Aristotle University of Thessaloniki; Njegic, B. [Ames Laboratory; Levin, E. M. [Ames Laboratory; Rawal, A. [Ames Laboratory; Paraskevopoulos, Konstantios M. [Aristotle University of Thessaloniki; Kanatzidis, Mercouri G. [Northwestern University


    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.

  7. Morphology and Performance of PLLA Based Porous Membranes by Phase Separation Control (United States)

    Xing, Qian; Dong, Xia; Li, Rongbo; Han, Charles C.; Wang, Dujin


    Poly (L-lactic acid) (PLLA) porous membranes with different morphologies and properties were prepared through immersion precipitation method. It has been proved that the rate and level of phase separation between PLLA/dioxane solution and coagulation baths were the original drive force for the ultimate structure and corresponding performance of PLLA membranes. The equilibrium thermodynamic phase diagram of PLLA/solvent/nonsolvent and the kinetic diffusion rate between solvent and nonsolvent were systematically investigated. NSFC 50925313 and 51173195

  8. Enantiomeric Separation of Four Chiral Compounds Using Immobilized Cellulose 3, 5-Dimethylphenylcarbamate as Chiral Stationary Phase

    Institute of Scientific and Technical Information of China (English)

    Yong Fei MING; Liang ZHAO; Hong Li ZHANG; Yan Ping SHI; Yong Min LI; Li Ren CHEN


    A new chiral stationary phase of 3, 5-dimethylphenylcarbamates of cellulose,chemically bonded to 3-aminopropylsilica gel at the 6-positions of the glucose units, was prepared.The solvent versatility of the CSP was investigated for the enantioselective separation of four pairs of enantiomers using THF and chloroform as non-standard mobile phase eluent in HPLC. The influence of temperature on the resolution was investigated.

  9. Phase field modeling of brittle fracture for enhanced assumed strain shells at large deformations: formulation and finite element implementation (United States)

    Reinoso, J.; Paggi, M.; Linder, C.


    Fracture of technological thin-walled components can notably limit the performance of their corresponding engineering systems. With the aim of achieving reliable fracture predictions of thin structures, this work presents a new phase field model of brittle fracture for large deformation analysis of shells relying on a mixed enhanced assumed strain (EAS) formulation. The kinematic description of the shell body is constructed according to the solid shell concept. This enables the use of fully three-dimensional constitutive models for the material. The proposed phase field formulation integrates the use of the (EAS) method to alleviate locking pathologies, especially Poisson thickness and volumetric locking. This technique is further combined with the assumed natural strain method to efficiently derive a locking-free solid shell element. On the computational side, a fully coupled monolithic framework is consistently formulated. Specific details regarding the corresponding finite element formulation and the main aspects associated with its implementation in the general purpose packages FEAP and ABAQUS are addressed. Finally, the applicability of the current strategy is demonstrated through several numerical examples involving different loading conditions, and including linear and nonlinear hyperelastic constitutive models.

  10. Phase field modeling of brittle fracture for enhanced assumed strain shells at large deformations: formulation and finite element implementation (United States)

    Reinoso, J.; Paggi, M.; Linder, C.


    Fracture of technological thin-walled components can notably limit the performance of their corresponding engineering systems. With the aim of achieving reliable fracture predictions of thin structures, this work presents a new phase field model of brittle fracture for large deformation analysis of shells relying on a mixed enhanced assumed strain (EAS) formulation. The kinematic description of the shell body is constructed according to the solid shell concept. This enables the use of fully three-dimensional constitutive models for the material. The proposed phase field formulation integrates the use of the (EAS) method to alleviate locking pathologies, especially Poisson thickness and volumetric locking. This technique is further combined with the assumed natural strain method to efficiently derive a locking-free solid shell element. On the computational side, a fully coupled monolithic framework is consistently formulated. Specific details regarding the corresponding finite element formulation and the main aspects associated with its implementation in the general purpose packages FEAP and ABAQUS are addressed. Finally, the applicability of the current strategy is demonstrated through several numerical examples involving different loading conditions, and including linear and nonlinear hyperelastic constitutive models.

  11. Stress reduction in phase-separated, cross-linked networks: influence of phase structure and kinetics of reaction. (United States)

    Szczepanski, Caroline R; Stansbury, Jeffrey W


    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.

  12. Hydrodynamic effects on phase separation morphologies in evaporating thin films of polymer solutions (United States)

    Zoumpouli, Garyfalia A.; Yiantsios, Stergios G.


    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

  13. Selective Separation of Fe-Concentrates in EAF Slags Using Mechanical Dissimilarity of Solid Phases (United States)

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


    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.

  14. Validation and application of reversed phase high-performance liquid chromatographic method for quantification of pizotifen malate in pharmaceutical solid dosage formulations. (United States)

    Rahman, Shaikh Mukidur; Lutfulkabir, Abulkalam; Jahan, M D Arshad; Momen, A Z M Ruhul; Rouf, Abushara Shamsur


    The aim of this study was to develop and validate an isocratic reversed phase high-performance liquid chromatographic method for quantification of pizotifen malate in pharmaceutical solid dosage formulations. Good chromatographic separation of pizotifen malate was achieved by using an analytical column, C(18) ODS column. The system was operated at 40°C oven temperature using a mobile phase consisting of acetonitrile and acetate buffer pH 7.0 (60:40) at a flow rate of 2 ml/min. The method showed high sensitivity with good linearity (r(2)= 0.99997) over the tested concentration range of 0.0020-0.0300 mg/ml for pizotifen malate. Detection was carried out at 231 nm and retention time was 2.838 min. Placebo and blank studies were performed and no peak was observed at the retention time of pizotifen malate. The intermediate precision and accuracy results (mean ± RSD, n=3) were (99.11±0.21) % and (99.19±0.55) % respectively with tailing factor (1.26±0.19). The proposed method was validated in terms of selectivity, linearity, accuracy, precision, range, detection and quantitation limit, system suitability and solution stability.This method can be successfully employed for simultaneous quantitative analysis of pizotifen malate in pharmaceutical solid dosage formulations.

  15. $p$-th Clustering coefficients and $q$-$th$ degrees of separation based on String-Adjacent Formulation

    CERN Document Server

    Toyota, Norihito


    The phenomenon of six degrees of separation is an old but attractive subject. The deep understanding has been uncovered yet, especially how closed paths included in a network affect six degrees of separation are an important subject left yet. For it, some researches have been made\\cite{Newm21}, \\cite{Aoyama}. Recently we have develop a formalism \\cite{Toyota3},\\cite{Toyota4} to explore the subject based on the string formalism developed by Aoyama\\cite{Aoyama}. The formalism can systematically investigate the effect of closed paths, especially generalized clustering coefficient $C_{(p)}$ introduced in \\cite{Toyota4}, on six degrees of separation. In this article, we analyze general $q$-th degrees of separation by using the formalism developed by us. So we find that the scale free network with exponent $\\gamma=3$ just display six degrees of separation. Furthermore we drive a phenomenological relation between the separation number $q$ and $C_{(p)}$ that has crucial information on circle structures in networks.

  16. Development of optimized mobile phases for protein separation by high performance thin layer chromatography. (United States)

    Biller, Julia; Morschheuser, Lena; Riedner, Maria; Rohn, Sascha


    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. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Stability and phase separation in mixed monopolar lipid/bolalipid layers. (United States)

    Longo, Gabriel S; Thompson, David H; Szleifer, I


    The phase stability of a fluid lipid layer that is a mixture of conventional monopolar lipids and C20 bipolar bolalipids was studied using a mean field theory that explicitly includes molecular details and configurational properties of the lipid molecules. The effect of changing the fraction of bolalipids, as well as the length of the hydrocarbon chain of the monopolar lipids, was probed. A phase separation between two liquid lipid phases was found when a mismatch exists in the optimal hydrophobic thicknesses of the pure bolalipid and monopolar lipid layers. The lipid mixture phase separates into a thin bolalipid-rich layer and a thicker monopolar-rich layer. The thin membrane phase is mainly composed of transmembrane bolalipid molecules whose polar heads are positioned at opposite membrane-water interfaces. In the monopolar lipid-rich phase, bolalipids are the minor component and most of them assume a looping configuration where both headgroups are present at the same membrane-water interface. For mixed layers that form a single lipid phase across all bolalipid concentrations, the hairpin-transmembrane ratio strongly depends on the hydrocarbon chain length of the monopolar lipid and the bolalipid concentration. The C-D bond order parameters of the different species have been calculated. Our findings suggest that the concentration-dependent phase transition should be experimentally observable by measuring of the order parameters through quadrupolar splitting experiments. The driving force for the phase separation in the monopolar lipid/bolalipid mixture is the packing mismatch between hydrophobic regions of the monopolar lipid hydrocarbon chains and the membrane-spanning bolalipid chains. The results from the molecular theory may be useful in the design of stable lipid layers for integral membrane protein sensing.

  18. Retention Time and Depolarization in Organic Nonvolatile Memories Based on Ferroelectric Semiconductor Phase-Separated Blends

    NARCIS (Netherlands)

    Asadi, Kamal; Wildeman, Jurjen; Blom, Paul W. M.; de Leeuw, Dago M.


    Resistive switches have been fabricated using a phase-separated blend film of ferroelectric random copolymer poly(vinylidene fluoride-co-trifluoroethylene) with the organic semiconductor regio-irregular poly(3-hexylthiophene) (rir-P3HT). Spin-coated blend films have been contacted with symmetrical A

  19. Retention time and depolarization in organic nonvolatile memories based on ferroelectric semiconductor phase-separated blends

    NARCIS (Netherlands)

    Asadi, K.; Wildeman, J.; Blom, P.W.M.; Leeuw, D.M. de


    Resistive switches have been fabricated using a phase-separated blend film of ferroelectric random copolymer poly(vinylidene fluoride-co-trifluoroethylene) with the organic semiconductor regio-irregular poly(3-hexylthiophene) (rir-P3HT). Spin-coated blend films have been contacted with symmetrical A

  20. Calculation of noise distribution in mesoscopic dynamics models for phase separation of multicomponent complex fluids

    NARCIS (Netherlands)

    vanVlimmeren, BAC; Fraaije, JGEM


    We present a simple method for the numerical calculation of the noise distribution in multicomponent functional Langevin models. The topic is of considerable importance, in view of the increased interest in the application of mesoscopic dynamics simulation models to phase separation of complex

  1. Predictions of Phase Separation in Three-Component Lipid Membranes by the MARTINI Force Field

    DEFF Research Database (Denmark)

    Davis, Ryan S.; Sunil Kumar, P. B.; Sperotto, Maria Maddalena;


    PCs, such as dilinoleyl-phosphatidylcholine (DUPC) and diarachidonoyl-phosphatidylcholine (DAPC). Through systematic tweaking of the interactions between the hydrophobic groups of the PC molecules, we show that the appearance of phase separation in three-component lipid bilayers, as modeled through...

  2. Anisotropic imprint of amorphization and phase separation in manganite thin films via laser interference irradiation

    KAUST Repository

    Ding, Junfeng


    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(Ca0.75Sr0.25)0.35MnO3 (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.

  3. Correlating structure with fluorescence emission in phase-separated conjugated-polymer blends. (United States)

    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


    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.

  4. Spinodal phase separation in semi-interpenetrating polymer networks - polystyrene-cross-polymethacrylate

    NARCIS (Netherlands)

    Graaf, de Leontine A.; Beyer, Jenö; Möller, Martin


    Morphology control in semi-interpenetrating polymer networks has been achieved by means of a two-step process, separating morphology formation and polymerization/crosslinking. Phase textures formed during spinodal liquid/liquid demixing of a solution of atactic polystyrene in methacrylate monomers w

  5. Process Intensification. Continuous Two-Phase Catalytic Reactions in a Table-Top Centrifugal Contact Separator

    NARCIS (Netherlands)

    Kraai, Gerard N.; Schuur, Boelo; van Zwol, Floris; Haak, Robert M.; Minnaard, Adriaan J.; Feringa, Ben L.; Heeres, Hero J.; de Vries, Johannes G.; Prunier, ML


    Production of fine chemicals is mostly performed in batch reactors. Use of continuous processes has many advantages which may reduce the cost of production. We have developed the use of centrifugal contact separators (CCSs) for continuous two-phase catalytic reactions. This equipment has previously

  6. Attractions in sterically stabilized silica dispersions : II. Experiments on phase separation induced by temperature variation

    NARCIS (Netherlands)

    Jansen, J.W.; Kruif, C.G. de; Vrij, A.


    On lowering the temperature initially homogeneous dispersions (in a variety of solvents) of silica coated with octadecyl chains show a separation into two phases of different concentration. The temperature of first instability is not strongly correlated with the solubility parameter of the solvent.

  7. The microstructure and rheology of homogeneous and phase separated gelatine gels

    NARCIS (Netherlands)

    Ersch, C.; Linden, E. van der; Venema, P.; Martin, A.


    The gelation of gelatine in mixtures of gelatine (type A or type B) and globular proteins (Whey Protein Isolate (WPI), Whey Protein Aggregates (WPA) and Soy Protein Isolate (SPI)) was studied with a focus on their phase separation during gelation. Confocal laser scanning microscopy, visual observati

  8. The microstructure and rheology of homogeneous and phase separated gelatine gels

    NARCIS (Netherlands)

    Ersch, Carsten; Linden, van der Erik; Venema, Paul; Martin, Anneke


    The gelation of gelatine in mixtures of gelatine (type A or type B) and globular proteins (Whey Protein Isolate (WPI), Whey Protein Aggregates (WPA) and Soy Protein Isolate (SPI)) was studied with a focus on their phase separation during gelation. Confocal laser scanning microscopy, visual observ

  9. A Classroom Demonstration of Water-Induced Phase Separation of Alcohol-Gasoline Biofuel Blends (United States)

    Mueller, Sherry A.; Anderson, James E.; Wallington, Timothy J.


    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…

  10. Structure of phase-separated ferroelectric/ semiconducting polymer blends for organic non-volatile memories

    NARCIS (Netherlands)

    Mcneill, C.R.; Asadi, K.; Watts, B.; Blom, P.W.M.; Leeuw, D.M. de


    The phase-separated structure of blends of the ferroelectric polymer P(VDF-TrFE) and the semiconducting polymer P3HT used in organic non-volatile memories is revealed with soft X-ray spectromicroscopy. These thin-film blends show a columnar morphology, with P3HT-rich columns enclosed in a continuous

  11. Preparing poly (caprolactone) micro-particles through solvent-induced phase separation

    DEFF Research Database (Denmark)

    Li, Xiaoqiang; Kanjwal, Muzafar Ahmed; Stephansen, Karen


    Poly (caprolactone) (PCL) particles with the size distribution from 1 to 100 μm were prepared through solvent-induced phase separation, in which polyvinyl-alcohol (PVA) was used as the matrix-forming polymer to stabilize PCL particles. The cloud point data of PCL-acetone-water was determined...

  12. Structural studies of the phase separation of amorphous FexGe100-x alloys (United States)

    Lorentz, Robert D.; Bienenstock, Arthur; Morrison, Timothy I.


    Small-angle x-ray scattering and x-ray-absorption near-edge spectroscopy (XANES) experiments have been performed on amorphous FexGe100-x alloys over the composition range 0Janot for the related FexSn100-x system. This phase separation explains the Mossbauer observation of ``magnetic'' and ``nonmagnetic'' Fe atoms in these alloys.

  13. A Classroom Demonstration of Water-Induced Phase Separation of Alcohol-Gasoline Biofuel Blends (United States)

    Mueller, Sherry A.; Anderson, James E.; Wallington, Timothy J.


    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…

  14. Polyurethane scaffold formation via a combination of salt leaching and thermally induced phase separation

    NARCIS (Netherlands)

    Heijkants, R. G. J. C.; van Calck, R. V.; van Tienen, T. G.; de Groot, J. H.; Pennings, A. J.; Buma, P.; Veth, R. P. H.; Schouten, A. J.


    Porous scaffolds have been made from two polyurethanes based on thermally induced phase separation of polymer dissolved in a DMSO/water mixture in combination with salt leaching. It is possible to obtain very porous foams with a very high interconnectivity. A major advantage of this method is that

  15. Separating the strengthening phase in nickel-cobalt alloys doped with tantalum (United States)

    Shaipov, R. Kh.; Kerimov, E. Yu.; Slyusarenko, E. M.


    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. Controlled phase gates based on two nonidentical quantum dots trapped in separate cavities

    Institute of Scientific and Technical Information of China (English)

    Wang Xiao-Xia; Zhang Jian-Qi; Yu Ya-Fei; Zhang Zhi-Ming


    We propose a scheme for realizing two-qubit controlled phase gates on two nonidentical quantum dots trapped in separate cavities.In our scheme,each dot simultaneously interacts with one highly detuned cavity mode and two strong driven classical fields.During the gate operation,the quantum dots undergo no transition,while the system can acquire different phases conditional on different states of the quantum dots.With the application of the single-qubit operations,two-qubit controlled phase gates can be realized.

  17. Optical transfer function analysis of circular-pupil wavefront coding systems with separable phase masks

    Institute of Scientific and Technical Information of China (English)

    Zhao Ting-Yu; Liu Qin-Xiao; Yu Fei-Hong


    This paper proposes a simple method to achieve the optical transfer function of a circular pupil wavefront coding system with a separable phase mask in Cartesian coordinates.Based on the stationary phase method,the optical transfer function of the circular pupil system can be easily obtained from the optical transfer function of the rectangular pupil system by modifying the cut-off frequency and the on-axial modulation transfer function.Finally,a system with a cubic phase mask is used as an example to illustrate the way to achieve the optical transfer function of the circular pupil system from the rectangular pupil system.

  18. Effective protein separation by coupling hydrophobic interaction and reverse phase chromatography for top-down proteomics. (United States)

    Xiu, Lichen; Valeja, Santosh G; Alpert, Andrew J; Jin, Song; Ge, Ying


    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.

  19. Evolving neural network optimization of cholesteryl ester separation by reversed-phase HPLC. (United States)

    Jansen, Michael A; Kiwata, Jacqueline; Arceo, Jennifer; Faull, Kym F; Hanrahan, Grady; Porter, Edith


    Cholesteryl esters have antimicrobial activity and likely contribute to the innate immunity system. Improved separation techniques are needed to characterize these compounds. In this study, optimization of the reversed-phase high-performance liquid chromatography separation of six analyte standards (four cholesteryl esters plus cholesterol and tri-palmitin) was accomplished by modeling with an artificial neural network-genetic algorithm (ANN-GA) approach. A fractional factorial design was employed to examine the significance of four experimental factors: organic component in the mobile phase (ethanol and methanol), column temperature, and flow rate. Three separation parameters were then merged into geometric means using Derringer's desirability function and used as input sources for model training and testing. The use of genetic operators proved valuable for the determination of an effective neural network structure. Implementation of the optimized method resulted in complete separation of all six analytes, including the resolution of two previously co-eluting peaks. Model validation was performed with experimental responses in good agreement with model-predicted responses. Improved separation was also realized in a complex biological fluid, human milk. Thus, the first known use of ANN-GA modeling for improving the chromatographic separation of cholesteryl esters in biological fluids is presented and will likely prove valuable for future investigators involved in studying complex biological samples.

  20. Comparative Optical Separation of Racemic Ibuprofen by Using Chiral Stationary Phase

    Institute of Scientific and Technical Information of China (English)

    Dalkeun; PARK; Joong; Kee; LEE; 等


    Ibprofen is widely used as a non-steroidal anti-inflammatory drug and poduced as racemic mixture.Its pharmacological activity resides only is S-(+)-enantiomer,and R-(-)-enantiomer is not only inactive but also has many side effects.Thus it is necessary to separate Renantiomer from racemic ibuprofen.We studied optical separation of racemic Ibuprofen with chiral high performance liquid chromatography(HPLC).,Out of three different chiral stationary phases,which were selected on the basis of structure and availability,two were found to be effective.There was optimum eluent composition for each stationary phase for good resolution in optical separation.Resolution decreased with increase of eluent flow rate,but effect of injection volume on resolution was insignificant at high eluent flow rate.

  1. Direct observation of mesoscopic phase separation in KxFeySe2 by scanning microwave microscopy (United States)

    Maeda, Atsutaka; Takahashi, Hideyuki; Imai, Yoshinori


    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.

  2. Rapid separation and determination of process-related substances of paracetamol using reversed-phase HPLC with photo diode array as a detector. (United States)

    Rao, R Nageswara; Narasaraju, A


    A simple and rapid gradient reversed-phase high-performance liquid chromatographic method for simultaneous separation and determination of paracetamol and its related compounds in bulk drugs and pharmaceutical formulations has been developed. As many as nine process impurities and one degradation product of paracetamol have been separated on a Symmetry C18 column (4.6 x 250 mm i.d., particle size 5 microm) with gradient elution using 0.01 M potassium dihydrogen phosphate buffer (pH 3.0) and acetonitrile as mobile phase and photo diode array detection at 215 nm. The chromatographic behavior of all the compounds was examined under variable compositions of different solvents, temperatures, buffer concentrations and pH values. The correlation coefficients for calibration curves for paracetamol as well as impurities were in the range of 0.9951 - 0.9994. The proposed RP-LC method was successfully applied to the analysis of commercial formulations; the recoveries of paracetamol were in the range of 99-101%. The method could be of use not only for rapid and routine evaluation of the quality of paracetamol in bulk drug manufacturing units but also for detection of its impurities in pharmaceutical formulations.

  3. Phase separation of electrons strongly coupled with phonons in cuprates and manganites (United States)

    Alexandrov, Sasha


    Recent advanced Monte Carlo simulations have not found superconductivity and phase separation in the Hubbard model with on-site repulsive electron-electron correlations. I argue that microscopic phase separations in cuprate superconductors and colossal magnetoresistance (CMR) manganites originate from a strong electron-phonon interaction (EPI) combined with unavoidable disorder. Attractive electron correlations, caused by an almost unretarded EPI, are sufficient to overcome the direct inter-site Coulomb repulsion in these charge-transfer Mott-Hubbard insulators, so that low energy physics is that of small polarons and small bipolarons. They form clusters localized by disorder below the mobility edge, but propagate as the Bloch states above the mobility edge. I identify the Froehlich EPI as the most essential for pairing and phase separation in superconducting layered cuprates. The pairing of oxygen holes into heavy bipolarons in the paramagnetic phase (current-carrier density collapse (CCDC)) explains also CMR and high and low-resistance phase coexistence near the ferromagnetic transition of doped manganites.

  4. Characteristics of phase transition and separation in a In-Ge-Sb-Te system (United States)

    Park, Sung Jin; Jang, Moon Hyung; Park, Seung-Jong; Cho, Mann-Ho; Ko, Dae-Hong


    In-doped GeSbTe films were deposited by ion beam sputtering deposition (IBSD) using Ge2Sb2Te5 (GST) and In3Sb1Te2 (IST) as targets. The phase change characteristics of the resulting films were then investigated by electrical measurements, including static testing, in situ 4-point Rs measurements, X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. The threshold voltage of the films increased, with increasing levels of IST. This phenomenon is consistent with the increased crystallization temperature in X-ray data and in situ 4-point Rs data. In addition, in In28Ge12Sb26Te34, multiple Vth values with a stepwise change are observed. The minimum time for the crystallization of InGeSbTe films was shorter than that for GST. X-ray data and Raman data for the crystalline structure show that phase separation to In2Te3 occurred in all of the InGeSbTe samples after annealing at 350 °C. Moreover, in the case of InGeSbTe films with high concentrations of In (28 at.%), Sb phase separation was also observed. The observed phases indicate that the origin of the phase separation of InGeSbTe films is from the enthalpy change of formation and differences in Ge-Te, In-Te, Sb-Te, In-Sb and In-In bond energies.

  5. Preparation and Characterization of Membranes Formed by Nonsolvent Induced Phase Separation: A Review

    KAUST Repository

    Guillen, Gregory R.


    The methods and mechanisms of nonsolvent induced phase separation have been studied for more than fifty years. Today, phase inversion membranes are widely used in numerous chemical industries, biotechnology, and environmental separation processes. The body of knowledge has grown exponentially in the past fifty years, which suggests the need for a critical review of the literature. Here we present a review of nonsolvent induced phase separation membrane preparation and characterization for many commonly used membrane polymers. The key factors in membrane preparation discussed include the solvent type, polymer type and concentration, nonsolvent system type and composition, additives to the polymer solution, and film casting conditions. A brief introduction to membrane characterization is also given, which includes membrane porosity and pore size distribution characterization, membrane physical and chemical properties characterization, and thermodynamic and kinetic evaluation of the phase inversion process. One aim of this review is to lay out the basics for selecting polymer solvent nonsolvent systems with appropriate film casting conditions to produce membranes with the desired performance, morphology, and stability, and to choose the proper way to characterize these properties of nonsolvent induced phase inversion membranes. © 2011 American Chemical Society.

  6. Formation of asymmetrical structured silica controlled by a phase separation process and implication for biosilicification.

    Directory of Open Access Journals (Sweden)

    Jia-Yuan Shi

    Full Text Available 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(OCH2CH34 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.

  7. Eco-friendly separation of catechins using cyclodextrins as mobile phase additives in RP-HPLC. (United States)

    Bi, Wentao; Li, Shengnan; Row, Kyung Ho


    New mobile phases for RP-HPLC were developed for the separation of catechin compounds in tea. Cyclodextrin mobile phase additives decreased the use of toxic and inflammable organic solvents without compromising resolution or separation efficiency. To develop a simple greener method for analyzing five tea catechins in RP-HPLC, the mobile phase condition was optimized and the lowest organic modifier proportion with content resolutions and retention factors were obtained. Eco-friendly cyclodextrins were used as mobile phase additives to decrease the proportion of organic modifier and improve resolutions and retention factors. The effects of several physico-chemical parameters on the retention factors were investigate d and the optimum conditions were obtained on a conventional C₁₈ column, where the mobile phase consisted of acetonitrile/water (12/88, v/v) with 1.5 mmol/L β-cyclodextrin at a flow rate of 1.0 mL/min. Cyclodextrins can separate analytes through host-guest complexation, where a transient diastereomeric complex is formed between the cyclodextrin and the analyte. β-Cyclodextrin is the most accessible, the least expensive and generally the most useful cyclodextrin. This work developed a simple eco-friendly method with the lowest concentration of organic solvents. Under the optimal condition, five catechins could be baseline separated within 17 minutes in the isocratic mode. This research exhibited the potential for the separation and determination of other active compounds from natural plants by a greener method. Copyright © 2011 John Wiley & Sons, Ltd.

  8. Asymmetrical phase separation and gelation in binary mixtures of oppositely charged colloids (United States)

    Zong, Yiwu; Yuan, Guangcui; Han, Charles C.


    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.

  9. Selective separation and enrichment of proteins in aqueous two-phase extraction system

    Institute of Scientific and Technical Information of China (English)

    Feng Qu; Hao Qin; Min Dong; Dong Xu Zhao; Xin Ying Zhao; Jing Hua Zhang


    A simple aqueous two-phase extraction system(ATPS)of PEG/phosphate was proposed for selective separation and enrichment of proteins.The combination of ATPE with HPLC was applied to identify the partition of proteins in two phases.Five proteins (bovine serum albumin,Cytochrome C,lysozyme,myoglobin,and trypsin)were used as model proteins to study the effect of phosphate concentration and pH on proteins partition.The PEG/phosphate system was firstly applied to real human saliva and plasma samples,some proteins showed obviously different partition in two phases.The primary results manifest the selective separation and enrichment of proteins in ATPS provided the potential for high abundance proteins depletion in proteomics.

  10. Supercooling transition in phase separated manganite thin films: An electrical transport study (United States)

    Singh, Sandeep; Kumar, Pawan; Siwach, P. K.; Tyagi, Pawan Kumar; Singh, H. K.


    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, La5/8-yPryCa3/8MnO3 (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.

  11. Ionic Liquids as Mobile Phase Additives for Separation of Nucleotides in High-Performance Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)

    ZHANG,Wen-Zhu(张文珠); HE,Li-Jun(何丽君); LIU,Xia(刘霞); JIANG,Sheng-Xiang(蒋生祥)


    Ionic liquids are a type of salts that are liquid at low temperature (< 100 ℃). Because of their some special properties, they have been widely used as new "green solvents" for many chemical reactions and liquid-liquid extraction in the past several years. In this paper, a new method for the separation of nucleotides is developed and the essential feature of the method is that 1-alkyl-3-methylimidazolium salts are used as mobile phase additives, resulting in a baseline separation of nucleotides without need of gradient elution and need of organic solvent addition as currently used in RP-HPLC. This study shows the potential application of ionic liquids as mobile phase additives in reversed-phase liquid chromatography.

  12. Separation of selected stable isotopes by liquid-phase thermal diffusion and by chemical exchange (United States)

    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.

  13. Unconventional magnetic phase separation in γ -CoV2O6 (United States)

    Shen, L.; Jellyman, E.; Forgan, E. M.; Blackburn, E.; Laver, M.; Canévet, E.; Schefer, J.; He, Z.; Itoh, M.


    We have explored the magnetism in the nongeometrically frustrated spin-chain system γ -CoV2O6 which possesses a complex magnetic exchange network. Our neutron diffraction patterns at low temperatures (T ≤TN=6.6 K) are best described by a model in which two magnetic phases coexist in a volume ratio 65(1) : 35(1), with each phase consisting of a single spin modulation. This model fits previous studies and our observations better than the model proposed by Lenertz et al. [J. Phys. Chem. C 118, 13981 (2014), 10.1021/jp503389c], which consisted of one phase with two spin modulations. By decreasing the temperature from TN, the minority phase of our model undergoes an incommensurate-commensurate lock-in transition at T*=5.6 K. Based on these results, we propose that phase separation is an alternative approach for degeneracy-lifting in frustrated magnets.

  14. Automation of the isotopic separation of hydrogen through gas chromatography; Automatisation des procedes de separation isotopique des hydrogenes par chromatographie en phase gazeuse

    Energy Technology Data Exchange (ETDEWEB)

    Laquerbe, C.; Steimetz, J.; Demoment, J. [CEA Valduc, 21 - Is-sur-Tille (France); Leterq, D. [CEA Bruyeres-le-Chatel, 91 (France)


    The thermal cycling absorption process (TCAP) is a separation technique that can be considered as an evolution of the discontinuous chromatography in gaseous phase used in Cea-Dam for the isotopic separation of tritium. The shift in affinity of the palladium for the 3 hydrogen isotopes allows their separation. In the TCAP process we use the shift of the separation property in terms of operating temperatures: the ability to separate is significant at the ambient temperature while it is almost zero over 1000 C degrees. Preliminary studies have allowed the selection of palladium deposits on alumina as lining. 2 pilot installations have been designed. (A.C.)

  15. Hygroscopic and phase separation properties of ammonium sulfate/organic/water ternary solutions (United States)

    Zawadowicz, M. A.; Proud, S. R.; Seppalainen, S. S.; Cziczo, D. J.


    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.

  16. Hygroscopic and phase separation properties of ammonium sulfate/organics/water ternary solutions (United States)

    Zawadowicz, M. A.; Proud, S. R.; Seppalainen, S. S.; Cziczo, D. J.


    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.

  17. Hygroscopic and phase separation properties of ammonium sulfate/organic/water ternary solutions

    Directory of Open Access Journals (Sweden)

    M. A. Zawadowicz


    Full Text Available 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.

  18. Separation of basic compounds by capillary electrochromatography on an X-Terra RP18 stationary phase. (United States)

    Valette, J C; Bizet, A C; Demesmay, C; Rocca, J L; Verdon, E


    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.

  19. Investigation of phase separation behavior and formation of plasmonic nanocomposites from polypeptide-gold nanorod nanoassemblies. (United States)

    Huang, Huang-Chiao; Nanda, Alisha; Rege, Kaushal


    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 (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. Phase separation and rapid solidification of liquid Cu60Fe30Co10 ternary peritectic alloy

    Institute of Scientific and Technical Information of China (English)

    DAI FuPing; CAO ChongDe; WEI BingBo


    The metastable liquid phase separation and rapid solidification of Cu60Fe30Co10 ternary peritectic alloy were investigated by using the drop tube technique and the differential scanning calorimetry method. It was found that the critical temperature of metastable liquid phase separation in this alloy is 1623.5 K, and the two separated liquid phases solidify as Cu(Fe,Co) and Fe(Cu,Co) solid solutions, respectively. The undercooling and cooling rate of droplets processed in the drop tube increase with the decrease of their diameters. During the drop tube processing, the structural morphologies of undercooled droplets are strongly dependent on the cooling rate. With the increase of the cooling rate, Fe(Cu,Co) spheres are refined greatly and become uniformly dispersed in the Cu-rich matrix. The calculations of Marangoni migration velocity (VM) and Stokes motion velocity (VS) of Fe(Cu,Co) droplets indicated that Marangoni migration contributes more to the coarsening and congregation of the minor phase during free fall. At the same undercooling, the VM/VS ratio increases drastically as Fe(Cu,Co) droplet size decreases. On the other hand, a larger undercooling tends to increase the VM/VS value for Fe(Cu,Co) droplets with the same size.

  1. Phase Separation of Silicon-Containing Polymer/Polystyrene Blends in Spin-Coated Films. (United States)

    Li, Yang; Hu, Kai; Han, Xiao; Yang, Qinyu; Xiong, Yifeng; Bai, Yuhang; Guo, Xu; Cui, Yushuang; Yuan, Changsheng; Ge, Haixiong; Chen, Yanfeng


    In this Article, two readily available polymers that contain silicon and have different surface tensions, polydimethylsiloxane (PDMS) and polyphenylsilsequioxane (PPSQ), were used to produce polymer blends with polystyrene (PS). Spin-coated thin films of the polymer blends were treated by O2 reactive-ion etching (RIE). The PS constituent was selectively removed by O2 RIE, whereas the silicon-containing phase remained because of the high etching resistance of silicon. This selective removal of PS substantially enhanced the contrast of the phase separation morphologies for better scanning electron microscope (SEM) and atomic force microscope (AFM) measurements. We investigated the effects of the silicon-containing constituents, polymer blend composition, concentration of the polymer blend solution, surface tension of the substrate, and the spin-coating speed on the ultimate morphologies of phase separation. The average domain size, ranging from 100 nm to 10 μm, was tuned through an interplay of these factors. In addition, the polymer blend film was formed on a pure organic layer, through which the aspect ratio of the phase separation morphologies was further amplified by a selective etching process. The formed nanostructures are compatible with existing nanofabrication techniques for pattern transfer onto substrates.

  2. Surface modification of polytetrafluoroethylene column for two-stationary phase separations by counter-current chromatography. (United States)

    Quan, Kai-jun; Huang, Xin-yi; Li, Xiao-ting; Wang, Gao-hong; Liu, Yan-juan; Duan, Wen-da; Di, Duo-long


    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.

  3. Facile synthesis of gradient mesoporous carbon monolith based on polymerization-induced phase separation (United States)

    Xu, Shunjian; Luo, Yufeng; Zhong, Wei; Xiao, Zonghu; Luo, Yongping; Ou, Hui; Zhao, Xing-Zhong


    In this paper, a gradient mesoporous carbon (GMC) monolith derived from the mixtures of phenolic resin (PF) and ethylene glycol (EG) was prepared by a facile route based on polymerization-induced phase separation under temperature gradient (TG). A graded biphasic structure of PF-rich and EG-rich phases was first formed in preform under a TG, and then the preform was pyrolyzed to obtain the GMC monolith. The TG is mainly induced by the thermal resistance of the preferential phase separation layer at high temperature region. The pore structure of the monolith changes gradually along the TG direction. When the TG varies from 58°C to 29°C, the pore size, apparent porosity and specific surface area of the monolith range respectively from 18 nm to 83 nm, from 32% to 39% and from 140.5 m2/g to 515.3 m2/g. The gradient porous structure of the monolith is inherited from that of the preform, which depends on phase separation under TG in the resin mixtures. The pyrolysis mainly brings about the contraction of the pore size and wall thickness as well as the transformation of polymerized PF into glassy carbon.

  4. Ion-exchange vs reversed-phase chromatography for separation and determination of basic psychotropic drugs. (United States)

    Petruczynik, Anna; Wróblewski, Karol; Deja, Michał; Waksmundzka-Hajnos, Monika


    Ion exchange chromatography, an alternative to reversed-phase (RP) chromatography, is described in this paper. We aimed to obtain optimal conditions for the separation of basic drugs because silica-based RP stationary phases show silanol effect and make the analysis of basic analytes hardly possible. The retention, separation selectivity, symmetry of peaks and system efficiency were examined in different eluent systems containing different types of buffers at acidic pH and with the addition of organic modifiers: methanol and acetonitrile. The obtained results reveal a large influence of the salt cation used for buffer preparation and the type of organic modifier on the retention behavior of the analytes. These results were also compared with those obtained on an XBridge C18 column. The obtained results demonstrated that SCX stationary phases can be successfully used as alternatives to C18 stationary phases in the separation of basic compounds. The most selective and efficient chromatographic systems were applied for the quantification of some psychotropic drugs in fortified human serum samples.

  5. Liquid-liquid phase separation in aerosol particles: Imaging at the Nanometer Scale

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, Rachel; Wang, Bingbing; Kelly, Stephen T.; Lundt, Nils; You, Yuan; Bertram, Allan K.; Leone, Stephen R.; Laskin, Alexander; Gilles, Mary K.


    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.

  6. Mathematical modeling of separated two-phase turbulent reactive flows using a filtered mass density function approach for large eddy simulation (United States)

    Carrara, Mark David


    The overall objective of this dissertation is the development of a modeling and simulation approach for turbulent two-phase chemically reacting flows. A new full velocity-scalar filtered mass density function (FMDF) formulation for large eddy simulation (LES) of a separated two-phase flow is developed. In this formulation several terms require modeling that include important conditionally averaged phase-coupling terms (PCT). To close the PCT a new derivation of the local instantaneous two-phase equations is presented and important identities are derived relating the PCT to surface averages. The formulation is then applied for two particle laden flow cases and solved using a full particle based Monte-Carlo numerical solution procedure. The first case is a temporally developing counter-current mixing layer dilutely seeded with evaporating water droplets. Validation studies reveal excellent agreement of the full particle method to previous hybrid FDF studies and direct numerical simulations for single-phase flows. One-way coupled simulations reveal that the overall dispersion is maximized with unity Stokes number droplets. Two-way coupled simulations reveal the advantages of two FDF approaches where the subgrid variation of droplet properties are explicitly taken into account. Comparisons of the fully-coupled FDF approach are compared to more approximate means of determining phase-coupling based on filtered properties and local and compounded global errors are assessed. The second case considered is the combustion aluminum particles. A new mechanistic model for the ignition and combustion of aluminum particulate is developed that accounts for unsteady heating, melting, heterogeneous surface reactions (HSR) and quasi-steady burning. Results of this model agree well with experimental data for overall burn rates and ignition times. Two-phase simulations of aluminum particulate seeded mixing layer reveal the variations in flame radius resulting in local extinguishment

  7. Phase separated anionic domains in ternary mixed lipid monolayers at the air-water interface. (United States)

    Maloney, K M; Grainger, D W


    A series of ternary mixed monolayers containing varying amounts of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and equimolar additions of 1-palmitoyl-2-hydroxy-sn-glycero-3-phosphocholine (LYSO-PC) and palmitic acid (PA) were studied at the air-water interface. These mixed monolayers were used to model phospholipid biomembrane interfaces resulting from phospholipase A2 (PLA2) hydrolysis. Recent work [D.W. Grainger A. Reichert, H. Ringsdorf and C. Salesse (1989) Biochim. Biophys. Acta. 1023, 365-379] has shown that PLA2 hydrolysis of pure phospholipid monolayers results in formation of large PLA2 domains at the air-water interface. These domains are proposed to result from PLA2 adsorption to phase separated regions in the hydrolyzed monolayer. To elucidate the phase behaviour in these monolayer systems, surface pressure-area isotherms were measured for the ternary mixtures on pure water and buffered subphases. Fluorescence microscopy at the air-water interface was used to image fluorescent probe-doped monolayer mixtures during isothermal compressions. A water-soluble cationic carbocyanine dye was used to probe the interfacial properties of the mixed monolayers. Isotherm data do not provide unambiguous evidence for either phase separation or ideal mixing of monolayer components. Fluorescence microscopy is more revealing, showing that lateral phase separation of microstructures containing palmitic acid occurred only when monolayer subphases contained Ca2+ ions at alkaline pH. At either low pH or on Ca(2+)-free subphases, phase separation was not observed.

  8. Crystal growth in a three-phase system: diffusion and liquid-liquid phase separation in lysozyme crystal growth. (United States)

    Heijna, M C R; van Enckevort, W J P; Vlieg, E


    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.

  9. Statistical thermodynamics of liquid-liquid phase separation in ternary systems during complex coacervation (United States)

    Pawar, Nisha; Bohidar, H. B.


    Liquid-liquid phase separation leading to complex coacervation in a ternary system (oppositely charged polyion and macroion in a solvent) is discussed within the framework of a statistical thermodynamics model. The polyion and the macroion in the ternary system interact to form soluble aggregates (complexes) in the solvent, which undergoes liquid-liquid phase separation. Four necessary conditions are shown to drive the phase separation: (i) (σ23)3r/Φ23c≥((64)/(9α2))(χ23Φ3)2 , (ii) r≥[(64(χ23Φ3)2)/(9α2σ233)]1/2 , (iii) χ23≥((2χ231-1))/(Φ23cΦ3) , and (iv) (σ23)2/I≥(8)/(3α)(2χ231-1) (where σ23 is the surface charge on the complex formed due to binding of the polyelectrolyte and macroion, Φ23c is the critical volume fraction of the complex, χ23 is the Flory interaction parameter between polyelectrolyte and macroion, χ231 is the same between solvent and the complex, Φ3 is the volume fraction of the macroions, I is the ionic strength of the solution, α is electrostatic interaction parameter and r is typically of the order of molecular weight of the polyions). It has been shown that coacervation always requires a hydrated medium. In the case of a colloidal macroion and polyelectrolyte coacervation, molecular weight of polyelectrolyte must satisfy the condition r≥103Da to exhibit liquid-liquid phase separation. This model has been successfully applied to study the coacervation phenomenon observed in aqueous Laponite (macroion)-gelatin (polyion) system where it was found that the coacervate volume fraction, δΦ23˜χ2312 (where δΦ23 is the volume fraction of coacervates formed during phase separation). The free energy and entropy of this process have been evaluated, and a free-energy landscape has been drawn for this system that maps the pathway leading to phase separation.

  10. Elucidating the Weak Protein-Protein Interaction Mechanisms behind the Liquid-Liquid Phase Separation of a mAb Solution by Different Types of Additives. (United States)

    Wu, Guoliang; Wang Co-First, Shujing; Tian, Zhou; Zhang, Ning; Sheng, Han; Dai, Weiguo; Qian, Feng


    Liquid-liquid phase separation (LLPS) has long been observed during the physical stability investigation of therapeutic protein formulations. The buffer conditions and the presence of various excipients are thought to play important roles in the formulation development of monoclonal antibodies (mAbs). In this study, the effects of several small-molecule excipients (histidine, alanine, glycine, sodium phosphate, sodium chloride, sorbitol and sucrose) with diverse physical-chemical properties on LLPS of a model IgG1 (JM2) solutions were investigated by multiple techniques, including UV-vis spectroscopy, circular dichroism, differential scanning calorimetry/fluorimetry, size exclusion chromatography and dynamic light scattering. The LLPS of JM2 was confirmed to be a thermodynamic equilibrium process with no structural changes or irreversible aggregation of proteins. Phase diagrams of various JM2 formulations were constructed, suggesting that the phase behavior of JM2 was dependent on the solution pH, ionic strength and the presence of other excipients such as glycine, alanine, sorbitol and sucrose. Furthermore, we demonstrated that for this mAb, the interaction parameter (kD) determined at low protein concentration appeared to be a good predictor for the occurrence of LLPS at high concentration. Copyright © 2017. Published by Elsevier B.V.

  11. Scalar φ4 field theory for active-particle phase separation (United States)

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


    Recent theories predict phase separation among orientationally disordered active particles whose propulsion speed decreases rapidly enough with density. Coarse-grained models of this process show time-reversal symmetry (detailed balance) to be restored for uniform states, but broken by gradient terms; hence, detailed-balance violation is strongly coupled to interfacial phenomena. To explore the subtle generic physics resulting from such coupling, we here introduce ‘Active Model B’. This is a scalar φ4 field theory (or phase-field model) that minimally violates detailed balance via a leading-order square-gradient term. We find that this additional term has modest effects on coarsening dynamics, but alters the static phase diagram by creating a jump in (thermodynamic) pressure across flat interfaces. Both results are surprising, since interfacial phenomena are always strongly implicated in coarsening dynamics but are, in detailed-balance systems, irrelevant for phase equilibria.

  12. Phase separation in mixtures of thermotropic liquid crystals and flexible polymers

    Institute of Scientific and Technical Information of China (English)

    张红东; 林志群; 严栋; 杨玉良


    The spinodal equation and the concentration-induced anisotropic-isotropic transition equation of the mixtures of thermotropic liquid crystals and flexible polymers have been studied by using the molecular field theory The calculations of the phase diagrams of this system show that,besides the isotropic classic spinodal curve,there ex ists an anisotropic spinodal curve which has not been reported in literature.These two spinodal curves can be linked up by the concentration-induced anisotropic-isotropic transition line.In the various phase regions,demixing may take place due to different phase separation mechanisms.The phase equilibrium curve cannot always join the.spinodal curve at a critical point.These results are considered very meaningful for the understanding of the special properties of liquid crystal/polymer composites and very useful for controlling the morphology and the performance of PDLC materials

  13. Blood plasma separation in a long two-phase plug flowing through disposable tubing. (United States)

    Sun, Meng; Khan, Zeina S; Vanapalli, Siva A


    We report a simple technique to separate plasma from blood in a flowing immiscible plug. We investigate the effect of various control parameters such as blood dilution, injection flow rate, observation time and fluid properties on plasma separation. We find that the technique works best for diluted blood samples at low plug velocities and long observation times. We postulate that the main mechanism responsible for efficient separation is the sedimentation of blood cells in the plug and their subsequent collection by the moving plug causing a significant accumulation of cells at the rear of the plug. We discuss the time scales determining the sedimentation, advection and collection of a blood cell in the immiscible plug and propose a phase diagram that is able to predict the operating space for effective plasma separation. We demonstrate that the technique allows for the extraction of more than 60% of the plasma by volume from 1 μL of diluted blood. We show the practical significance of this method by compartmentalizing the separated plasma into discrete microfluidic droplets and detecting cholesterol. This technique features low consumption of blood (nL-scale) and low shear rate (∼1 s(-1)). It is inexpensive, easy to use, and has the potential to be developed as an efficient point-of-care device for blood diagnostics in resource-poor environments. More advanced applications could also be envisioned by integrating our plasma separation method into existing microfluidic drop manipulation techniques.

  14. Development and validation of a stability-indicating reverse phase ultra performance liquid chromatographic method for the estimation of nebivolol impurities in active pharmaceutical ingredients and pharmaceutical formulation. (United States)

    Thummala, Veera Raghava Raju; Lanka, Mohana Krishna


    A sensitive, stability-indicating gradient reverse phase ultra performance liquid chromatographic method has been developed for the quantitative estimation of nebivolol impurities in active pharmaceutical ingredient (API) and pharmaceutical formulation. Efficient chromatographic separation was achieved on an Acquity BEH C18 column (100 mm x 2.1 mm, 1.7 μm) with mobile phase of a gradient mixture. The flow rate of the mobile phase was 0.18 mL/min with column temperature of 30 degrees C and detection wavelength of 281 nm. The relative response factor values of (R*)-2-( benzylamino)-1-((S*)-6-fluorochroman-2-yl) ethanol ((R x S*) NBV-), (R)-1-((R)-6-fluorochroman-2-yl)-2-((S)-2-((S)-6-fluoro-chroman-2-yl)-2-hydroxyethyl-amino) ethanol ((RRSS) NBV-3), 1-(chroman-2-yl)-2-(2-(6-fluorochroman-2-yl)-2-hydroxyethyl amino) ethanol (monodesfluoro impurity), (S)-1-((R)-6-fluorochroman-2-yl)-2-((R)-2 (S*)-6-fluoro-chroman-2-yl)-2-hydroxyethylamino) ethanol hydrochloride ((RSRS) NBV-3) and (R*)-1-((S*)-6-fluorochroman-2-yl)-2-((S*)-2-((S*)-6-fluoro-chroman-2-yl)-2-hydroxyethylamino) ethanol ((R* S* S* S*) NBV-2) were 0.65, 0.91, 0.68, 0.92 and 0.91 respectively. Nebivolol formulation sample was subjected to the stress conditions of acid, base, oxidative, hydrolytic, thermal, humidity and photolytic degradation. Nebivolol was found to degrade significantly under peroxide stress condition. The degradation products were well resolved from nebivolol and its impurities. The peak purity test results confirmed that the nebivolol peak was homogenous and pure in all stress samples and the mass balance was found to be more than 98%, thus proving the stability-indicating power of the method. The developed method was validated according to International Conference on Hormonization (ICH) guidelines with respect to specificity, linearity, limits of detection and quantification, accuracy, precision and robustness.

  15. New kind of phase separation in a CA traffic model with anticipation (United States)

    Lárraga, M. E.; del Río, J. A.; Schadschneider, A.


    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 phase separation 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 phase separation with a condensed phase in which particles move coherently with finite velocity coexisting with either a non-condensed (free-flow) phase or another condensed phase that is non-moving.

  16. Self-assembly in a polymer matrix and its impact on phase separation. (United States)

    Dudowicz, Jacek; Douglas, Jack F; Freed, Karl F


    Molecular self-assembly often occurs in the presence of long chain polymers, and we develop a theory to describe the competition between self-assembly and phase separation that generally occurs in these complex fluid mixtures. The theory includes a description of the particularly interesting situation where the associating "monomeric" species form high molecular mass polymeric structures and where the assembly process transforms the phase boundary from a form typical of a polymer solution to one that more resembles a polymer blend. We consider both self-assembly upon cooling and upon heating, but the van der Waals interactions are chosen so that phase separation occurs only upon cooling in the absence of association. Systems that associate upon heating prove to be particularly rich, and closed loop and ordinary (upper solution critical) phase boundaries are found to coexist over a wide range of interaction parameter values. Each critical temperature in the limit of a large polymerization index for the matrix polymers approaches its respective theta temperature. The calculations elucidate basic physical principles governing the phase behavior of these complex mixtures.

  17. Polymer Wall Formation Using Liquid-Crystal/Polymer Phase Separation Induced on Patterned Polyimide Films (United States)

    Murashige, Takeshi; Fujikake, Hideo; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio


    We could form lattice-shaped polymer walls in a liquid crystal (LC) layer through the thermal phase separation 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 phase separation. 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.

  18. Phase Separation in Bulk Heterojunctions of Semiconducting Polymers and Fullerenes for Photovoltaics (United States)

    Treat, Neil D.; Chabinyc, Michael L.


    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 phase-separated morphology that is formed during solution casting. This article reviews recent work to understand the nature of the phase-separation 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.

  19. Molecular dynamics study of phase separation in fluids with chemical reactions. (United States)

    Krishnan, Raishma; Puri, Sanjay


    We present results from the first d=3 molecular dynamics (MD) study of phase-separating 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 phase-separating 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.

  20. Magnetically induced nonvolatile magnetoresistance and resistance memory effect in phase-separated manganite thin films (United States)

    Li, Qian; Cao, Qingqi; Wang, Dunhui; Du, Youwei


    We report the observation of magnetically induced resistance memory effect in a typical electronic phase-separated 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 phase-separated manganite. The origin and potential applications of these interesting effects are discussed.

  1. Improving the performance of polymer solar cells by adjusting the crystallinity and nanoscale phase separation

    Institute of Scientific and Technical Information of China (English)

    Chen Wei-Bing; Xu Zong-Xiang; Li Kai; Chui Stephen Sin-Yin; Roy V.A.L.; Lai Pui-To; Che Chi-Ming


    In this paper,we report a high-performance P3HT/PCBM bulk-heterojunction solar cell with a power conversion efficiency of 4.85% fabricated by adjusting the polymer crystallinity and nanoscale phase separation using an ultrasonic irradiation mixing approach for the polymer.The grazing incidence X-ray diffraction,UV/Vis spectroscopic,and atomic force microscopic measurement results for the P3HT/PCBM blend films reveal that the P3HT/PCBM film fabricated by ultrasonic irradiation mixing of the P3HT and PCBM solutions for 10 min has a higher degree of cryetallinity,a higher absorption efficiency,and better phase separation,which together account for the higher charge transport properties and photovoltaic cell performance.

  2. Synthesis of semicrystalline nanocapsular structures obtained by Thermally Induced Phase Separation in nanoconfinement (United States)

    Torino, Enza; Aruta, Rosaria; Sibillano, Teresa; Giannini, Cinzia; Netti, Paolo A.


    Phase separation 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 Phase Separation (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.

  3. Separation of Quadruplex Polymorphism in DNA Sequences by Reversed-Phase Chromatography (United States)

    Miller, M. Clarke; Ohrenberg, Carl J.; Kuttan, Ashani; Trent, John O.


    This unit describes a method for the separation of a mixture of quadruplex conformations formed from the same parent sequence via reversed-phase 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-phase chromatography, has been a mainstay of nucleic acids research and purification for many decades. We have successfully applied this method to the problem of separating individual quadruplex species in the ensemble from the same parent sequence. PMID:26344226

  4. Separation of basic oligopeptides by ion-pairing reversed-phase chromatography (United States)

    Xie, Wenchun

    The present thesis consist of five chapters. Chapter I introduces background information on the ion-pairing reversed-phase chromatography and liquid chromatography in the critical condition. Chapter II decribes our study on the isocratic separation of oligolysine (dp = 2 to 8) using a fixed content of acetonitrile (ACN) (23%) and different concentrations of HFBA in the mobile phase (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 separated 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 phase. 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 phase 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

  5. Gas-phase simulated moving bed: Propane/propylene separation on 13X zeolite. (United States)

    Martins, Vanessa F D; Ribeiro, Ana M; Plaza, Marta G; Santos, João C; Loureiro, José M; Ferreira, Alexandre F P; Rodrigues, Alírio E


    In the last years several studies were carried out in order to separate gas mixtures by SMB technology; however, this technology has never been implemented on an industrial scale. In the present work, a gas phase SMB bench unit was built and tested for the separation of propane and propylene mixtures, using 13X zeolite extrudates as adsorbent and isobutane as desorbent. Three experiments were performed to separate propane/propylene by gas phase SMB in the bench scale unit with a 4-2-2 configuration, i.e., open loop circuit by suppressing section IV (desorbent regeneration followed by a recycle). Consequently, all the experiments were conducted using an external supply of pure isobutane as desorbent. Parameters such as switching time, extract and raffinate stream flow rates were changed to improve the efficiency of the process. Experimental results have shown that it is feasible to separate propylene from propane by gas phase SMB at a bench scale and that this process is a potential candidate to replace the conventional technologies for the propane/propylene separation. The performance parameters obtained are very promising for future development of this technology, since propylene was obtained in the extract stream with a purity of 99.93%, a recovery of 99.51%, and a productivity of [Formula: see text] . Propane was obtained in the raffinate stream with a purity of 98.10%, a recovery of 99.73% and a productivity of [Formula: see text] . The success of the above mentioned bench scale tests is a big step for the future implementation of this technology in a larger scale. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Vapor-phase elemental mercury adsorption by residual carbon separated from fly ash

    Institute of Scientific and Technical Information of China (English)

    WANG Li-gang; CHEN Chang-he; Kruse H.Kolker


    The adsorption capacity for vapor-phase elemental mercury(Hg0 ) of residual carbon separated from fly ash was studied in an attempt for the control of elemental mercury emissions from combustion processes. At Iow mercury concentrations ( < 200 μg/m3),unburned carbon had higher adsorption capacity than commercial activated carbon. The adsorbality of unburned carbon was also found to be source dependent. Isotherms of FS carbon(separated from fly ash of a power plant of Shishi in Fujian Province) were similar to those classified as type Ⅱ. Isotherms of XJ carbon (separated from fly ash of a power plant of Jingcheng in Shanxi Province) were more like those classified as type Ⅲ. Due to the relatively Iow production costs, these residual carbons would likely be considerably more costeffective for the full-scale removal of mercury from combustion flue gases than other technology.

  7. Separation of Recombinant β-Glucuronidase from Transgenic Tobacco by Aqueous Two-Phase Extraction



    Separation of Recombinant à -Glucuronidase from Transgenic Tobacco by Aqueous Two-Phase Extraction Kristin Coby Ross Abstract Biopharmaceutical manufacturing is a rigorous and expensive process. Due to the medicinal nature of the product, a high purity level is required and several expensive purification steps must be utilized. Cost-effective production and purification is essential for any biopharmaceutical product to be successful and development of the fastest, most economical, ...

  8. A mathematical model for phase separation: A generalized Cahn-Hilliard equation

    CERN Document Server

    Berti, Alessia; 10.1002/mma.1432


    In this paper we present a mathematical model to describe the phenomenon of phase separation, which is modelled as space regions where an order parameter changes smoothly. The model proposed, including thermal and mixing effects, is deduced for an incompressible fluid, so the resulting differential system couples a generalized Cahn-Hilliard equation with the Navier-Stokes equation. Its consistency with the second law of thermodynamics in the classical Clausius-Duhem form is finally proved.

  9. Three-dimensional simulations of phase separation in model binary alloy systems with elasticity

    Energy Technology Data Exchange (ETDEWEB)

    Orlikowski, D.; Roland, C. [North Carolina State Univ., Raleigh, NC (United States); Sagui, C. [McGill Univ., Montreal, Quebec (Canada). Dept. of Physics; Somoza, A.S. [Univ. de Murcia (Spain). Dept. de Fisica


    The authors report on large-scale three-dimensional simulations of phase separation in model binary alloy systems in the presence of elastic fields. The elastic field has several important effects on the morphology of the system: the ordered domains are subject to shape transformations, and spatial ordering. In contrast to two-dimensional system, no significant slowing down in the growth is observed. There is also no evidence of any reverse coarsening of the domains.

  10. Macrocyclic olefin metathesis at high concentrations by using a phase-separation strategy. (United States)

    Raymond, Michaël; Holtz-Mulholland, Michael; Collins, Shawn K


    Macrocyclic olefin metathesis has seen advances in the areas of stereochemistry, chemoselectivity, and catalyst stability, but strategies aimed at controlling dilution effects in macrocyclizations are rare. Herein, a protocol to promote macrocyclic olefin metathesis, one of the most common synthetic tools used to prepare macrocycles, at relatively high concentrations (up to 60 mM) is described by exploitation of a phase-separation strategy. A variety of macrocyclic skeletons could be prepared having either different alkyl, aryl, or amino acids spacers.

  11. Studies on the Recycling Efficiency of Thermoregulated Phase-separable Rh/PETPP Complex Catalyst

    Institute of Scientific and Technical Information of China (English)


    Effects on the recycling effieieney of thermoregulated phase-separable Rh/PETPP (P-[p-C6H4O(CH2CH2O)nH]3, N=3n) complex catalyst involved in hydroformylation of 1-decene are for the first time presented. It was found that the loss of Rh is dependent greatly on the composition of phosphine ligand PETPP and the organic solvent employed in the reaetion.

  12. Application of statistical design for the optimization of amino acid separation by reverse-phase HPLC. (United States)

    Gheshlaghi, R; Scharer, J M; Moo-Young, M; Douglas, P L


    Modified resolution and overall separation factors used to quantify the separation of complex chromatography systems are described. These factors were proven to be applicable to the optimization of amino acid resolution in reverse-phase (RP) HPLC chromatograms. To optimize precolumn derivatization with phenylisothiocyanate, a 2(5-1) fractional factorial design in triplicate was employed. The five independent variables for optimizing the overall separation factor were triethylamine content of the aqueous buffer, pH of the aqueous buffer, separation temperature, methanol/acetonitrile concentration ratio in the organic eluant, and mobile phase flow rate. Of these, triethylamine concentration and methanol/acetonitrile concentration ratio were the most important. The methodology captured the interaction between variables. Temperature appeared in the interaction terms; consequently, it was included in the hierarchic model. The preliminary model based on the factorial experiments was not able to explain the response curvature in the design space; therefore, a central composite design was used to provide a quadratic model. Constrained nonlinear programming was used for optimization purposes. The quadratic model predicted the optimal levels of the variables. In this study, the best levels of the five independent variables that provide the maximum modified resolution for each pair of consecutive amino acids appearing in the chromatograph were determined. These results are of utmost importance for accurate analysis of a subset of amino acids.

  13. Comparison of the performance of chiral stationary phase for separation of fluoxetine enantiomers

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jie; YANG Yi-wen; WEI Feng; WU Ping-dong


    Separation of fluoxetine enantiomers on five chiral stationary phases (chiralcel OD-H, chiralcel OJ-H, chiralpak AD-H, cyclobond I 2000 DM and kromasil CHI-TBB) was investigated. The optimal mobile phase compositions of fluoxetine separation on each column were hexane/isopropanol/diethyl amine (98/2/0.2, v/v/v), hexane/isopropanol/diethyl amine (99/1/0.1,v/v/v), hexane/isopropanol/diethyl amine (98/2/0.2, v/v/v), methanol/0.2% triethylamine acetic acid (TEAA) (25/75, v/v; pH 3.8)and hexane/isopropanol/diethyl amine (98/2/0.2, v/v/v), respectively. Experimental results demonstrated that baseline separation (RS>1.5) of fluoxetine enantiomers was obtained on chiralcel OD-H, chiralpak AD-H, and cyclobond I 2000 DM while the best separation was obtained on the last one. The eluate orders of fluoxetine enantiomers on the columns were determined. The first eluate by chiralcel OJ-H and kromasil CHI-TBB is the S-enantiomer, while by chiralpak AD-H and cyclobond I 2000 DM is the R-enantiomer.

  14. Utilization of a diol-stationary phase column in ion chromatographic separation of inorganic anions. (United States)

    Arai, Kaori; Mori, Masanobu; Kozaki, Daisuke; Nakatani, Nobutake; Itabashi, Hideyuki; Tanaka, Kazuhiko


    We describe the ion chromatographic separation of inorganic anions using a diol-stationary phase column (-CH(OH)CH(2)OH; diol-column) without charged functional groups. Anions were separated 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 phase column but smaller than that of an anion-exchange column. The separation 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 separation 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.

  15. Phase Separation Kinetics in Isopycnic Mixtures of H2O/CO2/Ethoxylated Alcohol Surfactants (United States)

    Lesemann, Markus; Paulaitis, Michael E.; Kaler, Eric W.


    Ternary mixtures of H2O and CO2 with ethoxylated alcohol (C(sub i)E(sub j)) surfactants form three coexisting liquid phases at conditions where two of the phases have equal densities (isopycnic phases). Isopycnic phase 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-phase 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 phase boundary and plait point are approached. In this report, we present our first measurements of the kinetics of isopycnic phase separation for ternary mixtures of H2O/CO2/C8E5.

  16. Effects of Particles Collision on Separating Gas–Particle Two-Phase Turbulent Flows

    KAUST Repository

    Sihao, L. V.


    A second-order moment two-phase turbulence model incorporating a particle temperature model based on the kinetic theory of granular flow is applied to investigate the effects of particles collision on separating gas–particle two-phase turbulent flows. In this model, the anisotropy of gas and solid phase two-phase Reynolds stresses and their correlation of velocity fluctuation are fully considered using a presented Reynolds stress model and the transport equation of two-phase stress correlation. Experimental measurements (Xu and Zhou in ASME-FED Summer Meeting, San Francisco, Paper FEDSM99-7909, 1999) are used to validate this model, source codes and prediction results. It showed that the particles collision leads to decrease in the intensity of gas and particle vortices and takes a larger effect on particle turbulent fluctuations. The time-averaged velocity, the fluctuation velocity of gas and particle phase considering particles colli-sion are in good agreement with experimental measurements. Particle kinetic energy is always smaller than gas phase due to energy dissipation from particle collision. Moreover, axial– axial and radial–radial fluctuation velocity correlations have stronger anisotropic behaviors. © King Fahd University of Petroleum and Minerals 2013

  17. Laser Phase Separation of Si Rich Oxides: The Role of Composition (United States)

    Sungur Ozen, Emel; Aydinli, Atilla; Gundogdu, Sinan


    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 phase separation. 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 phase separation. 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 phase separation.

  18. Photo polymerization-induced vertical phase separation and homeotropic alignment in liquid crystal and polymer mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Hyo [Samsung Advanced Institute of Technology, Yongin (Korea, Republic of); Joo, Sangwoo; Kang, Daeseung [Soongsil Univ., Seoul (Korea, Republic of)


    We presented a novel method for the homeotropic alignment of LC by using the irradiation of UV light on the LC/NOA65 mixture cell, in which the photo-initiated-polymerization-induced phase separation lowers the surface energy. When the amount of polymer content is sufficiently small, the gravel and network patterns were formed at the substrates via the vertical phase separation. We found that surface roughness plays an important role in the formation of the homeotropic alignment of LC. We also observed the alignment transition of the cells by varying the mixing ratio of LC/NOA65 or the UV radiation time. Furthermore, the present proposed method has great potential for application in display devices. For decades, studies on the alignment of liquid crystal (LC) molecules have been of significant interest due to their immediate applications for display devices and the intriguing physiochemical properties they exhibit at the surface of mixtures. Usually, homeotropic (or vertical) alignment, in which the long axes of the LC molecules are oriented in a direction perpendicular to the surface, is achieved by using surfactants such as lecithin, silanes or polyimide. Recently homeotropic alignment of liquid crystal molecules was achieved by irradiating photosensitive polymers, by doping nanoparticles into LC, by utilizing nano/micro patterns, or by incorporating self-assembled monolayers (SAMs). However, a clear understanding about the alignment mechanism is still elusive. In this paper, we report a novel method for homeotropic alignment of LC by utilizing the phase separation of LC/polymer mixtures.

  19. Influence of phase separation for surfactant driven pattern formation during ion beam erosion

    Energy Technology Data Exchange (ETDEWEB)

    Hofsaess, Hans; Zhang, Kun; Vetter, Ulrich; Bobes, Omar; Pape, Andre; Gehrke, Hans-Gregor; Broetzmann, Marc [II. Physikalisches Institut, Goettingen Univ. (Germany)


    We will present results on metal surfactant driven self-organized pattern formation on surfaces by ion beam erosion, with a focus on the role of phase separation for the initial steps of pattern formation. Si substrates were irradiated with 5 keV Xe ions at normal incidence and ion fluences up to 5.10{sup 17} Xe/cm{sup 2} under continuous deposition of surfactant atoms. In the absence of such surfactants uniform flat surfaces are obtained, while in the presence of Fe and Mo surfactants pronounced patterns like dots, combinations of dots and ripples with wavelengths around 100 nm are generated. The surfactant coverage and deposition direction determine the pattern type and the pattern orientation, respectively. A critical steady-state coverage for onset of dot formation and onset of ripple formation is in the range of 10{sup 15} and 5.10{sup 15} Xe/cm{sup 2}. The steady-state surface region consists of a thin amorphous metal silicide layer with high metal concentration in the ripple and dot regions. Pattern formation is explained by ion induced diffusion and phase separation of the initially flat amorphous silicide layer and subsequent ion beam erosion with composition dependent sputter yield. To investigate the role of initial phase separation we additionally compare the pattern formation for different other metal surfactants.


    Institute of Scientific and Technical Information of China (English)

    Fumihiko Tanaka; Tsuyoshi Koga; Hiroyuki Kojima; Francoise M. Winnik


    Collapse of a poly(N-isopropylacrylamide) (PNIPAM) chain upon heating and phase diagrams of aqueous PNIPAM solutions with very flat LCST phase separation line are theoretically studied on the basis of cooperative dehydration (simultaneous dissociation of bound water molecules in a group of correlated sequence), and compared with the experimental observation of temperature-induced coil-globule transition by light scattering methods. The transition becomes sharper with the cooperativity parameter σ of hydration. Reentrant coil-globule-coil transition in mixed solvent of water and methanol is also studied from the viewpoint of competitive hydrogen bonds between polymer-water and polymer-methanol. The downward shift of the cloud-point curves (LCST cononsolvency) with the mole fraction of methanol due to the competition is calculated and compared with the experimental data. Aqueous solutions of hydophobically-modified PNIPAM carrying short alkyl chains at both chain ends (telechelic PNIPAM) are theoretically and experimentally studied. The LCST of these solutions is found to shift downward along the sol-gel transition curve as a result of end-chain association (association-induced phase separation), and separate from the coil-globule transition line. Associated structures in the solution, such as flower micelles, mesoglobules and higher fractal assembly, are studied by USANS with theoretical modeling of the scattering function.

  1. Controlling Phase Separation of Tough Interpenetrating Polymer Networks via Addition of Amphiphilic Block Copolymers (United States)

    Rohde, Brian; Krishnamoorti, Ramanan; Robertson, Megan

    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 phase separation occurs and dictates the overall efficacy of combining mechanical properties. To control phase separation 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 phase separation 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.

  2. From molecular dehydration to excess volumes of phase-separating PNIPAM solutions. (United States)

    Philipp, Martine; Kyriakos, Konstantinos; Silvi, Luca; Lohstroh, Wiebke; Petry, Winfried; Krüger, Jan K; Papadakis, Christine M; Müller-Buschbaum, Peter


    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 phase separation. We elucidate the impact of partial dehydration of PNIPAM on the volume changes related to the phase separation 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 phase separation 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.

  3. Can visco-elastic phase separation, macromolecular crowding and colloidal physics explain nuclear organisation?

    Directory of Open Access Journals (Sweden)

    Iborra Francisco J


    Full Text Available Abstract Background The cell nucleus is highly compartmentalized with well-defined domains, it is not well understood how this nuclear order is maintained. Many scientists are fascinated by the different set of structures observed in the nucleus to attribute functions to them. In order to distinguish functional compartments from non-functional aggregates, I believe is important to investigate the biophysical nature of nuclear organisation. Results The various nuclear compartments can be divided broadly as chromatin or protein and/or RNA based, and they have very different dynamic properties. The chromatin compartment displays a slow, constrained diffusional motion. On the other hand, the protein/RNA compartment is very dynamic. Physical systems with dynamical asymmetry go to viscoelastic phase separation. This phase separation phenomenon leads to the formation of a long-lived interaction network of slow components (chromatin scattered within domains rich in fast components (protein/RNA. Moreover, the nucleus is packed with macromolecules in the order of 300 mg/ml. This high concentration of macromolecules produces volume exclusion effects that enhance attractive interactions between macromolecules, known as macromolecular crowding, which favours the formation of compartments. In this paper I hypothesise that nuclear compartmentalization can be explained by viscoelastic phase separation of the dynamically different nuclear components, in combination with macromolecular crowding and the properties of colloidal particles. Conclusion I demonstrate that nuclear structure can satisfy the predictions of this hypothesis. I discuss the functional implications of this phenomenon.

  4. Controlling Phase Separation of Interpenetrating Polymer Networks by Addition of Block Copolymers (United States)

    Rohde, Brian; Krishnamoorti, Ramanan; Robertson, Megan


    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 phase separated blend that exhibits poor mechanical behavior. To control phase separation 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 phase separation 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.

  5. Characteristics of phase transition and separation in a In-Ge-Sb-Te system

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Jin [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Jang, Moon Hyung [Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, PA 19104 (United States); Park, Seung-Jong [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Cho, Mann-Ho, E-mail: [Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749 (Korea, Republic of); Ko, Dae-Hong [Department of Material Science and Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)


    Highlights: Black-Right-Pointing-Pointer InGeSbTe films were fabricated via co-deposition stoichiometric GST and IST targets. Black-Right-Pointing-Pointer As the amount of IST was increased in InGeSbTe, the value for V{sub th} and the phase transition temperature were increased. Black-Right-Pointing-Pointer The phase separation in InGeSbTe is caused by differences in the enthalpy change for formation and different atomic concentrations. - Abstract: In-doped GeSbTe films were deposited by ion beam sputtering deposition (IBSD) using Ge{sub 2}Sb{sub 2}Te{sub 5} (GST) and In{sub 3}Sb{sub 1}Te{sub 2} (IST) as targets. The phase change characteristics of the resulting films were then investigated by electrical measurements, including static testing, in situ 4-point R{sub s} measurements, X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. The threshold voltage of the films increased, with increasing levels of IST. This phenomenon is consistent with the increased crystallization temperature in X-ray data and in situ 4-point R{sub s} data. In addition, in In{sub 28}Ge{sub 12}Sb{sub 26}Te{sub 34}, multiple V{sub th} values with a stepwise change are observed. The minimum time for the crystallization of InGeSbTe films was shorter than that for GST. X-ray data and Raman data for the crystalline structure show that phase separation to In{sub 2}Te{sub 3} occurred in all of the InGeSbTe samples after annealing at 350 Degree-Sign C. Moreover, in the case of InGeSbTe films with high concentrations of In (28 at.%), Sb phase separation was also observed. The observed phases indicate that the origin of the phase separation of InGeSbTe films is from the enthalpy change of formation and differences in Ge-Te, In-Te, Sb-Te, In-Sb and In-In bond energies.

  6. The K-Theoretic Formulation of D-Brane Aharonov-Bohm Phases

    Directory of Open Access Journals (Sweden)

    Aaron R. Warren


    Full Text Available The topological calculation of Aharonov-Bohm phases associated with D-branes in the absence of a Neveu-Schwarz B-field is explored. The K-theoretic classification of Ramond-Ramond fields in Type II and Type I theories is used to produce formulae for the Aharonov-Bohm phase associated with a torsion flux. A topological construction shows that K-theoretic pairings to calculate such phases exist and are well defined. An analytic perspective is then taken, obtaining a means for determining Aharonov-Bohm phases by way of the reduced eta-invariant. This perspective is used to calculate the phase for an experiment involving the (−1 −8 system in Type I theory and compared with previous calculations performed using different methods.


    Institute of Scientific and Technical Information of China (English)

    CHEN Jian-lei; HE Li-min; LUO Xiao-ming; BAI Hai-tao; WEI Yan-hai


    The combined T junctions used for the oil-water separation have the advantages of compactness in structure,consistency in effects and economy in cost.The mixture k-ε turbulence model and the Eulerian multi-fluid model are used to simulate the flow and phase distribution in the combined T junctions.The effects of structural parameters such as the branched pipe interval and height on the flow distribution and the separation behaviors are studied.The results show that the combined T junctions under fixed inlet and outlet boundary conditions form a single hydraulic equilibrium system in which the fluid energy distributes freely till a balance is achieved.The split-flow promotes the separation of the immiscible oil and the water.The separation efficiency increases with the increase of the branched pipe interval and changes slightly with the increase of the branched pipe height.The structural change of the combined T junctions may change the flow direction in the branched pipes.Simulation results can provide some guidance for the design of the combined T junctions as one kind of oil-water separator.

  8. Electronic phase separation at the LaAlO₃/SrTiO₃ interface. (United States)

    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


    There are many electronic and magnetic properties exhibited by complex oxides. Electronic phase separation (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 phases 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 separated into regions of a quasi-two-dimensional electron gas, a ferromagnetic phase, which persists above room temperature, and a (superconductor like) diamagnetic/paramagnetic phase 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.

  9. Phase separation and rapid solidification of liquid Cu60Fe30Co10 ternary peritectic alloy

    Institute of Scientific and Technical Information of China (English)


    The metastable liquid phase separation and rapid solidification of Cu60Fe30Co10 ternary peritectic alloy were investigated by using the drop tube technique and the differential scanning calorimetry method. It was found that the critical temperature of metastable liquid phase separation in this alloy is 1623.5 K, and the two sepa- rated liquid phases solidify as Cu(Fe,Co) and Fe(Cu,Co) solid solutions, respec- tively. The undercooling and cooling rate of droplets processed in the drop tube increase with the decrease of their diameters. During the drop tube processing, the structural morphologies of undercooled droplets are strongly dependent on the cooling rate. With the increase of the cooling rate, Fe(Cu,Co) spheres are refined greatly and become uniformly dispersed in the Cu-rich matrix. The calculations of Marangoni migration velocity (VM) and Stokes motion velocity (VS) of Fe(Cu,Co) droplets indicated that Marangoni migration contributes more to the coarsening and congregation of the minor phase during free fall. At the same undercooling, the VM/VS ratio increases drastically as Fe(Cu,Co) droplet size decreases. On the other hand, a larger undercooling tends to increase the VM/VS value for Fe(Cu,Co) drop- lets with the same size.

  10. Recent development in liquid chromatography stationary phases for separation of Traditional Chinese Medicine components. (United States)

    Jin, Hongli; Liu, Yanfang; Guo, Zhimou; Wang, Jixia; Zhang, Xiuli; Wang, Chaoran; Liang, Xinmiao


    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-phase liquid chromatography (RPLC) is still the method of choice for the separation 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 phases. This can improve the resolution and peak capacity considerably. In addition, high-efficiency stationary phases 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 phases. Their potential in the separation of TCMs using relevant applications is also demonstrated. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Nanoparticle Self-Assembly in a Polymer Matrix and Its Impact on Phase Separation (United States)

    Douglas, Jack


    The ubiquitous clustering of nanoparticles (NPs) in solutions and polymer melts depends sensitively on the strength and directionality of the effective NP-NP interactions, as well as on the molecular geometry and interactions of the dispersing fluid. Surface functionalization apparently can also lead to emergent anisotropic interactions that can influence NP dispersion. Since NP clustering can strongly influence the properties of polymer nanocomposites and NP solutions, we investigate the reversible self-assembly of model NPs into clusters under equilibrium conditions through a combination of simulation and analytic methods. First, we performed molecular dynamics simulations of polyhedral NPs in a coarse-grained dense bead--spring polymer melt and find a transition from a dispersed to clustered NP state, consistent with the thermodynamic models of equilibrium particle association such as equilibrium polymerization. We also describe the competition between self-assembly and phase separation in an analytic lattice model of a mixture of polymers and NPs. We then focus on the particularly interesting situation where the associating ``monomeric'' NP species form high molecular mass dynamic polymeric clusters and where the assembly process then transforms the phase boundary from a form typical of a polymer solution to one that more resembles a polymer blend with increasing association near the critical point for phase separation. The model calculations elucidate basic physical principles governing the coupling of self-assembly and phase behavior in these complex mixtures.

  12. Carrier-separating demodulation of phase shifting self-mixing interferometry (United States)

    Tao, Yufeng; Wang, Ming; Xia, Wei


    A carrier separating method associated with noise-elimination had been introduced into a sinusoidal phase-shifting self-mixing interferometer. The conventional sinusoidal phase 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 phase carrier with ultralow insertion loss in this paper. In order to extract phase-shift quickly and precisely, this paper employed the carrier-separating 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.

  13. Pressure-induced electronic phase separation of magnetism and superconductivity in CrAs. (United States)

    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


    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 superconducting and the magnetic volume fractions are spatially phase separated and compete for phase volume. Our results indicate that the less conductive magnetic phase 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 phase separation between magnetism and superconductivity point to a conventional mechanism of the Cooper-pairing in CrAs.

  14. Formulation of the twisted-light--matter interaction at the phase singularity: beams with strong magnetic fields

    CERN Document Server

    Quinteiro, G F; Kuhn, T


    The formulation of the interaction of matter with singular light fields needs special care. In a recent article [Phys.~Rev.~A {\\bf 91}, 033808 (2015)] we have shown that the Hamiltonian describing the interaction of a twisted light beam having parallel orbital and spin angular momenta with a small object located close to the phase singularity can be expressed only in terms of the electric field of the beam. Here, we complement our studies by providing an interaction Hamiltonian for beams having antiparallel orbital and spin angular momenta. Such beams may exhibit unusually strong magnetic effects. We further extend our formulation to radially and azimuthally polarized beams. The advantages of our formulation are that for all beams the Hamiltonian is written solely in terms of the electric and magnetic fields of the beam and as such it is manifestly gauge-invariant. Furthermore it is intuitive by resembling the well-known expressions in the dipole-electric and dipole-magnetic moment approximations.

  15. Gas-liquid phase separation in oppositely charged colloids: stability and interfacial tension. (United States)

    Fortini, Andrea; Hynninen, Antti-Pekka; Dijkstra, Marjolein


    We study the phase 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 phase transitions using free energy calculations and grand-canonical Monte Carlo simulations for varying inverse Debye screening length kappa. We find that the gas-liquid phase separation is stable for kappasigmaMonte 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.

  16. Thermomorphic phase separation in ionic liquid-organic liquid systems--conductivity and spectroscopic characterization. (United States)

    Riisager, Anders; Fehrmann, Rasmus; Berg, Rolf W; van Hal, Roy; Wasserscheid, Peter


    Electrical conductivity, FT-Raman and NMR measurements are demonstrated as useful tools to probe and determine phase 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 phase-separable system in the same temperature interval confirm the mutual solubility of the components in the system, the liquid-liquid equilibrium phase diagram of the binary mixture, and signify the importance of hydrogen bonding between the ionic liquid and the hydroxyl group of the alcohol.

  17. Phase Separation and Dynamics of two-component Bose-Einstein condensates

    CERN Document Server

    Lee, Kean Loon; Liu, I-Kang; Wacker, Lars; Arlt, Jan J; Proukakis, Nick P


    The miscibility of two interacting quantum systems is an important testing ground for the understanding of complex quantum systems. Two-component Bose-Einstein condensates enable the investigation of this scenario in a particularly well controlled setting. In a homogeneous system, the transition between mixed and separated phases is fully characterised by a `miscibility parameter', based on the ratio of intra- to inter-species interaction strengths. Here we show, however, that this parameter is no longer the optimal one for trapped gases, for which the location of the phase boundary depends critically on atom numbers. We demonstrate how monitoring of damping rates and frequencies of dipole oscillations enables the experimental mapping of the phase diagram by numerical implementation of a fully self-consistent finite-temperature kinetic theory for binary condensates. The change in damping rate is explained in terms of surface oscillation in the immiscible regime, and counterflow instability in the miscible reg...

  18. Phase Separation in the Heisenberg Spin System, Gd2Ti2O7 (United States)

    Gardner, J. S.; Stewart, J. R.; Ehlers, G.


    Gd2Ti2O7 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.

  19. Phase Separation in the Heisenberg Spin System Gd2Ti2O7

    Energy Technology Data Exchange (ETDEWEB)

    Ehlers, Georg [ORNL


    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.

  20. Phase II studies to select the formulation of a multivalent HPV L1 virus-like particle (VLP) vaccine. (United States)

    Luxembourg, Alain; Brown, Darron; Bouchard, Celine; Giuliano, Anna R; Iversen, Ole-Erik; Joura, Elmar A; Penny, Mary E; Restrepo, Jaime A; Romaguera, Josefina; Maansson, Roger; Moeller, Erin; Ritter, Michael; Chen, Joshua


    Our objective was to develop a multivalent prophylactic HPV vaccine that protects against infection and disease caused by HPV16/18 (oncogenic types in existing prophylactic vaccines) plus additional oncogenic types by conducting 3 Phase II studies comparing the immunogenicity (i.e., anti-HPV6/11/16/18 geometric mean titers [GMT]) and safety of 7 vaccine candidates with the licensed quadrivalent HPV6/11/16/18 vaccine (qHPV vaccine) in young women ages 16-26. In the first study (Study 1), subjects received one of 3 dose formulations of an 8-valent HPV6/11/16/18/31/45/52/58 vaccine or qHPV vaccine (control). In Study 2, subjects received one of 3 dose formulations (termed low-, mid-, and high-dose formulations, respectively) of a 9-valent HPV6/11/16/18/31/33/45/52/58 vaccine (9vHPV vaccine) or qHPV vaccine (control). In Study 3, subjects concomitantly received qHPV vaccine plus 5-valent HPV31/33/45/52/58 or qHPV vaccine plus placebo (control). All vaccines were administered at day 1/month 2/month 6. In studies 1 and 3, anti-HPV6/11/16/18 GMTs at month 7 were non-inferior in the experimental arms compared with the control arm; however, there was a trend for lower antibody responses for all 4 HPV types. In Study 2, this immune interference was overcome with the mid- and high-dose formulations of the 9vHPV vaccine by increasing antigen and adjuvant doses. In all 3 studies, all vaccine candidates were strongly immunogenic with respect to HPV31/33/45/52/58 and were well tolerated. Based on the totality of the results, the middle dose formulation of the 9vHPV vaccine was selected for Phase III evaluation. Each 0.5mL dose contains 30μg/40μg/60μg/40μg/20μg/20μg/20μg/20μg/20μg of HPV6/11/16/18/31/33/45/52/58 virus-like particles, and 500μg of amorphous aluminum hydroxyphosphate sulfate numbers NCT00260039, NCT00543543, and NCT00551187.

  1. Magnetic orderings and phase separations in a simple model of insulating systems (United States)

    Kapcia, Konrad Jerzy; Murawski, Szymon; Kłobus, Waldemar; Robaszkiewicz, Stanisław


    A simple effective model for a description of magnetically ordered narrow-band insulators is studied. The Hamiltonian considered consists of the effective on-site interaction (U) and intersite magnetic exchange interactions (Jz, Jxy) between nearest-neighbours. The phase diagrams and properties of this model for arbitrary chemical potential μ and arbitrary electron density n have been determined within several approaches: (i) the variational method (which treats the on-site interaction term exactly and the intersite interactions within the mean-field approximation) for any Jz,Jxy ≠ 0 (exact in the limit of infinite dimensions), (ii) the Monte Carlo simulations on a square lattice with periodic boundary conditions for Jxy = 0, and (iii) other approximate methods (inter alia: random phase approximation and spin-wave approximation) as well as (iv) rigorous treatment to obtain results concerning the ground state phase diagrams (the two last also for Jz,Jxy ≠ 0). The investigations of the general case show that, depending on the values of interaction parameters and electron concentration n, the system can exhibit not only homogeneous phases: (anti-)ferromagnetic (Fα, α = z, xy) and nonordered (NO), but also phase separated states (PSα: Fα/NO). For a fixed n one finds the following phase transitions (both continuous and discontinuous ones) and their sequences, which can occur with increasing temperature: Fα → NO, PSα → NO, PSα →Fα → NO, PSα →Fα →PSα → NO. The system analysed exhibits also tricritical behaviour.

  2. Microphase-Separated PE/PEO Thin Films Prepared by Plasma-Assisted Vapor Phase Deposition. (United States)

    Choukourov, Andrei; Gordeev, Ivan; Ponti, Jessica; Uboldi, Chiara; Melnichuk, Iurii; Vaidulych, Mykhailo; Kousal, Jaroslav; Nikitin, Daniil; Hanyková, Lenka; Krakovský, Ivan; Slavínská, Danka; Biederman, Hynek


    Immiscible polymer blends tend to undergo phase separation with the formation of nanoscale architecture which can be used in a variety of applications. Different wet-chemistry techniques already exist to fix the resultant polymeric structure in predictable manner. In this work, an all-dry and plasma-based strategy is proposed to fabricate thin films of microphase-separated polyolefin/polyether blends. This is achieved by directing (-CH2-)100 and (-CH2-CH2-O-)25 oligomer fluxes produced by vacuum thermal decomposition of poly(ethylene) and poly(ethylene oxide) onto silicon substrates through the zone of the glow discharge. The strategy enables mixing of thermodynamically incompatible macromolecules at the molecular level, whereas electron-impact-initiated radicals serve as cross-linkers to arrest the subsequent phase separation at the nanoscale. The mechanism of the phase separation as well as the morphology of the films is found to depend on the ratio between the oligomeric fluxes. For polyolefin-rich mixtures, polyether molecules self-organize by nucleation and growth into spherical domains with average height of 22 nm and average diameter of 170 nm. For equinumerous fluxes and for mixtures with the prevalence of polyethers, spinodal decomposition is detected that results in the formation of bicontinuous structures with the characteristic domain size and spacing ranging between 5 × 10(1) -7 × 10(1) nm and 3 × 10(2)-4 × 10(2) nm, respectively. The method is shown to produce films with tunable wettability and biologically nonfouling properties.

  3. Two-phase anaerobic digestion of vegetable market waste fraction of municipal solid waste and development of improved technology for phase separation in two-phase reactor. (United States)

    Majhi, Bijoy Kumar; Jash, Tushar


    Biogas production from vegetable market waste (VMW) fraction of municipal solid waste (MSW) by two-phase 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-phase anaerobic reactors was the techniques applied for solid-liquid phase separation of digestate in the first reactor where solubilization, hydrolysis and acidogenesis of solid organic waste occur. In this study, a two-phase reactor which consisted of a solid-phase 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-phase reactor to separate the process liquid produced in the first reactor. Experiments were carried out to assess the long term performance of the two-phase 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-phase reactors. The VS reduction was 82-86%. The two-phase anaerobic digestion system was demonstrated to be stable and suitable for the treatment of VMW fraction of MSW for energy generation.

  4. Managing Zirconium Chemistry and Phase Compatibility in Combined Process Separations for Minor Actinide Partitioning

    Energy Technology Data Exchange (ETDEWEB)

    Wall, Nathalie [Washington State Univ., Pullman, WA (United States); Nash, Ken [Washington State Univ., Pullman, WA (United States); Martin, Leigh [Washington State Univ., Pullman, WA (United States)


    In response to the NEUP Program Supporting Fuel Cycle R&D Separations and Waste Forms call DEFOA- 0000799, this report describes the results of an R&D project focusing on streamlining separation processes for advanced fuel cycles. An example of such a process relevant to the U.S. DOE FCR&D program would be one combining the functions of the TRUEX process for partitioning of lanthanides and minor actinides from PUREX(UREX) raffinates with that of the TALSPEAK process for separating transplutonium actinides from fission product lanthanides. A fully-developed PUREX(UREX)/TRUEX/TALSPEAK suite would generate actinides as product(s) for reuse (or transmutation) and fission products as waste. As standalone, consecutive unit-operations, TRUEX and TALSPEAK employ different extractant solutions (solvating (CMPO, octyl(phenyl)-N,Ndiisobutylcarbamoylmethylphosphine oxide) vs. cation exchanging (HDEHP, di-2(ethyl)hexylphosphoric acid) extractants), and distinct aqueous phases (2-4 M HNO3 vs. concentrated pH 3.5 carboxylic acid buffers containing actinide selective chelating agents). The separate processes may also operate with different phase transfer kinetic constraints. Experience teaches (and it has been demonstrated at the lab scale) that, with proper control, multiple process separation systems can operate successfully. However, it is also recognized that considerable economies of scale could be achieved if multiple operations could be merged into a single process based on a combined extractant solvent. The task of accountability of nuclear materials through the process(es) also becomes more robust with fewer steps, providing that the processes can be accurately modeled. Work is underway in the U.S. and Europe on developing several new options for combined processes (TRUSPEAK, ALSEP, SANEX, GANEX, ExAm are examples). There are unique challenges associated with the operation of such processes, some relating to organic phase chemistry, others arising from the

  5. Phase separation in polymer solutions. I. Liquid-liquid phase separation of PPO poly (2, 6-dimethyl 1, 4-phenylene oxide) in binary mixtures with toluene and ternary mixtures with toluene and ethyl alcohol

    NARCIS (Netherlands)

    Emmerik, van P.T.; Smolders, C.A.


    In the system poly(2, 6-dimethy1-1, 4-phenylene oxide) (PPO)-toluene three phase separation lines can be detected: the melting point curve, the cloud point curve, and the spinodial. Because crystallization of PPO occurs very slowly, a phase transition will always be initiated by liquid-liquid phase

  6. Phase separation in polymer solutions. I. Liquid-liquid phase separation of PPO poly (2, 6-dimethyl 1, 4-phenylene oxide) in binary mixtures with toluene and ternary mixtures with toluene and ethyl alcohol

    NARCIS (Netherlands)

    van Emmerik, P.T.; Smolders, C.A.


    In the system poly(2, 6-dimethy1-1, 4-phenylene oxide) (PPO)-toluene three phase separation lines can be detected: the melting point curve, the cloud point curve, and the spinodial. Because crystallization of PPO occurs very slowly, a phase transition will always be initiated by liquid-liquid phase

  7. Exoplanet albedo spectra and colors as a function of planet phase, separation, and metallicity

    CERN Document Server

    Cahoy, Kerri L; Fortney, Jonathan J


    First generation optical coronagraphic telescopes will obtain images of cool gas and ice giant exoplanets around nearby stars. The albedo spectra of exoplanets at planet-star separations larger than about 1 AU are dominated by reflected light to beyond 1 {\\mu}m and are punctuated by molecular absorption features. We consider how exoplanet albedo spectra and colors vary as a function of planet-star separation, metallicity, mass, and observed phase for Jupiter and Neptune analogs from 0.35 to 1 {\\mu}m. We model Jupiter analogs with 1x and 3x the solar abundance of heavy elements, and Neptune analogs with 10x and 30x. Our model planets orbit a solar analog parent star at separations of 0.8 AU, 2 AU, 5 AU, and 10 AU. We use a radiative-convective model to compute temperature-pressure profiles. The giant exoplanets are cloud-free at 0.8 AU, have H2O clouds at 2 AU, and have both NH3 and H2O clouds at 5 AU and 10 AU. For each model planet we compute moderate resolution spectra as a function of phase. The presence a...

  8. Separation of nucleation and growth of voids during tensile deformation of a dual phase steel using synchrotron microtomography

    Energy Technology Data Exchange (ETDEWEB)

    Requena, Guillermo, E-mail: [INSA-Lyon, MATEIS CNRS UMR5510, F-69621 Villeurbanne (France); Maire, Eric; Leguen, Claire [INSA-Lyon, MATEIS CNRS UMR5510, F-69621 Villeurbanne (France); Thuillier, Sandrine [LIMATB, Université de Bretagne-Sud, rue de Saint Maudé, BP 92116, 56321 Lorient Cedex (France)


    The damage evolution in a DP980 dual phase steel is followed in situ by synchrotron microtomography during tensile deformation focusing on the effect that the triaxiality, induced by different sample geometries, exerts on damage formation and damage evolution. The growth of existing voids is separated from the voids nucleated between consecutive deformation steps using three-dimensional image analysis. The experimental results are correlated with those obtained by finite element analysis using a Gurson–Tvergaard–Needleman framework with a Chu and Needleman formulation to introduce the effect of nucleation of cavities. A relatively simple way to determine the nucleation parameters is proposed based on the volume of nucleated voids obtained from the tomographies. The evolution of the total volume fraction of cavities obtained from the calculations shows a good agreement with the experiments for the notched samples and reflects the effect of triaxiality on damage. Contrarily to experiments, the calculated accumulated volume fraction of nucleated voids does not reflect the effect of triaxiality suggesting the necessity to implement this parameter in the nucleation model.

  9. Phase separation and exchange bias effect in Ca doped EuCrO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Dongmei, E-mail: [Department of Physics and Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Wang, Xingyu; Zheng, Jiashun; Qian, Xiaolong [Department of Physics and Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Yu, Dehong; Sun, Dehui [Bragg Institute, Australian Nuclear Science and Technology Organization, Kirrawee DC, NSW 2232 (Australia); Jing, Chao [Department of Physics and Materials Genome Institute, Shanghai University, Shanghai 200444 (China); Lu, Bo [Analysis and Measurement Center and Laboratory for Microstructures of Shanghai University, Shanghai 200444 (China); Kang, Baojuan; Cao, Shixun; Zhang, Jincang [Department of Physics and Materials Genome Institute, Shanghai University, Shanghai 200444 (China)


    The rare-earth chromites have attracted increasing interests in recent years, as a member of a few single-phase multiferroic materials. We studied the structure and magnetic property of a series of Ca-doped EuCrO{sub 3} samples by using X-ray powder diffraction and Physical Property Measurement System. Phase separation, rotation of magnetization in M(T) curve and exchange bias effect have been identified. The Eu{sub 0.7}Ca{sub 0.3}CrO{sub 3} polycrystalline sample may be intrinsically phase-separated, with Cr{sup 3+}-rich, Cr{sup 4+}-rich canted antiferromagnetic regions surrounded by spin glass-like frustrated phase, resulting in several magnetic features including: (1) a broad and slow increase of M(T) curve with the decrease of temperature; (2) rotation of magnetization with increasing cooling field; (3) exchange bias and glassy magnetism. The rotation of magnetization is ascribed to the rotation of the moment of Cr{sup 4+}-rich regions, arising from the competition between exchange coupling energy and magnetostatic energy. The exchange bias effect suggests the formation of weak ferromagnetic unidirectional anisotropy during field cooling, due to the exchange coupling among weak ferromagnetic domains and surrounding spin glass-like regions. This result helps understanding the interaction among different magnetic domains and phases in a complex system. - Highlights: • Exchange bias effect and glassy magnetism were observed in Eu{sub 0.7}Ca{sub 0.3}CrO{sub 3}. • Rotation of the moments of Cr{sup 4+}-rich regions result in the rotation of magnetization in M(T) curve. • Spin glass-like regions contribute to the observed exchange bias effect.

  10. Guidelines for the formulation of Lagrangian stochastic models for particle simulations of single-phase and dispersed two-phase turbulent flows

    Energy Technology Data Exchange (ETDEWEB)

    Minier, Jean-Pierre, E-mail: [EDF R and D, Mécanique des Fluides, Energie et Environnement, 6 quai Watier, 78400 Chatou (France); Chibbaro, Sergio [Sorbonne Universités, Institut Jean Le Rond d’Alembert, UPMC Univ Paris 06, CNRS, UMR7190, F-75005 Paris (France); Pope, Stephen B. [Sibley School of Mechanical and Aerospace Engineering, Cornell University, 254 Upson Hall, Ithaca, New York 14853 (United States)


    In this paper, we establish a set of criteria which are applied to discuss various formulations under which Lagrangian stochastic models can be found. These models are used for the simulation of fluid particles in single-phase turbulence as well as for the fluid seen by discrete particles in dispersed turbulent two-phase flows. The purpose of the present work is to provide guidelines, useful for experts and non-experts alike, which are shown to be helpful to clarify issues related to the form of Lagrangian stochastic models. A central issue is to put forward reliable requirements which must be met by Lagrangian stochastic models and a new element brought by the present analysis is to address the single- and two-phase flow situations from a unified point of view. For that purpose, we consider first the single-phase flow case and check whether models are fully consistent with the structure of the Reynolds-stress models. In the two-phase flow situation, coming up with clear-cut criteria is more difficult and the present choice is to require that the single-phase situation be well-retrieved in the fluid-limit case, elementary predictive abilities be respected and that some simple statistical features of homogeneous fluid turbulence be correctly reproduced. This analysis does not address the question of the relative predictive capacities of different models but concentrates on their formulation since advantages and disadvantages of different formulations are not always clear. Indeed, hidden in the changes from one structure to another are some possible pitfalls which can lead to flaws in the construction of practical models and to physically unsound numerical calculations. A first interest of the present approach is illustrated by considering some models proposed in the literature and by showing that these criteria help to assess whether these Lagrangian stochastic models can be regarded as acceptable descriptions. A second interest is to indicate how future

  11. Industrialization of technology of continuous liquid phase separation. Renzoku ekiso bunri gijutsu no kogyoka

    Energy Technology Data Exchange (ETDEWEB)

    Nakaishi, H. (JGC Corp., Tokyo (Japan))


    As one example of process technology industrialized in 1960s, a continuous process by liquid phase adsorption is introduced, that was developed by an American enterprise for petroleum refining. The background of development is described in details and elements for its success are explained as well as the impact. The motive for development was to separate n-paraffin from oil with molecular sieves in order to raise octane values of gasoline. However, the scene realized in industrialization was in the separation of n-paraffin from kerosene to get raw materials for synthetic detergents. Although literature on gas phase adsorption was well documented at that time, liquid adsorption that was an untrodden field was decided to be explored in consideration of problems involved in high temperature required for gas phase sdsorption. Taking theoretical validity of a moving bed system into consideration, a pseudo-moving bed system, wherein adsorption beds are still and the take-in/-out position of liquid moves with time lapse, was developed for the sake of limited mechanical strength of adsorbent (zeolite)and biased flow caused by moving layers. Use of mathematical models as probes for phenomena of chemical engineering and for analysis of process performance by computers contributed greatly to the success. 3 refs., 1 fig.

  12. Where the linearized Poisson-Boltzmann cell model fails: Spurious phase separation in charged colloidal suspensions (United States)

    Tamashiro, M. N.; Schiessel, H.


    The Poisson-Boltzmann (PB) spherical Wigner-Seitz cell model—introduced to theoretically describe suspensions of spherical charged colloidal particles—is investigated at the nonlinear and linearized levels. The linearization of the mean-field PB functional yields linearized Debye-Hückel-type equations agreeing asymptotically with the nonlinear PB results in the weak-coupling (high-temperature) limit. Both the canonical (fixed number of microions) as well as the semigrand-canonical (in contact with an infinite salt reservoir) cases are considered and discussed in a unified linearized framework. In disagreement with the exact nonlinear PB solution inside a Wigner-Seitz cell, the linearized theory predicts the occurrence of a thermodynamical instability with an associated phase separation of the homogeneous suspension into dilute (gas) and dense (liquid) phases, being thus a spurious result of the linearization. We show that these artifacts, although thermodynamically consistent with quadratic expansions of the nonlinear functional and osmotic pressure, may be traced back to the nonfulfillment of the underlying assumptions of the linearization. This raises questions about the reliability of the prediction of gas/liquid-like phase separation in deionized aqueous suspensions of charged colloids mediated by monovalent counterions obtained by linearized theories.

  13. Density functional theory of gas-liquid phase separation in dilute binary mixtures. (United States)

    Okamoto, Ryuichi; Onuki, Akira


    We examine statics and dynamics of phase-separated states of dilute binary mixtures using density functional theory. In our systems, the difference of the solvation chemical potential between liquid and gas [Formula: see text] (the Gibbs energy of transfer) is considerably larger than the thermal energy [Formula: see text] for each solute particle and the attractive interaction among the solute particles is weaker than that among the solvent particles. In these conditions, the saturated vapor pressure increases by [Formula: see text], where [Formula: see text] is the solute density added in liquid. For [Formula: see text], phase separation is induced at low solute densities in liquid and the new phase remains in gaseous states, even when the liquid pressure is outside the coexistence curve of the solvent. This explains the widely observed formation of stable nanobubbles in ambient water with a dissolved gas. We calculate the density and stress profiles across planar and spherical interfaces, where the surface tension decreases with increasing interfacial solute adsorption. We realize stable solute-rich bubbles with radius about 30 nm, which minimize the free energy functional. We then study dynamics around such a bubble after a decompression of the surrounding liquid, where the bubble undergoes a damped oscillation. In addition, we present some exact and approximate expressions for the surface tension and the interfacial stress tensor.

  14. Roles of Interleaflet Coupling and Hydrophobic Mismatch in Lipid Membrane Phase-Separation Kinetics (United States)


    Characterizing the nanoscale dynamic organization within lipid bilayer membranes is central to our understanding of cell membranes at a molecular level. We investigate phase separation and communication across leaflets in ternary lipid bilayers, including saturated lipids with between 12 and 20 carbons per tail. Coarse-grained molecular dynamics simulations reveal a novel two-step kinetics due to hydrophobic mismatch, in which the initial response of the apposed leaflets upon quenching is to increase local asymmetry (antiregistration), followed by dominance of symmetry (registration) as the bilayer equilibrates. Antiregistration can become thermodynamically preferred if domain size is restricted below ∼20 nm, with implications for the symmetry of rafts and nanoclusters in cell membranes, which have similar reported sizes. We relate our findings to theory derived from a semimicroscopic model in which the leaflets experience a “direct” area-dependent coupling, and an “indirect” coupling that arises from hydrophobic mismatch and is most important at domain boundaries. Registered phases differ in composition from antiregistered phases, consistent with a direct coupling between the leaflets. Increased hydrophobic mismatch purifies the phases, suggesting that it contributes to the molecule-level lipid immiscibility. Our results demonstrate an interplay of competing interleaflet couplings that affect phase compositions and kinetics, and lead to a length scale that can influence lateral and transverse bilayer organization within cells. PMID:27574865

  15. Anaerobic digestion from residue of industrial cassava industrialization with acidogenic and methanogenic physical separation phases. (United States)

    Paixão, M A; Tavares, C R; Bergamasco, R; Bonifácio, A L; Costa, R T


    A trial was carried out in a continuous regimen, using a completely stirred tank reactor, at acidogenic phase, and a hybrid reactor (upflow anaerobic sludge blanket + fixed bed) at methanogenic phase at room temperature. The residue to be treated came from a flour and cassava meal industry, and the reactors operated for 300 d with affluent chemical oxygen demand (COD) concentrations of 7500, 9000, 11,000, and 14,000 mg/L. The final results showed a biogas production with a content of 80% methane and an average reduction of COD and free cyanide of nearly 96 and 98%, respectively. The separation of phases selected bacterial groups. At acidogenic phase, a predominance of propionic, n-butyric, and n-valeric acids, as well as a biomass composed of 95% fermentative bacilli, which were responsible for a 90% reduction in free cyanide concentration, was observed. At methanogenic phase, a predominance of methanogenic bacteria that came only from the Methanothrix genus was observed. The bacteria were responsible for high levels of organic matter removal and methane production.

  16. Quantification of Gymnemagenin and β-Sitosterol in Marketed Herbal Formulation by Validated Normal Phase HPTLC Method

    Directory of Open Access Journals (Sweden)

    Sachin E. Potawale


    Full Text Available This research study describes development and validation of new, rapid, accurate, robust, and precise, high performance thin layer chromatographic (HPTLC method for concurrent quantitative determination of gymnemagenin and β-sitosterol in herbal formulation with densitometric detection. Chromatographic separation was achieved on Merck aluminum HPTLC plates precoated with silica gel 60 F254. The optimized solvent system consisted of toluene : ethyl acetate : methanol (6.5 : 2.5 : 1.4, v/v/v. Developed plates were derivatized with 5% sulphuric acid reagent followed by heating at 110°C for 4 min in a preheated oven and scanned at 423 nm in reflectance-absorbance mode. The retention factor for gymnemagenin and β-sitosterol was found to be 0.27±0.02 and 0.78±0.02, respectively. The proposed densitometric method was validated according to ICH Q2 (R1 guidelines. Results were found to be linear over a range of 100–1200 ng band−1 and 200–1200 ng band−1 for gymnemagenin and β-sitosterol, respectively. The percent content of gymnemagenin and β-sitosterol in the marketed polyherbal formulation was found to be 0.0405% and 0.1377%, respectively. The proposed HPTLC method can be used for quantification of gymnemagenin and β-sitosterol in marketed polyherbal formulation used in the study in quality-control laboratories.

  17. Dielectrophoretic gating and phase separation of particles for micro- and nano-fluidic biodetection applications (United States)

    James, Conrad


    Performance metrics for biological detection systems are significantly impacted by their ability to separate target analytes from background materials, a process that aids in the elimination of false positives. We report here several implementations of an electro-hydrodynamic technique for separating analytes in nanoliter sample volumes. This technique, AC dielectrophoresis (DEP) accompanied by field-induced phase transitions, includes electric field- and shear-induced phenomena to modify local concentrations of suspended particles. This non-optical separation technique relies upon intrinsic electric polarizability, and thus requires no time-consuming and costly labeling steps. We have demonstrated biological and non-biological particle separation, and both batch-mode and continuous flow configurations have been developed. The dielectrophoretic gating technique has been optimized to produce large electric field gradients(∇E^2˜10^20V^2/m^3) and we are currently applying this technique for particle chaperone preconcentration and nucleic acid purification. For the first application, we have achieved 100x preconcentration factors and high efficiency particle valving with no degradation in flowrate. This technique will prove useful for bead-based assay systems utilizing packed beds or high throughput flow cytometry. In the second application, we have preconcentrated dsDNA target molecules, and shown that preconcentration of false-positive inducing ssDNA reporter oligonucleotides is negligible. This method can be integrated on-chip, providing a significant advantage over conventional off-chip purification technologies such as centrifugation and precipitation. We will also present our results in traveling wave DEP, a technique which utilizes phase-quadrature signals to preconcentrate and transport particles without the use of hydrodynamic forces.

  18. A Novel Fluorescence Immunoassay System Based on pH-Sensitive Phase Separating Technique

    Institute of Scientific and Technical Information of China (English)

    林鹏; 郑洪; 杨黄浩; 李东辉; 许金钩


    In this paper, it was discovered that a novel pH-sensitive copolymer of N-isopropylacrylamide (NIP) and N-(3-dimethylaminopropyl)methacrylamide (DMAPM) could be gotten by polymerization. The phase transition pH (pHtr) of P(NIP-DMAPM) polymer was found to be 7.4 at 37℃. The polymer was precipitated out of water above a critical pH=7.4 and re-dissolved below pH----7.4. The characteristic of this polymer made it possible to carry out the immunochemical steps of an immunoassay in a true solution and then to quickly separate the resulting product from the reaction mixture. In a competitive fluorescence immunoassay, the standard rabbit IgG and rabbit IgG immobilized on P(NIP-DMAPM) first competitively reacted with the fluorescein isothiocyanate (FITC) labeled antibody, then the pH of solution was adjusted above the pHtr of polymer to precipitate the polymer-immune complex,and the polymer-immune complex precipitate was separated and re-dissolved by the adjustment of pH, finally the FITC-labeled antibody in the immune complex was quantified by fluorescence measurement. The calibration graph for rabbit IgG was linear over the range of 100-1000 ng/mL with a detection limit of 11 ng/mL. The method is rapid, sensitive and simple. Owing to neutral pHtr of P(NIP-DMAPM), the damage to antigen-antibody immune complex was greatly decreased in the course of separation. In addition, a sandwich enzyme-linked fluorescence immunoassay method for the determination of human IgG was also developed, showing that the pH-sensitive phase separating immunoassay could be performed in the competitive method as well as the sandwich method.

  19. Modelling of two-phase flow based on separation of the flow according to velocity

    Energy Technology Data Exchange (ETDEWEB)

    Narumo, T. [VTT Energy, Espoo (Finland). Nuclear Energy


    The thesis concentrates on the development work of a physical one-dimensional two-fluid model that is based on Separation of the Flow According to Velocity (SFAV). The conventional way to model one-dimensional two-phase flow is to derive conservation equations for mass, momentum and energy over the regions occupied by the phases. In the SFAV approach, the two-phase mixture is divided into two subflows, with as distinct average velocities as possible, and momentum conservation equations are derived over their domains. Mass and energy conservation are treated equally with the conventional model because they are distributed very accurately according to the phases, but momentum fluctuations follow better the flow velocity. Submodels for non-uniform transverse profile of velocity and density, slip between the phases within each subflow and turbulence between the subflows have been derived. The model system is hyperbolic in any sensible flow conditions over the whole range of void fraction. Thus, it can be solved with accurate numerical methods utilizing the characteristics. The characteristics agree well with the used experimental data on two-phase flow wave phenomena Furthermore, the characteristics of the SFAV model are as well in accordance with their physical counterparts as of the best virtual-mass models that are typically optimized for special flow regimes like bubbly flow. The SFAV model has proved to be applicable in describing two-phase flow physically correctly because both the dynamics and steady-state behaviour of the model has been considered and found to agree well with experimental data This makes the SFAV model especially suitable for the calculation of fast transients, taking place in versatile form e.g. in nuclear reactors. 45 refs. The thesis includes also five previous publications by author.

  20. pH and Salt Effects on the Associative Phase Separation of Oppositely Charged Polyelectrolytes

    Directory of Open Access Journals (Sweden)

    Prateek K. Jha


    Full Text Available The classical Voorn-Overbeek thermodynamic theory of complexation and phase separation of oppositely charged polyelectrolytes is generalized to account for the charge accessibility and hydrophobicity of polyions, size of salt ions, and pH variations. Theoretical predictions of the effects of pH and salt concentration are compared with published experimental data and experiments we performed, on systems containing poly(acrylic acid (PAA as the polyacid and poly(N,N-dimethylaminoethyl methacrylate (PDMAEMA or poly(diallyldimethyl ammonium chloride (PDADMAC as the polybase. In general, the critical salt concentration below which the mixture phase separates, increases with degree of ionization and with the hydrophobicity of polyelectrolytes. We find experimentally that as the pH is decreased below 7, and PAA monomers are neutralized, the critical salt concentration increases, while the reverse occurs when pH is raised above 7. We predict this asymmetry theoretically by introducing a large positive Flory parameter (= 0.75 for the interaction of neutral PAA monomers with water. This large positive Flory parameter is supported by molecular dynamics simulations, which show much weaker hydrogen bonding between neutral PAA and water than between charged PAA and water, while neutral and charged PDMAEMA show similar numbers of hydrogen bonds. This increased hydrophobicity of neutral PAA at reduced pH increases the tendency towards phase separation despite the reduction in charge interactions between the polyelectrolytes. Water content and volume of coacervate are found to be a strong function of the pH and salt concentration.

  1. Separation of transition and heavy metals using stationary phase gradients and thin layer chromatography. (United States)

    Stegall, Stacy L; Ashraf, Kayesh M; Moye, Julie R; Higgins, Daniel A; Collinson, Maryanne M


    Stationary phase gradients for chelation thin layer chromatography (TLC) have been investigated as a tool to separate a mixture of metal ions. The gradient stationary phases were prepared using controlled rate infusion (CRI) from precursors containing mono-, bi-, and tri-dentate ligands, specifically 3-aminopropyltriethoxysilane, N-[3-(trimethoxysilyl)propyl] ethylenediamine, and N-[3-(trimethoxysilyl)propyl] diethylenetriamine. The presence and the extent of gradient formation were confirmed using N1s X-ray photoelectron spectroscopy (XPS). XPS results showed that the degree of modification was dependent on the aminosilane precursor, its concentration, and the rate of infusion. The separation of four transition and heavy metals (Co(2+), Pb(2+), Cu(2+), and Fe(3+)) on gradient and uniformly modified plates was compared using a mobile phase containing a stronger chelating agent, ethylenediaminetetraacetic acid (EDTA). The retention of the metal ions was manipulated by varying the surface concentration of the chelating ligands. The order of retention on unmodified plates and on plates modified with a monodentate ligand was Fe(3+)>Cu(2+)∼Pb(2+)∼Co(2+), while the order of retention on plates modified with bi- and tri-dentate ligands was Fe(3+)>Cu(2+)>Pb(2+)∼Co(2+). Fe(3+) and Cu(2+) were much more sensitive to the concentration of chelating ligand on the surface (displaying lower Rf values with increasing ligand concentration) than Pb(2+) and Co(2+). Complete separation was achieved using a high concentration of the tridentate ligand coupled with a longer time for modification, yielding a retention order of Fe(3+)>Cu(2+)>Co(2+)>Pb(2+). Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Hydration, phase separation and nonlinear rheology of temperature-sensitive water-soluble polymers. (United States)

    Tanaka, Fumihiko; Koga, Tsuyoshi; Kaneda, Isamu; Winnik, Françoise M


    The collapse of a poly(N-isopropylacrylamide) (PNIPAM) chain upon heating and the phase diagrams of aqueous PNIPAM solutions with a very flat lower critical solution temperature (LCST) phase separation line are theoretically studied on the basis of cooperative dehydration (simultaneous dissociation of bound water molecules in a group of correlated sequence), and compared with the experimental observation of temperature-induced coil-globule transition by light scattering methods. The transition becomes sharper with the cooperativity parameter σ of hydration. The reentrant coil-globule-coil transition and cononsolvency in a mixed solvent of water and methanol are also studied from the viewpoint of competitive hydrogen bonds between polymer-water and polymer-methanol. The downward shift of the cloud-point curves (LCST cononsolvency) with the mol fraction of methanol due to the competition is calculated and compared with the experimental data. Aqueous solutions of hydrophobically modified PNIPAM carrying short alkyl chains at both chain ends (telechelic PNIPAM) are theoretically and experimentally studied. The LCST of these solutions is found to shift downward along the sol-gel transition curve as a result of end-chain association (association-induced phase separation), and separate from the coil-globule transition line. Associated structures in the solution, such as flower micelles, mesoglobules, and higher fractal assembly, are studied by ultra small-angle neutron scattering with theoretical modeling of the scattering function. Dynamic-mechanical modulus, nonlinear stationary viscosity, and stress build-up in start-up shear flows of the associated networks are studied on the basis of the affine and non-affine transient network theory. The molecular conditions for thickening, strain hardening, and stress overshoot are found in terms of the nonlinear amplitude A of the chain tension and the tension-dissociation coupling constant g.

  3. Mechanics of the Separating Surface for a Two-Phase Co-current Flow in a Porous Medium

    DEFF Research Database (Denmark)

    Shapiro, Alexander A.


    A mechanical description of an unsteady two-phase co-current flow in a porous medium is developed based on the analysis of the geometry and motion of the surface separating the two phases. It is demonstrated that the flow should be considered as essentially three-dimensional, even if the phase ve...

  4. Thermoregulated Phase-separable Ru3(CO)12/PETPP Complex Catalyst for Hydrogenation of Styrene

    Institute of Scientific and Technical Information of China (English)


    Thermoregulated phase-separable Ru3(CO)12/PETPP (PETPP=P[p-C6H4O (CH2CH2O)n H]3, n=6) complex catalyst was first applied in the hydrogenation of styrene. Under the conditions: P(H2)=2.0MPa, T=90(C, styrene could be completely transferred and the yield of ethylbenzene reached up to 99.5%. After simple decantation, the catalyst could be reused for ten times without decreasing in activity.

  5. Energy of formation for AgIn liquid binary alloys along the line of phase separation

    CERN Document Server

    Bhuiyan, G M; Ziauddin-Ahmed, A Z


    We have investigated the energy of formation for AgIn liquid binary alloys along the solid-liquid phase separation line. A microscopic theory based on the first order perturbation has been applied. The interionic interaction and a reference liquid are the fundamental components of the theory. These are described by a local pseudopotential and the hard sphere liquids, respectively. The results of calculations reveal a characteristic feature that the energy of formation becomes minimum at the equiatomic composition, and thus indicates maximal mix-ability at this concentration. The energy of formation at a particular thermodynamic state that is at T 1173 K predicts the experimental trends fairly well.

  6. Computer simulation of phase separation and ordering processes in low-dimensional systems

    DEFF Research Database (Denmark)

    Mouritsen, O.G.; Shah, P.J.; Vitting Andersen, J.


    properties, and a possible universal classification of the late-stage dynamics. Evidence from kinetic lattice model calculations using computer-simulation techniques is presented in favor of a universal description of the dynamics in terms of algebraic growth laws with exponents which only depend...... on the nature of the conservation laws in effect. Atomic and molecular overlayers on solid surfaces and weakly-coupled atomic layers of certain three-dimensional crystals constitute a particularly suitable class of systems for studying fundamental aspects of ordering dynamics and phase separation in two...

  7. Long-term stability of phase-separated Half-Heusler compounds


    Krez, Julia; Balke, Benjamin; Felser, Claudia; Hermes, Wilfried; Schwind, Markus


    Half-Heusler (HH) compounds have shown high Figure of merits up to 1.5. The key to these high thermoelectric efficiencies is an intrinsic phase separation, which occurs in multicomponent Half-Heusler compounds and leads to an significantly reduction of the thermal conductivity. For commercial applications, compatible n- and p-type materials are essential and their thermal stability under operating conditions, e.g. for an automotive up to 873 K, needs to be guaranteed. For the first time, the ...

  8. Preparation of n-tetradecane-containing microcapsules with different shell materials by phase separation method

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui [Department of Chemical Engineering, Tsinghua University, Beijing (China); Zhang, Yan; Zhang, Qingwu [Department of Chemical Engineering, China University of Mining and Technology, Beijing (China); Wang, Xin; Zhang, Yinping [Department of Building Science, Tsinghua University, Beijing (China)


    Microcapsules for thermal energy storage and heat-transfer enhancement have attracted great attention. Microencapsulation of n-tetradecane with different shell materials was carried out by phase separation method in this paper. Acrylonitrile-styrene copolymer (AS), acrylonitrile-styrene-butadiene copolymer (ABS) and polycarbonate (PC) were used as the shell materials. The structures, morphologies and the thermal capacities of the microcapsules were characterized using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). The ternary phase diagrams showed the potential encapsulation capabilities of the three shell materials. The effects of the shell/core ratio and the molecular weight of the shell material on the encapsulation efficiency and the thermal capacity of the microcapsules were also discussed. Microcapsules with melting enthalpy > 100 J/g, encapsulation efficiency 66-75%, particle size<1 {mu}m were obtained for all three shell materials. (author)

  9. Light Diffraction of Aligned Polymer Fibers Periodically Dispersed by Phase Separation of Liquid Crystal and Polymer (United States)

    Murashige, Takeshi; Fujikake, Hideo; Sato, Hiroto; Kikuchi, Hiroshi; Kurita, Taiichiro; Sato, Fumio


    We have confirmed light diffraction of aligned polymer fibers obtained by a phase separation of an anisotropic-phase solution of liquid crystal and polymer. He—Ne laser light passing through the polymer fibers was scattered in the axis vertical to the fibers, and had two peaks of light intensity symmetrical to the center of the transmitting laser spot. The two peaks were found to be caused by light diffraction due to the periodic polymer-fiber dispersion because the peaks corresponded to values calculated by intervals between the fibers. The periodical fiber networks are considered to be formed by anisotropic spinodal decomposition. This effect can be used to measure the dispersion order of the polymer fibers.

  10. Optical phase locking of two infrared CW lasers separated by 100 THz

    CERN Document Server

    Chiodo, Nicola; Hrabina, Jan; Lours, Michel; Chea, Erick; Acef, Ouali


    We report on phase-locking of two continuous wave infrared laser sources separated by 100 THz emitting around 1029 nm and 1544 nm respectively. Our approach uses three independent harmonic generation processes of the IR laser frequencies in periodically poled MgO: LiNbO3 crystals to generate second and third harmonic of that two IR sources. The beat note between the two independent green radiations generated around 515 nm is used to phase-lock one IR laser to the other, with tunable radio frequency offset. In this way, the whole setup operates as a mini frequency comb (MFC) emitting four intense optical radiations (1544 nm, 1029 nm, 772 nm and 515 nm), with output powers at least 3 orders of magnitude higher than the available power from each mode emitted by femtosecond lasers.

  11. From phase separation to long-range order in a system of interacting electrons (United States)

    Derzhko, Volodymyr; Jȩdrzejewski, Janusz


    We study a system composed of fermions (electrons), hopping on a square lattice, and of immobile particles (ions), that is described by the spinless Falicov-Kimball Hamiltonian augmented by a next-nearest-neighbor attractive interaction between the ions (a nearest-neighbor repulsive interaction between the ions can be included and does not alter the results). A part of the grand-canonical phase diagram of this system is constructed rigorously, when the coupling between the electrons and ions is much stronger than the hopping intensity of electrons. The obtained diagram implies that, at least for a few rational densities of particles, by increasing the hopping intensity the system can be driven from a state of phase separation to a state with a long-range order. This kind of transitions occurs also, when the hopping fermions are replaced by hopping hard-core bosons.

  12. High-performance ferroelectric memory based on phase-separated films of polymer blends

    KAUST Repository

    Khan, Mohammad A.


    High-performance polymer memory is fabricated using blends of ferroelectric poly(vinylidene-fluoride-trifluoroethylene) (P(VDF-TrFE)) and highly insulating poly(p-phenylene oxide) (PPO). The blend films spontaneously phase separate into amorphous PPO nanospheres embedded in a semicrystalline P(VDF-TrFE) matrix. Using low molecular weight PPO with high miscibility in a common solvent, i.e., methyl ethyl ketone, blend films are spin cast with extremely low roughness (Rrms ≈ 4.92 nm) and achieve nanoscale phase seperation (PPO domain size < 200 nm). These blend devices display highly improved ferroelectric and dielectric performance with low dielectric losses (<0.2 up to 1 MHz), enhanced thermal stability (up to ≈353 K), excellent fatigue endurance (80% retention after 106 cycles at 1 KHz) and high dielectric breakdown fields (≈360 MV/m). © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Aqueous phase separation as a possible route to compartmentalization of biological molecules. (United States)

    Keating, Christine D


    How could the incredible complexity of modern cells evolve from something simple enough to have appeared in a primordial soup? This enduring question has sparked the interest of researchers since Darwin first considered his theory of natural selection. Organic molecules, even potentially functional molecules including peptides and nucleotides, can be produced abiotically. Amphiphiles such as surfactants and lipids display remarkable self-assembly processes including the spontaneous formation of vesicles resembling the membranes of living cells. Nonetheless, numerous questions remain. Given the presumably dilute concentrations of macromolecules in the prebiotic pools where the earliest cells are thought to have appeared, how could the necessary components become concentrated and encapsulated within a semipermeable membrane? What would drive the further structural complexity that is a hallmark of modern living systems? The interior of modern cells is subdivided into microcompartments such as the nucleoid of bacteria or the organelles of eukaryotic cells. Even within what at first appears to be a single compartment, for example, the cytoplasm or nucleus, chemical composition is often nonuniform, containing gradients, macromolecular assemblies, and/or liquid droplets. What might the internal structure of intermediate evolutionary forms have looked like? The nonideal aqueous solution chemistry of macromolecules offers an attractive possible answer to these questions. Aqueous polymer solutions will form multiple coexisting thermodynamic phases under a variety of readily accessible conditions. In this Account, we describe aqueous phase separation as a model system for biological compartmentalization in both early and modern cells, with an emphasis on systems that have been encapsulated within a lipid bilayer. We begin with an introduction to aqueous phase separation and discuss how this phenomenon can lead to microcompartmentalization and could facilitate biopolymer

  14. Surface Confined Ionic Liquid-A New Stationary Phase for the Separation of Ephedrines in High-performance Liquid Chromatography

    Institute of Scientific and Technical Information of China (English)

    Shu Juan LIU; Feng ZHOU; Xiao Hua XIAO; Liang ZHAO; Xia LIU; Sheng Xiang JIANG


    In this article, a new and effective stationary phase based on ionic liquid modified silica is first reported and used for the separation of ephedrines in high-performance liquid chromatography (HPLC). The separation results indicate the high efficiency and reproducibility of the stationary phase. The electrostatic interaction, ion-exchange interaction between the solutes and the stationary phase are considered to attribute the effective separation. Moreover, the free silanols on the surface of the silica are effectively masked by the immobilized ionic liquid, a result of which is to decrease the non-specific absorption.

  15. Facet-controlled phase separation in supersaturated Au-Ni nanoparticles upon shape equilibration

    Energy Technology Data Exchange (ETDEWEB)

    Herz, A., E-mail:, E-mail:; Rossberg, D.; Hentschel, M.; Theska, F.; Wang, D., E-mail:, E-mail:; Schaaf, P. [Department of Materials for Electronics and Electrical Engineering, Institute of Materials Science and Engineering and Institute of Micro- and Nanotechnologies MacroNano, TU Ilmenau, D-98693 Ilmenau (Germany); Friák, M. [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, v.v.i., Žižkova 22, CZ-616 62 Brno (Czech Republic); Central European Institute of Technology, CEITEC MU, Masaryk University, Kamenice 5, CZ-625 00 Brno (Czech Republic); Holec, D. [Department of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, A-8700 Leoben (Austria); Šob, M. [Central European Institute of Technology, CEITEC MU, Masaryk University, Kamenice 5, CZ-625 00 Brno (Czech Republic); Institute of Physics of Materials, Academy of Sciences of the Czech Republic, v.v.i., Žižkova 22, CZ-616 62 Brno (Czech Republic); Department of Chemistry, Faculty of Science, Masaryk University, Kotlářská 2, CZ-611 37 Brno (Czech Republic); Schneeweiss, O. [Institute of Physics of Materials, Academy of Sciences of the Czech Republic, v.v.i., Žižkova 22, CZ-616 62 Brno (Czech Republic)


    Solid-state dewetting is used to fabricate supersaturated, submicron-sized Au-Ni solid solution particles out of thin Au/Ni bilayers by means of a rapid thermal annealing technique. Phase separation in such particles is studied with respect to their equilibrium crystal (or Wulff) shape by subsequent annealing at elevated temperature. It is found that (100) faceting planes of the equilibrated particles are enriched with Ni and (111) faces with Au. Both phases are considered by quantum-mechanical calculations in combination with an error-reduction scheme that was developed to compensate for a missing exchange-correlation potential that would reliably describe both Au and Ni. The observed phase configuration is then related to the minimization of strongly anisotropic elastic energies of Au- and Ni-rich phases and results in a rather unique nanoparticle composite state that is characterized by nearly uniform value of elastic response to epitaxial strains all over the faceted surface. The same conclusion is yielded also by evaluating bi-axial elastic moduli when employing interpolated experimental elastic constants. This work demonstrates a useful route for studying features of physical metallurgy at the mesoscale.

  16. Bound state, phase separation and superconductivity in presence of Rashba spin-orbit coupling (United States)

    Kapri, Priyadarshini; Basu, Saurabh


    We have investigated the phase diagram for the t - J model at low electronic densities in presence of Rashba spin-orbit coupling (RSOC). We have rigorously derived a bound state criterion which arises out of a competition between the kinetic energy of the electrons and the exchange coupling between them. Further, we have obtained that the phase diagram consists of three phases, namely, a gas of electrons, a gas of bound pairs, and a fully phase separated state. Subsequently an extension of the pairing scenario is done at finite densities by solving a BCS gap equation. Finite superconducting correlations are observed for J values much lower than that required for the formation of a single bound pair, thereby indicating that pairing in a many particle environment requires weaker interaction strengths than that in the dilute case. We have further obtained that the RSOC increases the transition temperature for a p-wave pairing state, while it diminishes the same for an s-wave pairing correlations.

  17. In situ observation of macroscopic phase separation in cobalt hexacyanoferrate film (United States)

    Takachi, Masamitsu; Moritomo, Yutaka


    Lithium-ion secondary batteries (LIBs) store electric energy via Li+ deintercalation from cathode materials. The Li+ deintercalation frequently drives a first-order phase transition of the cathode material as a result of the Li-ordering or Li-concentration effect and causes a phase separation (PS) into the Li-rich and Li-poor phases. Here, we performed an in situ microscopic investigation of the PS dynamics in thin films of cobalt hexacyanoferrate, LixCo[Fe(CN)6]0.9, against Li+ deintercalation. The thick film (d = 1.5 μm) shows a characteristic macroscopic PS of several tens of μm into the green (Li1.6Co[Fe(CN)6]0.9) and black (Li.6Co[Fe(CN)6]0.9) phases in the x range of 1.0 < x < 1.6. Reflecting the substrate strain, the thin film (d = 0.5 μm) shows no trace of the PS in the entire x region. Our observation suggests that the macroscopic PS plays a significant role in the charge/discharge dynamics of the cathode.

  18. Mapping Liquid-liquid protein phase separation using ultra-fast-scanning fluorescence correlation spectroscopy (United States)

    Wei, Ming-Tzo; Elbaum-Garfinkle, Shana; Arnold, Craig B.; Priestley, Rodney D.; Brangwynne, Clifford P.

    Intrinsically disordered proteins (IDPs) are an understudied class of proteins that play important roles in a wide variety of biological processes in cells. We've previously shown that the C. elegans IDP LAF-1 phase separates into P granule-like droplets in vitro. However, the physics of the condensed phase remains poorly understood. Here, we use a novel technique, ultra-fast-scanning fluorescence correlation spectroscopy, to study the nano-scale rheological properties of LAF-1 droplets. Ultra-fast-scanning FCS uses a tunable acoustic gradient index of refraction (TAG) lens with an oil immersion objective to control axial movement of the focal point over a length of several micrometers at frequencies of 70kHz. Using ultra-fast-scanning FCS allows for the accurate determination of molecular concentrations and their diffusion coefficient, when the particle is passing through an excitation volume. Our work reveals an asymmetric LAF-1 phase diagram, and demonstrates that LAF-1 droplets are purely viscous phases which are highly tunable by salt concentration.

  19. Thermomorphic phase separation in ionic liquid-organic liquid systems - conductivity and spectroscopic characterization

    DEFF Research Database (Denmark)

    Riisager, Anders; Fehrmann, Rasmus; Berg, Rolf W.


    Electrical conductivity, FT-Raman and NMR measurements are demonstrated as useful tools to probe and determine phase behavior of thermomorphic ionic liquid-organic liquid systems. To illustrate the methods, consecutive conductivity measurements of a thermomorphic methoxyethoxyethyl-imidazolium io...... of the components in the system, the liquid-liquid equilibrium phase diagram of the binary mixture, and signify the importance of hydrogen bonding between the ionic liquid and the hydroxyl group of the alcohol.......Electrical conductivity, FT-Raman and NMR measurements are demonstrated as useful tools to probe and determine phase 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 H-1-NMR spectroscopic studies performed on the phase-separable system in the same temperature interval confirm the mutual solubility...

  20. Cubic phase nanoparticles for sustained release of ibuprofen formulation characterization and enhanced bioavailability study

    Directory of Open Access Journals (Sweden)

    Dian L


    Full Text Available Linghui Dian,1,2,* Zhiwen Yang,3,* Feng Li,1 Zhouhua Wang,1 Xin Pan,1 Xinsheng Peng,2 Xintian Huang,1 Zhefei Guo,1 Guilan Quan,1 Xuan Shi,1 Bao Chen,1 Ge Li,4 Chuanbin Wu1,41School of Pharmaceutical Sciences, Sun Yat-Sen University, University Town, Guangzhou, People’s Republic of China; 2School of Pharmaceutical Sciences, Guangdong Medical College, Dongguan, People’s Republic of China; 3Department of Gastroenterology, Songjiang Branch of the Affiliated First People’s Hospital of Shanghai Jiaotong University, Shanghai, People’s Republic of China; 4Guangdong Research Center for Drug Delivery Systems, Guangzhou, People’s Republic of China*These authors contributed equally to this workAbstract: In order to improve the oral bioavailability of ibuprofen, ibuprofen-loaded cubic nanoparticles were prepared as a delivery system for aqueous formulations. The cubic inner structure was verified by cryogenic transmission electron microscopy. With an encapsulation efficiency greater than 85%, the ibuprofen-loaded cubic nanoparticles had a narrow size distribution around a mean size of 238 nm. Differential scanning calorimetry and X-ray diffraction determined that ibuprofen was in an amorphous and molecular form within the lipid matrix. The in vitro release of ibuprofen from cubic nanoparticles was greater than 80% at 24 hours, showing sustained characteristics. The pharmacokinetic study in beagle dogs showed improved absorption of ibuprofen from cubic nanoparticles compared to that of pure ibuprofen, with evidence of a longer half-life and a relative oral bioavailability of 222% (P < 0.05. The ibuprofen-loaded cubic nanoparticles provide a promising carrier candidate with an efficient drug delivery for therapeutic treatment.Keywords: ibuprofen, cubic nanoparticles, oral drug delivery, bioavailability

  1. Phase I study of weekly DN-101, a new formulation of calcitriol, in patients with cancer. (United States)

    Beer, Tomasz M; Javle, Milind M; Ryan, Christopher W; Garzotto, Mark; Lam, Gilbert N; Wong, Alvin; Henner, W David; Johnson, Candace S; Trump, Donald L


    DN-101 is a new, high-dose, oral formulation of calcitriol under investigation for the treatment of cancer. We sought to evaluate the tolerability and pharmacokinetics (PK) of weekly doses of DN-101 in patients with advanced cancer. Patients who completed a previously reported single dose escalation study of DN-101 [Beer et al. (2005) Clin Cancer Res 11:7794-7799] were eligible for this continuation weekly dosing study. Cohorts of 3-10 patients were treated at doses of 15, 30, 45, 60, and 75 microg calcitriol. Once 45 microg was established as the maximum tolerated dose (MTD), this cohort was expanded to include 18 patients. Dose limiting toxicity (DLT) was defined as > or =grade 2 hypercalcemia or > or =grade 3 persistent treatment-related toxicities. Thirty-seven patients were recruited. DLT of transient reversible grade 2 hypercalcemia (serum calcium of 11.6-12.5 mg/dL) occurred in two of six patients treated with 60 microg of DN-101. No DLT was observed in the 18 patients who received DN-101 weekly at 45 microg. Overall, DN-101 was well tolerated. The most frequent adverse events were fatigue (27%), hypercalcemia (19%, including five grade 1, two grade 2, and no grade 3 or 4 events), and grade 1 nausea (16%). PK parameters following repeat dosing were comparable to those for the initial dose (n = 4). The MTD for weekly DN-101 was established as 45 mug. The DLTs observed were two episodes of rapidly reversible grade 2 hypercalcemia in two of the six patients treated at 60 microg weekly. Repeat doses of DN-101 at 45 microg weekly are well tolerated and this dose is suitable for studies of weekly DN-101 in cancer patients.

  2. Solubility and phase separation of benzocaine and salicylic acid in 1,4-dioxane-water mixtures at several temperatures. (United States)

    Peña, M Angeles; Bustamante, Pilar; Escalera, Begoña; Reíllo, Aurora; Bosque-Sendra, Juan Manuel


    The solubilities of benzocaine and salicylic acid were determined in water-dioxane mixtures at several temperatures (5-40 degrees C for benzocaine and 10-40 degrees C for salicylic acid). The solubility curves as a function of dioxane ratio showed a maximum at 90% dioxane at all temperatures. Above 25 degrees C, the homogeneous mixture splits into two liquid immiscible phases. For benzocaine, the initial dioxane concentration range at which phase separation takes place increased with temperature (50-60% at 25 degrees C, 50-70% at 30-35 degrees C and 40-70% at 40 degrees C). For salicylic acid, the dioxane concentration required for phase separation (40-60% dioxane) did not change with temperature. Phase separation was not related to solid phase changes (polymorphism or solvates). The phase composition and drug extraction at the drug-rich phase were determined. The apparent enthalpies of the solution process were a nonlinear function of the dioxane ratio for both drugs. The apparent enthalpy of solution of benzocaine was larger than that expected at the upper limit of phase separation (70% dioxane), whereas for salicylic acid the apparent enthalpy of solution decreased abruptly at the region corresponding to phase separation (40-70% dioxane). Both drugs showed a nonlinear pattern of enthalpy-entropy compensation.

  3. Simulation of phase separation with large component ratio for oil-in-water emulsion in ultrasound field. (United States)

    Wang, Heping; Li, Xiaoguang; Li, Yanggui; Geng, Xingguo


    This paper presents an exploration for separation of oil-in-water and coalescence of oil droplets in ultrasound field via lattice Boltzmann method. Simulations were conducted by the ultrasound traveling and standing waves to enhance oil separation and trap oil droplets. The focus was to the effect of ultrasound irradiation on oil-in-water emulsion properties in the standing wave field, such as oil drop radius, morphology and growth kinetics of phase separation. Ultrasound fields were applied to irradiate the oil-in-water emulsion for getting flocculation of the oil droplets in 420kHz case, and larger dispersed oil droplets and continuous phases in 2MHz and 10MHz cases, respectively. The separated phases started to rise along the direction of sound propagation after several periods. The rising rate of the flocks was significantly greater in ultrasound case than that of oil droplets in the original emulsion, indicating that ultrasound irradiation caused a rapid increase of oil droplet quantity in the progress of the separation. The separation degree was also significantly improved with increasing frequency or irradiation time. The dataset was rearranged for growth kinetics of ultrasonic phase separation in a plot by spherically averaged structure factor and the ratio of oil and emulsion phases. The analyses recovered the two different temporal regimes: the spinodal decomposition and domain growth stages, which further quantified the morphology results. These numerical results provide guidance for setting the optimum condition for the separation of oil-in-water emulsion in the ultrasound field.

  4. Factors influencing the separation of oligonucleotides using reversed-phase/ion-exchange mixed-mode high performance liquid chromatography columns. (United States)

    Biba, Mirlinda; Jiang, Eileen; Mao, Bing; Zewge, Daniel; Foley, Joe P; Welch, Christopher J


    New mixed-mode columns consisting of reversed-phase and ion-exchange separation modes were evaluated for the analysis of short RNA oligonucleotides (∼20mers). Conventional analysis for these samples typically involves using two complementary methods: strong anion-exchange liquid chromatography (SAX-LC) for separation based on charge, and ion-pair reversed-phase liquid chromatography (IP-RPLC) for separation based on hydrophobicity. Recently introduced mixed-mode high performance liquid chromatography (HPLC) columns combine both reversed-phase and ion-exchange modes, potentially offering a simpler analysis by combining the benefits of both separation modes into a single method. Analysis of a variety of RNA oligonucleotide samples using three different mixed-mode stationary phases showed some distinct benefits for oligonucleotide separation and analysis. When using these mixed-mode columns with typical IP-RPLC mobile phase conditions, such as ammonium acetate or triethylammonium acetate as the primary ion-pair reagent, the separation was mainly based on the IP-RPLC mode. However, when changing the mobile phase conditions to those more typical for SAX-LC, such as salt gradients with NaCl or NaBr, very different separation patterns were observed due to mixed-mode interactions. In addition, the Scherzo SW-C18 and SM-C18 columns with sodium chloride or sodium bromide salt gradients also showed significant improvements in peak shape.

  5. High-transparency, self-standable gel-SLIPS fabricated by a facile nanoscale phase separation. (United States)

    Okada, Issei; Shiratori, Seimei


    Slippery liquid-infused porous surfaces (SLIPSs) that were both highly transparent and free-standing (self-standability) were fabricated by an extremely simple process using non-solvent-induced phase separation (NIPS) of a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP)/di-n-butyl phthalate solution. We call these "Gel-SLIPS" because the porous PVDF-HFP film fabricated using the NIPS process has been used as a gel electrolyte in a lithium-ion battery. In previous reports, SLIPS fabrication required complex processes, high annealing temperatures, and drying. Gel-SLIPS can be fabricated from the adjusted solution and the lubricant at room temperature and pressure in 5 min by squeegee, cast, or dip methods. NIPS is based on a quick phase separation process in situ, and reduction of the surface energy is not required because of the considerable fluorine in PVDF-HFP. Moreover, because of the flexible nanonetwork structure of PVDF-HFP, Gel-SLIPS exhibited self-standability and high transmittance (>87% at 600 nm). Gel-SLIPS is thus highly versatile in terms of the fabrication process and film characteristics.

  6. Slaughterhouse wastewater treatment: evaluation of a new three-phase separation system in a UASB reactor. (United States)

    Caixeta, Cláudia E T; Cammarota, Magali C; Xavier, Alcina M F


    The anaerobic treatment of the wastewater from the meat processing industry was studied using a 7.2 1 UASB reactor. The reactor was equipped with an unconventional configuration of the three-phase separation system. The effluent was characterized in terms of pH (6.3-6.6), chemical oxygen demand (COD) (2,000-6,000 mg l(-1)), biochemical oxygen demand BOD5 (1,300-2,300 mg 1(-1)), fats (40-600 mg l(-1)) and total suspended solids (TSS) (850-6,300 mg l(-1)) The reactor operated continuously throughout 80 days with hydraulic retention time of 14, 18 and 22 h. The wastewater from Rezende Industrial was collected after it had gone through pretreatment (screening, flotation and equalization). COD, BOD and TSS reductions and the biogas production rate were the parameters considered in analyzing the efficiency of the process. The average production of biogas was 111 day(-1) (STP) for the three experimental runs. COD removal varied from 77% to 91% while BOD removal was 95%. The removal of total suspended solids varied from 81% to 86%. This fact supports optimal efficiency of the proposed three-phase separation system as well as the possibility of applying it to the treatment of industrial effluents.

  7. A novel bio-safe phase separation process for preparing open-pore biodegradable polycaprolactone microparticles. (United States)

    Salerno, Aurelio; Domingo, Concepción


    Open-pore biodegradable microparticles are object of considerable interest for biomedical applications, particularly as cell and drug delivery carriers in tissue engineering and health care treatments. Furthermore, the engineering of microparticles with well definite size distribution and pore architecture by bio-safe fabrication routes is crucial to avoid the use of toxic compounds potentially harmful to cells and biological tissues. To achieve this important issue, in the present study a straightforward and bio-safe approach for fabricating porous biodegradable microparticles with controlled morphological and structural features down to the nanometer scale is developed. In particular, ethyl lactate is used as a non-toxic solvent for polycaprolactone particles fabrication via a thermal induced phase separation technique. The used approach allows achieving open-pore particles with mean particle size in the 150-250 μm range and a 3.5-7.9 m(2)/g specific surface area. Finally, the combination of thermal induced phase separation and porogen leaching techniques is employed for the first time to obtain multi-scaled porous microparticles with large external and internal pore sizes and potential improved characteristics for cell culture and tissue engineering. Samples were characterized to assess their thermal properties, morphology and crystalline structure features and textural properties.

  8. Low-density, polymer foams as structural models for phase-separation in polymer solutions

    Energy Technology Data Exchange (ETDEWEB)

    Beaucage, G. [Univ. of Cincinnati, OH (United States); Lagasse, R.R.; Aubert, J.H. [Sandia National Labs., Albuquerque, NM (United States)] [and others


    Low density polymer foams are produced through nano-scale phase separation of 5 to 15% solutions yielding gels. The gels are solvent exchanged and dried by supercritical extraction. We have found that the morphology of the phase separated gel, the intermediate solvent exchanged gels and the final foams are essentially identical over a wide range of size. Through the combination of several scattering techniques covering many decades of size we can distinguish structural levels in these low-density foams. The combined scattering data spans sizes ranging from 10{mu}m to 1{Angstrom}. A recently developed global fitting approach can describe the multiple levels of structure observed in these complex materials. Several morphological classes of foams are observed. A perplexing feature in the scattering patterns from all of the foams is a 3-dimensional structure with a radius of gyration from 40 to 100{Angstrom}. By variation of the polymer molecular-weight, scattering data supports a model describing this nano-scale structure as partially isolated, collapsed polymer coils. This model indicates that collapsed base structural unit in these morphologies.

  9. Flexible Bistable Smectic-A Liquid Crystal Device Using Photolithography and Photoinduced Phase Separation

    Directory of Open Access Journals (Sweden)

    Yang Lu


    Full Text Available A flexible bistable smectic-A liquid crystal (SmA LC device using pixel-isolated mode was demonstrated, in which SmA LC molecules were isolated in pixels by vertical polymer wall and horizontal polymer layer. The above microstructure was achieved by using ultraviolet (UV photolithography and photoinduced phase separation. The polymer wall was fabricated by photolithography, and then the SmA LC was encapsulated in pixels between polymer wall through UV-induced phase separation, in which the polymer wall acts as supporting structure from mechanical pressure and maintains the cell gap from bending, and the polymer layer acts as adhesive for tight attachment of two substrates. The results demonstrated that all the intrinsic bistable properties of the SmA LC are preserved, and good electrooptical characteristics such as high contrast ratio and excellent stability of the bistable states were characterized. This kind of SmA bistable flexible display has high potential to be used as electronic paper, smart switchable reflective windows, and so forth.

  10. Thermally induced coupling of phase separation and gelation in an aqueous solution of hydroxypropylmethylcellulose (HPMC) (United States)

    Kita, Rio; Kaku, Takeshi; Ohashi, Hitoshi; Kurosu, Tateki; Iida, Masamori; Yagihara, Shin; Dobashi, Toshiaki


    Thermally induced coupling of gelation and phase separation in polysaccharide aqueous solutions has a complex feature because of critical and tricritical phenomena, thermally induced hydrophobic interaction, and molecular-weight distribution of the polysaccharide. To elucidate the process, the criticality of a hydroxypropylmethylcellulose (HPMC) aqueous solution was assessed, and then dielectric relaxation and fluorescence intensity experiments were carried out. The diffusion coefficient of the solution with a weight fraction of HPMC being 0.06 could be extrapolated to zero at the cloud-point curve which showed the criticality of the solution. The fluorescence intensity increased at a temperature much lower than the cloud point and the gel point, especially for concentrated solutions, indicating the hydrophobic interaction as the driving force of the gelation coupled by the phase separation. Dielectric relaxation measurements by time-domain reflectometry revealed two characteristic relaxations of chain motions around 100 MHz and orientation of free water around 20 GHz, which is accompanied by a low-frequency tail reflecting hydration water.

  11. Spontaneous phase separation during self-assembly in bi-dispersed spherical iron oxide nanoparticle monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Stanley, Jacob; Boucheron, Leandra; Shpyrko, Oleg, E-mail:, E-mail: [Department of Physics, University of California, San Diego, La Jolla, California 92093 (United States); Lin, Binhua, E-mail:, E-mail:; Meron, Mati [Center for Advanced Radiation Sources (CARS), University of Chicago, Chicago, Illinois 60637 (United States)


    Recent developments in the synthesis of iron oxide nanoparticles have resulted in the ability to fabricate roughly spherical particles with extremely high size uniformity (low polydispersity). These particles can form self-assembled monolayer films at an air-water interface. When the polydispersity of the particles is low, these monolayers can be well-ordered over a length scale dozens of times the particle size. The van der Waals force between the particles is what drives this self-assembly. Through the use of Grazing Incidence X-Ray Diffraction we demonstrate that, when these films are formed at the liquid surface from bi-dispersed solutions containing 10 and 20 nm spherical particles suspended in chloroform, the particles phase separate into well-ordered patches during the self-assembly process. Furthermore, the domain sizes of these phase separated regions are at most 2–3 times smaller than that of a film comprising only mono-dispersed particles and their degree of disorder is comparable. This is shown for multiple solutions with differing ratios of 10 and 20 nm particles.

  12. Homogeneous percolation versus arrested phase separation in attractively-driven nanoemulsion colloidal gels. (United States)

    Helgeson, Matthew E; Gao, Yongxiang; Moran, Shannon E; Lee, Jinkee; Godfrin, Michael; Tripathi, Anubhav; Bose, Arijit; Doyle, Patrick S


    We elucidate mechanisms for colloidal gelation of attractive nanoemulsions depending on the volume fraction (ϕ) of the colloid. Combining detailed neutron scattering, cryo-transmission electron microscopy and rheological measurements, we demonstrate that gelation proceeds by either of two distinct pathways. For ϕ sufficiently lower than 0.23, gels exhibit homogeneous fractal microstructure, with a broad gel transition resulting from the formation and subsequent percolation of droplet-droplet clusters. In these cases, the gel point measured by rheology corresponds precisely to arrest of the fractal microstructure, and the nonlinear rheology of the gel is characterized by a single yielding process. By contrast, gelation for ϕ sufficiently higher than 0.23 is characterized by an abrupt transition from dispersed droplets to dense clusters with significant long-range correlations well-described by a model for phase separation. The latter phenomenon manifests itself as micron-scale "pores" within the droplet network, and the nonlinear rheology is characterized by a broad yielding transition. Our studies reinforce the similarity of nanoemulsions to solid particulates, and identify important qualitative differences between the microstructure and viscoelastic properties of colloidal gels formed by homogeneous percolation and those formed by phase separation.

  13. Fabrication of Porous Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate Monoliths via Thermally Induced Phase Separation

    Directory of Open Access Journals (Sweden)

    Takashi Tsujimoto


    Full Text Available This study deals with the fabrication of biodegradable porous materials from bacterial polyester, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate (P3HB3HHx, via thermally induced phase separation. P3HB3HHx monoliths with topological porous structure were prepared by dissolution of P3HB3HHx in dimethyl sulfoxide (DMSO at 85 °C and subsequent quenching. The microstructure of the resulting P3HB3HHx monoliths was changed by the P3HB3HHx concentration of the polymer solution. Differential scanning calorimetry and polarized optical microscope analysis revealed that the P3HB3HHx monoliths crystallized during phase separation and the subsequent aging. The mechanical properties, such as compression modulus and stress, of the monoliths depended on the 3-hydroxyhexanoate content of P3HB3HHx. Furthermore, the P3HB3HHx monolith absorbed linseed oil in preference to water in a plant oil–water mixture. In combination with the biodegradable character of P3HB3HHx, the present study is expected to contribute to the development of bio-based materials.

  14. A New Strategy of Lithography Based on Phase Separation of Polymer Blends (United States)

    Guo, Xu; Liu, Long; Zhuang, Zhe; Chen, Xin; Ni, Mengyang; Li, Yang; Cui, Yushuang; Zhan, Peng; Yuan, Changsheng; Ge, Haixiong; Wang, Zhenlin; Chen, Yanfeng


    Herein, we propose a new strategy of maskless lithographic approach to fabricate micro/nano-porous structures by phase separation of polystyrene (PS)/Polyethylene glycol (PEG) immiscible polymer blend. Its simple process only involves a spin coating of polymer blend followed by a development with deionized water rinse to remove PEG moiety, which provides an extremely facile, low-cost, easily accessible nanofabrication method to obtain the porous structures with wafer-scale. By controlling the weight ratio of PS/PEG polymer blend, its concentration and the spin-coating speed, the structural parameters of the porous nanostructure could be effectively tuned. These micro/nano porous structures could be converted into versatile functional nanostructures in combination with follow-up conventional chemical and physical nanofabrication techniques. As demonstrations of perceived potential applications using our developed phase separation lithography, we fabricate wafer-scale pure dielectric (silicon)-based two-dimensional nanostructures with high broadband absorption on silicon wafers due to their great light trapping ability, which could be expected for promising applications in the fields of photovoltaic devices and thermal emitters with very good performances, and Ag nanodot arrays which possess a surface enhanced Raman scattering (SERS) enhancement factor up to 1.64 × 108 with high uniformity across over an entire wafer. PMID:26515790

  15. Interface control in organic heterojunction photovoltaic cells by phase separation processes (United States)

    Heier, Jakob; Castro, Fernando A.; Nüesch, Frank; Hany, Roland


    Significant progress is being made in the photovoltaic energy conversion using organic semiconducting materials. One of the focuses of attention is the nanoscale morphology of the donor-acceptor mixture, to ensure efficient charge generation and loss-free charge transport at the same time. Using small molecule and polymer blend systems, recent efforts highlight the problems to ensure an optimized relationship between molecular structure, morphology and device properties. Here, we present two examples using a host/guest mixture approach for the controlled, sequential design of bilayer organic solar cell architectures that consist of a large interface area with connecting paths to the respective electrodes at the same time. In the first example, we employed polymer demixing during spin coating to produce a rough interface: surface directed spinodal decomposition leads to a 2-dimensional spinodal pattern with submicrometer features at the polymer-polymer interface. The second system consists of a solution of a blend of small molecules, where phase separation into a bilayer during spin coating is followed by dewetting. For both cases, the guest can be removed using a selective solvent after the phase separation process, and the rough host surface can be covered with a second active, semiconducting component. We explain the potential merits of the resulting interdigitated bilayer films, and explore to which extent polymer-polymer and surface interactions can be employed to create surface features in the nanometer range.

  16. Self-optimized superconductivity attainable by interlayer phase separation at cuprate interfaces. (United States)

    Misawa, Takahiro; Nomura, Yusuke; Biermann, Silke; Imada, Masatoshi


    Stabilizing superconductivity at high temperatures and elucidating its mechanism have long been major challenges of materials research in condensed matter physics. Meanwhile, recent progress in nanostructuring offers unprecedented possibilities for designing novel functionalities. Above all, thin films of cuprate and iron-based high-temperature superconductors exhibit remarkably better superconducting characteristics (for example, higher critical temperatures) than in the bulk, but the underlying mechanism is still not understood. Solving microscopic models suitable for cuprates, we demonstrate that, at an interface between a Mott insulator and an overdoped nonsuperconducting metal, the superconducting amplitude is always pinned at the optimum achieved in the bulk, independently of the carrier concentration in the metal. This is in contrast to the dome-like dependence in bulk superconductors but consistent with the astonishing independence of the critical temperature from the carrier density x observed at the interfaces of La2CuO4 and La2-x Sr x CuO4. Furthermore, we identify a self-organization mechanism as responsible for the pinning at the optimum amplitude: An emergent electronic structure induced by interlayer phase separation eludes bulk phase separation and inhomogeneities that would kill superconductivity in the bulk. Thus, interfaces provide an ideal tool to enhance and stabilize superconductivity. This interfacial example opens up further ways of shaping superconductivity by suppressing competing instabilities, with direct perspectives for designing devices.

  17. Template-mediated synthesis of periodic membranes for improved liquid-phase separations

    Energy Technology Data Exchange (ETDEWEB)

    Groger, H. [American Research Corp. of Virginia, Radford, VA (United States)


    Solid/liquid separations of particulates in waste streams will benefit from design and development of ultrafiltration (UF) membranes with uniform, tailorable pore size and chemical, thermal, and mechanical stability. Such membranes will perform solid/liquid separations with high selectivity, permeance, lifetime, and low operating costs. Existing organic and inorganic membrane materials do not adequately meet all these requirements. An innovative solution to the need for improved inorganic membranes is the application of mesoporous ceramics with narrow pore-size distributions and tailorable pore size (1.5 to 10 nm) that have recently been shown to form with the use of organic surfactant molecules and surfactant assemblies as removable templates. This series of porous ceramics, designated MCM-41, consists of silica or aluminosilicates distinguished by periodic arrays of uniform channels. In this Phase I Small Business Innovation Research program, American Research Corporation of Virginia will demonstrate the use of supported MCM-41 thin films deposited by a proprietary technique, as UF membranes. Technical objectives include deposition in thin, defect-free periodic mesoporous MCM-41 membranes on porous supports; measurement of membrane separation factors, permeance, and fouling; and measurement of membrane lifetime as part of an engineering and economic analysis.

  18. Phase-space consistency of stellar dynamical models determined by separable augmented densities

    CERN Document Server

    An, J; Baes, M


    Assuming the separable augmented density, it is always possible to construct a distribution function of a spherical population with any given density and anisotropy. We consider under what conditions the distribution constructed as such is in fact non-negative everywhere in the accessible phase-space. We first generalize known necessary conditions on the augmented density using fractional calculus. The condition on the radius part R(r^2) (whose logarithmic derivative is the anisotropy parameter) is equivalent to the complete monotonicity of R(1/w)/w. The condition on the potential part on the other hand is given by its derivative up to any order not greater than (3/2-beta) being non-negative where beta is the central anisotropy parameter. We also derive a specialized inversion formula for the distribution from the separable augmented density, which leads to sufficient conditions on separable augmented densities for the non-negativity of the distribution. The last generalizes the similar condition derived earl...

  19. Discrete phase model representation of particulate matter (PM) for simulating PM separation by hydrodynamic unit operations. (United States)

    Dickenson, Joshua A; Sansalone, John J


    Modeling the separation of dilute particulate matter (PM) has been a topic of interest since the introduction of unit operations for clarification of rainfall-runoff. One consistent yet controversial issue is the representation of PM and PM separation mechanisms for treatment. While Newton's Law and surface overflow rate were utilized, many historical models represented PM as a lumped gravimetric index largely out of economy and lack of particle analysis methods. As a result such models did not provide information about particle fate in or through a unit operation. In this study, PM discrete phase modeling (DPM) and computational fluid dynamics (CFD) are applied to model PM fate as a function of particle size and flow rate in two common types of hydrodynamic separator (HS) units. The study examines the discretization requirements (as a discretization number, DN) and errors for particle size distributions (PSDs) that range from the common heterodisperse to a monodisperse PSD. PSDs are categorized based on granulometric indices. Results focus on ensuring modeling accuracy while examining the role of size dispersivity and overall PM fineness on DN requirements. The fate of common heterodisperse PSDs is accurately predicted for a DN of 16, whereas a single particle size index, commonly the d(50m), is limited to monodisperse PSDs in order to achieve similar accuracy.

  20. A new formulation of the phase change approach in the theory of conical intersections

    Energy Technology Data Exchange (ETDEWEB)

    Vanni, Stefano [Department of Chemistry, Imperial College London, London SW7 2AZ (United Kingdom); Garavelli, Marco [Dipartimento di Chimica ' G. Ciamician' , Universita di Bologna, via Selmi 2, Bologna I-40126 (Italy); Robb, Michael A. [Department of Chemistry, Imperial College London, London SW7 2AZ (United Kingdom)], E-mail:


    We have reformulated the phase change approach to the theory of conical intersections suggested by Zilberg and Haas [S. Zilberg, Y. Haas, Adv. Chem. Phys. 124 (2002) 433]. We use the fact that the phase change loop variable {phi} in polar co-ordinates in the space of nuclear co-ordinates is related to the transformation ({theta}=({phi})/2 ) of the diabatic VB states defined at the apex of the cone in a conical intersection. Thus one can use the basis transformation generated by {theta} to yield a sequence of orthogonal pairs of VB structures (anchors) at any value of {phi} in the loop in nuclear configuration space. In this way the branching plane concept becomes related to VB wavefunctions based on the correspondence between the two angles. The theory is developed in detail using a simple three orbital three electron example. Examples are presented for four and six orbitals. In the later case, our results differ from those of Zilberg and Haas.

  1. Probing interactions and phase separations of proteins, colloids, and polymers with light scattering (United States)

    Parmar, Avanish Singh

    The broad objective of my research is to investigate the physical characteristics and interactions of macromolecules and nanoparticles, and the corresponding effects on their phase separation behavior using static and dynamic light scattering (SLS & DLS). Light scattering provides a non-invasive technique for monitoring the in-situ behavior of solutes in solution, including solute interactions, sizes, shapes, aggregation kinetics and even rheological properties of condensed phases. Initially, we investigated lysozyme solutions for the presence of preformed aggregates and clusters that can distort the kinetics of protein crystal nucleation studies in this important model system for protein crystallization. We found that both undersaturated and supersaturated lysozyme solutions contained population of large, pre-existing protein aggregate. Separating these clusters and analyzing their composition with gel chromatography indicated that these clusters represented pre-formed lysozyme aggregates, and not extrinsic protein contamination. We investigated the effect of chaotropic versus kosmotropic ions (water structure breakers vs. structure makers) on the hydration layer and hydrodynamic interactions of hen egg white lysozyme. Surprisingly, neither chaotropic nor kosmotropic ions affected the protein hydration layer. Salt-effects on direct and hydrodynamic protein interactions were determined as function of the solutions ionic strength and temperature. Using both static and dynamic light scattering, we investigated the nucleation of gold nanoparticles forming from supersaturated gold sols. We observed that two well separated populations of nuclei formed essentially simultaneously, with sizes of 3nm vs. several tens of nanometer, respectively. We explore the use of lysozyme as tracer particle for diffusion-base measurements of electrolyte solutions. We showed that the unusual stability of lysozyme and its enhanced colloidal stability enable viscosity measurement of salts

  2. Modification of linear prepolymers to tailor heterogeneous network formation through photo-initiated Polymerization-Induced Phase Separation. (United States)

    Szczepanski, Caroline R; Stansbury, Jeffrey W


    Polymerization-induced phase separation (PIPS) was studied in ambient photopolymerizations of triethylene glycol dimethacrylate (TEGDMA) modified by poly(methyl methacrylate) (PMMA). The molecular weight of PMMA and the rate of network formation (through incident UV-irradiation) were varied to influence both the promotion of phase separation through increases in overall free energy, as well as the extent to which phase development occurs during polymerization through diffusion prior to network gelation. The overall free energy of the polymerizing system increases with PMMA molecular weight, such that PIPS is promoted thermodynamically at low loading levels (5 wt%) of a higher molecular weight PMMA (120 kDa), while a higher loading level (20 wt%) is needed to induce PIPS with lower PMMA molecular weight (11 kDa), and phase separation was not promoted at any loading level tested of the lowest molecular weight PMMA (1 kDa). Due to these differences in overall free energy, systems modified by PMMA (11 kDa) underwent phase separation via Nucleation and Growth, and systems modified by PMMA (120 kDa), followed the Spinodal Decomposition mechanism. Despite differences in phase structure, all materials form a continuous phase rich in TEGDMA homopolymer. At high irradiation intensity (Io=20mW/cm(2)), the rate of network formation prohibited significant phase separation, even when thermodynamically preferred. A staged curing approach, which utilizes low intensity irradiation (Io=300µW/cm(2)) for the first ~50% of reaction to allow phase separation via diffusion, followed by a high intensity flood-cure to achieve a high degree of conversion, was employed to form phase-separated networks with reduced polymerization stress yet equivalent final conversion and modulus.

  3. Numerical study of the phase separation in binary lipid membrane containing protein inclusions under stationary shear flow. (United States)

    Chen, Xiao-Bo; Shi, Hui-Ji; Niu, Li-Sha


    The phase separation of lipids is believed to be responsible for the formation of lipid rafts in biological cell membrane. In the present work, a continuum model and a particle model are constructed to study the phase separation in binary lipid membrane containing inclusions under stationary shear flow. In each model, employing the cell dynamical system (CDS) approach, the kinetic equations of the confusion-advection process are numerically solved. Snapshot figures of the phase morphology are performed to intuitively display such phase evolving process. Considering the effects from both the inclusions and the shear flow, the time growth law of the characteristic domain size is discussed.

  4. Renormalization-Group Theory Study of Superfluidity and Phase Separation of Helium Mixtures Immersed in Jungle-Gym Aerogel (United States)

    Lopatnikova, Anna; Berker, A. Nihat


    Superfluidity and phase separation in ^3He-^4He mixtures immersed in jungle-gym (non-random) aerogel are studied by renormalization-group theory.(Phys. Rev. B, in press (1996)) Phase diagrams are calculated for a variety of aerogel concentrations. Superfluidity at very low ^4He concentrations and a depressed tricritical temperature are found at the onset of superfluidity. A superfluid-superfluid phase separation, terminating at an isolated critical point, is found entirely within the superfluid phase. These phenomena, and trends with respect to aerogel concentration, are explained by the connectivity and tenuousness of jungle-gym aerogel.

  5. Phase-space noncommutative extension of the Robertson-Schroedinger formulation of Ozawa's uncertainty principle

    CERN Document Server

    Bastos, Catarina; Bertolami, Orfeu; Dias, Nuno Costa; Prata, João Nuno


    We revisit Ozawa's uncertainty principle (OUP) in the framework of noncommutative (NC) quantum mechanics. We derive a matrix version of OUP accommodating any NC structure in the phase-space, and compute NC corrections to lowest order for two measurement interactions, namely the Backaction Evading Quadrature Amplifier and Noiseless Quadrature Transducers. These NC corrections alter the nature of the measurement interaction, as a noiseless interaction may acquire noise, and an interaction of independent intervention may become dependent of the object system. However the most striking result is that noncommutativity may lead to a violation of the OUP itself. The NC corrections for the Backaction Evading Quadrature Amplifier reveal a new term which may potentially be amplified in such a way that the violation of the OUP becomes experimentally testable. On the other hand, the NC corrections to the Noiseless Quadrature Transducer shows an incompatibility of this model with NC quantum mechanics. We discuss the impli...

  6. Density functional theory of gas-liquid phase separation in dilute binary mixtures (United States)

    Okamoto, Ryuichi; Onuki, Akira


    We examine statics and dynamics of phase-separated states of dilute binary mixtures using density functional theory. In our systems, the difference of the solvation chemical potential between liquid and gas Δ {μ\\text{s}} (the Gibbs energy of transfer) is considerably larger than the thermal energy {{k}\\text{B}}T for each solute particle and the attractive interaction among the solute particles is weaker than that among the solvent particles. In these conditions, the saturated vapor pressure increases by {{k}\\text{B}}Tn2\\ell\\exp ≤ft(Δ {μ\\text{s}}/{{k}\\text{B}}T\\right) , where n2\\ell is the solute density added in liquid. For \\exp ≤ft(Δ {μ\\text{s}}/{{k}\\text{B}}T\\right)\\gg 1 , phase separation is induced at low solute densities in liquid and the new phase remains in gaseous states, even when the liquid pressure is outside the coexistence curve of the solvent. This explains the widely observed formation of stable nanobubbles in ambient water with a dissolved gas. We calculate the density and stress profiles across planar and spherical interfaces, where the surface tension decreases with increasing interfacial solute adsorption. We realize stable solute-rich bubbles with radius about 30 nm, which minimize the free energy functional. We then study dynamics around such a bubble after a decompression of the surrounding liquid, where the bubble undergoes a damped oscillation. In addition, we present some exact and approximate expressions for the surface tension and the interfacial stress tensor.

  7. Study of Phase Separation of Poly(N-isopropylacrylamide-co-styrene) Aqueous Solutions with Rayleigh Scattering Technique

    Institute of Scientific and Technical Information of China (English)

    Yi Guobin; Zhu Zhenghong; Wang Fei; Chen Xudong; Yang Jin; Huang Yunwei


    A thermally sensitive copolymer, poly(N-isopropylacrylamfide-co-styrene) [P(NIPAM-co-St)] (Mn=9.5×105 g/mol and Mw/Mn= 1.51) was synthesized by soap-free emulsion polymerization. The phase separation of the co-polymer in water was investigated by Rayleigh scattering (RS) technique. The RS spectra revealed the transition of molecular conformation and the aggregation of molecular chains in the course of phase separation. The coil-to-globule and globule-to-coil transitions of P(NIPAM-co-St) chains were found in one heating-and-cooling cycle. By means of Avrami formula, apparent activation energy of phase separation of P(NIPAM-co-St) aqueous solutions was estimated. Moreover, a model was proposed to describe the phase separation process.

  8. Polymerization-induced phase separation in polyether-sulfone modified epoxy resin systems: effect of curing reaction mechanism

    Institute of Scientific and Technical Information of China (English)


    Polyethersulfone (PES)-modified epoxy systems with stepwise reaction were studied throughout the entire curing process by using optical microscopes, time-resolved light scattering (TRLS), and a rheolometry instrument compared with that of chainwise polymerization. The results suggested that the phase separation process is mainly controlled by the diffusion of epoxy oligomers for stepwise mechanism system and by that of epoxy monomers for chainwise mechanism system. In case of high PES content (SPES-20%) light-scattering results showed a viscoelastic phase separation and the characteristic relaxation time of phase separation can be described well by the WLF equation. However, in the case of low PES content (SPES-14%) secondary phase separation phenomenon was observed by Optical Microscope and further demonstrated by rheological study.

  9. Separation of chiral primary amino compounds by forming a sandwiched complex in reversed-phase high performance liquid chromatography. (United States)

    Zhang, Chen; Huang, Wei X; Chen, Zhi; Rustum, Abu M


    Separation of chiral primary amino compounds was efficiently achieved under reversed-phase high performance liquid chromatography (RP-HPLC) conditions using a mixture of non-chiral crown ether (18-crown-6) and dimethyl-beta-cyclodextrin (DM-beta-CD) in the mobile phase. Under these conditions, the amino group of the chiral compound was protonated in a low pH mobile phase, and then interacted with 18-crown-6 and DM-beta-CD to form a sandwiched complex [18-crown-6+amine+CD]. Enantiomers of the compound in the sandwiched complex were separated with good enantioselectivity. Formation of the sandwiched complex among the chiral compound and additives in the mobile phase is a key step of the chiral separation. Four different chiral amino compounds namely, 1-aminoindan (AI), 1,2,3,4-tetrahydro-1-naphthylamine (THNA), tyrosine (Tyr), and phenylalanine (Phe), were selected to demonstrate the separation using the sandwiched complex mechanism in RP-HPLC.

  10. Enantioselective and diastereoselective separation of synthetic pyrethroid insecticides on a novel chiral stationary phase by high-performance liquid chromatography. (United States)

    Tan, Xulin; Hou, Shicong; Wang, Min


    A novel chiral packing material for high-performance liquid chromatography (HPLC) was prepared by connecting (R)-1-phenyl-2-(4-methylphenyl) ethylamine (PTE) amide derivative of (S)-isoleucine to aminopropyl silica gel through 2-amino-3,5-dinitro-1-carboxamido-benzene unit. This chiral stationary phase was applied to the enantioselective and diastereoselective separation of five pyrethroid insecticides by HPLC under normal phase condition. To achieve satisfactory baseline separation an optimization of the variables of mobile phase composition was required. The two enantiomers of fenpropathrin and four stereoisomers of fenvalerate were baseline separated using hexane-1,2-dichloroethane-2-propanol as mobile phase. The results show that the enantioselectivity of CSP is better than Pirkle type 1-A column for these compounds. Only partial separations for the cypermethrin and cyfluthrin stereoisomers were observed. Seven peaks and eight peaks were observed for cypermethrin and cyfluthrin, respectively. The elution orders were assigned by using different stereoisomer-enriched products.

  11. Determination of vertical phase separation in a polyfluorene copolymer : fullerene derivative solar cell blend by X-ray photoelectron spectroscopy

    NARCIS (Netherlands)

    Felicissimo, Marcella Passos; Jarzab, Dorota; Gorgoi, Mihaela; Forster, Michael; Scherf, Ullrich; Scharber, Markus C.; Svensson, Svante; Rudolf, Petra; Loi, Maria Antonietta


    A vertical phase separation is evidenced using high-kinetic-energy X-ray photoelectron spectroscopy at different photon energies in a polyfluorene copolymer:C(60) derivative blend relevant for photovoltaic application.

  12. Separation of Corn Fiber and Conversion to Fuels and Chemicals Phase II: Pilot-scale Operation

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, Charles; Beery, Kyle; Orth, Rick; Zacher, Alan


    The purpose of the Department of Energy (DOE)-supported corn fiber conversion project, “Separation of Corn Fiber and Conversion to Fuels and Chemicals Phase II: Pilot-scale Operation” is to develop and demonstrate an integrated, economical process for the separation of corn fiber into its principal components to produce higher value-added fuel (ethanol and biodiesel), nutraceuticals (phytosterols), chemicals (polyols), and animal feed (corn fiber molasses). This project has successfully demonstrated the corn fiber conversion process on the pilot scale, and ensured that the process will integrate well into existing ADM corn wet-mills. This process involves hydrolyzing the corn fiber to solubilize 50% of the corn fiber as oligosaccharides and soluble protein. The solubilized fiber is removed and the remaining fiber residue is solvent extracted to remove the corn fiber oil, which contains valuable phytosterols. The extracted oil is refined to separate the phytosterols and the remaining oil is converted to biodiesel. The de-oiled fiber is enzymatically hydrolyzed and remixed with the soluble oligosaccharides in a fermentation vessel where it is fermented by a recombinant yeast, which is capable of fermenting the glucose and xylose to produce ethanol. The fermentation broth is distilled to remove the ethanol. The stillage is centrifuged to separate the yeast cell mass from the soluble components. The yeast cell mass is sold as a high-protein yeast cream and the remaining sugars in the stillage can be purified to produce a feedstock for catalytic conversion of the sugars to polyols (mainly ethylene glycol and propylene glycol) if desirable. The remaining materials from the purification step and any materials remaining after catalytic conversion are concentrated and sold as a corn fiber molasses. Additional high-value products are being investigated for the use of the corn fiber as a dietary fiber sources.

  13. Separation of Corn Fiber and Conversion to Fuels and Chemicals Phase II: Pilot-scale Operation

    Energy Technology Data Exchange (ETDEWEB)

    Abbas, Charles; Beery, Kyle; Orth, Rick; Zacher, Alan


    The purpose of the Department of Energy (DOE)-supported corn fiber conversion project, “Separation of Corn Fiber and Conversion to Fuels and Chemicals Phase II: Pilot-scale Operation” is to develop and demonstrate an integrated, economical process for the separation of corn fiber into its principal components to produce higher value-added fuel (ethanol and biodiesel), nutraceuticals (phytosterols), chemicals (polyols), and animal feed (corn fiber molasses). This project has successfully demonstrated the corn fiber conversion process on the pilot scale, and ensured that the process will integrate well into existing ADM corn wet-mills. This process involves hydrolyzing the corn fiber to solubilize 50% of the corn fiber as oligosaccharides and soluble protein. The solubilized fiber is removed and the remaining fiber residue is solvent extracted to remove the corn fiber oil, which contains valuable phytosterols. The extracted oil is refined to separate the phytosterols and the remaining oil is converted to biodiesel. The de-oiled fiber is enzymatically hydrolyzed and remixed with the soluble oligosaccharides in a fermentation vessel where it is fermented by a recombinant yeast, which is capable of fermenting the glucose and xylose to produce ethanol. The fermentation broth is distilled to remove the ethanol. The stillage is centrifuged to separate the yeast cell mass from the soluble components. The yeast cell mass is sold as a high-protein yeast cream and the remaining sugars in the stillage can be purified to produce a feedstock for catalytic conversion of the sugars to polyols (mainly ethylene glycol and propylene glycol) if desirable. The remaining materials from the purification step and any materials remaining after catalytic conversion are concentrated and sold as a corn fiber molasses. Additional high-value products are being investigated for the use of the corn fiber as a dietary fiber sources.

  14. Enantiomeric separation of iridium (III) complexes using HPLC chiral stationary phases based on amylose derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hee Eun; Seo, Na Hyeon; Hyun, Myung Ho [Dept. of Chemistry and Chemistry Institute for Functional Materials, Pusan National University, Busan (Korea, Republic of)


    Cyclometalated iridium (III) complexes formed with three identical cyclometalating (C-N) ligands (homoleptic) or formed with two cyclometalating (C-N) ligands and one ancillary (LX) ligand (heteroleptic) have been known as highly phosphorescent materials and, thus, they have been utilized as efficient phosphorescent dopants in organic light emitting diodes (OLEDs) 1–3 or as effective phosphorescent chemosensors. 4–7 Cylometalated iridium (III) complexes are chiral compounds consisting of lambda (Λ, left-handed) and delta (Δ, right-handed) isomers. Racemic cyclometa- lated iridium (III) complexes emit light with no net polarization, but optically active cyclometalated iridium (III) complexes emit circularly polarized light. 8,9 Circularly polarized light can be used in various fields including highly efficient three dimensional electronic devices, photo nic devices for optical data storage, biological assays, and others. 8,9 In order to obtain optically active cylometalated iridium (III) complexes and to determine the enantiomeric composition of optically active cylometalated iridium (III) complexes, liquid chromatogr aphic enantiomer separation method on chiral stationary phases (CSPs) has been used. For example, Okamoto and coworkers first reported the high performance liquid chromatographic (HPLC) direct enantiomeric separation of two homoleptic cylometalated iridium (III) complexes on immobilized amylose tris(3,5- dimethylphenylcarbamate) (Chiralpak IA), coated cellulose tris(3,5-dimethylphenylcarbamate) (Chiralc el OD), and coated cellulose tris(4-methylbenzoate) (Chiralce l OJ). 10 Supercritical fluid chromatography (SFC) was also used by Bernhard and coworkers for the enantiomeric separation of cylometalated iridium (III) complexes on coated amylose tris(3,5-dimethylphenylcarbamate) (Chiralpak AD-H). 8 However, the general use of the HPLC method for the direct enantiomeric separation of homoleptic.

  15. Development of a validated RP-LC/ESI-MS-MS method for separation, identification and determination of related substances of tamsulosin in bulk drugs and formulations. (United States)

    Nageswara Rao, R; Kumar Talluri, M V N; Narasa Raju, A; Shinde, Dhananjay D; Ramanjaneyulu, G S


    A reversed-phase high performance liquid chromatographic (RP-HPLC) method for evaluation of purity of tamsulosin in bulk drugs and pharmaceuticals was developed. The separation was accomplished on an Inertsil C(18) column using 10 mM ammonium acetate: acetonitrile as a mobile phase in a gradient elution mode. A photodiode array detector set at 280 nm was used for detection. The impurities were identified by ESI-MS-MS. The detection limits were 0.06-0.11 microg/ml. The method was validated with respect to accuracy, precision, linearity, ruggedness and limits of detection and quantification. It finds application not only for monitoring the reactions during the process development but also on quality assurance of tamsulosin.

  16. Charge ordering and phase separation in the infinite dimensional extended Hubbard model (United States)

    Tong, Ning-Hua; Shen, Shun-Qing; Bulla, Ralf


    We study the extended Hubbard model with both on-site (U) and nearest neighbor (V) Coulomb repulsion using the exact diagonalization method within the dynamical mean field theory. For a fixed U (U=2.0) , the T-n phase diagrams are obtained for V=1.4 and V=1.2 , at which the ground state of n=1/2 system is charge-ordered and charge-disordered, respectively. In both cases, robust charge order is found at finite temperature and in an extended filling regime around n=1/2 . The order parameter changes nonmonotonously with temperature. For V=1.4 , phase separation between charge-ordered and charge-disordered phases is observed in the low temperature and n<0.5 regime. It is described by an “S”-shaped structure of the n-μ curve. For V=1.2 , the ground state is charge-disordered, and a reentrant charge-ordering transition is observed for 0.42

  17. Removal of primary iron rich phase from aluminum-silicon melt by centrifugal separation

    Directory of Open Access Journals (Sweden)

    Seong Woo Kim


    Full Text Available Recycling is a major consideration in continued aluminum use due to the enormous demand for high quality products. Some impurity elements gradually accumulate through the repetitive reuse of aluminum alloy scrap. Of them, the iron content should be suppressed under the allowed limit. In the present research, a novel separation method was introduced to remove primary iron-rich intermetallic compounds by centrifugation during solidification of Al-Si-Fe alloys. This method does not use the density difference between two phases as in other centrifugal methods, but uses the order of solidification in Al-Si-Fe alloys, because iron promotes the formation of intermetallic compounds with other alloying elements as a primary phase. Two Al-Si-Fe alloys which have different iron contents were chosen as the starting materials. The iron-rich phase could be efficiently removed by centrifuging under a centrifugal force of 40 g. Coarse intermetallic compounds were found in the sample inside the crucible, while rather fine intermetallic compounds were found in the sample outside the crucible. Primary intermetallic compounds were linked to each other via aluminum-rich matrix, and formed like a network. The highest iron removal fraction is 67% and the lowest one is 7% for Al-12Si-1.7Fe alloy. And they are 82% and 18% for Al-12Si-3.4Fe alloy, respectively.

  18. Tunnelling magnetoresistance and 1/f noise in phase-separated manganites

    CERN Document Server

    Sboychakov, A O; Kugel, K I; Kagan, M Y; Brodsky, I V


    The magnetoresistance and the noise power of non-metallic phase-separated manganites are studied. The material is modelled by a system of small ferromagnetic metallic droplets (magnetic polarons or ferrons) in an insulating matrix. The concentration of metallic phase is assumed to be far from the percolation threshold. The electron tunnelling between ferrons causes the charge transfer in such a system. The magnetoresistance is determined both by the increase in the volume of the metallic phase and by the change in the electron hopping probability. In the framework of such a model, the low-field magnetoresistance is proportional to H sup 2 and decreases with temperature as T sup - sup n , where n can vary from 1 to 5, depending on the parameters of the system. In the high-field limit, the tunnelling magnetoresistance grows exponentially. Different mechanisms of the voltage fluctuations in the system are analysed. The noise spectrum generated by the fluctuations of the number of droplets with extra electrons ha...

  19. Hydration-Induced Phase Separation in Amphiphilic Polymer Matrices and its Influence on Voclosporin Release

    Energy Technology Data Exchange (ETDEWEB)

    Khan, I. John [The State Univ. of New Jersey, Piscataway, NJ (United States); Murthy, N. Sanjeeva [The State Univ. of New Jersey, Piscataway, NJ (United States); Kohn, Joachim [The State Univ. of New Jersey, Piscataway, NJ (United States)


    Voclosporin is a highly potent, new cyclosporine -- a derivative that is currently in Phase 3 clinical trials in the USA as a potential treatment for inflammatory diseases of the eye. Voclosporin represents a number of very sparingly soluble drugs that are difficult to administer. It was selected as a model drug that is dispersed within amphiphilic polymer matrices, and investigated the changing morphology of the matrices using neutron and x-ray scattering during voclosporin release and polymer resorption. The hydrophobic segments of the amphiphilic polymer chain are comprised of desaminotyrosyl-tyrosine ethyl ester (DTE) and desaminotyrosyl-tyrosine (DT), and the hydrophilic component is poly(ethylene glycol) (PEG). Water uptake in these matrices resulted in the phase separation of hydrophobic and hydrophilic domains that are a few hundred Angstroms apart. These water-driven morphological changes influenced the release profile of voclosporin and facilitated a burst-free release from the polymer. No such morphological reorganization was observed in poly(lactide-co-glycolide) (PLGA), which exhibits an extended lag period, followed by a burst-like release of voclosporin when the polymer was degraded. An understanding of the effect of polymer composition on the hydration behavior is central to understanding and controlling the phase behavior and resorption characteristics of the matrix for achieving long-term controlled release of hydrophobic drugs such as voclosporin.

  20. Thermal Evolution of the Inhomogeneous Jovian Planets: The Effects of Helium Phase Separation (United States)

    Mankovich, Christopher; Fortney, Jonathan; Moore, Kevin; Nettelmann, Nadine


    We compute evolutionary models of Jupiter and Saturn including the effects of helium phase separation in the deep interior. The aim is to simultaneously match each planet's present-day luminosity and surface helium abundance, which are at odds with homogeneous, adiabatic thermal evolution. The calculations are carried out using the open source MESA code, extended to include a modern phase diagram for hydrogen/helium mixtures at high pressures and a self-consistent radiative atmosphere grid for each planet. We find that if He redistribution proceeds much faster than a convective circulation time, then the composition gradient established between one and a few Mbar stabilizes the fluid against convection. In this region the heat is transported less efficiently by overstable double-diffusive convection, which we implement following recent 3D hydrodynamics simulations of the instability. The onset and evolution of this superadiabatic barrier region between the hot, He-rich inner adiabat and the cool, He-depleted outer adiabat bears directly on the cooling histories, especially that of Saturn. The upcoming measurement of Saturn's atmospheric He abundance expected of Cassini will place constraints on both the extent of the convectively stable region in Saturn and the general H/He phase diagram which informs the thermal evolution of all giant planets. We discuss implications for the dynamo within each planet, and ring seismology for Saturn.

  1. Correspondence between the electronic structure and phase separation in a K-doped FeSe system (United States)

    Liu, C.; Zhao, J. L.; Wang, J. O.; Qian, H. J.; Wu, R.; Wang, H. H.; Zhang, N.; Ibrahim, K.


    Phase separated potassium intercalated FeSe thin films have been synthesized by pulsed laser deposition. The coexistence of FeSe phase and 245 phase was investigated both by x-ray photoemission spectroscopy (XPS) and x-ray diffraction. The volume ratio of these two phases is sensitive to temperatures and amount of extra potassium dosing. The XPS and ultraviolet photoelectron spectroscopy results indicated that these two phases shows the different hybridization strength between adjacent Fe layer and Se layer. We infer that the layered electronic structure is the necessary condition of superconductivity in potassium-doped FeSe system, and the phase separation is driven by competition between quasi-2D and 3D bonding mode within FeSe layer. Similar competition may also be able to interpret the phase seperation in K x Fe2-y Se2 bulk single crystal. Project supported under 11375228 by NSFC and 2016YFA0401002 by MOST of China.

  2. A new treatment of capillarity to improve the stability of IMPES two-phase flow formulation

    KAUST Repository

    Kou, Jisheng


    In this paper, we present an efficient numerical method for two-phase immiscible flow in porous media with different capillarity pressures. In highly heterogeneous permeable media, the saturation is discontinuous due to different capillary pressure functions. One popular scheme is to split the system into a pressure and a saturation equation, and to apply IMplicit Pressure Explicit Saturation (IMPES) approach for time stepping. One disadvantage of IMPES is instability resulting from the explicit treatment for capillary pressure. To improve stability, the capillary pressure is usually incorporated in the saturation equation which gradients of saturation appear. This approach, however, does not apply to the case of different capillary pressure functions for multiple rock-types, because of the discontinuity of saturation across rock interfaces. In this paper, we present a new treatment of capillary pressure, which appears implicitly in the pressure equation. Using an approximation of capillary function, we substitute the implicit saturation equation into the pressure equation. The coupled pressure equation will be solved implicitly and followed by the explicit saturation equation. Five numerical examples are provided to demonstrate the advantages of our approach. Comparison shows that our proposed method is more efficient and stable than the classical IMPES approach. © 2010 Elsevier Ltd.

  3. A Capillary-Based Static Phase Separator for Highly Variable Wetting Conditions (United States)

    Thomas, Evan A.; Graf, John C.; Weislogel, Mark M.


    The invention, a static phase separator (SPS), uses airflow and capillary wetting characteristics to passively separate a two-phase (liquid and air) flow. The device accommodates highly variable liquid wetting characteristics. The resultant design allows for a range of wetting properties from about 0 to over 90 advancing contact angle, with frequent complete separation of liquid from gas observed when using appropriately scaled test conditions. Additionally, the design accommodates a range of air-to-liquid flow-rate ratios from only liquid flow to over 200:1 air-to-liquid flow rate. The SPS uses a helix input section with an ice-cream-cone-shaped constant area cross section (see figure). The wedge portion of the cross section is on the outer edge of the helix, and collects the liquid via centripetal acceleration. The helix then passes into an increasing cross-sectional area vane region. The liquid in the helix wedge is directed into the top of capillary wedges in the liquid containment section. The transition from diffuser to containment section includes a 90 change in capillary pumping direction, while maintaining inertial direction. This serves to impinge the liquid into the two off-center symmetrical vanes by the airflow. Rather than the airflow serving to shear liquid away from the capillary vanes, the design allows for further penetration of the liquid into the vanes by the air shear. This is also assisted by locating the air exit ports downstream of the liquid drain port. Additionally, any droplets not contained in the capillary vanes are re-entrained downstream by a third opposing capillary vane, which directs liquid back toward the liquid drain port. Finally, the dual air exit ports serve to slow the airflow down, and to reduce the likelihood of shear. The ports are stove-piped into the cavity to form an unfriendly capillary surface for a wetting fluid to carryover. The liquid drain port is located at the start of the containment region, allowing for

  4. Flow-parametric regulation of shear-driven phase separation in two and three dimensions (United States)

    Ã` Náraigh, Lennon; Shun, Selma; Naso, Aurore


    The Cahn-Hilliard equation with an externally prescribed chaotic shear flow is studied in two and three dimensions. The main goal is to compare and contrast the phase separation in two and three dimensions, using high-resolution numerical simulation as the basis for the study. The model flow is parametrized by its amplitudes (thereby admitting the possibility of anisotropy), length scales, and multiple time scales, and the outcome of the phase separation is investigated as a function of these parameters as well as the dimensionality. In this way, a parameter regime is identified wherein the phase separation and the associated coarsening phenomenon are not only arrested but in fact the concentration variance decays, thereby opening up the possibility of describing the dynamics of the concentration field using the theories of advection diffusion. This parameter regime corresponds to long flow correlation times, large flow amplitudes and small diffusivities. The onset of this hyperdiffusive regime is interpreted by introducing Batchelor length scales. A key result is that in the hyperdiffusive regime, the distribution of concentration (in particular, the frequency of extreme values of concentration) depends strongly on the dimensionality. Anisotropic scenarios are also investigated: for scenarios wherein the variance saturates (corresponding to coarsening arrest), the direction in which the domains align depends on the flow correlation time. Thus, for correlation times comparable to the inverse of the mean shear rate, the domains align in the direction of maximum flow amplitude, while for short correlation times, the domains initially align in the opposite direction. However, at very late times (after the passage of thousands of correlation times), the fate of the domains is the same regardless of correlation time, namely alignment in the direction of maximum flow amplitude. A theoretical model to explain these features is proposed. These features and the theoretical

  5. Development of a novel amide-silica stationary phase for the reversed-phase HPLC separation of different classes of phytohormones. (United States)

    Aral, Hayriye; Aral, Tarık; Ziyadanoğulları, Berrin; Ziyadanoğulları, Recep


    A novel amide-bonded silica stationary phase was prepared starting from N-Boc-phenylalanine, cyclohexylamine and spherical silica gel (4 µm, 60 Å). The amide ligand was synthesised with high yield. The resulting amide bonded stationary phase was characterised by SEM, IR and elemental analysis. The resulting selector bearing a polar amide group is used for the reversed-phase chromatography separation of different classes of thirteen phytohormones (plant hormones). The chromatographic behaviours of these analytes on the amide-silica stationary phase were compared with those of RP-C18 column under same conditions. The effects of different separation conditions, such as mobile phase, pH value, flow rate and temperature, on the separation and retention behaviours of the 13 phytohormones in this system were studied. The optimum separation was achieved using reversed-phase HPLC gradient elution with an aqueous mobile phase containing pH=6.85 potassium phosphate buffer (20 mM) and acetonitrile with a 22 °C column temperature. Under these experimental conditions, the 12 phytohormones could be separated and detected at 230 or 270 nm within 26 min.

  6. New upscaled equations for multiphase flows in porous media based on a phase field formulation for general free energies (United States)

    Schmuck, Markus; Pradas, Marc; Pavliotis, Grigorios A.; Kalliadasis, Serafim


    Based on thermodynamic and variational principles we formulate novel equations for mixtures of incompressible fluids in strongly heterogeneous domains, such as composites and porous media, using elements from the regular solution theory. Starting with equations that fully resolve the pores of a porous medium, represented as a periodic covering of a single reference pore, we rigorously derive effective macroscopic phase field equations under the assumption of periodic and strongly convective flow. Our derivation is based on the multiple scale method with drift and our recently introduced splitting strategy for Ginzburg-Landau/Cahn-Hilliard-type equations. We discover systematically diffusion-dispersion relations (including Taylor-Aris-dispersion) as in classical convection-diffusion problems. Our results represent a systematic and efficient computational strategy to macroscopically track interfaces in heterogeneous media which together with the well-known versatility of phase field models forms a promising basis for the analysis of a wide spectrum of engineering and scientific applications such as oil recovery, for instance.

  7. Phase separation of binary mixtures in shear flow: A numerical study (United States)

    Corberi; Gonnella; Lamura


    The phase-separation kinetics of binary fluids in shear flow is studied numerically in the framework of the continuum convection-diffusion equation based on a Ginzburg-Landau free energy. Simulations are carried out for different temperatures both in d=2 and 3. Our results confirm the qualitative picture put forward by the large-N limit equations studied by Corberi et al. [Phys. Rev. Lett. 81, 3852 (1998)]. In particular, the structure factor is characterized by the presence of four peaks whose relative oscillations give rise to a periodic modulation of the behavior of the rheological indicators and of the average domains sizes. This peculiar pattern of the structure factor corresponds to the presence of domains with two characteristic thicknesses, whose relative abundance changes with time.

  8. Formation and phase separation during the smelting of sulfide raw materials (United States)

    Tarasov, A. V.; Paretsky, V. M.


    This paper discusses the most recent developments made at the Gintsvetmet Institute in technologies and equipment for single-stage autogenous smelting of copper sulfide raw materials to produce white metal and blister copper. In particular, the oxygen-flame smelting process and separation of highly basic calcium-containing slags are considered. This technology includes the oxygen-flame smelting process (KFP Process) to produce highly basic self-disintegrating ferrite-calcium slags with their subsequent flotation to recover copper. Also included is a sparging smelting process (FBP Process) to produce combined slags subjected to decopperizing inside the same furnace. Results of special investigations of the slag structure obtained in the KFP and FBP processes and substantiating selection of their chemical and phase composition are presented. These processes meet stringent requirements for advanced technologies with respect to energy conservation and environmental safety with different scales of production and within a wide range of specific conditions of particular operations.

  9. Tailorable Surface Morphology of 3D Scaffolds by Combining Additive Manufacturing with Thermally Induced Phase Separation. (United States)

    Di Luca, Andrea; de Wijn, Joost R; van Blitterswijk, Clemens A; Camarero-Espinosa, Sandra; Moroni, Lorenzo


    The functionalization of biomaterials substrates used for cell culture is gearing towards an increasing control over cell activity. Although a number of biomaterials have been successfully modified by different strategies to display tailored physical and chemical surface properties, it is still challenging to step from 2D substrates to 3D scaffolds with instructive surface properties for cell culture and tissue regeneration. In this study, additive manufacturing and thermally induced phase separation are combined to create 3D scaffolds with tunable surface morphology from polymer gels. Surface features vary depending on the gel concentration, the exchanging temperature, and the nonsolvent used. When preosteoblasts (MC-3T3 cells) are cultured on these scaffolds, a significant increase in alkaline phosphatase activity is measured for submicron surface topography, suggesting a potential role on early cell differentiation. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Hour-glass magnetic excitations induced by nanoscopic phase separation in cobalt oxides. (United States)

    Drees, Y; Li, Z W; Ricci, A; Rotter, M; Schmidt, W; Lamago, D; Sobolev, O; Rütt, U; Gutowski, O; Sprung, M; Piovano, A; Castellan, J P; Komarek, A C


    The magnetic excitations in the cuprate superconductors might be essential for an understanding of high-temperature superconductivity. In these cuprate superconductors the magnetic excitation spectrum resembles an hour-glass and certain resonant magnetic excitations within are believed to be connected to the pairing mechanism, which is corroborated by the observation of a universal linear scaling of superconducting gap and magnetic resonance energy. So far, charge stripes are widely believed to be involved in the physics of hour-glass spectra. Here we study an isostructural cobaltate that also exhibits an hour-glass magnetic spectrum. Instead of the expected charge stripe order we observe nano phase separation and unravel a microscopically split origin of hour-glass spectra on the nano scale pointing to a connection between the magnetic resonance peak and the spin gap originating in islands of the antiferromagnetic parent insulator. Our findings open new ways to theories of magnetic excitations and superconductivity in cuprate superconductors.

  11. Phase change in an opinion dynamics model with separation of time scales

    CERN Document Server

    Iñiguez, Gerardo; Kaski, Kimmo K; Barrio, R A


    We define an opinion formation model of agents in a 1d ring, where the opinion of an agent evolves due to its interactions with close neighbors and due to its either positive or negative attitude toward the overall mood of all the other agents. While the dynamics of the agent's opinion is described with an appropriate differential equation, from time to time pairs of agents are allowed to change their locations to improve the homogeneity of opinion (or comfort feeling) with respect to their short range environment. In this way the time scale of transaction dynamics and that of environment update are well separated and controlled by a single parameter. By varying this parameter we discovered a phase change in the number of undecided individuals. This phenomenon arises from the fact that too frequent location exchanges among agents result in frustration in their opinion formation. Our mean field analysis supports this picture.

  12. Killing by Type VI secretion drives genetic phase separation and correlates with increased cooperation (United States)

    McNally, Luke; Bernardy, Eryn; Thomas, Jacob; Kalziqi, Arben; Pentz, Jennifer; Brown, Sam P.; Hammer, Brian K.; Yunker, Peter J.; Ratcliff, William C.


    By nature of their small size, dense growth and frequent need for extracellular metabolism, microbes face persistent public goods dilemmas. Genetic assortment is the only general solution stabilizing cooperation, but all known mechanisms structuring microbial populations depend on the availability of free space, an often unrealistic constraint. Here we describe a class of self-organization that operates within densely packed bacterial populations. Through mathematical modelling and experiments with Vibrio cholerae, we show how killing adjacent competitors via the Type VI secretion system (T6SS) precipitates phase separation via the `Model A' universality class of order-disorder transition mediated by killing. We mathematically demonstrate that T6SS-mediated killing should favour the evolution of public goods cooperation, and empirically support this prediction using a phylogenetic comparative analysis. This work illustrates the twin role played by the T6SS, dealing death to local competitors while simultaneously creating conditions potentially favouring the evolution of cooperation with kin.

  13. Structure of silica xerogels synthesized with organoalkoxysilane co-reactants hints at multiple phase separation. (United States)

    Gommes, Cédric J; Basiura, Monika; Goderis, Bart; Pirard, Jean-Paul; Blacher, Silvia


    The microstructure of hybrid silica xerogels synthesized by the base-catalyzed polymerization of tetraethoxysilane (TEOS) in ethanol in the presence of 3-aminopropyltriethoxysilane (AES) and of 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS) as co-reactants, and dried in subcritical conditions, is analyzed. A thorough structural characterization of the samples is performed combining nitrogen adsorption, small-angle X-ray scattering (SAXS), and transmission electron microscopy coupled with digital image analysis. The use of these methods shows that, for both co-reactants, the xerogels are made of macropores supported by filaments, with each filament being formed of smaller structures. The quantitative impact of the additive on each structural level is assessed. The data are compared with a previous time-resolved SAXS study conducted during the formation of the gels (J. Phys. Chem. B 2004, 108, 8983-8991). The results are analyzed in the framework of a double phase separation model.

  14. Liquid-liquid transition without macroscopic phase separation in a water-glycerol mixture (United States)

    Murata, Ken-Ichiro; Tanaka, Hajime


    The existence of more than two liquid states in a single-component substance and the ensuing liquid-liquid transitions (LLTs) has attracted considerable attention because of its counterintuitive nature and its importance in the fundamental understanding of the liquid state. Here we report direct experimental evidence for a genuine (isocompositional) LLT without macroscopic phase separation in an aqueous solution of glycerol. We show that liquid I transforms into liquid II by way of two types of kinetics: nucleation and growth, and spinodal decomposition. Although liquid II is metastable against crystallization, we could access both its static and dynamical properties experimentally. We find that liquids I and II differ in density, refractive index, structure, hydrogen bonding state, glass transition temperature and fragility, and that the transition between the two liquids is mainly driven by the local structuring of water rather than of glycerol, suggesting a link to a plausible LLT inpure water.

  15. Thermodynamic stability of driven open systems and control of phase separation by electro-autocatalysis. (United States)

    Bazant, Martin Z


    Motivated by the possibility of electrochemical control of phase separation, a variational theory of thermodynamic stability is developed for driven reactive mixtures, based on a nonlinear generalization of the Cahn-Hilliard and Allen-Cahn equations. The Glansdorff-Prigogine stability criterion is extended for driving chemical work, based on variations of nonequilibrium Gibbs free energy. Linear stability is generally determined by the competition of chemical diffusion and driven autocatalysis. Novel features arise for electrochemical systems, related to controlled total current (galvanostatic operation), concentration-dependent exchange current (Butler-Volmer kinetics), and negative differential reaction resistance (Marcus kinetics). The theory shows how spinodal decomposition can be controlled by solo-autocatalytic charge transfer, with only a single faradaic reaction. Experimental evidence is presented for intercalation and electrodeposition in rechargeable batteries, and further applications are discussed in solid state ionics, electrovariable optics, electrochemical precipitation, and biological pattern formation.

  16. Separation of nonionic compounds by electrokinetic chromatography using an inorganic layered compound as a pseudostationary phase. (United States)

    Koike, Ryo; Kitagawa, Fumihiko; Otsuka, Koji


    The use of an inorganic layered compound as a pseudostationary phase (PSP) in EKC was investigated. A synthetic smectite, which is the most typical swellable clay mineral, with an average diameter of 130 nm was selected as the PSP. The retention characteristics of the smectite and on-line sample concentration by sweeping were examined for the analysis of polyoxyethylene mono phenyl ethers (PPEs) with different degrees of ethoxylation. The retention factor was increased with increase in the number of ethylene oxide groups and a good separation of the PPE homologs was achieved by smectite-EKC. The RSD of the migration time, plate number, and peak area were 0.60, 8.3, and 2.7% (n = 5), respectively. The developed method can be applied to the analysis of PPEs in commercially available consumer products without any sample pretreatments. In addition, ca. 100-fold sensitivity enhancements for the PPEs with high retention factors were obtained by sweeping.

  17. Characterization of Polysulfone Membranes Prepared with Thermally Induced Phase Separation Technique (United States)

    Tiron, L. G.; Pintilie, Ș C.; Vlad, M.; Birsan, I. G.; Baltă, Ș


    Abstract Membrane technology is one of the most used water treatment technology because of its high removal efficiency and cost effectiveness. Preparation techniques for polymer membranes show an important aspect of membrane properties. Generally, polysulfone (PSf) and polyethersulfone (PES) are used for the preparation of ultrafiltration (UF) membranes. Polysulfone (PSf) membranes have been widely used for separation and purification of different solutions because of their excellent chemical and thermal stability. Polymeric membranes were obtained by phase inversion method. The polymer solution introduced in the nonsolvent bath (distilled water) initiate the evaporation of the solvent from the solution, this phenomenon has a strong influence on the transport properties. The effect of the coagulation bath temperature on the membrane properties is of interest for this study. Membranes are characterized by pure water flux, permeability, porosity and retention of methylene blue. The low temperature of coagulation bath improve the membrane’s rejection and its influence was most notable.

  18. Flow-parametric regulation of shear-driven phase separation in two and three dimensions

    CERN Document Server

    O'Naraigh, Lennon; Naso, Aurore


    The Cahn--Hilliard equation with an externally-prescribed chaotic shear flow is studied in two and three dimensions. The flow is parametrized by its amplitudes (thereby admitting the possibility of anisotropy), lengthscales, and multiple time scales. Two key features emerge. First, for long flow correlation times, large flow amplitudes and small Cahn--Hilliard diffusivities, the phase separation and the associated coarsening phenomenon are not only arrested but in fact the concentration variance decays, thereby opening up the possibility of describing the dynamics of the concentration field using the theories of advection diffusion. Secondly, for anisotropic scenarios wherein the variance saturates, the direction in which the domains align depends on the flow correlation time. Thus, for correlation times comparable to the inverse of the mean shear rate, the domains align in the direction of maximum flow amplitude, while for short correlation times, the domains initially align in the opposite direction. Howeve...

  19. Phase separation and interface structure in two dimensions from field theory

    CERN Document Server

    Delfino, Gesualdo


    We study phase separation in two dimensions in the scaling limit below criticality. The general form of the magnetization profile as the volume goes to infinity is determined exactly within the field theoretical framework which explicitly takes into account the topological nature of the elementary excitations. The result known for the Ising model from its lattice solution is recovered as a particular case. In the asymptotic infrared limit the interface behaves as a simple curve characterized by a gaussian passage probability density. The leading deviation, due to branching, from this behavior is also derived in general and its coefficient is determined for the Potts model. As a byproduct, for random percolation we obtain the asymptotic density profile of a spanning cluster conditioned to touch only the left half of the boundary.

  20. Strategies towards controlling strain-induced mesoscopic phase separation in manganite thin films (United States)

    Habermeier, H.-U.


    Complex oxides represent a class of materials with a plethora of fascinating intrinsic physical functionalities. The intriguing interplay of charge, spin and orbital ordering in these systems superimposed by lattice effects opens a scientifically rewarding playground for both fundamental as well as application oriented research. The existence of nanoscale electronic phase separation in correlated complex oxides is one of the areas in this field whose impact on the current understanding of their physics and potential applications is not yet clear. In this paper this issue is treated from the point of view of complex oxide thin film technology. Commenting on aspects of complex oxide thin film growth gives an insight into the complexity of a reliable thin film technology for these materials. Exploring fundamentals of interfacial strain generation and strain accommodation paves the way to intentionally manipulate thin film properties. Furthermore, examples are given for an extrinsic continuous tuning of intrinsic electronic inhomogeneities in perovskite-type complex oxide thin films.

  1. Synthesis and characterization of novel stationary phases for small scale liquid chromatographic separations of proteins and nanoparticles (United States)

    Hutanu, Daniela

    The emerging field of nanotechnology strictly requires the micro-scaling of the available separation technology and the design of novel devices for separations of molecules of interest. The separation of proteins and nanoparticles is challenging due to their relatively large size, non-specific adherence to surfaces and instability in many solvents. This dissertation presents the synthesis and characterization of novel stationary phases for use in separations of proteins or nanoparticles in both capillary and microchip formats. In order to separate blood proteins with high specificity, a DNA aptamer selected for alpha-thrombin was employed as an affinity component of the stationary phases. Silica surfaces and organic monoliths were modified with the aptamer via an azlactone linkage and have demonstrated highly efficient separations of thrombin from a mixture in the microscale. The high efficiency of the protein separation (HETP = 276 mum, RS = 1.7) is comparable with macroscale results using antibodies as the affinity factor. Novel hybrid inorganic-organic polysilsesquioxane stationary phases were synthesized by way of surfactant templated polymerization of bridged alcoxy-silyl ethane monomers, in presence of sodium hydroxide. The novel materials were successful in size exclusion separation of polystyrene standards with molecular diameters of 0.3-2.4 nm. A hybrid inorganic-organic polysilsesquioxane sorbent also proved useful for small scale separations of triphenyl phosphine protected gold nanoparticles, based on a sorptive mechanism instead of a size exclusion mechanism. Polysilsesquioxanes were easily synthesized in-situ inside fused silica capillary columns and PMMA microchip channels in order to facilitate integration with a micro-reactor. The novel stationary phases proved efficient for separation of proteins and nanoparticles in the micro-scale format and can further be utilized for online purification and separation of these difficult compounds.

  2. Effects of Phase Separation Behavior on Morphology and Performance of Polycarbonate Membranes

    Directory of Open Access Journals (Sweden)

    Alamin Idris


    Full Text Available The phase separation behavior of bisphenol-A-polycarbonate (PC, dissolved in N-methyl-2-pyrrolidone and dichloromethane solvents in coagulant water, was studied by the cloud point method. The respective cloud point data were determined by titration against water at room temperature and the characteristic binodal curves for the ternary systems were plotted. Further, the physical properties such as viscosity, refractive index, and density of the solution were measured. The critical polymer concentrations were determined from the viscosity measurements. PC/NMP and PC/DCM membranes were fabricated by the dry-wet phase inversion technique and characterized for their morphology, structure, and thermal stability using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis, respectively. The membranes’ performances were tested for their permeance to CO2, CH4, and N2 gases at 24 ± 0.5 °C with varying feed pressures from 2 to 10 bar. The PC/DCM membranes appeared to be asymmetric dense membrane types with appreciable thermal stability, whereas the PC/NMP membranes were observed to be asymmetric with porous structures exhibiting 4.18% and 9.17% decrease in the initial and maximum degradation temperatures, respectively. The ideal CO2/N2 and CO2/CH4 selectivities of the PC/NMP membrane decreased with the increase in feed pressures, while for the PC/DCM membrane, the average ideal CO2/N2 and CO2/CH4 selectivities were found to be 25.1 ± 0.8 and 21.1 ± 0.6, respectively. Therefore, the PC/DCM membranes with dense morphologies are appropriate for gas separation applications.

  3. A Phase-Locked Loop with 30% Jitter Reduction Using Separate Regulators

    Directory of Open Access Journals (Sweden)

    Tzung-Je Lee


    Full Text Available A phase-locked loop (PLL using separate regulators to reject the supply noise is proposed in this paper. Two regulators, REG1 and REG2, are used to prevent the supply noise from the charge pump (CP and the voltage-controlled oscillator (VCO, respectively. By using separate regulators, the area and the power consumption of the regulator can be reduced. Moreover, the jitter of the proposed PLL is proven on silicon to be less sensitive to the supply noise. The proposed PLL is fabricated using a typical 0.35 μm 2P4M CMOS process. The peak-to-peak jitter (P2P jitter of the proposed PLL is measured to be 81.8 ps at 80 MHz when a 250 mVrms supply noise is added. By contrast, the P2P jitter is measured to be 118.2 ps without the two regulators when the same supply noise is coupled.

  4. Analysis of Protein Glycosylation and Phosphorylation Using Liquid Phase Separation, Protein Microarray Technology, and Mass Spectrometry (United States)

    Zhao, Jia; Patwa, Tasneem H.; Pal, Manoj; Qiu, Weilian; Lubman, David M.


    Summary Protein glycosylation and phosphorylation are very common posttranslational modifications. The alteration of these modifications in cancer cells is closely related to the onset and progression of cancer and other disease states. In this protocol, strategies for monitoring the changes in protein glycosylation and phosphorylation in serum or tissue cells on a global scale and specifically characterizing these alterations are included. The technique is based on lectin affinity enrichment for glycoproteins, all liquid-phase two-dimensional fractionation, protein microarray, and mass spectrometry technology. Proteins are separated based on pI in the first dimension using chromatofocusing (CF) or liquid isoelectric focusing (IEF) followed by the second-dimension separation using nonporous silica RP-HPLC. Five lectins with different binding specificities to glycan structures are used for screening glycosylation patterns in human serum through a biotin–streptavidin system. Fluorescent phosphodyes and phosphospecific antibodies are employed to detect specific phosphorylated proteins in cell lines or human tissues. The purified proteins of interest are identified by peptide sequencing. Their modifications including glycosylation and phosphorylation could be further characterized by mass-spectrometry-based approaches. These strategies can be used in biological samples for large-scale glycoproteome/phosphoproteome screening as well as for individual protein modification analysis. PMID:19241043

  5. Separation of bacteriochlorophyll homologues from green photosynthetic sulfur bacteria by reversed-phase HPLC. (United States)

    Borrego, C M; Garcia-Gil, L J


    A reversed-phase High Performance Liquid Cromatography (HPLC) method has been developed to accurately separate bacteriochlorophyllsc, d ande homologues in a reasonably short run time of 60 minutes. By using this method, two well-defined groups of bacteriochlorophyll homologue peaks can be discriminated. The first one consists of 4 peaks (min 24 to 30), which corresponds to the four main farnesyl homologues. The second peak subset is formed by a cluster of up to 10 minor peaks (min 33 to 40). These peaks can be related with series of several alcohol esters of the different chlorosome chlorophylls. The number of homologues was, however, quite variable depending on both, the bacteriochlorophyll and the bacterial species. The method hereby described, also provides a good separation of other photosynthetic pigments, either bacterial (Bacteriochlorophylla, chlorobactene, isorenieratene and okenone) or algal ones (Chlorophylla, Pheophytina and β-carotene). A preliminary screening of the homologue composition of several green photosynthetic bacterial species and isolates, has revealed different relative quantitative patterns. These differences seem to be related to physiological aspects rather than to taxonomic ones. The application of the method to the study of natural populations avoids the typical drawbacks on the pigment identification of overlapping eukaryotic and prokaryotic phototrophic microorganisms, giving further information about their physiological status.

  6. New caffeine bonded phase for separation of polyaromatic hydrocarbons and petroleum asphaltenes by high-performance liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Felix, G.; Bertrand, C.; Gastel, F. van


    The preparation of a new caffeine phase for HPLC is described. The capacity ratios (k') of about ten polyaromatic hydrocarbons have been determined. It has been shown that the aromatics were eluted according the number of rings, only slightly influenced by the substituents. The performance of the stationary phase is demonstrated with separations of petroleum asphalts and residues and aromatic mixtures.

  7. Development of separation technology for the removal of radium-223 from decayed thorium-227 in drug formulations. Material screening and method development. (United States)

    Frenvik, Janne Olsen; Kristensen, Solveig; Ryan, Olav B


    Targeted thorium conjugates are currently being investigated as a new class of alpha-radiopharmaceuticals. The natural decay of thorium-227 ((227)Th) results in the ingrowth of radium-223 ((223)Ra). Consideration must, therefore, be given to define acceptable limits of (223)Ra in the drug product at the time of dose administration. By effective sequestration of (223)Ra, we aim to improve the radiochemical purity and extend the effective user window of drug products containing (227)Th. (223)Ra is the first progeny of (227)Th and the only one with a long half-life (days). We have, therefore, focused on the removal of this specific species since the progenies of (223)Ra will have a very limited lifetime in the formulation once (223)Ra is removed. In this study, we investigated a multitude of materials for their ability to reduce the (223)Ra level by: (1) passive diffusion or (2) by cartridge filtration on gravity columns. In addition, we probe the compatibility of these materials in the presence of antibody trastuzumab to assess the level of protein binding and estimate the quenching of radiolysis by binding of radionuclides. A screening matrix of organic and inorganic materials was established, i.e. strontium and calcium alginate gel beads, distearoyl phosphatidylglycerol (DSPG) liposomes, ceramic hydroxyapatite, Zeolite UOP type 4A and cation exchange resins AG50W-X8 and SOURCE 30S. First, passive diffusional uptake of (223)Ra by suspended materials present in the formulation was measured as a decrease in sample radioactivity after separation. Second, selected materials were packed on gravity columns in order to evaluate the efficiency of column separation versus diffusional adsorption. The retention of (223)Ra and (227)Th were characterized by measuring the radioactivity in the eluate and on the columns. Finally, the compatibility between trastuzumab, as a selected model antibody, and suspensions of the binding materials was analyzed during storage of the drug

  8. Phase 1 trial of malaria transmission blocking vaccine candidates Pfs25 and Pvs25 formulated with montanide ISA 51.

    Directory of Open Access Journals (Sweden)

    Yimin Wu

    Full Text Available BACKGROUND: Pfs25 and Pvs25, surface proteins of mosquito stage of the malaria parasites P. falciparum and P. vivax, respectively, are leading candidates for vaccines preventing malaria transmission by mosquitoes. This single blinded, dose escalating, controlled Phase 1 study assessed the safety and immunogenicity of recombinant Pfs25 and Pvs25 formulated with Montanide ISA 51, a water-in-oil emulsion. METHODOLOGY/PRINCIPAL FINDINGS: The trial was conducted at The Johns Hopkins Center for Immunization Research, Washington DC, USA, between May 16, 2005-April 30, 2007. The trial was designed to enroll 72 healthy male and non-pregnant female volunteers into 1 group to receive adjuvant control and 6 groups to receive escalating doses of the vaccines. Due to unexpected reactogenicity, the vaccination was halted and only 36 volunteers were enrolled into 4 groups: 3 groups of 10 volunteers each were immunized with 5 microg of Pfs25/ISA 51, 5 microg of Pvs25/ISA 51, or 20 microg of Pvs25/ISA 51, respectively. A fourth group of 6 volunteers received adjuvant control (PBS/ISA 51. Frequent local reactogenicity was observed. Systemic adverse events included two cases of erythema nodosum considered to be probably related to the combination of the antigen and the adjuvant. Significant antibody responses were detected in volunteers who completed the lowest scheduled doses of Pfs25/ISA 51. Serum anti-Pfs25 levels correlated with transmission blocking activity. CONCLUSION/SIGNIFICANCE: It is feasible to induce transmission blocking immunity in humans using the Pfs25/ISA 51 vaccine, but these vaccines are unexpectedly reactogenic for further development. This is the first report that the formulation is associated with systemic adverse events including erythema nodosum. TRIAL REGISTRATION: NCT00295581.

  9. Developing methodologies for source attribution. Glass phase separation in Trinitite using NF{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Koeman, Elizabeth C.; Simonetti, Antonio [Notre Dame Univ., IN (United States). Dept. of Civil and Environmental Engineering and Earth Sciences; McNamara, Bruce K.; Smith, Frances N. [Pacific Northwest National Laboratory, Richland, WA (United States). Nuclear Chemistry and Engineering; Burns, Peter C. [Notre Dame Univ., IN (United States). Dept. of Civil and Environmental Engineering and Earth Sciences; Notre Dame Univ., IN (United States). Dept. of Chemistry and Biochemistry


    This study details thermal reactions between glasses, common minerals, and Trinitite post-detonation material with the fluorinating agent nitrogen trifluoride (NF{sub 3}). The ultimate goal of our investigation is to develop a relatively rapid method for the effective separation of bomb components from complex matrices resulting from a nuclear explosion. Trinitite samples, silicate minerals (quartz; plagioclase and microcline), amorphous SiO{sub 2}, calcite, a natural glass (obsidian), and two synthetic glasses were characterized extensively before and after the fluorination to fully understand the effects of the NF{sub 3} thermal treatment. Samples were reacted with NF{sub 3} using a combined thermogravimetric (TG) differential thermal analysis (DTA) unit, as well as in a stainless steel bomb reactor connected to a fluorination line. Subsequent to the NF{sub 3} treatment, samples were imaged by scanning electron microscopy in order to document changes in grain size and morphology. Energy dispersive spectroscopy was performed to determine changes in major element abundances. Results demonstrate that rates of reaction are dependent on grain size, temperature, pressure, and time of fluorination. All mineral samples experienced mass loss during fluorination. Specifically, amorphous SiO{sub 2} (∝90% mass loss) experienced the most while calcite experienced the least (∝18%). Major element analysis reveals that mass loss is attributable to the volatilization of silica (SiO{sub 2}) in Si-bearing phases, or sample decomposition in calcite due to fluorination. Results for fluorinated samples of Trinitite demonstrate that mass loss occurs at different rates for each sample, but each sample experienced an expected large decrease in Si content (resulting from volatilization of SiF{sub 4}). Hence, the concentration of metals in the residual material increased due to the volatilization of Si. These results validate that this thermal-fluorination technique allows the

  10. Enzymatic hydrolysis of penicillin and in situ product separation in thermally induced reversible phase-separation of ionic liquids/water mixture. (United States)

    Mai, Ngoc Lan; Koo, Yoon-Mo


    Enzymatic hydrolysis of penicillin G to produce 6-aminopenicillanic acid, key intermediate for the production of semisynthetic β-lactam antibiotics, is one of the most relevant example of industrial implementation of biocatalysts. The hydrolysis reaction is traditionally carried out in aqueous buffer at pH 7.5-8. However, the aqueous rout exhibits several drawbacks in enzyme stability and product recovery. In this study, several ionic liquids (ILs) have been used as media for enzymatic hydrolysis of penicillin G. The results indicated that hydrophobic ILs/water two-phase system were good media for the reaction. In addition, a novel aqueous two-phase system based on the lower critical solution temperature type phase changes of amino acid based ILs/water mixture was developed for in situ penicillin G hydrolysis and product separation. For instance, hydrolysis yield of 87.13% was obtained in system containing 30 wt% [TBP][Tf-ILe] with pH control (pH 7.6). Since the phase-separation of this medium system can be reversible switched from single to two phases by slightly changing the solution temperature, enzymatic hydrolytic reaction and product recovery were more efficient than those of aqueous system. In addition, the ILs could be reused for at least 5 cycles without significant loss in hydrolysis efficiency.

  11. Phase separation between nucleoid and cytoplasm in Escherichia coli as defined by immersive refractometry. (United States)

    Valkenburg, J A; Woldringh, C L


    The refractive indices of nucleoid and cytoplasm in Escherichia coli were derived theoretically and experimentally. For the theoretical estimates, we made use of the known macromolecular composition of E. coli B/r (G. Churchward and H. Bremer, J. Theor. Biol. 94:651-670, 1982) and of estimates of cell and nucleoid volumes. These were obtained from micrographs of living bacteria made with a confocal scanning light microscope. The theoretical values were calculated, assuming that all DNA occurred in the nucleoid and that all protein and RNA occurred in the cytoplasm. Comparison with experimental refractive index values directly obtained by immersive refractometry showed that, besides its DNA, the nucleoid must contain an additional amount of solids equivalent to 8.6% (wt/vol) protein. With the nucleoid containing 6.8% (wt/vol) DNA and 8.6% (wt/vol) protein and the cytoplasm containing 21% (wt/vol) protein and 4% (wt/vol) RNA, a mass difference is obtained, which accounts for the phase separation observed between the nucleoid and cytoplasm in living cells by phase-contrast microscopy. The decrease in the refractive index of the nucleoid relative to that of the cytoplasm observed upon, for instance, OsO4 fixation was interpreted as being indicative of the loss of protein content in the nucleoid. Images PMID:6389508

  12. Combining mechanical foaming and thermally induced phase separation to generate chitosan scaffolds for soft tissue engineering. (United States)

    Biswas, D P; Tran, P A; Tallon, C; O'Connor, A J


    In this paper, a novel foaming methodology consisting of turbulent mixing and thermally induced phase separation (TIPS) was used to generate scaffolds for tissue engineering. Air bubbles were mechanically introduced into a chitosan solution which forms the continuous polymer/liquid phase in the foam created. The air bubbles entrained in the foam act as a template for the macroporous architecture of the final scaffolds. Wet foams were crosslinked via glutaraldehyde and frozen at -20 °C to induce TIPS in order to limit film drainage, bubble coalescence and Ostwald ripening. The effects of production parameters, including mixing speed, surfactant concentration and chitosan concentration, on foaming are explored. Using this method, hydrogel scaffolds were successfully produced with up to 80% porosity, average pore sizes of 120 μm and readily tuneable compressive modulus in the range of 2.6 to 25 kPa relevant to soft tissue engineering applications. These scaffolds supported 3T3 fibroblast cell proliferation and penetration and therefore show significant potential for application in soft tissue engineering.

  13. Dissolved carbon dioxide flotation: an effective way for phase separation in emulsification microextraction method. (United States)

    Molaei, Saeideh; Saleh, Abolfazl; Ghoulipour, Vanik; Seidi, Shahram


    Dissolved carbon dioxide flotation after emulsification microextraction (DCF-EME) technique coupled with gas chromatography-electron capture detection (GC-ECD) was introduced for preconcentration and determination of six organochlorine pesticides (OCPs) in seawater samples. DCF-EME method is based on the rapid and simple phase separation of low density organic solvent from the aqueous phase via introducing of a saturated NaHCO3 solution (9.6% w/v) into the acidified sample solution (0.1M of HCl) containing analytes. Thanks to the in situ generation of carbon dioxide (CO2) bobbles intensified by ultrasound radiation, the dispersed extraction solvent was collected to the surface of the aqueous sample and then was narrowed to the capillary part of a special home-made extraction cell for facile retrieving. Under the optimal conditions, the limits of detection were at the range of 2.6-9.2 ng L(-1) and preconcentration factors were varied between 271 and 307 for different OCPs. The applicability of the developed method was evaluated by the extraction and determination of the target analytes from Caspian seawater samples.

  14. Solution processing of polymer semiconductor: Insulator blends-Tailored optical properties through liquid-liquid phase separation control

    KAUST Repository

    Hellmann, Christoph


    © 2014 Wiley Periodicals, Inc. It has been demonstrated that the 0-0 absorption transition of poly(3-hexylthiophene) (P3HT) in blends with poly(ethylene oxide) (PEO) could be rationally tuned through the control of the liquid-liquid phase separation process during solution deposition. Pronounced J-like aggregation behavior, characteristic for systems of a low exciton band width, was found for blends where the most pronounced liquid-liquid phase separation occurred in solution, leading to domains of P3HT and PEO of high phase purity. Since liquid-liquid phase separation could be readily manipulated either by the solution temperature, solute concentration, or deposition temperature, to name a few parameters, our findings promise the design from the out-set of semiconductor:insulator architectures of pre-defined properties by manipulation of the interaction parameter between the solutes as well as the respective solute:solvent system using classical polymer science principles.

  15. Heat and mass transfer in porous media phase separation at temperatures below the lambda-point of He-4 (United States)

    Yuan, S. W. K.; Frederking, T. H. K.


    Newtonian fluid motion, coupled to heat transfer via latent heat of phase transition, is well known from numerous studies of condensation and boiling. Considerably less knowledge is available for vapor-liquid phase separation in the absence of gravity effect on the transport phenomena. The present studies are focused on heat and mass transfer associated with vapor-liquid phase separation required for long-term storage of the cryogen liquid He II in space vessels. Though space conditions are the dominant mode of interest in advanced equipment, e.g. IR telescopes, the systems may be operated in principle during terrestrial conditions. The latter are considered in the present work. It emphasizes the linear regime including an extrapolation based on variable thermophysical properties. Data taken with a phase separation approach show departures from the linear regime prediction. They agree with a transport equation proposed for the nonlinear, turbulent regime.

  16. Heat and mass transfer in porous media phase separation at temperatures below the lambda-point of He-4 (United States)

    Yuan, S. W. K.; Frederking, T. H. K.


    Newtonian fluid motion, coupled to heat transfer via latent heat of phase transition, is well known from numerous studies of condensation and boiling. Considerably less knowledge is available for vapor-liquid phase separation in the absence of gravity effect on the transport phenomena. The present studies are focused on heat and mass transfer associated with vapor-liquid phase separation required for long-term storage of the cryogen liquid He II in space vessels. Though space conditions are the dominant mode of interest in advanced equipment, e.g. IR telescopes, the systems may be operated in principle during terrestrial conditions. The latter are considered in the present work. It emphasizes the linear regime including an extrapolation based on variable thermophysical properties. Data taken with a phase separation approach show departures from the linear regime prediction. They agree with a transport equation proposed for the nonlinear, turbulent regime.

  17. Effect of Partition of Photo-Initiator Components and Addition of Iodonium Salt on the Photopolymerization of Phase-Separated Dental Adhesive (United States)

    Abedin, Farhana; Ye, Qiang; Song, Linyong; Ge, Xueping; Camarda, Kyle; Spencer, Paulette


    The polymerization kinetics of physically separated hydrophobic- and hydrophilic-rich phases of a model dental adhesive have been investigated. The two phases were prepared from neat resin containing 2-hydroxyethyl methacrylate and bisphenol A glycerolate dimethacrylate (BisGMA) in the ratio of 45:55 (wt./wt.). Neat resins containing various combinations of popular photo-initiating compounds, e.g., camphoquinone (CQ), ethyl 4-(dimethylamino)benzoate (EDMAB), 2-(dimethylamino)ethyl methacrylate (DMAEMA), and diphenyliodonium hexafluorophosphate (DPIHP), were prepared. To obtain the two phases, 33 wt.% of deuterium oxide (D2O) was added to the neat resins. This amount of D2O exceeded the miscibility limit for the resins. The concentration of each component of the photo-initiating system in the two phases was quantified by high-performance liquid chromatography (HPLC). When combined with CQ, DMAEMA is less efficient as a co-initiator compared to EDMAB. The addition of DPIHP as the third component into either CQ/EDMAB or CQ/DMAEMA photo-initiating systems led to comparable performance in both the hydrophobic- and hydrophilic-rich phases. The addition of the iodonium salt significantly improved the photopolymerization of the hydrophilic-rich phase; the latter exhibited extremely poor polymerization when the iodonium salt was not included in the formulation. The partition concentration of EDMAB in the hydrophilic-rich phase was significantly lower than that of DMAEMA or DPIHP. This study indicates the need for a combination of hydrophobic/hydrophilic photosensitizer and addition of iodonium salt to improve polymerization within the hydrophilic-rich phase of the dental adhesive.

  18. Triton X-114 phase separation in the isolation and purification of mouse liver microsomal membrane proteins. (United States)

    Mathias, Rommel A; Chen, Yuan-Shou; Kapp, Eugene A; Greening, David W; Mathivanan, Suresh; Simpson, Richard J


    Integral membrane proteins (IMPs) mediate several cellular functions including cell adhesion, ion and nutrient transport, and cell signalling. IMPs are typically hard to isolate and purify due to their hydrophobic nature and low cellular abundance, however, microsomes are small lipid vesicles rich in IMPs, which form spontaneously when cells are mechanically disrupted. In this study, we have employed mouse liver microsomes as a model for optimising a method for IMP isolation and characterisation. Microsomes were collected by differential centrifugation, purified with sodium carbonate, and subjected to GeLC-MS/MS analysis. A total of 1124 proteins were identified in the microsome fraction, with 47% (524/1124) predicted by TMHMM to contain at least one transmembrane domain (TMD). The ability of phase partitioning using the detergent Triton X-114 (TX-114) to further enrich for membrane proteins was evaluated. Microsomes were subjected to successive rounds of solubility-based phase separation, with proteins partitioning into the aqueous phase, detergent phase, or TX-114-insoluble pellet fraction. GeLC-MS/MS analysis of the three TX-114 fractions identified 1212 proteins, of which 146 were not detected in the un-fractionated microsome sample. Conspicuously, IMPs partitioned to the detergent phase, with 56% (435/770) of proteins identified in that fraction containing at least one TMD. GO Slim characterisation of the microsome proteome revealed enrichment of proteins from the endoplasmic reticulum, mitochondria, Golgi apparatus, endosome, and cytoplasm. Further, enzymes including monooxygenases were well represented with 35 cytochrome P450 identifications (CYPs 1A2, 2A5, 2A12, 2B10, 2C29, 2C37, 2C39, 2C44, 2C50, 2C54. 2C67, 2C68, 2C70, 2D10, 2D11, 2D22, 2D26, 2D9, 2E1, 2F2, 2J5, 2U1, 3A11, 3A13, 3A25, 4A10, 4A12A, 4A12B, 4F13, 4F14, 4F15, 4V3, 51,7B1, and 8B1). Evaluation of biological processes showed enrichment of proteins involved in fatty acid biosynthesis and

  19. Novel Gas-assisted Three-liquid-phase Extraction System for Simultaneous Separation and Concentration of Anthraquinones in Herbal Extract

    Institute of Scientific and Technical Information of China (English)

    Xingfu Yang; Xiangfeng Liang; Liangrong Yang; Feng Pan; Fuli Deng; Huizhou Liu


    abstract Gas-assisted three-liquid-phase extraction (GATE), which has the advantages of both three-liquid-phase extrac-tion and solvent sublation, is a novel separation technique for separation and concentration of two organic com-pounds into different phases in one step. This highly effective and economically applicable method has been developed for separating emodin and rhein from herbal extract. In a GATE system composed of butyl acetate/PEG4000/ammonium sulfate aqueous solution, influence of various parameters including gas flow rate, flotation time, salt concentration, initial volume of PEG and butyl acetate was investigated. Within 50 min of 30 ml·min-1 nitrogen flow, removal ratio of emodin and rhein from aqueous phase could be over 99%and 97%, respectively. Mass fraction of emodin in the BA phase and rhein in the PEG phase could reach 97%and 95%, respectively. It is demonstrated that gas bubbling is effective for partitioning of emodin and rhein into butyl acetate and PEG phase respectively, and dispersed PEG and butyl acetate could be captured from the aqueous solution. Experi-mental results show that GATE could be an effective and economical technology for concentration and separation of co-existed products in medicinal plants.

  20. The separation of peptide hormone diastereoisomers by reverse phase high pressure liquid chromatography. Factors affecting separation of oxytocin and its diastereoisomers--structural implications. (United States)

    Larsen, B; Fox, B L; Burke, M F; Hruby, V J


    Experimental conditions and parameters involved in high performance liquid chromatography (HPLC) separations of the peptide hormone oxytocin and seven of its diastereoisomers, namely [1-hemi-D-cystine]-, [2-D-tyrosine]-, [4-D-glutamine]-, [5-D-asparagine]-, [6-hemi-D-cystine-], [7-D-proline]-, and [8-D-leucine]-oxytocin, on reverse phase columns were investigated. The effects of solvent, pH, and salt concentration were studied. Using the solvent systems 10% tetrahydrofuran-ammonium acetate buffer or 18% acetonitrile-ammonium acetate buffer and the muBondapak C18 support, oxytocin was separated from each of its diastereoisomers under all conditions studied, but the order of elution of diastereoisomers was highly dependent on solvent and to a lesser extent on pH. Separations of the hormone and its diastereoisomers on reverse phase HPLC and on classical partition chromatography on Sephadex G-25 were compared. The results are discussed in terms of the interactions of the solute with the reverse phase column and the solvent system. Implications of these findings in terms of the different solution conformations of the peptides are discussed.

  1. A generalized volumetric dispersion model for a class of two-phase separation/reaction: finite difference solutions (United States)

    Siripatana, Chairat; Thongpan, Hathaikarn; Promraksa, Arwut


    This article explores a volumetric approach in formulating differential equations for a class of engineering flow problems involving component transfer within or between two phases. In contrast to conventional formulation which is based on linear velocities, this work proposed a slightly different approach based on volumetric flow-rate which is essentially constant in many industrial processes. In effect, many multi-dimensional flow problems found industrially can be simplified into multi-component or multi-phase but one-dimensional flow problems. The formulation is largely generic, covering counter-current, concurrent or batch, fixed and fluidized bed arrangement. It was also intended to use for start-up, shut-down, control and steady state simulation. Since many realistic and industrial operation are dynamic with variable velocity and porosity in relation to position, analytical solutions are rare and limited to only very simple cases. Thus we also provide a numerical solution using Crank-Nicolson finite difference scheme. This solution is inherently stable as tested against a few cases published in the literature. However, it is anticipated that, for unconfined flow or non-constant flow-rate, traditional formulation should be applied.

  2. Improving gas separation properties of polymeric membranes based on glassy polymers by gas phase fluorination

    NARCIS (Netherlands)

    Syrtsova, D.A.; Kharitonov, A.P.; Teplyakov, V.V.; Koops, G.-H.


    The application area of existing gas separation membranes is limited by commercially available polymers for their preparation. In many cases the separation selectivity of these polymers is not sufficient for effective separation processes. One of the ways to improve the separation effectivity of exi

  3. Comparison of analytical protein separation characteristics for three amine-based capillary-channeled polymer (C-CP) stationary phases. (United States)

    Jiang, Liuwei; Marcus, R Kenneth


    Capillary-channeled polymer (C-CP) fiber stationary phases are finding utility in the realms of protein analytics as well as downstream processing. We have recently described the modification of poly(ethylene terephthalate) (PET) C-CP fibers to affect amine-rich phases for the weak anion-exchange (WAX) separation of proteins. Polyethylenimine (PEI) is covalently coupled to the PET surface, with subsequent cross-linking imparted by treatment with 1,4-butanediol diglycidyl ether (BUDGE). These modifications yield vastly improved dynamic binding capacities over the unmodified fibers. We have also previously employed native (unmodified) nylon 6 C-CP fibers as weak anion/cation-exchange (mixed-mode) and hydrophobic interaction chromatography (HIC) phases for protein separations. Polyamide, nylon 6, consists of amide groups along the polymer backbone, with primary amines and carboxylic acid end groups. The analytical separation characteristics of these three amine-based C-CP fiber phases are compared here. Each of the C-CP fiber columns in this study was shown to be able to separate a bovine serum albumin/hemoglobin/lysozyme mixture at high mobile phase linear velocity (∼70 mm s(-1)) but with different elution characteristics. These differences reflect the types of protein-surface interactions that are occurring, based on the active group composition of the fiber surfaces. This study provides important fundamental understanding for the development of surface-modified C-CP fiber columns for protein separation.

  4. High performance liquid chromatographic separation of eight drugs collected in Chinese Pharmacopoeia 2010 on amylose ramification chiral stationary phase

    Directory of Open Access Journals (Sweden)

    Yan Wang


    Full Text Available The enantiomers separation of eight pharmaceutical racemates collected in Chinese Pharmacopoeia 2010 (Ch.P2010, including nitrendipine, felodipine, omeprazole, praziquantel, sulpiride, clenbuterol hydrochloride, verapamil hydrochloride and chlorphenamine maleate, was performed on chiral stationary phase of amylose ramification by high performance liquid chromatography (HPLC on Chiralpak AD-H column and Chiralpak AS-H column with the mobile phase consisted of isopropanol and n-hexane. The detection wavelength and the flow rate were set at 254 nm and 0.7 mL/min, respectively. The effects of proportion of organic additives, alcohol displacer and temperature on the separation were investigated. The results indicated that eight chiral drugs were separated on chiral stationary phase of amylase ramification in normal phase chromatographic system. The chromatographic retention and resolution of enantiomers were adjusted by factors, including the changes of the concentration of alcohol displacer in mobile phase, organic alkaline modifier and column temperature. It was shown that the resolution was improved with reducing concentration of alcohol displacer. When the concentration of organic alkaline modifier was 0.2%, the resolution and the peak shape were fairly good. Most racemates mentioned above had the best resolution at column temperature of 25 °C. The best temperature should be kept unchanged in the process of separation so as to obtain stable separation results.

  5. Influence of product phase separation on phospholipase A(2) hydrolysis of supported phospholipid bilayers studied by force microscopy

    DEFF Research Database (Denmark)

    Nielsen, Lars Kildemark; Balashev, K.; Callisen, Thomas Hønger


    concentrations, made by Langmuir-Blodgett deposition, we show that small depressions enriched in products are efficiently promoting enzyme degradation of the bilayer. These small depressions, which are indicative of phase separation, are initially present in samples with 75% products. The kinetics...... of phospholipase A(2) exhibit under certain conditions an initial phase of slow hydrolysis, termed the latency phase, followed by a marked increase in the hydrolysis rate. The appearance of the phase-separated bilayer is strikingly similar to that of bilayers; at the end of the latency phase. By analysis...... of individual nano-scale defects we illustrate a quantitative difference in the growth rates of defects caused by product aggregation and other structural defects. This difference shows for the first time how the enzyme prefers one type of defect to another....

  6. Spatially Resolved Photoemission Spectroscopy to Probe Electronic Phase Separation in Manganites and Related Compounds (United States)

    Das Sarma, Dipankar


    Manganese oxides that exhibit colossal magnetoresistance (CMR) are often characterised by a competition of different electronic phases that critically influence their properties and leads to the coexistence of spatially separated competing phases. Despite extensive experimentation, characteristic length-scales associated with phase coexistence remains an important open question. While theoretical work has pointed to a nanometric length-scale, experiments have uncovered multiple length-scales ranging from the atomic to the sub-micron, covering many orders of magnitude. The role of chemical inhomogeneity in driving this phenomenon is not well understood. Moreover, these early experiments were carried out on polycrystalline and thin film specimens. Here we use a spatially resolved, direct spectroscopic probe for electronic structure with an additional unique sensitivity to chemical compositions to investigate high quality single crystal sample of La1/4Pr3/8Ca3/8MnO3. The formation of distinct electronic domains is observed in absence of any perceptible chemical inhomogeneity, where the relevant length-scale is at least an order of magnitude larger than all previous estimates. The present results, exhibiting memory effects in the domain morphology, suggest that electronic domain formation is intimately connected with long-range strains, often thought to be an important ingredient in the physics of this effect. Additionally, we have also applied this technique to a variety of related materials, such as (LuMnO3)0.79(La5/8Sr3/8MnO3)0.21, and Sr2FexMo1-xO6. Our preliminary results in all these cases suggest that the existence of spatially inhomogeneous electronic phases plays important roles in determining many of the interesting properties of such systems. This work is carried out in collaboration with M. Bertolo, G. Cautero, S-W. Cheong, A. Fujimori, T. Y. Koo, S.R. Krishnakumar, U. Manju, S. Ray, S. La Rosa P. A. Sharma and D. Topwal.

  7. Technical Status Report on the Effect of Phosphate and Aluminum on the Development of Amorphous Phase Separation in Sodium

    Energy Technology Data Exchange (ETDEWEB)

    Cozzi, A.D.


    The objective of the Tank Focus Area ''Optimize Waste Loading'' task is to enhance the definition of the acceptable processing window for high-level waste vitrification plants. One possible manner in which the acceptable processing window may be enhanced is by reducing the uncertainty of various compositional/property models through a specifically defined experimental plan. A reduction in model uncertainty can reduce limitations on current acceptance constraints and may allow for a larger processing or operational window. Enhanced composition/property model predictions coupled with an increased waste loading may decrease the processing time and waste glass disposal costs (i.e., overall lifecycle costs). One of the compositional/property models currently being evaluated by the Tanks Focus Area is related to the development of amorphous phase separation in multi-component borosilicate glasses.Described in this report is the current status for evaluating the effect of phosphorus and alumina on both simple sodium borosilicate and high-level waste glasses on the formation of amorphous phase separation. The goal of this subtask is to increase the understanding of the formation of phase separation by adding significant amounts (3-5 wt. percent) of phosphorus and alumina to well-characterized glasses. Additional scope includes evaluating the effects of thermal history on the formation of amorphous phase separation and durability of select glasses.The development of data, understanding, and quantitative description for composition and kinetic effects on the development of amorphous phase separation will continue in FY99. This effort will provide insight into the compositional and thermal effects on phase stability and will lead to a better understanding of the methods used to predict the development of amorphous phase separation in HLW glasses.

  8. On the implications of aerosol liquid water and phase separation for organic aerosol mass (United States)

    Pye, Havala O. T.; Murphy, Benjamin N.; Xu, Lu; Ng, Nga L.; Carlton, Annmarie G.; Guo, Hongyu; Weber, Rodney; Vasilakos, Petros; Wyat Appel, K.; Hapsari Budisulistiorini, Sri; Surratt, Jason D.; Nenes, Athanasios; Hu, Weiwei; Jimenez, Jose L.; Isaacman-VanWertz, Gabriel; Misztal, Pawel K.; Goldstein, Allen H.


    Organic compounds and liquid water are major aerosol constituents in the southeast United States (SE US). Water associated with inorganic constituents (inorganic water) can contribute to the partitioning medium for organic aerosol when relative humidities or organic matter to organic carbon (OM / OC) ratios are high such that separation relative humidities (SRH) are below the ambient relative humidity (RH). As OM / OC ratios in the SE US are often between 1.8 and 2.2, organic aerosol experiences both mixing with inorganic water and separation from it. Regional chemical transport model simulations including inorganic water (but excluding water uptake by organic compounds) in the partitioning medium for secondary organic aerosol (SOA) when RH > SRH led to increased SOA concentrations, particularly at night. Water uptake to the organic phase resulted in even greater SOA concentrations as a result of a positive feedback in which water uptake increased SOA, which further increased aerosol water and organic aerosol. Aerosol properties, such as the OM / OC and hygroscopicity parameter (κorg), were captured well by the model compared with measurements during the Southern Oxidant and Aerosol Study (SOAS) 2013. Organic nitrates from monoterpene oxidation were predicted to be the least water-soluble semivolatile species in the model, but most biogenically derived semivolatile species in the Community Multiscale Air Quality (CMAQ) model were highly water soluble and expected to contribute to water-soluble organic carbon (WSOC). Organic aerosol and SOA precursors were abundant at night, but additional improvements in daytime organic aerosol are needed to close the model-measurement gap. When taking into account deviations from ideality, including both inorganic (when RH > SRH) and organic water in the organic partitioning medium reduced the mean bias in SOA for routine monitoring networks and improved model performance compared to observations from SOAS. Property updates from

  9. Colourimetric solid-phase extraction coupled with fibre optic reflectance spectroscopy for determination of ascorbic acid in pharmaceutical formulations. (United States)

    Filik, Hayati; Aksu, Duygu; Giray, Derya; Apak, Reşat


    A redox colourimetric solid-phase extraction (C-SPE) procedure for the determination of ascorbic acid (AA) in pharmaceutical formulations was proposed. Iron (III)-2,2'-dipyridyl (Fe(III)-Bpy) reagent solution was used as a colouring reagent for AA and the immobilization of the redox product onto Amberlite XAD-16 resin was achieved. The analyte in the sample reacted with a solid sorbent loaded with the colourimetric reagent (Fe(III)-Bpy) and then quantified directly on the sorbent surface by using a fibre optic reflectance spectrometer (FORS). The amount of AA was reflectometrically determined in a few seconds with a total sample workup and readout time of ∼10 min using only 10-ml sample volumes. The limit of detection (LOD) and quantification (LOQ) values were 0.18 and 0.6 mg L(-1), respectively, and the linear dynamic range for AA extended up to 8.8 mg L(-1). The C-SPE for different extractions (n = 5) gave a relative standard deviation (RSD) of 2.9% at 5.28 mg L(-1) AA level.

  10. Understanding the Tendency of Amorphous Solid Dispersions to Undergo Amorphous–Amorphous Phase Separation in the Presence of Absorbed Moisture


    Rumondor, Alfred C. F.; Wikström, Håkan; Van Eerdenbrugh, Bernard; Taylor, Lynne S.


    Formulation of an amorphous solid dispersion (ASD) is one of the methods commonly considered to increase the bioavailability of a poorly water-soluble small-molecule active pharmaceutical ingredient (API). However, many factors have to be considered in designing an API–polymer system, including any potential changes to the physical stability of the API. In this study, the tendency of ASD systems containing a poorly water-soluble API and a polymer to undergo amorphous–amorphous phase separatio...

  11. 新型复合T型管对液液二相流的分离%Phase separation of liquid-liquid two-phase flow by multi-tube T-junction separator

    Institute of Scientific and Technical Information of China (English)

    杨利民; 赵振莹; 沈小明; 赵立立


    T-junction separator is a novel type of two-phase flow separator with the advantages of compact, continuous, simple, economical and safe operations as well as being easy for installation, replacement and maintenance, but its separation efficiency of the simple T-junction separator is low for separating the two-phase flow. The multi-tube T-junction separator combines several T-junctions in one unit for improving the separation efficiency of the two-phase flow. With kerosene and water as working fluids, the separation experiments were carried out by using the simple T and the multi-tube T-junction units with main pipe in horizontal and branch in vertically upward under the flow patterns of stratified flow and the stratified flow with mixing at interface. The results show that under these two patterns the separation efficiencies of the two phases for the multi-tube T-junctions are much higher than those of the simple T-junction. Increasing the number of connecting tubes in the multi-tube T-junction unit can improve the separation efficiency. Generally, for the stratified flow,the complete separation of two phases can be achieved by a multi-tube T-junction separator with 5 or more connecting tubes; increasing the mixedness of the inlet flow will cause the drop of the separation efficiency peak; the effect of water volume fraction on the separation efficiency is associated with the flow pattern. The phase separation of liquid-liquid two-phase flow by using the multi-tube T-junction separator is a promising technique for industrial application.%T型管分离器是一类新型的二相流分离器,具有集约、连续、简单、经济、安全以及安装、更新、维护方便等优点,缺点是简单T型管作为分离器在分离二相流时的分离效率往往不高,只能起到部分分离的作用.新型复合T型管是对简单T型管的一种改进,以期能提高二相流的分离效率.以煤油和水为液液二相工作介质,用主管水平,侧支管垂

  12. "Plastic" solar cells: self-assembly of bulk heterojunction nanomaterials by spontaneous phase separation. (United States)

    Peet, Jeffrey; Heeger, Alan J; Bazan, Guillermo C


    As the global demand for low-cost renewable energy sources intensifies, interest in new routes for converting solar energy to electricity is rapidly increasing. Although photovoltaic cells have been commercially available for more than 50 years, only 0.1% of the total electricity generated in the United States comes directly from sunlight. The earliest commercial solar technology remains the basis for the most prevalent devices in current use, namely, highly-ordered crystalline, inorganic solar cells, commonly referred to as silicon cells. Another class of solar cells that has recently inspired significant academic and industrial excitement is the bulk heterojunction (BHJ) "plastic" solar cell. Research by a rapidly growing community of scientists across the globe is generating a steady stream of new insights into the fundamental physics, the materials design and synthesis, the film processing and morphology, and the device science and architecture of BHJ technology. Future progress in the fabrication of high-performance BHJ cells will depend on our ability to combine aspects of synthetic and physical chemistry, condensed matter physics, and materials science. In this Account, we use a combination of characterization tools to tie together recent advances in BHJ morphology characterization, device photophysics, and thin-film solution processing, illustrating how to identify the limiting factors in solar cell performance. We also highlight how new processing methods, which control both the BHJ phase separation and the internal order of the components, can be implemented to increase the power conversion efficiency (PCE). The failure of many innovative materials to achieve high performance in BHJ solar cell devices has been blamed on "poor morphology" without significant characterization of either the structure of the phase-separated morphology or the nature of the charge carrier recombination. We demonstrate how properly controlling the "nanomorphology", which is

  13. Safety and enhanced immunogenicity of a hepatitis B core particle Plasmodium falciparum malaria vaccine formulated in adjuvant Montanide ISA 720 in a phase I trial.

    NARCIS (Netherlands)

    Oliveira, G.A.; Wetzel, K.; Calvo-Calle, J.M.; Nussenzweig, R.; Schmidt, A.; Birkett, A.; Dubovsky, F.; Tierney, E.; Gleiter, C.H.; Boehmer, G.; Luty, A.J.F.; Ramharter, M.; Thornton, G.B.; Kremsner, P.G.; Nardin, E.H.


    Highly purified subunit vaccines require potent adjuvants in order to elicit optimal immune responses. In a previous phase I trial, an alum formulation of ICC-1132, a malaria vaccine candidate comprising hepatitis B core (HBc) virus-like particle containing Plasmodium falciparum circumsporozoite

  14. Integration of carboxyl modified magnetic particles and aqueous two-phase extraction for selective separation of proteins. (United States)

    Gai, Qingqing; Qu, Feng; Zhang, Tao; Zhang, Yukui


    Both of the magnetic particle adsorption and aqueous two-phase extraction (ATPE) were simple, fast and low-cost method for protein separation. Selective proteins adsorption by carboxyl modified magnetic particles was investigated according to protein isoelectric point, solution pH and ionic strength. Aqueous two-phase system of PEG/sulphate exhibited selective separation and extraction for proteins before and after magnetic adsorption. The two combination ways, magnetic adsorption followed by ATPE and ATPE followed by magnetic adsorption, for the separation of proteins mixture of lysozyme, bovine serum albumin, trypsin, cytochrome C and myloglobin were discussed and compared. The way of magnetic adsorption followed by ATPE was also applied to human serum separation.

  15. Poly(2-acetoxyethyl methacrylate)/polystyrene latex interpenetrating polymer networks with well-defined phase-separated structure

    Institute of Scientific and Technical Information of China (English)

    Tao Wang; Shan Shi; Li Na Bian; Li Min Zhou; Li Qun Zhao; Shin Ichi Kuroda


    A series of poly (2-acetoxyethyl methacrylate)/polystyrene (PAEMA/PS) latex interpenetrating polymer networks (LIPNs) were prepared by seeded soap-free emulsion polymerization of styrene on the crosslinked PAEMA seed particles using an oil-soluble initiator. These PAEMA/PS LIPNs showed a well-defined phase-separated structure with PS phase dispersing in continuous PAEMA phase. The domain size of PS phase was found to depend on the crosslinking degree of PAEMA seed particles and the amount of second-stage styrene monomer.

  16. A micro gas chromatography with separation capability enhanced by polydimethylsiloxane stationary phase functionalized by carbon nanotubes and graphene. (United States)

    Li, Yubo; Zhang, Runzhou; Wang, Tao; Wang, Youhao; Wang, Yonghuan; Li, Lingfeng; Zhao, Weijun; Wang, Xiaozhi; Luo, Jikui


    Polydimethylsiloxane (PDMS) stationary phases functionalized with multi-walled carbon nanotubes (MWCNTs) and graphene, respectively, for the columns in micro gas chromatography are presented in this paper. To exploit the merits of MWCNTs and graphene in terms of their high specific surface area, low surface energy and chemical inertness, experimental conditions for separation (heating rate and final temperature of temperature programming, flow rate of carrier gas and the volume of samples injection) are investigated, and separations of both polar and nonpolar compound mixtures under these conditions are performed. Compared with PDMS-only coated stationary phases, the functionalization of the phases with carbon nano-materials improves the performance of columns in separation, repeatability, stability and revolution significantly.

  17. Formation of macroporous gel morphology by phase separation in the silica sol-gel system containing nonionic surfactant

    Institute of Scientific and Technical Information of China (English)

    Junsheng Wu; Xiaogang Li; Wei Du; Hua Chen


    The phase separation and gel formation behavior in an alkoxy-derived silica sol-gel system containing Ci6EOi5 has been investigated. Various gel morphologies similar to other sol-gel systems containing organic additives were obtained by changing the preparation conditions. Micrometer-range interconnected porous gels were obtained by freezing transitional structures of phase separation in the sol-gel process. The dependence of the resulting gel morphology on several important reaction parameters such as the starting composition, reaction temperature and acid catalyst concentration was studied in detail. The experimental results indicate that the gel morphology is mainly determined by the time relation between the onset of phase separation and gel formation.

  18. Retention behavior of phenols, anilines, and alkylbenzenes in liquid chromatographic separations using subcritical water as the mobile phase. (United States)

    Yang, Y; Jones, A D; Eaton, C D


    The unique characteristic of subcritical water is its widely tunable physical properties. For example, the polarity (measured by dielectric constant) of water is significantly decreased by raising water temperature. At temperatures of 200-250 °C (under moderate pressure to keep water in the liquid state), the polarity of pure water is similar to that of pure methanol or acetonitrile at ambient conditions. Therefore, pure subcritical water may be able to serve as the mobile phase for reversed-phase separations. To investigate the retention behavior in subcritical water separation, the retention factors of BTEX (benzene, toluene, ethylbenzene, and m-xylene), phenol, aniline, and their derivatives have been determined using subcritical water, methanol/water, and acetonitrile/water systems. Subcritical water separations were also performed using alumina, silica-bonded C18, and poly(styrene-divinylbenzene) columns to study the influence of the stationary phase on analyte retention under subcritical water conditions.

  19. Influence of the Oil Phase and Topical Formulation on the Wound Healing Ability of a Birch Bark Dry Extract. (United States)

    Steinbrenner, Isabel; Houdek, Pia; Pollok, Simone; Brandner, Johanna M; Daniels, Rolf


    Triterpenes from the outer bark of birch are known for various pharmacological effects including enhanced wound healing (WH). A birch bark dry extract (TE) obtained by accelerated solvent extraction showed the ability to form oleogels when it is suspended in oils. Consistency of the oleogels and the dissolved amount of triterpenes varies largely with the used oil. Here we wanted to know to what extent different oils and formulations (oleogel versus o/w emulsion) influence WH. Looking at the plain oils, medium-chain triglycerides (MCT) enhanced WH (ca. 1.4-fold), while e.g. castor oil (ca.0.3-fold) or light liquid paraffin (LLP; ca. 0.5-fold) significantly decreased WH. Concerning the respective oleogels, TE-MCT showed no improvement although the solubility of the TE was high. In contrast, the oleogel of sunflower oil which alone showed a slight tendency to impair WH, enhanced WH significantly (ca. 1.6-fold). These results can be explained by release experiments where the release rate of betulin, the main component of TE, from MCT oleogels was significantly lower than from sunflower oil oleogels. LLP impaired WH as plain oil and even though it released betulin comparable to sunflower oil it still results in an overall negative effect of the oleogel on WH. As a further formulation option also surfactant free o/w emulsions were prepared using MCT, sunflower oil and LLP as a nonpolar oil phase. Depending on the preparation method (suspension or oleogel method) the distribution of the TE varied markedly and affected also release kinetics. However, the released betulin was clearly below the values measured with the respective oleogels. Consequently, none of the emulsions showed a significantly positive effect on WH. In conclusion, our data show that the oil used as a vehicle influences wound healing not only by affecting the release of the extract, but also by having its own vehicle effect on wound healing. This is also of importance for other applications where drugs

  20. TES buffer-induced phase separation of aqueous solutions of several water-miscible organic solvents at 298.15 K: phase diagrams and molecular dynamic simulations. (United States)

    Taha, Mohamed; Lee, Ming-Jer


    Water and the organic solvents tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, 1-propanol, 2-propanol, tert-butanol, acetonitrile, or acetone are completely miscible in all proportions at room temperature. Here, we present new buffering-out phase separation systems that the above mentioned organic aqueous solutions can be induced to form two liquid phases in the presence of a biological buffer 2-[[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]amino]ethanesulfonic acid (TES). The lower liquid phase is rich in water and buffer, and the upper phase is organic rich. This observation has both practical and mechanistic interests. The phase diagrams of these systems were constructed by experimental measurements at ambient conditions. Molecular dynamic (MD) simulations were performed for TES + water + THF system to understand the interactions between TES, water, and organic solvent at molecular level. Several composition-sets for this system, beyond and inside the liquid-liquid phase-splitting region, have been simulated. Interestingly, the MD simulation for compositions inside the phase separation region showed that THF molecules are forced out from the water network to start forming a new liquid phase. The hydrogen-bonds, hydrogen-bonds lifetimes, hydrogen-bond energies, radial distribution functions, coordination numbers, the electrostatic interactions, and the van der Waals interactions between the different pairs have been calculated. Additionally, MD simulations for TES + water + tert-butanol∕acetonitrile∕acetone phase separation systems were simulated. The results from MD simulations provide an explanation for the buffering-out phenomena observed in [TES + water + organic solvent] systems by a mechanism controlled by the competitive interactions of the buffer and the organic solvent with water. The molecular mechanism reported here is helpful for designing new benign separation materials.