WorldWideScience

Sample records for interfacial line tensions

  1. Surface and interfacial tension measurement, theory, and applications

    CERN Document Server

    Hartland, Stanley

    2004-01-01

    This edited volume offers complete coverage of the latest theoretical, experimental, and computer-based data as summarized by leading international researchers. It promotes full understanding of the physical phenomena and mechanisms at work in surface and interfacial tensions and gradients, their direct impact on interface shape and movement, and their significance to numerous applications. Assessing methods for the accurate measurement of surface tension, interfacial tension, and contact angles, Surface and Interfacial Tension presents modern simulations of complex interfacial motions, such a

  2. First-principles prediction of liquid/liquid interfacial tension

    DEFF Research Database (Denmark)

    Andersson, Martin Peter; Bennetzen, M.V.; Klamt, A.

    2014-01-01

    of groundwater aquifers contaminated by chlorinated solvents to drug delivery and a host of industrial processes. Here, we present a model for predicting interfacial tension from first principles using density functional theory calculations. Our model requires no experimental input and is applicable to liquid/liquid......The interfacial tension between two liquids is the free energy per unit surface area required to create that interface. Interfacial tension is a determining factor for two-phase liquid behavior in a wide variety of systems ranging from water flooding in oil recovery processes and remediation...

  3. Coupled Interfacial Tension and Phase Behavior Model Based on Micellar Curvatures

    KAUST Repository

    Torrealba, V. A.

    2017-11-08

    This article introduces a consistent and robust model that predicts interfacial tensions for all microemulsion Winsor types and overall compositions. The model incorporates film bending arguments and Huh\\'s equation and is coupled to phase behavior so that simultaneous tuning of both interfacial tension (IFT) and phase behavior is possible. The oil-water interfacial tension and characteristic length are shown to be related to each other through the hydrophilic-lipophilic deviation (HLD). The phase behavior is tied to the micelle curvatures, without the need for using the net average curvature (NAC). The interfacial tension model is related to solubilization ratios in order to introduce a coupled interfacial tension-phase behavior model for all phase environments. The approach predicts two- and three-phase interfacial tensions and phase behavior (i.e., tie lines and tie triangles) for changes in composition and HLD input parameters, such as temperature, pressure, surfactant structure, and oil equivalent alkane carbon number. Comparisons to experimental data show excellent fits and predictive capability.

  4. Precise pattern replication of polymer blends into nonuniform geometries via reducing interfacial tension between two polymers.

    Science.gov (United States)

    Fang, Liang; Wei, Ming; Shang, Yingrui; Kazmer, David; Barry, Carol; Mead, Joey

    2012-07-10

    Patterned polymer structures with different functionalities have many potential applications. Directed assembly of polymer blends using chemically functionalized patterns during spin-coating has been used to fabricate the patterned polymer structures. For bridging the gap between laboratorial experiments and manufacturing of nanodevices, the polymer blends structures are required to be precisely patterned into nonuniform geometries in a high-rate process, which still is a challenge. In this Article, we demonstrated for the first time that by decreasing the interfacial tension between two polymers polystyrene and poly(acrylic acid) via adding a compatibilizer (polystyrene-b-poly(acrylic acid) ), a polystyrene/poly(acrylic acid) blend was precisely patterned into nonuniform geometries in a high-rate fashion. The patterned nonuniform geometries included angled lines with angles varied from 30° to 150°, T-junctions, square arrays, circle arrays, and arbitrary letter-shaped geometries. The reduction in the interfacial tension improved the line edge roughness and the patterning efficiency of the patterned polymer blends. In addition, the commensurability between characteristic length and pattern periodicity for well-ordered morphologies was also expanded with decreasing interfacial tension. This approach can be easily extended to other functional polymers in a blend and facilitate the applications of patterned polymer structures in biosensors, organic thin-film electronics, and polymer solar cells.

  5. Modelling CO2-Brine Interfacial Tension using Density Gradient Theory

    KAUST Repository

    Ruslan, Mohd Fuad Anwari Che

    2018-03-01

    Knowledge regarding carbon dioxide (CO2)-brine interfacial tension (IFT) is important for petroleum industry and Carbon Capture and Storage (CCS) strategies. In petroleum industry, CO2-brine IFT is especially importance for CO2 – based enhanced oil recovery strategy as it affects phase behavior and fluid transport in porous media. CCS which involves storing CO2 in geological storage sites also requires understanding regarding CO2-brine IFT as this parameter affects CO2 quantity that could be securely stored in the storage site. Several methods have been used to compute CO2-brine interfacial tension. One of the methods employed is by using Density Gradient Theory (DGT) approach. In DGT model, IFT is computed based on the component density distribution across the interface. However, current model is only applicable for modelling low to medium ionic strength solution. This limitation is due to the model only considers the increase of IFT due to the changes of bulk phases properties and does not account for ion distribution at interface. In this study, a new modelling strategy to compute CO2-brine IFT based on DGT was proposed. In the proposed model, ion distribution across interface was accounted for by separating the interface to two sections. The saddle point of tangent plane distance where ( ) was defined as the boundary separating the two sections of the interface. Electrolyte is assumed to be present only in the second section which is connected to the bulk liquid phase side. Numerical simulations were performed using the proposed approach for single and mixed salt solutions for three salts (NaCl, KCl, and CaCl2), for temperature (298 K to 443 K), pressure (2 MPa to 70 MPa), and ionic strength (0.085 mol·kg-1 to 15 mol·kg-1). The simulation result shows that the tuned model was able to predict with good accuracy CO2-brine IFT for all studied cases. Comparison with current DGT model showed that the proposed approach yields better match with the experiment data

  6. Self-destruction and dewetting of thin polymer films the role of interfacial tensions

    CERN Document Server

    Reiter, G; Sharma, A

    2003-01-01

    We present real-time optical microscopy observations of the pattern evolution in self-destruction and subsequent dewetting of thin polymer films based on experiments with polydimethylsiloxane films sandwiched between silicon wafers and aqueous surfactant solutions. A clear scenario consisting of four distinct stages has been identified: amplification of surface fluctuations, break-up of the film and formation of holes, growth and coalescence of holes, and droplet formation and ripening. Besides a linear dependence on film viscosity and surface tension, the time tau for film rupture varied significantly with film thickness h (tau approx h sup 5), as expected from theory. While the role of long-range forces is dominant only in the first stage, the later stages are controlled by the combination of interfacial tensions resulting in the contact angle characterizing the three-phase contact line. During the first stage, the characteristic distance of the pattern remains constant, represented by a time-independent wa...

  7. Interfacial tensions of phase-separated polymer solutions

    Science.gov (United States)

    Xia, K.-Q.; Franck, Carl; Widom, B.

    1992-07-01

    Measurements of the capillary length in phase-separated solutions of polymethylmethacrylate in 3-octanone (PMMA/3-OCT) for each of five different molecular weights of PMMA, and in phase-separated solutions of polystyrene in methylcyclohexane (PS/MCH) for a single molecular weight of polymer, are reported. Measurements on PMMA/3-OCT were by the sessile-drop method; those on PS/MCH were by both the sessile-drop and capillary-rise methods. Interfacial tensions are estimated from estimated density differences and the measured capillary lengths. A theoretically predicted scaling law for the dependence of capillary length on polymer molecular weight and temperature is tested and at least semiquantitatively verified. As by-products of the sample preparation, the molecular-weight dependences of the critical composition and critical solution temperature of PMMA/3-OCT were also determined. The volume fraction of polymer at the critical point, φc, is found to be proportional to the -0.37±0.01 power of the molecular weight, in agreement with values of this exponent found by others for polystyrene solutions.

  8. Interfacial tensions of binary mixtures of ethanol with octane, decane, dodecane, and tetradecane

    International Nuclear Information System (INIS)

    Mejia, Andres; Cartes, Marcela; Segura, Hugo

    2011-01-01

    Highlights: → Experimental interfacial tensions in binary mixtures with aneotropic behavior. → Experimental interfacial tensions for ethanol + hydrocarbon mixtures. → Aneotropic displacement in ethanol mixtures. - Abstract: This contribution is devoted to the experimental characterization of interfacial tensions of a representative group of binary mixtures pertaining to the (ethanol + linear hydrocarbon) series (i.e. octane, decane, dodecane, and tetradecane). Experimental measurements were isothermically performed using a maximum differential bubble pressure technique, which was applied over the whole mole fraction range and over the temperature range 298.15 K < T/K < 318.15 K. Experimental results show that the interfacial tensions of (ethanol + octane or decane) negatively deviate from the linear behavior and that sharp minimum points on concentration, or aneotropes, are observed for each isotherm. The interfacial tensions of (ethanol + dodecane or tetradecane), in turn, are characterized by combined deviations from the linear behavior, and inflecting behavior observed on concentration for each isotherm. The experimental evidence also shows that these latter mixtures are close to exhibit aneotropy. For the case of (ethanol + octane or decane) mixtures, aneotropy was clearly induced by the similarity of the interfacial tension values of the constituents. The inflecting behavior of the interfacial tensions of (ethanol + dodecane or tetradecane), in turn, was observed in the vicinity of the coordinates of the critical point of these mixtures, thus pointing to the fact that the quasi-aneotropic singularity that affects these mixtures was provoked by the proximity of an immiscibility gap of the liquid phase. Finally, the experimental data of interfacial tensions were smoothed with the Scott-Myers expansion, from which it is possible to conclude that the observed aneotropic concentrations weakly depend on temperature for all the analyzed mixtures.

  9. An advanced technique for interfacial tension measurement in liquid- liquid systems

    Energy Technology Data Exchange (ETDEWEB)

    Harris, M.T.; Byers, C.H.

    1989-11-01

    A technique for determining interfacial tension from the shape of an axisymmetric fluid-liquid interface is presented. The technique entails using a novel data acquisition method which uses a high speed video camera to record pendant drop images and a standard graphics computer to precisely measure drop edge coordinates. The interfacial tension is determined by curve-fitting the drop edge coordinates to the Laplace equation. Curve-fitting is achieved by defining the objective function as the sum of the squared perpendicular distance between the theoretical Laplace curve and the experimental data points. An iterative nonlinear parameter estimation technique (the linearization method) is subsequently used to minimize the objective function by varying key parameters (i.e. X{sub o} and Y{sub o} (apex coordinates), R{sub o} and, the shape factor, {beta}{sub c}). The interfacial tension is obtained from {beta}{sub c}. Experimental results show that precisions of 1.2--2.5% are achieved in determining interfacial tensions for various liquid-liquid systems. Furthermore, the effect of temperature on the interfacial tension of several systems, and the effect of salt on the interfacial tension of water-2-ethyl hexanol are presented.

  10. Identifying the effect of polar constituents in coal-derived NAPLs on interfacial tension

    Energy Technology Data Exchange (ETDEWEB)

    Jianzhong Zheng; Susan E. Powers [Clarkson University, Potsdam, NY (United States). Dept. of Civil and Environmental Engineering

    2003-07-15

    Interfacial tension, which is a critical variable affecting multiphase flow of nonaqueous phase liquids (NAPLs) in the subsurface, varies greatly with the composition of complex NAPLs recovered from field sites. Much of this variability stems from the presence of acid and base molecules in the NAPL mixture. The interfacial tension and acid and base concentration in six coal-derived NAPLs were measured. Creosotes generally have lower interfacial tensions due to their higher concentrations of organic acid and base macromolecules as compared with coal tar samples. Interfacial tension is a function of pH, with lower values measured at pH greater than approximately 9. At a neutral pH, the interfacial tensions are inversely proportional to the total acid concentration. Asphaltenes in these coal-derived NAPLs account for most of the acid and base constituents. It is found in this study that acid and base numbers are valuable indicators of interfacial tension and, therefore, the capillary phenomena associated with multiphase flow behavior of NAPLs in the subsurface. 29 refs., 5 figs., 2 tabs.

  11. Dynamically reconfigurable complex emulsions via tunable interfacial tensions

    Science.gov (United States)

    Zarzar, Lauren D.; Sresht, Vishnu; Sletten, Ellen M.; Kalow, Julia A.; Blankschtein, Daniel; Swager, Timothy M.

    2015-02-01

    Emulsification is a powerful, well-known technique for mixing and dispersing immiscible components within a continuous liquid phase. Consequently, emulsions are central components of medicine, food and performance materials. Complex emulsions, including Janus droplets (that is, droplets with faces of differing chemistries) and multiple emulsions, are of increasing importance in pharmaceuticals and medical diagnostics, in the fabrication of microparticles and capsules for food, in chemical separations, in cosmetics, and in dynamic optics. Because complex emulsion properties and functions are related to the droplet geometry and composition, the development of rapid, simple fabrication approaches allowing precise control over the droplets' physical and chemical characteristics is critical. Significant advances in the fabrication of complex emulsions have been made using a number of procedures, ranging from large-scale, less precise techniques that give compositional heterogeneity using high-shear mixers and membranes, to small-volume but more precise microfluidic methods. However, such approaches have yet to create droplet morphologies that can be controllably altered after emulsification. Reconfigurable complex liquids potentially have great utility as dynamically tunable materials. Here we describe an approach to the one-step fabrication of three- and four-phase complex emulsions with highly controllable and reconfigurable morphologies. The fabrication makes use of the temperature-sensitive miscibility of hydrocarbon, silicone and fluorocarbon liquids, and is applied to both the microfluidic and the scalable batch production of complex droplets. We demonstrate that droplet geometries can be alternated between encapsulated and Janus configurations by varying the interfacial tensions using hydrocarbon and fluorinated surfactants including stimuli-responsive and cleavable surfactants. This yields a generalizable strategy for the fabrication of multiphase emulsions with

  12. The interfacial surface tension of a quark-gluon plasma fireball in a ...

    Indian Academy of Sciences (India)

    We calculate the interfacial surface tension of a QGP-fireball in a hadronic medium in the Ramanathan et al statistical model. The constancy of the ratio of the surface tension with the cube of the critical transition temperature is in overall accordance with lattice QCD findings. It is in complete agreement with a recent MIT bag ...

  13. Relative viscosity of emulsions in simple shear flow: Temperature, shear rate, and interfacial tension dependence

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Se Bin; Lee, Joon Sang [Dept. of Mechanical Engineering, Yonsei Unversity, Seoul (Korea, Republic of)

    2015-08-15

    We simulate an emulsion system under simple shear rates to analyze its rheological characteristics using the lattice Boltzmann method (LBM). We calculate the relative viscosity of an emulsion under a simple shear flow along with changes in temperature, shear rate, and surfactant concentration. The relative viscosity of emulsions decreased with an increase in temperature. We observed the shear-thinning phenomena, which is responsible for the inverse proportion between the shear rate and viscosity. An increase in the interfacial tension caused a decrease in the relative viscosity of the decane-in-water emulsion because the increased deformation caused by the decreased interfacial tension significantly influenced the wall shear stress.

  14. Modeling of Pressure Dependence of Interfacial Tension Behaviors of Supercritical CO2 + Crude Oil Systems Using a Basic Parachor Expression

    International Nuclear Information System (INIS)

    Dayanand, S.

    2017-01-01

    Parachor based expressions (basic and mechanistic) are often used to model the experimentally observed pressure dependence of interfacial tension behaviors of complex supercritical carbon dioxide (sc-CO 2 ) and crude oil mixtures at elevated temperatures. However, such modeling requires various input data (e.g. compositions and densities of the equilibrium liquid and vapor phases, and molecular weights and diffusion coefficients for various components present in the system). In the absence of measured data, often phase behavior packages are used for obtaining these input data for performing calculations. Very few researchers have used experimentally measured input data for performing parachor based modeling of the experimental interfacial tension behaviors of sc-CO 2 and crude oil systems that are of particular interest to CO 2 injection in porous media based enhanced oil recovery operations. This study presents the results of parachor based modeling performed to predict pressure dependence of interfacial tension behaviors of a complex sc-CO 2 and crude oil system for which experimentally measured data is available in public domain. Though parachor model based on calculated interfacial tension behaviors shows significant deviation from the measured behaviors in high interfacial tension region, difference between the calculated and the experimental behaviors appears to vanish in low interfacial tension region. These observations suggest that basic parachor expression based calculated interfacial tension behaviors in low interfacial tension region follow the experimental interfacial tension behaviors more closely. An analysis of published studies (basic and mechanistic parachor expressions based on modeling of pressure dependence of interfacial tension behaviors of both standard and complex sc-CO 2 and crude oil systems) and the results of this study reinforce the need of better description of gas-oil interactions for robust modeling of pressure dependence of

  15. Interfacial tension and wettability in water-carbon dioxide systems: Experiments and self-consistent field modeling

    NARCIS (Netherlands)

    Banerjee, S.; Hassenklover, E.; Kleijn, J.M.; Cohen Stuart, M.A.; Leermakers, F.A.M.

    2013-01-01

    This paper presents experimental and modeling results on water–CO2 interfacial tension (IFT) together with wettability studies of water on both hydrophilic and hydrophobic surfaces immersed in CO2. CO2–water interfacial tension (IFT) measurements showed that the IFT decreased with increasing

  16. Interfacial tension measurement between CO2 and brines under high temperature and elevated pressure conditions

    Science.gov (United States)

    Li, X.; Boek, E. S.; Maitland, G. C.; Trusler, J. P. M.

    2012-04-01

    We have investigated the dependence of interfacial tension of (CO2 + brine) on temperature, pressure and salinity (including both salt type and molality) over the range of conditions applicable to CO2 storage in saline aquifers. The study covered a wide range of measurements of the interfacial tensions between carbon dioxide and (NaCl + KCl)(aq), CaCl2(aq), MgCl2(aq), Na2SO4(aq), KHCO3(aq), NaHCO3(aq) and two laboratory constructed brines with molality ranging from (0.3 to 5.0) mol·kg-1. The measurements were made at temperatures between (298 and 448) K at various pressures up to 50 MPa, using the pendant drop method in a high-pressure view cell filled with water-saturated CO2. The drop to be imaged was created by injecting brine from a high-pressure syringe pump into a capillary sealed through the top of the cell. The expanded uncertainties of the experimental state variables at 95 % confidence are +0.05 K in temperature and +70 kPa in pressure. For the interfacial tension, the overall expanded relative uncertainty at 95 % confidence was +1.6%. The experimental results show that interfacial tension for all the systems increases linearly with molality, indicating that relatively few measurements and simple interpolation procedures are adequate for describing this property accurately over wide ranges of conditions.

  17. Interfacial Tensions of Aged Organic Aerosol Particle Mimics Using a Biphasic Microfluidic Platform.

    Science.gov (United States)

    Metcalf, Andrew R; Boyer, Hallie C; Dutcher, Cari S

    2016-02-02

    Secondary organic aerosol (SOA) particles are a major component of atmospheric particulate matter, yet their formation processes and ambient properties are not well understood. These complex particles often contain multiple interfaces due to internal aqueous- and organic-phase partitioning. Aerosol interfaces can profoundly affect the fate of condensable organic compounds emitted into the atmosphere by altering the way in which ambient organic vapors interact with suspended particles. To accurately predict the evolution of SOA in the atmosphere, we must improve our understanding of aerosol interfaces. In this work, biphasic microscale flows are used to measure interfacial tension of reacting methylglyoxal, formaldehyde, and ammonium sulfate aqueous mixtures with a surrounding oil phase. Our experiments show a suppression of interfacial tension as a function of organic content that remains constant with reaction time for methylglyoxal-ammonium sulfate systems. We also reveal an unexpected time dependence of interfacial tension over a period of 48 h for ternary solutions of both methylglyoxal and formaldehyde in aqueous ammonium sulfate, indicating a more complicated behavior of surface activity where there is competition among dissolved organics. From these interfacial tension measurements, the morphology of aged atmospheric aerosols with internal liquid-liquid phase separation is inferred.

  18. Calculation of Interfacial Tensions of Hydrocarbon-water Systems under Reservoir Conditions

    DEFF Research Database (Denmark)

    Zuo, You-Xiang; Stenby, Erling Halfdan

    1998-01-01

    Assuming that the number densities of each component in a mixture are linearly distributed across the interface between the coexisting vapor-liquid or liquid-liquid phases, we developed in this research work a linear-gradient-theory (LGT) model for computing the interfacial tension of hydrocarbon......-brine systems. The new model was tested on a number of hydrocarbon-water/brine mixtures and two crude oil-water systems under reservoir conditions. The results show good agreement between the predicted and the experimental interfacial tension data.......Assuming that the number densities of each component in a mixture are linearly distributed across the interface between the coexisting vapor-liquid or liquid-liquid phases, we developed in this research work a linear-gradient-theory (LGT) model for computing the interfacial tension of hydrocarbon-water...... mixtures on the basis of the SRK equation of state. With this model, it is unnecessary to solve the time-consuming density-profile equations of the gradient-theory model. In addition, a correlation was developed for representing the effect of electrolytes on the interfacial tension of hydrocarbon...

  19. Calculation of Interfacial Tensions of Hydrocarbon-water Systems under Reservoir Conditions

    DEFF Research Database (Denmark)

    Zuo, You-Xiang; Stenby, Erling Halfdan

    1998-01-01

    Assuming that the number densities of each component in a mixture are linearly distributed across the interface between the coexisting vapor-liquid or liquid-liquid phases, we developed in this research work a linear-gradient-theory (LGT) model for computing the interfacial tension of hydrocarbon......-brine systems. The new model was tested on a number of hydrocarbon-water/brine mixtures and two crude oil-water systems under reservoir conditions. The results show good agreement between the predicted and the experimental interfacial tension data.......Assuming that the number densities of each component in a mixture are linearly distributed across the interface between the coexisting vapor-liquid or liquid-liquid phases, we developed in this research work a linear-gradient-theory (LGT) model for computing the interfacial tension of hydrocarbon......-water mixtures on the basis of the SRK equation of state. With this model, it is unnecessary to solve the time-consuming density-profile equations of the gradient-theory model. In addition, a correlation was developed for representing the effect of electrolytes on the interfacial tension of hydrocarbon...

  20. Effects of non-uniform interfacial tension in small Reynolds number ...

    Indian Academy of Sciences (India)

    physics pp. 493–507. Effects of non-uniform interfacial tension in small Reynolds number flow past a spherical liquid drop. D P MASON1,∗ and G M MOREMEDI2. 1Centre for Differential Equations, Continuum Mechanics and Applications,. School of Computational and Applied Mathematics, University of the Witwatersrand, ...

  1. Prediction of aliphatic and aromatic oil-water interfacial tension at temperatures >100 °C using COSMO-RS

    DEFF Research Database (Denmark)

    Andersson, Martin Peter; Eckert, F.; Reinisch, J.

    2017-01-01

    As a contribution to the 9th Industrial Fluid Property Simulation Challenge on predicting interfacial tension between water and a set of non-polar oils at temperatures up to 170 °C we have used our first-principles based model, which is based on density functional theory and uses COSMO-RS implicit...... solvent model thermodynamics. Our calculations predict that the oil-water interfacial tension starts to drop significantly for alkanes at temperatures above ∼100 °C, and the oil-water interfacial tension drops significantly with increased temperature already above ∼25 °C for aromatic oils. In the range...

  2. Surface/interfacial free energies and the surface tension of uranium dioxide

    International Nuclear Information System (INIS)

    Deshpande, M.S.; Desai, P.D.; Solomon, A.A.

    1984-01-01

    The purpose of this study is to review literature on surface/interfacial free energies and surface tension of UO/sub 2 +- x/. The data available in the literature are reviewed and critical evaluation and analyses of the available data are made by comparing them not only with each other, but also with the estimated values based on the available theoretical models. In light of the complexity of the material and the problems associated with the available literature data, no recommendations of surface/interfacial free energies and surface tension values are possible at this time. However, an attempt is made to point out problems associated with the data in general and also to develop procedures that can be used to analyze surface energies

  3. A Linear Gradient Theory Model for Calculating Interfacial Tensions of Mixtures

    DEFF Research Database (Denmark)

    Zou, You-Xiang; Stenby, Erling Halfdan

    1996-01-01

    containing supercritical methane, argon, nitrogen, and carbon dioxide gases at high pressure. With this model it is unnecessary to solve the time-consuming density profile equations of the gradient theory model. The model has been tested on a number of mixtures at low and high pressures. The results show...... with proper scaling behavior at the critical point is at least required.Key words: linear gradient theory; interfacial tension; equation of state; influence parameter; density profile.......In this research work, we assumed that the densities of each component in a mixture are linearly distributed across the interface between the coexisting vapor and liquid phases, and we developed a linear gradient theory model for computing interfacial tensions of mixtures, especially mixtures...

  4. Recent Advances in Nanoparticles Enhanced Oil Recovery: Rheology, Interfacial Tension, Oil Recovery, and Wettability Alteration

    Directory of Open Access Journals (Sweden)

    Muhammad Shahzad Kamal

    2017-01-01

    Full Text Available Chemically enhanced oil recovery methods are utilized to increase the oil recovery by improving the mobility ratio, altering the wettability, and/or lowering the interfacial tension between water and oil. Surfactants and polymers have been used for this purpose for the last few decades. Recently, nanoparticles have attracted the attention due to their unique properties. A large number of nanoparticles have been investigated for enhanced oil recovery applications either alone or in combination with surfactants and/or polymers. This review discusses the various types of nanoparticles that have been utilized in enhanced oil recovery. The review highlights the impact of nanoparticles on wettability alteration, interfacial tension, and rheology. The review also covers the factors affecting the oil recovery using nanoparticles and current challenges in field implementation.

  5. Microfluidic Tensiometry Technique for the Characterization of the Interfacial Tension between Immiscible Liquids.

    Science.gov (United States)

    Honaker, Lawrence W; Lagerwall, Jan P F; Jampani, V S R

    2018-02-20

    The interfacial tension between two immiscible fluids is of critical importance for understanding many natural phenomena as well as in industrial production processes; however, it can be challenging to measure this parameter with high accuracy. Most commonly used techniques have significant shortcomings because of their reliance on other data such as density or viscosity. To overcome these issues, we devise a technique that works with very small sample quantities and does not require any data about either fluid, based on micropipette aspiration techniques. The method facilitates the generation of a droplet of one fluid inside of the other, followed by immediate in situ aspiration of the droplet into a constricted channel. A modified Young-Laplace equation is then used to relate the pressure needed to produce a given deformation of the droplet's radius to the interfacial tension. We demonstrate this technique on different systems with interfacial tensions ranging from sub-millinewton per meter to several hundred millinewton per meter, thus over 4 orders of magnitude, obtaining precise results in agreement with the literature solely from experimental observations of the droplet deformation.

  6. Studies on a Foam System of Ultralow Interfacial Tension Applied in Daqing Oilfield after Polymer Flooding

    Directory of Open Access Journals (Sweden)

    Hong-sheng Liu

    2013-01-01

    Full Text Available In order to study the effects of oil displacement by a foam system of ultralow interfacial tension, the interfacial activities and foam properties of a nonionic gemini surfactant (DWS were investigated under Daqing Oilfield reservoir conditions. Injection methods and alternate cycle of the foam system were discussed here on the basis of results from core flow experiments. It was obtained that the surface tension of DWS was approximately 25 mN/m, and ultralow interfacial tension was reached between oil and DWS with a surfactant concentration between 0.05wt% and 0.4wt%. The binary system showed splendid foam performances, and the preferential surfactant concentration was 0.3wt% with a polymer concentration of 0.2wt%. When gas and liquid were injected simultaneously, flow control capability of the foam reached its peak at the gas-liquid ratio of 3 : 1. Enhanced oil recovery factor of the binary foam system exceeded 10% in a parallel natural cores displacement after polymer flooding.

  7. A molecular dynamics study of local pressures and interfacial tensions of SDS micelles and dodecane droplets in water.

    Science.gov (United States)

    Kitabata, Masahiro; Fujimoto, Kazushi; Yoshii, Noriyuki; Okazaki, Susumu

    2016-06-14

    To obtain the radial (normal) and lateral (transverse) components of the local pressure tensor, PN(R) and PT(R), respectively, and the interfacial tension of micelles, molecular dynamics (MD) calculations were performed for spherical sodium dodecyl sulfate (SDS) micelles. The local pressure tensor was calculated as a function of radial distance R using the Irving-Kirkwood formula. Similar MD calculations were also carried out for an n-dodecane droplet in water to compare the differences in the local pressure and interfacial tension values with those of the micelles. The calculated interfacial tensions were 20 ± 5 and 44 ± 10 mN/m for the SDS micelles and dodecane droplets, respectively. The excess free energies due to the interfacial tension were 340 and 1331 kJ/mol for the SDS micelle and dodecane droplet, respectively. The micelles are stabilized by 991 kJ/mol by covering their hydrophobic cores with hydrophilic groups. The dodecane droplet has a large interfacial tension caused by the zero or positive values of PN(R) - PT(R) at all values of R. In contrast, the small interfacial tension in the SDS micelles comes from the negative PN(R) - PT(R) values over a wide range of R. The pressure difference between the inside and outside of the oil droplet and its interfacial tension well satisfies the Laplace equation. However, the hydrophobic core of the SDS micelle is quite different from the liquid alkane, and the SDS micelles do not follow Laplace's picture. Decomposing the interfacial tension into contributions from various interactions, it is found that those between charged and polar groups dominate the interfacial tension of the SDS micelles. The positive electrostatic potential (1.3 V) on the micelle surface and the negative potential (-0.15 V) on the oil droplet contribute to the interfacial tensions by 19 and 0.5 mN/m, respectively. Thus, the interfacial tension of the SDS micelles is produced by electrostatic interactions, in contrast to the dodecane

  8. Interfacial layers from the protein HFBII hydrophobin: dynamic surface tension, dilatational elasticity and relaxation times.

    Science.gov (United States)

    Alexandrov, Nikola A; Marinova, Krastanka G; Gurkov, Theodor D; Danov, Krassimir D; Kralchevsky, Peter A; Stoyanov, Simeon D; Blijdenstein, Theodorus B J; Arnaudov, Luben N; Pelan, Eddie G; Lips, Alex

    2012-06-15

    The pendant-drop method (with drop-shape analysis) and Langmuir trough are applied to investigate the characteristic relaxation times and elasticity of interfacial layers from the protein HFBII hydrophobin. Such layers undergo a transition from fluid to elastic solid films. The transition is detected as an increase in the error of the fit of the pendant-drop profile by means of the Laplace equation of capillarity. The relaxation of surface tension after interfacial expansion follows an exponential-decay law, which indicates adsorption kinetics under barrier control. The experimental data for the relaxation time suggest that the adsorption rate is determined by the balance of two opposing factors: (i) the barrier to detachment of protein molecules from bulk aggregates and (ii) the attraction of the detached molecules by the adsorption layer due to the hydrophobic surface force. The hydrophobic attraction can explain why a greater surface coverage leads to a faster adsorption. The relaxation of surface tension after interfacial compression follows a different, square-root law. Such behavior can be attributed to surface diffusion of adsorbed protein molecules that are condensing at the periphery of interfacial protein aggregates. The surface dilatational elasticity, E, is determined in experiments on quick expansion or compression of the interfacial protein layers. At lower surface pressures (<11 mN/m) the experiments on expansion, compression and oscillations give close values of E that are increasing with the rise of surface pressure. At higher surface pressures, E exhibits the opposite tendency and the data are scattered. The latter behavior can be explained with a two-dimensional condensation of adsorbed protein molecules at the higher surface pressures. The results could be important for the understanding and control of dynamic processes in foams and emulsions stabilized by hydrophobins, as well as for the modification of solid surfaces by adsorption of such

  9. A finite element based algorithm for determining interfacial tension (gamma) from pendant drop profiles.

    Science.gov (United States)

    Dingle, Nicole M; Tjiptowidjojo, Kristianto; Basaran, Osman A; Harris, Michael T

    2005-06-15

    This paper introduces a robust algorithm to determine the interfacial tension (gamma) from pendant drop profiles using the Galerkin finite element method (gamma-PD-FEM) to solve the axisymmetric form of the Young-Laplace (YL) equation. In this algorithm, the theoretical profiles are generated by solving the spherical coordinate form of the YL equation. gamma-PD-FEM also solves for the parameter estimates by minimizing the difference between the theoretical and experimental surface functions, f(theta). This technique is compared to the widely used method of converting the YL equation to the three arc length-based (ALB) first-order ODEs developed by Bashforth and Adams (BA) in 1883, or as denoted in this paper, the gamma-PD-BA method. The drop apex is the initial condition for the gamma-PD-BA algorithm and the integration is terminated at a specified location along the drop profile. In contrast to techniques based on the BA approach, computation of the theoretical drop profile in gamma-PD-FEM is obtained from a second-order ordinary differential equation and requires boundary conditions at the drop apex and at the contact line of the drop to the nozzle. By incorporating both boundary conditions into the problem formulation, the algorithm can also determine if the drop shape is at static equilibrium. Results to be presented include an outline of the computer algorithm, and comparison of gamma values obtained from the gamma-PD-FEM and the traditional gamma-PD-BA method using simulated and experimental drop profile data sets.

  10. Origin of line tension for a Lennard-Jones nanodroplet

    Science.gov (United States)

    Weijs, Joost H.; Marchand, Antonin; Andreotti, Bruno; Lohse, Detlef; Snoeijer, Jacco H.

    2011-02-01

    The existence and origin of line tension has remained controversial in literature. To address this issue, we compute the shape of Lennard-Jones nanodrops using molecular dynamics and compare them to density functional theory in the approximation of the sharp kink interface. We show that the deviation from Young's law is very small and would correspond to a typical line tension length scale (defined as line tension divided by surface tension) similar to the molecular size and decreasing with Young's angle. We propose an alternative interpretation based on the geometry of the interface at the molecular scale.

  11. Studies on interfacial tension and contact angle of synthesized surfactant and polymeric from castor oil for enhanced oil recovery

    Science.gov (United States)

    Babu, Keshak; Pal, Nilanjan; Bera, Achinta; Saxena, V. K.; Mandal, Ajay

    2015-10-01

    New synthesized polymeric surfactants have immensely attracted the researchers for further development of chemical enhanced oil recovery method particularly in surfactant flooding. Contact angle and interfacial tension measurement tests are the effective ways to identify proper chemicals/surfactants for enhanced oil recovery by chemical/surfactant flooding. In the present study a new polymeric surfactant was synthesized from pre-synthesized sodium methyl ester sulfonate (surfactant) and acrylamide for application in chemical enhanced oil recovery. The synthesized surfactant and polymeric surfactant were used to measure interfacial tension between their aqueous phase and crude oil phase to investigate the efficiency of the surfactants in reduction of interfacial tension. The synthesized polymeric surfactant has also ability to control the mobility because of its viscous nature in aqueous solution. Contact angles of solid-crude oil-surfactant interface were also measured to study the effect of the synthesized surfactant and polymeric surfactant on wettability alteration mechanism. Synergistic effect was studied by using NaCl and synthesized surfactants on interfacial tension. Dynamic interfacial tensions of the surfactant and polymeric surfactant solutions with crude oil were measured at different NaCl concentrations. Interfacial tension was found to be lowered up to 10-2 to 10-3 mN/m which is effective for oil recovery. Measurement of contact angle indicates the wettability change of the quartz surface. Comparative studies on efficiencies of synthesized sodium methyl ester sulfonate surfactant and polymeric surfactant were also carried out with respect to interfacial tension reduction and contact angle change.

  12. Interfacial Tension and Surface Pressure of High Density Lipoprotein, Low Density Lipoprotein, and Related Lipid Droplets

    DEFF Research Database (Denmark)

    Ollila, O. H. S.; Lamberg, A.; Lehtivaara, M.

    2012-01-01

    Lipid droplets play a central role in energy storage and metabolism on a cellular scale. Their core is comprised of hydrophobic lipids covered by a surface region consisting of amphiphilic lipids and proteins. For example, high and low density lipoproteins (HDL and LDL, respectively....... Here we use coarse-grained molecular-dynamics simulations to consider a number of related issues by calculating the interfacial tension in protein-free lipid droplets, and in HDL and LDL particles mimicking physiological conditions. First, our results suggest that the curvature dependence...

  13. Interfacial tension, morphology and linear viscoelasticity behavior of PP/PS blends

    Directory of Open Access Journals (Sweden)

    Paulo H. P. Macaúbas

    1999-12-01

    Full Text Available Blends of polypropylene and polystyrene compatibilized with styrene-butadiene-styrene (SBS or styrene-ethylene/butylene-styrene (SEBS copolymers were studied. The morphology of these blends was studied by Scanning Electron Microscopy. Emulsion curves relating the average radius of the dispersed phase to the concentration of compatibilizer added to the blend were obtained. The rheological behavior of the blends was studied by small amplitude oscillatory shear, and correlated to the morphological observations. The interfacial tension between the components of the blends was evaluated from the rheological data. In addition, the applicability of time-temperature superposition (TTS method for PP/PS blend was studied.

  14. General approach for solving the density gradient theory in the interfacial tension calculations

    DEFF Research Database (Denmark)

    Liang, Xiaodong; Michelsen, Michael Locht

    2017-01-01

    Within the framework of the density gradient theory, the interfacial tension can be calculated by finding the density profiles that minimize an integral of two terms over the system of infinite width. It is found that the two integrands exhibit a constant difference along the interface for a finite...... property evaluations compared to other methods. The performance of the algorithm with recommended parameters is analyzed for various systems, and the efficiency is further compared with the geometric-mean density gradient theory, which only needs to solve nonlinear algebraic equations. The results show...... that the algorithm is only 5-10 times less efficient than solving the geometric-mean density gradient theory....

  15. Competitive adsorption of surfactants and hydrophilic silica particles at the oil-water interface: interfacial tension and contact angle studies.

    Science.gov (United States)

    Pichot, R; Spyropoulos, F; Norton, I T

    2012-07-01

    The effect of surfactants' type and concentration on the interfacial tension and contact angle in the presence of hydrophilic silica particles was investigated. Silica particles have been shown to have an antagonistic effect on interfacial tension and contact angle in the presence of both W/O and O/W surfactants. Silica particles, combined with W/O surfactant, have no effect on interfacial tension, which is only dictated by the surfactant concentration, while they strongly affect interfacial tension when combined with O/W surfactants. At low O/W surfactant, both particles and surfactant are adsorbed at the interface, modifying the interface structure. At higher concentration, interfacial tension is only dictated by the surfactant. By increasing the surfactant concentration, the contact angle that a drop of aqueous phase assumes on a glass substrate placed in oil media decreases or increases depending on whether the surfactant is of W/O or O/W type, respectively. This is due to the modification of the wettability of the glass by the oil or water induced by the surfactants. Regardless of the surfactant's type, the contact angle profile was dictated by both particles and surfactant at low surfactant concentration, whereas it is dictated by the surfactant only at high concentration. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Calculation of the interfacial tension of the methane-water system with the linear gradient theory

    DEFF Research Database (Denmark)

    Schmidt, Kurt A. G.; Folas, Georgios; Kvamme, Bjørn

    2007-01-01

    The linear gradient theory (LGT) combined with the Soave-Redlich-Kwong (SRK EoS) and the Peng-Robinson (PR EoS) equations of state has been used to correlate the interfacial tension data of the methane-water system. The pure component influence parameters and the binary interaction coefficient...... for the mixture influence parameter have been obtained for this system. The model was successfully applied to correlate the interfacial tension data set to within 2.3% for the linear gradient theory and the SRK EoS (LGT-SRK) and 2.5% for the linear gradient theory and PE EoS (LGT-PR). A posteriori comparison...... of data not used in the parameterisation were to within 3.2% for the LGT-SRK model and 2.7% for the LGT-PR model. An exhaustive literature review resulted in a large database for the investigation which covers a wide range of temperature and pressures. The results support the success of the linear...

  17. Structure and Interfacial Tension of a Hard-Rod Fluid in Planar Confinement.

    Science.gov (United States)

    Brumby, Paul E; Wensink, Henricus H; Haslam, Andrew J; Jackson, George

    2017-10-24

    The structural properties and interfacial tension of a fluid of rodlike hard-spherocylinder particles in contact with hard structureless flat walls are studied by means of Monte Carlo simulation. The calculated surface tension between the rod fluid and the substrate is characterized by a nonmonotonic trend as a function of the bulk concentration (density) over the range of isotropic bulk concentrations. As suggested by earlier theoretical studies, a surface-ordering scenario is confirmed by our simulations: the local orientational order close to the wall changes from uniaxial to biaxial nematic when the bulk concentration reaches about 85% of the value at the onset of the isotropic-nematic phase transition. The surface ordering coincides with a wetting transition whereby the hard wall is wetted by a nematic film. Accurate values of the fluid-solid surface tension, the adsorption, and the average particle-wall contact distance are reported (over a broad range of densities into the dense nematic region for the first time), which can serve as a useful benchmark for future theoretical and experimental studies on confined rod fluids. The simulation data are supplemented with predictions from second-virial density functional theory, which are in good qualitative agreement with the simulation results.

  18. Effect of surface-active additives on the temperature behavior of interfacial tension in water- n-hexane systems

    Science.gov (United States)

    Ataev, G. M.

    2012-03-01

    The temperature dependence of interface tension in a water- n-hexane system without additives and after addition of stearic acid was experimentally studied at four different concentrations. A method for determining the excess surface chemical potential from experimental data on the temperature dependence of interfacial or surface tension is proposed for a diluted solution of surface-active impurity. The excess surface chemical potential of stearic acid at the interface of a water- n-hexane binary mixture is determined.

  19. Line tension and the shape of nanodroplets.

    Science.gov (United States)

    Schimmele, L; Dietrich, S

    2009-12-01

    Various factors are discussed which might influence the equilibrium contact angle of nanodroplets placed on a solid substrate. Special emphasis is put on the possible role of the dependence of the solid-liquid interface tension [Formula: see text] on the pressure in the liquid, which in nanodrops considerably exceeds the saturation pressure. We show that certain published data regarding that dependence are meaningless because these have been deduced based on an inconsistent data analysis.

  20. Improved Oil Recovery in Chalk. Spontaneous Imbibition affected by Wettability, Rock Framework and Interfacial Tension

    Energy Technology Data Exchange (ETDEWEB)

    Milter, J.

    1996-12-31

    The author of this doctoral thesis aims to improve the oil recovery from fractured chalk reservoirs, i.e., maximize the area of swept zones and their displacement efficiencies. In order to identify an improved oil recovery method in chalk, it is necessary to study wettability of calcium carbonate and spontaneous imbibition potential. The thesis contains an investigation of thin films and wettability of single calcite surfaces. The results of thin film experiments are used to evaluate spontaneous imbibition experiments in different chalk types. The chalk types were described detailed enough to permit considering the influence of texture, pore size and pore throat size distributions, pore geometry, and surface roughness on wettability and spontaneous imbibition. Finally, impacts of interfacial tension by adding anionic and cationic surfactants to the imbibing water phase are studied at different wettabilities of a well known chalk material. 232 refs., 97 figs., 13 tabs.

  1. Sensitivity Analysis of Interfacial Tension on Saturation and Relative Permeability Model Predictions

    KAUST Repository

    Abdallah, Wael

    2011-05-18

    Interfacial tension (IFT) measurements of Dodecane/brine systems at different concentrations and Dodecane/deionized water subject to different Dodecane purification cycles were taken over extended durations at room temperature and pressure to investigate the impact of aging. When a fresh droplet was formed, a sharp drop in IFT was observed assumed to be a result of intrinsic impurity adsorption at the interface. The subsequent measurements exhibited a prolonged equilibration period consistent with diffusion from the bulk phase to the interface. Our results indicate that minute amounts of impurities present in experimental chemical fluids "used as received" have a drastic impact on the properties of the interface. Initial and equilibrium IFT are shown to be dramatically different, therefore it is important to be cautious of utilizing IFT values in numerical models. The study demonstrates the impact these variations in IFT have on relative permeability relationships by adopting a simple pore network model simulation.

  2. Interfacial stability of soil covers on lined surface impoundments

    International Nuclear Information System (INIS)

    Mitchell, D.H.; Gates, T.E.

    1986-04-01

    The factors affecting the interfacial stability of soil covers on geomembranes were examined to determine the maximum stable slopes for soil cover/geomembrane systems. Several instances of instability of soil covers on geomembranes have occurred at tailings ponds, leaving exposed geomembranes with the potential for physical ddamage and possibly chemical and ultraviolet degradation. From an operator's viewpoint, it is desirable to maximize the slope of lined facilities in order to maximize the volume-to-area ratio; however, the likelihood for instability also increases with increasing slope. Frictional data obtained from direct shear tests are compared with stability data obtained using a nine-square-meter (m 2 ) engineering-scale test stand to verify that direct shear test data are valid in slope design calculations. Interfacial frictional data from direct shear tests using high-density polyethylene and a poorly graded sand cover agree within several degrees with the engineering-scale tests. Additional tests with other soils and geomembranes are planned. The instability of soil covers is not always an interfacial problem; soil erosion and limited drainage capacity are additional factors that must be considered in the design of covered slopes. 7 refs., 5 figs., 2 tabs

  3. Effects of chemical dispersants on oil-brine interfacial tension and droplet formation

    International Nuclear Information System (INIS)

    Khelifa, A.; So, L.L.C.

    2009-01-01

    The dispersion of oil spilled in water is influenced by chemical dispersants via the modification of the interfacial properties of the oil, such as oil-brine interfacial tension (IFT). In this study, the physical properties and dispersion of oil were measured in order to determine the effects of chemical dispersants on IFT and oil viscosity and the effects on oil droplet formation. In theory, the maximum size of oil droplet that forms under turbulent mixing increases with IFT. Therefore, a reduction in IFT reduces the size distribution of oil droplets. This paper presented the results of an ongoing project aimed at providing quantitative understanding the influence that chemical dispersants have on the size distribution of oil droplets and oil dispersion. Findings showed that a valid approach is to separate the direct effects of chemical dispersants on oil properties, specifically oil-brine IFT and the effects of mixing on dispersion of chemically treated oil. Under constant mixing conditions, the reduction of the maximum oil droplet size that overcomes the breakage process is determined by the effects of chemical dispersant on oil properties. This correlates well with the dispersant-to-oil ratio (DOR) up to the critical micelle concentration (CMC). This good agreement can be attributed to the reduction of IFT with DOR. It was concluded that the reduction of IFT with dispersant concentration is an additional signature of oil composition on droplet formation, while mixing energy is an external parameter that is independent of oil properties. 17 refs., 3 tabs., 9 figs

  4. On understanding microemulsions : I. Interfacial tensions and adsorptions of SDS and pentanol at the cyclohexane/water interface

    NARCIS (Netherlands)

    Verhoeckx, G.J.; Bruyn, P.L. de; Overbeek, J.Th.G.

    1987-01-01

    We measured interfacial tensions using the spinning drop technique in two-phase oil/water (O/W) systems containing sodium dodecyl sulfate (SDS), n-pentanol, NaCl, cyclohexane, and water. The systems contained only small amounts of SDS (mostly

  5. Calculation of interfacial tensions with gradient theory. I. Pure and Pseudo-Pure Fluids. II. Binary Systems

    DEFF Research Database (Denmark)

    Zuo, You-Xiang; Stenby, Erling Halfdan

    1997-01-01

    In this research work, the gradient theory (GT) of inhomogeneous fluids was used to calculate interfacial tensions (IFTs). The correlations of the influence parameter are presented for pure hydrocarbons, which can improve the scaling behavior of pure fluids under near-critical conditions. The ove...

  6. Viscous Fingering on an Immiscible Reactive Interface with Variation of Interfacial Tension

    Science.gov (United States)

    Tsuzuki, Reiko; Nagatsu, Yuichiro; Li, Qian; Chen, Ching-Yao

    2017-11-01

    The effects of chemical reaction, in which surfactants are produced on the interface of two immiscible fluids, on viscous fingering in a radial Hele-Shaw flow are numerically investigated. The presence of surfactants reduces interfacial tension, which is an important factor to the fingering pattern formation. In the present study, influences of reaction rate and dispersion of produced surfactants, represented respectively by dimensionless parameters of Damkohler number and Peclet number, are evaluated systematically. Secondary fingering instability, e.g., tip-splitting and side-branching, is triggered by chemical reactions. Weaker surface tension generally induces tip-splitting. For the case of high Damkohler number, because of the vortex pairs generated within each finger, surfactant tends to accumulate significantly on the side of finger, so that side-branching is preferred. Nevertheless, side-branching is suppressed in the cases associated with low Peclet number, in which strong dispersion reduces the local variation of surfactant concentration. Considering the coupled effects by Damkohler number and Peclet number, the patterns obtained by the simulations qualitatively agree with the observations in the experiments.

  7. Field-theoretic simulations of block copolymer nanocomposites in a constant interfacial tension ensemble

    Science.gov (United States)

    Koski, Jason P.; Riggleman, Robert A.

    2017-04-01

    Block copolymers, due to their ability to self-assemble into periodic structures with long range order, are appealing candidates to control the ordering of functionalized nanoparticles where it is well-accepted that the spatial distribution of nanoparticles in a polymer matrix dictates the resulting material properties. The large parameter space associated with block copolymer nanocomposites makes theory and simulation tools appealing to guide experiments and effectively isolate parameters of interest. We demonstrate a method for performing field-theoretic simulations in a constant volume-constant interfacial tension ensemble (n V γ T ) that enables the determination of the equilibrium properties of block copolymer nanocomposites, including when the composites are placed under tensile or compressive loads. Our approach is compatible with the complex Langevin simulation framework, which allows us to go beyond the mean-field approximation. We validate our approach by comparing our n V γ T approach with free energy calculations to determine the ideal domain spacing and modulus of a symmetric block copolymer melt. We analyze the effect of numerical and thermodynamic parameters on the efficiency of the n V γ T ensemble and subsequently use our method to investigate the ideal domain spacing, modulus, and nanoparticle distribution of a lamellar forming block copolymer nanocomposite. We find that the nanoparticle distribution is directly linked to the resultant domain spacing and is dependent on polymer chain density, nanoparticle size, and nanoparticle chemistry. Furthermore, placing the system under tension or compression can qualitatively alter the nanoparticle distribution within the block copolymer.

  8. Field-theoretic simulations of block copolymer nanocomposites in a constant interfacial tension ensemble.

    Science.gov (United States)

    Koski, Jason P; Riggleman, Robert A

    2017-04-28

    Block copolymers, due to their ability to self-assemble into periodic structures with long range order, are appealing candidates to control the ordering of functionalized nanoparticles where it is well-accepted that the spatial distribution of nanoparticles in a polymer matrix dictates the resulting material properties. The large parameter space associated with block copolymer nanocomposites makes theory and simulation tools appealing to guide experiments and effectively isolate parameters of interest. We demonstrate a method for performing field-theoretic simulations in a constant volume-constant interfacial tension ensemble (nVγT) that enables the determination of the equilibrium properties of block copolymer nanocomposites, including when the composites are placed under tensile or compressive loads. Our approach is compatible with the complex Langevin simulation framework, which allows us to go beyond the mean-field approximation. We validate our approach by comparing our nVγT approach with free energy calculations to determine the ideal domain spacing and modulus of a symmetric block copolymer melt. We analyze the effect of numerical and thermodynamic parameters on the efficiency of the nVγT ensemble and subsequently use our method to investigate the ideal domain spacing, modulus, and nanoparticle distribution of a lamellar forming block copolymer nanocomposite. We find that the nanoparticle distribution is directly linked to the resultant domain spacing and is dependent on polymer chain density, nanoparticle size, and nanoparticle chemistry. Furthermore, placing the system under tension or compression can qualitatively alter the nanoparticle distribution within the block copolymer.

  9. Experimental density, viscosity, interfacial tension and water solubility of ethyl benzene-α-methyl benzyl alcohol–water system

    International Nuclear Information System (INIS)

    Barega, Esayas W.; Zondervan, Edwin; Haan, André B. de

    2013-01-01

    Highlights: • Properties were measured for MBA (methyl benzyl alcohol)-EB (ethyl benzene)-water. • MBA concentration was found to influence all the properties strongly. • The water solubility, density, and viscosity increased at high MBA concentration. • The interfacial tension decreased sharply at high MBA concentration. • MBA dictates the phase separation and mass transfer of the ternary system. -- Abstract: Density, viscosity, interfacial tension, and water solubility were measured for the (α-methyl benzyl alcohol (MBA) + Ethyl benzene (EB)) system at different concentrations of MBA in contact with water and sodium hydroxide solution (0.01 mol · kg −1 ) as aqueous phases. The properties were measured to identify the component which plays a governing role in changing the physical properties relevant to mass transfer and phase separation of the ternary system. The concentration of MBA was found to be the major factor influencing all the properties. The water solubility, the density, and the viscosity increased notably at higher concentrations of MBA; while, the interfacial tension decreased strongly. The use of 0.01 mol · kg −1 NaOH as an aqueous phase resulted in a decrease of the interfacial tension and a minor decrease in the water solubility. The density data were correlated using a quadratic mixing rule to describe the influence of concentration at any temperature. The viscosity data are correlated using the Nissan and Grunberg and Katti-Chaudhri equations. The Szyzkowski’s equation was used to correlate the interfacial tension data. The water solubility data were described using an exponential relationship. All the correlations described the experimental physical property data adequately

  10. Synthesis of ZnO nanoparticles for oil-water interfacial tension reduction in enhanced oil recovery

    Science.gov (United States)

    Soleimani, Hassan; Baig, Mirza Khurram; Yahya, Noorhana; Khodapanah, Leila; Sabet, Maziyar; Demiral, Birol M. R.; Burda, Marek

    2018-02-01

    Nanoparticles show potential use in applications associated with upstream oil and gas engineering to increase the performance of numerous methods such as wettability alteration, interfacial tension reduction, thermal conductivity and enhanced oil recovery operations. Surface tension optimization is an important parameter in enhanced oil recovery. Current work focuses on the new economical method of surface tension optimization of ZnO nanofluids for oil-water interfacial tension reduction in enhanced oil recovery. In this paper, zinc oxide (ZnO) nanocrystallites were prepared using the chemical route and explored for enhanced oil recovery (EOR). Adsorption of ZnO nanoparticles (NPs) on calcite (111) surface was investigated using the adsorption locator module of Materials Studio software. It was found that ZnO nanoparticles show maximum adsorption energy of - 253 kcal/mol. The adsorption of ZnO on the rock surface changes the wettability which results in capillary force reduction and consequently increasing EOR. The nanofluids have been prepared by varying the concentration of ZnO nanoparticles to find the optimum value for surface tension. The surface tension (ST) was calculated with different concentration of ZnO nanoparticles using the pendant drop method. The results show a maximum value of ST 35.57 mN/m at 0.3 wt% of ZnO NPs. It was found that the nanofluid with highest surface tension (0.3 wt%) resulted in higher recovery efficiency. The highest recovery factor of 11.82% at 0.3 wt% is due to the oil/water interfacial tension reduction and wettability alteration.

  11. Predicting CO2-H2O Interfacial Tension Using COSMO-RS

    DEFF Research Database (Denmark)

    Silvestri, Alessandro; Stipp, Susan Louise Svane; Andersson, Martin Peter

    2017-01-01

    Knowledge about the interaction between fluids and solids and the interfacial tension (IFT) that results is important for predicting behavior and properties in industrial systems and in nature, such as in rock formations before, during, and after CO2 injection for long-term storage. Many authors...... us interpret results and gain insight under conditions where experiments are difficult or impossible. Here, we report predictions for CO2–water interfacial tension performed using density functional theory (DFT) combined with the COSMO-RS implicit solvent model. We predicted the IFT dependence...... as a function of pressure (0–50 MPa), temperature (273–383 K), and salinity (0–5 M NaCl). The results agree well with literature data, within the estimated uncertainty for experiments and for molecular dynamics (MD) simulations, suggesting that the model can be used as a fast alternative to time-consuming...

  12. Origin of line tension for a Lennard-Jones nanodroplet

    NARCIS (Netherlands)

    Weijs, Joost; Weijs, Joost H.; Marchand, Antonin; Andreotti, Bruno; Lohse, Detlef; Snoeijer, Jacobus Hendrikus

    2011-01-01

    The existence and origin of line tension has remained controversial in literature. To address this issue, we compute the shape of Lennard-Jones nanodrops using molecular dynamics and compare them to density functional theory in the approximation of the sharp kink interface. We show that the

  13. Wettability of supercritical carbon dioxide/water/quartz systems: simultaneous measurement of contact angle and interfacial tension at reservoir conditions.

    Science.gov (United States)

    Saraji, Soheil; Goual, Lamia; Piri, Mohammad; Plancher, Henry

    2013-06-11

    Injection of carbon dioxide in deep saline aquifers is considered as a method of carbon sequestration. The efficiency of this process is dependent on the fluid-fluid and rock-fluid interactions inside the porous media. For instance, the final storage capacity and total amount of capillary-trapped CO2 inside an aquifer are affected by the interfacial tension between the fluids and the contact angle between the fluids and the rock mineral surface. A thorough study of these parameters and their variations with temperature and pressure will provide a better understanding of the carbon sequestration process and thus improve predictions of the sequestration efficiency. In this study, the controversial concept of wettability alteration of quartz surfaces in the presence of supercritical carbon dioxide (sc-CO2) was investigated. A novel apparatus for measuring interfacial tension and contact angle at high temperatures and pressures based on Axisymmetric Drop Shape Analysis with no-Apex (ADSA-NA) method was developed and validated with a simple system. Densities, interfacial tensions, and dynamic contact angles of CO2/water/quartz systems were determined for a wide range of pressures and temperatures relevant to geological sequestration of CO2 in the subcritical and supercritical states. Image analysis was performed with ADSA-NA method that allows the determination of both interfacial tensions and contact angles with high accuracy. The results show that supercritical CO2 alters the wettability of quartz surface toward less water-wet conditions compared to subcritical CO2. Also we observed an increase in the water advancing contact angles with increasing temperature indicating less water-wet quartz surfaces at higher temperatures.

  14. Wetting Transition and Line Tension of Oil on Water

    Science.gov (United States)

    Matsubara, H.; Aratono, M.

    Wetting has attracted wide attention in the field of applied chemistry because of its crucial importance in industrial operations such as coating, painting, and lubrication. Here, we summarize our fundamental understandings of surfactant-assisted wetting transitions which we have found and studied for the last ten years. The difference between the surfactant-assisted wetting transitions and existing ones is discussed. Moreover, the relation between wetting transitions and the stability of the three-phase contact line is examined in terms of the line tension of oil lenses.

  15. Investigation of oil recovery improvement by coupling an interfacial tension agent and a mobility control agent in light oil reservoirs. Second annual report, October 1993--September 1994

    Energy Technology Data Exchange (ETDEWEB)

    Pitts, M.J.

    1995-04-01

    {open_quotes}Investigation of Oil Recovery Improvement by Coupling an Interfacial Tension Agent and a Mobility Control Agent in Light Oil Reservoirs{close_quotes} is studying two major areas concerning co-injecting an interfacial tension reduction agent(s) and a mobility control agent. The first area defines the interactions of alkaline agents, surfactants, and polymers on a fluid-fluid and a fluid-rock basis. The second area concerns the economic improvement of the combined technology. This report continues the fluid-fluid interaction evaluations and begins the fluid-rock studies. Fluid-fluid interfacial tension work determined that replacing sodium ion with either potassium or ammonium ion in solutions with interfacial tension reduction up to 19,600 fold was detrimental and had little or no effect on alkali-surfactant solutions with interfacial tension reduction of 100 to 200 fold. Reservoir brine increases interfacial tension between crude oil and alkaline-surfactant solutions. Na{sub 2}CO{sub 3}-surfactant solutions maintained ultra low and low interfacial tension values better than NaOH-surfactant solutions. The initial phase of the fluid-rock investigations was adsorption studies. Surfactant adsorption is reduced when co-dissolved with alkali. Na{sub 2}CO{sub 3} and Na{sub 3}PO{sub 4} are more efficient at reducing surfactant adsorption than NaOH. When polymer is added to the surfactant solution, surfactant adsorption is reduced as well. When both polymer and alkali are added, polymer is the dominate component, reducing the Na{sub 2}CO{sub 3} and NaOH effect on adsorption. Substituting sodium ion with potassium or ammonium ion increased or decreased surfactant adsorption depending on surfactant structure with alkali having a less significant effect. No consistent change of surfactant adsorption with increasing salinity was observed in the presence or absence of alkali or polymer.

  16. Line Tension and Wettability of Nanodrops on Curved Surfaces.

    Science.gov (United States)

    Maheshwari, Shantanu; van der Hoef, Martin; Lohse, Detlef

    2016-01-12

    In this work we study the formation of nanodrops on curved surfaces (both convex and concave) by means of molecular dynamics simulations, where the particles interact via a Lennard-Jones potential. We find that the contact angle is not affected by the curvature of the substrate, in agreement with previous experimental findings. This means that the change in curvature of the drop in response to the change in curvature of the substrate can be predicted from simple geometrical considerations, under the assumption that the drop's shape is a spherical cap, and that the volume remains unchanged through the curvature. The resulting prediction is in perfect agreement with the simulation results, for both convex and concave substrates. In addition, we calculate the line tension, namely, by fitting the contact angle for different size drops to the modified Young equation. We find that the line tension for concave surfaces is larger than for convex surfaces, while for zero curvature it has a clear maximum. This feature is found to be correlated with the number of particles in the first layer of the liquid on the surface.

  17. Interfacial layers from the protein HFBII hydrophobin: Dynamic surface tension, dilatational elasticity and relaxation times

    NARCIS (Netherlands)

    Alexandrov, N.A.; Marinova, K.G.; Gurkov, T.D.; Danov, K.D.; Kralchevsky, P.A.; Stoyanov, S.D.; Blijdenstein, T.B.J.; Arnaudov, L.N.; Pelan, E.G.; Lips, A.

    2012-01-01

    The pendant-drop method (with drop-shape analysis) and Langmuir trough are applied to investigate the characteristic relaxation times and elasticity of interfacial layers from the protein HFBII hydrophobin. Such layers undergo a transition from fluid to elastic solid films. The transition is

  18. Simulation of Flow Behavior of Gas Condensate at Low Interfacial Tension

    DEFF Research Database (Denmark)

    Wang, Peng; Stenby, Erling Halfdan; Pope, Gary A.

    1996-01-01

    A vertical, long-core experiment of natural depletion of a gas condensate that was conducted by Elf Aquitaine is simulated by an equation-of-state (EOS) compositional simulator, UTCOMP. The Peng-Robinson (PR) EOS is used for phase-behavior calculation. Because of low interfactial tension (IFT) in...

  19. The interfacial surface tension of a quark-gluon plasma fireball in a ...

    Indian Academy of Sciences (India)

    surface tension with the cube of the critical transition temperature is in overall accordance with lattice QCD findings. ... critical radius Rc can be obtained by minimising (1) with respect to the droplet radius R, which in the .... QGP with suitable parametrisation to take care of the hydrodynamical (plasma) characteristics of the ...

  20. On the interfacial behavior of ionic liquids: surface tensions and contact angles.

    Science.gov (United States)

    Restolho, José; Mata, José L; Saramago, Benilde

    2009-12-01

    In this work the liquid/vapour and the solid/liquid interfaces of a series of ionic liquids: 1-ethyl-3-methylpyridinium ethyl sulfate, [EMPy][EtSO4], 1-ethyl-3-methylimidazolium ethyl sulfate, [EMIM][EtSO4], 1-ethanol-3-methylimidazolium tetrafluoroborate, [C2OHMIM][BF4], 1-butyl-3-methylimidazolium tetrafluoroborate, [BMIM][BF4], and 1-octyl-3-methylimidazolium tetrafluoroborate, [OMIM][BF4], were investigated. The surface tension was measured in a wide temperature range, (298-453) K. The contact angles were determined on substrates of different polarities. Both on the polar (glass) and the non-polar substrates ((poly-(tetrafluoroethylene) and poly-(ethylene)), the liquids with maximum and minimum surface tensions lead, respectively, to the highest and the lowest contact angles. The dispersive, gamma(L)(d), and non-dispersive, gamma(L)(nd), components of the liquid surface tension, gamma(L), were calculated from the contact angles on the non-polar substrates using the Fowkes approach. The polarity fraction, gamma(L)(nd)/gamma(L), was compared with the polarity parameter, k, obtained from the fitting of the surface tension vs. temperature data to the Eötvös equation. Good agreement was found for the extreme cases: [OMIM][BF4] exhibits the lowest polarity and [BMIM][BF4], the highest. When compared with the polarity fractions of standard liquids considered as "polar" liquids, the ionic liquids studied may be considered as moderately polar.

  1. The interfacial surface tension of a quark-gluon plasma fireball in a ...

    Indian Academy of Sciences (India)

    Department of Physics, Ramjas College, University of Delhi, Delhi 110 007, India. E-mail: drramanathan@vsnl.net ... independent of both the value of the transition temperature and the model parameters. Keywords. ..... the result is the independence of the QGP droplet surface tension σ to variations in the flow parameters of ...

  2. The interfacial tension of the mercury —1 M HClO4− solution interface at high potentials; comparison with double-layer capacitance measurements

    NARCIS (Netherlands)

    Sluyters-Rehbach, M.; Woittiez, W.J.A.; Sluyters, J.H.

    Interfacial tension values have been measured in order to calculate the electrical charge density as a function of potential. The results are in accordance with those obtained from double-layer capacitance data reported earlier2,3, also at highly positive potentials.

  3. Activity coefficients, interfacial tensions and retention in reversed-phase liquid chormatography on LiChrosorb RP-18 with methanol-water mixtures

    NARCIS (Netherlands)

    Hammers, W.E.; Meurs, G.J.; Ligny, C.L. de

    1982-01-01

    Literature data on activity coefficients of various solutes in water, of some tetraalkyl compounds in methanol-water mixture and of water in organic solvents have been correlated with the product of the molecular surface area of the solute and the solute-solvent interfacial tension at ambient

  4. The role of interfacial tension in colloid retention and remobilization during two-phase flow in a polydimethylsiloxane micro-model

    NARCIS (Netherlands)

    Zhang, Quilan; Hassanizadeh, S. Majid

    2017-01-01

    The work presented here consisted of steady-state and transient two-phase flow experiments on the role of interfacial tension in colloid transport. Experiments were performed in a polydimethylsiloxane (PDMS) micro-model containing a network of pores with a mean pore size of 30 µm. The flow network

  5. Influence of pH on Oil-Water Interfacial Tension and Mass Transfer for Asphaltenes Model Oils. Comparison with Crude Oil Behavior

    Directory of Open Access Journals (Sweden)

    Hutin Anthony

    2016-07-01

    Full Text Available Asphaltenes are shown to be amphoteric, containing acidic and basic species that can ionize at low and high pH respectively when they come in contact with water. We have used a mass transfer model in order to determine the partition coefficients of asphaltenes between oil and water. We have compared the influence of type of asphaltenes on interfacial tension and on mass transfer between oil and water and analysed the influence of an added surfactant. We have also compared the behavior of asphaltenes dissolved in model solvents with that of diluted heavy crude oils. Although asphaltenes qualitatively reproduce the behavior of crude oil components at the oil-water interface, differences were observed, either in interfacial tensions at low pH, or in partition coefficients at high pH. These differences are due to other molecules present in crude oil, which are either more interfacially active or more soluble in water.

  6. A finite-volume HLLC-based scheme for compressible interfacial flows with surface tension

    Energy Technology Data Exchange (ETDEWEB)

    Garrick, Daniel P. [Department of Aerospace Engineering, Iowa State University, Ames, IA (United States); Owkes, Mark [Department of Mechanical and Industrial Engineering, Montana State University, Bozeman, MT (United States); Regele, Jonathan D., E-mail: jregele@iastate.edu [Department of Aerospace Engineering, Iowa State University, Ames, IA (United States)

    2017-06-15

    Shock waves are often used in experiments to create a shear flow across liquid droplets to study secondary atomization. Similar behavior occurs inside of supersonic combustors (scramjets) under startup conditions, but it is challenging to study these conditions experimentally. In order to investigate this phenomenon further, a numerical approach is developed to simulate compressible multiphase flows under the effects of surface tension forces. The flow field is solved via the compressible multicomponent Euler equations (i.e., the five equation model) discretized with the finite volume method on a uniform Cartesian grid. The solver utilizes a total variation diminishing (TVD) third-order Runge–Kutta method for time-marching and second order TVD spatial reconstruction. Surface tension is incorporated using the Continuum Surface Force (CSF) model. Fluxes are upwinded with a modified Harten–Lax–van Leer Contact (HLLC) approximate Riemann solver. An interface compression scheme is employed to counter numerical diffusion of the interface. The present work includes modifications to both the HLLC solver and the interface compression scheme to account for capillary force terms and the associated pressure jump across the gas–liquid interface. A simple method for numerically computing the interface curvature is developed and an acoustic scaling of the surface tension coefficient is proposed for the non-dimensionalization of the model. The model captures the surface tension induced pressure jump exactly if the exact curvature is known and is further verified with an oscillating elliptical droplet and Mach 1.47 and 3 shock-droplet interaction problems. The general characteristics of secondary atomization at a range of Weber numbers are also captured in a series of simulations.

  7. Enhanced interfacial deformation in a Marangoni flow: A measure of the dynamical surface tension

    Science.gov (United States)

    Leite Pinto, Rodrigo; Le Roux, Sébastien; Cantat, Isabelle; Saint-Jalmes, Arnaud

    2018-02-01

    We investigate the flows and deformations resulting from the deposition of a water soluble surfactant at a bare oil-water interface. Once the surfactant is deposited, we show that the oil-water interface is deformed with a water bump rising upward into the oil. For a given oil, the maximal deformation—located at the surfactant deposition point—decreases with the oil-layer thickness. We also observe a critical oil-layer thickness below which the deformation becomes as large as the oil layer, leading to the rupture of this layer and an oil-water dewetting. Experimentally, it is found that this critical thickness depends on the oil density and viscosity. We then provide an analytical modelization that explains quantitatively all these experimental features. In particular, our analysis allows us to derive an analytical relationship between the vertical profile of the oil-water interface and the in-plane surface tension profile. Therefore, we propose that the monitoring of the interface vertical shape can be used as a new spatially resolved tensiometry technique.

  8. The non-ideal behaviour of the interfacial tension of the n-heptane + perfluoro-n-hexane mixture: A computational study

    Science.gov (United States)

    Dominguez, Hector

    2015-05-01

    Computer simulations of the n-heptane + perfluoro-n-hexane system is used to understand the unusual behaviour of the horizontal inflection of the vapour-liquid interfacial tension experiments of alkanes-perfluoroalkanes mixtures. Simulations are conducted and good agreement with experiments is obtained. From the results a change in curvature to a nearly constant value in the tensions at high perfluoro-n-hexane compositions is identified. Dynamic, thermodynamic and structural properties are analysed in that region and peculiar tendencies of those properties are found which help us to understand the nature of the uncommon inflection in the isotherms.

  9. The Snap Tension Analysis of Taut-Slack Mooring Line with tanh Method

    Directory of Open Access Journals (Sweden)

    Su-xia Zhang

    2017-01-01

    Full Text Available The continuous model is introduced, and the nonlinear partial differential equations of taut-slack mooring line system are transferred to nonlinear algebraic equations through tanh method, and four solitary solutions are obtained further. At the same time, to express the results clearly, the curve surfaces of strains, displacements, and tension are plotted. The results show that there are four different solutions in the system. With the pretension increasing, the tension changes from one solitary solution to snap tension, and when the pretension is increased further, the curve converts to continuous line, until straight line, which is corresponding to the taut mooring line. In the process of increasing of pretension, the mooring line transfers from slack to taut, accompanied with tension skipping, which is reduced by the system parameters, and different combination of parameters may introduce different tension in line, and the uncertainty may cause the breakage of mooring system. The results have an agreement with experiment, which shows that the calculating method in this paper may be believable and feasible. This work may provide reference for design of mooring system.

  10. Reduction of the electromagnetic radiation in high tension lines

    International Nuclear Information System (INIS)

    Araya Padilla, Eddie A.

    2006-01-01

    Introduces like the design of the transmission lines determine the profile of the electric and magnetic generated field. This profile is calculated with the use of the equations of Maxwell, and it depends rely on diverse geometries and operative factors of the line, so that an adequate physical distribution of the tower configuration, it could diminish the intensity of radiation generated inside of and in the border of right of way of the line. Pattern like the electric and magnetic generated fields are distributed satisfactorily, by means of the analysis of sensibility of parameters of design. (author) [es

  11. The Snap Tension Analysis of Taut-Slack Mooring Line with tanh Method

    OpenAIRE

    Su-xia Zhang; Rui-zhi Shi; Shengli Chen; Xi-jun Liu

    2017-01-01

    The continuous model is introduced, and the nonlinear partial differential equations of taut-slack mooring line system are transferred to nonlinear algebraic equations through tanh method, and four solitary solutions are obtained further. At the same time, to express the results clearly, the curve surfaces of strains, displacements, and tension are plotted. The results show that there are four different solutions in the system. With the pretension increasing, the tension changes from one soli...

  12. Line tension and morphology of a sessile droplet on a spherical substrate

    Science.gov (United States)

    Iwamatsu, Masao

    2016-05-01

    The effects of line tension on the morphology of a sessile droplet placed on top of a convex spherical substrate are studied. The morphology of the droplet is determined from the global minimum of the Helmholtz free energy. The contact angle between the droplet and the spherical substrate is expressed by the generalized Young's formula. When the line tension is positive and large, the contact angle jumps discontinuously to 180∘, the circular contact line shrinks towards the top of the substrate, and the droplet detaches from the substrate, forming a spherical droplet if the substrate is hydrophobic (i.e., the Young's contact angle is large). This finding is consistent with that predicted by Widom [J. Phys. Chem. 99, 2803 (1995), 10.1021/j100009a041]; the line tension induces a drying transition on a flat substrate. On the other hand, the contact angle jumps to 0∘, the circular contact line shrinks towards the bottom of the substrate, and the droplet spreads over the substrate to form a wrapped spherical droplet if the substrate is hydrophilic (i.e., the Young's contact angle is small). Therefore, not only the drying transition of a cap-shaped to a detached spherical droplet but also the wetting transition of a cap-shaped to a wrapped spherical droplet could occur on a spherical substrate as the surface area of the substrate is finite. When the line tension is negative and its magnitude increases, the contact line asymptotically approaches the equator from either above or below. The droplet with a contact line that coincides with the equator is an isolated, singular solution of the first variational problem. In this instance, the contact line is pinned and cannot move as far as the line tension is smaller than the critical magnitude, where the wetting transition occurs.

  13. Ezrin enhances line tension along transcellular tunnel edges via NMIIa driven actomyosin cable formation

    Science.gov (United States)

    Stefani, Caroline; Gonzalez-Rodriguez, David; Senju, Yosuke; Doye, Anne; Efimova, Nadia; Janel, Sébastien; Lipuma, Justine; Tsai, Meng Chen; Hamaoui, Daniel; Maddugoda, Madhavi P.; Cochet-Escartin, Olivier; Prévost, Coline; Lafont, Frank; Svitkina, Tatyana; Lappalainen, Pekka; Bassereau, Patricia; Lemichez, Emmanuel

    2017-06-01

    Transendothelial cell macroaperture (TEM) tunnels control endothelium barrier function and are triggered by several toxins from pathogenic bacteria that provoke vascular leakage. Cellular dewetting theory predicted that a line tension of uncharacterized origin works at TEM boundaries to limit their widening. Here, by conducting high-resolution microscopy approaches we unveil the presence of an actomyosin cable encircling TEMs. We develop a theoretical cellular dewetting framework to interpret TEM physical parameters that are quantitatively determined by laser ablation experiments. This establishes the critical role of ezrin and non-muscle myosin II (NMII) in the progressive implementation of line tension. Mechanistically, fluorescence-recovery-after-photobleaching experiments point for the upstream role of ezrin in stabilizing actin filaments at the edges of TEMs, thereby favouring their crosslinking by NMIIa. Collectively, our findings ascribe to ezrin and NMIIa a critical function of enhancing line tension at the cell boundary surrounding the TEMs by promoting the formation of an actomyosin ring.

  14. Dynamics of Surfactant Clustering at Interfaces and Its Influence on the Interfacial Tension: Atomistic Simulation of a Sodium Hexadecane-Benzene Sulfonate-Tetradecane-Water System.

    Science.gov (United States)

    Paredes, Ricardo; Fariñas-Sánchez, Ana Isabel; Medina-Rodrı Guez, Bryan; Samaniego, Samantha; Aray, Yosslen; Álvarez, Luis Javier

    2018-03-06

    The process of equilibration of the tetradecane-water interface in the presence of sodium hexadecane-benzene sulfonate is studied using intensive atomistic molecular dynamics simulations. Starting as an initial point with all of the surfactants at the interface, it is obtained that the equilibration time of the interface (several microseconds) is orders of magnitude higher than previously reported simulated times. There is strong evidence that this slow equilibration process is due to the aggregation of surfactants molecules on the interface. To determine this fact, temporal evolution of interfacial tension and interfacial formation energy are studied and their temporal variations are correlated with cluster formation. To study cluster evolution, the mean cluster size and the probability that a molecule of surfactant chosen at random is free are obtained as a function of time. Cluster size distribution is estimated, and it is observed that some of the molecules remain free, whereas the rest agglomerate. Additionally, the temporal evolution of the interfacial thickness and the structure of the surfactant molecules on the interface are studied. It is observed how this structure depends on whether the molecules agglomerate or not.

  15. Thermostability analysis of line-tension-associated nucleation at a gas-liquid interface

    Science.gov (United States)

    Singha, Sanat Kumar; Das, Prasanta Kumar; Maiti, Biswajit

    2017-01-01

    The influence of line tension on the thermostability of a droplet nucleated from an oversaturated vapor at the interface of the vapor and another immiscible liquid is investigated. Along with the condition of mechanical equilibrium, the notion of extremization of the reversible work of formation is considered to obtain the critical parameters related to heterogeneous nucleation. From the energetic formulation, the critical reversible work of formation is found to be greater than that of homogeneous nucleation for high value of the positive line tension. On the other hand, for high value of the negative line tension, the critical reversible work of formation becomes negative. Therefore, these thermodynamic instabilities under certain substrate wettability situations necessitate a free-energetics-based stability of the nucleated droplet, because the system energy is not minimized under these conditions. This thermostability is analogous to the transition-based stability proposed by Widom [B. Widom, J. Phys. Chem. 99, 2803 (1995)], 10.1021/j100009a041 in the case of partial wetting phenomena along with the positive line tension. The thermostability analysis limits the domain of the solution space of the present critical-value problem as the thermodynamic transformation in connection with homogeneous and workless nucleation is considered. Within the stability range of the geometry-based wetting parameters, three limiting modes of nucleation, i.e., total-dewetting-related homogeneous nucleation, and total-wetting-associated and total-submergence-associated workless nucleation scenarios, are identified. Either of the two related limiting wetting scenarios of workless nucleation, namely, total wetting and total submergence, is found to be favorable depending on the geometry-based wetting conditions. The line-tension-associated nucleation on a liquid surface can be differentiated from that on a rigid substrate, as in the former, the stability based on mechanical

  16. Apparent Contact Angle and Triple-Line Tension of a Soap Bubble on a Substrate.

    Science.gov (United States)

    Rodrigues, João Filipe; Saramago, Benilde; Fortes, Manuel Amaral

    2001-07-15

    The contact angle, θ, of a small bubble on a flat solid substrate was measured as a function of bubble radius, R. The observed deviation of the contact angle from 90 degrees can be accounted for in terms of a negative line tension, tau. The measured values of |tau|/gamma(f), where gamma(f) is the film tension, ranged between 0.15 and 0.6 mm and are proportional to the height, h, of the Plateau border, with |tau| congruent with1.7gamma(f)h. Copyright 2001 Academic Press.

  17. Local pressure components and interfacial tensions of a liquid film in the vicinity of a solid surface with a nanometer-scale slit pore obtained by the perturbative method.

    Science.gov (United States)

    Fujiwara, K; Shibahara, M

    2015-03-07

    A classical molecular dynamics simulation was conducted for a liquid-solid interfacial system with a nanometer-scale slit pore in order to reveal local thermodynamic states: local pressure components and interfacial tensions of a liquid film in the vicinity of the slit. The simulation also examined the transition mechanism between the two states of the liquid film: (a) liquid film on the slit and (b) liquid film in the slit, based on the local thermodynamic quantities from a molecular point of view. An instantaneous expression of the local pressure components and interfacial tensions, which is based on a volume perturbation, was presented to investigate time-dependent phenomena in molecular dynamics simulations. The interactions between the particles were described by the 12-6 Lennard-Jones potential, and effects of the fluid-solid interaction intensity on the local pressure components and interfacial tensions of the fluid in the vicinity of the slit were examined in detail by the presented perturbative method. The results revealed that the local pressure components tangential to the solid surface in the vicinity of the 1st fluid layer from the solid surface are different in a two dimensional plane, and the difference became pronounced in the vicinity of the corner of the slit, for cases where the fluid-solid interaction intensities are relatively strong. The results for the local interfacial tensions of the fluid inside the slit suggested that the local interfacial tensions in the vicinity of the 2nd and 3rd layers of the solid atoms from the entrance of the slit act as a trigger for the transition between the two states under the influence of a varying fluid-solid interaction.

  18. Interfacial tension phenomenon and mass transfer process in the reservoir brine-CO{sub 2} system at high pressures and elevated temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Yang, D.; Tontiwachwuthikul, P.; Gu, Y. [Petroleum Technology Research Centre, Regina, SK (Canada)]|[Regina Univ., SK (Canada)

    2005-07-01

    One of the potential technologies for mitigating greenhouse gas (GHG) emissions is the geological sequestration of anthropologic carbon dioxide (CO{sub 2}) in depleted oil or gas reservoirs or in saline aquifers. The interfacial interactions between CO{sub 2} and the crude oil, brine and reservoir minerals determine the success of sequestration. These interfacial interactions also influence the mass transfer of CO{sub 2} in the reservoir brine. This study developed an experimental technique to examine the mass transfer processes between the reservoir brine and CO{sub 2}. It also examined the dynamic interfacial tension (IFT) phenomenon of the reservoir brine-CO{sub 2} system under practical reservoir conditions and evaluated the temperatures, based on the axisymmetric drop shape analysis for the pendant drop case. The dynamic and equilibrium IFTs between the reservoir brine and CO{sub 2} were measured at different pressures and 2 constant temperatures. Several key physical phenomena were observed after the fresh brine phase made contact with the CO{sub 2}. The dynamic IFT was found to reduce gradually to a constant value referred to as the equilibrium IFT. This reduction is due to the adsorption of the CO{sub 2} molecules and the reorientation of water molecules at the pendant brine drop surface. The equilibrium IFT decreases with increasing pressure, but it increases as the temperature increases. A two-way mass transfer between the brine phase and CO{sub 2} was observed. It was concluded that the accurate determination of the maximum amount of CO{sub 2} that can be sequestered in a depleted reservoir or saline aquifer may depend on the two-way mass transfer between the reservoir brine and the carbon dioxide. 24 refs., 7 figs.

  19. Interfacial Tension in the CaO-Al2O3-SiO2-(MgO) Liquid Slag-Solid Oxide Systems

    Science.gov (United States)

    Abdeyazdan, Hamed; Monaghan, Brian J.; Longbottom, Raymond J.; Rhamdhani, M. Akbar; Dogan, Neslihan; Chapman, Michael W.

    2017-08-01

    Interfacial phenomenon is critical in metal processing and refining. While it is known to be important, there are little data available for key oxide systems in the literature. In this study, the interfacial tension ( σ LS) of liquid slag on solid oxides (alumina, spinel, and calcium aluminate), for a range of slags in the CaO-Al2O3-SiO2-(MgO) system at 1773 K (1500 °C), has been evaluated. The results show that basic ladle-type slags exhibit lower σ LS with oxide phases examined compared to that of acid tundish-type slags. Also, within the slag types (acid and base), σ LS was observed to decrease with increasing slag basicity. A correlation between σ LS and slag structure was observed, i.e., σ LS was found to decrease linearly with increasing of slag optical basicity (Λ) and decrease logarithmically with decreasing of slag viscosity from acid to base slags. This indicated a higher σ LS as the ions in the slag become larger and more complex. Through a work of adhesion ( W) analysis, it was shown that basic ladle slags with lower σ LS result in a greater W, i.e., form a stronger bond with the solid oxide phases examined. This indicates that all other factors being equal, the efficiency of inclusion removal from steel of inclusions of similar phase to these solid oxides would be greater.

  20. Line Tension and Interaction Energies of Membrane Rafts Calculated from Lipid Splay and Tilt

    OpenAIRE

    Kuzmin, Peter I.; Akimov, Sergey A.; Chizmadzhev, Yuri A.; Zimmerberg, Joshua; Cohen, Fredric S.

    2004-01-01

    Membrane domains known as rafts are rich in cholesterol and sphingolipids, and are thought to be thicker than the surrounding membrane. If so, monolayers should elastically deform so as to avoid exposure of hydrophobic surfaces to water at the raft boundary. We calculated the energy of splay and tilt deformations necessary to avoid such hydrophobic exposure. The derived value of energy per unit length, the line tension γ, depends on the elastic moduli of the raft and the surrounding membrane;...

  1. Comparação entre o método da gota pendente e o método da gota girante para medida da tensão interfacial entre polímeros Comparison between the pendant drop and spinning drop method to measure interfacial tension between polymers

    Directory of Open Access Journals (Sweden)

    Nicole R. Demarquette

    1997-09-01

    Full Text Available Dois instrumentos, um deles baseado no princípio da gota pendente e o outro baseado no método da gota girante, para medir a tensão interfacial entre polímeros, são apresentados e comparados aqui. Com ambos instrumentos foi possível visualizar a gota de polímero "on line". Os instrumentos mostraram-se complementares quanto às suas áreas de aplicação. O método da gota pendente deve ser usado quando as quantidades de polímero são limitadas ou quando o polímero mais denso é opaco. O método da gota girante deve ser usado quando a degradação térmica pode ser um problema ou quando o polímero menos denso é opaco.In this paper two apparatuses, one based on the principle of the pendant drop method and one based on the principle of the spinning drop are presented and compared. With both apparatuses it was possible to view the drop in real time and calculate the interfacial tension on-line. The two equipments were shown to be complementary in their use. The pendant drop method should be used when there are limited quantities of polymer and/or the denser polymer is opaque. The spinning drop method should be used when thermal degradation could be a problem and/or when the lighter polymer is opaque.

  2. Phases, line tension and pattern formation in molecularly thin films at the air-water interface

    Science.gov (United States)

    Mandal, Pritam

    A Langmuir film, which is a molecularly thin insoluble film on a liquid substrate, is one practical realization of a quasi-two dimensional matter. The major advantages of this system for the study of phase separation and phase co-existence are (a) it allows accurate control of the components and molecular area of the film and (b) it can be studied by various methods that require very flat films. Phase separation in molecularly thin films plays an important role in a range of systems from biomembranes to biosensors. For example, phase-separated lipid nano-domains in biomembranes are thought to play crucial roles in membrane function. I use Brewster Angel Microscopy (BAM) coupled with Fluorescence Microscopy (FM) and static Light Scattering Microscopy (LSM) to image phases and patterns within Langmuir films. The three microscopic techniques --- BAM, FM and LSM --- are complimentary to each other, providing distinct sets of information. They allow direct comparison with literature results in lipid systems. I have quantitatively validated the use of detailed hydrodynamic simulations to determine line tension in monolayers. Line tension decreases as temperature rises. This decrease gives us information on the entropy associated with the line, and thus about line structure. I carefully consider the thermodynamics of line energy and entropy to make this connection. In the longer run, LSM will be exploited to give us further information about line structure. I have also extended the technique by testing it on domains within the curved surface of a bilayer vesicle. I also note that in the same way that the presence of surface-active agents, known as surfactants, affects surface energy, the addiction of line active agents alters the inter-phase line energy. Thus my results set to stage to systematically study the influence of line active agents ---'linactants' --- on the inter-phase line energy. Hierarchal self-assembled chiral patterns were observed as a function of

  3. Density, refractive index, interfacial tension, and viscosity of ionic liquids [EMIM][EtSO4], [EMIM][NTf2], [EMIM][N(CN)2], and [OMA][NTf2] in dependence on temperature at atmospheric pressure.

    Science.gov (United States)

    Fröba, Andreas P; Kremer, Heiko; Leipertz, Alfred

    2008-10-02

    The density, refractive index, interfacial tension, and viscosity of ionic liquids (ILs) [EMIM][EtSO 4] (1-ethyl-3-methylimidazolium ethylsulfate), [EMIM][NTf 2] (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide), [EMIM][N(CN) 2] (1-ethyl-3-methylimidazolium dicyanimide), and [OMA][NTf 2] (trioctylmethylammonium bis(trifluoromethylsulfonyl)imide) were studied in dependence on temperature at atmospheric pressure both by conventional techniques and by surface light scattering (SLS). A vibrating tube densimeter was used for the measurement of density at temperatures from (273.15 to 363.15) K and the results have an expanded uncertainty ( k = 2) of +/-0.02%. Using an Abbe refractometer, the refractive index was measured for temperatures between (283.15 and 313.15) K with an expanded uncertainty ( k = 2) of about +/-0.0005. The interfacial tension was obtained from the pendant drop technique at a temperature of 293.15 K with an expanded uncertainty ( k = 2) of +/-1%. For higher and lower temperatures, the interfacial tension was estimated by an adequate prediction scheme based on the datum at 293.15 K and the temperature dependence of density. For the ILs studied within this work, at a first order approximation, the quantity directly accessible by the SLS technique was the ratio of surface tension to dynamic viscosity. By combining the experimental results of the SLS technique with density and interfacial tension from conventional techniques, the dynamic viscosity could be obtained for temperatures between (273.15 and 333.15) K with an estimated expanded uncertainty ( k = 2) of less than +/-3%. The measured density, refractive index, and viscosity are represented by interpolating expressions with differences between the experimental and calculated values that are comparable with but always smaller than the expanded uncertainties ( k = 2). Besides a comparison with the literature, the influence of structural variations on the thermophysical properties of the

  4. Studi Pengaruh Gerak Semi-submersible Drilling Rig dengan Variasi Pre-tension Mooring Line terhadap Keamanan Drilling Riser

    Directory of Open Access Journals (Sweden)

    Arda Arda

    2012-09-01

    Full Text Available Analisis terhadap sistem tambat pada anjungan pengeboran semi-submersible drilling rig perlu dilakukan sebelum dilakukannya operasi di lapangan untuk mengetahui perencanaan sistem tambat yang tepat dan aman. Dalam penelitian ini dilakukan analisa perilaku gerak semi-submersible dengan variasi pre-tension mooring line untuk mengetahui berapa besar pre-tension minimal yang harus digunakan agar operasi pengeboran di lingkungan laut Natuna dapat berjalan dengan aman. Variasi pre-tension yang digunakan adalah sebesar 400kN-2000kN dengan penambahan sebesar 400kN. Karakteristik gerakan semi-submersible diprediksi dengan menghitung RAO free floating dengan pemodelan numerik dalam domain frekuensi. Kemudian dilakukan analisa simulasi sistem lengkap (platform, mooring dan drilling riser dengan pemodelan numerik dalam domain waktu. Hasil yang didapat yakni nilai maksimum tegangan mooring line memenuhi batas kriteria API-RP2SK untuk semua variasi pre-tension dengan safety factor terkecil 2.44. Sudut flex joint drilling riser yang terjadi melewati batas kriteria API-RP16Q pada pre-tension 400kN-800kN yang mencapai 6.20 untuk sudut maksimum dan 4.80 untuk sudut rata-rata. Tegangan von Mises yang terjadi pada drilling riser melebihi kriteria API-RP16Q pada pre-tension 400kN-1200kN karena nilainya mencapai 369 MPa (0.82 yield stress.

  5. On the physically based modeling of surface tension and moving contact lines with dynamic contact angles on the continuum scale

    NARCIS (Netherlands)

    Huber, M.; Keller, F.; Säckel, W.; Hirschler, M.; Kunz, P.; Hassanizadeh, S.M.; Nieken, U.

    2016-01-01

    The description of wetting phenomena is a challenging problem on every considerable length-scale. The behavior of interfaces and contact lines on the continuum scale is caused by intermolecular interactions like the Van der Waals forces. Therefore, to describe surface tension and the resulting

  6. Biosurfactant as an Enhancer of Geologic Carbon Storage: Microbial Modification of Interfacial Tension and Contact Angle in Carbon dioxide/Water/Quartz Systems

    Directory of Open Access Journals (Sweden)

    Taehyung Park

    2017-07-01

    Full Text Available Injecting and storing of carbon dioxide (CO2 in deep geologic formations is considered as one of the promising approaches for geologic carbon storage. Microbial wettability alteration of injected CO2 is expected to occur naturally by microorganisms indigenous to the geologic formation or microorganisms intentionally introduced to increase CO2 storage capacity in the target reservoirs. The question as to the extent of microbial CO2 wettability alteration under reservoir conditions still warrants further investigation. This study investigated the effect of a lipopeptide biosurfactant—surfactin, on interfacial tension (IFT reduction and contact angle alteration in CO2/water/quartz systems under a laboratory setup simulating in situ reservoir conditions. The temporal shifts in the IFT and the contact angle among CO2, brine, and quartz were monitored for different CO2 phases (3 MPa, 30°C for gaseous CO2; 10 MPa, 28°C for liquid CO2; 10 MPa, 37°C for supercritical CO2 upon cultivation of Bacillus subtilis strain ATCC6633 with induced surfactin secretion activity. Due to the secreted surfactin, the IFT between CO2 and brine decreased: from 49.5 to 30 mN/m, by ∼39% for gaseous CO2; from 28.5 to 13 mN/m, by 54% for liquid CO2; and from 32.5 to 18.5 mN/m, by ∼43% for supercritical CO2, respectively. The contact angle of a CO2 droplet on a quartz disk in brine increased: from 20.5° to 23.2°, by 1.16 times for gaseous CO2; from 18.4° to 61.8°, by 3.36 times for liquid CO2; and from 35.5° to 47.7°, by 1.34 times for supercritical CO2, respectively. With the microbially altered CO2 wettability, improvement in sweep efficiency of injected and displaced CO2 was evaluated using 2-D pore network model simulations; again the increment in sweep efficiency was the greatest in liquid CO2 phase due to the largest reduction in capillary factor. This result provides novel insights as to the role of naturally occurring biosurfactants in CO2 storage and

  7. The tension adjuster used at the work line of electron beam radiation cross-linking wire and cable

    International Nuclear Information System (INIS)

    Zhang Yingfa; Liu Zhenhao; Yin Xuejun

    1999-01-01

    The tension adjuster is an important equipment in the transport system at the work line of electron beam radiation cross-linking wire and cable to realize the velocity synchronism. There are many kinds of the adjuster. By putting various adjusters together properly, the authors can keep the line work stable and raise the quality of the product. Two kinds of standing adjuster and their mechanism are introduced. Also the corresponding figures and formulas are shown

  8. Implicit mesh discontinuous Galerkin methods and interfacial gauge methods for high-order accurate interface dynamics, with applications to surface tension dynamics, rigid body fluid-structure interaction, and free surface flow: Part II

    Science.gov (United States)

    Saye, Robert

    2017-09-01

    In this two-part paper, a high-order accurate implicit mesh discontinuous Galerkin (dG) framework is developed for fluid interface dynamics, facilitating precise computation of interfacial fluid flow in evolving geometries. The framework uses implicitly defined meshes-wherein a reference quadtree or octree grid is combined with an implicit representation of evolving interfaces and moving domain boundaries-and allows physically prescribed interfacial jump conditions to be imposed or captured with high-order accuracy. Part one discusses the design of the framework, including: (i) high-order quadrature for implicitly defined elements and faces; (ii) high-order accurate discretisation of scalar and vector-valued elliptic partial differential equations with interfacial jumps in ellipticity coefficient, leading to optimal-order accuracy in the maximum norm and discrete linear systems that are symmetric positive (semi)definite; (iii) the design of incompressible fluid flow projection operators, which except for the influence of small penalty parameters, are discretely idempotent; and (iv) the design of geometric multigrid methods for elliptic interface problems on implicitly defined meshes and their use as preconditioners for the conjugate gradient method. Also discussed is a variety of aspects relating to moving interfaces, including: (v) dG discretisations of the level set method on implicitly defined meshes; (vi) transferring state between evolving implicit meshes; (vii) preserving mesh topology to accurately compute temporal derivatives; (viii) high-order accurate reinitialisation of level set functions; and (ix) the integration of adaptive mesh refinement. In part two, several applications of the implicit mesh dG framework in two and three dimensions are presented, including examples of single phase flow in nontrivial geometry, surface tension-driven two phase flow with phase-dependent fluid density and viscosity, rigid body fluid-structure interaction, and free

  9. Implicit mesh discontinuous Galerkin methods and interfacial gauge methods for high-order accurate interface dynamics, with applications to surface tension dynamics, rigid body fluid-structure interaction, and free surface flow: Part I

    Science.gov (United States)

    Saye, Robert

    2017-09-01

    In this two-part paper, a high-order accurate implicit mesh discontinuous Galerkin (dG) framework is developed for fluid interface dynamics, facilitating precise computation of interfacial fluid flow in evolving geometries. The framework uses implicitly defined meshes-wherein a reference quadtree or octree grid is combined with an implicit representation of evolving interfaces and moving domain boundaries-and allows physically prescribed interfacial jump conditions to be imposed or captured with high-order accuracy. Part one discusses the design of the framework, including: (i) high-order quadrature for implicitly defined elements and faces; (ii) high-order accurate discretisation of scalar and vector-valued elliptic partial differential equations with interfacial jumps in ellipticity coefficient, leading to optimal-order accuracy in the maximum norm and discrete linear systems that are symmetric positive (semi)definite; (iii) the design of incompressible fluid flow projection operators, which except for the influence of small penalty parameters, are discretely idempotent; and (iv) the design of geometric multigrid methods for elliptic interface problems on implicitly defined meshes and their use as preconditioners for the conjugate gradient method. Also discussed is a variety of aspects relating to moving interfaces, including: (v) dG discretisations of the level set method on implicitly defined meshes; (vi) transferring state between evolving implicit meshes; (vii) preserving mesh topology to accurately compute temporal derivatives; (viii) high-order accurate reinitialisation of level set functions; and (ix) the integration of adaptive mesh refinement. In part two, several applications of the implicit mesh dG framework in two and three dimensions are presented, including examples of single phase flow in nontrivial geometry, surface tension-driven two phase flow with phase-dependent fluid density and viscosity, rigid body fluid-structure interaction, and free

  10. Formation et stabilisation des émulsions inverses eau de mer-pétrole. Rôle de la tension et de la viscosité d'interface Formation and Stabilization of Reverse Seawater-Oil Emulsions. Role of Tension and Interfacial Viscosity

    Directory of Open Access Journals (Sweden)

    Desmaison M.

    2006-11-01

    Full Text Available On a étudié l'évolution au cours du temps de la tension et de la viscosité à l'interface d'un pétrole brut arabe léger et d'eau de mer reconstituée. D'une valeur initiale moyenne de 18 mNm-1, la tension interfaciale s'abaisse au niveau de 1 mNm-1 après 40 jours de contact. L'influence de l'oxygène et de la lumière, l'action des antioxydants et le rôle des constituants isolés du pétrole montrent que cette évolution est due à une oxydation photochimique de composés de la fraction aromatique. Inversement, la viscosité interfaciale augmente avec le temps selon une allure exponentielle. Cette évolution est liée à la présence d'asphaltènes dont les structures s'organisent au cours du temps. La superposition de ces deux phénomènes entraîne la formation et la stabilisation des émulsions inverses, dites mousses au chocolat que l'on observe lors des déversements accidentels de pétrole en mer. This article examines the evolution in time of the tension and interfacial viscosity of the Arabian Light crude oil reconstituted seawater interface. From an initial level of 18 mNm-1, the interfacial tension decreases to 1 mNm-1 after 40 days of contact. The influence of oxygen and light, the effect of antioxidants and the rote of constituents isolated from the oil show that this evolution is due to photochemical oxidation of compounds in the aromatic fraction. On the contrary, interfacial viscosity increases at an exponential rate with time. This evolution is linked to the presence of asphaltenes having structures which become organized with time. The combined effect of these two phenomena causes the formation and stabilization of reverse emulsions, called chocolate mousse, which are seen during accidental offshore oil spills.

  11. Development of a Front Tracking Method for Two-Phase Micromixing of Incompressible Viscous Fluids with Interfacial Tension in Solvent Extraction

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Yijie [ORNL; Lim, Hyun-Kyung [ORNL; de Almeida, Valmor F [ORNL; Navamita, Ray [State University of New York, Stony Brook; Wang, Shuqiang [State University of New York, Stony Brook; Glimm, James G [ORNL; Li, Xiao-lin [State University of New York, Stony Brook; Jiao, Xiangmin [ORNL

    2012-06-01

    This progress report describes the development of a front tracking method for the solution of the governing equations of motion for two-phase micromixing of incompressible, viscous, liquid-liquid solvent extraction processes. The ability to compute the detailed local interfacial structure of the mixture allows characterization of the statistical properties of the two-phase mixture in terms of droplets, filaments, and other structures which emerge as a dispersed phase embedded into a continuous phase. Such a statistical picture provides the information needed for building a consistent coarsened model applicable to the entire mixing device. Coarsening is an undertaking for a future mathematical development and is outside the scope of the present work. We present here a method for accurate simulation of the micromixing dynamics of an aqueous and an organic phase exposed to intense centrifugal force and shearing stress. The onset of mixing is the result of the combination of the classical Rayleigh- Taylor and Kelvin-Helmholtz instabilities. A mixing environment that emulates a sector of the annular mixing zone of a centrifugal contactor is used for the mathematical domain. The domain is small enough to allow for resolution of the individual interfacial structures and large enough to allow for an analysis of their statistical distribution of sizes and shapes. A set of accurate algorithms for this application requires an advanced front tracking approach constrained by the incompressibility condition. This research is aimed at designing and implementing these algorithms. We demonstrate verification and convergence results for one-phase and unmixed, two-phase flows. In addition we report on preliminary results for mixed, two-phase flow for realistic operating flow parameters.

  12. Emulsions for interfacial filtration.

    Energy Technology Data Exchange (ETDEWEB)

    Grillet, Anne Mary; Bourdon, Christopher Jay; Souza, Caroline Ann; Welk, Margaret Ellen; Hartenberger, Joel David; Brooks, Carlton, F.

    2006-11-01

    We have investigated a novel emulsion interfacial filter that is applicable for a wide range of materials, from nano-particles to cells and bacteria. This technology uses the interface between the two immiscible phases as the active surface area for adsorption of targeted materials. We showed that emulsion interfaces can effectively collect and trap materials from aqueous solution. We tested two aqueous systems, a bovine serum albumin (BSA) solution and coal bed methane produced water (CBMPW). Using a pendant drop technique to monitor the interfacial tension, we demonstrated that materials in both samples were adsorbed to the liquid-liquid interface, and did not readily desorb. A prototype system was built to test the emulsion interfacial filter concept. For the BSA system, a protein assay showed a progressive decrease in the residual BSA concentration as the sample was processed. Based on the initial prototype operation, we propose an improved system design.

  13. Effect of Added Surfactants on the Dynamic Interfacial Tension Behaviour of Alkaline/Diluted Heavy Crude Oil System Effet de l’ajout de tensioactifs sur le comportement dynamique de la tension interfaciale du système solution alcaline/brut dilué

    Directory of Open Access Journals (Sweden)

    Trabelsi S.

    2013-02-01

    Full Text Available This study has been undertaken to get a better understanding of the interactions between Enhanced Oil Recovery (EOR surfactants used in chemical flooding and in situ surfactants present in an heavy oil. We report an experimental study of dynamic Interfacial Tension (IFT behaviour of diluted heavy oil/surfactant enhanced-alkaline systems. The dynamic IFT was measured using pendant drop and spinning drop tensiometers. The dynamic IFT between diluted heavy oil and alkaline solution (pH 11 with no added surfactant increased sharply with time, which was attributed to the transfer of the in situ surfactant (produced by saponification of the acids groups present in the crude oil across the oil/water interface. The addition of Sodium Dodecyl Benzene Sulfonate (SDBS above the Critical Micellar Concentration (CMC ~ 0.002%, changed completely the dynamic IFT behaviour of the diluted heavy oil as the IFT strongly decreased and finally reached a plateau, of about 1.5 × 10-3 mN/m at a concentration of only 0.02%. We attributed the efficiency of SDBS to a synergistic effect between the in situ surfactant and the added surfactant that form a mixed interfacial monolayer, which is very efficient in decreasing the IFT to ultra low values and in resisting mass transfer across the oil/water interface. Cette étude a été réalisée pour mieux comprendre les interactions entre les tensioactifs utilisés pour la récupération assistée de pétrole et les tensioactifs in situ présents dans le brut. Nous expérimentons le comportement dynamique des tensions interfaciales (mesurées par les méthodes de goutte pendante et goutte tournante entre le brut lourd dilué et les solutions alcalines avec ajout de tensioactif. La tension interfaciale dynamique entre le brut dilué et une solution alcaline (pH 11 sans ajout de tensioactif croît fortement au cours du temps, cette augmentation est attribuée au transfert des tensioactifs in situ (produits par saponification des

  14. Optical trapping of colloidal particles and measurement of the defect line tension and colloidal forces in a thermotropic nematic liquid crystal

    International Nuclear Information System (INIS)

    Smalyukh, I.I.; Kuzmin, A.N.; Kachynski, A.V.; Prasad, P.N.; Lavrentovich, O.D.

    2005-01-01

    We demonstrate optical trapping and manipulation of transparent microparticles suspended in a thermotropic nematic liquid crystal with low birefringence. We employ the particle manipulation to measure line tension of a topologically stable disclination line and to determine colloidal interaction of particles with perpendicular surface anchoring of the director. The three-dimensional director fields and positions of the particles manipulated by laser tweezers are visualized by fluorescence confocal polarizing microscopy

  15. Construção e avaliação de célula de fluxo para estudo da tensão interfacial dinâmica da interface fluxo líquido - sólido por despolarização da fluorescência Development of a flow cell to study dynamic interfacial tension of solid-liquid flow by fluorescence depolarization

    Directory of Open Access Journals (Sweden)

    Martha T. P. O. Castro

    2005-03-01

    Full Text Available A simple low-cost flow cell was developed, built and optimized in order to observe dynamic interfacial tension of continuous flow systems. Distinct materials can be used in one of the cell walls in order to observe the intermolecular forces between the flowing liquid and the chemical constitution of the walls. The fluorescence depolarization was evaluated using Rhodamine B as fluorescent probe seeded in ethylene glycol. The effects of the positioning angles on the data acquired across the cell are reported. The reproducibility of the data was evaluated with a spectrometer assembled in-house and the relative standard deviation was below 3%.

  16. Walking a fine line: managing the tensions associated with medication non-adherence in an acute inpatient psychiatric setting.

    Science.gov (United States)

    Wijnveld, Anne-Marie; Crowe, Marie

    2010-05-01

    The aim of this study was to use a phenomenological methodology to examine mental health nurses' experiences of administering medications to patients who were non-adherent in an acute inpatient service. There is a large body of literature focused on exploring the issue of non-adherence to prescribed medication, but there is very little examining this from mental health nurses' perspectives. Many of the medications prescribed for patients diagnosed with a psychiatric disorder have serious side effects and limited efficacy. Mental health nurses in acute inpatient environments are regularly confronted with the difficulties inherent in the conflicting roles associated with the need to maintain therapeutic relationships and the expectation that they ensure patients take their medications. This is a qualitative study exploring mental health nurses' descriptions of managing medication adherence in an acute inpatient unit. The interpretive phenomenological methodology of Van Manen (Researching Lived Experience: Human Science for an Action Sensitive Pedagogy, 1990) was used in this study to capture the experiences of a group of nurses. This research process involves a dynamic interplay between the following six research activities: (1) turning to the nature of the lived experience; (2) investigating the experience as we live it; (3) reflecting on essential themes; (4) a description of the phenomenon through the art of writing and rewriting; (5) maintaining a strong and oriented pedagogical relation to the phenomenon; and (6) balancing the research context by considering parts and whole. Four themes emerged from the existential analysis that described the mental health nurses' experiences: doing the job for doctors (relationality); stopping and listening (temporality); stepping in (corporeality); and walking a fine line (spatiality). It is proposed that models of therapeutic interventions offering alternative or conjunctive treatment to medications could be incorporated into

  17. Evaluation of 8.0-cm needle at the fourth anterior axillary line for needle chest decompression of tension pneumothorax.

    Science.gov (United States)

    Chang, Samuel J; Ross, Samuel Wade; Kiefer, David J; Anderson, William E; Rogers, Amelia T; Sing, Ronald F; Callaway, David W

    2014-04-01

    Five-centimeter needles at the second intercostal space midclavicular line (2MCL) have high failure rates for decompression of tension pneumothorax. This study evaluates 8-cm needles directed at the fourth intercostal space anterior axillary line (4AAL). Retrospective radiographic analysis of 100 consecutive trauma patients 18 years or older from January to September 2011. Measurements of chest wall thickness (CWT) and depth to vital structure (DVS) were obtained at 2MCL and 4AAL. 4AAL measurements were taken based on two angles: closest vital structure and perpendicular to the chest wall. Primary outcome measures were radiographic decompression (RD) (defined as CWT RNI) (DVS > 80 mm) of 8-cm needles at 4AAL. Secondary outcome measures are effect of angle of entry on RNI at 4AAL, RD and RNI of 8-cm needles at 2MCL, and comparison of 5-cm needles with 8-cm needles at both locations. Eighty-four percent of the patients were male, with mean Injury Severity Score (ISS) of 17.7 (range, 1.0-66.0) and body mass index of 26.8 (16.5-48.4). Mean CWT at 4AAL ranged from 37.6 mm to 39.9 mm, significantly thinner than mean CWT at 2MCL (43.3-46.7 mm). Eight-centimeter needle RD was more than 96% at both 4AAL and 2MCL. Five-centimeter RD ranged from 66% to 81% at all sites. Mean DVS at 4AAL ranged from 91.8 mm to 128.0 mm. RNI at all sites was more than 91% except at left 4AAL, when taken to the closest vital structure (mean DVS, 91.8 mm), with 68% RNI. Perpendicular entry increased DVS to 109.4 mm and subsequent RNI to 91%. Five-centimeter RNI at all sites was more than 99%. CWT at 4AAL is significantly thinner than 2MCL. Based on radiographic measurements, 8-cm catheters have a higher chance of pleural decompression when compared with 5-cm catheters. Steeper angle of entry at 4AAL improves 8-cm noninjury rates to more than 91%. Therapeutic/care management study, level IV.

  18. Type of Material in the Pipes Overhead Power Lines Impact on the Distribution on the Size of the Overhang and the Tension

    Science.gov (United States)

    Pawlak, Urszula; Pawlak, Marcin

    2017-10-01

    The article presents the material type from which the conductors of the overhead power lines are produced influences on the size of the overhang and the tension. The aim of the calculations was to present the benefits of the mechanics of the cable resulting from the type of cable used. The analysis was performed for two types of cables: aluminium with steel core and aluminium with composite core, twice span power line section. 10 different conductor-to-strand coil, wind, icing, and temperature variations were included in the calculations. The string description was made by means of a chain curve, while the horizontal component H of the tension force was determined using the bisection method. The loads were collected in accordance with applicable Eurocode.

  19. Tension Headache

    Science.gov (United States)

    ... your head Tenderness on your scalp, neck and shoulder muscles Tension headaches are divided into two main categories — ... that monitor and give you feedback on body functions such as muscle tension, heart rate and blood pressure. You then ...

  20. Fundamentals of interfacial and colloid science Vol III: Liquid-fluid interfaces

    NARCIS (Netherlands)

    Lyklema, J.

    2000-01-01

    This volume deals with various aspects of surface tensions and interfacial tensions. Together with the phenomenon of adsorption (enrichment of molecules at interfaces), these tensions constitute the basic characteristics of interfaces. The authors try to keep the treatment systematic and deductive.

  1. Tension-saturated and unsaturated flows from line sources in subsurface irrigation: Riesenkampf's and Philip's solutions revisited

    Science.gov (United States)

    Kacimov, A. R.; Obnosov, Yu. V.

    2016-03-01

    Riesenkampf's (1938), R-38 (referred to here as R-38), analytical solution for steady 2-D flow from a buried line source in a homogeneous Green-Ampt soil, with a wetting plume bounded by a free surface (capillary fringe), is compared with Philip's (1969), (P-69), one for genuinely unsaturated wetting of Gardner's infinite-extension soil. Conformal mappings are used in R-38, from which we derived the flow net, pore-water isobars, isochrones, fields of Darcian velocity and resultant force acting on saturated porous skeleton, fine geometry (shape and size) of the constant-head contour encompassing a mole-emitter or leaky-pipe, as well as the dependence of the total discharge per unit pipe length on uniform pressure in the pipe, capillarity of the soil, radius of the pipe, and saturated hydraulic conductivity. An ovalic "water table" isobar, encompassing P-69 source, is compared with one of R-38 for a fixed discharge and saturated conductivity but adjusted sorptive numbers. The Whisler and Bouwer (1970) relation between the static height of capillary rise and sorptive number is shown to give a good match between R-38 and P-69 isobars. This allows to use R-38 in the source vicinity and P-69 in the far-field zone. Computer algebra (Mathematica) routines are used for visualization of the known and extended R-38 and P-69 solutions.

  2. Free-Energy Barrier of Filling a Spherical Cavity in the Presence of Line Tension: Implication to the Energy Barrier between the Cassie and Wenzel States on a Superhydrophobic Surface with Spherical Cavities.

    Science.gov (United States)

    Iwamatsu, Masao

    2016-09-20

    The free-energy barrier of filling a spherical cavity having an inner wall of various wettabilities is studied. The morphology and free energy of a lens-shaped droplet are determined from the minimum of the free energy. The effect of line tension on the free energy is also studied. Then, the equilibrium contact angle of the droplet is determined from the generalized Young's equation. By increasing the droplet volume within the spherical cavity, the droplet morphology changes from spherical with an equilibrium contact angle of 180° to a lens with a convex meniscus, where the morphological complete drying transition occurs. By further increasing the droplet volume, the meniscus changes from convex to concave. Then, the lens-shaped droplet with concave meniscus spreads over the whole inner wall, resulting in an equilibrium contact angle of 0° to leave a spherical bubble, where the morphological complete wetting transition occurs. Finally, the whole cavity is filled with liquid. The free energy shows a barrier from complete drying to complete wetting as a function of droplet volume, which corresponds to the energy barrier between the Cassie and Wenzel states of the superhydrophobic surface with spherical cavities. The free-energy maximum occurs when the meniscus of the droplet becomes flat, and it is given by an analytic formula. The effect of line tension is expressed by the scaled line tension, and this effect is largest at the free-energy maximum. The positive line tension increases the free-energy maximum, which thus increases the stability of the Cassie superhydrophobic state, whereas the negative line tension destabilizes the superhydrophobic state.

  3. Tension headache.

    Science.gov (United States)

    Ziegler, D K

    1978-05-01

    Headache is an extremely common symptom, and many headaches undoubtedly have a relationship to stressful situations. The clear definition, however, of a "tension headache" complex and its differentiation from migraine in some patients is difficult. The problems are in the identification of a specific headache pattern induced by stress or "tension" and the relationship of the symptom to involuntary contraction of neck and scalp muscles. Treatment consists of analgesics and occasionally mild tranquilizers. Psychotherapy consists of reassurance and often other supportive measures, including modification of life styles. Various feedback techniques have been reported of value, but their superiority to suggestion and hypnosis is still problematic.

  4. A Preliminary Investigation of the Interfacial and Dielectric Properties of Polyhedral Oligomeric Silsesquioxane Polymer Blends

    National Research Council Canada - National Science Library

    Chaffee, Kevin

    1998-01-01

    ...) have been investigated. POSS end-capping of a semiflexible liquid crystalline polymer lowers the interfacial tension between the parent liquid crystalline polymer (LCP) and poly(dimethyl siloxane) PDMS...

  5. Interfacial effects in multilayers

    International Nuclear Information System (INIS)

    Barbee, T.W. Jr.

    1998-01-01

    Interfacial structure and the atomic interactions between atoms at interfaces in multilayers or nano-laminates have significant impact on the physical properties of these materials. A technique for the experimental evaluation of interfacial structure and interfacial structure effects is presented and compared to experiment. In this paper the impact of interfacial structure on the performance of x-ray, soft x-ray and extreme ultra-violet multilayer optic structures is emphasized. The paper is concluded with summary of these results and an assessment of their implications relative to multilayer development and the study of buried interfaces in solids in general

  6. Interfacial Properties of Polydimethylsiloxane-Water Systems

    Science.gov (United States)

    Ismail, Ahmed E.; Grest, Gary S.; Stevens, Mark J.; Tsige, Mesfin; Heine, David R.

    2008-03-01

    Polydimethylsiloxane (PDMS) is a main constituent of silicone adhesives, which have a wide use as adhesives. Often these adhesives are used as sealants. The interaction between water and PDMS is of fundamental importance. To improve our understanding at the molecular level, we have performed molecular dynamics (MD) simulations of PDMS in the presence of water, with the long-term goal of studying how water molecules effect debonding at the surface. Knowledge of the basic interfacial properties of a multicomponent system, such as the surface tension, contact angle, and diffusion constant, are essential to obtain the proper dynamic behavior in a molecular simulation of adhesion and wetting processes. Explicit-atom simulations of 10^5 or more atoms were used to determine liquid-vapor surface tension and the contact angle for water on the surface of PDMS. We present results for the dependence of the surface tension on chain length and end-group functionality.

  7. Surface density profile and surface tension of the one-component classical plasma

    International Nuclear Information System (INIS)

    Ballone, P.; Senatore, G.; Trieste Univ.; Tosi, M.P.; Oxford Univ.

    1982-08-01

    The density profile and the interfacial tension of two classical plasmas in equilibrium at different densities are evaluated in the square-density-gradient approximation. For equilibrium in the absence of applied external voltage, the profile is oscillatory in the higher-density plasma and the interfacial tension is positive. The amplitude and phase of these oscillations and the magnitude of the interfacial tension are related to the width of the background profile. Approximate representations of the equilibrium profile by matching of its asymptotic forms are analyzed. A comparison with computer simulation data and a critical discussion of a local-density theory are also presented. (author)

  8. Interfacial Properties of an Ionic Liquid by Molecular Dynamics

    NARCIS (Netherlands)

    Heggen, B.; Zhao, W.; Leroy, F.; Dammers, A.T.; Müller-Plathe, F.

    2010-01-01

    We studied the influence of a liquid-vapor interface on dynamic properties like reorientation and diffusion as well as the surface tension of the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) by molecular dynamics simulations. In the interfacial region, reorientation of

  9. First-order and tricritical wetting transitions in the two-dimensional Ising model caused by interfacial pinning at a defect line.

    Science.gov (United States)

    Trobo, Marta L; Albano, Ezequiel V; Binder, Kurt

    2014-08-01

    We present a study of the critical behavior of the Blume-Capel model with three spin states (S=±1,0) confined between parallel walls separated by a distance L where competitive surface magnetic fields act. By properly choosing the crystal field (D), which regulates the density of nonmagnetic species (S=0), such that those impurities are excluded from the bulk (where D=-∞) except in the middle of the sample [where D(M)(L/2)≠-∞], we are able to control the presence of a defect line in the middle of the sample and study its influence on the interface between domains of different spin orientations. So essentially we study an Ising model with a defect line but, unlike previous work where defect lines in Ising models were defined via weakened bonds, in the present case the defect line is due to mobile vacancies and hence involves additional entropy. In this way, by drawing phase diagrams, i.e., plots of the wetting critical temperature (T(w)) versus the magnitude of the crystal field at the middle of the sample (D(M)), we observe curves of (first-) second-order wetting transitions for (small) high values of D(M). Theses lines meet in tricritical wetting points, i.e., (T(w)(tc),D(M)(tc)), which also depend on the magnitude of the surface magnetic fields. It is found that second-order wetting transitions satisfy the scaling theory for short-range interactions, while first-order ones do not exhibit hysteresis, provided that small samples are used, since fluctuations wash out hysteretic effects. Since hysteresis is observed in large samples, we performed extensive thermodynamic integrations in order to accurately locate the first-order transition points, and a rather good agreement is found by comparing such results with those obtained just by observing the jump of the order parameter in small samples.

  10. Interfacial properties of immiscible Co-Cu alloys

    DEFF Research Database (Denmark)

    Egry, I.; Ratke, L.; Kolbe, M.

    2010-01-01

    Using electromagnetic levitation under microgravity conditions, the interfacial properties of an Cu75Co25 alloy have been investigated in the liquid phase. This alloy exhibits a metastable liquid miscibility gap and can be prepared and levitated in a configuration consisting of a liquid cobalt......-rich core surrounded by a liquid copper-rich shell. Exciting drop oscillations and analysing the frequency spectrum, both surface and (liquid–liquid) interfacial tension can be derived from the observed oscillation frequencies. This paper briefly reviews the theoretical background and reports on a recent...

  11. Interfacial behavior of alkaline protease at the air-water and oil-water interfaces

    Science.gov (United States)

    Zhang, Jian; Li, Yanyan; Wang, Jing; Zhang, Yue

    2018-03-01

    The interfacial behavior of alkaline protease at the air-water and n-hexane-water interfaces was investigated using interfacial tension, dilatational rheology and dynamic light scattering. Additionally, different adsorption models which are Langmuir, Frumkin, Reorientation-A and Reorientation-R were used to fitting the data of equilibrium interfacial tension for further understanding the interfacial behavior of alkaline protease. Data fitting of the equilibrium interfacial tension was achieved by IsoFit software. The results show that the molecules arrangement of the alkaline protease at the n-hexane-water interface is more tightly than at the air-water interface. The data were further analyzed to indicate that the hydrophobic chains of alkaline protease penetrate into oil phase deeper than the air phase. Also data indicate that the electrostatic interactions and hydrophobic interactions at the n-hexane-water interface are stronger than at the air-water interface within molecules of the alkaline protease. Based on comprehensive analysis of the adsorption kinetics and interfacial rheological properties, interfacial structures mechanism of alkaline protease at n-hexane-water and air-water interfaces was proposed.

  12. Interfacial strength development in thermoplastic resins and fiber-reinforced thermoplastic composites

    Science.gov (United States)

    Howes, Jeremy C.; Loos, Alfred C.

    1987-01-01

    An experimental program to develop test methods to be used to characterize interfacial (autohesive) strength development in polysulfone thermoplastic resin and graphite-polysulfone prepreg during processing is reported. Two test methods were used to examine interfacial strength development in neat resin samples. These included an interfacial tension test and a compact tension (CT) fracture toughness test. The interfacial tensile test proved to be very difficult to perform with a considerable amount of data scatter. Thus, the interfacial test was discarded in favor of the fracture toughness test. Interfacial strength development was observed by measuring the refracture toughness of precracked compact tension specimens that were rehealed at a given temperature and contact time. The measured refracture toughness was correlated with temperature and contact time. Interfacial strength development in graphite-polysulfone unidirectional composites was measured using a double cantilever beam (DCB) interlaminar fracture toughness test. The critical strain energy release rate of refractured composite specimens was measured as a function of healing temperature and contact time.

  13. Interfacial gauge methods for incompressible fluid dynamics

    Science.gov (United States)

    Saye, Robert

    2016-01-01

    Designing numerical methods for incompressible fluid flow involving moving interfaces, for example, in the computational modeling of bubble dynamics, swimming organisms, or surface waves, presents challenges due to the coupling of interfacial forces with incompressibility constraints. A class of methods, denoted interfacial gauge methods, is introduced for computing solutions to the corresponding incompressible Navier-Stokes equations. These methods use a type of “gauge freedom” to reduce the numerical coupling between fluid velocity, pressure, and interface position, allowing high-order accurate numerical methods to be developed more easily. Making use of an implicit mesh discontinuous Galerkin framework, developed in tandem with this work, high-order results are demonstrated, including surface tension dynamics in which fluid velocity, pressure, and interface geometry are computed with fourth-order spatial accuracy in the maximum norm. Applications are demonstrated with two-phase fluid flow displaying fine-scaled capillary wave dynamics, rigid body fluid-structure interaction, and a fluid-jet free surface flow problem exhibiting vortex shedding induced by a type of Plateau-Rayleigh instability. The developed methods can be generalized to other types of interfacial flow and facilitate precise computation of complex fluid interface phenomena. PMID:27386567

  14. Interfacial gauge methods for incompressible fluid dynamics.

    Science.gov (United States)

    Saye, Robert

    2016-06-01

    Designing numerical methods for incompressible fluid flow involving moving interfaces, for example, in the computational modeling of bubble dynamics, swimming organisms, or surface waves, presents challenges due to the coupling of interfacial forces with incompressibility constraints. A class of methods, denoted interfacial gauge methods, is introduced for computing solutions to the corresponding incompressible Navier-Stokes equations. These methods use a type of "gauge freedom" to reduce the numerical coupling between fluid velocity, pressure, and interface position, allowing high-order accurate numerical methods to be developed more easily. Making use of an implicit mesh discontinuous Galerkin framework, developed in tandem with this work, high-order results are demonstrated, including surface tension dynamics in which fluid velocity, pressure, and interface geometry are computed with fourth-order spatial accuracy in the maximum norm. Applications are demonstrated with two-phase fluid flow displaying fine-scaled capillary wave dynamics, rigid body fluid-structure interaction, and a fluid-jet free surface flow problem exhibiting vortex shedding induced by a type of Plateau-Rayleigh instability. The developed methods can be generalized to other types of interfacial flow and facilitate precise computation of complex fluid interface phenomena.

  15. Macroscopic wettability based on an interfacial jump condition.

    Science.gov (United States)

    Yonemoto, Yukihiro; Kunugi, Tomoaki

    2010-05-01

    Young's equation, describing an interfacial equilibrium condition of a liquid droplet on a smooth solid surface, raises issues concerning the existence of a sine term which has not yet been resolved theoretically and continues to be discussed to the present day. From a thermodynamics viewpoint, the equilibrium condition arises by minimizing the total free energy of the system while intensive parameters are kept constant. In the derivation, variations in the virtual work in both horizontal and vertical directions of the droplet on the smooth solid are considered. From a hydrodynamics viewpoint, there is a momentum jump condition at the gas-liquid interface that is derived based on a mechanical balance. Using standard mathematical procedures such as Stokes' theorem and differential geometry, a test volume is considered across the interface between two continuous phases from which the jump condition is derived. In the present paper, Young's equation is revisited from the point of view of the momentum jump condition at the two-phase interface and a modified Young's equation is derived. The analytical solution derived from the modified Young's equation is then used to compare theory with experimental data. The line tension and contact angle for a lens droplet are also discussed on the basis of this model.

  16. Effect of culture at low oxygen tension on the expression of heat shock proteins in a panel of melanoma cell lines.

    Directory of Open Access Journals (Sweden)

    Christopher Shipp

    Full Text Available Tumours are commonly hypoxic and this can be associated with aggressive tumour type, metastasis and resistance to therapy. Heat shock proteins (hsps are induced in response to hypoxia, provide cancer cells with protection against tumour-associated stressors and chaperone oncoproteins that drive tumour proliferation. This study examined the effect of different oxygen concentrations on the expression of hsps in melanoma cell lines.Melanoma cell lines were cultured in 2% and 20% O(2. Expression of Hsp90, Hsp70, Hsp60, Hsp40 and Hsp32 proteins were determined by flow cytometry.Growth rates and viability were reduced in the majority of cell lines by culture in 2% O(2. Hsp expression was different in 2% compared to 20% O(2 and changes in Hsp90 expression correlated with cell line generation time (P<0.005 and viability (P<0.01. Greater total hsp expression correlated with improved viability in 2% but not 20% O(2 (P<0.05. Relative expression of the different hsps was consistent across cell lines and each correlated with the others (P = 0.0001 but not with Hsp32. Hsp expression was inversely correlated with cell line adhesion to laminin as well as collagen type IV and Breslow depth of the original primary tumour tissue (P<0.05, but not with Clark level or patient survival. All five hsps were identified on the cell surface.Culture in 2% O(2 variably altered hsp expression in a panel of melanoma cell lines. Hsp expression was associated with certain cell line characteristics and clinical parameters of the originating tumour.

  17. Effect of culture at low oxygen tension on the expression of heat shock proteins in a panel of melanoma cell lines.

    Science.gov (United States)

    Shipp, Christopher; Derhovanessian, Evelyna; Pawelec, Graham

    2012-01-01

    Tumours are commonly hypoxic and this can be associated with aggressive tumour type, metastasis and resistance to therapy. Heat shock proteins (hsps) are induced in response to hypoxia, provide cancer cells with protection against tumour-associated stressors and chaperone oncoproteins that drive tumour proliferation. This study examined the effect of different oxygen concentrations on the expression of hsps in melanoma cell lines. Melanoma cell lines were cultured in 2% and 20% O(2). Expression of Hsp90, Hsp70, Hsp60, Hsp40 and Hsp32 proteins were determined by flow cytometry. Growth rates and viability were reduced in the majority of cell lines by culture in 2% O(2). Hsp expression was different in 2% compared to 20% O(2) and changes in Hsp90 expression correlated with cell line generation time (P<0.005) and viability (P<0.01). Greater total hsp expression correlated with improved viability in 2% but not 20% O(2) (P<0.05). Relative expression of the different hsps was consistent across cell lines and each correlated with the others (P = 0.0001) but not with Hsp32. Hsp expression was inversely correlated with cell line adhesion to laminin as well as collagen type IV and Breslow depth of the original primary tumour tissue (P<0.05), but not with Clark level or patient survival. All five hsps were identified on the cell surface. Culture in 2% O(2) variably altered hsp expression in a panel of melanoma cell lines. Hsp expression was associated with certain cell line characteristics and clinical parameters of the originating tumour.

  18. Interfacial properties of chitosan/sodium dodecyl sulfate complexes

    Directory of Open Access Journals (Sweden)

    Milinković Jelena R.

    2017-01-01

    Full Text Available Contemporary formulations of cosmetic and pharmaceutical emulsions may be achieved by using combined polymer/surfactant system, which can form complexes with different structure and physicochemical properties. Such complexation can lead to additional stabilization of the emulsion products. For these reasons, the main goal of this study was to investigate the interfacial properties of chitosan/sodium dodecyl sulfate complexes. In order to understand the stabilization mechanism, the interface of the oil/water systems that contained mixtures of chitosan and sodium dodecyl sulfate, was studied by measuring the interfacial tension. Considering the fact that the properties of the oil phase has influence on the adsorption process, three different types of oil were investigated: medium-chain triglycerides (semi-synthetic oil, paraffin oil (mineral oil and natural oil obtained from the grape seed. The surface tension measurements at the oil/water interface, for chitosan water solutions, indicate a poor surface activity of this biopolymer. Addition of sodium dodecyl sulfate to chitosan solution causes a significant decrease in the interfacial tension for all investigated oils. The results of this study are important for understanding the influence of polymer-surfactant interactions on the properties of the solution and stability of dispersed systems. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III46010

  19. Skin tension related to tension reduction sutures.

    Science.gov (United States)

    Hwang, Kun; Kim, Han Joon; Kim, Kyung Yong; Han, Seung Ho; Hwang, Se Jin

    2015-01-01

    The aim of this study was to compare the skin tension of several fascial/subcutaneous tensile reduction sutures. Six upper limbs and 8 lower limbs of 4 fresh cadavers were used. At the deltoid area (10 cm below the palpable acromion) and lateral thigh (midpoint from the palpable greater trochanter to the lateral border of the patella), and within a 3 × 6-cm fusiform area of skin, subcutaneous tissue defects were created. At the midpoint of the defect, a no. 5 silk suture was passed through the dermis at a 5-mm margin of the defect, and the defect was approximated. The initial tension to approximate the margins was measured using a tensiometer.The tension needed to approximate skin without any tension reduction suture (S) was 6.5 ± 4.6 N (Newton). The tensions needed to approximate superficial fascia (SF) and deep fascia (DF) were 7.8 ± 3.4 N and 10.3 ± 5.1 N, respectively. The tension needed to approximate the skin after approximating the SF was 4.1 ± 3.4 N. The tension needed to approximate the skin after approximating the DF was 4.9 ± 4.0 N. The tension reduction effect of approximating the SF was 38.8 ± 16.4% (2.4 ± 1.5 N, P = 0.000 [ANOVA, Scheffé]). The tension reduction effect of approximating the DF was 25.2% ± 21.9% (1.5 ± 1.4 N, P = 0.001 [ANOVA, Scheffé]). The reason for this is thought to be that the SF is located closely to the skin unlike the DF. The results of this study might be a basis for tension reduction sutures.

  20. Reactor vessel stud tensioner

    International Nuclear Information System (INIS)

    Malandra, L.J.; Beer, R.W.; Salton, R.B.; Spiegelman, S.R.; Cognevich, M.L.

    1982-01-01

    A quick-acting stud tensioner, for facilitating the loosening or tightening of a stud nut on a reactor vessel stud, has gripper jaws which when the tensioner is lowered into engagement with the upper end of the stud are moved inwards to grip the upper end and which when the tensioner is lifted move outward to release the upper end. (author)

  1. LINES

    Directory of Open Access Journals (Sweden)

    Minas Bakalchev

    2015-10-01

    Full Text Available The perception of elements in a system often creates their interdependence, interconditionality, and suppression. The lines from a basic geometrical element have become the model of a reductive world based on isolation according to certain criteria such as function, structure, and social organization. Their traces are experienced in the contemporary world as fragments or ruins of a system of domination of an assumed hierarchical unity. How can one release oneself from such dependence or determinism? How can the lines become less “systematic” and forms more autonomous, and less reductive? How is a form released from modernistic determinism on the new controversial ground? How can these elements or forms of representation become forms of action in the present complex world? In this paper, the meaning of lines through the ideas of Le Corbusier, Leonidov, Picasso, and Hitchcock is presented. Spatial research was made through a series of examples arising from the projects of the architectural studio “Residential Transformations”, which was a backbone for mapping the possibilities ranging from playfulness to exactness, as tactics of transformation in the different contexts of the contemporary world.

  2. Pore-Scale Mechanisms of Colloid Interfacial Retention as Studied With Confocal Microscopy

    Science.gov (United States)

    Lazouskaya, V.; Jin, Y.

    2006-12-01

    Due to environmental concerns related to migration of colloids and colloid-facilitated transport of contaminants, interfacial retention of colloids has drawn significant scientific attention in past years. Nevertheless, there are still questions that remain debatable or unanswered concerning the mechanisms of interfacial retention of colloids. The experimental tools traditionally include column experiments, which provide macroscopic experimental data, but not always ensure their non-ambiguous explanation. Pore-scale visualization techniques provide additional information on the occurring processes and serve the purpose of explaining the phenomena observed at larger scales. The progress in the field of microscopy provides state-of-the-art techniques for visualization experiments where behavior of single colloids can be observed and therefore analysis of the particular retention mechanism can be performed. We applied confocal microscopy to investigate the two most arguable sites of colloidal retention: AWI (air-water interface) and contact line, which proved itself as a promising technique. The benefits of confocal microscopy include visualization of single colloids, flexible positioning of the sample and therefore direct observation of the point of interest. In addition, fast image acquisition allows imaging experiments to be conducted under dynamic conditions. The combination of confocal imaging with the specialized imaging software provides the added advantage of quantitative evaluations of the acquired images. In our experiments, confocal microscopy was applied to investigate the retention of colloids on AWI and contact line as affected by colloid and solution properties (e.g., surface tension and ionic strength). Particular attention was given to the behavior of colloids on the contact line both in static and dynamic regimes including the investigation of moving evaporative fronts. Additionally, the importance of hydrodynamic effect on the colloidal retention at

  3. Interfacial Friction and Adhesion of Polymer Brushes

    KAUST Repository

    Landherr, Lucas J. T.

    2011-08-02

    A bead-probe lateral force microscopy (LFM) technique is used to characterize the interfacial friction and adhesion properties of polymer brushes. Our measurements attempt to relate the physical structure and chemical characteristics of the brush to their properties as thin-film, tethered lubricants. Brushes are synthesized at several chain lengths and surface coverages from polymer chains of polydimethylsiloxane (PDMS), polystyrene (PS), and a poly(propylene glycol)-poly(ethylene glycol) block copolymer (PPG/PEG). At high surface coverage, PDMS brushes manifest friction coefficients (COFs) that are among the lowest recorded for a dry lubricant film (μ ≈ 0.0024) and close to 1 order of magnitude lower than the COF of a bare silicon surface. Brushes synthesized from higher molar mass chains exhibit higher friction forces than those created using lower molar mass polymers. Increased grafting density of chains in the brush significantly reduces the COF by creating a uniform surface of stretched chains with a decreased surface viscosity. Brushes with lower surface tension and interfacial shear stresses manifest the lowest COF. In particular, PDMS chains exhibit COFs lower than PS by a factor of 3.7 and lower than PPG/PEG by a factor of 4.7. A scaling analysis conducted on the surface coverage (δ) in relation to the fraction (ε) of the friction force developing from adhesion predicts a universal relation ε ∼ δ4/3, which is supported by our experimental data. © 2011 American Chemical Society.

  4. Interfacial Properties of a Hydrophobic Dye in the Tetrachloroethylene-Water-Glass Systems

    International Nuclear Information System (INIS)

    Tuck, D.M.

    1999-01-01

    Interfacial effects play an important role in governing multiphase fluid behavior in porous media. Strongly hydrophobic organic dyes, used in many experimental studies to facilitate visual observation of the phase distributions, have generally been implicitly assumed to have no influence on the interfacial properties of the various phases in porous media. Sudan IV is the most commonly used dye for non-aqueous phase liquids (NAPLs) in laboratory experiments. It has also been used in at least one field experiment. The effects of this dye on the tetrachloroethylene (PCE)-water-glass system were investigated to test the assumption that the dye does not effect the interfacial properties and therefore PCE mobility. The results indicate that the dye does indeed change the interfacial relationships.The effect of the dye on the interfacial relationships is a complex function of the dye concentration, the solid phase composition, and the dynamic rate of new interface formation. The dye caused a slight (<10 percent) increase in interfacial tension at low concentrations (<0.1 g/L) and high rates of new interface formation. The dye reduced interfacial tension between PCE and water at low rates of new interface formation for all dye concentrations tested (0.00508 to 5.08 g/L). At the highest dye concentration, the PCE-water interfacial tension was significantly reduced regardless of the rate of new interface formation. The apparent interfacial tension increase at low dye concentrations is suspected to be an artifact of a low measured IFT value for the undyed PCE caused by leaching of rubber o-rings by the PCE prior to testing in the final drop-volume configuration.In addition to reducing interfacial tension, the dye was found to significantly alter the wetting relationship between PCE and water on a glass surface at and above the range of reported dye concentrations cited in the literature (1.1 to 1.7 g/L). The wetting relationship was rendered neutral from a water-wet initial

  5. Interfacial Properties of a Hydrophobic Dye in the Tetrachloroethylene-Water-Glass Systems

    Energy Technology Data Exchange (ETDEWEB)

    Tuck, D.M.

    1999-02-23

    Interfacial effects play an important role in governing multiphase fluid behavior in porous media. Strongly hydrophobic organic dyes, used in many experimental studies to facilitate visual observation of the phase distributions, have generally been implicitly assumed to have no influence on the interfacial properties of the various phases in porous media. Sudan IV is the most commonly used dye for non-aqueous phase liquids (NAPLs) in laboratory experiments. It has also been used in at least one field experiment. The effects of this dye on the tetrachloroethylene (PCE)-water-glass system were investigated to test the assumption that the dye does not effect the interfacial properties and therefore PCE mobility. The results indicate that the dye does indeed change the interfacial relationships.The effect of the dye on the interfacial relationships is a complex function of the dye concentration, the solid phase composition, and the dynamic rate of new interface formation. The dye caused a slight (<10 percent) increase in interfacial tension at low concentrations (<0.1 g/L) and high rates of new interface formation. The dye reduced interfacial tension between PCE and water at low rates of new interface formation for all dye concentrations tested (0.00508 to 5.08 g/L). At the highest dye concentration, the PCE-water interfacial tension was significantly reduced regardless of the rate of new interface formation. The apparent interfacial tension increase at low dye concentrations is suspected to be an artifact of a low measured IFT value for the undyed PCE caused by leaching of rubber o-rings by the PCE prior to testing in the final drop-volume configuration.In addition to reducing interfacial tension, the dye was found to significantly alter the wetting relationship between PCE and water on a glass surface at and above the range of reported dye concentrations cited in the literature (1.1 to 1.7 g/L). The wetting relationship was rendered neutral from a water-wet initial

  6. Convection and surface tension profiles for aqueous droplet under microwave radiation

    Science.gov (United States)

    Kanazawa, Yushin; Asada, Masahiro; Asakuma, Yusuke; Honda, Itsuro; Phan, Chi; Parmar, Harisinh; Pareek, Vishnu; Evans, Geoffrey

    2014-08-01

    Application of microwave irradiation for chemical processes, such as emulsification and polymerization, has been reported [1,2]. Surfactant free emulsion can be produced with the help of microwave irradiation. Surface tension is an important property for the industrial process such as foaming/defoaming, wetting/dewetting and flotation. Similarly, the interfacial tension plays crucial role in separation and mixing process of two immiscible liquids, which are important unit operations of the fundamental chemical engineering. In practice, surface and interfacial tensions are often altered by introducing surfactants. In our previous research [3,4], specific property for surface tension of water droplet with salt under microwave radiation was found. For example, lower surface tension after the radiation was measured. The formation of nano-bubble will explain this behavior. Normally, the surface tension of aqueous solution increases with the salt concentration because cation and anion collect water molecule more strongly as a solvation. However, the exact mechanism of surface tension reduction by microwave radiation is not clear. We tried not only measurement of surface tension but also convection in the droplet during microwave radiation. This study investigates the influence of microwave on surface tension of aqueous solution. Moreover, relation between the concentration, temperature and droplet shape, which are related with surface tension.

  7. Diagnosis on line and off line of induction motors of low, medium and high voltage; Diagnostico en linea y fuera de linea de motores de induccion de baja, mediana y alta tension

    Energy Technology Data Exchange (ETDEWEB)

    Carvajal, Francisco Antonio; Ramirez, Jose Manuel; Arcos, Luis Fernando [Instituto de Investigaciones Electricas, Temixco, Morelos (Mexico)

    1999-07-01

    The induction motors of low, medium and high voltage are the electrical equipment of greatest application in industry. The importance which they have in the different productive processes does necessary to assure its operative continuity. The anticipated detection of a possible cause of fault allows to plan, with maintenance aims, the programmed removal of the motor. In this article are presented the results of the activities nowadays performed by Management of Electrical Equipment of the Instituto de Investigaciones Electricas (IIE) for the development and application of online diagnosis techniques for induction motors up to 13.8 kV. [Spanish] Los motores de induccion de baja, mediana y alta tension son los equipos eletricos de mayor aplicacion en la industria. La importancia que tienen en los diferentes procesos productivos hace necesario asegurar su continuidad operativa. La deteccion anticipada de una posible causa de falla permite planear, con fines de mantenimiento, la remocion programada del motor. En este articulo se presentan los resultados de las actividades que realiza actualmente la Gerencia de equipos Electricos del Instituto de investigaciones Electricas (IIE) para el desarrollo y la aplicacion de tecnicas de diagnostico en linea para motores de induccion de hasta 13.8 kV.

  8. Interfacial transport phenomena

    CERN Document Server

    Slattery, John C; Oh, Eun-Suok

    2007-01-01

    Revised and updated extensively from the previous editionDiscusses transport phenomena at common lines or three-phase lines of contactProvides a comprehensive summary about the extensions of continuum mechanics to the nanoscale.

  9. Liquid-vapor equilibrium and interfacial properties of square wells in two dimensions

    Science.gov (United States)

    Armas-Pérez, Julio C.; Quintana-H, Jacqueline; Chapela, Gustavo A.

    2013-01-01

    Liquid-vapor coexistence and interfacial properties of square wells in two dimensions are calculated. Orthobaric densities, vapor pressures, surface tensions, and interfacial thicknesses are reported. Results are presented for a series of potential widths λ* = 1.4, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, and 5, where λ* is given in units of the hard core diameter σ. Critical and triple points are explored. No critical point was found for λ* Armas-Pérez et al. [unpublished] as a hexatic phase transition. It is located at reduced temperatures T* = 0.47 and 0.35 for λ* = 1.4 and 1.5, respectively. Properties such as the surface tension, vapor pressure, and interfacial thickness do not present any discontinuity at these points. This amorphous solid branch does not follow the corresponding state principle, which is only applied to liquids and gases.

  10. Interfacial thermodynamics of water and six other liquid solvents.

    Science.gov (United States)

    Pascal, Tod A; Goddard, William A

    2014-06-05

    We examine the thermodynamics of the liquid-vapor interface by direct calculation of the surface entropy, enthalpy, and free energy from extensive molecular dynamics simulations using the two-phase thermodynamics (2PT) method. Results for water, acetonitrile, cyclohexane, dimethyl sulfoxide, hexanol, N-methyl acetamide, and toluene are presented. We validate our approach by predicting the interfacial surface tensions (IFT--excess surface free energy per unit area) in excellent agreement with the mechanical calculations using Kirkwood-Buff theory. Additionally, we evaluate the temperature dependence of the IFT of water as described by the TIP4P/2005, SPC/Ew, TIP3P, and mW classical water models. We find that the TIP4P/2005 and SPC/Ew water models do a reasonable job of describing the interfacial thermodynamics; however, the TIP3P and mW are quite poor. We find that the underprediction of the experimental IFT at 298 K by these water models results from understructured surface molecules whose binding energies are too weak. Finally, we performed depth profiles of the interfacial thermodynamics which revealed long tails that extend far into what would be considered bulk from standard Gibbs theory. In fact, we find a nonmonotonic interfacial free energy profile for water, a unique feature that could have important consequences for the absorption of ions and other small molecules.

  11. Tensions in Distributed Leadership

    Science.gov (United States)

    Ho, Jeanne; Ng, David

    2017-01-01

    Purpose: This article proposes the utility of using activity theory as an analytical lens to examine the theoretical construct of distributed leadership, specifically to illuminate tensions encountered by leaders and how they resolved these tensions. Research Method: The study adopted the naturalistic inquiry approach of a case study of an…

  12. Interfacial Instabilities in Evaporating Drops

    Science.gov (United States)

    Moffat, Ross; Sefiane, Khellil; Matar, Omar

    2007-11-01

    We study the effect of substrate thermal properties on the evaporation of sessile drops of various liquids. An infra-red imaging technique was used to record the interfacial temperature. This technique illustrates the non-uniformity in interfacial temperature distribution that characterises the evaporation process. Our results also demonstrate that the evaporation of methanol droplets is accompanied by the formation of wave-trains in the interfacial temperature field; similar patterns, however, were not observed in the case of water droplets. More complex patterns are observed for FC-72 refrigerant drops. The effect of substrate thermal conductivity on the structure of the complex pattern formation is also elucidated.

  13. Interfacial forces in aqueous media

    CERN Document Server

    van Oss, Carel J

    2006-01-01

    Thoroughly revised and reorganized, the second edition of Interfacial Forces in Aqueous Media examines the role of polar interfacial and noncovalent interactions among biological and nonbiological macromolecules as well as biopolymers, particles, surfaces, cells, and both polar and apolar polymers. The book encompasses Lifshitz-van der Waals and electrical double layer interactions, as well as Lewis acid-base interactions between colloidal entities in polar liquids such as water. New in this Edition: Four previously unpublished chapters comprising a new section on interfacial propertie

  14. Modeling interfacial area transport in multi-fluid systems

    Energy Technology Data Exchange (ETDEWEB)

    Yarbro, Stephen Lee [Univ. of California, Berkeley, CA (United States)

    1996-11-01

    Many typical chemical engineering operations are multi-fluid systems. They are carried out in distillation columns (vapor/liquid), liquid-liquid contactors (liquid/liquid) and other similar devices. An important parameter is interfacial area concentration, which determines the rate of interfluid heat, mass and momentum transfer and ultimately, the overall performance of the equipment. In many cases, the models for determining interfacial area concentration are empirical and can only describe the cases for which there is experimental data. In an effort to understand multiphase reactors and the mixing process better, a multi-fluid model has been developed as part of a research effort to calculate interfacial area transport in several different types of in-line static mixers. For this work, the ensemble-averaged property conservation equations have been derived for each fluid and for the mixture. These equations were then combined to derive a transport equation for the interfacial area concentration. The final, one-dimensional model was compared to interfacial area concentration data from two sizes of Kenics in-line mixer, two sizes of concurrent jet and a Tee mixer. In all cases, the calculated and experimental data compared well with the highest scatter being with the Tee mixer comparison.

  15. Lattice-Boltzmann Simulations of the Relationship Among Pressure, Saturation, and Interfacial Area in Porous Media

    Science.gov (United States)

    Schaap, M. G.; Porter, M. L.; Wildenschild, D.

    2008-12-01

    Capillary pressure plays an important role in multiphase flow through porous media. At the microscale, capillary pressure is defined by Laplace's law, which takes into account interfacial phenomena such as surface tension, interfacial curvature and the contact angle. However, at the macroscale, capillary pressure is taken to be a function of the wetting phase saturation alone and the pressures are measured separately in each phase, typically outside the porous medium. It has been hypothesized that in addition to saturation, capillary pressure should be a function of interfacial area per volume. In this study a comparison between interfacial areas obtained from microtomographic image data and lattice-Boltzmann simulations for drainage and imbibition processes is presented. It is shown that there is good agreement between the measured and simulated capillary pressure curves. In addition, there is agreement between the interfacial area estimates for drainage, however, interfacial area estimates for imbibition are higher in the simulations than in the experiments. Image analysis indicates that during imbibition there is substantially more flow via films in the lattice-Boltzmann simulations than in the experiments, which may explain the higher interfacial areas. Scanning curves for imbibition and drainage were also simulated and a surface was fit to the capillary pressure - saturation interfacial area data. The surface indicates that the additional dependence of capillary pressure on interfacial area may provide insights into the hysteretic nature of the capillary pressure- saturation relationship. Furthermore, this study suggests that interfacial area per volume is dependent upon the dominant flow mechanism (i.e. piston or finger) within the system, as well as, the connectedness of the wetting phase, thus providing valuable information that can not be obtained from the capillary pressure - saturation relationship alone.

  16. Strings with zero tension

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, R.; Barcelos-Neto, J.

    1988-05-01

    We describe bosonic strings by using a kind of Lagrangian compatible with the zero tension limit. The work is developed on an extended configuration space and the quantization is carried out with details.

  17. Parachute Cord Tension Sensor

    Data.gov (United States)

    National Aeronautics and Space Administration — To design and fabricate a light weight (few oz), very small (~2 inch length) parachute cord tension sensor demonstrator device.A major challenge for the CPAS (The...

  18. Optic nerve oxygen tension

    DEFF Research Database (Denmark)

    la Cour, M; Kiilgaard, Jens Folke; Eysteinsson, T

    2000-01-01

    To investigate the influence of acute changes in intraocular pressure on the oxygen tension in the vicinity of the optic nerve head under control conditions and after intravenous administration of 500 mg of the carbonic anhydrase inhibitor dorzolamide....

  19. Optic nerve oxygen tension

    DEFF Research Database (Denmark)

    la Cour, M; Kiilgaard, Jens Folke; Eysteinsson, T

    2000-01-01

    To investigate the influence of acute changes in intraocular pressure on the oxygen tension in the vicinity of the optic nerve head under control conditions and after intravenous administration of 500 mg of the carbonic anhydrase inhibitor dorzolamide.......To investigate the influence of acute changes in intraocular pressure on the oxygen tension in the vicinity of the optic nerve head under control conditions and after intravenous administration of 500 mg of the carbonic anhydrase inhibitor dorzolamide....

  20. The surface tension of pure liquids. Thermodynamic components and corresponding states

    NARCIS (Netherlands)

    Lyklema, J.

    1999-01-01

    From the temperature dependency of surface and interfacial tensions the surface excess energy and entropy per unit area can be obtained. The excess energy is a liquid-specific property; it varies over about three decades between liquid helium and molten metals. On the other hand, the excess entropy

  1. Scaling of interfacial jump conditions

    International Nuclear Information System (INIS)

    Quezada G, S.; Vazquez R, A.; Espinosa P, G.

    2015-09-01

    To model the behavior of a nuclear reactor accurately is needed to have balance models that take into account the different phenomena occurring in the reactor. These balances have to be coupled together through boundary conditions. The boundary conditions have been studied and different treatments have been given to the interface. In this paper is a brief description of some of the interfacial jump conditions that have been proposed in recent years. Also, the scaling of an interfacial jump condition is proposed, for coupling the different materials that are in contact within a nuclear reactor. (Author)

  2. Non-equilibrium surface tension of the vapour-liquid interface of active Lennard-Jones particles

    Science.gov (United States)

    Paliwal, Siddharth; Prymidis, Vasileios; Filion, Laura; Dijkstra, Marjolein

    2017-08-01

    We study a three-dimensional system of self-propelled Brownian particles interacting via the Lennard-Jones potential. Using Brownian dynamics simulations in an elongated simulation box, we investigate the steady states of vapour-liquid phase coexistence of active Lennard-Jones particles with planar interfaces. We measure the normal and tangential components of the pressure tensor along the direction perpendicular to the interface and verify mechanical equilibrium of the two coexisting phases. In addition, we determine the non-equilibrium interfacial tension by integrating the difference of the normal and tangential components of the pressure tensor and show that the surface tension as a function of strength of particle attractions is well fitted by simple power laws. Finally, we measure the interfacial stiffness using capillary wave theory and the equipartition theorem and find a simple linear relation between surface tension and interfacial stiffness with a proportionality constant characterized by an effective temperature.

  3. Interfacial and oil/water emulsions characterization of potato protein isolates.

    Science.gov (United States)

    Romero, Alberto; Beaumal, Valérie; David-Briand, Elisabeth; Cordobés, Felipe; Guerrero, Antonio; Anton, Marc

    2011-09-14

    Interfacial and emulsifying properties of potato protein isolate (PPI) have been studied to evaluate its potential application to stabilize oil/water emulsions at two pH values (2 and 8). The amount, type, and solubility of proteins and the size of aggregates have been determined in aqueous dispersion. Air-water and oil-water interfacial properties (adsorption, spreading, and viscoelastic properties) have been determined as a function of concentration and pH using soluble phases of PPI. The behavior of PPI stabilized oil/water emulsions has been then analyzed by droplet size distribution measurements and interfacial concentration. PPI exhibits low solubility over a wide range of pH values, with the presence of submicrometer aggregates. The pH value exerts a negligible effect on interfacial tension (oil-water) or surface pressure (air-water) but displays very important differences in viscoelastic properties of the interfacial films formed between oil and water. In this sense, pH 8 provides a major elastic response at oil-water interfaces as compared to pH 2. In relation with this result, a much higher ability to produce fine and stable emulsions is noticed at pH 8 as compared to pH 2. Consequently, there is an evident relationship between the rheological properties of the oil-water interfacial films and the macroscopic emulsion behavior.

  4. Dentin-cement Interfacial Interaction

    Science.gov (United States)

    Atmeh, A.R.; Chong, E.Z.; Richard, G.; Festy, F.; Watson, T.F.

    2012-01-01

    The interfacial properties of a new calcium-silicate-based coronal restorative material (Biodentine™) and a glass-ionomer cement (GIC) with dentin have been studied by confocal laser scanning microscopy (CLSM), scanning electron microscopy (SEM), micro-Raman spectroscopy, and two-photon auto-fluorescence and second-harmonic-generation (SHG) imaging. Results indicate the formation of tag-like structures alongside an interfacial layer called the “mineral infiltration zone”, where the alkaline caustic effect of the calcium silicate cement’s hydration products degrades the collagenous component of the interfacial dentin. This degradation leads to the formation of a porous structure which facilitates the permeation of high concentrations of Ca2+, OH-, and CO32- ions, leading to increased mineralization in this region. Comparison of the dentin-restorative interfaces shows that there is a dentin-mineral infiltration with the Biodentine, whereas polyacrylic and tartaric acids and their salts characterize the penetration of the GIC. A new type of interfacial interaction, “the mineral infiltration zone”, is suggested for these calcium-silicate-based cements. PMID:22436906

  5. Oxygen tension affects lubricin expression in chondrocytes.

    Science.gov (United States)

    Hatta, Taku; Kishimoto, Koshi N; Okuno, Hiroshi; Itoi, Eiji

    2014-10-01

    We assessed the effects of oxygen tension on lubricin expression in bovine chondrocytes and cartilage explants and a role for hypoxia-inducible transcription factor (HIF)-1α in regulating lubricin expression was investigated using a murine chondroprogenitor cell line, ATDC5, and bovine chondrocytes isolated from superficial and middle/deep zones of femoral cartilage. ATDC5 cells and bovine chondrocytes were cultured in micromass under different oxygen tensions (21%, 5%, and 1%). ATDC5 cells and middle/deep zone chondrocytes that initially had low lubricin expression levels were also cultured with or without transforming growth factor (TGF)-β1. Quantitative reverse transcription (RT)-PCR was used to determine lubricin and chondrogenic marker gene mRNA levels and immunohistochemistry was used to assess lubricin protein expression. Explant cartilage plugs cultured under different oxygen tensions were also subjected to immunohistological analysis for lubricin. HIF-1α gene silencing was achieved by electroporatic transfer into ATDC5 cells. A low oxygen tension reduced lubricin gene expression levels in bovine superficial chondrocytes, TGF-β1-treated middle/deep zone chondrocytes, and TGF-β1-treated ATDC5 cells. Lubricin expression in explant cartilage was also suppressed under hypoxia. HIF-1α gene silencing in ATDC5 cells attenuated the lubricin expression response to the oxygen tension. These results corroborate with previous studies that the oxygen tension regulates lubricin gene expression and suggest that HIF-1α plays an important role in this regulation. The normal distribution of lubricin in articular cartilage may be due to the hypoxic oxygen environment of cartilage as it is an avascular tissue. An oxygen tension gradient may be a key factor for engineering cartilage tissue with a layered morphology.

  6. The effects of viscosity, surface tension, and flow rate on gasoil-water flow pattern in microchannels

    Energy Technology Data Exchange (ETDEWEB)

    Boogar, Rahman Sadeghi; Gheshlaghi, Reza; Mahdavi, Mahmood Akhavan [Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of)

    2013-01-15

    A microchannel was fabricated with glass tubes to investigate the effect of viscosity, surface tension, and flow rate on the liquid-liquid two-phase flow regime. Water and gasoil were selected as aqueous and organic working fluids, respectively. The two fluids were injected into the microchannel and created either slug or parallel profile depending on the applied conditions. The range of Reynolds and capillary numbers was chosen in such a way that neither inertia nor interfacial tension forces were negligible. Xanthan gum was used to increase viscosity and Triton X-100 (TX-100) and Sodium Dodecyl Sulfate (SDS) were used to reduce the interfacial tension. The results demonstrated that higher value of viscosity and flow rate increased interfacial area, but slug flow regime remained unchanged. The two surfactants showed different effects on the flow regime and interfacial area. Addition of TX-100 did not change the slug flow but decreased the interfacial area. In contrast, addition of SDS increased interfacial area by decreasing the slug’s length in the low concentrations and by switching from slug to parallel regime at high concentrations.

  7. Optic nerve oxygen tension

    DEFF Research Database (Denmark)

    Kiilgaard, Jens Folke; Pedersen, D B; Eysteinsson, T

    2004-01-01

    The authors have previously reported that carbonic anhydrase inhibitors such as acetazolamide and dorzolamide raise optic nerve oxygen tension (ONPO(2)) in pigs. The purpose of the present study was to investigate whether timolol, which belongs to another group of glaucoma drugs called beta...

  8. Optic nerve oxygen tension

    DEFF Research Database (Denmark)

    Kiilgaard, Jens Folke; Pedersen, D B; Eysteinsson, T

    2004-01-01

    The authors have previously reported that carbonic anhydrase inhibitors such as acetazolamide and dorzolamide raise optic nerve oxygen tension (ONPO(2)) in pigs. The purpose of the present study was to investigate whether timolol, which belongs to another group of glaucoma drugs called beta block...

  9. Influence of Janus particle shape on their interfacial behavior at liquid-liquid interfaces.

    Science.gov (United States)

    Ruhland, Thomas M; Gröschel, André H; Ballard, Nicholas; Skelhon, Thomas S; Walther, Andreas; Müller, Axel H E; Bon, Stefan A F

    2013-02-05

    We investigate the self-assembly behavior of Janus particles with different geometries at a liquid-liquid interface. The Janus particles we focus on are characterized by a phase separation along their major axis into two hemicylinders of different wettability. We present a combination of experimental and simulation data together with detailed studies elucidating the mechanisms governing the adsorption process of Janus spheres, Janus cylinders, and Janus discs. Using the pendant drop technique, we monitor the assembly kinetics following changes in the interfacial tension of nanoparticle adsorption. According to the evolution of the interfacial tension and simulation data, we will specify the characteristics of early to late stages of the Janus particle adsorption and discuss the effect of Janus particle shape and geometry. The adsorption is characterized by three adsorption stages which are based on the different assembly kinetics and different adsorption mechanisms depending on the particle shape.

  10. Interfacial effects of surface-active agents under zinc pressure leach conditions

    Science.gov (United States)

    Owusu, George; Dreisinger, David B.; Peters, Ernest

    1995-02-01

    Liquid sulfur-zinc sulfate solution interfacial tensions and liquid sulfur-zinc sulfate solution-zinc sulfide (marmatite) contact angles were measured in the absence and presence of surface-active agents. Interfacial tensions measured varied between 54 ± 1 mN/m in the surfactant-free system and 20 ± 1 mN/m in the presence of a surfactant. The liquid sulfur-zinc sulfide mineral-zinc sulfate solution contact angle varies between 80 ± 5 deg, in the absence of any surfactant, and 148 ± 5 deg, depending on the surfactant used. The surface-active agents were used as dispersants for sulfur in bench-scale zinc pressure-leaching experiments. The observed extent of zinc extraction depends on the surfactant and varies from 40 to 96 pct.

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

    Science.gov (United States)

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

    2016-12-01

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

  12. Superstrings with zero tension

    Energy Technology Data Exchange (ETDEWEB)

    Barcelos-Neto, J.; Ruiz-Altaba, M. (European Organization for Nuclear Research, Geneva (Switzerland). Theory Div.)

    1989-09-14

    The superstring in the limit of vanishing tension is analyzed with the help of a phase space lagrangian. We show that our formulation is the supersymmetric extension of Schild's null string and that all the symmetries of the standard Green-Schwarz theory are maintained. The null superstring thus arises as a new theoretical laboratory, its complexity between the usual superstring and the massless superparticle. Its canonical quantization is carried through in detail. (orig.).

  13. Interfacial transport processes and rheology

    CERN Document Server

    Brenner, Howard

    1991-01-01

    This textbook is designed to provide the theory, methods of measurement, and principal applications of the expanding field of interfacial hydrodynamics. It is intended to serve the research needs of both academic and industrial scientists, including chemical or mechanical engineers, material and surface scientists, physical chemists, chemical and biophysicists, rheologists, physiochemical hydrodynamicists, and applied mathematicians (especially those with interests in viscous fluid mechanics and continuum mechanics).As a textbook it provides materials for a one- or two-semester graduate-level

  14. An arbitrary Lagrangian-Eulerian method for interfacial flows with insoluble surfactants

    Science.gov (United States)

    Yang, Xiaofeng

    Interfacial flows, fluid flows involving two or more fluids that do not mix, are common in many natural and industrial processes such as rain drop formation, crude oil recovery, polymer blending, fuel spray formation, and so on. Surfactants (surface active substances) play an important role in such processes because they significantly change the interfacial dynamics. In this thesis, an arbitrary Lagrangian-Eulerian (ALE) method has been developed to numerically simulate interfacial flows with insoluble surfactants. The interface is captured using a coupled level set and volume of fluid method. To evolve the surfactant concentration, the method directly tracks the surfactant mass and the interfacial area. The surfactant concentration, which determines the local surface tension through an equation of state, is then computed as surfactant mass per interfacial area. By directly tracking the surfactant mass, the method conserves the surfactant mass exactly. To accurately approximate the interfacial area, the fluid interface is reconstructed using piecewise parabolas. The evolution of the level set function, volume fraction, interfacial area, and the surfactant mass is performed using an ALE approach. The fluid flow is governed by Stokes equations, which are solved using a finite element method. The surface forces are included in the momentum equation using a continuum surface stress formulation. To efficiently resolve the complex interfacial dynamics, interfacial regions of high surface curvature, and near contact regions between two interacting interfaces, the grid near the interface is adaptively refined. The method is extendible to axisymmetric and 3D spaces, and can be coupled with other flow solvers, such as Navier-Stokes and viscoelastic flow solvers, as well. The method has been applied to study the effect of surfactants on drop deformation and breakup in an extensional flow. Drop deformation results are compared with available experimental and theoretical

  15. The analysis of interfacial waves

    International Nuclear Information System (INIS)

    Galimov, Azat Yu.; Drew, Donald A.; Lahey, Richard T.; Moraga, Francisco J.

    2005-01-01

    We present analytical results for stable stratified wavy two-phase flow and functional forms for the various interfacial force densities in a two-fluid model. In particular, we have derived analytically the components of the non-drag interfacial force density [Drew, D.A., Passman, S.L., 1998. Theory of Multicomponent Fluids. Springer-Verlag, New York; Nigmatulin, T.R., Drew, D.A., Lahey, R.T., Jr., 2000. An analysis of wavy annular flow. In: International Conference on Multiphase Systems, ICMS'2000, Ufa, Russia, June 15-17], Reynolds stress tensor, and the term, (p-bar cl i -p-bar cl )-bar α cl , where p-bar cl i is interfacial average pressure, p-bar cl the average pressure, and α cl is the volume fraction of the continuous liquid phase. These functional forms should be useful for assessing two-fluid closure relations and Computational Multiphase Fluid Dynamics (CMFD) numerical models for stratified wavy flows. Moreover, it appears that this approach can be generalized to other flow regimes (e.g., annular flows)

  16. Wetting process and interfacial characteristic of Sn-3.0Ag-0.5Cu on different substrates at temperatures ranging from 503 K to 673 K

    Science.gov (United States)

    Zang, Likun; Yuan, Zhangfu; Xu, Hongyan; Xu, Bingsheng

    2011-03-01

    Wetting process and interfacial characteristic of Sn-3.0Ag-0.5Cu have been investigated at temperatures ranging from 503 K to 673 K on Cu, Ni, stainless steel and quartz, respectively. The reactive wetting behavior of Sn-3.0Ag-0.5Cu melt alloy on Cu and Ni substrates were investigated. Contact angles decrease as exponential decay and equilibrium contact angles decrease between the solder and Cu, Ni substrates monotonously with the temperature increasing. The configuration of the triple line of Sn-3.0Ag-0.5Cu/Cu is discussed by the description of equilibrium. The calculated results based on experimental values of tension balances along each of the three interfaces at this final state show good agreement with theoretical analysis. Intermetallics of the Sn-3.0Ag-0.5Cu/Ni interface are identified as (Cu, Ni) 6Sn 5 adjacent to the solder and Ni 3Sn 4 adjacent to the Ni substrate, respectively. The contact angles between Sn-3.0Ag-0.5Cu and quartz, stainless steel substrates were measured to be greater than 90°, which means non-wetting, in the temperature range from 503 K to 673 K. Liquid-solid interfacial energy between the solder and different substrates are obtained based on the surface tension of molten solder and equilibrium contact angles at different temperatures. These results are of practical interest for composite lead-free solders preparations and joining of Sn-3.0Ag-0.5Cu to various substrates.

  17. Tension-type headache

    DEFF Research Database (Denmark)

    Bendtsen, Lars; Jensen, Rigmor; Bendtsen, Lars

    2009-01-01

    The substantial societal and individual burdens associated with tension-type headache (TTH) constitute a previously overlooked major public health issue. TTH is prevalent, affecting up to 78% of the general population, and 3% suffer from chronic TTH. Pericranial myofascial nociception probably...... is important for the pathophysiology of episodic TTH, whereas sensitization of central nociceptive pathways seems responsible for the conversion of episodic to chronic TTH. Headache-related disability usually can be reduced by identification of trigger factors combined with nonpharmacologic and pharmacologic...

  18. Interfacial reactions between titanium and borate glass

    Energy Technology Data Exchange (ETDEWEB)

    Brow, R.K. [Sandia National Labs., Albuquerque, NM (United States); Saha, S.K.; Goldstein, J.I. [Lehigh Univ., Bethlehem, PA (United States). Dept. of Materials Science

    1992-12-31

    Interfacial reactions between melts of several borate glasses and titanium have been investigated by analytical scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS). A thin titanium boride interfacial layer is detected by XPS after short (30 minutes) thermal treatments. ASEM analyses after longer thermal treatments (8--120 hours) reveal boron-rich interfacial layers and boride precipitates in the Ti side of the interface.

  19. Universal deformation of soft substrates near a contact line and the direct measurement of solid surface stresses.

    Science.gov (United States)

    Style, Robert W; Boltyanskiy, Rostislav; Che, Yonglu; Wettlaufer, J S; Wilen, Larry A; Dufresne, Eric R

    2013-02-08

    Droplets deform soft substrates near their contact lines. Using confocal microscopy, we measure the deformation of silicone gel substrates due to glycerol and fluorinated-oil droplets for a range of droplet radii and substrate thicknesses. For all droplets, the substrate deformation takes a universal shape close to the contact line that depends on liquid composition, but is independent of droplet size and substrate thickness. This shape is determined by a balance of interfacial tensions at the contact line and provides a novel method for direct determination of the surface stresses of soft substrates. Moreover, we measure the change in contact angle with droplet radius and show that Young's law fails for small droplets when their radii approach an elastocapillary length scale. For larger droplets the macroscopic contact angle is constant, consistent with Young's law.

  20. Capillary meniscus dynamometry - Method for determining the surface tension of drops and bubbles with isotropic and anisotropic surface stress distributions

    NARCIS (Netherlands)

    Danov, K.D.; Stanimirova, R.D.; Kralchevsky, P.A.; Marinova, K.G.; Alexandrov, N.A.; Stoyanov, S.D.; Blijdenstein, T.B.J.; Pelan, E.G.

    2015-01-01

    The stresses acting in interfacial adsorption layers with surface shear elasticity are, in general, anisotropic and non-uniform. If a pendant drop or buoyant bubble is covered with such elastic layer, the components of surface tension acting along the "meridians" and "parallels", σs

  1. Apparent Interfacial Fracture Toughness of Resin/Ceramic Systems

    Science.gov (United States)

    Della Bona, A.; Anusavice, K.J.; Mecholsky, J.J.

    2008-01-01

    We suggest that the apparent interfacial fracture toughness (KA) may be estimated by fracture mechanics and fractography. This study tested the hypothesis that the KA of the adhesion zone of resin/ceramic systems is affected by the ceramic microstructure. Lithia disilicate-based (Empress2-E2) and leucite-based (Empress-E1) ceramics were surface-treated with hydrofluoric acid (HF) and/or silane (S), followed by an adhesive resin. Microtensile test specimens (n = 30; area of 1 ± 0.01 mm2) were indented (9.8 N) at the interface and loaded to failure in tension. We used tensile strength (σ) and the critical crack size (c) to calculate KA (KA = Yσc1/2) (Y = 1.65). ANOVA and Weibull analyses were used for statistical analyses. Mean KA (MPa•m1/2) values were: (E1HF) 0.26 ± 0.06; (E1S) 0.23 ± 0.06; (E1HFS) 0.30 ± 0.06; (E2HF) 0.31 ± 0.06; (E2S) 0.13 ± 0.05; and (E2HFS) 0.41 ± 0.07. All fractures originated from indentation sites. Estimation of interfacial toughness was feasible by fracture mechanics and fractography. The KA for the systems tested was affected by the ceramic microstructure and surface treatment. PMID:17062746

  2. General definition of gravitational tension

    International Nuclear Information System (INIS)

    Harmark, T.; Obers, N.A.

    2004-01-01

    In this note we give a general definition of the gravitational tension in a given asymptotically translationally-invariant spatial direction of a space-time. The tension is defined via the extrinsic curvature in analogy with the Hawking-Horowitz definition of energy. We show the consistency with the ADM tension formulas for asymptotically-flat space-times, in particular for Kaluza-Klein black hole solutions. Moreover, we apply the general tension formula to near-extremal branes, constituting a check for non-asymptotically flat space-times. (author)

  3. Interfacial heat transfer - State of the art

    International Nuclear Information System (INIS)

    Yadigaroglu, G.

    1987-01-01

    Interfacial heat exchanges control the interfacial mass exchange rate, depend on the interfacial area, and are tied to the prediction of thermal nonequilibrium. The nature of the problem usually requires the formulation of mechanistic laws and precludes the general use of universal correlations. This is partly due to the fact that the length scale controlling the interfacial exchanges varies widely from one situation to another and has a strong influence on the exchange coefficients. Within the framework of the ''two-fluid models'', the exchanges occurring at the interfaces are explicitly taken into consideration by the jump condition linking the volumetric mass exchange (evaporation) rate between the phases, to the interfacial energy transfer rates

  4. Surface Tension of Supercooled Water Determined by Using a Counterpressure Capillary Rise Method

    Czech Academy of Sciences Publication Activity Database

    Vinš, Václav; Fransen, M. A. L. J.; Hykl, Jiří; Hrubý, Jan

    2015-01-01

    Roč. 119, č. 17 (2015), s. 5567-5575 ISSN 1520-6106 R&D Projects: GA MŠk LG13056; GA ČR GJ15-07129Y Institutional support: RVO:61388998 Keywords : capillary tube * interfacial tension * metastable liquid * supercooled liquid Subject RIV: BJ - Thermodynamics Impact factor: 3.187, year: 2015 http://pubs.acs.org/doi/abs/10.1021/acs.jpcb.5b00545

  5. Tear Lipids Interfacial Rheology: Effect of Lysozyme and Lens Care Solutions

    Science.gov (United States)

    Svitova, Tatyana F.; Lin, Meng C.

    2014-01-01

    Purpose To evaluate the interfacial properties of ex vivo tear lipid multilayers with controlled and varying thickness. The influence of lysozyme and surfactant-containing multi-purpose lens care solutions (MPS) on interfacial rheology of lipids and mixed lipid-protein films were studied. Methods Lipids were extracted from lotrafilcon A lenses worn continuously for 1 month. Interfacial properties of the lipids without and with lysozyme in the aqueous phase were examined using tensiometry and step-strain relaxation. Lipid-lysozyme multilayers were exposed to either diluted Optifree Express (OFX) or Optifree Replenish (OFR) for 30 min, and then MPS was displaced from the bulk phase. Surface tension and rheological parameters before and after MPS exposure were measured and compared. Results Thick lipid films exerted high surface pressure at the air-aqueous interface, 50 ± 2 mN/m, with little inter- and intra-subject variability. The rheological storage modulus (E∞; 25.3 ± 2 mN/m) and relaxation time (τ; 87 ± 25 s) were similar among subjects. Neither lysozyme nor MPS changed the surface tension of the lipid multilayers. Lysozyme adsorbed irreversibly onto multilayers without changing E∞, but increased τ 2.5 times. Exposure of mixed multilayers to OFX reduced E∞ to less than a half of its original value (13 ± 4.5 mN/m; p rheology of the ex vivo lipids. OFX and OFR changed rheological properties of the mixed films to different extents. PMID:19901859

  6. MUSCLE TENSION DYSPHONIA

    Directory of Open Access Journals (Sweden)

    Irena Hočevar Boltežar

    2004-07-01

    Full Text Available Background. Muscle tension dysphonia (MTD is the cause of hoarseness in almost one half of the patients with voice disorders. The otorhinolaryngologic examination discovers no evident organic lesions in the larynx at least in the beginning of the voice problems. The reason for the hoarse voice is a disordered and maladjusted activity of the muscles taking part in phonation and/or articulation. In some patients, the irregular function of the larynx results in mucosal lesions on vocal folds. The factors participating in the development of MTD, directly or indirectly influence the quality of laryngeal mucosa, the activity of the phonatory muscles and/or increase of the vocal load. In the diagnostics and treatment of the MTD a phoniatrician, a speech and language therapist and a psychologist closely cooperate with the patient who must take an active role. The treatment is a long-lasting one but resulted in a high percentage of clinical success.Conclusions. Most likely, MTD is not a special disease but only a reflection of any disorder in the complicated system of regulation and realization of phonation. The prognosis of treatment is good when all unfavourable factors participating in development of MTD are eliminated and a proper professional voice- and psychotherapy started.

  7. Rheological and interfacial properties at the equilibrium of almond gum tree exudate (Prunus dulcis) in comparison with gum arabic.

    Science.gov (United States)

    Mahfoudhi, Nesrine; Sessa, Mariarenata; Ferrari, Giovanna; Hamdi, Salem; Donsi, Francesco

    2016-06-01

    Almond gum contains an arabinogalactan-type polysaccharide, which plays an important role in defining its interfacial and rheological properties. In this study, rheological and interfacial properties of almond gum and gum arabic aqueous dispersions were comparatively investigated. The interfacial tension of almond gum and gum arabic aqueous dispersions was measured using the pendant drop method in hexadecane. The asymptotic interfacial tension values for almond gum were significantly lower than the corresponding values measured for gum arabic, especially at high concentration. Rheological properties were characterized by steady and oscillatory tests using a coaxial geometry. Almond gum flow curves exhibited a shear thinning non-Newtonian behavior with a tendency to a Newtonian plateau at low shear rate, while gum arabic flow curves exhibited such behavior only at high shear rate. The influence of temperature (5-50  ℃) on the flow curves was studied at 4% (m/m) gum concentration and the Newtonian viscosities at infinite and at zero shear rate, for gum arabic and almond gum, respectively, were accurately fitted by an Arrhenius-type equation. The dynamic properties of the two gum dispersions were also studied. Both gum dispersions exhibited viscoelastic properties, with the viscous component being predominant in a wider range of concentrations for almond gum, while for gum arabic the elastic component being higher than the elastic one especially at higher concentrations.The rheological and interfacial tension properties of almond gum suggest that it may represent a possible substitute of gum arabic in different food applications. © The Author(s) 2015.

  8. Interfacial Transport Phenomena (Second edition)

    NARCIS (Netherlands)

    Slattery, J.C.; Sagis, L.M.C.; Oh, E.S.

    2007-01-01

    Gives a presentation of transport phenomena or continuum mechanics focused on momentum, energy, and mass transfer at interfaces. This work includes a discussion of transport phenomena at common lines or three-phase lines of contact, and a theory for the extension of continuum mechanics to the

  9. Interfacial behaviour between oil/water systems using ionic surfactants from regional vegetable industry and animal pet

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Francisco Klebson G.; Alves, Juan V.A.; Dantas, Tereza N. Castro; Dutra Junior, Tarcilio V.; Barros Neto, Eduardo L. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2008-07-01

    Interfacial tension (IFT) is one of the most important physical properties in the study of fluid-fluid interfaces. In this research the surfactants - saponified coconut oil, saponified castor oil, saponified soybean oil, saponified sunflower oil and basis soap - were synthesized in laboratory, using carboxylic acids from regional industry and animal fat (bovine fat). This study focuses on the search of a high-efficient, low-cost, and safe for the environment flooding system to be applied in enhanced oil recovery. The principal aim of this work is the obtaining of interfacial tensions between oil/water systems, using the developed ionic surfactants. Results showed that the studied surfactants are able to reduce the IFT between oil and brine. The surfactant that was more effective in reducing the IFT value was the one from animal fat. The composition, as well as the kind of the bond, as saturated or unsaturated, of the surfactants has influence in the IFT value. The ionic surfactants from regional industry and animal fat besides presenting low cost propitiate very low interfacial tensions between oil and brine, favoring the interactions with residual oil and thus increasing oil recovery. (author)

  10. Physicochemically functional ultrathin films by interfacial polymerization

    Science.gov (United States)

    Lonsdale, Harold K.; Babcock, Walter C.; Friensen, Dwayne T.; Smith, Kelly L.; Johnson, Bruce M.; Wamser, Carl C.

    1990-01-01

    Interfacially-polymerized ultrathin films containing physicochemically functional groups are disclosed, both with and without supports. Various applications are disclsoed, including membrane electrodes, selective membranes and sorbents, biocompatible materials, targeted drug delivery, and narrow band optical absorbers.

  11. Note: A thermally stable tension meter for atmospheric soundings using kites.

    Science.gov (United States)

    Walesby, K T; Harrison, R G

    2010-07-01

    Kites offer considerable potential as wind speed sensors--a role distinct from their traditional use as instrument-carrying platforms. In the sensor role, wind speed is measured by kite-line tension. A kite tether line tension meter is described here, using strain gauges mounted on an aluminum ring in a Wheatstone bridge electronic circuit. It exhibits a linear response to tension (19.5 mV N(-1)) with good thermal stability (mean drift of -0.18 N degrees C(-1) over 5-45 degrees C temperature range) and a rapid time response (0.2 s or better). Field comparisons of tether line tension for a Rokkaku kite with a fixed tower sonic anemometer show an approximately linear tension-wind speed relationship over the range 1-6 ms(-1).

  12. Interfacial structures - Thermodynamical and experimental studies of the interfacial mass transfer

    International Nuclear Information System (INIS)

    Morel, Jean-Emile

    1972-01-01

    In the first section, we put forward hypotheses concerning the structure of the interfacial regions between two immiscible liquid phases. It appears that the longitudinal structure is comparable with that of a crystallized solid and that the transversal structure is nearest of that of a liquid. In the second section, we present a thermodynamical treatment of the irreversible phenomena in the interfacial region. The equation of evolution of a system consisting of two immiscible liquid phases are deduced. The third part allows an experimental verification of the theoretical relations. We also make clear, in certain cases, the appearance of a great 'interfacial resistance' which slows down the interfacial mass transfer. (author) [fr

  13. Modeling interfacial fracture in Sierra.

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Arthur A.; Ohashi, Yuki; Lu, Wei-Yang; Nelson, Stacy A. C.; Foulk, James W.,; Reedy, Earl David,; Austin, Kevin N.; Margolis, Stephen B.

    2013-09-01

    This report summarizes computational efforts to model interfacial fracture using cohesive zone models in the SIERRA/SolidMechanics (SIERRA/SM) finite element code. Cohesive surface elements were used to model crack initiation and propagation along predefined paths. Mesh convergence was observed with SIERRA/SM for numerous geometries. As the funding for this project came from the Advanced Simulation and Computing Verification and Validation (ASC V&V) focus area, considerable effort was spent performing verification and validation. Code verification was performed to compare code predictions to analytical solutions for simple three-element simulations as well as a higher-fidelity simulation of a double-cantilever beam. Parameter identification was conducted with Dakota using experimental results on asymmetric double-cantilever beam (ADCB) and end-notched-flexure (ENF) experiments conducted under Campaign-6 funding. Discretization convergence studies were also performed with respect to mesh size and time step and an optimization study was completed for mode II delamination using the ENF geometry. Throughout this verification process, numerous SIERRA/SM bugs were found and reported, all of which have been fixed, leading to over a 10-fold increase in convergence rates. Finally, mixed-mode flexure experiments were performed for validation. One of the unexplained issues encountered was material property variability for ostensibly the same composite material. Since the variability is not fully understood, it is difficult to accurately assess uncertainty when performing predictions.

  14. Mitochondrial Respiration and Oxygen Tension.

    Science.gov (United States)

    Shaw, Daniel S; Meitha, Karlia; Considine, Michael J; Foyer, Christine H

    2017-01-01

    Measurements of respiration and oxygen tension in plant organs allow a precise understanding of mitochondrial capacity and function within the context of cellular oxygen metabolism. Here we describe methods that can be routinely used for the isolation of intact mitochondria, and the determination of respiratory electron transport, together with techniques for in vivo determination of oxygen tension and measurement of respiration by both CO 2 production and O 2 consumption that enables calculation of the respiratory quotient [CO 2 ]/[O 2 ].

  15. Effect of Atmospheric Ions on Interfacial Water

    Directory of Open Access Journals (Sweden)

    Chien-Chang Kurt Kung

    2014-11-01

    Full Text Available The effect of atmospheric positivity on the electrical properties of interfacial water was explored. Interfacial, or exclusion zone (EZ water was created in the standard way, next to a sheet of Nafion placed horizontally at the bottom of a water-filled chamber. Positive atmospheric ions were created from a high voltage source placed above the chamber. Electrical potential distribution in the interfacial water was measured using microelectrodes. We found that beyond a threshold, the positive ions diminished the magnitude of the negative electrical potential in the interfacial water, sometimes even turning it to positive. Additionally, positive ions produced by an air conditioner were observed to generate similar effects; i.e., the electrical potential shifted in the positive direction but returned to negative when the air conditioner stopped blowing. Sometimes, the effect of the positive ions from the air conditioner was strong enough to destroy the structure of interfacial water by turning the potential decidedly positive. Thus, positive air ions can compromise interfacial water negativity and may explain the known negative impact of positive ions on health.

  16. Diffusion coefficients-surface and interfacial tensions - Particular study of some lauryl compounds

    International Nuclear Information System (INIS)

    Morel, Jean-Emile

    1969-01-01

    Two important results of the double lipophilic and hydrophilic character of some heavy organic compounds with a polar group at the end of the chain, were studied: - In a first part, molecular diffusion coefficients were measured in order to prove the micellar aggregation of tri-laurylammonium nitrate in some organic solutions; - In a second part, the tensioactivity of some lauryl compounds (lauric acid, lauric alcohol, mono-laurylamine, etc.), was studied. (author) [fr

  17. Prediction of Interfacial Tensions of Reservoir Crude Oil and Gas Condensate Systems

    DEFF Research Database (Denmark)

    Zuo, You-Xiang; Stenby, Erling Halfdan

    1998-01-01

    . Correlations of the model parameters were presented for pseudocomponents. The characterization procedures of Pedersen et al. and the SRK equation of state (EOS) were used to calculate vapor-liquid equilibria (VLE). To the exclusion of the near-critical region, the IFT’s calculated by all the models except...... the CS correlation were in good agreement with the measured IFT data for several crude oil and CO2/oil systems. The SLGT model and the parachor model perform better than the LGT model and the CS correlation. For N 2 volatile oil systems, the performance of the LGT model is better than that of the SLGT...... model and the parachor model. For gas condensate systems, the predictions by use of the SLGT model are in good agreement with the measured IFT data. In the near-critical region, a correlation was proposed for estimations of IFT’s for CO2/oil systems, and satisfactory correlated results were obtained....

  18. Effects of non-uniform interfacial tension in small Reynolds number ...

    Indian Academy of Sciences (India)

    We follow the well-established method of solution as devised by Proudman and Pear- son [12] and Taylor and Acrivos [1]. The calculations are lengthy. We shall therefore only present the results and verify that they agree with the established solutions in the appropriate limits. 3. Perturbation solution. The problem is a ...

  19. Profiling and study of interfacial tension laden with crude lipid extract ...

    African Journals Online (AJOL)

    Crude lipid extract plant based namely SPLIP and PULIP are being introduced in this research as a potential surfactant with phospholipid and glycolipid components which playing an important role at the oil/water interface. Since the interaction between the components give a significant impact on the interfaces, the aim of ...

  20. Effects of non-uniform interfacial tension in small Reynolds number ...

    Indian Academy of Sciences (India)

    Centre for Differential Equations, Continuum Mechanics and Applications, School of Computational and Applied Mathematics, University of the Witwatersrand, Johannesburg, Private Bag 3, Wits 2050, South Africa; Department of Mathematical Sciences, University of South Africa, P.O. Box 392, Pretoria 0003, South Africa ...

  1. Use of Surfactants to Decrease Air-Water Interfacial Tension During Sparging

    Science.gov (United States)

    Air sparging is a remediation procedure of injecting air into polluted ground water. The primary intention of air sparging is to promote biodegradation of volatile organic compounds (VOCs) in the groundwater passing through the treatment sector. Sparging treatment efficiency dep...

  2. Use of Surfactants to Decrease Air-Water Interfacial Tension During Sparging (OKC, OK)

    Science.gov (United States)

    Air sparging is a remediation procedure of injecting air into polluted ground water. The primary intention of air sparging is to promote biodegradation of volatile organic compounds (VOCs) in the groundwater passing through the treatment sector. Sparging treatment efficiency dep...

  3. Simulation of Flow Behavior of Gas Condensate at Low Interfacial Tension

    DEFF Research Database (Denmark)

    Wang, Peng; Stenby, Erling Halfdan; Pope, Gary A.

    1996-01-01

    ) in the measurement, more attention is paid to the influence of IFT on gas/oil flow behavior. Two different types of model are used to compute the relative permeability. Model I is a Corey-type model combined with the capillary number concept. Model II is a modified form of the model proposed by Coats.The simulation...... results indicate that the effect of low IFT on relative permeability can be reasonably described by the two models selected, although the producing gas-oil ratio (GOR) obtained using Model I deviates somewhat from the experimental values in later depletion stages. The condensed liquid can be a mobile...... phase at very low liquid saturation, since the IFT is so low that the capillary force can be neglected. The liquid flows through the porous medium under the control of gra vity in this case....

  4. Interfacial phenomena and microscale transport processes in evaporating ultrathin menisci

    Science.gov (United States)

    Panchamgam, Sashidhar S.

    The study of interfacial phenomena in the three-phase contact line region, where a liquid-vapor interface intersects a solid surface, is of importance to many equilibrium and non-equilibrium processes. However, lack of experimental data on microscale transport processes controlled by interfacial phenomena has restricted progress. This thesis includes a high resolution image analyzing technique, based on reflectivity measurements, that accurately measures the thickness, contact angle and curvature profiles of ultrathin films, drops and curved menisci. In particular, the technique was used to emphasize measurements for thicknesses, delta contact line region. Experiments included flow instabilities in HFE-7000 meniscus on quartz (System S1), the spreading of a pentane (System S2 and S3), octane (System S4) and binary mixture menisci (System S5) during evaporation. The main objectives of the work are to present a new experimental technique, new observations, new data, and the use of a simple control volume, continuum and Kelvin-Clapeyron models to discuss the results. In addition, the interplay and importance of the microscopic fundamental forces, i.e., van der Waals forces, capillary forces and Marangoni stresses, during evaporation of the wetting fluids on the quartz surface is emphasized.

  5. Crystallographic Analysis of Fatigue Crack Initiation Behavior in Coarse-Grained Magnesium Alloy Under Tension-Tension Loading Cycles

    Science.gov (United States)

    Tamada, Kazuhiro; Kakiuchi, Toshifumi; Uematsu, Yoshihiko

    2017-07-01

    Plane bending fatigue tests are conducted to investigate fatigue crack initiation mechanisms in coarse-grained magnesium alloy, AZ31, under the stress ratios R = -1 and 0.1. The initial crystallographic structures are analyzed by an electron backscatter diffraction method. The slip or twin operation during fatigue tests is identified from the line angle analyses based on Euler angles of the grains. Under the stress ratio R = -1, relatively thick tension twin bands are formed in coarse grains. Subsequently, compression twin or secondary pyramidal slip operates within the tension twin band, resulting in the fatigue crack initiation. On the other hand, under R = 0.1 with tension-tension loading cycles, twin bands are formed on the specimen surface, but the angles of those bands do not correspond to tension twins. Misorientation analyses of c-axes in the matrix grain and twin band reveal that double twins are activated. Under R = 0.1, fatigue crack initiates along the double twin boundaries. The different manners of fatigue crack initiation at R = -1 and 0.1 are related to the asymmetricity of twining under tension and compression loadings. The fatigue strengths under different stress ratios cannot be estimated by the modified Goodman diagram due to the effect of stress ratio on crack initiation mechanisms.

  6. Interfacial functionalization and engineering of nanoparticles

    Science.gov (United States)

    Song, Yang

    also of the metal elements in the nanoparticle cores, in contrast to the bulk-exchange counterparts where these distributions were homogeneous within the nanoparticles, as manifested in contact angle, UV--vis, XPS, and TEM measurements. More interestingly, the electrocatalytic performance of the Janus nanoparticles was markedly better than the bulk-exchange ones, suggesting that the segregated distribution of the polar ligands from the apolar ones might further facilitate charge transfer from Ag to Au in the nanoparticle cores, leading to additional improvement of the adsorption and reduction of oxygen. This interfacial protocol was then adopted to prepare trimetallic Ag AuPt Neapolitan nanoparticles by two sequential galvanic exchange reactions of 1-hexanethiolate-capped silver nanoparticles with gold(I)-thiomalic acid and platinum(II)-hexanethiolate complexes. As both reactions were confined to an interface, the Au and Pt elements were situated on two opposite poles of the original Ag nanoparticles, which was clearly manifested in elemental mapping of the nanoparticles, and consistent with the damping and red-shift of the nanoparticle surface plasmon resonance. As nanoscale analogs to conventional amphiphilic molecules, the resulting Janus nanoparticles were found to form oil-in-water micelle-like or water-in-oil reverse micelle-like superparticulate structures depending on the solvent media. These unique characteristics were exploited for the effective transfer of diverse guest nanoparticles between organic and water phase. The transfer of hydrophobic nanoparticles from organic to water media or water-soluble nanoparticles to the organic phase was evidenced by TEM, DLS, UV-Vis, and PL measurements. In particular, line scans based on EDS analysis showed that the vesicle-like structures consisted of multiple layers of the Janus nanoparticles, which encapsulated the guest nanoparticles in the cores. The results highlight the unique effectiveness of using Janus

  7. Interfacial phase-change memory.

    Science.gov (United States)

    Simpson, R E; Fons, P; Kolobov, A V; Fukaya, T; Krbal, M; Yagi, T; Tominaga, J

    2011-07-03

    Phase-change memory technology relies on the electrical and optical properties of certain materials changing substantially when the atomic structure of the material is altered by heating or some other excitation process. For example, switching the composite Ge(2)Sb(2)Te(5) (GST) alloy from its covalently bonded amorphous phase to its resonantly bonded metastable cubic crystalline phase decreases the resistivity by three orders of magnitude, and also increases reflectivity across the visible spectrum. Moreover, phase-change memory based on GST is scalable, and is therefore a candidate to replace Flash memory for non-volatile data storage applications. The energy needed to switch between the two phases depends on the intrinsic properties of the phase-change material and the device architecture; this energy is usually supplied by laser or electrical pulses. The switching energy for GST can be reduced by limiting the movement of the atoms to a single dimension, thus substantially reducing the entropic losses associated with the phase-change process. In particular, aligning the c-axis of a hexagonal Sb(2)Te(3) layer and the 〈111〉 direction of a cubic GeTe layer in a superlattice structure creates a material in which Ge atoms can switch between octahedral sites and lower-coordination sites at the interface of the superlattice layers. Here we demonstrate GeTe/Sb(2)Te(3) interfacial phase-change memory (IPCM) data storage devices with reduced switching energies, improved write-erase cycle lifetimes and faster switching speeds.

  8. Electrochemically modulated liquid chromatography: Theoretical investigations and applications from the perspectives of chromatography and interfacial electrochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Keller, David W. [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    Electrochemically modulated liquid chromatography (EMLC) employs a conductive material as both a stationary phase for chromatographic separations and as a working electrode for performing electrochemistry experiments. This dual functionality gives EMLC the capacity to manipulate chromatographic separations by changing the potential applied (Eapp) to the stationary phase with respect to an external reference. The ability to monitor retention as a function of Eapp provides a means to chromatographically monitor electrosorption processes at solid-liquid interfaces. In this dissertation, the retention mechanism for EMLC is examined from the perspective of electrical double layer theory and interfacial thermodynamics. From the chromatographic data, it is possible to determine the interfacial excess (Λ) of a solute and changes in interfacial tension (dγ) as a function of both Eapp and the supporting electrolyte concentration. Taken together, these two experimentally manipulated parameters can be examined within the context of the Gibbs adsorption equation to delineate the contribution of a variety of interfacial properties, including the charge of solute on the stationary phase and the potential of zero charge (PZC), to the mechanism behind EMLC-based retention. The chromatographic probing of interfacial phenomena is complemented by electroanalytical experiments that exploit the ability to monitor the electronic current flowing through an EMLC column. Cyclic voltammetry and chronoamperometry of an EMLC column are used to determine the electronic performance characteristics of an EMLC column. An electrochemical flow injection analysis of a column is provided in which the current required to maintain a constant Eapp is monitored and provides a way to examine the influence that acetonitrile and supporting electrolyte composition, flow rate, column backpressure, and ionic strength have on the structure of electrified interfaces.

  9. Superfluid 3He A-B surface tension

    International Nuclear Information System (INIS)

    Bartkowiak, M.; Haley, R.P.; Fisher, S.N.; Guenault, A.M.; Pickett, G.R.; Skyba, P.

    2003-01-01

    We have made two different measurements of interfacial energies below 300 μK, at zero pressure and in magnetic fields up to 400 mT. A variable magnetic field profile allows us to stabilize and precisely manipulate the position of the A-B interface. First, we can derive the difference in wall wetting energies from the behaviour of the phase boundary as it enters and exits a stack of glass capillary tubes. Secondly, we can measure the surface tension from the level of over- or under-magnetization needed to force the interface through an aperture. These are the first surface energy measurements in high magnetic fields in the zero-temperature limit. Our results are in surprising agreement with earlier measurements at high pressure close to T c

  10. Pendant-drop method coupled to ultraviolet-visible spectroscopy: A useful tool to investigate interfacial phenomena.

    Science.gov (United States)

    Andrade, Marco A R; Favarin, Bruno; Derradi, Rafael; Bolean, Mayte; Simão, Ana Maria S; Millán, José Luis; Ciancaglini, Pietro; Ramos, Ana P

    2016-09-05

    UV-vis spectroscopy is a powerful tool to investigate surface phenomena. Surface tension measurements coupled to spectroscopic techniques can help to elucidate how the interface organization influences the electronic properties of molecules. However, appreciable sample volumes are usually necessary to achieve strong signals during conduction of experiments. This study reports on the simultaneous acquisition of surface tension data and UV-vis spectra by axisymmetric drop shape analysis (ADSA) coupled to diffuse reflectance (DRUV) spectrophotometry using a pendant microliter-drop that requires small sample volumes and low analyte concentrations. Three example systems gave evidence of the applicability of this technique: (a) disaggregation of an organic dye driven by surfactant as a function of the surface tension and alterations in the UV-vis spectra, (b) activity of a glycosylphosphatidylinositol anchored enzyme estimated from formation of a colored product, and (c) interaction between this enzyme and biomimetic membrane systems consisting of dipalmitoylphosphaditylcholine and cholestenone. Apart from using smaller sample volume, this coupled technique allowed to investigate interfacial organization in the light of electronic spectra obtained in loco within a shorter acquisition time. This procedure provided precise interfacial information about static and dynamic systems. This has been the first study describing the kinetic activity of an enzyme in the presence of phospholipid monolayers through simultaneous determination of the surface tension and UV-vis spectra.

  11. Interfacial area and interfacial transfer in two-phase systems. DOE final report

    Energy Technology Data Exchange (ETDEWEB)

    Ishii, Mamoru; Hibiki, T.; Revankar, S.T.; Kim, S.; Le Corre, J.M.

    2002-07-01

    In the two-fluid model, the field equations are expressed by the six conservation equations consisting of mass, momentum and energy equations for each phase. The existence of the interfacial transfer terms is one of the most important characteristics of the two-fluid model formulation. The interfacial transfer terms are strongly related to the interfacial area concentration and to the local transfer mechanisms such as the degree of turbulence near interfaces. This study focuses on the development of a closure relation for the interfacial area concentration. A brief summary of several problems of the current closure relation for the interfacial area concentration and a new concept to overcome the problem are given.

  12. Impact of Interfacial Characteristics on Foam Structure: Study on Model Fluids and at Pilot Scale

    Directory of Open Access Journals (Sweden)

    Mezdour Samir

    2017-03-01

    Full Text Available Foams represent an important area of research because of their relevance to many industrial processes. In continuous foaming operations, foaming ability depends on the process parameters and the characteristics of the raw materials used for foamed products. The effects of fluid viscosity and equilibrium surface tension on foam structure have been studied extensively. Furthermore, as surface active agents diffuse to the interface, they can modify other interface properties through their adsorption, such as interfacial rheology and surface tension kinetics. In order to better understand how these two interfacial properties influence foam structuring, we formulated model foaming solutions with different interface viscoelasticity levels and adsorption rates, but all with the same equilibrium surface tension and viscosity. The solutions were made up of a surface active agent and glucose syrup, so as to maintain a Newtonian behaviour. Five surface active agents were used: Whey Protein Isolate (WPI, sodium caseinate, saponin, cetyl phosphate and Sodium Dodecyl Sulphate (SDS, at concentrations ranging from 0.1% to 1%. Their molecular characteristics, and their interaction with the glucose syrup, made it possible to obtain a range of interface viscoelasticities and surface tension kinetics for these model solutions. The solutions were whipped in a continuously-operating industrial foaming device in order to control process parameters such as shearing and overrun, and to ensure that the experiment was representative of industrial production. The structure of the foams thus obtained foams was then determined by characterising bubble size using image analysis. For all the model solutions, both the viscoelastic moduli and apparent diffusion coefficient were linked to foam structure. The results showed that both high interface viscoelasticity and rapid diffusion kinetics induced a foam structure containing small bubbles. Both effects, as well as the impact of

  13. Interfacial modulation of urban affect

    DEFF Research Database (Denmark)

    Samson, Kristine

    , Massey 2006), they also exclude in depth social and human interaction. Through analysis of three examples of urban affective interfaces (The High Line in New York, Superkilen in Copenhagen and Stålsat By, Frederiksværk, the paper examines how affective urban interfaces modulate and mediate urban...

  14. Sun pipeline`s tensioned cover system saves storage costs

    Energy Technology Data Exchange (ETDEWEB)

    Blaisdell, J.R. [Sun Pipe Line Co., Detroit, MI (United States); Lydick, L. [National Seal Co., Aurora, IL (United States)

    1996-02-01

    Sun Pipe Line chose the Columbia tensioned floating cover (TFC) system from Columbia Geosystems for several reasons. First, capital costs for the TFC system are considerably lower than those for structural metal or concrete systems. Installation requires less time than fixed structures, and construction costs are about one-tenth as much. A second reason for the choice is its patented tower/tension cover design which easily accommodates fluctuating fluid levels in brine ponds, even in a rapid drawdown. When brine is pumped into the storage chambers, changes in brine ponds can be as great as ten feet. The tensioned design maintains folds of extra material on the outer perimeter of the cover above fluid level. As fluid levels fall, the curtain unfolds and adequate reservoir coverage is maintained.

  15. Analysis and modeling of low voltage electrical network at power line carrier frequencies (3-148.5 kHz); Analyse et modelisation du reseau basse tension aux frequences courants porteurs (3 KHZ-148,5 KHZ)

    Energy Technology Data Exchange (ETDEWEB)

    Duval, G.

    1998-07-01

    Electricite de France (EdF) wishes to establish a physical communication link between his clients and the EdF centres. The final link, i.e. between the high/low voltage transformation substation and the residential clients, being ensured by carrier currents. With this aim, an analysis and a modeling of the low voltage network at the carrier frequencies (3 kHz - 148.5 kHz) has been performed. This work has been carried out in parallel with an experiment involving 3500 apparatuses that use carrier currents. The diversity of the French low voltage networks and the limitations imposed by the EN50065-1 standard about the use of carrier currents in Europe do not favour the development of such carrier current systems. Disturbing voltages and localized impedances represent the main difficulties to get round. Inside accommodations, domotic carrier currents have a reduced range but a higher disturbance amplitude because of the proximity of appliances. A differential mode to common mode conversion phenomenon has been evidenced which generates network couplings and important electromagnetic fields. Energy lines and cables have been analyzed using numerical models. Load peaks have been analyzed using statistical tools in order to take into account the daily fluctuations. The modeling of the network is made in two steps: a double-wire model is considered first. Then a three-phase model is developed which analyzes the inter-phases coupling and the effect of the distribution of clients' loads on each phase. The results of this model are conformable with measurements except for underground networks. As perspectives of future works and beyond todays standard framework, the techniques that allow a sensible increase of communication flow rates have been reviewed. (J.S.)

  16. Spreading of oil films on water in the surface tension regime

    Energy Technology Data Exchange (ETDEWEB)

    Camp, D.W.

    1985-01-01

    Surface tension forces will cause an oil to spread over water if the tension of the oil film (the summed surface and interfacial tensions for bulk oil films, or the equilibrium spreading tension for monomolecular films) is less than the surface tension of water. For oil films spreading in a 40 cm long channel, measurements are made of leading edge position and lateral profiles of film thickness, velocity, and tension as a function of time. Measurements of the tension profiles, important for evaluating proposed theories, is made possible by the development of a new technique based on the Wilhelmy method. The oils studied were silicones, fatty acids and alcohols, and mixtures of surfactants in otherwise nonspreading oils. The single-component oils show an acceleration zone connecting a slow-moving inner region with a fast-moving leading monolayer. The dependence of film tension on film thickness for spreading single-component oils often differs from that at equilibrium. The mixtures show a bulk oil film configuration which extends to the leading edge and have velocity profiles which increase smoothly. The theoretical framework, similarity transformation, and asymptotic solutions of Foda and Cox for single-component oils were shown to be valid. An analysis of spreading surfactant-oil mixtures is developed which allows them to be treated under this framework. An easily-used semi-empirical model is proposed which allows them to be treated under this framework. An easily-used semi-empirical model is proposed which allows accurate prediction of detailed spreading behavior for any spreading oil.

  17. Single-Molecule Interfacial Electron Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Lu, H. Peter [Bowling Green State Univ., Bowling Green, OH (United States). Dept. of Chemistry and Center for Photochemical Sciences

    2017-11-28

    This project is focused on the use of single-molecule high spatial and temporal resolved techniques to study molecular dynamics in condensed phase and at interfaces, especially, the complex reaction dynamics associated with electron and energy transfer rate processes. The complexity and inhomogeneity of the interfacial ET dynamics often present a major challenge for a molecular level comprehension of the intrinsically complex systems, which calls for both higher spatial and temporal resolutions at ultimate single-molecule and single-particle sensitivities. Combined single-molecule spectroscopy and electrochemical atomic force microscopy approaches are unique for heterogeneous and complex interfacial electron transfer systems because the static and dynamic inhomogeneities can be identified and characterized by studying one molecule at a specific nanoscale surface site at a time. The goal of our project is to integrate and apply these spectroscopic imaging and topographic scanning techniques to measure the energy flow and electron flow between molecules and substrate surfaces as a function of surface site geometry and molecular structure. We have been primarily focusing on studying interfacial electron transfer under ambient condition and electrolyte solution involving both single crystal and colloidal TiO2 and related substrates. The resulting molecular level understanding of the fundamental interfacial electron transfer processes will be important for developing efficient light harvesting systems and broadly applicable to problems in fundamental chemistry and physics. We have made significant advancement on deciphering the underlying mechanism of the complex and inhomogeneous interfacial electron transfer dynamics in dyesensitized TiO2 nanoparticle systems that strongly involves with and regulated by molecule-surface interactions. We have studied interfacial electron transfer on TiO2 nanoparticle surfaces by using ultrafast single

  18. Mephisto: Interfacial Destabilization in Metal Alloys

    Science.gov (United States)

    Favier, J. J.; Malmejac, Y.

    1985-01-01

    The destabilizing mechanisms at a solidification interface were studied to obtain information on the kinetics and morphologies in the transient and steady state, and to separate the influences of liquid phase instabilities from interfacial instabilities. A differential seebeck voltage measurements technique was developed to provide a continuous record of the solid-liquid interface temperature as the solidification rate is varied to determine the kinetic coefficients. Signal processing and noise suppression techniques allow nonovolt precision which corresponds to mK accuracy for the interfacial temperature.

  19. Expressions of the radius and the surface tension of surface of tension in terms of the pressure distribution for nanoscale liquid threads

    International Nuclear Information System (INIS)

    Yan Hong; Wei Jiu-An; Cui Shu-Wen; Zhu Ru-Zeng

    2013-01-01

    The expressions of the radius and the surface tension of surface of tension R s and γ s in terms of the pressure distribution for nanoscale liquid threads are of great importance for molecular dynamics (MD) simulations of the interfacial phenomena of nanoscale fluids; these two basic expressions are derived in this paper. Although these expressions were derived first in the literature [Kim B G, Lee J S, Han M H, and Park S, 2006 Nanoscale and Microscale Thermophysical Engineering, 10, 283] and used widely thereafter, the derivation is wrong both in logical structure and physical thought. In view of the importance of these basic expressions, the logic and physical mistakes appearing in that derivation are pointed out. (condensed matter: structural, mechanical, and thermal properties)

  20. A Noncontact Picolitor Droplet Handling by Photothermal Control of Interfacial Flow.

    Science.gov (United States)

    Muto, Masakazu; Yamamoto, Makoto; Motosuke, Masahiro

    2016-01-01

    We present a noncontact handling of droplets in a microfluidic platform by the Marangoni convection, interfacial tension driven flow, generated by a light-induced local temperature gradient in the surrounding liquid of the droplet. Droplets flowing in a microchannel experience a force due to the interfacial tension gradient when approaching the heated area. This method provides noncontact, selective and flexible manipulation for droplets flowing in microchannel network. In this study, an O/W emulsion system with oleic acid for the dispersed phase and a buffer solution for the continuous one was used. Trajectory control and trapping for droplets with 5 - 65 pL in volume was achieved by patterned laser irradiation. Also, we quantitatively evaluated the driving force exerted on droplets by measuring the fluidic temperature distribution around the droplet. From the balance of the drag force and the photo-induced Marangoni force, the driving force was determined using the measured temperature gradient of the droplet. From the results, the applicability of noncontact droplet manipulation using the photothermal Marangoni effect by continuous-phase heating has been demonstrated.

  1. Interfacial Properties of Methylcelluloses: The Influence of Molar Mass

    Directory of Open Access Journals (Sweden)

    Pauline L. Nasatto

    2014-12-01

    Full Text Available The interfacial interactions of four methylcelluloses having the same average degree of substitution and distribution of methyl groups, but different molar masses, are studied at ambient temperature and at very low polymer concentrations. Firstly, the surface tension σ at the water/air interface is determined for the progressive addition of methylcellulose up to 100 mg/L; σ starts to decrease over 1 mg/L up to the critical aggregation concentration (CAC at 10 mg/L. The curves describing the influence of polymer concentration on σ are independent of the molar mass at equilibrium. Secondly, the adsorption of methylcellulose on silica particles is estimated from ζ-potential measurements. The data are interpreted in terms of an increase of the adsorbed layer thickness at the interface when the molar mass of methylcellulose increases. It is concluded that methylcellulose is adsorbed, forming trains and loops at the interface based on the equilibrium between surface free energy and solvent quality.

  2. Abolishing the maximum tension principle

    Directory of Open Access Journals (Sweden)

    Mariusz P. Da̧browski

    2015-09-01

    Full Text Available We find the series of example theories for which the relativistic limit of maximum tension Fmax=c4/4G represented by the entropic force can be abolished. Among them the varying constants theories, some generalized entropy models applied both for cosmological and black hole horizons as well as some generalized uncertainty principle models.

  3. Portfolios: Assumptions, Tensions, and Possibilities.

    Science.gov (United States)

    Tierney, Robert J.; Clark, Caroline; Fenner, Linda; Herter, Roberta J.; Simpson, Carolyn Staunton; Wiser, Bert

    1998-01-01

    Presents a discussion between two educators of the history, assumptions, tensions, and possibilities surrounding the use of portfolios in multiple classroom contexts. Includes illustrative commentaries that offer alternative perspectives from a range of other educators with differing backgrounds and interests in portfolios. (RS)

  4. Innovative qPCR using interfacial effects to enable low threshold cycle detection and inhibition relief

    Science.gov (United States)

    Harshman, Dustin K.; Rao, Brianna M.; McLain, Jean E.; Watts, George S.; Yoon, Jeong-Yeol

    2015-01-01

    Molecular diagnostics offers quick access to information but fails to operate at a speed required for clinical decision-making. Our novel methodology, droplet-on-thermocouple silhouette real-time polymerase chain reaction (DOTS qPCR), uses interfacial effects for droplet actuation, inhibition relief, and amplification sensing. DOTS qPCR has sample-to-answer times as short as 3 min 30 s. In infective endocarditis diagnosis, DOTS qPCR demonstrates reproducibility, differentiation of antibiotic susceptibility, subpicogram limit of detection, and thermocycling speeds of up to 28 s/cycle in the presence of tissue contaminants. Langmuir and Gibbs adsorption isotherms are used to describe the decreasing interfacial tension upon amplification. Moreover, a log-linear relationship with low threshold cycles is presented for real-time quantification by imaging the droplet-on-thermocouple silhouette with a smartphone. DOTS qPCR resolves several limitations of commercially available real-time PCR systems, which rely on fluorescence detection, have substantially higher threshold cycles, and require expensive optical components and extensive sample preparation. Due to the advantages of low threshold cycle detection, we anticipate extending this technology to biological research applications such as single cell, single nucleus, and single DNA molecule analyses. Our work is the first demonstrated use of interfacial effects for sensing reaction progress, and it will enable point-of-care molecular diagnosis of infections. PMID:26601245

  5. The influence of interfacial properties on two-phase liquid flow of organic contaminants in groundwater

    International Nuclear Information System (INIS)

    Hayes, K.F.; Demond, A.H.

    1991-09-01

    The purpose of this project is to investigate how changes in interfacial chemical properties affect two-phase transport relationships. Specifically, the objective is to develop a quantitative means that will enable the prediction of changes in the capillary pressure-saturation relationship, a fundamental constitutive relationship in multiphase flow, from changes in interfacial properties, such as adsorption and electrophoretic mobility, through a knowledge of their effect on wettability. The information presented here summarizes the progress we have made in the past eight months of the second project period. Working with a system composed of air-water-silica-cetyltrimethylammonium bromide (CTAB), we have obtained a relationship between degree of adsorption and the surface charge of silica (as measured by electrophoretic mobility), and the drainage and imbibition capillary pressure relationships of system. The bulk of this report describes the completed set of measurements for the air-water-silica-CTAB system at pH 6. We are currently working on a comparable set of measurements for the xylene-water-silica-CTAB system at pH 6. Described here are the interfacial tension, contact angle and preliminary drainage capillary pressure measurements. Our work to date shows a dependence of surface properties on pH. Consequently, in the coming year, we will also complete a set of measurements at another pH value to show the effect of pH on capillary pressure relationships

  6. CALCULATION OF TENSION FORCE OF BELT CONVEYOR

    OpenAIRE

    Ismet Ibishi; Ahmet Latifi; Gzim Ibishi; Kadri Sejdiu; Melihate Shala-Galica; Bekim Latifi

    2012-01-01

    In this paper is done the explanation on tension fashion of the belt conveyor which is employed in Kosovo Energy Corporation – KEK, for coal transportation to provide electric power plant. The aim of the paper enables to recognize tension forces not to pass with deformation of belt so that this problem will damage the workingprocess. Work principle is based on initial tension and tension during working process. The fact is known that the tension starts from the carriage on the way to tension ...

  7. Multiscale Modeling of Mesoscale and Interfacial Phenomena

    Science.gov (United States)

    Petsev, Nikolai Dimitrov

    With rapidly emerging technologies that feature interfaces modified at the nanoscale, traditional macroscopic models are pushed to their limits to explain phenomena where molecular processes can play a key role. Often, such problems appear to defy explanation when treated with coarse-grained continuum models alone, yet remain prohibitively expensive from a molecular simulation perspective. A prominent example is surface nanobubbles: nanoscopic gaseous domains typically found on hydrophobic surfaces that have puzzled researchers for over two decades due to their unusually long lifetimes. We show how an entirely macroscopic, non-equilibrium model explains many of their anomalous properties, including their stability and abnormally small gas-side contact angles. From this purely transport perspective, we investigate how factors such as temperature and saturation affect nanobubbles, providing numerous experimentally testable predictions. However, recent work also emphasizes the relevance of molecular-scale phenomena that cannot be described in terms of bulk phases or pristine interfaces. This is true for nanobubbles as well, whose nanoscale heights may require molecular detail to capture the relevant physics, in particular near the bubble three-phase contact line. Therefore, there is a clear need for general ways to link molecular granularity and behavior with large-scale continuum models in the treatment of many interfacial problems. In light of this, we have developed a general set of simulation strategies that couple mesoscale particle-based continuum models to molecular regions simulated through conventional molecular dynamics (MD). In addition, we derived a transport model for binary mixtures that opens the possibility for a wide range of applications in biological and drug delivery problems, and is readily reconciled with our hybrid MD-continuum techniques. Approaches that couple multiple length scales for fluid mixtures are largely absent in the literature, and

  8. Particle and surfactant interactions effected polar and dispersive components of interfacial energy in nanocolloids

    Science.gov (United States)

    Harikrishnan, A. R.; Das, Sarit K.; Agnihotri, Prabhat K.; Dhar, Purbarun

    2017-08-01

    We segregate and report experimentally for the first time the polar and dispersive interfacial energy components of complex nanocolloidal dispersions. In the present study, we introduce a novel inverse protocol for the classical Owens Wendt method to determine the constitutive polar and dispersive elements of surface tension in such multicomponent fluidic systems. The effect of nanoparticles alone and aqueous surfactants alone are studied independently to understand the role of the concentration of the dispersed phase in modulating the constitutive elements of surface energy in fluids. Surfactants are capable of altering the polar component, and the combined particle and surfactant nanodispersions are shown to be effective in modulating the polar and dispersive components of surface tension depending on the relative particle and surfactant concentrations as well as the morphological and electrostatic nature of the dispersed phases. We observe that the combined surfactant and particle colloid exhibits a similar behavior to that of the particle only case; however, the amount of modulation of the polar and dispersive constituents is found to be different from the particle alone case which brings to the forefront the mechanisms through which surfactants modulate interfacial energies in complex fluids. Accordingly, we are able to show that the observations can be merged into a form of quasi-universal trend in the trends of polar and dispersive components in spite of the non-universal character in the wetting behavior of the fluids. We analyze the different factors affecting the polar and dispersive interactions in such complex colloids, and the physics behind such complex interactions has been explained by appealing to the classical dispersion theories by London, Debye, and Keesom as well as by Derjaguin-Landau-Verwey-Overbeek theory. The findings shed light on the nature of wetting behavior of such complex fluids and help in predicting the wettability and the degree of

  9. Numerical Study on the Effects of Gravity and Surface Tension on Condensation Process in Square Minichannel

    Science.gov (United States)

    Li, Panpan; Chen, Zhenqian; Shi, Juan

    2017-12-01

    A volume of fluid (VOF) method is adopted to simulate the condensation of R134a in a horizontal single square minichannel with 1 mm side length. The effect of gravity, surface tension and gas-liquid interfacial shear stress are taken into account. The result denotes that condensation is first appeared at the corner of channel, and then the condensation is stretched at the effect of surface tension until the whole channel boundary covered. The effect of gravity on the distribution of the liquid film depends on the channel length. In short channel, the gravity shows no significant effect, the distribution shape of steam in the cross section of the channel is approximately circular. In long channel, due to the influence of gravity, the liquid converges at the bottom under the effect of gravity, and the thickness of the liquid film at the bottom is obviously higher than that of the upper part of the channel. The effect of surface tension on condensation is also analysed. The surface tension can enhance the condensation heat transfer significantly when the inlet mass flux is low. Whilst, at high mass flux, the enhancement of surface tension on heat transfer is unobvious and can be neglected.

  10. The Constrained Vapor Bubble Experiment - Interfacial Flow Region

    Science.gov (United States)

    Kundan, Akshay; Wayner, Peter C., Jr.; Plawsky, Joel L.

    2015-01-01

    Internal heat transfer coefficient of the CVB correlated to the presence of the interfacial flow region. Competition between capillary and Marangoni flow caused Flooding and not a Dry-out region. Interfacial flow region growth is arrested at higher power inputs. 1D heat model confirms the presence of interfacial flow region. 1D heat model confirms the arresting phenomena of interfacial flow region Visual observations are essential to understanding.

  11. The phase and interfacial properties of azeotropic refrigerants: the prediction of aneotropes from molecular theory.

    Science.gov (United States)

    Fouad, Wael A; Vega, Lourdes F

    2017-03-29

    The use of hydrofluorocarbons (HFCs) as alternative non-ozone depleting refrigerants for chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) has grown during the last couple of decades. Owing to their considerable global warming potential, a global deal has been reached recently to limit the production and consumption of HFCs. For rational design of new refrigerants that are environmentally friendlier, the thermodynamics of current ones need to be well understood first. In this work, we examine the phase behavior of azeotropic refrigerants obtained by mixing HFCs with normal alkanes. The vapor-liquid equilibria (VLE) of these binary systems exhibit positive deviation from Raoult's law in the bulk, and a negative deviation from surface ideality (aneotrope) at the interface. The phase equilibria, second order thermodynamic derivative properties and interfacial properties of these complex systems were studied here using a modified version of the Statistical Associating Fluid Theory (SAFT) combined with Density Gradient Theory (DGT). The model was able to accurately capture the azeotropic nature of the phase equilibria and predict their composition and pressure at temperatures where experimental data are limited. In addition, accurate descriptions of the interfacial tensions were also obtained when compared with available experimental data, predicting the minimum found in surface tension as a function of composition. The molecular-based theory allowed the calculation of interfacial properties for which there is no experimental data available yet. Predictions show that the aneotrope occurs at a lower HFC composition for R-152a and R-134a systems in comparison to R-143a and R-125 systems. According to the calculated density profiles, HFC molecules appear to be preferentially adsorbed at the interface causing the surface tension of the n-alkane rich phase to decrease at low HFC concentrations. At high HFC concentrations, the phenomenon is inverted and n

  12. Modeling interfacial dynamics using nonequilibrium thermodynamics frameworks

    NARCIS (Netherlands)

    Sagis, L.M.C.

    2013-01-01

    In recent years several nonequilibrium thermodynamic frameworks have been developed capable of describing the dynamics of multiphase systems with complex microstructured interfaces. In this paper we present an overview of these frameworks. We will discuss interfacial dynamics in the context of the

  13. Gelation and interfacial behaviour of vegetable proteins

    NARCIS (Netherlands)

    Vliet, van T.; Martin, A.H.; Bos, M.A.

    2002-01-01

    Recent studies on gelation and interfacial properties of vegetable proteins are reviewed. Attention is focused on legume proteins, mainly soy proteins, and on wheat proteins. The rheological properties of vegetable protein gels as a function of heating time or temperature is discussed as well as the

  14. Gelation and interfacial behaviour of vegetable proteins

    NARCIS (Netherlands)

    Vliet, T. van; Martin, A.H.; Bos, M.A.

    2002-01-01

    Recent studies on gelation and interfacial properties of vegetable protiens are reviewed. Attention is focused on legume proteins, mainly soy proteins, and on wheat proteins. The rheological properteis of vegetable protein gels as a function of heating time or temperature is discussed as well as the

  15. Interfacial properties of green leaf cellulosic particles

    NARCIS (Netherlands)

    Tamayo Tenorio, A.; Gieteling, J.; Nikiforidis, C.V.; Boom, R.M.; Goot, van der A.J.

    2017-01-01

    Cellulosic pulp from sugar beet leaves was fractionated and assessed on its interfacial properties. After pressing leaves to express the juice, the press cake was washed at alkaline pH (pH 9) to remove residual protein, dried, milled and air classified. The obtained cellulosic particles mainly

  16. Investigation of Mechanical Properties and Interfacial Mechanics of Crystalline Nanomaterials

    Science.gov (United States)

    Qin, Qingquan

    Nanowires (NWs) and nanotubes (NTs) are critical building blocks of nanotechnologies. The operation and reliability of these nanomaterials based devices depend on their mechanical properties of the nanomaterials, which is therefore important to accurately measure the mechanical properties. Besides, the NW--substrate interfaces also play a critical role in both mechanical reliability and electrical performance of these nanodevices, especially when the size of the NW is small. In this thesis, we focus on the mechanical properties and interface mechanics of three important one dimensional (1D) nanomaterials: ZnO NWs, Ag NWs and Si NWs. For the size effect study, this thesis presents a systematic experimental investigation on the elastic and failure properties of ZnO NWs under different loading modes: tension and buckling. Both tensile modulus (from tension) and bending modulus (from buckling) were found to increase as the NW diameter decreased from 80 to 20 nm. The elastic modulus also shows loading mode dependent; the bending modulus increases more rapidly than the tensile modulus. The tension experiments showed that fracture strain and strength of ZnO NWs increase as the NW diameter decrease. A resonance testing setup was developed to measure elastic modulus of ZnO NWs to confirm the loading mode dependent effect. A systematic study was conducted on the effect of clamping on resonance frequency and thus measured Young's modulus of NWs via a combined experiment and simulation approach. A simple scaling law was provided as guidelines for future designs to accurate measure elastic modulus of a cantilevered NW using the resonance method. This thesis reports the first quantitative measurement of a full spectrum of mechanical properties of five-fold twinned Ag NWs including Young's modulus, yield strength and ultimate tensile strength. In situ tensile testing of Ag NWs with diameters between 34 and 130 nm was carried out inside a SEM. Young's modulus, yield strength and

  17. Single-Molecule Interfacial Electron Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Wilson [Univ. of California, Irvine, CA (United States)

    2018-02-03

    Interfacial electron transfer (ET) plays an important role in many chemical and biological processes. Specifically, interfacial ET in TiO2-based systems is important to solar energy technology, catalysis, and environmental remediation technology. However, the microscopic mechanism of interfacial ET is not well understood with regard to atomic surface structure, molecular structure, bonding, orientation, and motion. In this project, we used two complementary methodologies; single-molecule fluorescence spectroscopy, and scanning-tunneling microscopy and spectroscopy (STM and STS) to address this scientific need. The goal of this project was to integrate these techniques and measure the molecular dependence of ET between adsorbed molecules and TiO2 semiconductor surfaces and the ET induced reactions such as the splitting of water. The scanning probe techniques, STM and STS, are capable of providing the highest spatial resolution but not easily time-resolved data. Single-molecule fluorescence spectroscopy is capable of good time resolution but requires further development to match the spatial resolution of the STM. The integrated approach involving Peter Lu at Bowling Green State University (BGSU) and Wilson Ho at the University of California, Irvine (UC Irvine) produced methods for time and spatially resolved chemical imaging of interfacial electron transfer dynamics and photocatalytic reactions. An integral aspect of the joint research was a significant exchange of graduate students to work at the two institutions. This project bridged complementary approaches to investigate a set of common problems by working with the same molecules on a variety of solid surfaces, but using appropriate techniques to probe under ambient (BGSU) and ultrahigh vacuum (UCI) conditions. The molecular level understanding of the fundamental interfacial electron transfer processes obtained in this joint project will be important for developing efficient light harvesting

  18. Tensions of Corporate Social Responsibility

    DEFF Research Database (Denmark)

    Strand, Robert

    I engaged with the top management team (TMT) and employees of American Cafes Corporation as an action/intervention researcher in the 20 months immediately following the TMT’s decision to formalize the company’s corporate social responsibility (CSR) activities. This led to the establishment...... CSR agenda is considered, which brings with it a multiplicity of substantively rational ends for which the corporation could pursue. I show the CSR bureaucracy can create a space for reflection in which the multiplicity of substantively rational ends can be considered, negotiated, and selected...... for reflection within the corporation. But I also show tensions can arise from the establishment of the CSR bureaucracy itself. This suggests the CSR bureaucracy itself resides in a tension....

  19. Robust Tensioned Kevlar Suspension Design

    Science.gov (United States)

    Young, Joseph B.; Naylor, Bret J.; Holmes, Warren A.

    2012-01-01

    One common but challenging problem in cryogenic engineering is to produce a mount that has excellent thermal isolation but is also rigid. Such mounts can be achieved by suspending the load from a network of fibers or strings held in tension. Kevlar fibers are often used for this purpose owing to their high strength and low thermal conductivity. A suite of compact design elements has been developed to improve the reliability of suspension systems made of Kevlar.

  20. 29 CFR 1926.955 - Overhead lines.

    Science.gov (United States)

    2010-07-01

    ... installing or removing wire or cable, strains to which poles and structures will be subjected shall be... being strung in or removed shall be kept under positive control by the use of adequate tension reels... adjacent to energized lines the tension stringing method or other methods which preclude unintentional...

  1. Line Tension and Wettability of Nanodrops on Curved Surfaces

    NARCIS (Netherlands)

    Maheshwari, Shantanu; van der Hoef, Martin Anton; Lohse, Detlef

    2016-01-01

    In this work we study the formation of nanodrops on curved surfaces (both convex and concave) by means of molecular dynamics simulations, where the particles interact via a Lennard-Jones potential. We find that the contact angle is not affected by the curvature of the substrate, in agreement with

  2. On interfacial properties of tetrahydrofuran: Atomistic and coarse-grained models from molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Garrido, J. M. [Departamento de Ingeniería Química, Universidad de Concepción, POB 160-C Concepción (Chile); Algaba, J.; Blas, F. J., E-mail: felipe@uhu.es [Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Física Aplicada, Universidad de Huelva, 21007 Huelva (Spain); Míguez, J. M. [Laboratoire des Fluides Complexes et Leurs Reservoirs, Université de Pau et des Pays de l’Adour, CNRS, TOTAL–UMR 5150, Avenue de l’Université, B.P. 1155, Pau F-64013 (France); Departamento de Física Aplicada, Universidade de Vigo, E36310 Vigo (Spain); Mendiboure, B. [Laboratoire des Fluides Complexes et Leurs Reservoirs, Université de Pau et des Pays de l’Adour, CNRS, TOTAL–UMR 5150, Avenue de l’Université, B.P. 1155, Pau F-64013 (France); Moreno-Ventas Bravo, A. I. [Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Geología, Universidad de Huelva, 21007 Huelva (Spain); Piñeiro, M. M. [Departamento de Física Aplicada, Universidade de Vigo, E36310 Vigo (Spain)

    2016-04-14

    We have determined the interfacial properties of tetrahydrofuran (THF) from direct simulation of the vapor-liquid interface. The molecules are modeled using six different molecular models, three of them based on the united-atom approach and the other three based on a coarse-grained (CG) approach. In the first case, THF is modeled using the transferable parameters potential functions approach proposed by Chandrasekhar and Jorgensen [J. Chem. Phys. 77, 5073 (1982)] and a new parametrization of the TraPPE force fields for cyclic alkanes and ethers [S. J. Keasler et al., J. Phys. Chem. B 115, 11234 (2012)]. In both cases, dispersive and coulombic intermolecular interactions are explicitly taken into account. In the second case, THF is modeled as a single sphere, a diatomic molecule, and a ring formed from three Mie monomers according to the SAFT-γ Mie top-down approach [V. Papaioannou et al., J. Chem. Phys. 140, 054107 (2014)]. Simulations were performed in the molecular dynamics canonical ensemble and the vapor-liquid surface tension is evaluated from the normal and tangential components of the pressure tensor along the simulation box. In addition to the surface tension, we have also obtained density profiles, coexistence densities, critical temperature, density, and pressure, and interfacial thickness as functions of temperature, paying special attention to the comparison between the estimations obtained from different models and literature experimental data. The simulation results obtained from the three CG models as described by the SAFT-γ Mie approach are able to predict accurately the vapor-liquid phase envelope of THF, in excellent agreement with estimations obtained from TraPPE model and experimental data in the whole range of coexistence. However, Chandrasekhar and Jorgensen model presents significant deviations from experimental results. We also compare the predictions for surface tension as obtained from simulation results for all the models with

  3. Interfacial pH-gradient induced micro-capillary filling with the aid of transverse electrodes arrays in presence of electrical double layer effects

    International Nuclear Information System (INIS)

    Jain, Avi; Chakraborty, Suman

    2010-01-01

    In the present work, we outline the design and analysis of a micro-capillary filling mechanism through the aid of interfacial pH gradients (and hence interfacial tension gradients) generated by employing arrays of transverse electrodes inducing step changes in voltages, in a natural buffer system that requires low power and no synthetic ampholytes. The capillary transport is modulated by a dynamic and non-trivial coupling between the interfacial tension and viscous resistances, as a consequence of the underlying intermolecular interactions. The competing effects of the driving and the retarding forces effectively determine the displacement, velocity and acceleration characteristics of the capillary front, in a dynamically evolving manner. A comprehensive theoretical model of capillary dynamics is developed here to address these issues in details, thereby revealing the combined influence of the interfacial electrochemistry and the applied transverse voltages, as guided by the pertinent fundamental thermodynamic principles governed by free energy considerations and the physico-chemical phenomena over interfacial scales. Non-trivial implications of the pH-gradient driven micro-capillary transport are aptly emphasized, so as to offer significant physical insights on the adopted strategy as a guiding principle for facilitating capillary filling processes by inducing a modulation in the effective interfacial energy. Particular implications on the capillary filling time are also pinpointed, revealing the effectiveness of the adopted design strategy. Finally, a universal scaling relationship of the capillary filling time as a function of the pertinent operating parameters is derived, so as to provide a generalized guideline for implementing the design scheme. A non-dimensional parameter, depending simultaneously on the inter-electrode pitch and the transverse voltage, is identified, which may be kept to a minimal limit within the other operating constraints of the chosen

  4. Surface tension of decane binary and ternary mixtures with eicosane, docosane, and tetracosane

    DEFF Research Database (Denmark)

    Queimada, Antonio; Cao, A.I.; Marrucho, I.M.

    2005-01-01

    -C24H50 and the ternary n-C10H22 + n-C20H42 + n-C24H50 were measured from 293.15 K (or above the solution melting temperature) up to 343.15 K. An average absolute deviation of 1.3% was obtained in comparison with pure component literature data. No mixture information for the reported systems was found......A tensiometer operating on the Wilhelmy plate method was employed to measure liquid-vapor interfacial tensions of three binary mixtures and one ternary mixture of decane with eicosane, docosane, and tetracosane. Tensions of binary mixtures n-C10H22 + n-C20H42, n-C10H22 + n-C22H46, and n-C10H22 + n...

  5. Frontiers of interfacial water research :workshop report.

    Energy Technology Data Exchange (ETDEWEB)

    Cygan, Randall Timothy; Greathouse, Jeffery A.

    2005-10-01

    Water is the critical natural resource of the new century. Significant improvements in traditional water treatment processes require novel approaches based on a fundamental understanding of nanoscale and atomic interactions at interfaces between aqueous solution and materials. To better understand these critical issues and to promote an open dialog among leading international experts in water-related specialties, Sandia National Laboratories sponsored a workshop on April 24-26, 2005 in Santa Fe, New Mexico. The ''Frontiers of Interfacial Water Research Workshop'' provided attendees with a critical review of water technologies and emphasized the new advances in surface and interfacial microscopy, spectroscopy, diffraction, and computer simulation needed for the development of new materials for water treatment.

  6. Mesoscale Interfacial Dynamics in Magnetoelectric Nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Shashank, Priya [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2009-12-14

    Biphasic composites are the key towards achieving enhanced magnetoelectric response. In order understand the control behavior of the composites and resultant symmetry of the multifunctional product tensors, we need to synthesized model material systems with the following features (i) interface formation through either deposition control or natural decomposition; (ii) a very high interphase-interfacial area, to maximize the ME coupling; and (iii) an equilibrium phase distribution and morphology, resulting in preferred crystallographic orientation relations between phases across the interphase-interfacial boundaries. This thought process guided the experimental evolution in this program. We initiated the research with the co-fired composites approach and then moved on to the thin film laminates deposited through the rf-magnetron sputtering and pulsed laser deposition process

  7. Mapping interfacial excess in atom probe data

    International Nuclear Information System (INIS)

    Felfer, Peter; Scherrer, Barbara; Demeulemeester, Jelle; Vandervorst, Wilfried; Cairney, Julie M.

    2015-01-01

    Using modern wide-angle atom probes, it is possible to acquire atomic scale 3D data containing 1000 s of nm 2 of interfaces. It is therefore possible to probe the distribution of segregated species across these interfaces. Here, we present techniques that allow the production of models for interfacial excess (IE) mapping and discuss the underlying considerations and sampling statistics. We also show, how the same principles can be used to achieve thickness mapping of thin films. We demonstrate the effectiveness on example applications, including the analysis of segregation to a phase boundary in stainless steel, segregation to a metal–ceramic interface and the assessment of thickness variations of the gate oxide in a fin-FET. - Highlights: • Using computational geometry, interfacial excess can be mapped for various features in APT. • Suitable analysis models can be created by combining manual modelling and mesh generation algorithms. • Thin film thickness can be mapped with high accuracy using this technique.

  8. Interfacial friction damping properties in magnetorheological elastomers

    International Nuclear Information System (INIS)

    Fan, Yanceng; Gong, Xinglong; Xuan, Shouhu; Zhang, Wei; Zheng, Jian; Jiang, Wanquan

    2011-01-01

    In this study, the interfacial friction damping properties of magnetorheological elastomers (MREs) were investigated experimentally. Two kinds of carbonyl iron particles, with sizes of 1.1 µm and 9.0 µm, were used to fabricate four MRE samples, whose particle weight fractions were 10%, 30%, 60% and 80%, respectively. Their microstructures were observed using an environmental scanning electron microscope (SEM). The dynamic performances of these samples, including shear storage modulus and loss factor were measured with a modified dynamic mechanical analyzer (DMA). The experimental results indicate that MRE samples fabricated with 1.1 µm carbonyl iron particles have obvious particle agglomeration, which results in the fluctuation of loss factor compared with other MRE samples fabricated with large particle sizes. The analysis implies that the interfacial friction damping mainly comes from the frictional sliding at the interfaces between the free rubber and the particles

  9. Interfacial Fluid Mechanics A Mathematical Modeling Approach

    CERN Document Server

    Ajaev, Vladimir S

    2012-01-01

    Interfacial Fluid Mechanics: A Mathematical Modeling Approach provides an introduction to mathematical models of viscous flow used in rapidly developing fields of microfluidics and microscale heat transfer. The basic physical effects are first introduced in the context of simple configurations and their relative importance in typical microscale applications is discussed. Then,several configurations of importance to microfluidics, most notably thin films/droplets on substrates and confined bubbles, are discussed in detail.  Topics from current research on electrokinetic phenomena, liquid flow near structured solid surfaces, evaporation/condensation, and surfactant phenomena are discussed in the later chapters. This book also:  Discusses mathematical models in the context of actual applications such as electrowetting Includes unique material on fluid flow near structured surfaces and phase change phenomena Shows readers how to solve modeling problems related to microscale multiphase flows Interfacial Fluid Me...

  10. Facile Interfacial Electron Transfer of Hemoglobin

    Directory of Open Access Journals (Sweden)

    Chunhai Fan

    2005-12-01

    Full Text Available Abstract: We herein describe a method of depositing hemoglobin (Hb and sulfonated polyaniline (SPAN on GC electrodes that facilitate interfacial protein electron transfer. Well-defined, reproducible, chemically reversible peaks of Hb and SPAN can be obtained in our experiments. We also observed enhanced peroxidase activity of Hb in SPAN films. These results clearly showed that SPAN worked as molecular wires and effectively exchanged electrons between Hb and electrodes.Mediated by Conjugated Polymers

  11. Interfacially driven transport in narrow channels

    OpenAIRE

    Bacchin, Patrice

    2018-01-01

    When colloids flow in a narrow channel, the transport efficiency is controlled by the non-equilibrium interplay between colloid-wall interactions and hydrodynamics. In this paper, a general, unifying description of colloidal dispersion flow in a confined system is proposed. A momentum and mass balance founded framework implementing the colloid-interface interactions is introduced. The framework allows us to depict how interfacial forces drive the particles and the liquid flows. The interfacia...

  12. The effect of surface tension reduction on the clinical performance of sodium hypochlorite in endodontics.

    Science.gov (United States)

    Rossi-Fedele, G; Prichard, J W; Steier, L; de Figueiredo, J A P

    2013-06-01

    Sodium hypochlorite (NaOCl) is recommended as an endodontic irrigant in view of its broad antimicrobial and tissue dissolution capacities. To enhance its penetration into inaccessible areas of root canals and to improve its overall effect, the addition of surface-active agents has been suggested. The aim of this investigation was to review the effect of the reduction of the surface tension on the performance of NaOCl in endodontics. A search was performed in the Medline electronic database (articles published up to 28 July 2012, in English) with the search terms and combinations as follows: 'sodium hypochlorite AND surface tension or interfacial force or interfacial tension or surface-active agent or amphiphilic agent or surface active agent or surfactant or tenside or detergent'. The purpose of this search was to identify publications that compared NaOCl alone and NaOCl modified with the addition of a surface-active agent in endodontics. A hand search of articles published online ('in-press' and 'early view'), and appearing in the reference list of the articles included, was further performed, using the same search criteria as the electronic search. The search identified 302 publications, of which 11 fulfilled the inclusion/exclusion criteria of the review. The evidence available suggests that surface-active agents improve the penetration of NaOCl in the main canal and have no effect on its pulp tissue dissolution ability. There are, however, insufficient data to enable a sound conclusion to be drawn regarding the effect of modifying NaOCl's surface tension on lubrication, antimicrobial and smear layer or debris removal abilities. © 2012 International Endodontic Journal.

  13. Phenylephrine Decreases Vascular Tension in Goat Arteries in Specific Circumstances.

    Directory of Open Access Journals (Sweden)

    Renu R Raj

    Full Text Available Phenylephrine (PE causes vasoconstriction through alpha adrenergic receptors. PE-induced vasodilatation has also been reported earlier in pre-constricted vessels. Here we demonstrate in spiral strips of goat arteries that addition of PE can decrease tone even from base-line levels (i.e. not pre-constricted and show that this process requires nitric oxide (NO and alpha adrenergic stimulation, but is cGMP-independent. Under control conditions, PE caused vasoconstriction, but under conditions where NO levels are higher, as with L-Arginine or sodium nitroprusside, PE decreased vessel tension. L-Arginine/PE combination was not able to decrease tension when alpha adrenoceptors were blocked with Phentolamine or endothelial nitric oxide synthase (eNOS was blocked with Nω-Nitro-L-arginine (L-NNA. Propranolol, a beta blocker, was unable to prevent the reduction in tension by the L-Arginine/PE combination. Adrenaline and noradrenaline (and not isoproterenol also reduced vessel tension in the presence of L-Arginine. Even when NO levels were not enhanced, relieving NO from having to stimulate the enzyme soluble guanylyl cyclase (sGC (either by using sGC blockers, namely ODQ or methylene blue, or by enhancing cGMP levels (with sildenafil which by negative feedback probably inhibits sGC led to PE-induced reduction of vascular tension. PMA-phorbol myristate acetate-an agonist which stimulates Protein Kinase C was able to prevent the ability of PE to reduce vascular tension in a high NO environment. Our conclusion is that PE reduces vascular tension through alpha adrenoceptors if there is excess NO availability to activate a putative pathway. Though the reduction of vessel tone by PE is dependent on NO, it is independent of cGMP. Prior treatment with PMA or PE itself can prevent further PE-induced reduction of tension in a high NO environment. The results here suggest, counter-intuitively, that alpha blockers may be of help in the treatment of septic shock

  14. Arresting dissolution by interfacial rheology design

    Science.gov (United States)

    Beltramo, Peter J.; Gupta, Manish; Alicke, Alexandra; Liascukiene, Irma; Gunes, Deniz Z.; Baroud, Charles N.

    2017-01-01

    A strategy to halt dissolution of particle-coated air bubbles in water based on interfacial rheology design is presented. Whereas previously a dense monolayer was believed to be required for such an “armored bubble” to resist dissolution, in fact engineering a 2D yield stress interface suffices to achieve such performance at submonolayer particle coverages. We use a suite of interfacial rheology techniques to characterize spherical and ellipsoidal particles at an air–water interface as a function of surface coverage. Bubbles with varying particle coverages are made and their resistance to dissolution evaluated using a microfluidic technique. Whereas a bare bubble only has a single pressure at which a given radius is stable, we find a range of pressures over which bubble dissolution is arrested for armored bubbles. The link between interfacial rheology and macroscopic dissolution of ∼ 100 μm bubbles coated with ∼ 1 μm particles is presented and discussed. The generic design rationale is confirmed by using nonspherical particles, which develop significant yield stress at even lower surface coverages. Hence, it can be applied to successfully inhibit Ostwald ripening in a multitude of foam and emulsion applications. PMID:28893993

  15. Liquid-liquid interfacial properties of a symmetrical Lennard-Jones binary mixture

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Ruiz, F. J.; Blas, F. J., E-mail: felipe@uhu.es [Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Física Aplicada, Universidad de Huelva, 21007 Huelva (Spain); Moreno-Ventas Bravo, A. I. [Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Geología, Universidad de Huelva, 21007 Huelva (Spain)

    2015-09-14

    We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, σ{sub 11} = σ{sub 22}, with the same dispersive energy between like species, ϵ{sub 11} = ϵ{sub 22}, but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janecek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances r{sub c} and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance r{sub c} is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related

  16. Origen de la Cefalea Tensional

    OpenAIRE

    Romero Godoy, Rosalinda; Romero Godoy, Sara Raquel

    2010-01-01

    Introducción y objetivos: La cefalea es una de las causas de consulta médica más comunes y el síntoma más frecuente consultado en neurología. La prevalencia según estudios estadísticos nacionales es de un 62% en hombres y un 86% en mujeres. De todas las cefaleas la cefalea tensional es la más común, pero la menos estudiada y conocida. Nos hemos propuesto hacer una revisión actual sobre la etiopatogenia en las cefaleas tensionales que nos pueda orientar a futuras investigaciones. ...

  17. Quantitative estimation of the parameters for self-motion driven by difference in surface tension.

    Science.gov (United States)

    Suematsu, Nobuhiko J; Sasaki, Tomohiro; Nakata, Satoshi; Kitahata, Hiroyuki

    2014-07-15

    Quantitative information on the parameters associated with self-propelled objects would enhance the potential of this research field; for example, finding a realistic way to develop a functional self-propelled object and quantitative understanding of the mechanism of self-motion. We therefore estimated five main parameters, including the driving force, of a camphor boat as a simple self-propelled object that spontaneously moves on water due to difference in surface tension. The experimental results and mathematical model indicated that the camphor boat generated a driving force of 4.2 μN, which corresponds to a difference in surface tension of 1.1 mN m(-1). The methods used in this study are not restricted to evaluate the parameters of self-motion of a camphor boat, but can be applied to other self-propelled objects driven by difference in surface tension. Thus, our investigation provides a novel method to quantitatively estimate the parameters for self-propelled objects driven by the interfacial tension difference.

  18. Update on normal tension glaucoma

    Directory of Open Access Journals (Sweden)

    Jyotiranjan Mallick

    2016-01-01

    Full Text Available Normal tension glaucoma (NTG is labelled when typical glaucomatous disc changes, visual field defects and open anterior chamber angles are associated with intraocular pressure (IOP constantly below 21 mmHg. Chronic low vascular perfusion, Raynaud's phenomenon, migraine, nocturnal systemic hypotension and over-treated systemic hypertension are the main causes of normal tension glaucoma. Goldmann applanation tonometry, gonioscopy, slit lamp biomicroscopy, optical coherence tomography and visual field analysis are the main tools of investigation for the diagnosis of NTG. Management follows the same principles of treatment for other chronic glaucomas: To reduce IOP by a substantial amount, sufficient to prevent disabling visual loss. Treatment is generally aimed to lower IOP by 30% from pre-existing levels to 12-14 mmHg. Betaxolol, brimonidine, prostaglandin analogues, trabeculectomy (in refractory cases, systemic calcium channel blockers (such as nifedipine and 24-hour monitoring of blood pressure are considered in the management of NTG. The present review summarises risk factors, causes, pathogenesis, diagnosis and management of NTG.

  19. Simultaneous measurement of surface tension and viscosity using freely decaying oscillations of acoustically levitated droplets

    Science.gov (United States)

    Kremer, J.; Kilzer, A.; Petermann, M.

    2018-01-01

    Oscillations of small liquid drops around a spherical shape have been of great interest to scientists measuring physical properties such as interfacial tension and viscosity, over the last few decades. A powerful tool for contactless positioning is acoustic levitation, which has been used to simultaneously determine the surface tension and viscosity of liquids at ambient pressure. In order to extend this acoustic levitation measurement method to high pressure systems, the method is first evaluated under ambient pressure. To measure surface tension and viscosity using acoustically levitated oscillating drops, an image analysis method has to be developed and factors which may affect measurement, such as sound field or oscillation amplitude, have to be analyzed. In this paper, we describe the simultaneous measurement of surface tension and viscosity using freely decaying shape oscillations of acoustically levitated droplets of different liquids (silicone oils AK 5 and AK 10, squalane, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol) in air. These liquids vary in viscosity from 2 to about 30 mPa s. An acoustic levitation system, including an optimized standing wave acoustic levitator and a high-speed camera, was used for this study. An image analysis was performed with a self-written Matlab® code. The frequency of oscillation and the damping constant, required for the determination of surface tension and viscosity, respectively, were calculated from the evolution of the equatorial and polar radii. The results and observations are compared to data from the literature in order to analyze the accuracy of surface tension and viscosity determination, as well as the effect of non-spherical drop shape or amplitude of oscillation on measurement.

  20. Simultaneous measurement of surface tension and viscosity using freely decaying oscillations of acoustically levitated droplets.

    Science.gov (United States)

    Kremer, J; Kilzer, A; Petermann, M

    2018-01-01

    Oscillations of small liquid drops around a spherical shape have been of great interest to scientists measuring physical properties such as interfacial tension and viscosity, over the last few decades. A powerful tool for contactless positioning is acoustic levitation, which has been used to simultaneously determine the surface tension and viscosity of liquids at ambient pressure. In order to extend this acoustic levitation measurement method to high pressure systems, the method is first evaluated under ambient pressure. To measure surface tension and viscosity using acoustically levitated oscillating drops, an image analysis method has to be developed and factors which may affect measurement, such as sound field or oscillation amplitude, have to be analyzed. In this paper, we describe the simultaneous measurement of surface tension and viscosity using freely decaying shape oscillations of acoustically levitated droplets of different liquids (silicone oils AK 5 and AK 10, squalane, 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, and 1-octanol) in air. These liquids vary in viscosity from 2 to about 30 mPa s. An acoustic levitation system, including an optimized standing wave acoustic levitator and a high-speed camera, was used for this study. An image analysis was performed with a self-written Matlab® code. The frequency of oscillation and the damping constant, required for the determination of surface tension and viscosity, respectively, were calculated from the evolution of the equatorial and polar radii. The results and observations are compared to data from the literature in order to analyze the accuracy of surface tension and viscosity determination, as well as the effect of non-spherical drop shape or amplitude of oscillation on measurement.

  1. FEM Modeling of In-Plane Stress Distribution in Thick Brittle Coatings/Films on Ductile Substrates Subjected to Tensile Stress to Determine Interfacial Strength

    Directory of Open Access Journals (Sweden)

    Kaishi Wang

    2018-03-01

    Full Text Available The ceramic-metal interface is present in various material structures and devices that are vulnerable to failures, like cracking, which are typically due to their incompatible properties, e.g., thermal expansion mismatch. In failure of these multilayer systems, interfacial shear strength is a good measure of the robustness of interfaces, especially for planar films. There is a widely-used shear lag model and method by Agrawal and Raj to analyse and measure the interfacial shear strength of thin brittle film on ductile substrates. The use of this classical model for a type of polymer derived ceramic coatings (thickness ~18 μm on steel substrate leads to high values of interfacial shear strength. Here, we present finite element simulations for such a coating system when it is subjected to in-plane tension. Results show that the in-plane stresses in the coating are non-uniform, i.e., varying across the thickness of the film. Therefore, they do not meet one of the basic assumptions of the classical model: uniform in-plane stress. Furthermore, effects of three significant parameters, film thickness, crack spacing, and Young’s modulus, on the in-plane stress distribution have also been investigated. ‘Thickness-averaged In-plane Stress’ (TIS, a new failure criterion, is proposed for estimating the interfacial shear strength, which leads to a more realistic estimation of the tensile strength and interfacial shear strength of thick brittle films/coatings on ductile substrates.

  2. Scaling of interfacial jump conditions; Escalamiento de condiciones de salto interfacial

    Energy Technology Data Exchange (ETDEWEB)

    Quezada G, S.; Vazquez R, A.; Espinosa P, G., E-mail: sequga@gmail.com [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Area de Ingenieria en Recursos Energeticos, Apdo. Postal 55-535, 09340 Ciudad de Mexico (Mexico)

    2015-09-15

    To model the behavior of a nuclear reactor accurately is needed to have balance models that take into account the different phenomena occurring in the reactor. These balances have to be coupled together through boundary conditions. The boundary conditions have been studied and different treatments have been given to the interface. In this paper is a brief description of some of the interfacial jump conditions that have been proposed in recent years. Also, the scaling of an interfacial jump condition is proposed, for coupling the different materials that are in contact within a nuclear reactor. (Author)

  3. Adsorption of ionic surfactants at microscopic air-water interfaces using the micropipette interfacial area-expansion method

    DEFF Research Database (Denmark)

    Kinoshita, Koji; Parra, Elisa; Needham, David

    2017-01-01

    The dynamic adsorption of ionic surfactants at air-water interfaces have been less-well studied than that of the simpler non-ionics since experimental limitations on dynamic surface tension (DST) measurements create inconsistencies in their kinetic analysis. Using our newly designed "Micropipette...... interfacial area-expansion method", we have measured and evaluated both equilibrium and dynamic adsorption of a well-known anionic surfactant, sodium dodecyl sulphate (SDS), in the absence or presence of 100mM NaCl. Our focus was to determine if and to what extent the inclusion of a new correction parameter...... for the "ideal ionic activity", A±i, can renormalize both equilibrium and dynamic surface tension measurements and provide better estimates of the diffusion coefficient of ionic surfactants in aqueous media obtained from electroneutral models, namely extended Frumkin isotherm and Ward-Tordai adsorption models...

  4. The study and design of tension controller

    Science.gov (United States)

    Jun, G.; Lamei, X.

    2018-02-01

    Tension control is a wide used technology in areas such as textiles, paper and plastic films. In this article, the tension control system release and winding process is analyzed and the mathematical model of tension control system is established, and a high performance tension controller is designed. In hardware design, STM32F130 single chip microcomputer is used as the control core, which has the characteristics of fast running speed and rich peripheral features. In software design, μC/OS-II operating system is introduced to improve the efficiency of single chip microcomputer, and enhance the independence of each module, and make development and maintenance more convenient. The taper tension control is adopted in the winding part, which can effectively solve the problem of rolling shrinkage. The results show that the tension controller has the characteristics of simple structure, easy operation and stable performance.

  5. Fluid-fluid interfacial mobility from random walks

    Science.gov (United States)

    Barclay, Paul L.; Lukes, Jennifer R.

    2017-12-01

    Dual control volume grand canonical molecular dynamics is used to perform the first calculation of fluid-fluid interfacial mobilities. The mobility is calculated from one-dimensional random walks of the interface by relating the diffusion coefficient to the interfacial mobility. Three different calculation methods are employed: one using the interfacial position variance as a function of time, one using the mean-squared interfacial displacement, and one using the time-autocorrelation of the interfacial velocity. The mobility is calculated for two liquid-liquid interfaces and one liquid-vapor interface to examine the robustness of the methods. Excellent agreement between the three calculation methods is shown for all the three interfaces, indicating that any of them could be used to calculate the interfacial mobility.

  6. Impact of oil type and WPI/Tween 80 ratio at the oil-water interface: Adsorption, interfacial rheology and emulsion features.

    Science.gov (United States)

    Gomes, Andresa; Costa, Ana Letícia Rodrigues; Cunha, Rosiane Lopes

    2018-04-01

    The relationship between the composition and structure of food emulsions was evaluated from the effect of a mixture of emulsifiers Whey protein (WPI) - Tween 80 (T80) and the oil phase features, such as chain length and unsaturation degree (sunflower oil, a long chain triacylglycerol - LCT or NEOBEE ® 1053, a medium chain triacylglycerol - MCT). Emulsions with LCT showed higher droplet size than MCT as a consequence of its higher viscosity. All emulsions exhibited shear thinning behavior, but the viscosity was influenced by their interface composition. An occurrence of the destabilization mechanism by creaming was observed in turbidimetric measurements, but no visual phase separation could be observed, indicating a good kinetic stability after a 7-day storage. The initial interfacial tension of the water-LCT or water-MCT oil was about 25 mN/m, but the WPI addition (1% w/w) reduced the initial interfacial tension to approximately 20 mN/m. The increase of T80 concentration led to a decrease of the interfacial tension, reaching a value around 10 mN/m in systems with pure T80. The curves of interfacial tension of systems with LCT or MCT showed differences in the decay rate of tension over time. These differences were attributed to characteristics of the oil phase (hydrophobicity, unsaturation degree, presence of impurities) and the different proportions of each emulsifier within the mixture of emulsifiers. Finally, a higher viscoelastic interface was observed in LCT emulsions, which were mainly stabilized by WPI molecules. Such molecules presented a higher resistance to the displacement due to the competitive adsorption phenomenon, since the LCT is a more hydrophobic oil. On the other hand, the interface with MCT and a higher T80 concentration was less viscoelastic due to an easier displacement of WPI from the interface and the replacement by T80. The results indicate that T80 can be used in combination with WPI to produce emulsions with good stability and lower

  7. Measurement of local interfacial area concentration in boiling loop

    International Nuclear Information System (INIS)

    Kyoung, Ho Kang; Byong, Jo Yun; Goon, Cherl Park

    1995-01-01

    An accurate prediction of two-phase flow is essential to many energy systems, including nuclear reactors. To model the two-phase flow, detailed information on the internal flow structure is required. The void fraction and interfacial area concentration are important fundamental parameters characterizing the internal structure of two-phase flow. The interfacial area concentration is defined as the available interfacial area per unit volume of the two-phase mixture in calculations of the interfacial transport of mass, momentum, and energy. Although a number of studies have been made in this area, the interfacial area concentration in two-phase flow has not been sufficiently investigated either experimentally or analytically. Most existing models for interfacial area concentration are limited to area-averaged interfacial area concentration in a flow channel. And the studies on local interfacial area concentration are limited to the case of air-water two-phase flow. However, the internal flow structure of steam-water two-phase flow having various bubble sizes could be quite different from that of air-water two-phase flow, the reliability of which weak in practical applications. In this study, the local interfacial area concentration steam-water two-phase flow has been investigated experimentally in a circular boiling tube having a heating rod in the center, and for the low flow with liquid superficial velocity <1 m/s

  8. Development of Interfacial Structure in a Confined Air-Water Cap-Turbulent and Churn-Turbulent Flow

    International Nuclear Information System (INIS)

    Xiaodong Sun; Seungjin Kim; Ling Cheng; Mamoru Ishii; Beus, Stephen G.

    2002-01-01

    The objective of the present work is to study and model the interfacial structure development of air-water two-phase flow in a confined test section. Experiments of a total of 9 flow conditions in cap-turbulent and churn-turbulent flow regimes are carried out in a vertical air-water upward two-phase flow experimental loop with a test section of 200-mm in width and 10-mm in gap. Miniaturized four-sensor conductivity probes are used to measure local two-phase parameters at three different elevations for each flow condition. The bubbles captured by the probes are categorized into two groups in view of the two-group interfacial area transport equation, i.e., spherical/distorted bubbles as Group 1 and cap/churn-turbulent bubbles as Group 2. The acquired parameters are time-averaged local void fraction, interfacial velocity, bubble number frequency, interfacial area concentration, and bubble Sauter mean diameter for both groups of bubbles. Also, the line-averaged and area-averaged data are presented and discussed. The comparisons of these parameters at different elevations demonstrate the development of interfacial structure along the flow direction due to bubble interactions. (authors)

  9. Interfacial properties of Quillaja saponins and its use for micellisation of lutein esters.

    Science.gov (United States)

    Tippel, Janine; Lehmann, Maren; von Klitzing, Regine; Drusch, Stephan

    2016-12-01

    Natural food colourants, colouring foods and bioactive food ingredients need to be solubilised for their incorporation in food. Aim of the present study was to investigate the micelle-forming properties of saponins from Quillaja saponaria Mollina (QS) in order to solubilise a lutein ester extract for its incorporation in food matrices. QS showed a high surface activity and functionality with respect to micellisation as derived from interfacial tension measurements and subsequent data fitting to the classical Frumkin model. The composition of the aqueous phase affected the lutein ester incorporation as revealed by particle size, zeta potential and colour measurements. In terms of morphology of lutein ester loaded saponin micelles (LMS), cryo-TEM micrographs showed depending on the composition of the medium both, spherical and elongated branched micelles. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. The Plastic Tension Field Method

    DEFF Research Database (Denmark)

    Hansen, Thomas

    2005-01-01

    . The emphasis is attached to the presentation of a design method based on the diagonal tension field theory. Also, how to determine the load-carrying capacity of a given steel plate girder with transverse web stiffeners, is briefly presented. The load-carrying capacity may be predicted by applying both...... method. The method is based on the theory of plasticity and is analogous to the so-called diagonal compression field method developed for reinforced concrete beams with transverse stirrups, which is adopted in the common European concrete code (Eurocode 2). Many other theories have been developed......, but the method presented differs from these theories by incorporating the strength of the transverse stiffeners and by the assumption that the tensile bands may pass the transverse stiffeners, which often is observed in tests. Other methods have only dealt with a single web field between two stiffeners...

  11. Interfacial fluid dynamics and transport processes

    CERN Document Server

    Schwabe, Dietrich

    2003-01-01

    The present set of lectures and tutorial reviews deals with various topical aspects related to instabilities of interfacial processes and driven flows from both the theoretical and experimental point of views. New research has been spurred by the many demands for applications in material sciences (melting, solidification, electro deposition), biomedical engineering and processing in microgravity environments. This book is intended as both a modern source of reference for researchers in the field as well as an introduction to postgraduate students and non-specialists from related areas.

  12. Measuring Interfacial Polymerization Kinetics Using Microfluidic Interferometry.

    Science.gov (United States)

    Nowbahar, Arash; Mansard, Vincent; Mecca, Jodi M; Paul, Mou; Arrowood, Tina; Squires, Todd M

    2018-03-07

    A range of academic and industrial fields exploit interfacial polymerization in producing fibers, capsules, and films. Although widely used, measurements of reaction kinetics remain challenging and rarely reported, due to film thinness and reaction rapidity. Here, polyamide film formation is studied using microfluidic interferometry, measuring monomer concentration profiles near the interface during the reaction. Our results reveal that the reaction is initially controlled by a reaction-diffusion boundary layer within the organic phase, which allows the first measurements of the rate constant for this system.

  13. Viscosity of interfacial water regulates ice nucleation

    International Nuclear Information System (INIS)

    Li, Kaiyong; Chen, Jing; Zhang, Qiaolan; Zhang, Yifan; Xu, Shun; Zhou, Xin; Cui, Dapeng; Wang, Jianjun; Song, Yanlin

    2014-01-01

    Ice formation on solid surfaces is an important phenomenon in many fields, such as cloud formation and atmospheric icing, and a key factor for applications in preventing freezing. Here, we report temperature-dependent nucleation rates of ice for hydrophilic and hydrophobic surfaces. The results show that hydrophilic surface presents a lower ice nucleation rate. We develop a strategy to extract the thermodynamic parameters, J 0 and Γ, in the context of classical nucleation theory. From the extracted J 0 and Γ, we reveal the dominant role played by interfacial water. The results provide an insight into freezing mechanism on solid surfaces

  14. Giant flexoelectric effect through interfacial strain relaxation.

    Science.gov (United States)

    Lee, Daesu; Noh, Tae Won

    2012-10-28

    Interfacial strain gradients in oxide epitaxial thin films provide an interesting opportunity to study flexoelectric effects and their potential applications. Oxide epitaxial thin films can exhibit giant and tunable flexoelectric effects, which are six or seven orders of magnitude larger than those in conventional bulk solids. The strain gradient in an oxide epitaxial thin film can generate an electric field above 1 MV m(-1) by flexoelectricity, large enough to affect the physical properties of the film. Giant flexoelectric effects on ferroelectric properties are discussed in this overview of recent experimental observations.

  15. Neutron reflectometry for interfacial materials characterization

    International Nuclear Information System (INIS)

    Lin, Eric K.; Pochan, Darrin J.; Kolb, Rainer; Wu Wenli; Satija, Sushil K.

    1998-01-01

    Neutron reflectometry provides a powerful non-destructive analytic technique to measure physical properties of interfacial materials. The sample reflectivity provides information about composition, thickness, and roughness of films with 0.1 nm resolution. The use of neutrons has the additional advantage of being able to label selected atomic species by using different isotopes. Two examples are presented to demonstrate the use of neutron reflectometry in measuring the thermal expansion of a buried thin polymer film and measuring the change in polymer mobility near a solid substrate

  16. Adsorption induced losses in interfacial cohesion

    International Nuclear Information System (INIS)

    Asaro, R.J.

    1977-07-01

    A model for interfacial cohesion is developed which describes the loss in the strength of an interface due to the segregation and adsorption of impurities on it. Distinctions are made between interface separations that occur too rapidly for any significant redistribution of adsorbing matter to take place and separations that are slow enough to allow full adsorption equilibrium. Expressions for the total work of complete decohesion are presented for both cases. The results are applied to well-known model adsorption isotherms and some experimental data for grain boundary adsorption of phosphorus in iron is analyzed with respect to the losses in intergranular cohesion

  17. Interfacial Behavior of Polymers: Using Interfaces to Manipulate Polymers

    Energy Technology Data Exchange (ETDEWEB)

    Russell, Thomas P. [Univ. of Massachusetts, Amherst, MA (United States). Dept. of Polymer Science and Engineering

    2015-02-26

    most rapid solvent removal process drives the copolymer film to below its glass transition temperature, freezing in the lateral order. We have quantitatively described the ordering and the parameters influencing the disruption of the ordering in these studies. We have also used e-beam lithography to generate shallow trench patterns on planar surface where the topographic patterning provides an additional constraint on the self-assembly of the block copolymer. The pitches of the trenches were varied while the depth and the trench width of patterns were maintained by constant at 89 and 30nm, respectively. Unidirectional PS-b-PEO line patterns over large area on the shallow trench patterns were obtained by solvent vapor annealing. We extended the solvent annealing process to an in-line coating process using a mini-slot die coater developed in our laboratories. This coater uses minimal materials with operating parameters that can mimic actual industrial processing on a roll-to-roll line. Most important, with this mini-slot die coater, it could also characterize the structure of the film using grazing incidence x-ray scattering. Using the fundamental characterization of the ordering of the block copolymers, we could optimize the coating conditions to enhance lateral ordering of block copolymer in a well-defined manner. The structures produced in this process are directly transferable to flexible electronics where the arrays of block copolymer microdomains can be used for the fabrication of nanostructured components. We have also controlled the orientation of BCP microdomains at the air and substrate interfaces by manipulating the interfacial interactions with selective solvents. This has enabled us to generate nanoporous membranes where the size of the pores is dictated by the size of the bloc copolymer microdomains. We have produced robust nanoporous membranes that can tolerate high pressures and have high throughput using thick films of block copolymers. Exceptional size

  18. Surfactant induced complex formation and their effects on the interfacial properties of seawater.

    Science.gov (United States)

    Guzmán, Eduardo; Santini, Eva; Benedetti, Alessandro; Ravera, Francesca; Ferrari, Michele; Liggieri, Libero

    2014-11-01

    The effect of a cationic surfactant, hexadecyltrimethylammonium bromide (CTAB), on the interfacial properties of seawater has been studied by dynamic and equilibrium surface tension and by dilational rheology essays. Important modifications of the surface tension and dilational rheology response have been observed already at the very low CTAB concentrations, where the effects due to the high ionic strength are negligible. The comparison with the effects of CTAB in different seawater models, or in natural seawater fractions, points out the establishment of strong interactions between the surfactant molecules and the lipophilic fraction of organic material dispersed/dissolved in seawater, affecting the interfacial activity of the molecules. Considering the biochemical richness of seawater, these results can be explained assuming interaction mechanisms and adsorption schemes similar to those speculated for protein and other macromolecules in the presence of surfactants, which in fact show similar features. Thus already at the low concentrations the surfactant molecules form highly surface-active complexes with part of the organic fraction of seawater. At the larger surfactant concentrations these complexes compete for adsorption with an excess of free CTAB molecules which, according to the thermodynamic conditions, are most favoured to occupy the liquid interface. The results of this study underline the important role of the sea organic content in enhancing the surface-activity of surfactants, which is relevant for a deeper understand of the direct and indirect effects of these types of pollutants on the physico-chemical environment in the sea coastal areas and develop mitigation strategies. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Engineering Interfacial Processes at Mini-Micro-Nano Scales Using Sessile Droplet Architecture.

    Science.gov (United States)

    Bansal, Lalit; Sanyal, Apratim; Kabi, Prasenjit; Pathak, Binita; Basu, Saptarshi

    2018-03-01

    Evaporating sessile functional droplets act as the fundamental building block that controls the cumulative outcome of many industrial and biological applications such as surface patterning, 3D printing, photonic crystals, and DNA sequencing, to name a few. Additionally, a drying single sessile droplet forms a high-throughput processing technique using low material volume which is especially suitable for medical diagnosis. A sessile droplet also provides an elementary platform to study and analyze fundamental interfacial processes at various length scales ranging from macroscopically observable wetting and evaporation to microfluidic transport to interparticle forces operating at a nanometric length scale. As an example, to ascertain the quality of 3D printing we must understand the fundamental interfacial processes at the droplet scale. In this article, we review the coupled physics of evaporation flow-contact-line-driven particle transport in sessile colloidal droplets and provide methodologies to control the same. Through natural alterations in droplet vaporization, one can change the evaporative pattern and contact line dynamics leading to internal flow which will modulate the final particle assembly in a nontrivial fashion. We further show that control over particle transport can also be exerted by external stimuli which can be thermal, mechanical oscillations, vapor confinement (walled or a fellow droplet), or chemical (surfactant-induced) in nature. For example, significant augmentation of an otherwise evaporation-driven particle transport in sessile droplets can be brought about simply through controlled interfacial oscillations. The ability to control the final morphologies by manipulating the governing interfacial mechanisms in the precursor stages of droplet drying makes it perfectly suitable for fabrication-, mixing-, and diagnostic-based applications.

  20. Mapping interfacial excess in atom probe data

    Energy Technology Data Exchange (ETDEWEB)

    Felfer, Peter, E-mail: peter.felfer@sydney.edu.au [School of Aerospace Mechanical and Mechatronic Engineering, The University of Sydney (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney (Australia); Scherrer, Barbara [Australian Centre for Microscopy and Microanalysis, The University of Sydney (Australia); Eidgenossische Technische Hochschule Zürich (Switzerland); Demeulemeester, Jelle [Imec vzw, Kapeldreef 75, Heverlee 3001 (Belgium); Vandervorst, Wilfried [Imec vzw, Kapeldreef 75, Heverlee 3001 (Belgium); Instituut voor Kern- en Stralingsfysica, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven (Belgium); Cairney, Julie M. [School of Aerospace Mechanical and Mechatronic Engineering, The University of Sydney (Australia); Australian Centre for Microscopy and Microanalysis, The University of Sydney (Australia)

    2015-12-15

    Using modern wide-angle atom probes, it is possible to acquire atomic scale 3D data containing 1000 s of nm{sup 2} of interfaces. It is therefore possible to probe the distribution of segregated species across these interfaces. Here, we present techniques that allow the production of models for interfacial excess (IE) mapping and discuss the underlying considerations and sampling statistics. We also show, how the same principles can be used to achieve thickness mapping of thin films. We demonstrate the effectiveness on example applications, including the analysis of segregation to a phase boundary in stainless steel, segregation to a metal–ceramic interface and the assessment of thickness variations of the gate oxide in a fin-FET. - Highlights: • Using computational geometry, interfacial excess can be mapped for various features in APT. • Suitable analysis models can be created by combining manual modelling and mesh generation algorithms. • Thin film thickness can be mapped with high accuracy using this technique.

  1. Embracing Tensions in Feminist Organizational Communication Pedagogies

    Science.gov (United States)

    Linabary, Jasmine R.; Long, Ziyu; Mouton, Ashton; Rao, Ranjani L.; Buzzanell, Patrice M.

    2017-01-01

    Feminist pedagogies hold potential to create more inclusive and transformative classrooms. Adopting a tension-centered approach, we draw on our individual and collective reflections on the design and instruction of a multi-section undergraduate organizational communication course to build an autoethnographic account of the tensions associated with…

  2. Surface tension measurements with a smartphone

    Science.gov (United States)

    Goy, Nicolas-Alexandre; Denis, Zakari; Lavaud, Maxime; Grolleau, Adrian; Dufour, Nicolas; Deblais, Antoine; Delabre, Ulysse

    2017-11-01

    Smartphones are increasingly used in higher education and at university in mechanics, acoustics, and even thermodynamics as they offer a unique way to do simple science experiments. In this article, we show how smartphones can be used in fluid mechanics to measure surface tension of various liquids, which could help students understand the concept of surface tension through simple experiments.

  3. Intraoperative Development of Tension Pneumocephalus in a ...

    African Journals Online (AJOL)

    Rapid buildup of gas within the cranial vault can result in a life‑threatening condition known as “tension pneumocephalus,” necessitating immediate surgical intervention. Nitrous oxide (N2O), a commonly used inhaled anesthetic, is associated with the development of tension pneumocephalus and its role in neurosurgical ...

  4. Tension Pneumothorax following an Accidental Kerosene Poisoning ...

    African Journals Online (AJOL)

    Tension pneumothorax is a rare complication following an accidental kerosene poisoning. In such situation, a bed-side needle thoracocentesis is performed because of its potential of becoming fatal; hence its clinical importance. A case of 15 month old boy with tension pneumothorax following accidental kerosene ...

  5. Traumatic tension pneumocephalus: Two case reports

    Directory of Open Access Journals (Sweden)

    Abubaker Al-Aieb

    2017-01-01

    Conclusions: These are two rare cases with posttraumatic tension pneumocephalus treated conservatively with a favorable outcome. Early diagnosis of tension pneumocephalus is a crucial step to facilitate early recovery; however, the associated injuries need attention as they could influence the hospital course.

  6. Tension and robustness in multitasking cellular networks.

    Directory of Open Access Journals (Sweden)

    Jeffrey V Wong

    Full Text Available Cellular networks multitask by exhibiting distinct, context-dependent dynamics. However, network states (parameters that generate a particular dynamic are often sub-optimal for others, defining a source of "tension" between them. Though multitasking is pervasive, it is not clear where tension arises, what consequences it has, and how it is resolved. We developed a generic computational framework to examine the source and consequences of tension between pairs of dynamics exhibited by the well-studied RB-E2F switch regulating cell cycle entry. We found that tension arose from task-dependent shifts in parameters associated with network modules. Although parameter sets common to distinct dynamics did exist, tension reduced both their accessibility and resilience to perturbation, indicating a trade-off between "one-size-fits-all" solutions and robustness. With high tension, robustness can be preserved by dynamic shifting of modules, enabling the network to toggle between tasks, and by increasing network complexity, in this case by gene duplication. We propose that tension is a general constraint on the architecture and operation of multitasking biological networks. To this end, our work provides a framework to quantify the extent of tension between any network dynamics and how it affects network robustness. Such analysis would suggest new ways to interfere with network elements to elucidate the design principles of cellular networks.

  7. Initial tension loss in cerclage cables.

    Science.gov (United States)

    Ménard, Jérémie; Émard, Maxime; Canet, Fanny; Brailovski, Vladimir; Petit, Yvan; Laflamme, George Y

    2013-10-01

    Cerclage cables, frequently used in the management of fractures and osteotomies, are associated with a high failure rate and significant loosening during surgery. This study compared the capacity to maintain tension of different types of orthopaedic cable systems. Multifilament Cobalt-Chrome (CoCr) cables with four different crimp/clamp devices (DePuy, Stryker, Zimmer and Smith&Nephew) and one non-metallic Nylon (Ny) cable from Kinamed were instrumented with a load cell to measure tension during insertion. Significant tension loss was observed with crimping for all cables (Ptensioner led to an additional unexpected tension loss (CoCr-DePuy: 18%, CoCr-Stryker: 29%, CoCr-Smith&Nephew: 33%, Ny: 46%, and CoCr-Zimmer: 52%). The simple CoCr (DePuy) cable system outperformed the more sophisticated locking devices due to its significantly better ability to prevent tension loss. Copyright © 2013 Elsevier Inc. All rights reserved.

  8. Rapid optimization of tension distribution for cable-driven parallel manipulators with redundant cables

    Science.gov (United States)

    Ouyang, Bo; Shang, Weiwei

    2016-03-01

    The solution of tension distributions is infinite for cable-driven parallel manipulators(CDPMs) with redundant cables. A rapid optimization method for determining the optimal tension distribution is presented. The new optimization method is primarily based on the geometry properties of a polyhedron and convex analysis. The computational efficiency of the optimization method is improved by the designed projection algorithm, and a fast algorithm is proposed to determine which two of the lines are intersected at the optimal point. Moreover, a method for avoiding the operating point on the lower tension limit is developed. Simulation experiments are implemented on a six degree-of-freedom(6-DOF) CDPM with eight cables, and the results indicate that the new method is one order of magnitude faster than the standard simplex method. The optimal distribution of tension distribution is thus rapidly established on real-time by the proposed method.

  9. Manipulation of interfacial instabilities by using a soft, deformable ...

    Indian Academy of Sciences (India)

    Multilayer flows are oftensusceptible to interfacial instabilities caused due to jump in viscosity/elasticity across thefluid–fluid interface. It is frequently required to manipulate and control these interfacial instabilities in various applications such as coating processes or polymer coextrusion. We demonstrate here the possibility ...

  10. Studying bacterial hydrophobicity and biofilm formation at liquid-liquid interfaces through interfacial rheology and pendant drop tensiometry.

    Science.gov (United States)

    Rühs, P A; Böcker, L; Inglis, R F; Fischer, P

    2014-05-01

    Bacterial adsorption to interfaces is a key factor in biofilm formation. One major limitation to understanding biofilm formation and development is the accurate measurement of bacterial cell adhesion to hydrophobic interfaces. With this study, bacterial attachment and biofilm growth over time at water-oil interface was monitored through interfacial rheology and tensiometry. Five model bacteria (Pseudomonas putida KT2442, Pseudomonas putida W2, Salmonella typhimurium, Escherichia coli, and Bacillus subtilis) were allowed to adsorb at the water-oil interface either in their non-growing or growing state. We found that we were able to observe the initial kinetics of bacterial attachment and the transient biofilm formation at the water-oil interface through interfacial rheology and tensiometry. Electrophoretic mobility measurements and bacterial adhesion to hydrocarbons (BATH) tests were performed to characterize the selected bacteria. To validate interfacial rheology and tensiometry measurements, we monitored biofilm formation utilizing both confocal laser scanning microscopy and light microscopy. Using this combination of techniques, we were able to observe the elasticity and tension development over time, from the first bacterial attachment up to biofilm formation. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Choroidal Excavation in Eye with Normal Tension Glaucoma

    Directory of Open Access Journals (Sweden)

    Kazunobu Asao

    2014-05-01

    Full Text Available Purpose: To report the case of an eye with normal tension glaucoma and a choroidal excavation. Methods: This is an observational case report. Results: A 59-year-old woman with normal tension glaucoma had a choroidal excavation in the left eye. Her best-corrected visual acuity and intraocular pressure were within normal limits and had been stable for 5 years. Fundus examination showed a small white lesion inferior to the macula and a nerve fiber layer defect at the inferior edge of the optic disc. Humphrey Field Analyzer (HFA showed visual field defects corresponding to the nerve fiber layer defect with C30-2, and a central scotoma superior to the macula with C10-2. Optical coherence tomography (OCT showed a 150-µm deep choroidal excavation. Disruptions of the IS/OS line were detected only in the area inferior to the choroidal excavation. During the 5 months of follow-up, her best-corrected visual acuity remained at 1.0 and the IOP ranged from 12 to 14 mm Hg in the left eye. The fundus and OCT images did not deteriorate and the choroidal excavation did not enlarge. Conclusions: The disruption of the inner/outer segment (IS/OS line was detected only at the area surrounding the choroidal excavation. OCT examinations are useful in assessing the area of the residual IS/OS line, and HFA can be used to estimate the residual central visual field.

  12. Design and construction of the tensioned ties for UX15 cavern vault

    CERN Document Server

    Parkin, R J H

    2002-01-01

    Due to the programme constraints for the UX15 cavern set by CERN, it has been necessary to complete the concrete lining of the vault prior to the excavation of the bench. The vault lining is therefore being temporarily suspended from a number of pre-tensioned high capacity multi-strand tensioned ties. During excavation of the bench, additional loads will be imposed onto the vault lining due to ground displacements. In order to minimise the number of ties, the previously completed linings of the PX14 and PX16 access shafts will be used to support some of the load. Three-dimensional modelling has been undertaken to design the structures and determine the expected behaviour of this complex support system. Geotechnical instrumentation has been installed in the concrete linings and the ground to monitor loads and displacements during construction. After the cavern walls have been completed, the ties will be released.

  13. Dynamical modeling of surface tension

    International Nuclear Information System (INIS)

    Brackbill, J.U.; Kothe, D.B.

    1996-01-01

    In a recent review it is said that free-surface flows ''represent some of the difficult remaining challenges in computational fluid dynamics''. There has been progress with the development of new approaches to treating interfaces, such as the level-set method and the improvement of older methods such as the VOF method. A common theme of many of the new developments has been the regularization of discontinuities at the interface. One example of this approach is the continuum surface force (CSF) formulation for surface tension, which replaces the surface stress given by Laplace's equation by an equivalent volume force. Here, we describe how CSF might be made more useful. Specifically, we consider a derivation of the CSF equations from a minimization of surface energy as outlined by Jacqmin. This reformulation suggests that if one eliminates the computation of curvature in terms of a unit normal vector, parasitic currents may be eliminated For this reformulation to work, it is necessary that transition region thickness be controlled. Various means for this, in addition to the one discussed by Jacqmin are discussed

  14. Moving contact lines in partial wetting: bridging the gap across the scales

    Science.gov (United States)

    Pahlavan, Amir; Cueto-Felgueroso, Luis; McKinley, Gareth; Juanes, Ruben

    2017-11-01

    The spreading and dewetting of liquid films on solid substrates is a common phenomenon in nature and industry from a snail secreting a mucosal film to printing and coating processes. A quantitative description of these phenomena, however, requires a detailed understanding of the flow physics at the nanoscale as the intermolecular interactions become important close to the contact line. Classical hydrodynamic theory describes wetting as an interplay between viscous and interfacial forces, neglecting the intermolecular interactions, leading to a paradox known as the moving contact line singularity. By contrast, molecular kinetic theory describes wetting as an activated process, neglecting the bulk hydrodynamics in the spreading viscous fluid film altogether. Here, we show that our recently developed model for thin liquid films in partial wetting, which properly incorporates the role of van der Waals interactions in a thin spreading fluid layer into a height-dependent surface tension, bridges the gap between these two approaches and leads to a unified framework for the description of wetting phenomena. We further use our model to investigate the instability and dewetting of nanometric liquid films, and show that it brings theoretical predictions closer to experimental observations.

  15. Wettability of AFM tip influences the profile of interfacial nanobubbles

    Science.gov (United States)

    Teshima, Hideaki; Takahashi, Koji; Takata, Yasuyuki; Nishiyama, Takashi

    2018-02-01

    To accurately characterize the shape of interfacial nanobubbles using atomic force microscopy (AFM), we investigated the effect of wettability of the AFM tip while operating in the peak force tapping (PFT) mode. The AFM tips were made hydrophobic and hydrophilic by Teflon AF coating and oxygen plasma treatment, respectively. It was found that the measured base radius of nanobubbles differed between AFM height images and adhesion images, and that this difference depended on the tip wettability. The force curves obtained during the measurements were also different depending on the wettability, especially in the range of the tip/nanobubble interaction and in the magnitude of the maximum attractive force in the retraction period. The difference suggests that hydrophobic tips penetrate the gas/liquid interface of the nanobubbles, with the three phase contact line being pinned on the tip surface; hydrophilic tips on the other hand do not penetrate the interface. We then quantitatively estimated the pinning position and recalculated the true profiles of the nanobubbles by comparing the height images and adhesion images. As the AFM tip was made more hydrophilic, the penetration depth decreased and eventually approached zero. This result suggests that the PFT measurement using a hydrophilic tip is vital for the acquisition of reliable nanobubble profiles.

  16. Interfacial transport alone accounts for coffee-ring deposition

    Science.gov (United States)

    Vandadi, Vahid; Jafari Kang, Saeed; Felske, James D.; Masoud, Hassan

    2016-11-01

    When a colloidal sessile droplet dries on a substrate, the suspended particles usually deposit on the surface in a ring-like pattern. The phenomenon is commonly known as the "coffee-ring" effect and it is widely believed to stem from the transport of solutes towards the pinned contact line by the evaporation-induced flow inside the drop. It is, therefore, assumed that the liquid-gas interface does not play an active role in shaping the deposition pattern. Here, we propose an alternative mechanism for the coffee-ring deposition, in which the particles first intersect the receding free surface and then are transported along the interface until they deposit at the edge. That the interface "captures" the solutes as the evaporation proceeds is supported by a Lagrangian tracking of particles advected by the flow field within the droplet. We model the interfacial adsorption and transport of particles by a one-dimensional advection-generation equation in a toroidal coordinate system and show that the theory adequately accounts for the coffee-ring effect. Using this model, we study the final deposition pattern on hydrophilic and hydrophobic surfaces under diffusive and uniform evaporation fluxes.

  17. Do uniform tangential interfacial stresses enhance adhesion?

    Science.gov (United States)

    Menga, Nicola; Carbone, Giuseppe; Dini, Daniele

    2018-03-01

    We present theoretical arguments, based on linear elasticity and thermodynamics, to show that interfacial tangential stresses in sliding adhesive soft contacts may lead to a significant increase of the effective energy of adhesion. A sizable expansion of the contact area is predicted in conditions corresponding to such scenario. These results are easily explained and are valid under the assumptions that: (i) sliding at the interface does not lead to any loss of adhesive interaction and (ii) spatial fluctuations of frictional stresses can be considered negligible. Our results are seemingly supported by existing experiments, and show that frictional stresses may lead to an increase of the effective energy of adhesion depending on which conditions are established at the interface of contacting bodies in the presence of adhesive forces.

  18. Interfacial Widths of Conjugated Polymer Bilayers

    Energy Technology Data Exchange (ETDEWEB)

    NCSU; UC Berkeley; UCSB; Advanced Light Source; Garcia, Andres; Yan, Hongping; Sohn, Karen E.; Hexemer, Alexander; Nguyen, Thuc-Quyen; Bazan, Guillermo C.; Kramer, Edward J.; Ade, Harald

    2009-08-13

    The interfaces of conjugated polyelectrolyte (CPE)/poly[2-methoxy-5-(2{prime}-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) bilayers cast from differential solvents are shown by resonant soft X-ray reflectivity (RSoXR) to be very smooth and sharp. The chemical interdiffusion due to casting is limited to less than 0.6 nm, and the interface created is thus nearly 'molecularly' sharp. These results demonstrate for the first time and with high precision that the nonpolar MEH-PPV layer is not much disturbed by casting the CPE layer from a polar solvent. A baseline is established for understanding the role of interfacial structure in determining the performance of CPE-based polymer light-emitting diodes. More broadly, we anticipate further applications of RSoXR as an important tool in achieving a deeper understanding of other multilayer organic optoelectronic devices, including multilayer photovoltaic devices.

  19. Liquid-liquid interfacial nanoparticle assemblies

    Science.gov (United States)

    Emrick, Todd S [South Deerfield, MA; Russell, Thomas P [Amherst, MA; Dinsmore, Anthony [Amherst, MA; Skaff, Habib [Amherst, MA; Lin, Yao [Amherst, MA

    2008-12-30

    Self-assembly of nanoparticles at the interface between two fluids, and methods to control such self-assembly process, e.g., the surface density of particles assembling at the interface; to utilize the assembled nanoparticles and their ligands in fabrication of capsules, where the elastic properties of the capsules can be varied from soft to tough; to develop capsules with well-defined porosities for ultimate use as delivery systems; and to develop chemistries whereby multiple ligands or ligands with multiple functionalities can be attached to the nanoparticles to promote the interfacial segregation and assembly of the nanoparticles. Certain embodiments use cadmium selenide (CdSe) nanoparticles, since the photoluminescence of the particles provides a convenient means by which the spatial location and organization of the particles can be probed. However, the systems and methodologies presented here are general and can, with suitable modification of the chemistries, be adapted to any type of nanoparticle.

  20. An interfacial stress sensor for biomechanical applications

    International Nuclear Information System (INIS)

    Sundara-Rajan, K; Bestick, A; Rowe, G I; Mamishev, A V; Klute, G K; Ledoux, W R; Wang, H C

    2012-01-01

    This paper presents a capacitive sensor that measures interfacial forces in prostheses and is promising for other biomedical applications. These sensors can be integrated into prosthetic devices to measure both normal and shear stress simultaneously, allowing for the study of prosthetic limb fit, and ultimately for the ability to better adapt prosthetics to individual users. A sensing cell with a 1.0 cm 2 spatial resolution and a measurement range of 0–220 kPa of shear and 0–2 MPa of pressure was constructed. The cell was load tested and found to be capable of isolating the applied shear and pressure forces. This paper discusses the construction of the prototype, the mechanical and electrode design, fabrication and characterization. The work presented is aimed at creating a class of adaptive prosthetic interfaces using a capacitive sensor. (paper)

  1. Sulfonated methyl esters of fatty acids in aqueous solutions: Interfacial and micellar properties.

    Science.gov (United States)

    Danov, Krassimir D; Stanimirova, Rumyana D; Kralchevsky, Peter A; Basheva, Elka S; Ivanova, Veronika I; Petkov, Jordan T

    2015-11-01

    The interest to sulfonated methyl esters of fatty acids (SME) has been growing during the last decade, because these surfactants are considered as an environmentally friendly and renewable alternative of the linear alkyl-benzene sulfonates (LAS). Here, we present a quantitative study on the properties of aqueous SME solutions, and especially on their surface tension isotherms, critical micelle concentration (CMC) and its dependence on the concentration of added NaCl. It is demonstrated that the CMC of an ionic surfactant determined by electrical conductivity is insensitive to the presence of a small nonionic admixture, so that the CMC values determined by conductivity represent the CMC of the pure surfactant. Using SME as an example, we have demonstrated the application of a new and powerful method for determining the physicochemical parameters of the pure ionic surfactant by theoretical data analysis ("computer purification") if the used surfactant sample contains nonionic admixtures, which are present as a rule. This method involves fits of the experimental data for surface tension and conductivity by a physicochemical model based on a system of mass-balance, chemical-equilibrium and electric-double-layer equations, which allows us to determine the adsorption and micellization parameters of C12-, C14-, C16- and C18-SME, as well the fraction of nonionic admixtures (if any). Having determined these parameters, we can further predict the interfacial and micellization properties of the surfactant solutions, such as surface tension, adsorption, degree of counterion binding, and surface electric potential at every surfactant, salt and co-surfactant concentrations. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. SWCNT Composites, Interfacial Strength and Mechanical Properties

    DEFF Research Database (Denmark)

    Ma, Jing; Larsen, Mikael

    2013-01-01

    Abstract: Single-Walled Carbon Nanotubes (SWCNT) have despite the superior mechanical properties not fully lived up to the promise as reinforcement in SWCNT composites. The strain transfer from matrix to carbon nanotubes (CNT) is poorly understood and is caused by both fewer localized strong bond...... is applied to the composite materials. The effect of polymer matrix, modification and concentration of the CNTs are discussed. The strain transfer i.e. 2D band shift under tension is compared to the mechanical properties of the SWCNT composite material....

  3. Interfacial dislocation motion and interactions in single-crystal superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Liu, B. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Raabe, D. [Max Planck Inst. fur Eisenforshung. Dusseldorf (Germany); Roters, F. [Max Planck Inst. fur Eisenforshung. Dusseldorf (Germany); Arsenlis, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-10-01

    The early stage of high-temperature low-stress creep in single-crystal superalloys is characterized by the rapid development of interfacial dislocation networks. Although interfacial motion and dynamic recovery of these dislocation networks have long been expected to control the subsequent creep behavior, direct observation and hence in-depth understanding of such processes has not been achieved. Incorporating recent developments of discrete dislocation dynamics models, we simulate interfacial dislocation motion in the channel structures of single-crystal superalloys, and investigate how interfacial dislocation motion and dynamic recovery are affected by interfacial dislocation interactions and lattice misfit. Different types of dislocation interactions are considered: self, collinear, coplanar, Lomer junction, glissile junction, and Hirth junction. The simulation results show that strong dynamic recovery occurs due to the short-range reactions of collinear annihilation and Lomer junction formation. The misfit stress is found to induce and accelerate dynamic recovery of interfacial dislocation networks involving self-interaction and Hirth junction formation, but slow down the steady interfacial motion of coplanar and glissile junction forming dislocation networks. The insights gained from these simulations on high-temperature low-stress creep of single-crystal superalloys are also discussed.

  4. Water-in-model oil emulsions studied by small-angle neutron scattering: interfacial film thickness and composition.

    Science.gov (United States)

    Verruto, Vincent J; Kilpatrick, Peter K

    2008-11-18

    composition at pH 10 versus pH 7, along with unique dynamic interfacial tension profiles, suggested that the protonation state of carboxylic moieties within asphaltenes impacts the final film properties. This was further supported when we characterized similar asphaltenic emulsions that also contained 9-anthracence carboxylic acid (ACA). Addition of this aromatic acid led to slightly thinner films (70-80 A) that were characteristically more aqueous (up to 20% by volume) and 5-6% (v/v) ACA. This unique in situ characterization (deduced entirely from SANS data from emulsion samples) of the entire film composition calls for further investigation regarding the role this film-based water plays in emulsion stability.

  5. The Role of Shearing Energy and Interfacial Gibbs Free Energy in the Emulsification Mechanism of Waxy Crude Oil

    Directory of Open Access Journals (Sweden)

    Zhihua Wang

    2017-05-01

    Full Text Available Crude oil is generally produced with water, and the water cut produced by oil wells is increasingly common over their lifetime, so it is inevitable to create emulsions during oil production. However, the formation of emulsions presents a costly problem in surface process particularly, both in terms of transportation energy consumption and separation efficiency. To deal with the production and operational problems which are related to crude oil emulsions, especially to ensure the separation and transportation of crude oil-water systems, it is necessary to better understand the emulsification mechanism of crude oil under different conditions from the aspects of bulk and interfacial properties. The concept of shearing energy was introduced in this study to reveal the driving force for emulsification. The relationship between shearing stress in the flow field and interfacial tension (IFT was established, and the correlation between shearing energy and interfacial Gibbs free energy was developed. The potential of the developed correlation model was validated using the experimental and field data on emulsification behavior. It was also shown how droplet deformation could be predicted from a random deformation degree and orientation angle. The results indicated that shearing energy as the energy produced by shearing stress working in the flow field is the driving force activating the emulsification behavior. The deformation degree and orientation angle of dispersed phase droplet are associated with the interfacial properties, rheological properties and the experienced turbulence degree. The correlation between shearing stress and IFT can be quantified if droplet deformation degree vs. droplet orientation angle data is available. When the water cut is close to the inversion point of waxy crude oil emulsion, the interfacial Gibbs free energy change decreased and the shearing energy increased. This feature is also presented in the special regions where

  6. Tension waves in tethered satellite cables

    Science.gov (United States)

    Lallman, F. J.

    1984-01-01

    A one-degree-of-freedom simulation of the Tethered Satellite System (TSS) was programmed using a distributed system model of the tether based on the one-dimensional wave equation. This model represents the time varying tension profile along the tether as the sum of two traveling waves of tension moving in opposite directions. A control loop was devised which combines a deployment rate command with the measured tension at the deployer to produce a smooth, stable rate of deployment of the subsatellite. Simulation results show a buildup of periodic bursts of high frequency oscillation in tension. This report covers the mathematical modelling and simulation results and explains the reason for the observed oscillations. The design of a possible vibration damping device is discussed.

  7. Foundation design for high tension cable guardrails.

    Science.gov (United States)

    2010-06-01

    High tension cable guardrail is becoming increasing popular in median and roadside applications due to the promise of reduced deflections upon impact and reduced maintenance. As the performance of these systems is observed in service, there is a grow...

  8. Modelling Tension Stiffening in Reinforced Concrete Structures

    DEFF Research Database (Denmark)

    Christiansen, Morten Bo; Nielsen, Mogens Peter

    1997-01-01

    Part I of the present thesis deals with crack formation in reinforced concrete and the phenomenon of tension stiffening in concrete tension rods reinforced with deformed bars.Two physical models are presented for uniaxial tension, and they are modified for application on beams subjected to pure...... predicted by the models are compared with experimental data from tests on tension rods as well as flexural beams.In the light of the simple assumptions made and the random nature of cracking, the accordance between the models and the test data is quite good.Part II of the present thesis deals...... flexure.In the first model, the yield zone model, it is assumed that the mean crack distance is a descending function of the reinforcement stress in a crack. Furthermore it is assumed that in certain zones between the cracks the concrete is carrying its full effective tensile strength, i.e. the concrete...

  9. Wetting in flatland: Complex interfacial transitions at inhomogeneous solid-gas interfaces

    Science.gov (United States)

    Yatsyshin, Peter; Duran-Olivencia, Miguel A.; Parry, Andrew O.; Rascon, Carlos; Kalliadasis, Serafim

    Interfaces between the different phases of matter surround us, and since the days of van der Waals have been known to provide key insights into the workings of the atomic world. A classical example of this is the adsorption of liquid films at a planar, homogeneous solid-gas interface. It is well-known that substrates with first-order wetting transitions also exhibit a line of first-order prewetting transitions corresponding to the jump from a thin to a thick adsorbed liquid film. We use classical density functional theory to model adsorption on patterned walls and unravel the zoo of associated interfacial phase transitions and its complexity. We show that the thick prewetting film can nucleate at a lower pressure and to continuously spread out across the surface as the prewetting line is approached, thus manifesting ``complete prewetting in flatland. We also interrogate a planar wall chemically patterned with a deep stripe of a different material. This introduces interfacial unbending from the stripe into the picture. Surprisingly, for thin stripes, the lines of prewetting and unbending may merge, leading to a new two-dimensional wetting transition occurring along the walls. Our results may have ramifications for the design of lab-on-a-chip devices and controlled nanofluidics.

  10. Tension Hydrothorax Related to Disseminated Endometriosis

    Directory of Open Access Journals (Sweden)

    AnnaKate Deal, MD

    2016-01-01

    Full Text Available We present the case of a 34-year-old woman presenting to the emergency department (ED with dyspnea, cough, and fever. She was found to have a tension hydrothorax and was treated with ultrasound-guided thoracentesis in the ED. Subsequent inpatient evaluation showed the patient had disseminated endometriosis. Tension hydrothorax has not been previously described in the literature as a complication of this disease.

  11. Probing Interfacial Water on Nanodiamonds in Colloidal Dispersion.

    Science.gov (United States)

    Petit, Tristan; Yuzawa, Hayato; Nagasaka, Masanari; Yamanoi, Ryoko; Osawa, Eiji; Kosugi, Nobuhiro; Aziz, Emad F

    2015-08-06

    The structure of interfacial water layers around nanoparticles dispersed in an aqueous environment may have a significant impact on their reactivity and on their interaction with biological species. Using transmission soft X-ray absorption spectroscopy in liquid, we demonstrate that the unoccupied electronic states of oxygen atoms from water molecules in aqueous colloidal dispersions of nanodiamonds have a different signature than bulk water. X-ray absorption spectroscopy can thus probe interfacial water molecules in colloidal dispersions. The impacts of nanodiamond surface chemistry and concentration on interfacial water electronic signature are discussed.

  12. Extraction of temperature dependent interfacial resistance of thermoelectric modules

    DEFF Research Database (Denmark)

    Chen, Min

    2011-01-01

    This article discusses an approach for extracting the temperature dependency of the electrical interfacial resistance associated with thermoelectric devices. The method combines a traditional module-level test rig and a nonlinear numerical model of thermoelectricity to minimize measurement errors...... on the interfacial resistance. The extracted results represent useful data to investigating the characteristics of thermoelectric module resistance and comparing performance of various modules.......This article discusses an approach for extracting the temperature dependency of the electrical interfacial resistance associated with thermoelectric devices. The method combines a traditional module-level test rig and a nonlinear numerical model of thermoelectricity to minimize measurement errors...

  13. Density and surface tension of ionic liquids.

    Science.gov (United States)

    Kolbeck, C; Lehmann, J; Lovelock, K R J; Cremer, T; Paape, N; Wasserscheid, P; Fröba, A P; Maier, F; Steinrück, H-P

    2010-12-30

    We measured the density and surface tension of 9 bis[(trifluoromethyl)sulfonyl]imide ([Tf(2)N](-))-based and 12 1-methyl-3-octylimidazolium ([C(8)C(1)Im](+))-based ionic liquids (ILs) with the vibrating tube and the pendant drop method, respectively. This comprehensive set of ILs was chosen to probe the influence of the cations and anions on density and surface tension. When the alkyl chain length in the [C(n)C(1)Im][Tf(2)N] series (n = 1, 2, 4, 6, 8, 10, 12) is increased, a decrease in density is observed. The surface tension initially also decreases but reaches a plateau for alkyl chain lengths greater than n = 8. Functionalizing the alkyl chains with ethylene glycol groups results in a higher density as well as a higher surface tension. For the dependence of density and surface tension on the chemical nature of the anion, relations are only found for subgroups of the studied ILs. Density and surface tension values are discussed with respect to intermolecular interactions and surface composition as determined by angle-resolved X-ray photoelectron spectroscopy (ARXPS). The absence of nonvolatile surface-active contaminants was proven by ARXPS.

  14. Oxygen tension level and human viral infections

    Energy Technology Data Exchange (ETDEWEB)

    Morinet, Frédéric, E-mail: frederic.morinet@sls.aphp.fr [Centre des Innovations Thérapeutiques en Oncologie et Hématologie (CITOH), CHU Saint-Louis, Paris (France); Université Denis Diderot, Sorbonne Paris Cité Paris, Paris (France); Casetti, Luana [Institut Cochin INSERM U1016, Paris (France); François, Jean-Hugues; Capron, Claude [Institut Cochin INSERM U1016, Paris (France); Laboratoire d' Hématologie, Hôpital Ambroise Paré, Boulogne (France); Université de Versailles Saint-Quentin en Yvelynes, Versailles (France); Pillet, Sylvie [Laboratoire de Bactériologie-Virologie-Hygiène, CHU de Saint-Etienne, Saint-Etienne (France); Université de Lyon et Université de Saint-Etienne, Jean Monnet, GIMAP EA3064, F-42023 Saint-Etienne, Lyon (France)

    2013-09-15

    The role of oxygen tension level is a well-known phenomenon that has been studied in oncology and radiotherapy since about 60 years. Oxygen tension may inhibit or stimulate propagation of viruses in vitro as well as in vivo. In turn modulating oxygen metabolism may constitute a novel approach to treat viral infections as an adjuvant therapy. The major transcription factor which regulates oxygen tension level is hypoxia-inducible factor-1 alpha (HIF-1α). Down-regulating the expression of HIF-1α is a possible method in the treatment of chronic viral infection such as human immunodeficiency virus infection, chronic hepatitis B and C viral infections and Kaposi sarcoma in addition to classic chemotherapy. The aim of this review is to supply an updating concerning the influence of oxygen tension level in human viral infections and to evoke possible new therapeutic strategies regarding this environmental condition. - Highlights: • Oxygen tension level regulates viral replication in vitro and possibly in vivo. • Hypoxia-inducible factor 1 (HIF-1α) is the principal factor involved in Oxygen tension level. • HIF-1α upregulates gene expression for example of HIV, JC and Kaposi sarcoma viruses. • In addition to classical chemotherapy inhibition of HIF-1α may constitute a new track to treat human viral infections.

  15. Influence of charged defects on the interfacial bonding strength of tantalum- and silver-doped nanograined TiO2.

    Science.gov (United States)

    Azadmanjiri, Jalal; Wang, James; Berndt, Christopher C; Kapoor, Ajay; Zhu, De Ming; Ang, Andrew S M; Srivastava, Vijay K

    2017-05-17

    A nano-grained layer including line defects was formed on the surface of a Ti alloy (Ti alloy , Ti-6Al-4V ELI). Then, the micro- and nano-grained Ti alloy with the formation of TiO 2 on its top surface was coated with a bioactive Ta layer with or without incorporating an antibacterial agent of Ag that was manufactured by magnetron sputtering. Subsequently, the influence of the charged defects (the defects that can be electrically charged on the surface) on the interfacial bonding strength and hardness of the surface system was studied via an electronic model. Thereby, material systems of (i) Ta coated micro-grained titanium alloy (Ta/MGTi alloy ), (ii) Ta coated nano-grained titanium alloy (Ta/NGTi alloy ), (iii) TaAg coated micro-grained titanium alloy (TaAg/MGTi alloy ) and (iv) TaAg coated nano-grained titanium alloy (TaAg/NGTi alloy ) were formed. X-ray photoelectron spectroscopy was used to probe the electronic structure of the micro- and nano-grained Ti alloy , and so-formed heterostructures. The thin film/substrate interfaces exhibited different satellite peak intensities. The satellite peak intensity may be related to the interfacial bonding strength and hardness of the surface system. The interfacial layer of TaAg/NGTi alloy exhibited the highest satellite intensity and maximum hardness value. The increased bonding strength and hardness in the TaAg/NGTi alloy arises due to the negative core charge of the dislocations and neighbor space charge accumulation, as well as electron accumulation in the created semiconductor phases of larger band gap at the interfacial layer. These two factors generate interfacial polarization and enhance the satellite intensity. Consequently, the interfacial bonding strength and hardness of the surface system are improved by the formation of mixed covalent-ionic bonding structures around the dislocation core area and the interfacial layer. The bonding strength relationship by in situ XPS on the metal/TiO 2 interfacial layer may

  16. Tensile mechanical behavior of hollow and filled carbon nanotubes under tension or combined tension-torsion

    Science.gov (United States)

    Jeong, Byeong-Woo; Lim, Jang-Keun; Sinnott, Susan B.

    2007-01-01

    The tensile mechanical behavior of hollow and filled single-walled carbon nanotubes under tension or combined tension-torsion is examined using classical molecular dynamics simulations. These simulations indicate that the tensile strength under combined tension-torsion can be increased by filling the carbon nanotubes, and the amount of this increase depends on the kind of filling material. They also predict that the tensile strength under combined tension-torsion decreases linearly under applied torsion. The tensile strength can be modified by adjusting the system temperature and through chemical functionalization to the carbon nanotube walls.

  17. Soil tension mediates isotope fractionation during soil water evaporation

    Science.gov (United States)

    Gaj, Marcel; McDonnell, Jeffrey

    2017-04-01

    Isotope tracing of the water cycle is increasing in its use and usefulness. Many new studies are extracting soil waters and relating these to streamflow, groundwater recharge and plant transpiration. Nevertheless, unlike isotope fractionation factors from open water bodies, soil water fractionation factors are poorly understood and until now, only empirically derived. In contrast to open water evaporation where temperature, humidity and vapor pressure gradient define fractionation (as codified in the well-known Craig and Gordon model), soil water evaporation includes additionally, fractionation by matrix effects. There is yet no physical explanation of kinetic and equilibrium fraction from soil water within the soil profile. Here we present a simple laboratory experiment with four admixtures of soil grain size (from sand to silt to clay). Oven-dried samples were spiked with water of known isotopic composition at different soil water contents. Soils were then stored in sealed bags and the headspace filled with dry air and allowed to equilibrate for 24hours. Isotopic analysis of the headspace vapor was done with a Los Gatos Inc. water vapor isotope analyzer. Soil water potential of subsamples were measured with a water potential meter. We show for the first time that soil tension controls isotope fractionation in the resident soil water. Below a Pf 3.5 the δ-values of 18O and 2H of the headspace vapor is more positive and increases with increasing soil water potential. Surprisingly, we find that the relationship between soil tension and equilibrium fractionation is independent of soil type. However, δ-values of each soil type plot along a distinct evaporation line. These results indicate that equilibrium fractionation is affected by soil tension in addition to temperature. Therefore, at high soil water tension (under dry conditions) equilibrium fractionation is not consistent with current empirical formulations that ignore these effects. These findings may have

  18. Synthesis of exfoliated PA66 nanocomposites via interfacial ...

    Indian Academy of Sciences (India)

    Addition of nanoparticles decreases n first, then n increases with nanoparticle content. Keywords. Polyamide 66; nanocomposite; interfacial polymerization; nanoparticle; crystallization. 1. Introduction. Polyamides (PA) are polymers containing amide links. Nylon is a general name for synthetic polyamides. Polyamides were.

  19. Charles J. McMahon Interfacial Segregation and Embrittlement Symposium

    National Research Council Canada - National Science Library

    Vitek, Vaclav

    2003-01-01

    .... McMahon Interfacial Segregation and Embrittlement Symposium: Grain Boundary Segregation and Fracture in Steels was sponsored by ASM International, Materials Science Critical Technology Sector, Structural Materials Division, Materials Processing...

  20. Final Project Report for "Interfacial Thermal Resistance of Carbon Nanotubes”

    Energy Technology Data Exchange (ETDEWEB)

    Cumings, John [Univ. of Maryland, College Park, MD (United States)

    2016-04-15

    This report describes an ongoing project to comprehensively study the interfacial thermal boundary resistance (Kapitza resistance) of carbon nanotubes. It includes a list of publications, personnel supported, the overall approach, accomplishments and future plans.

  1. Interfacial Thermal Transport via One-Dimensional Atomic Junction Model

    Directory of Open Access Journals (Sweden)

    Guohuan Xiong

    2018-03-01

    Full Text Available In modern information technology, as integration density increases rapidly and the dimension of materials reduces to nanoscale, interfacial thermal transport (ITT has attracted widespread attention of scientists. This review introduces the latest theoretical development in ITT through one-dimensional (1D atomic junction model to address the thermal transport across an interface. With full consideration of the atomic structures in interfaces, people can apply the 1D atomic junction model to investigate many properties of ITT, such as interfacial (Kapitza resistance, nonlinear interface, interfacial rectification, and phonon interference, and so on. For the ballistic ITT, both the scattering boundary method (SBM and the non-equilibrium Green’s function (NEGF method can be applied, which are exact since atomic details of actual interfaces are considered. For interfacial coupling case, explicit analytical expression of transmission coefficient can be obtained and it is found that the thermal conductance maximizes at certain interfacial coupling (harmonic mean of the spring constants of the two leads and the transmission coefficient is not a monotonic decreasing function of phonon frequency. With nonlinear interaction—phonon–phonon interaction or electron–phonon interaction at interface, the NEGF method provides an efficient way to study the ITT. It is found that at weak linear interfacial coupling, the nonlinearity can improve the ITT, but it depresses the ITT in the case of strong-linear coupling. In addition, the nonlinear interfacial coupling can induce thermal rectification effect. For interfacial materials case which can be simulated by a two-junction atomic chain, phonons show interference effect, and an optimized thermal coupler can be obtained by tuning its spring constant and atomic mass.

  2. Hyper-cross-linked, hybrid membranes via interfacial polymerization

    OpenAIRE

    Raaijmakers, Michiel

    2015-01-01

    Hyper-cross-linked, hybrid membranes consist of covalent networks of alternating organic and inorganic, or biological groups. This thesis reports on the preparation of such hybrid networks via interfacial polymerization. The structure-property relationships of the hybrid networks depend strongly on the type, size and flexibility of the constituents. The collection of polymers that can be synthesized via interfacial polymerization includes polyamides, polyurethanes, polyureas, polyanilines, po...

  3. Interfacial nanoarchitectonics for solid-state lithium batteries.

    Science.gov (United States)

    Takada, Kazunori

    2013-06-18

    Strong demand for solid-state lithium batteries has prompted intensive research for achieving fast ionic conduction in solids. Although the highest conductivity found among sulfides is higher than that of liquid electrolytes, it improves the battery performance only in combination with electrodes via a low-resistance interface. This Article reviews some interfacial structures that lower the interfacial resistance to enable high-power interfaces by controlling the carrier density.

  4. Modeling interfacial liquid layers on environmental ices

    Directory of Open Access Journals (Sweden)

    M. H. Kuo

    2011-09-01

    Full Text Available Interfacial layers on ice significantly influence air-ice chemical interactions. In solute-containing aqueous systems, a liquid brine may form upon freezing due to the exclusion of impurities from the ice crystal lattice coupled with freezing point depression in the concentrated brine. The brine may be segregated to the air-ice interface where it creates a surface layer, in micropockets, or at grain boundaries or triple junctions.

    We present a model for brines and their associated liquid layers in environmental ice systems that is valid over a wide range of temperatures and solute concentrations. The model is derived from fundamental equlibrium thermodynamics and takes into account nonideal solution behavior in the brine, partitioning of the solute into the ice matrix, and equilibration between the brine and the gas phase for volatile solutes. We find that these phenomena are important to consider when modeling brines in environmental ices, especially at low temperatures. We demonstrate its application for environmentally important volatile and nonvolatile solutes including NaCl, HCl, and HNO3. The model is compared to existing models and experimental data from literature where available. We also identify environmentally relevant regimes where brine is not predicted to exist, but the QLL may significantly impact air-ice chemical interactions. This model can be used to improve the representation of air-ice chemical interactions in polar atmospheric chemistry models.

  5. Quantum interference in an interfacial superconductor.

    Science.gov (United States)

    Goswami, Srijit; Mulazimoglu, Emre; Monteiro, Ana M R V L; Wölbing, Roman; Koelle, Dieter; Kleiner, Reinhold; Blanter, Ya M; Vandersypen, Lieven M K; Caviglia, Andrea D

    2016-10-01

    The two-dimensional superconductor that forms at the interface between the complex oxides lanthanum aluminate (LAO) and strontium titanate (STO) has several intriguing properties that set it apart from conventional superconductors. Most notably, an electric field can be used to tune its critical temperature (T c ; ref. 7), revealing a dome-shaped phase diagram reminiscent of high-T c superconductors. So far, experiments with oxide interfaces have measured quantities that probe only the magnitude of the superconducting order parameter and are not sensitive to its phase. Here, we perform phase-sensitive measurements by realizing the first superconducting quantum interference devices (SQUIDs) at the LAO/STO interface. Furthermore, we develop a new paradigm for the creation of superconducting circuit elements, where local gates enable the in situ creation and control of Josephson junctions. These gate-defined SQUIDs are unique in that the entire device is made from a single superconductor with purely electrostatic interfaces between the superconducting reservoir and the weak link. We complement our experiments with numerical simulations and show that the low superfluid density of this interfacial superconductor results in a large, gate-controllable kinetic inductance of the SQUID. Our observation of robust quantum interference opens up a new pathway to understanding the nature of superconductivity at oxide interfaces.

  6. Biomimetic Interfacial Electron-Induced Electrochemiluminesence.

    Science.gov (United States)

    Pu, Guiqiang; Zhang, Dongxu; Mao, Xiang; Zhang, Zhen; Wang, Huan; Ning, Xingming; Lu, Xiaoquan

    2018-04-17

    We provide here, for the first time, a new interfacial electron-induced electrochemiluminescence (IEIECL) system, realizing bionic construction of bioluminescence (BL) by exploiting electrochemiluminescence (ECL) and ITIES (the interface between two immiscible electrolyte solutions). Significantly, the superiority of the IEIECL system is embodied with the solution of the two bottlenecks encountered in the conventional ECL innovation: that are (a) the applications of hydrophobic luminophores in more commonly used aqueous solution are inhibited tremendously due to the poor inherent solubility and the instability of radicals and (b) the analytes, insoluble in water, are hard to be discovered in an aqueous system because of too little content. More productive IEIECL radiation, analogous to BL, originates from the triplet excited state porphyrin in comparison to the homogeneous ECL. The mechanism of IEIECL, as well as the interaction mechanism between IEIECL and charge transfer (comprising electron transfer (ET), ion transfer (IT), and facilitated ion transfer (FIT)) at the ITIES, are explored in detail. Finally, we emphasize the actual application potential of the IEIECL system with the detection of cytochrome c (Cyt c); it is a key biomolecule in the electron transport chain in the process of biological oxidation and is also an intermediate species in apoptosis. Potentially, the IEIECL system permits ones to explore the lifetime and diffusion path of free radicals, as well as imparting a possibility for the construction of a bionic sensor.

  7. Droplet-based interfacial capacitive sensing.

    Science.gov (United States)

    Nie, Baoqing; Xing, Siyuan; Brandt, James D; Pan, Tingrui

    2012-03-21

    This paper presented a novel droplet-based pressure sensor using elastic and capacitive electrode-electrolyte interfaces to achieve ultrahigh mechanical-to-electrical sensitivity (1.58 μF kPa(-1)) and resolution (1.8 Pa) with a simple device architecture. The miniature transparent droplet sensors, fabricated by one-step laser micromachining, consisted of two flexible polymer membranes with conductive coating and a separation layer hosting a sensing chamber for an electrolyte droplet. The sensing principle primarily relied on high elasticity of the sensing droplet and large capacitance presented at the electrode-electrolyte interface. A simple surface modification scheme was introduced to the conductive coating, which reduced hysteresis of the droplet deformation without substantially compromising the interfacial capacitance. Moreover, the major concern of liquid evaporation was addressed by a mixture of glycerol and electrolyte with long-term stability in a laboratory environment. Theoretical analyses and experimental investigations on several design parameters (i.e., the dimensions of the sensing chamber and the droplet size) were thoroughly conducted to characterize and optimize the overall sensitivity of the device. Moreover, the environmental influences (e.g., temperature and humidity) on the capacitive measurement were further investigated. Finally, the simply constructed and mechanically flexible droplet sensor was successfully applied to detect minute blood pressure variations on the skin surface (with the maximum value less than 100 Pa) throughout cardiovascular cycles.

  8. Interfacial coupling in multiferroic/ferromagnet heterostructures

    Science.gov (United States)

    Trassin, M.; Clarkson, J. D.; Bowden, S. R.; Liu, Jian; Heron, J. T.; Paull, R. J.; Arenholz, E.; Pierce, D. T.; Unguris, J.

    2013-04-01

    We report local probe investigations of the magnetic interaction between BiFeO3 films and a ferromagnetic Co0.9Fe0.1 layer. Within the constraints of intralayer exchange coupling in the Co0.9Fe0.1, the multiferroic imprint in the ferromagnet results in a collinear arrangement of the local magnetization and the in-plane BiFeO3 ferroelectric polarization. The magnetic anisotropy is uniaxial, and an in-plane effective coupling field of order 10 mT is derived. Measurements as a function of multiferroic layer thickness show that the influence of the multiferroic layer on the magnetic layer becomes negligible for 3 nm thick BiFeO3 films. We ascribe this breakdown in the exchange coupling to a weakening of the antiferromagnetic order in the ultrathin BiFeO3 film based on our x-ray linear dichroism measurements. These observations are consistent with an interfacial exchange coupling between the CoFe moments and a canted antiferromagnetic moment in the BiFeO3.

  9. Flow in porous media, phase behavior and ultralow interfacial tensions: mechanisms of enhanced petroleum recovery. Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Davis, H.T.; Scriven, L.E.

    1982-01-01

    A major program of university research, longer-ranged and more fundamental in approach than industrial research, into basic mechanisms of enhancing petroleum recovery and into underlying physics, chemistry, geology, applied mathematics, computation, and engineering science has been built at Minnesota. The 1982 outputs of the interdisciplinary team of investigators were again ideas, instruments, techniques, data, understanding and skilled people: forty-one scientific and engineering papers in leading journals; four pioneering Ph.D. theses; numerous presentations to scientific and technical meetings, and to industrial, governmental and university laboratories; vigorous program of research visits to and from Minnesota; and two outstanding Ph.D.'s to research positions in the petroleum industry, one to a university faculty position, one to research leadership in a governmental institute. This report summarizes the 1982 papers and theses and features sixteen major accomplishments of the program during that year. Abstracts of all forty-five publications in the permanent literature are appended. Further details of information transfer and personnel exchange with industrial, governmental and university laboratories appear in 1982 Quarterly Reports available from the Department of Energy and are not reproduced here. The Minnesota program continues in 1983, notwithstanding earlier uncertainty about the DOE funding which finally materialized and is the bulk of support. Supplemental grants-in-aid from nine companies in the petroleum industry are important, as are the limited University and departmental contributions. 839 references, 172 figures, 29 tables.

  10. Interfacial Tension and Contact Angle Determination in Water-sandstone Systems with Injection of Flue Gas and CO2

    NARCIS (Netherlands)

    Shojaikaveh, N.; Rudolph, E.S.J.; Rossen, W.R.; Van Hemert, P.; Wolf, K.H.A.A.

    2013-01-01

    Carbon capture and storage (CCS) has the potential for reducing CO2 emissions to the atmosphere. This option includes storage strategies such as CO2 injection into deep saline aquifers, depleted oil and gas reservoirs, and unmineable coal seams. This process is largely controlled by the interactions

  11. DETERMINING THE EFFECTIVE INTERFACIAL TENSION OF DNAPL FINGERING IN WATER-SATURATED POROUS MEDIA USING FRACTAL CONCEPTS. (R826157)

    Science.gov (United States)

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  12. Role of Interfacial Tensions in the Translocation of Rhodococcus erythropolis during Growth in a Two Phase Culture

    NARCIS (Netherlands)

    Iwabuchi, Noriyuki; Sharma, Prashant K.; Sunairi, Michio; Kishi, Emi; Sugita, Kazushige; van der Mei, Henny C.; Nakajima, Mutsuyasu; Busscher, Henk J.

    2009-01-01

    Rhodococcus erythropolis PR4 is an alkane-degrading bacterium, which grows well in media containing high concentrations of alkanes. These properties give the organism potential in the bioremediation of various environments contaminated by alkanes. In this study, we report the translocation of R.

  13. Salinity of injection water and its impact on oil recovery absolute permeability, residual oil saturation, interfacial tension and capillary pressure

    Directory of Open Access Journals (Sweden)

    Mehdi Mohammad Salehi

    2017-06-01

    This paper presents laboratory investigation of the effect of salinity injection water on oil recovery, pressure drop, permeability, IFT and relative permeability in water flooding process. The experiments were conducted at the 80 °C and a net overburden pressure of 1700 psi using core sample. The results of this study have been shown oil recovery increases as the injected water salinity up to 200,000 ppm and appointment optimum salinity. This increase has been found to be supported by a decrease in the IFT. This effect caused a reduction in capillary pressure increasing the tendency to reduce the residual oil saturation.

  14. Limited Agreement between the Interfacial Tension and Differential Capacity Data for the Polarised Water|1,2-dichloroethane Interface

    Czech Academy of Sciences Publication Activity Database

    Trojánek, Antonín; Lhotský, Alexandr; Mareček, Vladimír; Samec, Zdeněk

    2004-01-01

    Roč. 565, 1/2 (2004), s. 243-250 ISSN 0022-0728 R&D Projects: GA MŠk ME 502 Institutional research plan: CEZ:AV0Z4040901 Keywords : quasi-elastic laser light scattering * immiscible electrolyte solutions * differential capacity Subject RIV: CG - Electrochemistry Impact factor: 2.228, year: 2004

  15. Topological fluid dynamics of interfacial flows

    DEFF Research Database (Denmark)

    Brøns, Morten

    1994-01-01

    The topological description of flows in the vicinity of a solid boundary, that is familiar from the aerodynamics literature, has recently been extended to the case of flow at a liquid–gas interface or a free surface by Lugt [Phys. Fluids 30, 3647 (1987)]. Lugt's work is revisited in a more general...... setting, including nonconstant curvature of the interface and gradients of surface tension, using tools of modern nonlinear dynamics. Bifurcations of the flow pattern occur at degenerate configurations. Using the theory of unfolding, this paper gives a complete description of the bifurcations that depend...... on terms up to the second order. The general theory of this paper is applied to the topology of streamlines during the breaking of a wave and to the flow below a stagnant surface film. Physics of Fluids is copyrighted by The American Institute of Physics....

  16. Quantitative analysis of liquid penetration kinetics and slaking of aggregates as related to solid-liquid interfacial properties

    Science.gov (United States)

    Goebel, Marc-O.; Woche, Susanne K.; Bachmann, Jörg

    2012-06-01

    SummaryAggregate stability is frequently shown to be enhanced by strong soil water repellency, however, there is limited systematic evidence on this effect for moderately (subcritically) water repellent soils. This study aimed to investigate the specific effects of interfacial properties on the liquid penetration kinetics in relation to the stability of subcritically water repellent aggregates (4-6.3 mm) from various arable and forest soils against breakdown by slaking. In contrast to many other studies, where aggregate stability was determined by wet sieving, we here assessed the stability by immersion of air-dry aggregates in water-ethanol solutions with surface tensions ranging from 30 to 70 mN m-1. This approach allowed a highly sensitive discrimination of different stability levels and the determination of breakdown kinetics also for less stable aggregates. Interfacial properties were characterized in terms of contact angle measured on crushed aggregates, θc, and calculated for intact aggregates, θi, based on infiltration measurements with water and ethanol. Aggregate stability turned out to be higher in forest soils compared to arable soils with topsoil aggregates generally found to be more stable than subsoil aggregates. For water repellent aggregates, characterized by contact angles >40° and low water infiltration rates (0.25 mm3 s-0.5) more than 80% of the aggregates were disrupted. In accordance, we found a close relationship between aggregate stability and wettability with differences between θc and θi being generally small. In addition, aggregate stability turned out to be related to organic carbon content. However, correlation analysis revealed that both persistence of aggregate stability and kinetics of aggregate breakdown were more strongly affected by the contact angle, θc (r = 0.90 and r = -0.83, respectively) and θi (r = 0.89 and r = -0.76, respectively) than the organic carbon content (r = 0.62 and -0.52, respectively), suggesting that

  17. Preparation of microspheres and microcapsules by interfacial polycondensation techniques.

    Science.gov (United States)

    Arshady, R

    1989-01-01

    A methodological review of the production of microspheres/microcapsules by interfacial polycondensation is presented and the mechanisms of particle and capsule formation are discussed. Procedures for interfacial polycondensation employed for the preparation of microspheres/microcapsules involve the polycondensation of two complementary monomers in a two phase suspension system. Each of the two complementary monomers resides largely in one of the two immiscible phases in the suspension system. The resulting polycondensate, which is formed at or on one side of the interface, may, or may not, be soluble in the droplet phase. If the polymer is soluble in the droplets, particulate microspheres or monolithic microcapsules are formed, i.e. particle forming interfacial polycondensation. If the polymer is insoluble in the droplets, it forms a membrane around them, and the droplets are thus individually encapsulated by the polymer. This leads to the formation of capsular microspheres or reservoir microcapsules, and hence capsule forming interfacial polycondensation. A major example of particle forming interfacial polycondensation is that of phosgene with bisphenol A recently developed for the production of polycarbonate resins in particle form. Capsule forming interfacial polycondensation is widely used to prepare polyamide (nylon) microcapsules containing proteins, pharmaceuticals, etc.

  18. Modeling of a Curvilinear Planar Crack with a Curvature-Dependent Surface Tension

    KAUST Repository

    Zemlyanova, A. Y.

    2012-01-01

    An approach to modeling fracture incorporating interfacial mechanics is applied to the example of a curvilinear plane strain crack. The classical Neumann boundary condition is augmented with curvature-dependent surface tension. It is shown that the considered model eliminates the integrable crack-tip stress and strain singularities of order 1/2 present in the classical linear fracture mechanics solutions, and also leads to the sharp crack opening that is consistent with empirical observations. Unlike for the case of a straight crack, for a general curvilinear crack some components of the stresses and the derivatives of the displacements may still possess weaker singularities of a logarithmic type. Generalizations of the present study that lead to complete removal of all crack-tip singularities, including logarithmic, are the subject of a future paper. © 2012 Society for Industrial and Applied Mathematics.

  19. Surface tension and wetting behaviour of Bi-In-Sn alloys

    International Nuclear Information System (INIS)

    Ervina Efzan Mohd Noor; Ahmad Badri Ismail; Soong, T.K.; Chin, Y.T.; Luay Bakir Hussain

    2007-01-01

    Concerns about possible landfill contamination, influent discharge from production process are one of the reasons convert from lead-containing electronics to lead-free containing. The surface and interfacial properties of Bi-In-Sn lead-free solder system as a basic system of multicomponent alloys proposed as lead-free solder materials have been studied. The surface tension of Bi-In-Sn lead-free solder system of melting temperature 60 degree Celsius has been measured the temperature range 80 degree Celsius and 140 degree Celsius. The study of the wetting behaviour of Bi-In-Sn lead-free solder system on a Cu substrate has been performed by measuring contact angle on various metal substrates by Optical Microscopy with software. (author)

  20. Tension Distribution in a Tendon-Driven Robotic Finger

    Science.gov (United States)

    Abdallah, Muhammad E. (Inventor); Platt, Robert (Inventor); Wampler, II, Charles W. (Inventor)

    2013-01-01

    A method is provided for distributing tension among tendons of a tendon-driven finger in a robotic system, wherein the finger characterized by n degrees of freedom and n+1 tendons. The method includes determining a maximum functional tension and a minimum functional tension of each tendon of the finger, and then using a controller to distribute tension among the tendons, such that each tendon is assigned a tension value less than the maximum functional tension and greater than or equal to the minimum functional tension. The method satisfies the minimum functional tension while minimizing the internal tension in the robotic system, and satisfies the maximum functional tension without introducing a coupled disturbance to the joint torques. A robotic system includes a robot having at least one tendon-driven finger characterized by n degrees of freedom and n+1 tendons, and a controller having an algorithm for controlling the tendons as set forth above.

  1. Capillary meniscus dynamometry—method for determining the surface tension of drops and bubbles with isotropic and anisotropic surface stress distributions.

    Science.gov (United States)

    Danov, Krassimir D; Stanimirova, Rumyana D; Kralchevsky, Peter A; Marinova, Krastanka G; Alexandrov, Nikola A; Stoyanov, Simeon D; Blijdenstein, Theodorus B J; Pelan, Eddie G

    2015-02-15

    The stresses acting in interfacial adsorption layers with surface shear elasticity are, in general, anisotropic and non-uniform. If a pendant drop or buoyant bubble is covered with such elastic layer, the components of surface tension acting along the "meridians" and "parallels", σ(s) and σ(φ), can be different and, then, the conventional drop shape analysis (DSA) is inapplicable. Here, a method for determining σ(s) and σ(φ) is developed for axisymmetric menisci. This method, called 'capillary meniscus dynamometry' (CMD), is based on processing data for the digitized drop/bubble profile and capillary pressure. The principle of the CMD procedure for data processing is essentially different from that of DSA. Applying the tangential and normal surface stress balance equations, σ(s) and σ(φ) are determined in each interfacial point without using any rheological model. The computational procedure is fast and could be used in real time, during a given process. The method is applied to determine σ(s) and σ(φ) for bubbles and drops formed on the tip of a capillary immersed in solutions of the protein HFBII hydrophobin. Upon a surface compression, meridional wrinkles appear on the bubble surface below the bubble "equator", where the azimuthal tension σ(φ) takes negative values. The CMD method allows one to determine the local tensions acting in anisotropic interfacial layers (films, membranes), like those formed from proteins, polymers, asphaltenes and phospholipids. The CMD is applicable also to fluid interfaces (e.g. surfactant solutions), for which it gives the same surface tension as the conventional methods. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. TBK1 duplication is found in normal tension and not in high tension ...

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Genetics; Volume 95; Issue 2. TBK1 duplication is found in normal tension and not in high tension glaucoma patients of Indian origin. LALIT KAURANI MANSI VISHAL JHARNA RAY ABHIJIT SEN KUNAL RAY ARIJIT MUKHOPADHYAY. RESEARCH NOTE Volume 95 Issue 2 June 2016 pp 459- ...

  3. TBK1 duplication is found in normal tension and not in high tension ...

    Indian Academy of Sciences (India)

    Supplementary data: TBK1 duplication is found in normal tension and not in high tension glaucoma patients of Indian origin. Lalit Kaurani, Mansi Vishal, Jharna Ray, Abhijit Sen, Kunal Ray and Arijit Mukhopadhyay. J. Genet. 95, 459–461. Table 1. Intraocular pressure of NTG and HTG patients. Total. Mean IOP. Mean IOP ...

  4. Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume I. Chapters 1-5)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, T.; Park, J.; Kojasoy, G.

    2003-03-15

    Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.

  5. Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume III. Chapters 11-14)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, T.; Park, J.; Kojasoy, G.

    2003-03-15

    Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.

  6. Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume IV. Chapters 15-19)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, T.; Park, J.; Kojasoy, G.

    2003-03-15

    Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.

  7. Interfacial Area and Interfacial Transfer in Two-Phase Flow Systems (Volume II. Chapters 6-10)

    Energy Technology Data Exchange (ETDEWEB)

    Guo, T.; Park, J.; Kojasoy, G.

    2003-03-15

    Experiments were performed on horizontal air-water bubbly two-phase flow, axial flow, stratified wavy flow, and annular flow. Theoretical studies were also undertaken on interfacial parameters for a horizontal two-phase flow.

  8. Percutaneous tension band wiring for patellar fractures.

    Science.gov (United States)

    Rathi, Akhilesh; Swamy, M K S; Prasantha, I; Consul, Ashu; Bansal, Abhishek; Bahl, Vibhu

    2012-08-01

    To evaluate outcome of percutaneous tension band wiring for transverse fractures of the patella. 16 men and 7 women aged 27 to 65 (mean, 40) years underwent percutaneous tension band wiring for transverse fractures of the patella with a displacement of >3 mm. Pain, operating time, mobility, functional score, and complications were evaluated. 20 patients underwent successful percutaneous tension band wiring. The remaining 3 patients in whom closed reduction failed underwent open reduction and tension band wiring. The mean operating time was 46 (range, 28-62) minutes. The mean follow-up period was 20 (range, 15-30) months. At the latest follow-up, all patients had regained full extension. The objective score was excellent in 20 patients and good in 3, whereas the subjective score was excellent in 17, good in 5, and fair in one. All patients had radiological union at week 8. One patient had patellofemoral arthritis (secondary to a postoperative articular step). Two patients developed superficial infections, which resolved after antibiotic therapy. Mean thigh muscle wasting was 0.7 (range, 0.4-1) cm. Three patients encountered hardware problems (impingement/irritation of the skin over the knee) necessitating implant removal. Percutaneous tension band wiring is a viable option for transverse fractures of the patella.

  9. On relation between the quark-gluon bag surface tension and the colour tube string tension

    International Nuclear Information System (INIS)

    Bugaev, K.A.; Zinovjev, G.M.

    2010-01-01

    We revisit the bag phenomenology of deconfining phase transition aiming to replenish it by introducing systematically the bag surface tension. Comparing the free energies of such bags and the strings confining the static quark-antiquark pair, we express the string tension in terms of the bag surface tension and the bulk pressure in order to estimate the bag characteristics using the lattice QCD (LQCD) data. Our analysis of the bag entropy density demonstrates that the surface tension coefficient is amazingly negative at the cross-over (continuous transition). The approach developed allows us to naturally account for an origin of a pronounced maximum (observed in the LQCD studies) in the behaviour of heavy quark-antiquark pair entropy. The vicinity of the (tri-)critical endpoint is also analyzed to clarify the meaning of vanishing surface tension coefficient.

  10. Chemical responses to modified lignin composition in tension wood of hybrid poplar (Populus tremula x Populus alba).

    Science.gov (United States)

    Al-Haddad, Jameel M; Kang, Kyu-Young; Mansfield, Shawn D; Telewski, Frank W

    2013-04-01

    The effect of altering the expression level of the F5H gene was investigated in three wood tissues (normal, opposite and tension wood) in 1-year-old hybrid poplar clone 717 (Populus tremula × Populus alba L.), containing the F5H gene under the control of the C4H promoter. Elevated expression of the F5H gene in poplar has been previously reported to increase the percent syringyl content of lignin. The wild-type and three transgenic lines were inclined 45° for 3 months to induce tension wood formation. Tension and opposite wood from inclined trees, along with normal wood from control trees, were analyzed separately for carbohydrates, lignin, cellulose crystallinity and microfibril angle (MFA). In the wild-type poplar, the lignin in tension wood contained a significantly higher percentage of syringyl than normal wood or opposite wood. However, there was no significant difference in the percent syringyl content of the three wood types within each of the transgenic lines. Increasing the F5H gene expression caused an increase in the percent syringyl content and a slight decrease in the total lignin in normal wood. In tension wood, the addition of a gelatinous layer in the fiber walls resulted in a consistently lower percentage of total lignin in the tissue. Acid-soluble lignin was observed to increase by up to 2.3-fold in the transgenic lines. Compared with normal wood and opposite wood, cell wall crystallinity in tension wood was higher and the MFA was smaller, as expected, with no evidence of an effect from modifying the syringyl monomer ratio. Tension wood in all the lines contained consistently higher total sugar and glucose percentages when compared with normal wood within the respective lines. However, both sugar and glucose percentages were lower in the tension wood of transgenic lines when compared with the tension wood of wild-type trees. Evaluating the response of trees with altered syringyl content to gravity will improve our understanding of the changes

  11. Removing adsorbed heavy metal ions from sand surfaces via applying interfacial properties of rhamnolipid.

    Science.gov (United States)

    Haryanto, Bode; Chang, Chien-Hsiang

    2015-01-01

    In this study, the interfacial properties of biosurfactant rhamnolipid were investigated and were applied to remove adsorbed heavy metal ions from sand surfaces with flushing operations. The surface tension-lowering activity, micelle charge characteristic, and foaming ability of rhamnolipid were identified first. For rhamnolipid in water, the negatively charged characteristic of micelles or aggregates was confirmed and the foaming ability at concentrations higher than 40 mg/L was evaluated. By using the rhamnolipid solutions in a batch washing approach, the potential of applying the interfacial properties of rhamnolipid to remove adsorbed copper ions from sand surfaces was then demonstrated. In rhamnolipid solution flushing operations for sand-packed medium, higher efficiency was found for the removal of adsorbed copper ions with residual type than with inner-sphere interaction type, implying the important role of interaction type between the copper ion and the sand surface in the removal efficiency. In addition, the channeling effect of rhamnolipid solution flow in the sand-packed medium was clearly observed in the solution flushing operations and was responsible for the low removal efficiency with low contact areas between solution and sand. By using rhamnolipid solution with foam to flush the sand-packed medium, one could find that the channeling effect of the solution flow was reduced and became less pronounced with the increase in the rhamnolipid concentration, or with the enhanced foaming ability. With the reduced channeling effect in the flushing operations, the removal efficiency for adsorbed copper ions was significantly improved. The results suggested that the foam-enhanced rhamnolipid solution flushing operation was efficient in terms of surfactant usage and operation time.

  12. On the interfacial fracture of porcelain/zirconia and graded zirconia dental structures

    Science.gov (United States)

    Chai, Herzl; Lee, James J.-W; Mieleszko, Adam J.; Chu, Stephen J.; Zhang, Yu

    2014-01-01

    Porcelain fused to zirconia (PFZ) restorations are widely used in prosthetic dentistry. However, their susceptibility to fracture remains a practical problem. The failure of PFZ prostheses often involves crack initiation and growth in the porcelain, which may be followed by fracture along the porcelain/zirconia (P/Z) interface. In this work, we characterized the process of fracture in two PFZ systems, as well as a newly developed graded glass-zirconia structure with emphases placed on resistance to interfacial cracking. Thin porcelain layers were fused onto Y-TZP plates with or without the presence of a glass binder. The specimens were loaded in a four-point-bend fixture with the thin porcelain veneer in tension, simulating the lower portion of the connectors and marginal areas of a fixed dental prosthesis (FDP) during occlusal loading. The evolution of damage was observed by a video camera. The fracture was characterized by unstable growth of cracks perpendicular to the P/Z interface (channel cracks) in the porcelain layer, which was followed by stable cracking along the P/Z interface. The interfacial fracture energy GC was determined by a FEA taking into account stress shielding effects due to the presence of adjacent channel cracks. The resulting GC was well less than commonly reported values for similar systems. Fracture in the graded Y-TZP samples occurred by a single channel crack at a much greater stress than for PFZ. No delamination between the residual glass layer and graded zirconia occurred in any of the tests. Combined with its enhanced resistance to edge chipping and good esthetic quality, graded Y-TZP emerges as a viable material concept for dental restorations. PMID:24769152

  13. Tension Stiffened and Tendon Actuated Manipulator

    Science.gov (United States)

    Doggett, William R. (Inventor); Dorsey, John T. (Inventor); Ganoe, George G. (Inventor); King, Bruce D. (Inventor); Jones, Thomas C. (Inventor); Mercer, Charles D. (Inventor); Corbin, Cole K. (Inventor)

    2015-01-01

    A tension stiffened and tendon actuated manipulator is provided performing robotic-like movements when acquiring a payload. The manipulator design can be adapted for use in-space, lunar or other planetary installations as it is readily configurable for acquiring and precisely manipulating a payload in both a zero-g environment and in an environment with a gravity field. The manipulator includes a plurality of link arms, a hinge connecting adjacent link arms together to allow the adjacent link arms to rotate relative to each other and a cable actuation and tensioning system provided between adjacent link arms. The cable actuation and tensioning system includes a spreader arm and a plurality of driven and non-driven elements attached to the link arms and the spreader arm. At least one cable is routed around the driven and non-driven elements for actuating the hinge.

  14. Tensions between Teams and Their Leaders

    Directory of Open Access Journals (Sweden)

    J. David Johnson

    2016-10-01

    Full Text Available The intersection of teamwork and leadership results in tensions, dilemmas, and paradoxes for both individuals and for institutions such as simultaneously empowering individuals at the same time it frustrates them when our naive, cultural understanding of leadership centralizes power and values leaders who can impose their will and vision on others. Perhaps the fundamental paradox of teamwork and leadership is that the more leadership is focused on an individual the less likely a team’s potential will be realized. Six specific domains where tensions arise are: at team boundaries; culture; who is in charge, rationality/cognition; diversity; and collaborations. Three approaches - clarifying different levels of analysis, temporal factors, and overarching concepts - to resolving tensions are discussed. New conceptions of leadership and the importance of the larger cultural frame within which they are embedded are needed for the management of technology and innovation.

  15. Tissue oxygen tension in the stria vascularis.

    Science.gov (United States)

    Nagahara, K; Miyake, Y; Aoyama, T; Ogino, F

    1988-01-01

    Tissue oxygen tension in the stria vascularis was successfully measured in cats using the polarographic technique. A correlation study using the differential coefficient between oxygen tension in the stria vascularis and systemic blood pressure proved that vascular autoregulation is present in the mean systemic blood pressure range between 40 and 80 mmHg. The anatomical findings and the response patterns to different gas inhalations indicated that the type of vascular regulation present is more closely related to chemical control than to auto-regulation.

  16. Interfacial (o/w) properties of naphthetic acids and metal naphthenates, naphtenic acid characterization and metal naphthenate inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Brandal, Oeystein

    2005-07-01

    Deposition of metal naphthenates in process facilities is becoming a huge problem for petroleum companies producing highly acidic crudes. In this thesis, the main focus has been towards the oil-water (o/w) interfacial properties of naphthenic acids and their ability to react with different divalent cations across the interface to form metal naphthenates. The pendant drop technique was utilized to determine dynamic interfacial tensions (IFT) between model oil containing naphthenic acid, synthetic as well as indigenous acid mixtures, and pH adjusted water upon addition of different divalent cations. Changes in IFT caused by the divalent cations were correlated to reaction mechanisms by considering two reaction steps with subsequent binding of acid monomers to the divalent cation. The results were discussed in light of degree of cation hydration and naphthenic acid conformation, which affect the interfacial conditions and thus the rate of formation of 2:1 complexes of acid and cations. Moreover, addition of non-ionic oil-soluble surfactants used as basis compounds in naphthenate inhibitors was found to hinder a completion of the reaction through interfacial dilution of the acid monomers. Formation and stability of metal naphthenate films at o/w interfaces were studied by means of Langmuir technique with a trough designed for liquid-liquid systems. The effects of different naphthenic acids, divalent cations, and pH of the subphase were investigated. The results were correlated to acid structure, cation hydration, and degree of dissociation, which all affect the film stability against compression. Naphthenic acids acquired from a metal naphthenate deposit were characterized by different spectroscopic techniques. The sample was found to consist of a narrow family of 4-protic naphthenic acids with molecular weights around 1230 g/mol. These acids were found to be very o/w interfacially active compared to normal crude acids, and to form Langmuir monolayers with stability

  17. Spontaneous Interfacial Dipole Orientation Effect of Acetic Acid Solubilized PFN.

    Science.gov (United States)

    Wang, Cong; Luo, Yinqi; Zheng, Jieming; Liu, Linlin; Xie, Zengqi; Huang, Fei; Yang, Bing; Ma, Yuguang

    2018-03-28

    Poly[(9,9-dioctyl-2,7-fluorene)- alt-(9,9-bis(3'-( N, N-dimethylamino)propyl)-2,7-fluorene)] (PFN) is a very important interfacial modifier in organic photovoltaic and organic light-emitting diodes to improve device performance, where their molecular dipole has been regarded to play a key role. In this work, we have reported a spontaneous interfacial dipole orientation effect in acetic acid dissolved PFN, which is strongly related to the interfacial dipole and the corresponding device performance. In direct spin-coating, the interfacial dipole is 1.08 Debye with interfacial contact angle 84.8°, whereas after self-assembly of 10 min, the interfacial dipole is balanced at 4.21 Debye, with the interfacial contact angle decreasing to 76.8°. Without strong interaction with the substrate, the energy of upward amine groups is much lower than that of downward ones in theoretical simulation, which would be the driving force of this spontaneous process. The preferred conformations of PFN molecules on hydroxylated substrates have over 99% amine groups outward, and the theoretical average dipole calculated from the weight of these conformations is 4.48 Debye, which is close to the experimental result and indicates a high ratio of upward amine groups in self-assembled films. This effect obviously changes the device performance, such as an obvious positive threshold voltage shift in transistors and a distinct increase of the short-circuit current/open-circuit voltage in organic solar cells. This effect provides a deeper understanding of the PFN interlayer mechanism and has potential application in optoelectronic devices.

  18. Sensitivity study of tensions in distribution networks with respect to injected powers

    International Nuclear Information System (INIS)

    Tencio Alfaro, Ernie Fernando

    2013-01-01

    A study of the sensitivity of tension is submitted to small changes of active and reactive power of distributed generators (DG) of a 11 kV radial system of 8 circuits with 75 rods, in which 22 bars with DG and 38 bars with loads. The sensitivities are obtained for 6 load models 3 relations R / X of the lines interconnecting the distributed system, 3 equivalents of Thevenin and high load conditions with low generation and low load with high part of the DG and bars load. The study has obtained to determine which operating conditions of the system have presented the greatest tension sensitivities. A description of the theory of modeling loads and motor is developed for electrical power systems. The several ways to obtain the sensitivity matrix of tension are explained as central axis. (author) [es

  19. Effect of Ageing on the Passive and Active Tension and Pharmacodynamic Characteristics of Rat Coronary Arteries

    DEFF Research Database (Denmark)

    Sheykhzade, Majid; Simonsen, Anja Hviid; Boonen, Harrie C.M.

    2012-01-01

    The influence of ageing on the passive and active tension and pharmacodynamic characteristics of intramural coronary arteries from 3-month-old and 2-year-old male Wistar rats was investigated using an isometric myograph. The passive vessel wall tension measured in Ca2+-free physiological salt...... solution at L0 was significantly greater in arteries from old rats (1.46 ± 0.10 Nm–1, n = 7) than in young rats (1.13 ± 0.13 Nm–1, n = 6). However, the maximal active tension at L0 was similar. The spontaneous myogenic tone was increased by age and the vasorelaxation induced by extracellular K...... from both young and old rats. The slopes of the regression lines of the Schild plots were not significantly different from unity and the estimated pKB values for ketanserin were similar. In conclusion, ageing is associated with changes in passive mechanical characteristics as well as changes...

  20. Solid, liquid, and interfacial properties of TiAl alloys: parameterization of a new modified embedded atom method model.

    Science.gov (United States)

    Sun, Shoutian; Ramachandran, Bala Ramu; Wick, Collin D

    2018-02-21

    New interatomic potentials for pure Ti and Al, and binary TiAl were developed utilizing the second nearest neighbour modified embedded-atom method (MEAM) formalism. The potentials were parameterized to reproduce multiple properties spanning bulk solids, solid surfaces, solid/liquid phase changes, and liquid interfacial properties. This was carried out using a newly developed optimization procedure that combined the simple minimization of a fitness function with a genetic algorithm to efficiently span the parameter space. The resulting MEAM potentials gave good agreement with experimental and DFT solid and liquid properties, and reproduced the melting points for Ti, Al, and TiAl. However, the surface tensions from the model consistently underestimated experimental values. Liquid TiAl's surface was found to be mostly covered with Al atoms, showing that Al has a significant propensity for the liquid/air interface.

  1. El metamodelo meditativo y cefalea tensional. The meditative metamodel and tensional headache.

    OpenAIRE

    Bestard Bizet, Rafael; Batista González, Antonio; Escobar de la Torre, José Carlos; Bestard Silva, Dalia Del Carmen

    2014-01-01

    El metamodelo meditativo y cefalea tensional. The meditative metamodel and tensional headache. Resumen. La cefalea tensional se ha convertido en un verdadero fustigador de la sociedad moderna ocasionando verdaderos estragos en la salud y en la economía colectiva e individual. Aunque se hacen ingentes esfuerzos por paliar sus nefastos efectos, estos todavía resultan insuficientes e ineficientes. El presente trabajo constituye el primer intento en nuestro país de evaluar la efectividad de la me...

  2. Lattice-Boltzmann Modeling of Interfacial Dynamics in Porous Media

    Science.gov (United States)

    Porter, M. L.; Coon, E. T.; Kang, Q.; Carey, J. W.

    2012-12-01

    Traditional continuum scale multiphase flow models rely heavily on average properties and constitutive relationships that do not always accurately represent the underlying physics affecting flow and transport at the pore scale. These models are typically based on heuristic extensions of Darcy's law, rather than formally upscaling conservation principles that account for the microscale physics. As a result, constitutive relationships, such as capillary pressure and relative permeability, are highly simplified. It has been recognized that continuum scale multiphase flow models must include gradients of saturation and specific fluid-fluid interfacial area, in addition to the Darcy pressure gradient, as driving forces for the flow of multiple fluids in porous media. In this work, we investigate interfacial dynamics in porous media using a multicomponent lattice-Boltzmann simulator. We present simulations of drainage and imbibition in 2D and 3D heterogeneous porous media. We validate the simulations by comparing specific interfacial area estimates with those obtained from experiments. In addition, we present estimates of continuum scale interfacial velocity and the production/destruction of specific interfacial area.

  3. Transcutaneous oxygen tension in imminent foot gangrene

    DEFF Research Database (Denmark)

    Tønnesen, K H

    1978-01-01

    Transcutaneous oxygen tension at 44 degree C and maximal isotope clearance (90m Tc-pretechnetate + histramine) just proximal to the 1st toe and systolic toe blood pressure (strain gauge) were studied on a tilt table in patients with various degrees of obstructive arteriosclerotic disease. In legs...

  4. Inclusion and Participation: Working with the Tensions

    Directory of Open Access Journals (Sweden)

    Gideon Calder

    2011-12-01

    Full Text Available Democracy is crucially about inclusion: a theory of democracy must account for who is to be included in the democratic process, how, and on what terms. Inclusion, if conceived democratically, is fraught with tensions. This article identifies three such tensions, arising respectively in: (i the inauguration of the democratic public; (ii enabling equal participation; and (iii the relationship between instrumental and non-instrumental accounts of democracy’s value. In each case, I argue, rather than seeking somehow to dissolve or avoid such tensions, theories of democracy should allow us to live with their implications reflexively: to work with them. Such tensions are counter-democratic to the extent that they derail what Nancy Fraser calls “participatory parity,” under which citizens count as “full partners in social interaction.” But the extent to which they do this is not itself dependent on points of paradox in the very idea of inclusion. Such parity relies on complex factors, social and economic, which democratic institutions and procedures will not by themselves address. To achieve full democratic inclusion we must already have addressed such factors; no account of democracy itself, however finely-tuned, will do this.

  5. On the role of the string tension

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, R.; Barcelos-Neto, J. (Universidade Federal do Rio de Janeiro, RJ (Brazil). Inst. de Fisica)

    1991-01-10

    We study in detail the role played by the tension in the quantum algebra of constraints for bosonic and spinning strings, from the point of view of the BRST/BFV formalism. We observe why the well-known critical dimensions D=10 and D=26 can survive in the tensionless case. (orig.).

  6. Five tensions between science and democracy

    Energy Technology Data Exchange (ETDEWEB)

    Guston, D.J.

    1995-12-31

    The historical aspects of dialogue between the scientific establishments and the congress are used to illustrate and define the continuing tensions between these parties since 1880. Five areas are addressed as how best to cope and deal with the issues which in all probability will not go away. 1 ref.

  7. Coexisting tensions between the 'traditionmodernity' and the ...

    African Journals Online (AJOL)

    Coexisting tensions between the 'traditionmodernity' and the 'sustainability- integration' approaches to urban development policy and planning practices in Botswana. ... exists at several levels and manifest in urban planning's preoccupation with the physicality of spatial forms, often justified in the embracing of globalization.

  8. Surface Tension Measurements with a Smartphone

    Science.gov (United States)

    Goy, Nicolas-Alexandre; Denis, Zakari; Lavaud, Maxime; Grolleau, Adrian; Dufour, Nicolas; Deblais, Antoine; Delabre, Ulysse

    2017-01-01

    Smartphones are increasingly used in higher education and at university in mechanics, acoustics, and even thermodynamics as they offer a unique way to do simple science experiments. In this article, we show how smartphones can be used in fluid mechanics to measure surface tension of various liquids, which could help students understand the concept…

  9. Multiple Intelligences: Its Tensions and Possibilities

    Science.gov (United States)

    Eisner, Elliot W.

    2004-01-01

    This article explores the tensions between Howard Gardner's theory of multiple intelligences and current educational policies emphasizing standardized and predictable outcomes. The article situates Gardner's theory within the historical interests among psychometricians in identifying those core processes that constitute human intelligence.…

  10. The tension nose: open structure rhinoplasty approach.

    Science.gov (United States)

    Johnson, C M; Godin, M S

    1995-01-01

    The term tension nose is known to many rhinoplastic surgeons, yet confusion exists as to its precise meaning. We define the tension deformity as excessive growth of the quadrilateral cartilage, resulting in a high nasal dorsum and anterior and sometimes inferior displacement of the nasal tip cartilages. A review of the surgical literature shows that little attention has been given to the evaluation and management of this problem. We reviewed 50 consecutive primary rhinoplasty candidates and found that 46 percent had some manifestation of tension deformity that required correction at the time of surgery. The techniques of open structure rhinoplasty are ideally suited to manage the tension nose. The essence of correction is a deprojection-reprojection process. First, excessive elements of the septal cartilage and anterior nasal spine, which comprise what we have termed the nasal pedestal, are reduced, resulting in tip deprojection. Open structure methods are then employed to achieve reprojection of the domes by using cartilage grafts and suturing techniques to build strength, support, and elegance into the nasal tip.

  11. Tenure Tensions: Out in the Enchanted Forest

    Science.gov (United States)

    Tyler, Jo A.

    2010-01-01

    The tenure track in higher education represents a path shrouded in a fair degree of mystery. This essay provides the perspective of a middle-aged, second-career tenure track faculty member on the vagaries of progressing down the track as an out lesbian. Three dialectics that build tension into the process--covering-creating, evaluation-liberation,…

  12. Influence of colour symmetry on string tension

    International Nuclear Information System (INIS)

    Yukalov, V.I.; Yukalova, E.P.; Shanenko, A.A.

    1994-01-01

    The ratio of the fundamental string tension in the SU(3) pure (quarkless) gauge theory to that in the SU(2) gluonic system is estimated within a statistical model approach to the description of the QCD thermodynamics. The obtained estimation is in agreement with the lattice evaluation of the ratio. 9 refs

  13. Surface tension of aqueous electrolyte solutions. Thermodynamics

    NARCIS (Netherlands)

    Drzymala, J.; Lyklema, J.

    2012-01-01

    A thermodynamic theory is developed for obtaining the enthalpic and entropic contributions to the surface excess Gibbs energy of electrolyte solutions from the dependence of the surface tension on concentration and temperature. For elaboration, accurate activity coefficients in solution as functions

  14. Normal tension glaucoma and Alzheimer disease

    DEFF Research Database (Denmark)

    Bach-Holm, Daniella; Kessing, Svend Vedel; Mogensen, Ulla

    2012-01-01

    PURPOSE: To investigate whether normal tension glaucoma (NTG) is associated with increased risk of developing dementia/Alzheimer disease (AD). METHODS: A total of 69 patients with NTG were identified in the case note files in the Glaucoma Clinic, University Hospital of Copenhagen (Rigshospitalet...

  15. Tension Builds over AFT Reform Agenda

    Science.gov (United States)

    Sawchuk, Stephen

    2012-01-01

    Can a teachers' union successfully be both a hardball-playing defender of its rights and a collaborative force for the common good? It is both a question of philosophy and, increasingly, one of policy direction for the American Federation of Teachers (AFT), whose biennial convention in Detroit showed delegates grappling with the tension between…

  16. Educational Leadership: Key Challenges and Ethical Tensions

    Science.gov (United States)

    Duignan, Patrick

    2007-01-01

    "Educational Leadership" is a major research book on contemporary leadership challenges for educational leaders. In this groundbreaking new work, educational leaders in schools, including teachers, are provided with ways of analysing and resolving common but complex leadership challenges. Ethical tensions inherent in these challenges are…

  17. Molecular Level Manipulation of Interfacial Charge Transport

    Science.gov (United States)

    Song, Charles Kiseok

    The bulk-heterojunction organic (BHJ) photovoltaics (OPVs) and lithium ion battery (LiB) have been extensively studied. Power conversion efficiency (PCE) of an OPV greater than 10% and utilizing group 4 elements as the anode to accommodate high capacity for LiBs are the goals of many studies. However, the currently ubiquitous hole-collecting layer of OPVs limit device performance and durability, and group 4 elements are unstable and brittle to be commercially produced. Thus, my thesis has focused on developing functional and durable interfacial layers (IFLs) for OPVs and characterizing flexible artificial solid-electrolyte interphase (SEI) for LiBs. In Chapter 2, a series of robust organosilane-based dipolar self-assembled monolayer (SAM) IFLs on the tin-doped indium oxide (ITO) anodes of OPVs are developed. These hydrophobic and amorphous IFLs modify anode work functions from 4.66 to 5.27 eV. Two series of Glass/ITO/SAM IFL/Active Layer/LiF/Al BHJ OPVs are fabricated, and a strong positive correlation between the electrochemically-derived heterogeneous electron transport rate constants (ks) and OPV PCEs are observed due to enhanced anode carrier extraction. In Chapter 3, a series of unusually denser organosilane-based SAM IFLs on ITO anodes of OPVs are developed. Precursor mixtures having short and long tail groups were simultaneously deposited to minimize sterical encumbrance and denser SAM IFLs are achieved. These heterogeneous supersaturated SAMs (SHSAMs), with PCE (7.62%) exceeding that of PEDOT:PSS IFL, are found to be 17% denser and enhances PCE by 54% versus comparable devices with homogeneous SAM IFLs due to enhanced charge selectivity and collection. In Chapter 4, libraries of electron affinities (EAs) of widely used conductive polymers are constructed by cyclic voltammetry (CV) in conventional and LiB media. The EAs of the conductive polymer films measured via CV in conventional (EAC) and Li+ battery (EAB) media could be linearly correlated by EAB = (1

  18. Evaluation of enthalpy of interfacial reactions from temperature dependency of interfacial equilibrium

    International Nuclear Information System (INIS)

    Kallay, Nikola; Cop, Ana

    2005-01-01

    Temperature dependency of equilibrium at metal oxide-aqueous electrolyte solution interface was analyzed by numerical simulation. Derivations of inner surface potential with respect to temperature were performed at constant values of several different parameters. When surface charge density in inner plane was kept constant the reasonable results were obtained, i.e. the electrostatic contribution to enthalpy of protonation of amphotheric surface sites was found to be positive in the pH region below the point of zero potential and negative above this point. All other examined possibilities produced opposite results. Derivation of empirical interfacial equilibrium constant at constant surface potential indicated that electrostatic effect on protonation entropy is negligible and that electrostatic contributions to reaction Gibbs energy and enthalpy are equal and directly related to the surface potential in the inner plane

  19. Exploratory experimental investigations on post-tensioned structural glass beams

    DEFF Research Database (Denmark)

    Louter, C.; Nielsen, Jens Henrik; Belis, J.

    2013-01-01

    This paper discusses two projects on post-tensioned glass beams, performed at EPFL and DTU, respectively. In these projects small scale glass beams (length of 1.5m and 1m) are post-tensioned by means of steel threaded rods tensioned at the beam ends. The purpose of post-tensioning glass beams...... is to enhance the initial failure stress of the glass and to obtain ductile (post-breakage) performance. From four-point bending tests on the post-tensioned glass beam specimens it is observed that these goals are reached. From the test results it is concluded that post-tensioning glass beams is a feasible...

  20. Dynamics of two-phase interfaces and surface tensions: A density-functional theory perspective

    Science.gov (United States)

    Yatsyshin, Petr; Sibley, David N.; Duran-Olivencia, Miguel A.; Kalliadasis, Serafim

    2016-11-01

    Classical density functional theory (DFT) is a statistical mechanical framework for the description of fluids at the nanoscale, where the inhomogeneity of the fluid structure needs to be carefully accounted for. By expressing the grand free-energy of the fluid as a functional of the one-body density, DFT offers a theoretically consistent and computationally accessible way to obtain two-phase interfaces and respective interfacial tensions in a ternary solid-liquid-gas system. The dynamic version of DFT (DDFT) can be rigorously derived from the Smoluchowsky picture of the dynamics of colloidal particles in a solvent. It is generally agreed that DDFT can capture the diffusion-driven evolution of many soft-matter systems. In this context, we use DDFT to investigate the dynamic behaviour of two-phase interfaces in both equilibrium and dynamic wetting and discuss the possibility of defining a time-dependent surface tension, which still remains in debate. We acknowledge financial support from the European Research Council via Advanced Grant No. 247031 and from the Engineering and Physical Sciences Research Council of the UK via Grants No. EP/L027186 and EP/L020564.

  1. Transitions of tethered chain molecules under tension.

    Science.gov (United States)

    Luettmer-Strathmann, Jutta; Binder, Kurt

    2014-09-21

    An applied tension force changes the equilibrium conformations of a polymer chain tethered to a planar substrate and thus affects the adsorption transition as well as the coil-globule and crystallization transitions. Conversely, solvent quality and surface attraction are reflected in equilibrium force-extension curves that can be measured in experiments. To investigate these effects theoretically, we study tethered chains under tension with Wang-Landau simulations of a bond-fluctuation lattice model. Applying our model to pulling experiments on biological molecules we obtain a good description of experimental data in the intermediate force range, where universal features dominate and finite size effects are small. For tethered chains in poor solvent, we observe the predicted two-phase coexistence at transitions from the globule to stretched conformations and also discover direct transitions from crystalline to stretched conformations. A phase portrait for finite chains constructed by evaluating the density of states for a broad range of solvent conditions and tensions shows how increasing tension leads to a disappearance of the globular phase. For chains in good solvents tethered to hard and attractive surfaces we find the predicted scaling with the chain length in the low-force regime and show that our results are well described by an analytical, independent-bond approximation for the bond-fluctuation model for the highest tensions. Finally, for a hard or slightly attractive surface the stretching of a tethered chain is a conformational change that does not correspond to a phase transition. However, when the surface attraction is sufficient to adsorb a chain it will undergo a desorption transition at a critical value of the applied force. Our results for force-induced desorption show the transition to be discontinuous with partially desorbed conformations in the coexistence region.

  2. Interfacial dynamic and dilational rheology of polyelectrolyte/surfactant two-component nanoparticle systems at air–water interface

    International Nuclear Information System (INIS)

    Tong, L.J.; Bao, M.T.; Li, Y.M.; Gong, H.Y.

    2014-01-01

    Graphical abstract: - Highlights: • DTAB/PSS mixture can self-assemble nanoparticles in bulk solution. • The nanoparticles can adsorb at the interface forming a nanoparticle monolayer. • The nanoparticles spread at the interface undergo a disassembly process with time. • The nanoparticle monolayer presents peculiar dilational viscoelastic behavior. - Abstract: The interfacial characteristics of nanoparticles and consequent inter-particle interactions at the interface are poorly understood. In this work, the interfacial dynamic and corresponding dilational surface rheology of self-assembled polyelectrolyte/surfactant nanoparticles at the air–water interface are characterized. The nanoparticles are prepared from dodecyltrimethylammonium (DTAB) and poly (sodium 4-styrene-sulfonate) (PSS) by mixing them in aqueous solution. The interfacial dynamic characteristics have been carried out by comparing the surface pressure with the dilational rheological response of these nanoparticles at interface. The results indicate that this type of nanoparticles can adsorb at the interface forming a nanoparticle monolayer, which leads to the surface tension decreased markedly. The dependence of surface pressure on time shows the instability and disassembly process of nanoparticles at the interface. On the basis of these observations, it is proposed that the nanoparticles undergo a dynamic process that interface induced nanoparticles disassembly into DTAB/PSS complexes. The presence of PSS in the subphase can promote the process of nanoparticles disassembly. A transition point in dilational elasticity and viscosity response of the nanoparticles versus oscillation frequency further validate the micro dynamic process of nanoparticles and the formation of polyelectrolyte/surfactant complex monolayer at the interface

  3. The influence of interfacial properties on the two-phase liquid flow of organic contaminants in groundwater

    International Nuclear Information System (INIS)

    Demond, A.H.; Desai, F.N.; Hayes, K.F.

    1992-01-01

    DOE's waste sites are contaminated with a variety of organic liquids. Because of their low solubility in water, organic liquids such as these will persist as separate liquid phases and be transported as such in the subsurface. Thus, an improved understanding of the factors influencing the movement of a separate organic liquid phase in the subsurface is important to DOE's efforts to control groundwater contamination. Wettability is sometimes cited as the most important factor influencing two-phase flow in porous media. The wetting phase migrates preferentially through the smaller pores, whereas the nonwetting phase is concentrated in the larger pores. Typically, aquifers are thought of as strongly water-wet, implying that the organic liquid preferentially occupies the larger pores. But in fact, that state depends on the properties of the three interfaces of the system: between the organic liquid and water, water and the solid, and the organic liquid and the solid. Characteristics of the system which affect the interfacial properties also impact the wettability, such as the nature of the aquifer solids' surfaces, the composition of the goundwater and the properties of the organic contaminant. The alteration of wettability at DOE waste sites may be dominated by the presence of co-contaminants such as organic acids and bases which behave as surface-active agents or surfactants. Because of their physicochemical nature, surfactants will sorb preferentially at the interfaces of the system, thereby impacting the wettability and the distribution of the liquids in the porous medium. The over-all objective of this research was to determine how changes in interfacial properties affect two-phase flow. Specifically, the objective was to examine the effect of surfactant sorption on capillary pressure relationships by correlating measurements of sorption, zeta potential, interfacial tension and contact angle, with changes in the capillary pressure-saturation relationships

  4. Uncertainty analysis of an interfacial area reconstruction algorithm and its application to two group interfacial area transport equation validation

    Energy Technology Data Exchange (ETDEWEB)

    Dave, A.J., E-mail: akshayjd@umich.edu [Department of Nuclear Engineering and Rad. Sciences, University of Michigan, Ann Arbor, MI 48105 (United States); Manera, A. [Department of Nuclear Engineering and Rad. Sciences, University of Michigan, Ann Arbor, MI 48105 (United States); Beyer, M.; Lucas, D. [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Fluid Dynamics, 01314 Dresden (Germany); Prasser, H.-M. [Department of Mechanical and Process Engineering, ETH Zurich, 8092 Zurich (Switzerland)

    2016-12-15

    Wire mesh sensors (WMS) are state of the art devices that allow high resolution (in space and time) measurement of 2D void fraction distribution over a wide range of two-phase flow regimes, from bubbly to annular. Data using WMS have been recorded at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) (Lucas et al., 2010; Beyer et al., 2008; Prasser et al., 2003) for a wide combination of superficial gas and liquid velocities, providing an excellent database for advances in two-phase flow modeling. In two-phase flow, the interfacial area plays an integral role in coupling the mass, momentum and energy transport equations of the liquid and gas phase. While current models used in best-estimate thermal-hydraulic codes (e.g. RELAP5, TRACE, TRACG, etc.) are still based on algebraic correlations for the estimation of the interfacial area in different flow regimes, interfacial area transport equations (IATE) have been proposed to predict the dynamic propagation in space and time of interfacial area (Ishii and Hibiki, 2010). IATE models are still under development and the HZDR WMS experimental data provide an excellent basis for the validation and further advance of these models. The current paper is focused on the uncertainty analysis of algorithms used to reconstruct interfacial area densities from the void-fraction voxel data measured using WMS and their application towards validation efforts of two-group IATE models. In previous research efforts, a surface triangularization algorithm has been developed in order to estimate the surface area of individual bubbles recorded with the WMS, and estimate the interfacial area in the given flow condition. In the present paper, synthetically generated bubbles are used to assess the algorithm’s accuracy. As the interfacial area of the synthetic bubbles are defined by user inputs, the error introduced by the algorithm can be quantitatively obtained. The accuracy of interfacial area measurements is characterized for different bubbles

  5. Uncertainty analysis of an interfacial area reconstruction algorithm and its application to two group interfacial area transport equation validation

    International Nuclear Information System (INIS)

    Dave, A.J.; Manera, A.; Beyer, M.; Lucas, D.; Prasser, H.-M.

    2016-01-01

    Wire mesh sensors (WMS) are state of the art devices that allow high resolution (in space and time) measurement of 2D void fraction distribution over a wide range of two-phase flow regimes, from bubbly to annular. Data using WMS have been recorded at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) (Lucas et al., 2010; Beyer et al., 2008; Prasser et al., 2003) for a wide combination of superficial gas and liquid velocities, providing an excellent database for advances in two-phase flow modeling. In two-phase flow, the interfacial area plays an integral role in coupling the mass, momentum and energy transport equations of the liquid and gas phase. While current models used in best-estimate thermal-hydraulic codes (e.g. RELAP5, TRACE, TRACG, etc.) are still based on algebraic correlations for the estimation of the interfacial area in different flow regimes, interfacial area transport equations (IATE) have been proposed to predict the dynamic propagation in space and time of interfacial area (Ishii and Hibiki, 2010). IATE models are still under development and the HZDR WMS experimental data provide an excellent basis for the validation and further advance of these models. The current paper is focused on the uncertainty analysis of algorithms used to reconstruct interfacial area densities from the void-fraction voxel data measured using WMS and their application towards validation efforts of two-group IATE models. In previous research efforts, a surface triangularization algorithm has been developed in order to estimate the surface area of individual bubbles recorded with the WMS, and estimate the interfacial area in the given flow condition. In the present paper, synthetically generated bubbles are used to assess the algorithm’s accuracy. As the interfacial area of the synthetic bubbles are defined by user inputs, the error introduced by the algorithm can be quantitatively obtained. The accuracy of interfacial area measurements is characterized for different bubbles

  6. Germanium Nitride Interfacial Layer for Chalcogenide Random Access Memory Applications

    Science.gov (United States)

    Shen, Jie; Liu, Bo; Song, Zhitang; Xu, Cheng; Rao, Feng; Liang, Shuang; Feng, Songlin; Chen, Bomy

    2008-01-01

    This work reports on the performance improvement of a chalcogenide random access memory device by applying germanium nitride as an interfacial layer. The device with an 8-nm-thick GeN film was fabricated using standard 0.18 µm complementary metal oxide semiconductor technology. The as-deposited GeN is in the amorphous state and has a smooth surface. An electrical test showed that this N-deficient layer induces a lower threshold voltage during the operation. It is believed that the reduction mainly originated from the excellent interfacial properties, high electrical resistivity, and low thermal conductivity of GeN, which is would be a prospective interfacial material in CRAM devices.

  7. Liquid flow along a solid surface reversibly alters interfacial chemistry.

    Science.gov (United States)

    Lis, Dan; Backus, Ellen H G; Hunger, Johannes; Parekh, Sapun H; Bonn, Mischa

    2014-06-06

    In nature, aqueous solutions often move collectively along solid surfaces (for example, raindrops falling on the ground and rivers flowing through riverbeds). However, the influence of such motion on water-surface interfacial chemistry is unclear. In this work, we combine surface-specific sum frequency generation spectroscopy and microfluidics to show that at immersed calcium fluoride and fused silica surfaces, flow leads to a reversible modification of the surface charge and subsequent realignment of the interfacial water molecules. Obtaining equivalent effects under static conditions requires a substantial change in bulk solution pH (up to 2 pH units), demonstrating the coupling between flow and chemistry. These marked flow-induced variations in interfacial chemistry should substantially affect our understanding and modeling of chemical processes at immersed surfaces. Copyright © 2014, American Association for the Advancement of Science.

  8. Interfacial characteristics of hybrid nanocomposite under thermomechanical loading

    Science.gov (United States)

    Choyal, Vijay; Kundalwal, Shailesh I.

    2017-12-01

    In this work, an improved shear lag model was developed to investigate the interfacial characteristics of three-phase hybrid nanocomposite which is reinforced with microscale fibers augmented with carbon nanotubes on their circumferential surfaces. The shear lag model accounts for (i) radial and axial deformations of different transversely isotropic constituents, (ii) thermomechanical loads on the representative volume element (RVE), and (iii) staggering effect of adjacent RVEs. The results from the current newly developed shear lag model are validated with the finite element simulations and found to be in good agreement. This study reveals that the reduction in the maximum value of the axial stress in the fiber and the interfacial shear stress along its length become more pronounced in the presence of applied thermomechanical loads on the staggered RVEs. The existence of shear tractions along the RVE length plays a significant role in the interfacial characteristics and cannot be ignored.

  9. Ordering kinetics in model systems with inhibited interfacial adsorption

    DEFF Research Database (Denmark)

    Willart, J.-F.; Mouritsen, Ole G.; Naudts, J.

    1992-01-01

    . The results are related to experimental work on ordering processes in orientational glasses. It is suggested that the experimental observation of very slow ordering kinetics in, e.g., glassy crystals of cyanoadamantane may be a consequence of low-temperature activated processes which ultimately lead......The ordering kinetics in two-dimensional Ising-like spin moels with inhibited interfacial adsorption are studied by computer-simulation calculations. The inhibited interfacial adsorption is modeled by a particular interfacial adsorption condition on the structure of the domain wall between......, of the algebraic growth law, R(t)∼Atn, whereas the growth exponent, n, remains close to the value n=1/2 predicted by the classical Lifshitz-Allen-Cahn growth law for systems with nonconserved order parameter. At very low temperatures there is, however, an effective crossover to a much slower algebraic growth...

  10. Interfacial thermal conductance in multilayer graphene/phosphorene heterostructure

    International Nuclear Information System (INIS)

    Zhang, Ying-Yan; Pei, Qing-Xiang; Mai, Yiu-Wing; Lai, Siu-Kai

    2016-01-01

    Vertical integration of 2D materials has recently appeared as an effective method for the design of novel nano-scale devices. Using non-equilibrium molecular dynamics simulations, we study the interfacial thermal transport property of graphene/phosphorene heterostructures where phosphorene is sandwiched in between graphene. Various modulation techniques are thoroughly explored. We found that the interfacial thermal conductance at the interface of graphene and phosphorene can be enhanced significantly by using vacancy defects, hydrogenation and cross-plane compressive strain. By contrast, the reduction in the interfacial thermal conductance can be achieved by using cross-plane tensile strain. Our results provide important guidelines for manipulating the thermal transport in graphene/phosphorene based-nano-devices. (paper)

  11. Separation performance and interfacial properties of nanocomposite reverse osmosis membranes

    KAUST Repository

    Pendergast, MaryTheresa M.

    2013-01-01

    Four different types of nanocomposite reverse osmosis (RO) membranes were formed by interfacial polymerization of either polyamide (PA) or zeolite A-polyamide nanocomposite (ZA-PA) thin films over either pure polysulfone (PSf) or zeolite A-polysulfone nanocomposite (ZA-PSf) support membranes cast by wet phase inversion. All three nanocomposite membranes exhibited superior separation performance and interfacial properties relative to hand-cast TFC analogs including: (1) smoother, more hydrophilic surfaces (2) higher water permeability and salt rejection, and (3) improved resistance to physical compaction. Less compaction occurred for membranes with nanoparticles embedded in interfacially polymerized coating films, which adds further proof that flux decline associated with physical compaction is influenced by coating film properties in addition to support membrane properties. The new classes of nanocomposite membrane materials continue to offer promise of further improved RO membranes for use in desalination and advanced water purification. © 2011 Elsevier B.V.

  12. Role of corner interfacial area in uniqueness of capillary pressure-saturation- interfacial area relation under transient conditions

    Science.gov (United States)

    Godinez-Brizuela, Omar E.; Karadimitriou, Nikolaos K.; Joekar-Niasar, Vahid; Shore, Craig A.; Oostrom, Mart

    2017-09-01

    Capillary pressure (Pc) and phase saturation (Sw) in two-phase flow are well known to be hysteretically related. Thermodynamically-derived multiphase flow theories conjecture that this hysteresis will be lifted if specific interfacial area (anw) is included as a new state variable to create a unique Pc-S-anw surface. Specific interfacial area is defined as the total interfacial area per volume of a porous medium. Several studies have confirmed the existence of a unique Pc-Sw-anw surface under equilibrium conditions for a given porous medium. However, there is only one experimental work in the literature, where the uniqueness of this surface under transient conditions was questioned. However, in the data analysis only the terminal menisci were considered to calculate the specific interfacial area. In this paper, we investigate the uniqueness of Pc-S-anw surfaces with and without the inclusion of corner fluid-fluid interfacial area, under different dynamic conditions, in two different micro-models bearing two different (granular vs. triangulated) pore morphologies. We establish a systematic metric to analyze hysteresis under different hydrodynamic conditions.

  13. On the Mutual Effect of Viscoplasticity and Interfacial Damage Progression in Interfacial Fracture of Lead-Free Solder Joints

    Science.gov (United States)

    Maleki, Milad; Cugnoni, Joel; Botsis, John

    2011-10-01

    The main goal of this paper is to shed light on the effect of strain rate and viscoplastic deformation of bulk solder on the interfacial failure of lead-free solder joints. For this purpose, interfacial damage evolution and mode I fracture behavior of the joint were evaluated experimentally by performing stable fracture tests at different strain rates employing an optimized tapered double cantilever beam (TDCB) design. The viscoplastic behavior of the solder was characterized in shear, and the constitutive parameters related to the Anand model were determined. A rate-independent cohesive zone damage model was identified to best simulate the interfacial damage progression in the TDCB tests by developing a three-dimensional (3D) finite-element (FE) model and considering the viscoplastic response of the bulk solder. The influence of strain rate on the load capability and failure mode of the joint was clarified by analyzing the experimental and simulation results. It was shown how, at the lower strain rates, the normal stress generated at the interface is limited by the significant creep relaxation developed in the bulk solder and thus is not sufficiently high to initiate interfacial damage, whereas at higher rates, a large amount of the external energy is dissipated into interfacial damage development.

  14. Necessary Tension in Marine Risers Tension des colonnes montantes en mer

    Directory of Open Access Journals (Sweden)

    Lubinski A.

    2006-11-01

    Full Text Available The tension governing transverse static and dynamic deflections in a riser is not the actual tension but the so-called « effective tension » The concept of effective tension and effective compression is thoroughly explained, and means for calculating effective forces are given. Numerical examples are worked out for risers whose length is between 152 m (520 ft and 920 m (3020 ft. The reciprocal of maximum bending moment of the vicinity of the hall joint is plotted versus the effective tension of the ball joint. Bending moments used were obtained through use of static and dynamic computer programs applied ta a variety of conditions of wave loading, use or non-use of buoyant moterial sleeves, etc. The most important parameters affecting riser performance are the effective La tension régissant les déflections transversales statiques et dynamiques d'une colonne montante n'est pas la tension réelle mais ce qu'on appelle « la tension effective ». Le concept de tension ou de compression effective est expliqué en détail et la façon de calculer les forces effectives est indiquée dans cet article. Des exemples numériques sont développés pour des colonnes montantes de longueur comprise entre 152 m (520 ft et 920 m (3 020 ft. On a tracé la courbe de l'inverse du moment fléchissant en fonction de la tension effective à l'articulation. Les moments fléchissants utilisés ont été calculés par ordinateur en utilisant des programmes dynamiques et statiques pour des conditions variées d'action des vagues, la colonne montante étant ou non munie de manchettes de flottabilité, etc. Les deux paramètres les plus importants qui affectent le bon comportement d'une colonne montante sont la tension effective et la charge latérale.

  15. Interfacial friction in low flowrate vertical annular flow

    International Nuclear Information System (INIS)

    Kelly, J.M.; Freitas, R.L.

    1993-01-01

    During boil-off and reflood transients in nuclear reactors, the core liquid inventory and inlet flowrate are largely determined by the interfacial friction in the reactor core. For these transients, annular flow occurs at relatively modest liquid flowrates and at the low heat fluxes typical of decay heat conditions. The resulting low vapor Reynolds numbers, are out of the data range used to develop the generally accepted interfacial friction relations for annular flow. In addition, most existing annular flow data comes from air/liquid adiabatic experiments with fully developed flows. By contrast, in a reactor core, the flow is continuously developing along the heated length as the vapor flowrate increases and the flow regimes evolve from bubbly to annular flow. Indeed, the entire annular flow regime may exist only over tens of L/D's. Despite these limitations, many of the advanced reactor safety analysis codes employ the Wallis model for interfacial friction in annular flow. Our analyses of the conditions existing at the end-of-reflood in the PERICLES tests have indicated that the Wallis model seriously underestimates the interfacial shear for low vapor velocity cocurrent upflow. To extend the annular flow data base to diabatic low flowrate conditions, the DADINE tests were re-analyzed. In these tests, both pressure drop and local cross-section averaged void fractions were measured. Thus, both the wall and interfacial shear can be deduced. Based on the results of this analysis, a new correlation is proposed for interfacial friction in annular flow. (authors). 5 figs., 12 refs

  16. Static tensioning promotes hamstring tendons force relaxation more reliably than cycling tensioning.

    Science.gov (United States)

    Piedade, Sérgio Rocha; Dal Fabbro, Inácio Maria; Mischan, Martha Maria; Piedade, Cezar; Maffulli, Nicola

    2017-08-01

    Graft elongation might be a major reason for increased anterior laxity after anterior cruciate ligament (ACL) reconstruction. This study analyzed the force relaxation values and their stabilization when single strands of the gracilis and semitendinosus tendons underwent cyclic and static tensioning at 2.5% strain level, and compared the efficiency of static and cyclic tensioning in promoting force relaxation. Eighteen gracilis tendons and 18 semitendinosus tendons from nine male cadavers (mean age: 22.44years) were subjected to 10 in vitro cyclic loads at 2.5% strain level, or to a static load at 2.5% strain level. During cyclic loading, the reduction in force values tended to stabilize after the sixth cyclic load, while, in the case of static loading, this stabilization occurred by the second minute. Comparing static and cyclic loading, the gracilis tendon had similar mechanical responses in both conditions, while the semitendinosus tendon showed greater force relaxation in static compared with cyclic loading. Considering that the semitendinosus tendon is the main component of the hamstring graft, its biomechanical response to loading should guide the tensioning protocol. Therefore, static tensioning seems more effective for promoting force relaxation of the semitendinosus tendon than cyclic tensioning. The gracilis tendon showed a similar mechanical response to either tensioning protocols. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Interfacial charge distributions in carbon-supported palladium catalysts

    DEFF Research Database (Denmark)

    Rao, Radhika G.; Blume, Raoul; Hansen, Thomas Willum

    2017-01-01

    trends between the charge distribution at the palladium-carbon interface and the metal's selectivity for hydrogenation of multifunctional chemicals. These electronic effects are strong enough to affect the performance of large (~5 nm) Pd particles. Our results also demonstrate how simple thermal...... treatments can be used to tune the interfacial charge distribution, hereby providing a strategy to rationally design carbon-supported catalysts.Control over charge transfer in carbon-supported metal nanoparticles is essential for designing new catalysts. Here, the authors show that thermal treatments...... effectively tune the interfacial charge distribution in carbon-supported palladium catalysts with consequential changes in hydrogenation performance....

  18. Interfacial Effects in Polymer Membranes for Clean Energy

    Science.gov (United States)

    Soles, Christopher

    2013-03-01

    Polymeric membranes are critical components in several emerging clean energy technologies. Examples include proton exchange membranes for hydrogen fuel cells, anion exchange membranes for alkaline fuel cells, flow batteries, and even block copolymer membranes for solid electrolytes/separators in lithium ion and other battery technologies. In all of these examples the function of the membrane is to physically separate two reactive electrodes or reactants, but allow the transport or exchange of specific ions through the membrane between the active electrodes. The flow of the charged ionic species between the electrodes can be used to balance the flow of electrons through an external electrical circuit that connects the electrodes, thereby storing or delivering charge electrochemically. In this presentation I will review the use of polymeric membranes in electrochemical energy storage technologies and discuss the critical issues related to the membranes that hinder these technologies. In particular I will also focus on the role the polymer membrane interface on device performance. At some point the polymer membrane must be interfaced with an active electrode or catalyst and the nature of this interface can significantly impact performance. Simulations of device performance based on bulk membrane transport properties often fail to predict the actual performance and empirical interfacial impedance terms usually added to capture the device performance. In this presentation I will explore the origins of this interfacial impedance in the different types of fuel cell membranes (proton and alkaline) by creating model thin film membranes where all of the membrane can be considered interfacial. We then use these thin films as a surrogate for the interfacial regions of a bulk membrane and then quantify the structure, dynamics, and transport properties of water and ions in the confined interfacial films. Using neutron reflectivity, grazing incidence X-ray diffraction, and

  19. Density, Viscosity and Surface Tension of Binary Mixtures of 1-Butyl-1-Methylpyrrolidinium Tricyanomethanide with Benzothiophene.

    Science.gov (United States)

    Domańska, Urszula; Królikowska, Marta; Walczak, Klaudia

    2014-01-01

    The effects of temperature and composition on the density and viscosity of pure benzothiophene and ionic liquid (IL), and those of the binary mixtures containing the IL 1-butyl-1-methylpyrrolidynium tricyanomethanide ([BMPYR][TCM] + benzothiophene), are reported at six temperatures (308.15, 318.15, 328.15, 338.15, 348.15 and 358.15) K and ambient pressure. The temperature dependences of the density and viscosity were represented by an empirical second-order polynomial and by the Vogel-Fucher-Tammann equation, respectively. The density and viscosity variations with compositions were described by polynomials. Excess molar volumes and viscosity deviations were calculated and correlated by Redlich-Kister polynomial expansions. The surface tensions of benzothiophene, pure IL and binary mixtures of ([BMPYR][TCM] + benzothiophene) were measured at atmospheric pressure at four temperatures (308.15, 318.15, 328.15 and 338.15) K. The surface tension deviations were calculated and correlated by a Redlich-Kister polynomial expansion. The temperature dependence of the interfacial tension was used to evaluate the surface entropy, the surface enthalpy, the critical temperature, the surface energy and the parachor for pure IL. These measurements have been provided to complete information of the influence of temperature and composition on physicochemical properties for the selected IL, which was chosen as a possible new entrainer in the separation of sulfur compounds from fuels. A qualitative analysis on these quantities in terms of molecular interactions is reported. The obtained results indicate that IL interactions with benzothiophene are strongly dependent on packing effects and hydrogen bonding of this IL with the polar solvent.

  20. Reactive wetting of amorphous silica by molten Al–Mg alloys and their interfacial structures

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Laixin [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Shen, Ping, E-mail: shenping@jlu.edu.cn [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); Zhang, Dan [Editorial Office, Journal of Bionic Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China); Jiang, Qichuan [Key Laboratory of Automobile Materials (Ministry of Education), Department of Materials Science and Engineering, Jilin University, No. 5988 Renmin Street, Changchun 130025 (China)

    2016-07-30

    Highlights: • The wettability improves with increasing Mg concentration and temperature. • Reaction product zone consists of layered structures relating with Mg concentration. • Formation of MgAl{sub 2}O{sub 4} and MgO at the interface does not promote the wettability. • Formation of Mg{sub 2}Si plays a dominant role in promoting the wettability. • Anomalous recession of the triple line was mainly due to diminishing Mg in the alloy. - Abstract: The reactive wetting of amorphous silica substrates by molten Al–Mg alloys over a wide composition range was studied using a dispensed sessile drop method in a flowing Ar atmosphere. The effects of the nominal Mg concentration and temperature on the wetting and interfacial microstructures were discussed. The initial contact angle for pure Al on the SiO{sub 2} surface was 115° while that for pure Mg was 35° at 1073 K. For the Al–Mg alloy drop, it decreased with increasing nominal Mg concentration. The reaction zone was characterized by layered structures, whose formation was primarily controlled by the variation in the alloy concentration due to the evaporation of Mg and the interfacial reaction from the viewpoint of thermodynamics as well as by the penetration or diffusion of Mg, Al and Si from the viewpoint of kinetics. In addition, the effects of the reaction and the evaporation of Mg on the movement of the triple line were examined. The spreading of the Al–Mg alloy on the SiO{sub 2} surface was mainly attributed to the formation of Mg{sub 2}Si at the interface and the recession of the triple line to the diminishing Mg concentration in the alloy.

  1. Three-phase interactions and interfacial transport phenomena in coacervate/oil/water systems.

    Science.gov (United States)

    Dardelle, Gregory; Erni, Philipp

    2014-04-01

    Complex coacervation is an associative liquid/liquid phase separation resulting in the formation of two liquid phases: a polymer-rich coacervate phase and a dilute continuous solvent phase. In the presence of a third liquid phase in the form of disperse oil droplets, the coacervate phase tends to wet the oil/water interface. This affinity has long been known and used for the formation of core/shell capsules. However, while encapsulation by simple or complex coacervation has been used empirically for decades, there is a lack of a thorough understanding of the three-phase wetting phenomena that control the formation of encapsulated, compound droplets and the role of the viscoelasticity of the biopolymers involved. In this contribution, we review and discuss the interplay of wetting phenomena and fluid viscoelasticity in coacervate/oil/water systems from the perspective of colloid chemistry and fluid dynamics, focusing on aspects of rheology, interfacial tension measurements at the coacervate/solvent interface, and on the formation and fragmentation of three-phase compound drops. © 2013.

  2. Effect of dispersive long-range corrections to the pressure tensor: The vapour-liquid interfacial properties of the Lennard-Jones system revisited

    Energy Technology Data Exchange (ETDEWEB)

    Martínez-Ruiz, F. J.; Blas, F. J., E-mail: felipe@uhu.es [Departamento de Física Aplicada, Universidad de Huelva, 21071 Huelva (Spain); Centro de Investigación de Física Teórica y Matemática, Universidad de Huelva, 21071 Huelva (Spain); Mendiboure, B. [Laboratoire des Fluides Complexes et leurs Réservoirs, UMR5150, Université de Pau et des Pays de l’Adour, B. P. 1155, Pau Cedex 64014 (France); Moreno-Ventas Bravo, A. I. [Centro de Investigación de Física Teórica y Matemática, Universidad de Huelva, 21071 Huelva (Spain); Departamento de Geología, Facultad de Ciencias Experimentales, Universidad de Huelva, 21071 Huelva (Spain)

    2014-11-14

    We propose an extension of the improved version of the inhomogeneous long-range corrections of Janeček [J. Phys. Chem. B 110, 6264–6269 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] to account for the intermolecular potential energy of spherical, rigid, and flexible molecular systems, to deal with the contributions to the microscopic components of the pressure tensor due to the dispersive long-range corrections. We have performed Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of spherical Lennard-Jones molecules with different cutoff distances, r{sub c} = 2.5, 3, 4, and 5σ. In addition, we have also considered cutoff distances r{sub c} = 2.5 and 3σ in combination with the inhomogeneous long-range corrections proposed in this work. The normal and tangential microscopic components of the pressure tensor are obtained using the mechanical or virial route in combination with the recipe of Irving and Kirkwood, while the macroscopic components are calculated using the Volume Perturbation thermodynamic route proposed by de Miguel and Jackson [J. Chem. Phys. 125, 164109 (2006)]. The vapour-liquid interfacial tension is evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the Test-Area methodology. In addition to the pressure tensor and the surface tension, we also obtain density profiles, coexistence densities, vapour pressure, critical temperature and density, and interfacial thickness as functions of temperature, paying particular attention to the effect of the cutoff distance and the long-range corrections on these properties. According to our results, the main effect of increasing the cutoff distance (at fixed temperature) is to sharpen the vapour-liquid interface, to decrease the vapour pressure, and to increase the width of the biphasic coexistence region. As a result, the interfacial

  3. Report about the contribution of new technologies to the burial of high and very-high voltage power lines; Rapport sur l'apport de nouvelles technologies dans l'enfouissement des lignes electriques a haute et tres haute tension

    Energy Technology Data Exchange (ETDEWEB)

    Kert, Ch. [Assemblee Nationale, 75 - Paris (France)

    2001-12-01

    Today, high voltage overhead power lines are badly perceived by the population in particular in urban areas and in areas with remarkable landscapes, for their visual impact on the environment and for their possible effect on human health. With the increase of the domestic and foreign power demand, the high voltage grid will develop in the future and the partial burial of power lines can be the first steps towards a solution to these problems. This report makes a worldwide status of the state-of-the-art of power line burial technologies, all voltages considered, and then focusses on the very-high voltage challenge which encounters the most important technological and economical constraints. The technical feasibility has been proven but the lowering of costs needs the development of a real European market of power lines burial. (J.S.)

  4. Interfacial rheology: an overview of measuring techniques and its role in dispersions and electrospinning.

    Science.gov (United States)

    Pelipenko, Jan; Kristl, Julijana; Rošic, Romana; Baumgartner, Saša; Kocbek, Petra

    2012-06-01

    Interfacial rheological properties have yet to be thoroughly explored. Only recently, methods have been introduced that provide sufficient sensitivity to reliably determine viscoelastic interfacial properties. In general, interfacial rheology describes the relationship between the deformation of an interface and the stresses exerted on it. Due to the variety in deformations of the interfacial layer (shear and expansions or compressions), the field of interfacial rheology is divided into the subcategories of shear and dilatational rheology. While shear rheology is primarily linked to the long-term stability of dispersions, dilatational rheology provides information regarding short-term stability. Interfacial rheological characteristics become relevant in systems with large interfacial areas, such as emulsions and foams, and in processes that lead to a large increase in the interfacial area, such as electrospinning of nanofibers.

  5. Tending the tensions in co-creation

    DEFF Research Database (Denmark)

    Phillips, Louise Jane

    -creation as a process of mutual learning to be valued at least as much as the outcome AND the neoliberal instrumentalisation of creativity in the service of social innovation and economic growth. The papers build on the themes of Knowledge and Power in Collaborative Research: A Reflexive Approach (Phillips, Kristiansen......Across fields of social practice, the harnessing of creativity in collaborative, dialogic processes of knowledge production is championed as a means to empower participants as agents and generate practice change. ‘Collaboration’, ‘dialogue’ and ‘participation’ have become buzzwords with a taken......-for-granted positive value. In the panel we de-romanticise “co-creation” and explore how it is enacted in particular organisational contexts, concentrating on context-specific tensions arising in the meeting between different knowledge forms and interests. These include tensions BETWEEN dialogic views of knowledge co...

  6. Surface tension and deformation in soft adhesion

    Science.gov (United States)

    Jensen, Katharine

    Modern contact mechanics was originally developed to account for the competition between adhesion and elasticity for relatively stiff deformable materials like rubber, but much softer sticky materials are ubiquitous in biology, engineering, and everyday consumer products. In such soft materials, the solid surface tension can also play an important role in resisting shape change, and significantly modify the physics of contact with soft matter. We report indentation and pull-off experiments that bring small, rigid spheres into adhesive contact with compliant silicone gel substrates, varying both the surface functionalization of the spheres and the bulk elastic properties of the gels. We map the resulting deformation profiles using optical microscopy and image analysis. We examine the substrate geometry in light of capillary and elastic theories in order to explore the interplay of surface tension and bulk elasticity in governing soft adhesion.

  7. Tensions of Teaching Media Literacy in Teacher Education

    Science.gov (United States)

    Ngomba-Westbrook, Nalova Elaine

    2013-01-01

    This study investigates the tensions a teacher educator faces in facilitating a media literacy teacher education course at the university level. Teaching tensions are conceptualized as a three-tier framework. At the first level, tensions may arise in the selection and application of pedagogies associated with critical and new/21st century…

  8. Tension Tests On Bored Piles In Sand

    DEFF Research Database (Denmark)

    Krabbenhøft, Sven; Clausen, Johan; Damkilde, Lars

    2006-01-01

    The lengths of the bored piles varied from 2 m to 6 m and all were of a diameter of 140 mm. The piles were tested to failure in tension and the load-displacement relations were recorded. The investigation has shown pronounced differences between the load bearing capacities obtained by different...... design methods. The methods proposed by Fleming et al. and Reese & O’Neill seem to produce the best match with the test results....

  9. Tension-induced binding of semiflexible biopolymers

    International Nuclear Information System (INIS)

    Benetatos, Panayotis; Heydt, Alice von der; Zippelius, Annette

    2014-01-01

    We investigate theoretically the effect of polymer tension on the collective behavior of reversibly binding cross-links. For this purpose, we employ a model of two weakly bending wormlike chains aligned in parallel by a tensile force, with a sequence of inter-chain binding sites regularly spaced along the contours. Reversible cross-links attach and detach at the sites with an affinity controlled by a chemical potential. In a mean-field approach, we calculate the free energy of the system and find the emergence of a free-energy barrier which controls the reversible (un)binding. The tension affects the conformational entropy of the chains which competes with the binding energy of the cross-links. This competition gives rise to a sudden increase in the fraction of bound sites as the tension increases. We show that this transition is related to the cross-over between weak and strong localization of a directed polymer in a pinning potential. The cross-over to the strongly bound state can be interpreted as a mechanism for force-stiffening which exceeds the capabilities of single-chain elasticity and thus available only to reversibly cross-linked polymers. (paper)

  10. Generalized surface tension bounds in vacuum decay

    Science.gov (United States)

    Masoumi, Ali; Paban, Sonia; Weinberg, Erick J.

    2018-02-01

    Coleman and De Luccia (CDL) showed that gravitational effects can prevent the decay by bubble nucleation of a Minkowski or AdS false vacuum. In their thin-wall approximation this happens whenever the surface tension in the bubble wall exceeds an upper bound proportional to the difference of the square roots of the true and false vacuum energy densities. Recently it was shown that there is another type of thin-wall regime that differs from that of CDL in that the radius of curvature grows substantially as one moves through the wall. Not only does the CDL derivation of the bound fail in this case, but also its very formulation becomes ambiguous because the surface tension is not well defined. We propose a definition of the surface tension and show that it obeys a bound similar in form to that of the CDL case. We then show that both thin-wall bounds are special cases of a more general bound that is satisfied for all bounce solutions with Minkowski or AdS false vacua. We discuss the limit where the parameters of the theory attain critical values and the bound is saturated. The bounce solution then disappears and a static planar domain wall solution appears in its stead. The scalar field potential then is of the form expected in supergravity, but this is only guaranteed along the trajectory in field space traced out by the bounce.

  11. Low-Level Laser Effects on Simulated Orthodontic Tension Side Periodontal Ligament Cells

    OpenAIRE

    Huang, Tsui-Hsien; Liu, Shiau-Lee; Chen, Chih-Lin; Shie, Ming-You; Kao, Chia-Tze

    2013-01-01

    Objective: The purpose of this study was to analyze proliferation, inflammation, and osteogenic effects on periodontal ligament (PDL) cells after low-level laser therapy (LLLT) under simulated orthodontic tension conditions. Background data: Low-level lasers affect fibroblast proliferation and collagen synthesis and reduce inflammation. Few studies have focused on the LLLT changes in the PDL caused by moving teeth. Materials and methods: A human PDL cell line was cultured in a −100 kPa tensio...

  12. Interfacial stresses in strengthened beam with shear cohesive zone ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... This paper presents an analytical solution, based on Smith and Teng's equations, for interfacial shear and normal stresses in reinforced concrete (RC) beams strengthened with a fibre reinforced polymer (FRP) plate. However, the shear stress–strain relationship is considered to be bilinear curve.

  13. Manipulation of interfacial instabilities by using a soft, deformable ...

    Indian Academy of Sciences (India)

    parameter regimes, it is also possible to enhance the flow instabilities by tuning the shear modulus of ... induces new fluid–solid interfacial instabilities both at zero and finite Reynolds number which are qualitatively .... A standard temporal linear stability analysis is carried out by imposing small perturbations on base state ...

  14. A demonstration of enhancements in interfacial rheological characterisations

    DEFF Research Database (Denmark)

    Hodder, Peter; Baldursdottir, Stefania G.

    we have compared the performance of two models of the new Discovery Hybrid Rheometer and the AR G2 rheometer when studying the interfacial adsorption of lysozyme (from hen egg white, Sigma-Aldrich, Denmark) using the double wall ring geometry. The results show great improvement in the detection limit...

  15. A comparative study regarding effects of interfacial ferroelectric ...

    Indian Academy of Sciences (India)

    A comparative study regarding effects of interfacial ferroelectric. Bi4Ti3O12 (BTO) layer on electrical characteristics of Au/n-Si structures. M YILDIRIM and M GÖKÇEN. ∗. Department of Physics, Faculty of Arts & Science, Düzce University, 81620 Düzce, Turkey. MS received 11 July 2012; revised 7 January 2013. Abstract.

  16. Phase transitions, interfacial fluctuations and hidden symmetries for ...

    Indian Academy of Sciences (India)

    Fluids adsorbed at micro-patterned and geometrically structured substrates can exhibit novel phase transitions and interfacial fluctuation effects distinct from those characteristic of wetting at planar, homogeneous walls. We review recent theoretical progress in this area paying particular attention to filling transitions pertinent ...

  17. Undergraduate Laboratory Experiment Modules for Probing Gold Nanoparticle Interfacial Phenomena

    Science.gov (United States)

    Karunanayake, Akila G.; Gunatilake, Sameera R.; Ameer, Fathima S.; Gadogbe, Manuel; Smith, Laura; Mlsna, Deb; Zhang, Dongmao

    2015-01-01

    Three gold-nanoparticle (AuNP) undergraduate experiment modules that are focused on nanoparticles interfacial phenomena have been developed. Modules 1 and 2 explore the synthesis and characterization of AuNPs of different sizes but with the same total gold mass. These experiments enable students to determine how particle size affects the AuNP…

  18. An Inverse Michaelis–Menten Approach for Interfacial Enzyme Kinetics

    DEFF Research Database (Denmark)

    Kari, Jeppe; Andersen, Morten; Borch, Kim

    2017-01-01

    Interfacial enzyme reactions are ubiquitous both in vivo and in technical applications, but analysis of their kinetics remains controversial. In particular, it is unclear whether conventional Michaelis–Menten theory, which requires a large excess of substrate, can be applied. Here, an extensive e...

  19. Impact of Interfacial Layers in Perovskite Solar Cells.

    Science.gov (United States)

    Cho, An-Na; Park, Nam-Gyu

    2017-10-09

    Perovskite solar cells (PCSs) are composed of organic-inorganic lead halide perovskite as the light harvester. Since the first report on a long-term-durable, 9.7 % efficient, solid-state perovskite solar cell, organic-inorganic halide perovskites have received considerable attention because of their excellent optoelectronic properties. As a result, a power conversion efficiency (PCE) exceeding 22 % was certified. Controlling the grain size, grain boundary, morphology, and defects of the perovskite layer is important for achieving high efficiency. In addition, interfacial engineering is equally or more important to further improve the PCE through better charge collection and a reduction in charge recombination. In this Review, the type of interfacial layers and their impact on photovoltaic performance are investigated for both the normal and the inverted cell architectures. Four different interfaces of fluorine-doped tin oxide (FTO)/electron-transport layer (ETL), ETL/perovskite, perovskite/hole-transport layer (HTL), and HTL/metal are classified, and their roles are investigated. The effects of interfacial engineering with organic or inorganic materials on photovoltaic performance are described in detail. Grain-boundary engineering is also included because it is related to interfacial engineering and the grain boundary in the perovskite layer plays an important role in charge conduction, recombination, and chargecarrier life time. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Synthesis of exfoliated PA66 nanocomposites via interfacial ...

    Indian Academy of Sciences (India)

    Nanocomposites of polyamide 66 (PA66) with layered silicate and silica (SiO2) nanoparticles were prepared via in situ interfacial polycondensation method. Hexamethylenediamine (HDMA) and adipoyl chloride(AdCl) were reacted in a two-phase media. Montmorillonite (NaMMT) and silica nanoparticles were added to ...

  1. Synthesis of exfoliated PA66 nanocomposites via interfacial ...

    Indian Academy of Sciences (India)

    et al [5] prepared polyamide reverse osmosis (RO) mem- branes by interfacial polymerization of trimesoylchloride. (TMC) and m-phenylenediamine (MPD) monomers over a polyethersulfone (PES) support layer. They evaluated the separation performance of the fabricated thin film compos- ite (TFC) membranes by a cross ...

  2. Effect of strong coupling on interfacial electron transfer dynamics in ...

    Indian Academy of Sciences (India)

    Unknown

    Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 e-mail: hnghosh@barc.gov.in. Abstract. Dynamics of interfacial electron transfer (ET) in ruthenium ..... As the localization takes place mostly on bpy-cat ligand, ILET process does not interfere much in the electron injection ...

  3. Green-Kubo relations for dynamic interfacial excess properties

    NARCIS (Netherlands)

    Sagis, L.M.C.

    2012-01-01

    In this paper we analyze the fluctuations of the in-plane interfacial excess fluxes in multiphase systems, in the context of the extended irreversible thermodynamics formalism. We derive expressions for the time correlation functions of the surface extra stress tensor, the surface mass flux vector,

  4. Measurement of Interfacial Area Production and Permeability within Porous Media

    International Nuclear Information System (INIS)

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

    2010-01-01

    An understanding of the pore-level interactions that affect multi-phase flow in porous media is important in many subsurface engineering applications, including enhanced oil recovery, remediation of dense non-aqueous liquid contaminated sites, and geologic CO 2 sequestration. Standard models of two-phase flow in porous media have been shown to have several shortcomings, which might partially be overcome using a recently developed model based on thermodynamic principles that includes interfacial area as an additional parameter. A few static experimental studies have been previously performed, which allowed the determination of static parameters of the model, but no information exists concerning the interfacial area dynamic parameters. A new experimental porous flow cell that was constructed using stereolithography for two-phase gas-liquid flow studies was used in conjunction with an in-house analysis code to provide information on dynamic evolution of both fluid phases and gas-liquid interfaces. In this paper, we give a brief introduction to the new generalized model of two-phase flow model and describe how the stereolithography flow cell experimental setup was used to obtain the dynamic parameters for the interfacial area numerical model. In particular, the methods used to determine the interfacial area permeability and production terms are shown.

  5. Summer Research Institute Interfacial and Condensed Phase Chemical Physics

    Energy Technology Data Exchange (ETDEWEB)

    Barlow, Stephan E.

    2004-10-01

    Pacific Northwest National Laboratory (PNNL) hosted its first annual Summer Research Institute in Interfacial and Condensed Phase Chemical Physics from May through September 2004. During this period, fourteen PNNL scientists hosted sixteen young scientists from eleven different universities. Of the sixteen participants, fourteen were graduate students; one was transitioning to graduate school; and one was a university faculty member.

  6. Hyper-cross-linked, hybrid membranes via interfacial polymerization

    NARCIS (Netherlands)

    Raaijmakers, Michiel

    2015-01-01

    Hyper-cross-linked, hybrid membranes consist of covalent networks of alternating organic and inorganic, or biological groups. This thesis reports on the preparation of such hybrid networks via interfacial polymerization. The structure-property relationships of the hybrid networks depend strongly on

  7. Interfacial nanorheology: Probing molecular mobility in mesoscopic polymeric systems

    Science.gov (United States)

    Sills, Scott E.

    Investigating the finite size limited structural relaxations in mesoscopic polymer systems is central to nanotechnological applications involving thin films, complex structures, and nanoscale phase-separated systems; for example, polymer electrolyte membranes, optoelectronic devices, and ultrahigh-density thermomechanical data storage (terabit recording). In such systems, bulk statistical averaging and continuum models are jeopardized. Interfacial constraints lead to bulk-deviating molecular dynamics and dictate material and transport properties. The objective of this dissertation is to provide insight to the exotic mesoscopic behaviors in thin films by developing novel rheological and tribological analytical methods based on scanning probe microscopy (SPM). Activation energies are deduced for the molecular motions associated with internal friction dissipation, and the temperature resolved length scale for cooperative motion during the glass transition is directly obtained for polystyrene. These results confirm the dynamical heterogeneity of the glass transition and reveal a crossover from intra- to inter-molecular relaxation in the transition regime. The impact of dimensional constraints on molecular mobility in ultrathin polymer films is explored through interfacial glass-transition profiles. With these profiles, a structural model of the rheological changes near interfacial boundaries is constructed as function of molecular weight and crosslinking density. The manifestation of interfacial constraints in nanotechnological applications is illustrated for thermomechanical recording, where rheological gradients near the substrate dictate the contact pressure and strain shielding at the substrate compromises film stability. A foundation for the critical aspects of interfacial stability is developed, and mechanically graded interfaces and modulus-matching techniques are explored as a means of improving the stability, durability, and stress transmission characteristics

  8. Interfacial shear stress in stratified flow in a horizontal rectangular duct

    Energy Technology Data Exchange (ETDEWEB)

    Lorencez, C.; Kawaji, M. [Univ. of Toronto (Canada); Murao, Y. [Tokushima Univ. (Japan)] [and others

    1995-09-01

    Interfacial shear stress has been experimentally examined for both cocurrent and countercurrent stratified wavy flows in a horizontal interfacial shear stress from the measurements were examined and the results have been compared with existing correlations. Some differences were found in the estimated interfacial shear stress from the measurements were examined and the results have been compared with existing correlations. Some differences were found in the estimated interfacial shear stress values at high gas flow rates which could be attributed to the assumptions and procedures involved in each method. The interfacial waves and secondary motions were also found to have significant effects on the accuracy of Reynolds stress and turbulence kinetic energy extrapolation methods.

  9. Investigation of the interfacial condition between bioceramic coatings and metallic substrates using guided waves

    Science.gov (United States)

    Saffari, Nader; Ong, Chuon-Szen

    2001-04-01

    The work reported here is on the characterization of the interfacial properties between plasma-sprayed Hydroxyapatite coatings on titanium substrates as used in cement-less hip orthopaedic implants. The phase velocity dispersion for the first Rayleigh-type mode for the coating-substrate system has been shown to be sensitive to the interfacial stiffness. Different interfacial conditions between the coating and substrate have been obtained by cyclic loading of the specimens in a four-point bend fatigue machine. The measured interfacial stiffness is then correlated with the interfacial fracture strength obtained by standard destructive shear tests.

  10. Temporomandibular disorders and tension-type headache.

    Science.gov (United States)

    Mongini, Franco

    2007-12-01

    Pathologies currently defined as temporomandibular disorders may be different in nature. Temporomandibular joint (TMJ) disorders and craniofacial and cervical myogenous pain (MP) are distinct pathologies but may be superimposed and share some etiologic factors. Tension-type headache (TTH) may often be associated with craniofacial and cervical pain, and the same pharmacologic and nonpharmacologic treatment may be efficacious for both. Psychiatric comorbidity (depression and/or anxiety disorder) is less frequent in sheer TMJ disorders, compared with MP and TTH. A screening for the presence of an underlying psychiatric disorder should be part of the clinical evaluation in patients suffering from headache and facial pain.

  11. Superficial tension: experimental model with simple materials

    Directory of Open Access Journals (Sweden)

    Tintori Ferreira, María Alejandra

    2012-09-01

    Full Text Available In this work appears a didactic offer based on an experimental activity using materials of very low cost, orientated to achieving that the student understand and interpret the phenomenon of superficial tension together with the importance of the modeling in sciences. It has as principal aim of education bring the student over to the mechanics of the static fluids and the intermolecular forces, combining scientific contents with questions near to the student what provides an additional motivation to the reflection of the scientific investigation.

  12. Cuerpo y subjetividad: materiales y tensiones

    OpenAIRE

    Cachorro, Gabriel

    2007-01-01

    En este artículo se efectúa un abordaje del tema cuerpo y subjetividad a través de un ejercicio exploratorio de sus materiales y tensiones. Las preguntas posibles de formular son: ¿Qué discusiones tenemos por debajo de la subjetividad corporal?, ¿cuáles son las raíces históricas de este tema?, ¿qué problemáticas lo atraviesan? La enunciación de estos interrogantes nos ayuda a establecer la posición de investigador y a explicitar los argumentos teóricos. Se desprende de esta propuest...

  13. Interpreting expressive performance through listener judgments of musical tension.

    Science.gov (United States)

    Farbood, Morwaread M; Upham, Finn

    2013-01-01

    This study examines listener judgments of musical tension for a recording of a Schubert song and its harmonic reduction. Continuous tension ratings collected in an experiment and quantitative descriptions of the piece's musical features, include dynamics, pitch height, harmony, onset frequency, and tempo, were analyzed from two different angles. In the first part of the analysis, the different processing timescales for disparate features contributing to tension were explored through the optimization of a predictive tension model. The results revealed the optimal time windows for harmony were considerably longer (~22 s) than for any other feature (~1-4 s). In the second part of the analysis, tension ratings for the individual verses of the song and its harmonic reduction were examined and compared. The results showed that although the average tension ratings between verses were very similar, differences in how and when participants reported tension changes highlighted performance decisions made in the interpretation of the score, ambiguity in tension implications of the music, and the potential importance of contrast between verses and phrases. Analysis of the tension ratings for the harmonic reduction also provided a new perspective for better understanding how complex musical features inform listener tension judgments.

  14. Shape accuracy optimization for cable-rib tension deployable antenna structure with tensioned cables

    Science.gov (United States)

    Liu, Ruiwei; Guo, Hongwei; Liu, Rongqiang; Wang, Hongxiang; Tang, Dewei; Song, Xiaoke

    2017-11-01

    Shape accuracy is of substantial importance in deployable structures as the demand for large-scale deployable structures in various fields, especially in aerospace engineering, increases. The main purpose of this paper is to present a shape accuracy optimization method to find the optimal pretensions for the desired shape of cable-rib tension deployable antenna structure with tensioned cables. First, an analysis model of the deployable structure is established by using finite element method. In this model, geometrical nonlinearity is considered for the cable element and beam element. Flexible deformations of the deployable structure under the action of cable network and tensioned cables are subsequently analyzed separately. Moreover, the influence of pretension of tensioned cables on natural frequencies is studied. Based on the results, a genetic algorithm is used to find a set of reasonable pretension and thus minimize structural deformation under the first natural frequency constraint. Finally, numerical simulations are presented to analyze the deployable structure under two kinds of constraints. Results show that the shape accuracy and natural frequencies of deployable structure can be effectively improved by pretension optimization.

  15. TBK1 duplication is found in normal tension and not in high tension ...

    Indian Academy of Sciences (India)

    Duplication in TANK-binding kinase 1 (TBK1) gene has been shown to be associated with normal tension glaucoma. (NTG), a subtype of the neurodegenerative disease glau- coma, which is the largest cause of irreversible blindness. A specific Taqman assay was used in exploring the genetic contribution of the duplication ...

  16. Nitinol Fatigue Investigation on Stent-Finish Specimens Using Tension-Tension Method

    Science.gov (United States)

    Lin, Z.; Pike, K.; Zipse, A.; Schlun, M.

    2011-07-01

    Nitinol fatigue strain limit versus both strain amplitude (range 0.25-1.25%) and mean strain (1.0, 2.0, and 4.0%) was investigated using a tension-tension method. In order to apply the fatigue testing results to a nitinol stent and evaluate stent fatigue performance, the dog-bone style specimens were processed from the same raw material common to implantable stent manufacturing, i.e., similar nitinol tubing, surface quality, and electropolished surface. To simulate a physiological environment, the tension-tension fatigue tests were conducted in water at 37 °C. This strain-controlled fatigue test was conducted with a run-out set at 106 cycles. The fatigue strain limit at 106 cycles as well as the mean strain effect and the effects of inclusions are discussed. Fatigue results appeared in a bi-modal pattern when the strain amplitude was at a level between too high, which made all specimens to fail, and too low, which allowed all specimens to survive.

  17. A polarized view on DNA under tension

    Science.gov (United States)

    van Mameren, Joost; Vermeulen, Karen; Wuite, Gijs J. L.; Peterman, Erwin J. G.

    2018-03-01

    In the past decades, sensitive fluorescence microscopy techniques have contributed significantly to our understanding of the dynamics of DNA. The specific labeling of DNA using intercalating dyes has allowed for quantitative measurement of the thermal fluctuations the polymers undergo. On the other hand, recent advances in single-molecule manipulation techniques have unraveled the mechanical and elastic properties of this intricate polymer. Here, we have combined these two approaches to study the conformational dynamics of DNA under a wide range of tensions. Using polarized fluorescence microscopy in conjunction with optical-tweezers-based manipulation of YOYO-intercalated DNA, we controllably align the YOYO dyes using DNA tension, enabling us to disentangle the rapid dynamics of the dyes from that of the DNA itself. With unprecedented control of the DNA alignment, we resolve an inconsistency in reports about the tilted orientation of intercalated dyes. We find that intercalated dyes are on average oriented perpendicular to the long axis of the DNA, yet undergo fast dynamics on the time scale of absorption and fluorescence emission. In the overstretching transition of double-stranded DNA, we do not observe changes in orientation or orientational dynamics of the dyes. Only beyond the overstretching transition, a considerable depolarization is observed, presumably caused by an average tilting of the DNA base pairs. Our combined approach thus contributes to the elucidation of unique features of the molecular dynamics of DNA.

  18. A demonstration of enhancements in interfacial rheological characterisations

    DEFF Research Database (Denmark)

    Hodder, Peter; Baldursdottir, Stefania G.

    projects and publications associated with the field of interfacial rheology. After previous experimentation by Dr. Stefania Baldursdottir, there was a keen interest in the ability to reduce the concentrations of proteins used for interfacial characterisations so that expensive therapeutically active...... proteins can be studied as well as the typically used model proteins as bovine serum albumin (BSA) and lysozyme. Previously there was a need for high enough concentrations to produce a signal strong enough to be measured, a limitation of the technology to date. With the introduction of the new Discovery...... into studying concentration below which a monolayer is formed and beyond, and so shows the benefits of enhanced sensitivity which has given rise to the potential to measure an even greater spectrum of interfaces and a means to determine the development of any interface with time or concentration. In this study...

  19. Contribution to the study of the interfacial diffusion

    International Nuclear Information System (INIS)

    Perinet, Francois.

    1975-07-01

    The diffusion behaviour of matrix-precipitate boundaries is the same as that of interphase boundaries prepared by welding. Therefore the latter can be used to measure diffusivity along interphase boundaries. Diffusion rates of silver along copper-silver interfaces prepared by welding single crystals have been measured. The interfacial diffusion coefficients deduced through different analytical solutions of the diffusion equations, yield for the activation energy and the frequency factor values close to: Q(i)=65kcal/mole Dsub(i)sup(o) delta=100cm 3 .s -1 . These results seem to indicate that, in agreement with Bondy's and Job's previous results, the activation energies for interfacial diffusion are high. Furthermore it is shown that the misorientation between the two phases building the interface has an influence on the measured diffusion coefficients [fr

  20. Friction mechanisms and interfacial slip at fluid-solid interfaces

    CERN Document Server

    Leger, L

    2003-01-01

    We present series of experiments based on near field laser velocimetry, developed to characterize the friction mechanisms at fluid-solid interfaces. For polymers, entangled polymer melts are sheared against smooth solid surfaces, covered by surface attached polymer chains of the same chemical species, having a controlled surface density. Direct measurements of the interfacial velocity and of the shear force allow identification of the molecular mechanisms of friction. Depending on the value of the inverse of the shear rate experienced by the polymer compared to the reptation time, the transition between a regime of high and a regime of low friction observed when increasing the shear rate can be related to disentanglement or to the extraction of the surface chains from the bulk polymer. Surfaces with adjusted friction properties can thus be designed by choosing chain anchored length and surface density. For simple fluids, the direct measurements of the interfacial velocity show that, contrary to the usual hypo...

  1. Electroosmosis of Powell-Eyring fluids under interfacial slip.

    Science.gov (United States)

    Goswami, Prakash; Mondal, Pranab Kumar; Dutta, Sanmitra; Chakraborty, Suman

    2015-03-01

    We investigate the EOF of a Powell-Eyring fluid through a slit microchannel, employing Navier slip boundary condition. Using an analytical scheme consistent with the homotopy perturbation method, we bring out the alteration in the underlying flow dynamics as attributable to the nonlinear interactions between fluid rheology and electrostatics over interfacial scales. We validate the approximate analytical solutions by comparing those with results from numerical analysis. We unveil a regime of phenomenal amplification in the net volumetric flow rate, realized as a consequence of an intricate interplay between interfacial electromechanics, slipping hydrodynamics, and the flow rheology. Our results may have far ranging consequences in the design of various biomicrofluidic devises/systems, which are often used for the manipulation of non-Newtonain fluids. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Symmetrical electroadhesives independent of different interfacial surface conditions

    Science.gov (United States)

    Guo, J.; Hovell, T.; Bamber, T.; Petzing, J.; Justham, L.

    2017-11-01

    Current electroadhesive actuators cannot produce stable electroadhesive forces on the same substrate with different interfacial surface interactions. It is, therefore, desirable to develop electroadhesive actuators that can generate stable adhesive forces on different surface conditions. A symmetrical electroadhesive pad that is independent of different interfacial scratch directions is developed and presented. A relative difference of only 6.4% in the normal force direction was observed when the electroadhesive was facing an aluminium plate with surface scratch directions of 0°, 45°, 90°, and 135°. This step-change improvement may significantly promote the application of electroadhesion technology. In addition, this manifests that significant performance improvements could be achieved via further investigations into electroadhesive designs.

  3. Enzymatically activated emulsions stabilised by interfacial nanofibre networks.

    Science.gov (United States)

    Moreira, Inês P; Sasselli, Ivan Ramos; Cannon, Daniel A; Hughes, Meghan; Lamprou, Dimitrios A; Tuttle, Tell; Ulijn, Rein V

    2016-03-07

    We report on-demand formation of emulsions stabilised by interfacial nanoscale networks. These are formed through biocatalytic dephosphorylation and self-assembly of Fmoc(9-fluorenylmethoxycarbonyl)dipeptide amphiphiles in aqueous/organic mixtures. This is achieved by using alkaline phosphatase which transforms surfactant-like phosphorylated precursors into self-assembling aromatic peptide amphiphiles (Fmoc-tyrosine-leucine, Fmoc-YL) that form nanofibrous networks. In biphasic organic/aqueous systems, these networks form preferentially at the interface thus providing a means of emulsion stabilisation. We demonstrate on-demand emulsification by enzyme addition, even after storage of the biphasic mixture for several weeks. Experimental (Fluorescence, FTIR spectroscopy, fluorescence microscopy, electron microscopy, atomic force microscopy) and computational techniques (atomistic molecular dynamics) are used to characterise the interfacial self-assembly process.

  4. Interfacial Dynamics of Abelian Domains: Differential Geometric Methods

    International Nuclear Information System (INIS)

    Owczarek, Robert M.; Makaruk, Hanna E.

    1997-11-01

    The equation: ReF'(T,Z)ZF'(T,Z) = 1 for conformal maps f(t,z) is important in interfacial dynamics. We extend the results by Gustafsson on existence and uniqueness of solutions of this equation from the case when f(t,z) is a rational function of z to the case when the spatial derivative f'(t,z) is rational

  5. Interfacial assembly of turnip yellow mosaic virus nanoparticles.

    Science.gov (United States)

    Kaur, Gagandeep; He, Jinbo; Xu, Ji; Pingali, Saivenkatesh; Jutz, Günther; Böker, Alexander; Niu, Zhongwei; Li, Tao; Rawlinson, Dustin; Emrick, Todd; Lee, Byeongdu; Thiyagarajan, Pappannan; Russell, Thomas P; Wang, Qian

    2009-05-05

    An extensive study of the factors that affect the interfacial assembly of bionanoparticles at the oil/water (O/W) interface is reported. Bionanoparticles, such as viruses, have distinctive structural properties due to the unique arrangement of their protein structures. The assembly process of such bionanoparticles at interfaces is governed by factors including the ionic strength and pH of the aqueous layer, concentration of the particles, and nature of the oil phase. This study highlights the impact of these factors on the interfacial assembly of bionanoparticles at the O/W interface using native turnip yellow mosaic virus (TYMV) as the prototype. Robust monolayer assemblies of TYMV were produced by self-assembly at the O/W interface using emulsions and planar interfaces. TYMV maintained its structure and integrity under different assembly conditions. For the emulsion droplets, they were fully covered with TYMV as evidenced by transmission electron microscopy (TEM) and scanning force microscopy (SFM). Tensiometry and small-angle neutron scattering (SANS) further supported this finding. Although the emulsions offered a complete coverage by TYMV particles, they lacked long-range ordering due to rapid exchange at the interface. By altering the assembly process, highly ordered, hexagonal arrays of TYMV were obtained at planar O/W interfaces. The pH, ionic strength, and viscosity of the solution played a crucial role in enhancing the lateral ordering of TYMV assembled at the planar O/W interface. This interfacial ordering of TYMV particles was further stabilized by introduction of a positively charged dehydroabietyl amine (DHAA) in the organic phase which held the assembly together by electrostatic interactions. The long-range array formation was observed using TEM and SFM. The results presented here illustrate that the interfacial assembly at the O/W interface is a versatile approach to achieve highly stable self-assembled structures.

  6. Nanoscale and single-molecule interfacial electron transfer

    DEFF Research Database (Denmark)

    Hansen, Allan Glargaard; Wackerbarth, Hainer; Nielsen, Jens Ulrik

    2003-01-01

    Electrochemical science and technology in the 21st century have reached high levels of sophistication. A fundamental quantum mechanical theoretical frame for interfacial electrochemical electron transfer (ET) was introduced by Revaz Dogonadze. This frame has remained for four decades as a basis...... scanning tunneling microscopy (STM) and single-electron tunneling (SET, or Coulomb blockade) in electrochemical. systems directly in aqueous electrolyte solution and at room temperature. We illustrate the new theoretical formalism and its perspectives by recent cases of electrochemical SET, negative...

  7. International Symposium on Interfacial Joining and Surface Technology (IJST2013)

    Science.gov (United States)

    Takahashi, Yasuo

    2014-08-01

    Interfacial joining (bonding) is a widely accepted welding process and one of the environmentally benign technologies used in industrial production. As the bonding temperature is lower than the melting point of the parent materials, melting of the latter is kept to a minimum. The process can be based on diffusion bonding, pressure welding, friction welding, ultrasonic bonding, or brazing-soldering, all of which offer many advantages over fusion welding. In addition, surface technologies such as surface modification, spraying, coating, plating, and thin-film formation are necessary for advanced manufacturing, fabrication, and electronics packaging. Together, interfacial joining and surface technology (IJST) will continue to be used in various industrial fields because IJST is a very significant form of environmentally conscious materials processing. The international symposium of IJST 2013 was held at Icho Kaikan, Osaka University, Japan from 27-29 November, 2013. A total of 138 participants came from around the world to attend 56 oral presentations and 36 posters presented at the symposium, and to discuss the latest research and developments on interfacial joining and surface technologies. This symposium was also held to commemorate the 30th anniversary of the Technical Commission on Interfacial Joining of the Japan Welding Society. On behalf of the chair of the symposium, it is my great pleasure to present this volume of IOP Conference Series: Materials Science and Engineering (MSE). Among the presentations, 43 papers are published here, and I believe all of the papers have provided the welding community with much useful information. I would like to thank the authors for their enthusiastic and excellent contributions. Finally, I would like to thank all members of the committees, secretariats, participants, and everyone who contributed to this symposium through their support and invaluable effort for the success of IJST 2013. Yasuo Takahashi Chair of IJST 2013

  8. On the stabilization of viscoelastic laminated beams with interfacial slip

    Science.gov (United States)

    Mustafa, Muhammad I.

    2018-04-01

    In this paper, we consider a viscoelastic laminated beam model. This structure is given by two identical uniform layers on top of each other, taking into account that an adhesive of small thickness is bonding the two surfaces and produces an interfacial slip. We use viscoelastic damping with general assumptions on the relaxation function and establish explicit energy decay result from which we can recover the optimal exponential and polynomial rates. Our result generalizes the earlier related results in the literature.

  9. International Symposium on Interfacial Joining and Surface Technology (IJST2013)

    International Nuclear Information System (INIS)

    Takahashi, Yasuo

    2014-01-01

    Interfacial joining (bonding) is a widely accepted welding process and one of the environmentally benign technologies used in industrial production. As the bonding temperature is lower than the melting point of the parent materials, melting of the latter is kept to a minimum. The process can be based on diffusion bonding, pressure welding, friction welding, ultrasonic bonding, or brazing-soldering, all of which offer many advantages over fusion welding. In addition, surface technologies such as surface modification, spraying, coating, plating, and thin-film formation are necessary for advanced manufacturing, fabrication, and electronics packaging. Together, interfacial joining and surface technology (IJST) will continue to be used in various industrial fields because IJST is a very significant form of environmentally conscious materials processing. The international symposium of IJST 2013 was held at Icho Kaikan, Osaka University, Japan from 27–29 November, 2013. A total of 138 participants came from around the world to attend 56 oral presentations and 36 posters presented at the symposium, and to discuss the latest research and developments on interfacial joining and surface technologies. This symposium was also held to commemorate the 30th anniversary of the Technical Commission on Interfacial Joining of the Japan Welding Society. On behalf of the chair of the symposium, it is my great pleasure to present this volume of IOP Conference Series: Materials Science and Engineering (MSE). Among the presentations, 43 papers are published here, and I believe all of the papers have provided the welding community with much useful information. I would like to thank the authors for their enthusiastic and excellent contributions. Finally, I would like to thank all members of the committees, secretariats, participants, and everyone who contributed to this symposium through their support and invaluable effort for the success of IJST 2013. Yasuo Takahashi Chair of IJST 2013

  10. Study of microscale interfacial phenomena during phase change processes: Analysis of micro-drops and thin films

    Science.gov (United States)

    Gokhale, Shripad

    Interfacial phenomena in the three phase contact line region, where a liquid-vapor interface intersects a solid surface, are of importance to many phenomena such as contact angle, adsorption, surface patterning, spreading, thin film stability, phase change, etc. The objectives of this work are to experimentally analyze the coupled phenomena of spreading and phase change for a partially wetting system. We studied five experimental systems: S1---spreading of apolar n-butanol drops during phase change processes, S2 and S3---effects of surface modification on n-butanol spreading and dewetting of the meniscus, S4---spreading of polar 2-propanol drop, S5---coalescence of 2-propanol droplets, and S6---evaporation and spreading of surfactant laden micro-drops of water. Using system S1, we found that the interfacial velocity for the drop during condensation and evaporation is a function of the apparent contact angle and the rate of change of radius of curvature. Using systems S2 and S3, the vivid difference in the behavior of the retracting meniscus with respect to its variation in apparent contact angle and curvature was found to depend on the wettability. Using system S4, an improved image analyzing technique based on the reflectivity measurements using interferometry was developed, which gives fundamental insights about the physics of interfacial phenomena of a spreading drop during phase change. The reflectivity technique was also used in system S5 to study the shapes of condensing drops during their coalescence on the quartz surface. We found that the curvature and its gradient govern the growth and coalescence of the condensing drops. In system S6, the stability of the adsorbed film was analyzed using the concept of minimization of the interfacial free energy. During a phase change process, the thin film of the surfactant solution was unstable and it broke into micro-drops. The drop profiles were experimentally measured and analyzed during the phase change process as

  11. Tension-type headache: pain, fatigue, tension, and EMG responses to mental activation.

    Science.gov (United States)

    Bansevicius, D; Westgaard, R H; Sjaastad, O M

    1999-06-01

    Twenty patients with tension-type headache (14 chronic and 6 episodic) and 20 group-matched controls were selected for this study. They participated in a 1-hour, complex, two-choice, reaction-time test, as well as 5-minute pretest and 20-minute posttest periods. Subjects reported any pain in the forehead, temples, neck, and shoulders, as well as any feelings of fatigue and tension during the pretest, and every 10 minutes during the test and posttest by visual analog scales. Superficial electromyography was recorded simultaneously from positions representing the frontal and temporal muscles, neck (mostly splenius), and trapezius muscles. The location of pain corresponded to the position of the electrodes, but extended over a larger area. The test provoked pain in the forehead, neck, and shoulders of patients, i.e., pain scores from these regions increased significantly during the test. The pain scores continued to increase posttest. In patients, the EMG response of the trapezius (first 10 minutes of the test) was elevated relative to pretest. In controls, only the frontal muscles showed an EMG test response. Patients showed significantly higher EMG responses than controls in the neck (whole test period) and trapezius (first 10 minutes of the test period). There were significant differences in pain and fatigue scoring between patients and controls in all three periods and in tension scoring posttest. Fatigue correlated with pain, with increasing significance for all locations examined, while tension was mainly associated with the neck pain. The meaning of the variables "tension" and "fatigue" in headache, and their association with recorded muscle activity in various regions is discussed. The EMG response of the trapezius muscle to the test is discussed in comparison with similar responses observed in patients with other pain syndromes.

  12. Simulation studies of structure and edge tension of lipid bilayer edges: effects of tail structure and force-field.

    Science.gov (United States)

    West, Ana; Ma, Kevin; Chung, Jonathan L; Kindt, James T

    2013-08-15

    Molecular dynamics simulations of lipid bilayer ribbons have been performed to investigate the structures and line tensions associated with free bilayer edges. Simulations carried out for dioleoyl phosphatidylcholine with three different force-field parameter sets yielded edge line tensions of 45 ± 2 pN, over 50% greater than the most recently reported experimentally determined value for this lipid. Edge tensions obtained from simulations of a series of phosphatidylcholine lipid bilayer ribbons with saturated acyl tails of length 12-16 carbons and with monounsaturated acyl tails of length 14-18 carbons could be correlated with the excess area associated with forming the edge, through a two-parameter fit. Saturated-tail lipids underwent local thickening near the edge, producing denser packing that correlated with lower line tensions, while unsaturated-tail lipids showed little or no local thickening. In a dipalmitoyl phosphatidylcholine ribbon initiated in a tilted gel-phase structure, lipid headgroups tended to tilt toward the nearer edge producing a herringbone pattern, an accommodation that may account for the reported edge-induced stabilization of an ordered structure at temperatures near a lipid gel-fluid phase transition.

  13. Visualization of interfacial behavior of liquid jet in pool

    International Nuclear Information System (INIS)

    Uchiyama, Yuta; Abe, Yutaka; Fujiwara, Akiko; Nariai, Hideki; Matsuo, Eiji; Chitose, Keiko; Koyama, Kazuya; Itoh, Kazuhiro

    2008-01-01

    For the safety design of the Fast Breeder Reactor (FBR), it is strongly required that the post accident heat removal (PAHR) is achieved after a postulated core disruptive accident (CDA). In the PAHR, it is important that the molten core material is quenched (breakup) in sodium coolant. In the previous studies, it is pointed out that the jet breakup behavior is significantly influenced by the fragmentation behavior on the jet surface in the coolant. However, the process from interfacial instability to fragmentation on the jet surface to jet breakup is not elucidated in detail yet. In the present study, the jet breakup behavior is observed to obtain the fragmentation behavior on the jet surface in coolant in detail. The transparent fluid is used as the core material and is injected into the water as the coolant. The velocity distribution of internal flow of the jet is measured by PIV technique and shear stress is calculated from PIV results. From experimental results, unstable interfacial wave is confirmed as upstream and grown up toward downstream. The fragments are torn apart at the end of developed wave. Shear stress is strongly acted on jet surface. From the results, the correlation between the interfacial behavior of the jet and the generation process of fragments are discussed. (author)

  14. Interfacial self-healing of nanocomposite hydrogels: Theory and experiment

    Science.gov (United States)

    Wang, Qiming; Gao, Zheming; Yu, Kunhao

    2017-12-01

    Polymers with dynamic bonds are able to self-heal their fractured interfaces and restore the mechanical strengths. It is largely elusive how to analytically model this self-healing behavior to construct the mechanistic relationship between the self-healing properties (e.g., healed interfacial strength and equilibrium healing time) and the material compositions and healing conditions. Here, we take a self-healable nanocomposite hydrogel as an example to illustrate an interfacial self-healing theory for hydrogels with dynamic bonds. In the theory, we consider the free polymer chains diffuse across the interface and reform crosslinks to bridge the interface. We analytically reveal that the healed strengths of nanocomposite hydrogels increase with the healing time in an error-function-like form. The equilibrium self-healing time of the full-strength recovery decreases with the temperature and increases with the nanoparticle concentration. We further analytically reveal that the healed interfacial strength decreases with increasing delaying time before the healing process. The theoretical results quantitatively match with our experiments on nanosilica hydrogels, and also agree well with other researchers' experiments on nanoclay hydrogels. We expect that this theory would open promising avenues for quantitative understanding of the self-healing mechanics of various polymers with dynamic bonds, and offer insights for designing high-performance self-healing polymers.

  15. DNA Nanotechnology-Enabled Interfacial Engineering for Biosensor Development.

    Science.gov (United States)

    Ye, Dekai; Zuo, Xiaolei; Fan, Chunhai

    2018-02-28

    Biosensors represent biomimetic analytical tools for addressing increasing needs in medical diagnosis, environmental monitoring, security, and biodefense. Nevertheless, widespread real-world applications of biosensors remain challenging due to limitations of performance, including sensitivity, specificity, speed, and reproducibility. In this review, we present a DNA nanotechnology-enabled interfacial engineering approach for improving the performance of biosensors. We first introduce the main challenges of the biosensing interfaces, especially under the context of controlling the DNA interfacial assembly. We then summarize recent progress in DNA nanotechnology and efforts to harness DNA nanostructures to engineer various biological interfaces, with a particular focus on the use of framework nucleic acids. We also discuss the implementation of biosensors to detect physiologically relevant nucleic acids, proteins, small molecules, ions, and other biomarkers. This review highlights promising applications of DNA nanotechnology in interfacial engineering for biosensors and related areas. Expected final online publication date for the Annual Review of Analytical Chemistry Volume 11 is June 12, 2018. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

  16. Physicochemical properties and interfacial adaptation of root canal sealers.

    Science.gov (United States)

    Cañadas, Piedad S; Berástegui, Ester; Gaton-Hernández, Patrícia; Silva, Léa A B; Leite, Giselle A; Silva, Roberto S

    2014-01-01

    This study compared the physicochemical properties and interfacial adaptation to canal walls of Endo-CPM-Sealer, Sealapex and Activ GP with the well-established AH Plus sealer. The following analyses were performed: radiopacity, pH variation and solubility using samples of each material and scanning electron microscopy of root-filled bovine incisors to evaluate the interfacial adaptation. Data were analyzed by the parametric and no-parametric tests (α=0.05). All materials were in accordance with the ANSI/ADA requirements for radiopacity. Endo-CPM-Sealer presented the lowest radiopacity values and AH Plus was the most radiopaque sealer (p=0.0001). Except for ActiV GP, which was acidic, all other sealers had basic chemical nature and released hydroxyl ions. Regarding solubility, all materials met the ANSI/ADA recommendations, with no statistically significant difference between the sealers (p=0.0834). AH Plus presented the best adaptation to canal walls in the middle (p=0.0023) and apical (p=0.0012) thirds, while the sealers Activ GP and Endo-CPM-Sealer had poor adaptation to the canal walls. All sealers, except for ActiV GP, were alkaline and all of them fulfilled the ANSI/ADA requirements for radiopacity and solubility. Regarding the interfacial adaptation, AH Plus was superior to the others considering the adaptation to the bovine root canal walls.

  17. Analysis of interfacial curvature during drainage and imbibition

    Science.gov (United States)

    Armstrong, R. T.; Porter, M. L.; Wildenschild, D.

    2011-12-01

    Recent synchrotron-based tomographic data sets of oil-water drainage and imbibition scenarios have been analyzed to quantify phase saturations, interfacial curvature, and separate connected from disconnected fluid phases. This allows us to follow the drainage and imbibition processes in great detail, assess equilibrium states, and understand the effects of fluid phase disconnection and re-connection on the resulting capillary pressures and interfacial curvatures. This analysis also allows for estimating capillary pressure (Pc) based on calculated curvatures and comparison to Pc measured externally with a transducer. Results indicate good agreement between curvature-based and transducer-based measurements when the connected phase interfaces are considered. Curvature measurements show a strong dependence on whether an interface is formed by connected or disconnected phases. Assuming that at equilibrium curvature is constant, curvature differences between the connected and disconnected phase interfaces can be used as a metric to asses equilibrium. Over longer equilibration, the average curvature value, for all interfaces, approaches the average curvature value predicted by the pressure transducer. Overall, the results indicate good agreement between curvature -based and transducer-based Pc measurements and allow for a detailed assessment of interfacial curvature during drainage and imbibition.

  18. Interfacial Materials for Organic Solar Cells: Recent Advances and Perspectives.

    Science.gov (United States)

    Yin, Zhigang; Wei, Jiajun; Zheng, Qingdong

    2016-08-01

    Organic solar cells (OSCs) have shown great promise as low-cost photovoltaic devices for solar energy conversion over the past decade. Interfacial engineering provides a powerful strategy to enhance efficiency and stability of OSCs. With the rapid advances of interface layer materials and active layer materials, power conversion efficiencies (PCEs) of both single-junction and tandem OSCs have exceeded a landmark value of 10%. This review summarizes the latest advances in interfacial layers for single-junction and tandem OSCs. Electron or hole transporting materials, including metal oxides, polymers/small-molecules, metals and metal salts/complexes, carbon-based materials, organic-inorganic hybrids/composites, and other emerging materials, are systemically presented as cathode and anode interface layers for high performance OSCs. Meanwhile, incorporating these electron-transporting and hole-transporting layer materials as building blocks, a variety of interconnecting layers for conventional or inverted tandem OSCs are comprehensively discussed, along with their functions to bridge the difference between adjacent subcells. By analyzing the structure-property relationships of various interfacial materials, the important design rules for such materials towards high efficiency and stable OSCs are highlighted. Finally, we present a brief summary as well as some perspectives to help researchers understand the current challenges and opportunities in this emerging area of research.

  19. Interfacial fracture toughness of aged adhesive-dentin interfaces.

    Science.gov (United States)

    De Munck, Jan; Poitevin, André; Lührs, Anne-Katrin; Pongprueksa, Pong; Van Ende, Annelies; Van Landuyt, Kirsten L; Van Meerbeek, Bart

    2015-04-01

    To assess interfacial fracture toughness of different adhesive approaches and compare to a standard micro-tensile bond-strength (μTBS) test after 6 months water storage. Chevron-notched beam fracture toughness (CNB) was determined using a modified ISO 24370:2005 standard. Adhesive-dentin micro-specimens (1.0 mm × 1.0 mm × 8-10 mm) were stressed in tensile until failure to determine the micro-tensile bond strength (μTBS). The highest mean μTBS and interfacial fracture toughness were measured for the multi-step adhesives Clearfil SE Bond (Kuraray Noritake) and OptiBond FL (Kerr). While large differences were observed in the bond strength values (from 7.4 to 27.2 MPa) of the one-step self-etch adhesives tested, interfacial fracture toughness was less different (from 0.7 to 1.0 MPam(1/2)). The adhesive with the lowest mean toughness (All-bond Universal, Bisco) had however the highest Weibull reliability, which might be a better parameter in regard to more consistent clinical performance. The self-adhesive composite Vertise Flow (Kerr) scored significantly lower at all levels. Although the ranking of the adhesives tested using CNB and μTBS corresponded well, the outcome of CNB appeared more reliable and less variable. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  20. Recent advances in interfacial engineering of perovskite solar cells

    Science.gov (United States)

    Ye, Meidan; He, Chunfeng; Iocozzia, James; Liu, Xueqin; Cui, Xun; Meng, Xiangtong; Rager, Matthew; Hong, Xiaodan; Liu, Xiangyang; Lin, Zhiqun

    2017-09-01

    Due to recent developments, organometallic halide perovskite solar cells (PSCs) have attracted even greater interest owing to their impressive photovoltaic properties and simple device manufacturing processes with the potential for commercial applications. The power conversion efficiencies (PCEs) of PSCs have surged from 3.8% for methyl ammonium lead halide-sensitized liquid solar cells, CH3NH3PbX3 (X  =  Cl, Br, I), in 2009, to more than 22% for all-solid-state solar cells in 2016. Over the past few years, significant effort has been dedicated to realizing PSCs with even higher performance. In this review, recent advances in the interfacial engineering of PSCs are addressed. The specific strategies for the interfacial engineering of PSCs fall into two categories: (1) solvent treatment and additives to improve the light-harvesting capabilities of perovskite films, and (2) the incorporation of various functional materials at the interfaces between the active layers (e.g. electron transporting layer, perovskite layer, and hole transporting layer). This review aims to provide a comprehensive overview of strategies for the interfacial engineering of PSCs with potential benefits including enhanced light harvesting, improved charge separation and transport, improved device stability, and elimination of photocurrent hysteresis.

  1. Flexible tension sensor based on poly(l-lactic acid) film with coaxial structure

    Science.gov (United States)

    Yoshida, Mitsunobu; Onishi, Katsuki; Tanimoto, Kazuhiro; Nishikawa, Shigeo

    2017-10-01

    We have developed a tension sensor with a coaxial structure using a narrow slit ribbon made of a uniaxially stretched poly(l-lactic acid) (PLLA) film for application to a wearable device. The tension sensor is produced as follows. We used tinsel wire as the center conductor of the sensor. The tinsel wire consists of a yarn of synthetic fibers arranged at the center, with a spirally wound rolled copper foil ribbon on the side surface. Next, slit ribbons obtained from a uniaxially oriented film of PLLA are wound helically on the side surface of the center conductor in the direction of a left-handed screw, at an angle of 45° to the central axis. The rolled copper foil is used as an outer conductor and covers the yarn without a gap. The prototype of the fabricated tension sensor has good flexibility, since the sensor is in the form of a filament and consists of a highly flexible material. For the 1 mm tension sensor, it was found that for a tension of 1 N, a charge of 14 pC was output. It was also found that the sensor maintained its room-temperature sensitivity up to 60 °C. Compared with an existing coaxial line sensor using poly(vinylidene fluoride) (PVDF), the sensor using PLLA does not exhibit pyroelectricity, meaning that no undesirable voltage is generated when in contact with body heat, which is a significant advantage as wearable sensors. The result has demonstrated the potential application of the PLLA film to wearable devices for detecting heartbeat and respiration.

  2. Surface tension of mixtures of molecular fluids: Comparison between the experimental and theoretical study of CH{sub 4} + Kr, Kr + NO, and CH{sub 4} + NO

    Energy Technology Data Exchange (ETDEWEB)

    Calado, J.C.G.; Saramago, B.J.V. [Instituto Superior Tecnico, Lisbon (Portugal). Centro de Quimica Estrutural; Santos Mendonca, A.F.S. dos; Soares, V.A.M. [Univ. de Lisboa, Lisbon (Portugal). Centro de Ciencia e Tecnologia de Materiais

    1997-01-01

    The authors report a study of the surface tension of three binary liquid mixtures of molecular fluids. A microscopic mean field theory (MFT) has been used to calculate the theoretical results enabling the comparison with the experimental data. The mean field theory has been successfully used in the prediction of the surface properties of simple systems composed by quasi-spherical molecules. In the present study the MFT was able to reproduce the essential features of the interfacial properties of the systems CH{sub 4} + Kr, Kr + NO and CH{sub 4} + NO. The pure components were modeled by Lennard-Jones potentials with a set of intermolecular parameters taken from the literature for Kr and calculated from the fitting of the energy parameters to the surface tension, for CH{sub 4} and NO. In the case of the mixtures, it was found that reasonable agreement with experiment can only be obtained by allowing deviations from the Lorentz-Berthelot combining rules. For the CH{sub 4} + Kr system the authors used the binary energy parameter {xi} obtained through a fitting to the bulk properties; for the Kr + NO and CH{sub 4} + NO systems the binary parameter was adjusted to the interfacial properties.

  3. Surface Tension of Mixtures of Molecular Fluids: Comparison between the Experimental and Theoretical Study of CH4 + Kr, Kr + NO, and CH4 + NO

    Science.gov (United States)

    Calado; Mendonca; Saramago; Soares

    1997-01-01

    We report a study of the surface tension of three binary liquid mixtures of molecular fluids. A microscopic mean field theory (MFT) has been used to calculate the theoretical results enabling the comparison with the experimental data. The mean field theory has been successfully used in the prediction of the surface properties of simple systems composed by quasi-spherical molecules. In the present study the MFT was able to reproduce the essential features of the interfacial properties of the systems CH4 + Kr, Kr + NO and CH4 + NO. The pure components were modeled by Lennard-Jones potentials with a set of intermolecular parameters taken from the literature for Kr and calculated from the fitting of the energy parameters (epsilon) to the surface tension, for CH4 and NO. In the case of the mixtures, it was found that reasonable agreement with experiment can only be obtained by allowing deviations from the Lorentz-Berthelot combining rules. For the CH4 + Kr system we used the binary energy parameter xi obtained through a fitting to the bulk properties; for the Kr + NO and CH4 + NO systems the binary parameter was adjusted to the interfacial properties.

  4. Modification of Upper Thread Tensioner of Sewing Machine

    Science.gov (United States)

    Klouček, P.; Škop, P.

    Standard mechanical upper thread tensioner of sewing machines is more and more limited in use for industrial sewing machines due to increasing requests for quality and raising velocity of machines. If we omit mostly manual settings of force made only by sense, the most problematic things are influence of different friction coefficient of the different batch of threads and strong relation between thread tension and sewing machine velocity. The article describes the development focused to the elimination of the most significant disadvantages of a standard tensioner and mainly finding of new conception of the tensioner with electromagnetic brake, development and testing of its prototype.

  5. STRENGTH SHRINKAGE AND CREEP OF CONCRETE IN TENSION AND COMPRESSION

    Directory of Open Access Journals (Sweden)

    S A Kristiawan

    2006-01-01

    Full Text Available Strength, shrinkage and creep of concrete in tension and compression have been determined and the relationship between those properties was studied. Direct tensile tests were applied to measure those properties in tension. The relationship of creep in tension and compression was determined based on the measurement of creep at similar stress and similar stress/strength ratio. It is found that concrete deforms more in tension than in compression. Except for concrete with a higher water/cement ratio, the use of pulverised fuel ash, ground granulated blast furnace slag, superplasticizer and shrinkage reducing admixture has no effect on strength. However, they affect creep and shrinkage of concrete.

  6. Bending Under Tension Test with Direct Friction Measurement

    DEFF Research Database (Denmark)

    Andreasen, Jan Lasson; Olsson, David Dam; Chodnikiewicz, K.

    2006-01-01

    A special Bending-Under-Tension (BUT) transducer has been developed in which friction around the tool radius can be directly measured when drawing a plane sheet strip around a cylindrical tool-pin under constant back tension. The front tension, back tension and torque on the tool-pin are all...... measured directly, thus enabling accurate measurement of friction and direct determination of lubricant film breakdown for varying normal pressure, sliding speed, tool radius and tool preheat temperature. The transducer is applied in an experimental investigation focusing on limits of lubrication...... in drawing of stainless steel showing the influence of varying process conditions and the performance of different lubricants....

  7. Preparation of Pickering emulsions through interfacial adsorption by soft cyclodextrin nanogels

    Directory of Open Access Journals (Sweden)

    Shintaro Kawano

    2015-11-01

    Full Text Available Background: Emulsions stabilized by colloidal particles are known as Pickering emulsions. To date, soft microgel particles as well as inorganic and organic particles have been utilized as Pickering emulsifiers. Although cyclodextrin (CD works as an attractive emulsion stabilizer through the formation of a CD–oil complex at the oil–water interface, a high concentration of CD is normally required. Our research focuses on an effective Pickering emulsifier based on a soft colloidal CD polymer (CD nanogel with a unique surface-active property.Results: CD nanogels were prepared by crosslinking heptakis(2,6-di-O-methyl-β-cyclodextrin with phenyl diisocyanate and subsequent immersion of the resulting polymer in water. A dynamic light scattering study shows that primary CD nanogels with 30–50 nm diameter assemble into larger CD nanogels with 120 nm diameter by an increase in the concentration of CD nanogel from 0.01 to 0.1 wt %. The CD nanogel has a surface-active property at the air–water interface, which reduces the surface tension of water. The CD nanogel works as an effective Pickering emulsion stabilizer even at a low concentration (0.1 wt %, forming stable oil-in-water emulsions through interfacial adsorption by the CD nanogels.Conclusion: Soft CD nanogel particles adsorb at the oil–water interface with an effective coverage by forming a strong interconnected network and form a stable Pickering emulsion. The adsorption property of CD nanogels on the droplet surface has great potential to become new microcapsule building blocks with porous surfaces. These microcapsules may act as stimuli-responsive nanocarriers and nanocontainers.

  8. Temperature anisotropy at equilibrium reveals nonlocal entropic contributions to interfacial properties

    Science.gov (United States)

    Wilhelmsen, Øivind; Trinh, Thuat T.; Lervik, Anders

    2018-01-01

    Density gradient theory for fluids has played a key role in the study of interfacial phenomena for a century. In this work, we revisit its fundamentals by examining the vapor-liquid interface of argon, represented by the cut and shifted Lennard-Jones fluid. The starting point has traditionally been a Helmholtz energy functional using mass densities as arguments. By using rather the internal energy as starting point and including the entropy density as an additional argument, following thereby the phenomenological approach from classical thermodynamics, the extended theory suggests that the configurational part of the temperature has different contributions from the parallel and perpendicular directions at the interface, even at equilibrium. We find a similar anisotropy by examining the configurational temperature in molecular dynamics simulations and obtain a qualitative agreement between theory and simulations. The extended theory shows that the temperature anisotropy originates in nonlocal entropic contributions, which are currently missing from the classical theory. The nonlocal entropic contributions discussed in this work are likely to play a role in the description of both equilibrium and nonequilibrium properties of interfaces. At equilibrium, they influence the temperature- and curvature-dependence of the surface tension. Across the vapor-liquid interface of the Lennard Jones fluid, we find that the maximum in the temperature anisotropy coincides precisely with the maximum in the thermal resistivity relative to the equimolar surface, where the integral of the thermal resistivity gives the Kapitza resistance. This links the temperature anisotropy at equilibrium to the Kapitza resistance of the vapor-liquid interface at nonequilibrium.

  9. Neurotrophic factors in tension-type headache

    Directory of Open Access Journals (Sweden)

    Renan B. Domingues

    2015-05-01

    Full Text Available Neurotrophic factors (NF are involved in pain regulation and a few studies have suggested that they may play a pathophysiological role in primary headaches. The aim of this study was to investigate NF levels in patients with tension type headache (TTH. We carried out a cross sectional study including 48 TTH patients and 48 age and gender matched controls. Beck Depression and Anxiety Inventories, and Headache Impact Test were recorded. Serum levels of NF were determined by ELISA. There were not significant differences between NF levels between TTH patients and controls. Patients with chronic and episodic TTH had not significant differences in NF levels. The presence of headache at the time of evaluation did not significantly alter the levels of NF. Depression and anxiety scores as well as headache impact did not correlate with NF levels. Our study suggest that the serum levels of NF are not altered in TTH.

  10. Cognitive functions and normal tension glaucoma.

    Science.gov (United States)

    Daveckaite, Akvile; Grusauskiene, Evelina; Petrikonis, Kestutis; Vaitkus, Antanas; Siaudvytyte, Lina; Januleviciene, Ingrida

    2017-10-01

    Only a few studies have analyzed the potential link between glaucoma and cognitive function impairment. They have found controversial results. This study aims to perform quick cognitive function assessment with clock drawing test (CDT) using two different scoring systems and compare between normal tension glaucoma (NTG) and cataract patients. Totally, 30 NTG and 30 patients with cataracts were included in a prospective, pilot study. The predrawn circle was given, and patients were asked to draw the clock showing a time of 11:10. The test was evaluated using two methods - Freund method using a 7-point scoring scale (optimal cutoff ≤4) and Rakusa using a 4-point scoring scale (optimal cutoff ≤3). The level of significance was set at P drawing. Further prospective studies are needed to investigate the CDT reliability as fast screening test of cognitive function impairment in glaucoma patients.

  11. Evolving spacetimes with purely radial tension

    Directory of Open Access Journals (Sweden)

    B. Nasre Esfahani

    2000-12-01

    Full Text Available   In this study time-dependent and spherically symmetric solutions of the Einstein field equations in an anisotropic background with a purely radial tension are presented. There exist three classes of solutions,1 An open spacetime with a wormhole at its center. 2 A conical spacetime. 3 A closed spacetime. These inhomogeneous solutions are reduced to FRW spacetimes in matter-dominated era, asymptotically. Therefore, they can be used to describe local inhomogeneities that are not considered in the standard model. For the wormhole solution. it is explicity shown that the considered matter is non-exotic, that is, it does not violate the energy conditions. Also, static solutions are studied. There is only one static solution,a conical spacetime. In this case, the matter satisfies the energy condition critically.

  12. Biaxial tension on polymer in thermoforming range

    Directory of Open Access Journals (Sweden)

    Billon N.

    2010-06-01

    Full Text Available This paper presents an experimental characterization of mechanical properties of a polyethylene terephtalate (PET resin classically used in stretch blow moulding process. We have applied on such a material a well established experimental protocol at CEMEF, including new and relevant biaxial tensile tests. The experimental set-up relative to biaxial tension will be presented and described in a first part of the paper. Furthermore, we will focus on the experimental DMTA preliminary tests which are required to estimate the resin sensibility to temperature and strain rate in linear viscoelasticity domain. Finally, we will be interested in the material large strain behaviour: biaxial tensile results are presented and discussed. Finally, such an experimental approach should allow a relevant modelling of polymer physics and mechanics; this point will not be discussed here because of a lack of time.

  13. Damage development in woven fabric composites during tension-tension fatigue

    DEFF Research Database (Denmark)

    Hansen, U.

    1999-01-01

    of the operating fatigue damage mechanism(s). Fatigue leads to a degradation of material properties. Consequently, in connection with impact induced local stress raisers, fatigue produces continuously changing non-uniform stress fields because of stress redistribution effects. Other models addressing evolution......Impacted woven fabric composites were tested in tension-tension fatigue. In contrast to results from static testing, the effects of low energy impact damage in a fatigue environment were found to be the critical element leading to failure of the specimen. This difference emphasizes the need...... to identify and understand the fatigue damage mechanism. A relatively new non-destructive inspection technique using infrared thermography was found to be a very useful tool in detecting damage initiation and growth. Furthermore, this technique supplies valuable information to the characterization...

  14. Urinary incontinence - tension-free vaginal tape

    Science.gov (United States)

    ... pubic hair line. A special man-made (synthetic mesh) tape is passed through the cut inside the ... West Bloomfield, MI. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical ...

  15. pH-Induced Changes in the Surface Viscosity of Unsaturated Phospholipids Monitored Using Active Interfacial Microrheology.

    Science.gov (United States)

    Ghazvini, Saba; Alonso, Ryan; Alhakamy, Nabil; Dhar, Prajnaparamita

    2018-01-23

    Lipid membranes, a major component of cells, are subjected to significant changes in pH depending on their location in the cell: the outer leaflet of the cell membrane is exposed to a pH of 7.4 whereas lipid membranes that make up late endosomes and lysosomes are exposed to a pH of as low as 4.4. The purpose of this study is to evaluate how changes in the environmental pH within cells alter the fluidity of phospholipid membranes. Specifically, we studied pH-induced alterations in the surface arrangement of monounsaturated lipids with zwitterionic headgroups (phosphoethanolamine (PE) and phosphocholine (PC)) that are abundant in plasma membranes as well as anionic lipids (phosphatidylserine (PS) and phosphatidylglycerol (PG)) that are abundant in inner membranes using a combination of techniques including surface tension vs area measurements, interfacial microrheology, and fluorescence/atomic force microscopy. Using an active interfacial microrheology technique, we find that phospholipids with zwitterionic headgroups show a significant increase in their surface viscosity at acidic pH. This increase in surface viscosity is also found to depend on the size of the lipid headgroup, with a smaller headgroup showing a greater increase in viscosity. The observed pH-induced increase in viscosity is also accompanied by an increase in the cohesion pressure between zwitterionic molecules at acidic pH and a decrease in the average molecular area of the lipids, as measured by fitting the surface pressure isotherms to well-established equations of state. Because fluorescent images show no change in the phase of the lipids, we attribute this change in surface viscosity to the pH-induced reorientation of the P - -N + dipoles that form part of the polar lipid headgroup, resulting in increased lipid-lipid interactions. Anionic PG headgroups do not demonstrate this pH-induced change in viscosity, suggesting that the presence of a net negative charge on the headgroup causes

  16. The Effect of Surface Tension on the Gravity-driven Thin Film Flow of Newtonian and Power-law Fluids.

    Science.gov (United States)

    Hu, Bin; Kieweg, Sarah L

    2012-07-15

    Gravity-driven thin film flow is of importance in many fields, as well as for the design of polymeric drug delivery vehicles, such as anti-HIV topical microbicides. There have been many prior works on gravity-driven thin films. However, the incorporation of surface tension effect has not been well studied for non-Newtonian fluids. After surface tension effect was incorporated into our 2D (i.e. 1D spreading) power-law model, we found that surface tension effect not only impacted the spreading speed of the microbicide gel, but also had an influence on the shape of the 2D spreading profile. We observed a capillary ridge at the front of the fluid bolus. Previous literature shows that the emergence of a capillary ridge is strongly related to the contact line fingering instability. Fingering instabilities during epithelial coating may change the microbicide gel distribution and therefore impact how well it can protect the epithelium. In this study, we focused on the capillary ridge in 2D flow and performed a series of simulations and showed how the capillary ridge height varies with other parameters, such as surface tension coefficient, inclination angle, initial thickness, and power-law parameters. As shown in our results, we found that capillary ridge height increased with higher surface tension, steeper inclination angle, bigger initial thickness, and more Newtonian fluids. This study provides the initial insights of how to optimize the flow and prevent the appearance of a capillary ridge and fingering instability.

  17. The Effect of Surface Tension on the Gravity-driven Thin Film Flow of Newtonian and Power-law Fluids

    Science.gov (United States)

    Hu, Bin; Kieweg, Sarah L.

    2012-01-01

    Gravity-driven thin film flow is of importance in many fields, as well as for the design of polymeric drug delivery vehicles, such as anti-HIV topical microbicides. There have been many prior works on gravity-driven thin films. However, the incorporation of surface tension effect has not been well studied for non-Newtonian fluids. After surface tension effect was incorporated into our 2D (i.e. 1D spreading) power-law model, we found that surface tension effect not only impacted the spreading speed of the microbicide gel, but also had an influence on the shape of the 2D spreading profile. We observed a capillary ridge at the front of the fluid bolus. Previous literature shows that the emergence of a capillary ridge is strongly related to the contact line fingering instability. Fingering instabilities during epithelial coating may change the microbicide gel distribution and therefore impact how well it can protect the epithelium. In this study, we focused on the capillary ridge in 2D flow and performed a series of simulations and showed how the capillary ridge height varies with other parameters, such as surface tension coefficient, inclination angle, initial thickness, and power-law parameters. As shown in our results, we found that capillary ridge height increased with higher surface tension, steeper inclination angle, bigger initial thickness, and more Newtonian fluids. This study provides the initial insights of how to optimize the flow and prevent the appearance of a capillary ridge and fingering instability. PMID:23687391

  18. A Novel Model of Dielectric Constant of Two-Phase Composites with Interfacial Shells

    Science.gov (United States)

    Xue, Qingzhong

    Considering the interface effect between two phases in composite, we present a novel model of dielectric constant of two-phase composites with interfacial shells. Starting from Maxwell theory and average polarization theory, the formula of calculating the effective dielectric constant of two-phase random composites with interfacial shells is presented. The theoretical results on effective dielectric constant of alkyd resin paint/Barium titanate random composites with interfacial shells are in good agreement with the experimental data.

  19. Interfacial rheology of fluid/fluid systems. Study of model hydrocarbon-water-surfactant systems.

    OpenAIRE

    Zanobini, Alessandra; Santini, Eva; Ravera, Francesca; Pandolfini, Piero; Noskov, Boris A.; Miller, Reinhard; Makievski, Alexander V.; Loglio, Giuseppe; Liggieri, Libero; Kr?gel, J?rgen; Ferrari, Michele; Del Gaudio, Lucilla

    2006-01-01

    Crude-oil technology specifically involves the application of interfacial rheological properties. Actually, static and dynamic interfacial physical quantities encompass several processes of interest for oil industry (such as enhanced oil recovery, emulsion formation, emulsion-stability control and breaking, oil de-watering, emulsion/sludge separation in waste water treatment, et cetera). Three points are worth to be taken into consideration. A) The role of interfacial viscoelasticity of dropl...

  20. Corrosion resistance of grouted post-tensioning systems : [summary].

    Science.gov (United States)

    2013-08-01

    The increased popularity of post-tensioned bridge construction in the United States has led to concerns about corrosion and its impact on the life cycle of these bridges. Although the vast majority of post-tensioned bridges in the United States have ...

  1. Rapid cable tension estimation using dynamic and mechanical properties

    Science.gov (United States)

    Martínez-Castro, Rosana E.; Jang, Shinae; Christenson, Richard E.

    2016-04-01

    Main tension elements are critical to the overall stability of cable-supported bridges. A dependable and rapid determination of cable tension is desired to assess the state of a cable-supported bridge and evaluate its operability. A portable smart sensor setup is presented to reduce post-processing time and deployment complexity while reliably determining cable tension using dynamic characteristics extracted from spectral analysis. A self-recording accelerometer is coupled with a single-board microcomputer that communicates wirelessly with a remote host computer. The portable smart sensing device is designed such that additional algorithms, sensors and controlling devices for various monitoring applications can be installed and operated for additional structural assessment. The tension-estimating algorithms are based on taut string theory and expand to consider bending stiffness. The successful combination of cable properties allows the use of a cable's dynamic behavior to determine tension force. The tension-estimating algorithms are experimentally validated on a through-arch steel bridge subject to ambient vibration induced by passing traffic. The tension estimation is determined in well agreement with previously determined tension values for the structure.

  2. Tension band wiring fi xation is associated with good functional ...

    African Journals Online (AJOL)

    Background: Tension band wiring (TBW) is a widely accepted technique for olecranon fractures. Various investigators have reported a significant rate of complications especially hardware prominence. The purpose of this study was to determine the clinical and radiological outcome after tension band wiring of olecranon ...

  3. College Learning and Teaching: Struggling with/in the Tensions.

    Science.gov (United States)

    Child, Mark; Williams, David D.

    1996-01-01

    Tensions arising in the college classroom when a teacher attempts to change instructional practice and meets resistance are examined. It is suggested that the common response is for both teacher and students to struggle to overcome tensions entirely, which tends to reproduce the original instructional problems. Alternative approaches that can…

  4. Tensions within Teaching: An Autoethnography of an American Teacher

    Science.gov (United States)

    Tuura, Brianne Marie

    2012-01-01

    This dissertation examines the personal transformation of an American teacher as she becomes aware of the social, political, and economic tensions that exist within the American school system and the affects these tensions have on her ability to teach. As the researcher becomes more aware of power structures surrounding her, the reader is enabled…

  5. Surface tension of ionic liquids and ionic liquid solutions.

    Science.gov (United States)

    Tariq, Mohammad; Freire, Mara G; Saramago, Benilde; Coutinho, João A P; Lopes, José N Canongia; Rebelo, Luís Paulo N

    2012-01-21

    Some of the most active scientific research fronts of the past decade are centered on ionic liquids. These fluids present characteristic surface behavior and distinctive trends of their surface tension versus temperature. One way to explore and understand their unique nature is to study their surface properties. This critical review analyses most of the surface tension data reported between 2001 and 2010 (187 references).

  6. Creative tensions in youth ministry in a congregational context ...

    African Journals Online (AJOL)

    congregational approach to youth ministry could lead to certain creative tensions in youth ministry as an integral part of congregational ministry. Therefore the article identifies and discusses specific creative tensions that could be present in youth ministry where the inclusive congregational approach to youth ministry is ...

  7. Managing Tensions Between New and Existing Business Models

    DEFF Research Database (Denmark)

    Sund, Kristian J.; Bogers, Marcel; Villarroel, J. Andrei

    2016-01-01

    The search for new business models forces established companies to experiment with organizational designs — and leads to tensions that should be anticipated and carefully managed.......The search for new business models forces established companies to experiment with organizational designs — and leads to tensions that should be anticipated and carefully managed....

  8. Conducting Qualitative Data Analysis: Managing Dynamic Tensions within

    Science.gov (United States)

    Chenail, Ronald J.

    2012-01-01

    In the third of a series of "how-to" essays on conducting qualitative data analysis, Ron Chenail examines the dynamic tensions within the process of qualitative data analysis that qualitative researchers must manage in order to produce credible and creative results. These tensions include (a) the qualities of the data and the qualitative data…

  9. The Tension between Justice and Freedom in Paulo Freire's Epistemology.

    Science.gov (United States)

    Joldersma, Clarence W.

    2001-01-01

    Explores how the concept of freedom in Paulo Freire's constructivist epistemology-constituted as agentive, spontaneity-based action-is in tension with his ethical project of a pedagogy for justice, one based on responsibility and non-indifference. Resolution of this tension means reconceptualizing the grounding notion of the subject beyond a…

  10. Location and tension of the medial palpebral ligament.

    Science.gov (United States)

    Hwang, Kun; Huan, Fan; Nam, Yong Seok; Han, Seung Ho; Kim, Dae Joong

    2013-11-01

    The aim of this study was to elucidate the precise anatomic location and tension of the medial palpebral ligament (MPL). Eleven hemifaces of 10 fresh Korean adult cadavers were used in this study. Nine specimens were used for measurement of dissection and tension, and 2 were used for histologic study. Measurements of tensile strength of each part of the MPL and Horner muscle were performed using a force gauge.The MPL consisted of 2 layers in all specimens dissected. The superficial layer of the palpebral ligament (SMPL) was observed from the anterior lacrimal crest to the upper and lower tarsal plates. The deep layer of the palpebral ligament (DMPL) lay from the anterior lacrimal crest to the posterior lacrimal crest, covering the lacrimal sac. The Horner muscle was observed at the posterior lacrimal crest just lateral to the attachment of the DMPL and ran laterally to the tarsal plate deep to the SMPL. The SMPL began at 4.5 ± 2.3 mm lateral to the nasomaxillary suture line to the upper and lower tarsal plates. Its transverse length was 9.6 ± 1.5 mm, and vertical width was 2.4 ± 0.7 mm, and its thickness was 4.5 ± 2.3 mm. The transverse length of the DMPL was 3.7 ± 0.4 mm, and its vertical width was 2.9 ± 1.3 mm, with a thickness of 0.3 ± 0.1 mm. The transverse length of the Horner muscle was 7.6 ± 1.9 mm, and its vertical width was 4.06 ± 1.5 mm, with a thickness of 0.4 ± 0.1 mm. The tensile strength of the SMPL was 13.4 ± 3.2 N, that of the DMPL was 4.1 ± 1.7 N, and that for Horner muscle was 9.0 ± 3.1 N. The tensile strength of the SMPL was significantly higher than that of the DMPL (P = 0.003).We reconfirmed that the MPL consisted of 2 layers: superficial layer and deep layer. Our results might be of use in surgeries of the medial canthi.

  11. A method for volumetric retinal tissue oxygen tension imaging.

    Science.gov (United States)

    Felder, Anthony E; Wanek, Justin; Teng, Pang-Yu; Blair, Norman P; Shahidi, Mahnaz

    2018-01-01

    Inadequate retinal oxygenation occurs in many vision-threatening retinal diseases, including diabetic retinopathy, retinal vascular occlusions, and age-related macular degeneration. Therefore, techniques that assess retinal oxygenation are necessary to understand retinal physiology in health and disease. The purpose of the current study is to report a method for the three-dimensional (3D) imaging of retinal tissue oxygen tension (tPO 2 ) in rats. Imaging was performed in Long Evans pigmented rats under systemic normoxia (N = 6) or hypoxia (N = 3). A vertical laser line was horizontally scanned on the retina and a series of optical section phase-delayed phosphorescence images were acquired. From these images, phosphorescence volumes at each phase delay were constructed and a 3D retinal tPO 2 volume was generated. Retinal tPO 2 volumes were quantitatively analyzed by generating retinal depth profiles of mean tPO 2 (M tPO2 ) and the spatial variation of tPO 2 (SV tPO2 ). The effects of systemic condition (normoxia/hypoxia) and retinal depth on M tPO2 and SV tPO2 were determined by mixed linear model. Each 3D retinal tPO 2 volume was approximately 500 × 750 × 200 μm (horizontal × vertical × depth) and consisted of 45 en face tPO 2 images through the retinal depth. M tPO2 at the chorioretinal interface was significantly correlated with systemic arterial oxygen tension (P = 0.007; N = 9). There were significant effects of both systemic condition and retinal depth on M tPO2 and SV tPO2 , such that both were lower under hypoxia than normoxia and higher in the outer retina than inner retina (P < 0.001). For the first time, 3D imaging of retinal tPO 2 was demonstrated, with potential future application for assessment of physiological alterations in animal models of retinal diseases.

  12. The Integrity of ACSR Full Tension Single-Stage Splice Connector at Higher Operation Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [ORNL; Lara-Curzio, Edgar [ORNL; King Jr, Thomas J [ORNL

    2008-10-01

    Due to increases in power demand and limited investment in new infrastructure, existing overhead power transmission lines often need to operate at temperatures higher than those used for the original design criteria. This has led to the accelerated aging and degradation of splice connectors. It is manifested by the formation of hot-spots that have been revealed by infrared imaging during inspection. The implications of connector aging is two-fold: (1) significant increases in resistivity of the splice connector (i.e., less efficient transmission of electricity) and (2) significant reductions in the connector clamping strength, which could ultimately result in separation of the power transmission line at the joint. Therefore, the splice connector appears to be the weakest link in electric power transmission lines. This report presents a protocol for integrating analytical and experimental approaches to evaluate the integrity of full tension single-stage splice connector assemblies and the associated effective lifetime at high operating temperature.

  13. Enhancing the Interfacial and Dynamic Failure Behavior of Advanced Hybrid Structures Using Nanocomposite Materials

    National Research Council Canada - National Science Library

    Xu, Luoyu R

    2007-01-01

    .... The proposed design, inspired by the shape and mechanics of trees, effectively removed the stress singularity at the interfacial joint for most engineering materials through an integrated theoretical...

  14. High Line

    DEFF Research Database (Denmark)

    Kiib, Hans

    2015-01-01

    . The High Line project has been carried out as part of an open conversion strategy. The result is a remarkable urban architectural project, which works as a catalyst for the urban development of Western Manhattan. The greater project includes the restoration and reuse of many old industrial buildings......At just over 10 meters above street level, the High Line extends three kilometers through three districts of Southwestern Manhattan in New York. It consists of simple steel construction, and previously served as an elevated rail line connection between Penn Station on 34th Street and the many...... in close proximity to the park bridge and new projects being added to fit the context. The outcome is a conglomeration of non-contemporary urban activities along the High Line, where mechanical workshops, small wholesale stores. etc. mix with new exclusive residential buildings, eminent cafés...

  15. Myosin II dynamics are regulated by tension in intercalating cells.

    Science.gov (United States)

    Fernandez-Gonzalez, Rodrigo; Simoes, Sérgio de Matos; Röper, Jens-Christian; Eaton, Suzanne; Zallen, Jennifer A

    2009-11-01

    Axis elongation in Drosophila occurs through polarized cell rearrangements driven by actomyosin contractility. Myosin II promotes neighbor exchange through the contraction of single cell boundaries, while the contraction of myosin II structures spanning multiple pairs of cells leads to rosette formation. Here we show that multicellular actomyosin cables form at a higher frequency than expected by chance, indicating that cable assembly is an active process. Multicellular cables are sites of increased mechanical tension as measured by laser ablation. Fluorescence recovery after photobleaching experiments show that myosin II is stabilized at the cortex in regions of increased tension. Myosin II is recruited in response to an ectopic force and relieving tension leads to a rapid loss of myosin, indicating that tension is necessary and sufficient for cortical myosin localization. These results demonstrate that myosin II dynamics are regulated by tension in a positive feedback loop that leads to multicellular actomyosin cable formation and efficient tissue elongation.

  16. Planck and the local Universe: quantifying the tension

    CERN Document Server

    Verde, Licia; Protopapas, Pavlos

    2013-01-01

    We use the latest Planck constraints, and in particular constraints on the derived parameters (Hubble constant and age of the Universe) for the local universe and compare them with local measurements of the same quantities. We propose a way to quantify whether cosmological parameters constraints from two different experiments are in tension or not. Our statistic, T, is an evidence ratio and therefore can be interpreted with the widely used Jeffrey's scale. We find that in the framework of the LCDM model, the Planck inferred two dimensional, joint, posterior distribution for the Hubble constant and age of the Universe is in "strong" tension with the local measurements; the odds being ~ 1:50. We explore several possibilities for explaining this tension and examine the consequences both in terms of unknown errors and deviations from the LCDM model. In some one-parameter LCDM model extensions, tension is reduced whereas in other extensions, tension is instead increased. In particular, small total neutrino masses ...

  17. Maximizing aesthetics in lateral-tension abdominoplasty and body lifts.

    Science.gov (United States)

    Lockwood, Ted E

    2004-10-01

    The high-lateral-tension abdominoplasty addresses the practical and theoretic faults of standard abdominoplasty design. Key features include limited direct undermining, increased lateral skin resection with highest-tension wound closure along lateral limbs, two-layer superficial fascial system repair, and significant truncal liposuction when needed. The high-lateral-tension design limits the unfavorable features of standard abdominoplasty and produces balanced natural aesthetic contours. The high-lateral-tension abdominoplasty is the foundation for treatment of more generalized relaxation problems in the circumferential trunk and thighs. For more significant thigh laxity and buttock ptosis, the lateral-tension abdominoplasty is combined with the transverse thigh/buttock lift to produce the lower body lift #2.

  18. Exploratory experimental investigations on post-tensioned structural glass beams

    Directory of Open Access Journals (Sweden)

    Christian Louter

    2015-05-01

    Full Text Available The mechanical response of post-tensioned glass beams is explored in this paper. This is done through bending experiments on post-tensioned glass beam specimens with either mechanically anchored or adhesively bonded steel tendons by which a beneficial pre-stress is inflicted on the glass beams. In addition, reference beams with identical geometry but without tendons are tested. From the results of the bending experiments it can be seen that the post-tensioned glass beams reach higher initial fracture loads than the reference glass beams. Furthermore, the post-tensioned glass beams develop a significant post-fracture reserve. From this it is concluded that post-tensioning a glass beam is a feasible concept, which provides increased initial fracture strength and enhanced post-fracture performance.

  19. World lines.

    OpenAIRE

    Waser Jürgen; Fuchs Raphael; Ribicic Hrvoje; Schindler Benjamin; Blöschl Günther; Gröller Eduard

    2010-01-01

    In this paper we present World Lines as a novel interactive visualization that provides complete control over multiple heterogeneous simulation runs. In many application areas decisions can only be made by exploring alternative scenarios. The goal of the suggested approach is to support users in this decision making process. In this setting the data domain is extended to a set of alternative worlds where only one outcome will actually happen. World Lines integrate simulation visualization and...

  20. Interfacial Structural Transition in Hydration Shells of a Polarizable Solute.

    Science.gov (United States)

    Dinpajooh, Mohammadhasan; Matyushov, Dmitry V

    2015-05-22

    Electrostatics of polar solvation is typically described by harmonic free energy functionals. Polarizability contributes a negative polarization term that can make the harmonic free energy negative. The harmonic truncation fails in this regime. Simulations of polarizable ideal dipoles in water show that water's susceptibility passes through a maximum in the range of polarizabilities zeroing the harmonic term out. The microscopic origin of the nonmonotonic behavior is an interfacial structural transition involving the density collapse of the first hydration layer and enhanced number of dangling OH bonds.

  1. Interfacial area measurements in two-phase flow

    International Nuclear Information System (INIS)

    Veteau, J.-M.

    1979-08-01

    A thorough understanding of two-phase flow requires the accurate measurement of the time-averaged interfacial area per unit volume (also called the time-averaged integral specific area). The so-called 'specific area' can be estimated by several techniques described in the literature. These different methods are reviewed and the flow conditions which lead to a rigourous determination of the time-averaged integral specific area are clearly established. The probe technique, involving local measurements seems very attractive because of its large range of application [fr

  2. Estimated effects of interfacial vaporization on fission product scrubbing

    International Nuclear Information System (INIS)

    Moody, F.J.; Nagy, S.G.

    1983-01-01

    When bubbles containing non-condensible gas rise through a water pool, interfacial evaporation causes a flow of vapor into the bubbles. The inflow reduces the outward particle motion toward the bubble wall, diminishing the effectiveness of fission product particle removal. This analysis provides an estimate of evaporation on pool scrubbing effectiveness. It is shown that hot gas, which boils water at the bubble wall, reduces the effective scrubbing height by less than five centimeters. Although the evaporative humidification in a rising bubble containing non-condensible gas has a diminishing effect on scrubbing mechanisms, substantial decontamination is still expected even for the limiting case of a saturated pool

  3. POROUS MICROSTRUCTURE OF THE INTERFACIAL TRANSITION ZONE IN GEOPOLYMER COMPOSITES

    Directory of Open Access Journals (Sweden)

    Steinerová M.

    2013-12-01

    Full Text Available The study deals with a comparison of the differences in the structure, composition and micromechanical properties of a metakaolinite geopolymer composite matrix, inside and outside of the interfacial transition zone (ITZ with quartz grains of added silica sand. The microstructure is investigated by a measurement of the mercury porosimetry, microscopy and by a measurement in SEM and AFM, completed by Raman spectroscopy. Weaker mechanical properties, micropores in the ITZ, a higher concentration of Al atoms and hydroxyl groups than in the ambient matrix were detected. The water transport is probably the reason for the micropore formation, caused by disequilibrium in the course of solid-phase building from geopolymer dispersion.

  4. Exploiting interfacial water properties for desalination and purification applications.

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hongwu (Los Alamos National Laboratory, Los Alamos, NM); Varma, Sameer; Nyman, May Devan; Alam, Todd Michael; Thuermer, Konrad; Holland, Gregory P.; Leung, Kevin; Liu, Nanguo (University of New Mexico Albuquerque, NM); Xomeritakis, George K. (University of New Mexico Albuquerque, NM); Frankamp, Benjamin L.; Siepmann, J. Ilja (University of Minnesota, Minneapolis, MN); Cygan, Randall Timothy; Hartl, Monika A. (Los Alamos National Laboratory, Los Alamos, NM); Travesset, Alex (Iowa State University, Ames, IA); Anderson, Joshua A. (Iowa State University, Ames, IA); Huber, Dale L.; Kissel, David J. (University of New Mexico Albuquerque, NM); Bunker, Bruce Conrad; Lorenz, Christian Douglas; Major, Ryan C. (University of Minnesota, Minneapolis, MN); McGrath, Matthew J. (University of Minnesota, Minneapolis, MN); Farrow, Darcie; Cecchi, Joseph L. (University of New Mexico Albuquerque, NM); van Swol, Frank B.; Singh, Seema; Rempe, Susan B.; Brinker, C. Jeffrey; Clawson, Jacalyn S.; Feibelman, Peter Julian; Houston, Jack E.; Crozier, Paul Stewart; Criscenti, Louise Jacqueline; Chen, Zhu (University of New Mexico Albuquerque, NM); Zhu, Xiaoyang (University of Minnesota, Minneapolis, MN); Dunphy, Darren Robert (University of New Mexico Albuquerque, NM); Orendorff, Christopher J.; Pless, Jason D.; Daemen, Luke L. (Los Alamos National Laboratory, Los Alamos, NM); Gerung, Henry (University of New Mexico Albuquerque, NM); Ockwig, Nathan W.; Nenoff, Tina Maria; Jiang, Ying-Bing; Stevens, Mark Jackson

    2008-09-01

    A molecular-scale interpretation of interfacial processes is often downplayed in the analysis of traditional water treatment methods. However, such an approach is critical for the development of enhanced performance in traditional desalination and water treatments. Water confined between surfaces, within channels, or in pores is ubiquitous in technology and nature. Its physical and chemical properties in such environments are unpredictably different from bulk water. As a result, advances in water desalination and purification methods may be accomplished through an improved analysis of water behavior in these challenging environments using state-of-the-art microscopy, spectroscopy, experimental, and computational methods.

  5. Interfacial Phenomena: Linking Atomistic and Molecular Level Processes

    Energy Technology Data Exchange (ETDEWEB)

    Jay A Brandes

    2009-09-23

    This was a grant to support travel for scientists to present data and interact with others in their field. Specifically, speakers presented their data in a session entitled “Interfacial Phenomena: Linking Atomistic and Macroscopic Properties: Theoretical and Experimental Studies of the Structure and Reactivity of Mineral Surfaces”. The session ran across three ½ day periods, March 30-31 2004. The session’s organizers were David J. Wesolowski andGordon E. Brown Jr. There were a total of 30 talks presented.

  6. Controlling Interdiffusion, Interfacial Composition, and Adhesion in Polymer Solar Cells

    KAUST Repository

    Dupont, Stephanie R.

    2014-07-10

    © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. NEXAFS spectroscopy is used to precisely quantify the interfacial composition and P3HT chain orientation at the weak P3HT:PCBM/PEDOT:PSS interface. An increase of P3HT:PCBM and PEDOT:PSS interdiffusion with post electrode deposition annealing time and temperature is found to be the underlying mechanism for effectively improving the interlayer adhesion, which is essential for the commercial realization of organic photovoltaic devices.

  7. Forecasting for dynamic line rating

    DEFF Research Database (Denmark)

    Michiorri, Andrea; Nguyen, Huu-Minh; Alessandrini, Stefano

    2015-01-01

    This paper presents an overview of the state of the art on the research on Dynamic Line Rating forecasting. It is directed at researchers and decision-makers in the renewable energy and smart grids domain, and in particular at members of both the power system and meteorological community. Its aim...... on environmental conditions such as the value of ambient temperature, solar radiation, and wind speed and direction. Currently, conservative static seasonal estimations of meteorological values are used to determine ampacity. In a DLR framework, the ampacity is estimated in real time or quasi-real time using...... sensors on the line that measure conductor temperature, tension, sag or environmental parameters such as wind speed and air temperature. Because of the conservative assumptions used to calculate static seasonal ampacity limits and the variability of weather parameters, DLRs are considerably higher than...

  8. Improvement of interfacial adhesion and nondestructive damage evaluation for plasma-treated PBO and Kevlar fibers/epoxy composites using micromechanical techniques and surface wettability.

    Science.gov (United States)

    Park, Joung-Man; Kim, Dae-Sik; Kim, Sung-Ryong

    2003-08-15

    Comparison of interfacial properties and microfailure mechanisms of oxygen-plasma treated poly(p-phenylene-2,6-benzobisoxazole (PBO, Zylon) and poly(p-phenylene terephthalamide) (PPTA, Kevlar) fibers/epoxy composites were investigated using a micromechanical technique and nondestructive acoustic emission (AE). The interfacial shear strength (IFSS) and work of adhesion, Wa, of PBO or Kevlar fiber/epoxy composites increased with oxygen-plasma treatment, due to induced hydrogen and covalent bondings at their interface. Plasma-treated Kevlar fiber showed the maximum critical surface tension and polar term, whereas the untreated PBO fiber showed the minimum values. The work of adhesion and the polar term were proportional to the IFSS directly for both PBO and Kevlar fibers. The microfibril fracture pattern of two plasma-treated fibers appeared obviously. Unlike in slow cooling, in rapid cooling, case kink band and kicking in PBO fiber appeared, whereas buckling in the Kevlar fiber was observed mainly due to compressive and residual stresses. Based on the propagation of microfibril failure toward the core region, the number of AE events for plasma-treated PBO and Kevlar fibers increased significantly compared to the untreated case. The results of nondestructive AE were consistent with microfailure modes.

  9. Relations between interfacial properties and heavy crude oil emulsions stability; Relations entre les proprietes interfaciales et la stabilite des emulsions de brut lourd

    Energy Technology Data Exchange (ETDEWEB)

    Hoebler-Poteau, S.

    2006-02-15

    Oil in water emulsions are currently being investigated to facilitate the transport of viscous heavy oils. The behavior of these emulsions is largely controlled by oil / water interfaces. The surface-active components of crude oil such as asphaltenes and naphthenic acids compete among themselves at these interfaces and also with possibly added synthetic surfactant emulsifier.Here, we present a study of dynamic interfacial tension and rheology of interfaces between water and a model oil (toluene) in which asphaltenes and other surface active molecules from crude oil are dissolved. We show that different parameters such as aging of the interface, asphaltenes concentration, the pH and salinity of the aqueous phase have a strong influence on interfacial properties of asphaltenes at the oil/water interface. Several micro-pipette experiments, in which micrometric drops have been manipulated, are described as well as small angle neutron scattering measurements. The influence of lower molecular weight surface-active species, such as the natural naphthenic acids contained in maltenes (crude oil without asphaltenes) has been investigated, and an interaction between asphaltenes and maltenes which facilitates molecular arrangement at the interface was detected. The microscopic properties of the different interfaces and the stability of the corresponding emulsions are determined to be correlated.The results obtained on model emulsions and model oil/water interfaces were found to be helpful in order to explain and predict the behavior of heavy crude oil emulsions. (author)

  10. Ethnography in community psychology: promises and tensions.

    Science.gov (United States)

    Case, Andrew D; Todd, Nathan R; Kral, Michael J

    2014-09-01

    Community psychology recognizes the need for research methods that illuminate context, culture, diversity, and process. One such method, ethnography, has crossed into multiple disciplines from anthropology, and indeed, community psychologists are becoming community ethnographers. Ethnographic work stands at the intersection of bridging universal questions with the particularities of people and groups bounded in time, geographic location, and social location. Ethnography is thus historical and deeply contextual, enabling a rich, in-depth understanding of communities that is aligned with the values and goals of community psychology. The purpose of this paper is to elucidate the potential of ethnography for community psychology and to encourage its use within the field as a method to capture culture and context, to document process, and to reveal how social change and action occur within and through communities. We discuss the method of ethnography, draw connections to community psychology values and goals, and identify tensions from our experiences doing ethnography. Overall, we assert that ethnography is a method that resonates with community psychology and present this paper as a resource for those interested in using this method in their research or community activism.

  11. Ocular Blood Flow and Normal Tension Glaucoma

    Directory of Open Access Journals (Sweden)

    Ning Fan

    2015-01-01

    Full Text Available Normal tension glaucoma (NTG is known as a multifactorial optic neuropathy characterized by progressive retinal ganglion cell death and glaucomatous visual field loss, even though the intraocular pressure (IOP does not exceed the normal range. The pathophysiology of NTG remains largely undetermined. It is hypothesized that the abnormal ocular blood flow is involved in the pathogenesis of this disease. A number of evidences suggested that the vascular factors played a significant role in the development of NTG. In recent years, the new imaging techniques, fluorescein angiography, color Doppler imaging (CDI, magnetic resonance imaging (MRI, and laser speckle flowgraphy (LSFG, have been used to evaluate the ocular blood flow and blood vessels, and the impaired vascular autoregulation was found in patients with NTG. Previous studies showed that NTG was associated with a variety of systemic diseases, including migraine, Alzheimer’s disease, primary vascular dysregulation, and Flammer syndrome. The vascular factors were involved in these diseases. The mechanisms underlying the abnormal ocular blood flow in NTG are still not clear, but the risk factors for glaucomatous optic neuropathy likely included oxidative stress, vasospasm, and endothelial dysfunction.

  12. Tension tests of concrete containment wall elements

    International Nuclear Information System (INIS)

    Schultz, D.M.; Julien, J.T.; Russel, H.G.

    1984-01-01

    Tension tests of concrete containment wall elements were conducted as part of a three-phase research program sponsored by the Electric Power Research Institute (EPRI). The objective of the EPRI experimental/analytical program is twofold. The first objective is to provide the utility industry with a test-verified analytical method for making realistic estimates of actual capacities of reinforced and prestressed concrete containments under internal over-pressurization from postulated degraded core accidents. The second objective is to determine qualitative and quantitative leak rate characteristics of typical containment cross-sections with and without penetrations. This paper covers the experimental portion to the EPRI program. The testing program for Phase 1 included eight large-scale specimens representing elements from the wall of a containment. Each specimen was 60-in (1525-mm) square, 24-in (610-mm) thick, and had full-size reinforcing bars. Six specimens were representative of prototypical reinforced concrete containment designs. The remaining two specimens represented prototypical prestressed containment designs. Various reinforcement configurations and loading arrangements resulted in data that permit comparisons of the effects of controlled variables on cracking and subsequent concrete/reinforcement/liner interaction in containment elements. Subtle differences, due to variations in reinforcement patterns and load applications among the eight specimens, are being used to benchmark the codes being developed in the analytical portion of the EPRI program. Phases 2 and 3 of the test program will examine leak rate characteristics and failure mechanisms at penetrations and structural discontinuities. (orig.)

  13. [Prozac treatment of chronic tension headache].

    Science.gov (United States)

    Voznesenskaia, T G

    1999-01-01

    The paper summarizes the experience of therapy of chronic tension type headache (TTH) with prozac (fluoxetine)--a selective serotonine reuptake inhibitor. The data are presented concerning clinical psychologic examination of 20 outpatients with chronic TTH both before and after therapy with prozac in daily dose of 20 mg during 6 weeks. Background study of the patients revealed severe depression (according to Beck's and SCL-90 scales), anxiety (Spilberger scale) and alexitimia (Toronto scale). Before the treatment, a frequency of TTH attacks was at least four times a week, the intensivity was equal to 8.9 scores according to visual analogous scale. Together with a headache there were psychopathologic and psychoautonomic manifestations. After the course of therapy the headaches disappeared completely in 25%, while considerable improvement was observed in 75% of the patients. The levels of depression, anxiety, somatization have decreased significantly too. Side effects as well as withdrawal syndrome weren't found. The role of depression in formation of chronic TTH, as well as the role of alixetimia in formation of somatizated variation of the depression were considered.

  14. India: environmental degradation, urban slums, political tension.

    Science.gov (United States)

    Chhabra, R

    1985-09-01

    This article presents an overview of stresses facing Indian society, including population pressures on land and agriculture, topsoil erosion, deforestation, flooding, unemployment, urban slums, and political unrest. Over 60% of India's arable land is estimated to suffer from environmental degradation. This has been caused both by a rapidly growing poor population seeking subsistence and by the misappropriation of natural resources by the wealthy for luxury consumption. Although deforestation is officially cited at 0.37 million acres/year, more sensitive estimates put it at 2.5 million acres/year. Deforestation and massive soil erosion have further created silting, flooding, and pollution in the plains areas of the country. Moreover, the urban population of India is expected to double in the next 15 years to reach a level of 350-400 million. At present, 20-33% of the urban population lives in slums without basic facilities. The employment crisis precipitated by increasing urbanization and migration is expected to be a major problem in the decades ahead. By the year 2000, 7.5 million people will enter the labor force annually. Demographic tension has been a major factor in recent political unrest. Language differences, inequitable access to resources, and the lack of job opportunities have been central issues in these conflicts. Unless more effective means can be found to cope simultaneously with the need to speed up development and meet the needs of a rapidly expanding population, the social and environmental fabric of India is in danger of further erosion.

  15. Muscle tension dysphonia in Vietnamese female teachers.

    Science.gov (United States)

    Nguyen, Duong Duy; Kenny, Dianna T; Tran, Ninh Duy; Livesey, Jonathan R

    2009-03-01

    There has been no published research on muscle tension dysphonia (MTD) in speakers who use a tonal language. Using a sample of 47 Northern Vietnamese female primary school teachers with MTD, we aimed to discover whether professional voice users of tonal languages presented with the same symptoms of MTD as speakers of nontonal languages and whether they presented with additional symptoms as a result of speaking a tonal language. The vocal characteristics were assessed by use of a questionnaire and expert perceptual evaluation. Laryngeal features were assessed by photolaryngoscopy. The results showed that MTD was associated with a larger number of vocal symptoms than previously reported. However, the participants did not have the same vocal symptoms reported in English speakers, for example, hard glottal attack, pitch breaks, unusual speech rate, and glottal fry. Factor analysis of the vocal symptoms revealed three factors: "vocal fatigue/hyperfunction," "physical discomfort," and "voice quality," all of which demonstrated high reliability. The major laryngeal characteristic was a glottal gap. The glottal shapes observed included: 44.7% had an incomplete closure, 29.8% a posterior gap, 12.8% an hourglass-shaped gap, 8.5% a spindle-shaped gap, and 4.3% had complete glottal closure. The findings implied a potential contribution of linguistic-specific factors and teaching-related factors to the presentation of this voice disorder in this group of teachers.

  16. Dense-body aggregates as plastic structures supporting tension in smooth muscle cells.

    Science.gov (United States)

    Zhang, Jie; Herrera, Ana M; Paré, Peter D; Seow, Chun Y

    2010-11-01

    The wall of hollow organs of vertebrates is a unique structure able to generate active tension and maintain a nearly constant passive stiffness over a large volume range. These properties are predominantly attributable to the smooth muscle cells that line the organ wall. Although smooth muscle is known to possess plasticity (i.e., the ability to adapt to large changes in cell length through structural remodeling of contractile apparatus and cytoskeleton), the detailed structural basis for the plasticity is largely unknown. Dense bodies, one of the most prominent structures in smooth muscle cells, have been regarded as the anchoring sites for actin filaments, similar to the Z-disks in striated muscle. Here, we show that the dense bodies and intermediate filaments formed cable-like structures inside airway smooth muscle cells and were able to adjust the cable length according to cell length and tension. Stretching the muscle cell bundle in the relaxed state caused the cables to straighten, indicating that these intracellular structures were connected to the extracellular matrix and could support passive tension. These plastic structures may be responsible for the ability of smooth muscle to maintain a nearly constant tensile stiffness over a large length range. The finding suggests that the structural plasticity of hollow organs may originate from the dense-body cables within the smooth muscle cells.

  17. Low-level laser effects on simulated orthodontic tension side periodontal ligament cells.

    Science.gov (United States)

    Huang, Tsui-Hsien; Liu, Shiau-Lee; Chen, Chih-Lin; Shie, Ming-You; Kao, Chia-Tze

    2013-02-01

    The purpose of this study was to analyze proliferation, inflammation, and osteogenic effects on periodontal ligament (PDL) cells after low-level laser therapy (LLLT) under simulated orthodontic tension conditions. Low-level lasers affect fibroblast proliferation and collagen synthesis and reduce inflammation. Few studies have focused on the LLLT changes in the PDL caused by moving teeth. A human PDL cell line was cultured in a -100 kPa tension incubator. The PDL cells were treated with a 670 nm low-level diode laser, output power of 500 mW (continuous wave modus) for 2.5 or 5 sec, spot area 0.25 cm(2), corresponding to 1.25 and 2.5 J at an energy density of 5 or 10 J/cm(2), respectively. PDL cell viability was assayed by detecting the ability of the cells to cleave tetrazolium salt to formazan dye. Inflammation and osteogenic markers were analyzed by Western blot analysis. PDL cell viablity increased in the experimental group, based on the ability of the cells to cleave tetrazolium salt at day 7 (posteocalcin (OC) expression level was significantly higher at day 7 (p<0.05) than in the control cells. LLLT significantly increased PDL cell proliferation, decreased PDL cell inflammation, and increased PDL OC activity under the tension conditions used in this study.

  18. The Role of Oxygen Tension in Penile Erection and Its Relationship to Erectile Dysfunction

    Directory of Open Access Journals (Sweden)

    Jong-Kwan Park

    2004-01-01

    Full Text Available The corpus cavernosum of the penis is one of the few vascular beds in which there is a change in oxygen tension with function (blood PO2 25-40mm Hg in the flaccid state, and 90-100mm Hg in the erect state. This change in oxygen tension exposes the components of the corpus cavernosum to a variety of cytokines, humoral, vasoactive, and growth factors which may affect the structure and function of the endothelial cells, smooth muscle cells, neurons and extracellular matrix. Among these cell types, endothelial cells are the first line of defense to blood-borne stress and can affect the underlying smooth muscle via paracrine mechanisms. Impotence is defined as the inability to obtain or sustain an erection sufficient for vaginal penetration and can result from a variety of pathological conditions, vascular disease, endocrine disease, neurological disease, and psychogenic disorders. The penis is a vascular organ and as such is susceptible to the effects of vascular diseases. This review will discuss the basic etiology of erection and vasculogenic erectile dysfunction and explore the role oxygen tension in regulating various cellular and humoral factors as well as trabecular structure and function.

  19. FORMALIZATION OF LOCOMOTIVE DRIVER ACTIVITY TENSION INDICATOR BASED ON THE ERGONOMIC MODEL

    Directory of Open Access Journals (Sweden)

    O. M. Horobchenko

    2017-02-01

    Full Text Available Purpose. A key factor contributing to the safety and quality of ergatic system "train-driver" is the intensity of the locomotive crew’s work. The aim of this work is formalization of locomotive driver activity tension indicator. Methodology. One of the characteristics of driver activity tension is the difference between the time allotted to complete the task, and the necessary (external reserve or deficiency time. The sets of major and minor operations in the management of the train locomotive in different train situations were identified. Using the methods of fuzzy logic, the concept of "materiality of the operation of the locomotive control" is presented in the form of a set of linguistic variables. To determine the function membership of the elements of the set "the importance of the operation of the locomotive control" the method of expert evaluations was used. Coefficient of temporary tension is presented in the form of fuzzy number L-R-type. Findings. It was found the value of the relative number of operations of locomotive control according to the distribution using the parameter of operation "importance". To determine the most tensioned mode of the driver ranking the traffic condition according to the parameter of relative amounts of the important management operations was conducted. The most difficult modes are the "front hindrance", "movement in unfavorable weather conditions" and "departure from the station to the running line". Originality. The introduction of the value "conventional importance of the operation" allowed us to more accurately describe the terms of train driving. For the first time the work presents determination of tension of the driver’s work in the form of a unimodal fuzzy number, which will make it possible to use the methods of the theory of artificial intelligence to simulate activity of the locomotive driver and develop intelligent control systems. Practical value. There were obtained the opportunity to

  20. Linear interfacial polymerization: theory and simulations with dissipative particle dynamics.

    Science.gov (United States)

    Berezkin, Anatoly V; Kudryavtsev, Yaroslav V

    2014-11-21

    Step-growth alternating interfacial polymerization between two miscible or immiscible monomer melts is investigated theoretically and by dissipative particle dynamics simulations. In both cases the kinetics for an initially bilayer system passes from the reaction to diffusion control. The polymer composed of immiscible monomers precipitates at the interface forming a film of nearly uniform density. It is demonstrated that the reaction proceeds in a narrow zone, which expands much slower than the whole film, so that newly formed polymer is extruded from the reaction zone. This concept of "reactive extrusion" is used to analytically predict the degree of polymerization and distribution of all components (monomers, polymer, and end groups) within the film in close agreement with the simulations. Increasing the comonomer incompatibility leads to thinner and more uniform films with the higher average degree of polymerization. The final product is considerably more polydisperse than expected for the homogeneous step-growth polymerization. The results extend the previous theoretical reports on interfacial polymerization and provide new insights into the internal film structure and polymer characteristics, which are important for membrane preparation, microencapsulation, and 3D printing technologies. A systematic way of mapping the simulation data onto laboratory scales is discussed.