WorldWideScience

Sample records for surface tension orthobaric

  1. Surface Tension of Spacetime

    Science.gov (United States)

    Perko, Howard

    2017-01-01

    Concepts from physical chemistry and more specifically surface tension are introduced to spacetime. Lagrangian equations of motion for membranes of curved spacetime manifold are derived. The equations of motion in spatial directions are dispersion equations and can be rearranged to Schrodinger's equation where Plank's constant is related to membrane elastic modulus. The equation of motion in the time-direction has two immediately recognizable solutions: electromagnetic waves and corpuscles. The corpuscular membrane solution can assume different genus depending on quantized amounts of surface energy. A metric tensor that relates empty flat spacetime to energetic curved spacetime is found that satisfies general relativity. Application of the surface tension to quantum electrodynamics and implications for quantum chromodynamics are discussed. Although much work remains, it is suggested that spacetime surface tension may provide a classical explanation that combines general relativity with field theories in quantum mechanics and atomic particle physics.

  2. Introducing surface tension to spacetime

    Science.gov (United States)

    Perko, H. A.

    2017-05-01

    Concepts from physical chemistry of surfaces and surface tension are applied to spacetime. More specifically, spacetime is modeled as a spatial fluid continuum bound together by a multi-dimensional membrane of time. A metric tensor that relates empty flat spacetime to energetic curved spacetime is found. Equations of motion for an infinitesimal unit of spacetime are derived. The equation of motion in a time-like direction is a Klein-Gordon type equation. The equations of motion in space-like directions take the form of Schrodinger’s equation where Plank’s constant is related to membrane elastic modulus. Although much work remains, it is suggested that the spacetime surface tension may serve as a mechanical model for many phenomena in quantum mechanics and atomic particle physics.

  3. Axelrod's Model with Surface Tension

    CERN Document Server

    Pace, Bruno

    2012-01-01

    In this work we propose a subtle change in Axelrod's model for the dissemination of culture. The mechanism consists of excluding non-interacting neighbours from the set of neighbours out of which an agent is drawn for potential cultural interactions. Although the alteration proposed does not alter topologically the configuration space, it yields significant qualitative changes, specifically the emergence of surface tension, driving the system in some cases to metastable states. The transient behaviour is considerably richer, and cultural regions have become stable leading to the formation of different spatio-temporal structures. A new metastable "glassy" phase emerges between the globalised phase and the polarised, multicultural phase.

  4. Surface tension profiles in vertical soap films

    CERN Document Server

    Adami, N

    2013-01-01

    Surface tension profiles in vertical soap films are experimentally investigated. Measurements are performed introducing deformable elastic objets in the films. The shape adopted by those objects set in the film can be related to the surface tension value at a given vertical position by numerical solving of adapted elasticity equations. We show that the observed dependency of the surface tension versus the vertical position in the soap film can be reproduced by simple modeling taking into account film thickness measurements.

  5. On Surface Tension for Compact Stars

    Indian Academy of Sciences (India)

    R. Sharma; S. D. Maharaj

    2007-06-01

    In an earlier analysis it was demonstrated that general relativity gives higher values of surface tension in strange stars with quark matter than neutron stars. We generate the modified Tolman–Oppenheimer–Volkoff equation to incorporate anisotropic matter and use this to show that pressure anisotropy provides for a wide range of behaviour in the surface tension than is the case with isotropic pressures. In particular, it is possible that anisotropy drastically decreases the value of the surface tension.

  6. Surface Tension Calculation of Undercooled Alloys

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on the Butler equation and extrapolated thermodynamic data of undercooled alloys from those of liquid stable alloys, a method for surface tension calculation of undercooled alloys is proposed. The surface tensions of liquid stable and undercooled Ni-Cu (xNi=0.42) and Ni-Fe (xNi=0.3 and 0.7) alloys are calculated using STCBE (Surface Tension Calculation based on Butler Equation) program. The agreement between calculated values and experimental data is good enough, and the temperature dependence of the surface tension can be reasonable down to 150-200 K under the liquid temperature of the alloys.

  7. The surface tension of liquid gallium

    Science.gov (United States)

    Hardy, S. C.

    1985-01-01

    The surface tension of liquid gallium has been measured using the sessile drop technique in an Auger spectrometer. The experimental method is described. The surface tension in mJ/sq m is found to decrease linearly with increasing temperature and may be represented as 708-0.66(T-29.8), where T is the temperature in centigrade. This result is of interest because gallium has been suggested as a model fluid for Marangoni flow experiments. In addition, the surface tension is of technological significance in the processing of compound semiconductors involving gallium.

  8. Surface tension profiles in vertical soap films

    Science.gov (United States)

    Adami, N.; Caps, H.

    2015-01-01

    Surface tension profiles in vertical soap films are experimentally investigated. Measurements are performed by introducing deformable elastic objets in the films. The shape adopted by those objects once set in the film is related to the surface tension value at a given vertical position by numerically solving the adapted elasticity equations. We show that the observed dependency of the surface tension versus the vertical position is predicted by simple modeling that takes into account the mechanical equilibrium of the films coupled to previous thickness measurements.

  9. The Dynamic Surface Tension of Water.

    Science.gov (United States)

    Hauner, Ines M; Deblais, Antoine; Beattie, James K; Kellay, Hamid; Bonn, Daniel

    2017-03-23

    The surface tension of water is an important parameter for many biological or industrial processes, and roughly a factor of 3 higher than that of nonpolar liquids such as oils, which is usually attributed to hydrogen bonding and dipolar interactions. Here we show by studying the formation of water drops that the surface tension of a freshly created water surface is even higher (∼90 mN m(-1)) than under equilibrium conditions (∼72 mN m(-1)) with a relaxation process occurring on a long time scale (∼1 ms). Dynamic adsorption effects of protons or hydroxides may be at the origin of this dynamic surface tension. However, changing the pH does not significantly change the dynamic surface tension. It also seems unlikely that hydrogen bonding or dipole orientation effects play any role at the relatively long time scale probed in the experiments.

  10. Surface tension effects in breaking wave noise.

    Science.gov (United States)

    Deane, Grant B

    2012-08-01

    The role of surface active materials in the sea surface microlayer on the production of underwater noise by breaking waves is considered. Wave noise is assumed to be generated by bubbles formed within actively breaking whitecaps, driven into breathing mode oscillation at the moment of their formation by non-equilibrium, surface tension forces. Two significant effects associated with surface tension are identified-a reduction in low frequency noise (bubbles by fluid turbulence within the whitecap and a reduction in overall noise level due to a decrease in the excitation amplitude of bubbles associated with reduced surface tension. The impact of the latter effect on the accuracy of Weather Observations Through Ambient Noise estimates of wind speed is assessed and generally found to be less than ±1 m s(-1) for wind speeds less than 10 m s(-1) and typical values of surfactant film pressure within sea slicks.

  11. Statistical Mechanics of Multilayer Sorption: Surface Tension.

    Science.gov (United States)

    Wexler, Anthony S; Dutcher, Cari S

    2013-05-16

    Mathematical models of surface tension as a function of solute concentration are needed for predicting the behavior of surface processes relevant to the environment, biology, and industry. Current aqueous surface tension-activity models capture either solutions of electrolytes or those of nonelectrolytes, but a single equation has not yet been found that represents both over the full range of compositions. In prior work, we developed an accurate model of the activity-concentration relationship in solutions over the full range of compositions by extending the BET (Brunauer, Emmett, Teller) and GAB (Guggenheim, Anderson, de Boer) isotherms to multiple monolayers of solvent molecules sorbed to solutes. Here, we employ similar statistical mechanical tools to develop a simple equation for the surface tension-activity relationship that differs remarkably from prior formulations in that it (1) works equally well for nonelectrolyte and electrolyte solutes and (2) is accurate over the full range of concentrations from pure solvent to pure solute.

  12. Surface-tension properties of hyaluronic Acid.

    Science.gov (United States)

    Knepper, P A; Covici, S; Fadel, J R; Mayanil, C S; Ritch, R

    1995-06-01

    The maintenance of flow channels in the trabecular meshwork is dependent, in part, on the patency of the trabecular spaces. Because the amount of hyaluronic acid decreases in the trabecular meshwork of patients with primary open-angle glaucoma, a change in surface tension may be one of the effects of hyaluronic acid on aqueous outflow. The surface-active properties of hyaluronic acid (concentration of 0.156-2.5 mg/ml; molecular weights of 100,000, 500,000, and 4,000,000) in deionized water, Ringer's lactate, Ringer's lactate plus 0.06 mg/ml bovine serum albumin, and mock aqueous solution were tested using the drop volume method. At a hyaluronic acid concentration of 0.312 mg/ml, surface tension decreased; at higher concentrations, a further decrease in surface tension was observed. In the presence of Ringer's lactate, the 100,000-MW hyaluronic acid was more active than the 4,000,000-MW hyaluronic acid. In the presence of Ringer's lactate plus bovine serum albumin or mock aqueous solution, the influence of surface tension of the 100,000-MW hyaluronic acid was moderated: with lower hyaluronic acid concentrations, the decline in surface tension was more than with Ringer's lactate, but with higher hyaluronic acid concentrations, the decline in surface tension was less than with Ringer's lactate. At high concentration, hyaluronic acid behaves like a non-Newtonian fluid, becomes more viscous, and may act to "seal" the trabecular space. The results of this study indicate that hyaluronic acid possesses surface-active properties, which is just one of several properties of hyaluronic acid that may influence aqueous outflow resistance.

  13. Dynamic Surface Tensions of Fluorous Surfactant Solutions

    Institute of Scientific and Technical Information of China (English)

    高艳安; 侯万国; 王仲妮; 李干佐; 韩布兴; 张高勇; 吕锋锋

    2005-01-01

    Dynamic surface properties of aqueous solutions of cationic fluorous surfactant CF3CF2CF20(CF(CF3)CF2O)2CF(CF3)CONH(CHE)3N+(C2H5)2CH3I- (abbrev. FC-4 ) were reported. The critical micelle concentration (cmc)(3.6×10-5 mol/L) and equilibdum surface tensions γeq were measured by Krtlss K12 tension apparatus. Dynamic surface tension γ(t) was measured in the range of 15 ms to 200 s using the MBP tensiometer. The surface excess Γ,as a function of concentration, was obtained from equilibrium tensiometry using the Gibbs equation. Data from these experiments were combined to analyze the γ(t) decays according to the asymptotic Ward and Tordai equation.The results show that at the initial adsorption stage, the dynamic surface tension data were all consistent with this diffusion-controlled mechanism, and at the end of the adsorption process, there were some evidences for an adsorption barrier, suggesting a mixed diffusion-controlled adsorption mechanism. Using measured quantities, the barrier strength was estimated as between 25 and 35 kJ/mol at 25℃. The surface pressure plays an important role in contributing to the barrier.

  14. Surface tension of evaporating nanofluid droplets

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ruey-Hung [Univ. of Central Florida, Orlando, FL (United States); Phuoc, Tran X. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Martello, Donald [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States)

    2011-05-01

    Measurements of nanofluid surface tension were made using the pendant droplet method. Three different types of nanoparticles were used - laponite, silver and Fe2O3 - with de-ionized water (DW) as the base fluid. The reported results focus on the following categories; (1) because some nanoparticles require surfactants to form stable colloids, the individual effects of the surfactant and the particles were investigated; (2) due to evaporation of the pendant droplet, the particle concentration increases, affecting the apparent surface tension; (3) because of the evaporation process, a hysteresis was found where the evaporating droplet can only achieve lower values of surface tension than that of nanofluids at the same prepared concentrations: and (4) the Stefan equation relating the apparent surface tension and heat of evaporation was found to be inapplicable for nanofluids investigated. Comparisons with findings for sessile droplets are also discussed, pointing to additional effects of nanoparticles other than the non-equilibrium evaporation process.

  15. Surface Tension Driven Convection Experiment Completed

    Science.gov (United States)

    Jacobson, Thomas P.; Sedlak, Deborah A.

    1997-01-01

    The Surface Tension Driven Convection Experiment (STDCE) was designed to study basic fluid mechanics and heat transfer on thermocapillary flows generated by temperature variations along the free surfaces of liquids in microgravity. STDCE first flew on the USML-1 mission in July 1992 and was rebuilt for the USML-2 mission that was launched in October 1995. This was a collaborative project with principal investigators from Case Western Reserve University (CWRU), Professors Simon Ostrach and Yasuhiro Kamotani, along with a team from the NASA Lewis Research Center composed of civil servants and contractors from Aerospace Design & Fabrication, Inc. (ADF), Analex, and NYMA, Inc.

  16. Dropwise Condensation of Low Surface Tension Fluids on Omniphobic Surfaces

    Science.gov (United States)

    Rykaczewski, Konrad; Paxson, Adam T.; Staymates, Matthew; Walker, Marlon L.; Sun, Xiaoda; Anand, Sushant; Srinivasan, Siddarth; McKinley, Gareth H.; Chinn, Jeff; Scott, John Henry J.; Varanasi, Kripa K.

    2014-03-01

    Compared to the significant body of work devoted to surface engineering for promoting dropwise condensation heat transfer of steam, much less attention has been dedicated to fluids with lower interfacial tension. A vast array of low-surface tension fluids such as hydrocarbons, cryogens, and fluorinated refrigerants are used in a number of industrial applications, and the development of passive means for increasing their condensation heat transfer coefficients has potential for significant efficiency enhancements. Here we investigate condensation behavior of a variety of liquids with surface tensions in the range of 12 to 28 mN/m on three types of omniphobic surfaces: smooth oleophobic, re-entrant superomniphobic, and lubricant-impregnated surfaces. We demonstrate that although smooth oleophobic and lubricant-impregnated surfaces can promote dropwise condensation of the majority of these fluids, re-entrant omniphobic surfaces became flooded and reverted to filmwise condensation. We also demonstrate that on the lubricant-impregnated surfaces, the choice of lubricant and underlying surface texture play a crucial role in stabilizing the lubricant and reducing pinning of the condensate. With properly engineered surfaces to promote dropwise condensation of low-surface tension fluids, we demonstrate a four to eight-fold improvement in the heat transfer coefficient.

  17. 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

  18. Steady periodic gravity waves with surface tension

    CERN Document Server

    Walsh, Samuel

    2009-01-01

    In this paper we consider two-dimensional, stratified, steady water waves propagating over an impermeable flat bed and with a free surface. The motion is assumed to be driven by capillarity (that is, surface tension) on the surface and a gravitational force acting on the body of the fluid. We prove the existence of global continua of classical solutions that are periodic and traveling. This is accomplished by first constructing a 1-parameter family of laminar flow solutions, $\\mathcal{T}$, then applying bifurcation theory methods to obtain local curves of small amplitude solutions branching from $\\mathcal{T}$ at an eigenvalue of the linearized problem. Each solution curve is then continued globally by means of a degree theoretic theorem in the spirit of Rabinowitz. Finally, we complement the degree theoretic picture by proving an alternate global bifurcation theorem via the analytic continuation method of Dancer.

  19. Theoretical and experimental study on surface tension and dynamic surface tension of aqueous lithium bromide and water with additive

    Institute of Scientific and Technical Information of China (English)

    程文龙; 陈则韶; 秋泽淳; 胡芃; 柏木孝夫

    2003-01-01

    The surface tensions of water and aqueous lithium bromide (LiBr) with 2-ethyl-1-hexa- nol (2EH) and 1-octanol were measured using Wilhelmy plate method, and the oscillation of surface tension under the open condition for LiBr solution was observed. The dynamic surface tensions of water and LiBr solution in the presence of the 2EH and 1-octanol vapor were measured in this paper. The results showed that the additives vapor could obviously affect surface tension. For water, the dynamic surface tension was also affected by the mass of the tested liquid; however, for LiBr solution, the dynamic surface tension was not related to the mass of the tested solution. According to the experimental results, the hypothesis that surface tension varies linearly with the surface excess concentration is advanced, which could overcome the limit of Gibbs equation. The equations of surface absorption and desorption are modified, the units of the adsorption coefficient and desorption coefficient are unified; the effects of the liquid and vapor of additive on the surface tension are unified; the theoretical relations of the static surface tension and dynamic surface tension with the relative contents of the liquid and vapor of additive are obtained under the combined actions of them; the theoretical equations are validated by the experiments results.

  20. Surface tension propulsion of fungal spores.

    Science.gov (United States)

    Noblin, Xavier; Yang, Sylvia; Dumais, Jacques

    2009-09-01

    Most basidiomycete fungi actively eject their spores. The process begins with the condensation of a water droplet at the base of the spore. The fusion of the droplet onto the spore creates a momentum that propels the spore forward. The use of surface tension for spore ejection offers a new paradigm to perform work at small length scales. However, this mechanism of force generation remains poorly understood. To elucidate how fungal spores make effective use of surface tension, we performed a detailed mechanical analysis of the three stages of spore ejection: the transfer of energy from the drop to the spore, the work of fracture required to release the spore from its supporting structure and the kinetic energy of the spore after ejection. High-speed video imaging of spore ejection in Auricularia auricula and Sporobolomyces yeasts revealed that drop coalescence takes place over a short distance ( approximately 5 microm) and energy transfer is completed in less than 4 mus. Based on these observations, we developed an explicit relation for the conversion of surface energy into kinetic energy during the coalescence process. The relation was validated with a simple artificial system and shown to predict the initial spore velocity accurately (predicted velocity: 1.2 m s(-1); observed velocity: 0.8 m s(-1) for A. auricula). Using calibrated microcantilevers, we also demonstrate that the work required to detach the spore from the supporting sterigma represents only a small fraction of the total energy available for spore ejection. Finally, our observations of this unique discharge mechanism reveal a surprising similarity with the mechanics of jumping in animals.

  1. 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).

  2. Modifying horizon thermodynamics by surface tensions

    CERN Document Server

    Chen, Deyou

    2016-01-01

    The modified first laws of thermodynamics at the black hole horizon and the cosmological horizon of the Schwarzschild de Sitter black hole and the apparent horizon of the Friedmann-Robertson-Walker cosmology are derived by the surface tensions, respectively. The corresponding Smarr relations are obeyed. For the black hole, the cosmological constant is first treated as a fixed constant, and then as a variable associated to the pressure. The law at the apparent horizon takes the same form as that at the cosmological horizon, but is different from that at the black hole horizon. The positive temperatures guarantee the appearance of the worked terms in the modified laws at the cosmological and apparent horizons. While they can disappear at the black hole horizon.

  3. Tunable Superomniphobic Surfaces for Sorting Droplets by Surface Tension

    Science.gov (United States)

    Movafaghi, Sanli; Wang, Wei; Metzger, Ari; Williams, Desiree; Williams, John; Kota, Arun

    2016-11-01

    Manipulation of liquid droplets on super-repellent surfaces (i.e., surfaces that are extremely repellent to liquids) has been widely studied because droplets exhibit high mobility on these surfaces due to the ultra-low adhesion, which leads to minimal sample loss and contamination. Although droplet manipulation has been demonstrated using electric fields, magnetic fields, guiding tracks and wettability gradients, to the best of our knowledge, there are no reports of droplet manipulation methods that can sort droplets by surface tension on super-repellent surfaces. In this work, we utilized tunable superomniphobic surfaces (i.e., surfaces that are extremely repellent to virtually all liquids) to develop a simple device with precisely tailored solid surface energy domains that, for the first time, can sort droplets by surface tension. Droplet sorting occurs on our device entirely due to a balance between the work done by gravity and the work expended due to adhesion, without the need for any external energy input. Our device can be fabricated easily in a short time and is particularly useful for in-the-field and on-the-go operations, where complex analysis equipment is unavailable. We envision that our methodology for droplet sorting will enable inexpensive and energy-efficient analytical devices for personalized point-of-care diagnostic platforms and lab-on-a-chip systems.

  4. Surface tension and long range corrections of cylindrical interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bourasseau, E. [CEA/DAM DIF, F-91297 Arpajon Cedex (France); Malfreyt, P. [Université Clermont Auvergne, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); Ghoufi, A., E-mail: aziz.ghoufi@univ-rennes1.fr [Institut de Physique de Rennes, UMR 6251 CNRS, Université de Rennes 1, 263 avenue Général Leclerc, 35042 Rennes (France)

    2015-12-21

    The calculation of the surface tension of curved interfaces has been deeply investigated from molecular simulation during this last past decade. Recently, the thermodynamic Test-Area (TA) approach has been extended to the calculation of surface tension of curved interfaces. In the case of the cylindrical vapour-liquid interfaces of water and Lennard-Jones fluids, it was shown that the surface tension was independent of the curvature of the interface. In addition, the surface tension of the cylindrical interface is higher than that of the planar interface. Molecular simulations of cylindrical interfaces have been so far performed (i) by using a shifted potential, (ii) by means of large cutoff without periodic boundary conditions, or (iii) by ignoring the long range corrections to the surface tension due to the difficulty to estimate them. Indeed, unlike the planar interfaces there are no available operational expressions to consider the tail corrections to the surface tension of cylindrical interfaces. We propose here to develop the long range corrections of the surface tension for cylindrical interfaces by using the non-exponential TA (TA2) method. We also extend the formulation of the Mecke-Winkelmann corrections initially developed for planar surfaces to cylindrical interfaces. We complete this study by the calculation of the surface tension of cylindrical surfaces of liquid tin and copper using the embedded atom model potentials.

  5. Surface tension and related thermodynamic quantities of aqueous electrolyte solutions

    CERN Document Server

    Matubayasi, Norihiro

    2013-01-01

    Surface tension provides a thermodynamic avenue for analyzing systems in equilibrium and formulating phenomenological explanations for the behavior of constituent molecules in the surface region. While there are extensive experimental observations and established ideas regarding desorption of ions from the surfaces of aqueous salt solutions, a more successful discussion of the theory has recently emerged, which allows the quantitative calculation of the distribution of ions in the surface region. Surface Tension and Related Thermodynamic Quantities of Aqueous Electrolyte Solutions provides a d

  6. Surface tension of molten tin investigated with sessile drop method

    Institute of Scientific and Technical Information of China (English)

    LI Jing; YUAN Zhang-fu; FAN Jian-feng; KE Jia-jun

    2005-01-01

    The surface tension of molten tin was determined by a set of self-developed digital equipment with sessile drop method at oxygen partial pressure of 1.0 × 10-6 MPa under different temperatures, and the dependence of surface tension of molten tin on temperature was also discussed. The emphasis was placed on the comparison of surface tension of the same molten tin sample measured by using different equipments with sessile drop method. Results of the comparison indicate that the measurement results with sessile drop method under the approximate experimental conditions are coincident, and the self-developed digital equipment for surface tension measurement has higher stability and accuracy. The relationships of surface tension of molten tin and its temperature coefficient with temperature and oxygen partial pressure were also elucidated from the thermodynamic equilibrium analysis.

  7. Energy conversion by surface-tension driven charge separation

    CERN Document Server

    Pini, Cesare; Dietzel, Mathias

    2016-01-01

    In this work, the shear-induced electrokinetic streaming potential present in free-surface electrolytic flows subjected to a gradient in surface tension is assessed. Firstly, for a Couette flow with fully resolved electric double layer (EDL), the streaming potential per surface stress as a function of the Debye parameter and surface potential is analyzed. By contrast to the Smoluchowski limit in pressure-driven channel flow, the shear-induced streaming potential vanishes for increasing Debye parameter (infinitely thin EDL), unless the free surface contains (induced) surface charge or the flow at the charged, solid wall is permitted to slip. Secondly, a technical realization of surface-tension induced streaming is proposed, with surface stress acting on the free (slipping) surfaces of a micro-structured, superhydrophobic wall. The streaming potential is analyzed with respect to the slip parameter and surface charge. Finally, the surface tension is assumed to vary with temperature (thermocapillarity) or with su...

  8. Geometric Interpretation of Surface Tension Equilibrium in Superhydrophobic Systems

    Directory of Open Access Journals (Sweden)

    Michael Nosonovsky

    2015-07-01

    Full Text Available Surface tension and surface energy are closely related, although not identical concepts. Surface tension is a generalized force; unlike a conventional mechanical force, it is not applied to any particular body or point. Using this notion, we suggest a simple geometric interpretation of the Young, Wenzel, Cassie, Antonoff and Girifalco–Good equations for the equilibrium during wetting. This approach extends the traditional concept of Neumann’s triangle. Substances are presented as points, while tensions are vectors connecting the points, and the equations and inequalities of wetting equilibrium obtain simple geometric meaning with the surface roughness effect interpreted as stretching of corresponding vectors; surface heterogeneity is their linear combination, and contact angle hysteresis is rotation. We discuss energy dissipation mechanisms during wetting due to contact angle hysteresis, the superhydrophobicity and the possible entropic nature of the surface tension.

  9. The effects of ambient impurities on the surface tension

    Directory of Open Access Journals (Sweden)

    Ponce-Torres A.

    2016-01-01

    Full Text Available A liquid bridge is a liquid column held captive between two coaxial and parallel solid disks. It is an excellent test bench where measuring the surface tension. In this paper, we used this fluid configuration to examine experimentally the effects of ambient impurities on the surface tension over time. For this purpose, the liquid bridge equilibrium shape was analyzed when the liquid bridge was surrounded by three environments: the uncontrolled ambient, and both air and argon encapsulated in a small glass cover. Ambient contamination produced a sharp decrease of the surface tension of ultra-pure water. The presence of an anionic surfactant in the free surface of an aqueous solution did not inhibit the action of impurities coming from the ambient. Impurities can influence the dynamical behavior of the free surface in flows dominated by the surface tension. Therefore, a careful control of that influence can be crucial in many applications of fluid mechanics.

  10. Nonzero Ideal Gas Contribution to the Surface Tension of Water.

    Science.gov (United States)

    Sega, Marcello; Fábián, Balázs; Jedlovszky, Pál

    2017-06-15

    Surface tension, the tendency of fluid interfaces to behave elastically and minimize their surface, is routinely calculated as the difference between the lateral and normal components of the pressure or, invoking isotropy in momentum space, of the virial tensor. Here we show that the anisotropy of the kinetic energy tensor close to a liquid-vapor interface can be responsible for a large part of its surface tension (about 15% for water, independent from temperature).

  11. Molecular dynamics simulation of liquid-vapor surface tension

    Institute of Scientific and Technical Information of China (English)

    王德; ZENG; Danling; 等

    2002-01-01

    A molecular dynamics simulation model is established based on the well-known Lennard-Jones 12-6 potential function to determine the surface tension of a Lennard-Jones liquid-vapor interface.The simulation is carried out with argon as the working fluid of a given molecular number at different temperature and different truncated radius.It is found that the surface tension of a Lennard-Jones fluid is likely to be bigger for a bigger truncated radius,and tends to be constant after the truncated radius increased to a certain value.It is also found that the surface tension becomes smaller as the temperature increases.

  12. Surface Tension of Molten Ni and Ni-Co Alloys

    Institute of Scientific and Technical Information of China (English)

    Feng XIAO; Liang FANG; Kiyoshi NOGI

    2005-01-01

    Surface tension of molten Ni and Ni-Co (5 and 10 mass fraction) alloys was measured at the temperature range of 1773~1873 K using an improved sessile drop method with an alumina substrate in an Ar+3%H2 atmosphere. The error of the data obtained was analyzed. The surface tension of molten Ni and Ni-Co (5 and 10 mass fraction) alloys decreases with increasing temperature. The influence of Co on the surface tension of Ni-Co alloys is little in the studied Co concentration range.

  13. Surface tension of liquid Au-Bi-Sn alloys

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The surface tension of a promising lead-free solder Au-Bi-Sn alloys was investigated both by the sessile-drop method and calculation. Experimental measurements were carried out for two cross-sections with the constant gold to bismuth ration of 1:1 and 1:2. For all the investigated compositions, decrease of the surface tension is observed with increasing temperature. Meanwhile, the surface tension values were also calculated based on Butler's equation, with using the newest research on thermodynamics data of...

  14. Surface tension of molecular liquids: Lattice gas approach

    CERN Document Server

    Maslechko, A; Kulinskii, V

    2016-01-01

    The approach of global isomorphism between the fluid and the Ising model is applied to obtain an expression for the surface tension of the Lennard-Jones fluid on the basis of the information about the Ising model. This is done in a broad interval of temperatures along the phase coexistence, and is valid both in 2D and 3D. The relation between the critical amplitudes of the surface tension of the fluid and the Ising model is derived in the vicinity of the critical point. The obtained theoretical estimates agree well with the literature results for the surface tension. The methodology is demonstrated for the 2D LJ fluid on the basis of the exact solution of the 2D Ising model and is tested for the 3D LJ fluid. As a result, an expression for the surface tension without any fitting parameter is derived.

  15. Molecular Dynamic Simulations on Surface Tension of Methanol

    Science.gov (United States)

    Obeidat, Abdalla

    2015-04-01

    Molecular dynamic simulations have been performed to study the surface tension of methanol at low temperatures. Six different models of methanol have been studied to compute the surface tension of different models. The models have been used to predict the surface tensions are: OPLS, Gromos 96, H1, J1, J2, and van Leeuwen model. Our results show that the most accurate model compared to true methanol was van Leeuwen model. The results were fitted to a straight line to predict other data of surface tension at specific temperature. The simulation were performed using the Gromacs package at temperatures: 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, and 300 K. This work is supported by JUST.

  16. Second Inflection Point of the Surface Tension of Water

    Science.gov (United States)

    Kalova, Jana; Mares, Radim

    2012-06-01

    The theme of a second inflection point of the temperature dependence of the surface tension of water remains a subject of controversy. Using data above 273 K, it is difficult to get a proof of existence of the second inflection point, because of experimental uncertainties. Data for the surface tension of supercooled water and results of a molecular dynamics study were included into the exploration of existence of an inflection point. A new term was included into the IAPWS equation to describe the surface tension in the supercooled water region. The new equation describes the surface tension values of ordinary water between 228 K and 647 K and leads to the inflection point value at a temperature of about 1.5 °C.

  17. Surface tension of compositions of polyhexametyleneguanidine hydrochloride - surfactants

    Directory of Open Access Journals (Sweden)

    S. Kumargaliyeva

    2012-12-01

    Full Text Available We made up songs bactericidal polyhexamethyleneguanidine hydrochloride (metacyde with the surface-active substances - anionic sodium dodecylsulfate, cationic cetylpyridinium bromide, and nonionic Tween-80 and measured the surface tension of water solutions. The study showed that the composition metacyde with surface-active agents have a greater surface activity than the individual components.

  18. Surface tension of calcium hydroxide associated with different substances

    OpenAIRE

    Carlos Estrela; Cyntia Rodrigues de Araújo Estrela; Luiz Fernando Guimarães; Reginaldo Santana Silva; Jesus Djalma Pécora

    2005-01-01

    The purpose of this study was to evaluate the surface tension of calcium hydroxide (CH) associated with different substances (deionized distilled water, camphorated paramonochlorophenol, 2% chlorhexidine digluconate, Otosporin, 3% sodium lauryl ether sulphate; Furacin, PMC Furacin) using tensiometer. The action of the substances studied on the dentinal structure enhances the property of surface tension. This method consists in the application of force to separate a platinum ring immersed in t...

  19. Surface Tension between Kaon Condensate and Normal Nuclear Matter Phase

    OpenAIRE

    Christiansen, Michael B.; Glendenning, Norman K.; Schaffner-Bielich, Jurgen

    2000-01-01

    We calculate for the first time the surface tension and curvature coefficient of a first order phase transition between two possible phases of cold nuclear matter, a normal nuclear matter phase in equilibrium with a kaon condensed phase, at densities a few times the saturation density. We find the surface tension is proportional to the difference in energy density between the two phases squared. Furthermore, we show the consequences for the geometrical structures of the mixed phase region in ...

  20. Surface tension with Normal Curvature in Curved Space-Time

    CERN Document Server

    kumar, Himanshu; Ahmad, Suhail

    2012-01-01

    With an aim to include the contribution of surface tension in the action of the boundary, we define the tangential pressure in terms of surface tension and Normal curvature in a more naturally geometric way. First, we show that the negative tangential pressure is independent of the four-velocity of a very thin hyper-surface. Second, we relate the 3-pressure of a surface layer to the normal curvature and the surface tension. Third, we relate the surface tension to the energy of the surface layer. Four, we show that the delta like energy flows across the hyper-surface will be zero for such a representation of intrinsic 3-pressure. Five, for the weak field approximation and for static spherically symmetric configuration, we deduce the classical Kelvin's relation. Six, we write a modified action for the boundary having contributions both from surface tension and normal curvature of the surface layer. Also we propose a method to find the physical action assuming a reference background, where the background is not ...

  1. Surface Tensions and Their Variations with Temperature and Impurities

    Science.gov (United States)

    Hardy, S. C.; Fine, J.

    1985-01-01

    The surface tensions in this work were determined using the sessile drop technique. This method is based on a comparison of the profile of a liquid drop with the profile calculated by solving the Young-Laplace equation. The comparison can be made in several ways; the traditional Bashforth-Adams procedure was used in conjunction with recently calculated drop shape tables which virtually eliminate interpolation errors. Although previous study has found little difference in measurements with pure and oxygen doped silicon, there is other evidence suggesting that oxygen in dilute concentrations severely depresses the surface tension of silicon. The surface tension of liquid silicon in purified argon atmospheres was measured. A temperature coefficient near -0.28 mJ/square meters K was found. The experiments show a high sensitivity of the surface tension to what is believed are low concentrations of oxygen. Thus one cannot rule out some effect of low levels of oxygen in the results. However, the highest surface tension values obtained in conditions which minimized the residual oxygen pressure are in good agreement with a previous measurement in pure hydrogen. Therefore, depression of the surface tension by oxygen is insignificant in these measurements.

  2. Surface tension of liquid metals and alloys--recent developments.

    Science.gov (United States)

    Egry, I; Ricci, E; Novakovic, R; Ozawa, S

    2010-09-15

    Surface tension measurements are a central task in the study of surfaces and interfaces. For liquid metals, they are complicated by the high temperatures and the consequently high reactivity characterising these melts. In particular, oxidation of the liquid surface in combination with evaporation phenomena requires a stringent control of the experimental conditions, and an appropriate theoretical treatment. Recently, much progress has been made on both sides. In addition to improving the conventional sessile drop technique, new containerless methods have been developed for surface tension measurements. This paper reviews the experimental progress made in the last few years, and the theoretical framework required for modelling and understanding the relevant physico-chemical surface phenomena.

  3. Measurement of dynamic surface tension by mechanically vibrated sessile droplets

    Science.gov (United States)

    Iwata, Shuichi; Yamauchi, Satoko; Yoshitake, Yumiko; Nagumo, Ryo; Mori, Hideki; Kajiya, Tadashi

    2016-04-01

    We developed a novel method for measuring the dynamic surface tension of liquids using mechanically vibrated sessile droplets. Under continuous mechanical vibration, the shape of the deformed droplet was fitted by numerical analysis, taking into account the force balance at the drop surface and the momentum equation. The surface tension was determined by optimizing four parameters: the surface tension, the droplet's height, the radius of the droplet-substrate contact area, and the horizontal symmetrical position of the droplet. The accuracy and repeatability of the proposed method were confirmed using drops of distilled water as well as viscous aqueous glycerol solutions. The vibration frequency had no influence on surface tension in the case of pure liquids. However, for water-soluble surfactant solutions, the dynamic surface tension gradually increased with vibration frequency, which was particularly notable for low surfactant concentrations slightly below the critical micelle concentration. This frequency dependence resulted from the competition of two mechanisms at the drop surface: local surface deformation and surfactant transport towards the newly generated surface.

  4. Multiscale surface roughening of commercial purity titanium during uniaxial tension

    Energy Technology Data Exchange (ETDEWEB)

    Panin, Alexey, E-mail: pav@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation); Kazachenok, Marina, E-mail: kms@ispms.tsc.ru; Kozelskaya, Anna, E-mail: annakozelskaya@gmail.com; Sinyakova, Elena, E-mail: mea@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Lider, Andrey, E-mail: lider@tpu.ru; Sklyarova, Elena, E-mail: skea@tpu.ru [National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    The mechanisms of the surface roughening of the titanium specimens during uniaxial tension were demonstrated. By means of optical profilometry and electron backscattered diffraction it was shown that the formation of surface roughening is a multilevel process. The correlation between the density of slip in some grains, and grain rotation, and their displacement towards the free surface was investigated.

  5. Surface borehole synthesis tension deformation fracture time-space rule

    Institute of Scientific and Technical Information of China (English)

    Liu Jianzhong; Sun Haitao; Hu Qianting

    2012-01-01

    In order to release the tension and shear effect of the superjacent rock strata movement during excavation in coal mine,protect the surface borehole case from fracturing fast and make a good use of the surface borehole during goaf methane drawing,a common synthesis tension deformation fracture model was set up based on the synthesis tension effect of the rock strata,and the deformation rule of the surface borehole case with time and space was researched.The results suggest that,to reduce the deformation the surface borehole should be built between the boundary of the stope and the knee of subsidence curve.At the same time,a 3DEC simulation model and an engineering example were carried out to examine the rules of theoretical model.The result suggests that the model and the rules accord to the test and have good building and protection engineering application values to the surface borehole.

  6. Surface tension alteration on calcite, induced by ion substitution

    DEFF Research Database (Denmark)

    Sakuma, Hiroshi; Andersson, Martin Peter; Bechgaard, Klaus

    2014-01-01

    The interaction of water and organic molecules with mineral surfaces controls many processes in nature and industry. The thermodynamic property, surface tension, is usually determined from the contact angle between phases, but how does one understand the concept of surface tension at the nanoscale...... in the pore water. Incorporation of MgSO4 into calcite, which is energetically favored, decreases surface tension and releases polar oil compounds......., where particles are smaller than the smallest droplet? We investigated the energy required to exchange Mg2+ and SO4 2- from aqueous solution into calcite {10.4} surfaces using density functional theory. Mg2+ substitution for Ca2+ is favored but only when SO4 2- is also present and MgSO4 incorporates...

  7. Decay of viscous surface waves without surface tension

    CERN Document Server

    Guo, Yan

    2010-01-01

    Consider a viscous fluid of finite depth below the air. In the absence of the surface tension effect at the air-fluid interface, the long time behavior of a free surface with small amplitude has been an intriguing question since the work of Beale \\cite{beale_1}. In this monograph, we develop a new mathematical framework to resolve this question. If the free interface is horizontally infinite, we establish that it decays to a flat surface at an algebraic rate. On the other hand, if the free interface is periodic, we establish that it decays at an almost exponential rate, i.e. at an arbitrarily fast algebraic rate determined by the smallness of the data. Our framework contains several novel techniques, which include: (1) a local well-posed theory of the Navier-Stokes equations in the presence of a moving boundary; (2) a two-tier energy method that couples the boundedness of high-order energy to the decay of low-order energy, the latter of which is necessary to balance out the growth of the highest derivatives o...

  8. Why is surface tension a force parallel to the interface?

    CERN Document Server

    Marchand, Antonin; Snoeijer, Jacco H; Andreotti, Bruno

    2012-01-01

    A paperclip can float on water. Drops of mercury refuse to spread on a surface. These capillary phenomena are macroscopic manifestations of molecular interactions, and can be explained in terms of surface tension. For students, the concept of surface tension is quite challenging since the microscopic intuition is often in conflict with the common macroscopic interpretations. In this paper we address a number of conceptual questions that are often encountered when teaching capillarity. By answering these questions we provide a perspective that reconciles the macroscopic viewpoints, from thermodynamics or fluid mechanics, and the microscopic perspective from statistical physics.

  9. Surface tension driven flow in glass melts and model fluids

    Science.gov (United States)

    Mcneil, T. J.; Cole, R.; Subramanian, R. S.

    1982-01-01

    Surface tension driven flow has been investigated analytically and experimentally using an apparatus where a free column of molten glass or model fluids was supported at its top and bottom faces by solid surfaces. The glass used in the experiments was sodium diborate, and the model fluids were silicone oils. In both the model fluid and glass melt experiments, conclusive evidence was obtained to prove that the observed flow was driven primarily by surface tension forces. The experimental observations are in qualitative agreement with predictions from the theoretical model.

  10. Surface tension of highly magnetized degenerate quark matter

    CERN Document Server

    Lugones, G

    2016-01-01

    We study the surface tension of highly magnetized three flavor quark matter within the formalism of multiple reflection expansion (MRE). Quark matter is described as a mixture of free Fermi gases composed by quarks $u$, $d$, $s$ and electrons, in chemical equilibrium under weak interactions. Due to the presence of strong magnetic fields the particles' transverse motion is quantized into Landau levels, and the surface tension has a different value in the parallel and transverse directions with respect to the magnetic field. We calculate the transverse and longitudinal surface tension for different values of the magnetic field and for quark matter drops with different sizes, from a few fm to the bulk limit. For baryon number densities between $2-10$ times the nuclear saturation density, the surface tension falls in the range $2 - 20$ MeV /fm$^{2}$. The largest contribution comes from strange quarks which have a surface tension an order of magnitude larger than the one for $u$ or $d$ quarks and more than two ord...

  11. Surface tension regularizes the crack singularity of adhesion

    NARCIS (Netherlands)

    Karpitschka, Stefan; van Wijngaarden, L.; van Wijngaarden, L.; Snoeijer, Jacobus Hendrikus

    2016-01-01

    The elastic and adhesive properties of a solid surface can be quantified by indenting it with a rigid sphere. Indentation tests are classically described by the JKR-law when the solid is very stiff, while recent work highlights the importance of surface tension for exceedingly soft materials. Here

  12. Why is surface tension a force parallel to the interface?

    NARCIS (Netherlands)

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

    2011-01-01

    A paperclip can float on water. Drops of mercury do not spread on a surface. These capillary phenomena are macroscopic manifestations of molecular interactions and can be explained in terms of surface tension. We address several conceptual questions that are often encountered when teaching

  13. Surface tension of the Widom-Rowlinson model.

    Science.gov (United States)

    de Miguel, E; Almarza, N G; Jackson, G

    2007-07-21

    We consider the computation of the surface tension of the fluid-fluid interface for the Widom-Rowlinson [J. Chem. Phys. 52, 1670 (1970)] binary mixture from direct simulation of the inhomogeneous system. We make use of the standard mechanical route, in which the surface tension follows from the computation of the normal and tangential components of the pressure tensor of the system. In addition to the usual approach, which involves simulations of the inhomogeneous system in the canonical ensemble, we also consider the computation of the surface tension in an ensemble where the pressure perpendicular (normal) to the planar interface is kept fixed. Both approaches are seen to provide consistent values of the interfacial tension. The issue of the system-size dependence of the surface tension is addressed. In addition, simulations of the fluid-fluid coexistence properties of the mixture are performed in the semigrand canonical ensemble. Our results are compared with existing data of the Widom-Rowlinson mixture and are also examined in the light of the vapor-liquid equilibrium of the thermodynamically equivalent one-component penetrable sphere model.

  14. The Role of Bag Surface Tension in Color Confinement

    CERN Document Server

    Bugaev, K A

    2011-01-01

    We discuss here the novel view at the color confinement which, on the one hand, allows us to find out the surface tension coefficient of quark gluon bags and, under a plausible assumption, to determine the endpoint temperature of the QCD phase diagram, on the other hand. The present model considers the confining color tube as the cylindrical quark gluon bag with non-zero surface tension. A close inspection of the free energies of elongated cylindrical bag and the confining color tube that connects the static quark-antiquark pair allows us to find out the string tension in terms of the surface tension, thermal pressure and the bag radius. Using the derived relation it is possible to estimate the bag surface tension at zero temperature directly from the lattice QCD data and to estimate the (tri)critical endpoint temperature. In the present analysis the topological free energy of the cylindrical bag is accounted for the first time. The requirement of positive entropy density of such bags leads to negative values...

  15. Molecular simulation of the surface tension of real fluids

    CERN Document Server

    Werth, Stephan; Hasse, Hans

    2016-01-01

    Molecular models of real fluids are validated by comparing the vapor-liquid surface tension from molecular dynamics (MD) simulation to correlations of experimental data. The considered molecular models consist of up to 28 interaction sites, including Lennard-Jones sites, point charges, dipoles and quadrupoles. They represent 38 real fluids, such as ethylene oxide, sulfur dioxide, phosgene, benzene, ammonia, formaldehyde, methanol and water, and were adjusted to reproduce the saturated liquid density, vapor pressure and enthalpy of vaporization. The models were not adjusted to interfacial properties, however, so that the present MD simulations are a test of model predictions. It is found that all of the considered models overestimate the surface tension. In most cases, however, the relative deviation between the simulation results and correlations to experimental data is smaller than 20 %. This observation corroborates the outcome of our previous studies on the surface tension of 2CLJQ and 2CLJD fluids where a...

  16. A density gradient theory based method for surface tension calculations

    DEFF Research Database (Denmark)

    Liang, Xiaodong; Michelsen, Michael Locht; Kontogeorgis, Georgios

    2016-01-01

    The density gradient theory has been becoming a widely used framework for calculating surface tension, within which the same equation of state is used for the interface and bulk phases, because it is a theoretically sound, consistent and computationally affordable approach. Based on the observation...... that the optimal density path from the geometric mean density gradient theory passes the saddle point of the tangent plane distance to the bulk phases, we propose to estimate surface tension with an approximate density path profile that goes through this saddle point. The linear density gradient theory, which...... assumes linearly distributed densities between the two bulk phases, has also been investigated. Numerical problems do not occur with these density path profiles. These two approximation methods together with the full density gradient theory have been used to calculate the surface tension of various...

  17. Research of some marks contemporary hydrocarbon fuel surface tension

    Directory of Open Access Journals (Sweden)

    С.В. Бойченко

    2005-01-01

    Full Text Available  The  surface  tension  of  some  marks  domestic  and  foreign  gasoline’s  and  jet  fuels  is  investigated  depending  on  distillation. Dependences  of  surface  tension,  composition,  boiling  points  liquid  fuel  experimentally  are  received.

  18. Instantons and surface tension at a first-order transition

    Science.gov (United States)

    Gupta, Sourendu

    1994-04-01

    We study the dynamics of the first-order phase transition in the two-dimensional 15-state Potts model, both at and off equilibrium. We find that phase changes take place through nucleation in both cases, and finite volume effects are described well through an instanton computation. Thus a dynamical measurement of the surface tension is possible. We find that the order-disorder surface tension is compatible with perfect wetting. An accurate treatment of fluctuations about the instanton solution is seen to be of great importance. Current Address: Theory Group, TIFR, Homi Bhabha Road, Bombay 400005, India.

  19. Estimation of the surface tension of ocular cornea

    Science.gov (United States)

    Zhang, Xueyong; Ma, Jianguo; Lu, Rongsheng; Xia, Ruixue

    2008-12-01

    Considering the potential clinical importance, the surface tension of ocular cornea under the action of normal physiological intraocular pressure is estimated, and a novel technique and a simple mechanical model for determining the tension are also presented in this paper. An instrument embodying mainly a CCD camera, an optical staff gauge and a manometer was developed primarily to measure both the surface point displacement and intraocular pressure of the cornea. A simple theoretical model was used to characterize the tensions of the ocular corneas under the action of the intraocular pressure. Due to the difficulty in obtaining the human cornea, laboratory experiments were carried out on porcine cornea specimens. The thickness of the specimens was accurately measured by optical coherence tomography. The matrix and collagen properties within the corneal tissue were manifested in the experiment. Experimental results on porcine corneas showed that the present technique is applicable to estimate the surface tension. In the normal physiological intraocular pressure range, both meridian and circumference tensions of the porcine corneas along the radial coordinate distribute are not uniform.

  20. Surface pore tension and adsorption characteristics of polluted sediment

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Most natural sediment particles have numerous pores and a complex surface texture which facilitates their adsorption of contaminants. Particle surface structure,therefore,is an important instrumental factor in the transport of contaminants,especially in water environments. This paper reports on the results of adsorption-desorption experiments to analyze polluted sediment surface pore tension characteristics performed on samples from the bottom of Guanting Reservoir. In our analysis,the Frenkel-Halsey-Hill(FHH) equation is applied to calculate the fractal dimensions of particles to quantify the surface roughness and pore tension characteristics. The results show that the surface fractal dimensions of sediment particle surfaces normally measure from 2.6 to 2.85. The volume of pores smaller than 10 nm changes significantly after being contaminated with pollutants and the fractal dimension decreases because the pores adsorb the contaminants.

  1. New thermodynamics for evaluating the surface-phase enrichment in the lower surface tension component.

    Science.gov (United States)

    Santos, M Soledade C S; Reis, João Carlos R

    2014-09-15

    Regarding the surface phase of liquid mixtures as a thermodynamic phase, ideal surface phases are designed so that at fixed bulk-phase composition, real and ideal surface phases have the same chemical composition and identical limiting slopes for the dependence of surface tension on mole fraction. Standard chemical potentials are introduced for surface phase components, and quasi-exact expressions are worked out to compute ideal surface tensions and surface-phase compositions of real liquid mixtures. Guidelines for choosing molecular models to estimate the molar surface area of pure constituents are given. Ideal and excess surface tensions are calculated by using literature data for aqueous ethanol solutions at 298 K. These results show treatment based on Butler's equations grossly overestimate predicted surface tensions, thus leading to lower ethanol content in the surface phase. These inaccuracies are ascribed to the use of molar surface areas in model equations that are too small.

  2. Surface tension effects on immersed electrosprays

    CERN Document Server

    Marin, Alvaro G; Barrero, Antonio

    2012-01-01

    Electrosprays are a powerful technique to generate charged micro/nanodroplets. In the last century, the technique received extensive study and successful applications, including a Nobel price in Chemistry. However, nowadays its use in microfluidic devices is still limited mainly due to a lack of knowledge of the phenomenon when the dispersing fluid is immersed in another inmiscible liquid. The "immersed electrosprays" share almost identical properties as their counterparts in air. Things however change when surface active agents are added to the host liquid, which are normally used in lab-on-chip applications to stabilize the generated emulsions. In this work, we review the main properties of the immersed electrosprays in liquid baths with no surfactant, and we methodically study the behavior of the system for increasing surfactant concentrations. The different regimes found are then analyzed and compared with both classical and more recent experimental, theoretical and numerical studies. A very rich phenomen...

  3. Three-Dimensional Smoothed Particle Hydrodynamics Simulation for Liquid Droplet with Surface Tension

    OpenAIRE

    Terissa, Hanifa; Barecasco, Agra; Naa, Christian Fredy

    2013-01-01

    We provide a basic method of Smoothed Particle Hydrodynamics (SPH) to simulate liquid droplet with surface tension in three dimensions. Liquid droplet is a simple case for surface tension modeling. Surface tension works only on fluid surface. In SPH method, we simply apply the surface tension on the boundary particles of liquid. The particle on the 3D boundary was detected dynamically using Free-Surface Detection algorithm. The normal vector and curvature of the boundary surface were calculat...

  4. Dynamic surface tension of surfactant TA: experiments and theory.

    Science.gov (United States)

    Otis, D R; Ingenito, E P; Kamm, R D; Johnson, M

    1994-12-01

    A bubble surfactometer was used to measure the surface tension of an aqueous suspension of surfactant TA as a function of bubble area over a range of cycling rates and surfactant bulk concentrations. Results of the surface tension-interfacial area loops exhibited a rich variety of phenomena, the character of which varied systematically with frequency and bulk concentration. A model was developed to interpret and explain these data and for use in describing the dynamics of surface layers under more general circumstances. Surfactant was modeled as a single component with surface tension taken to depend on only the interfacial surfactant concentration. Two distinct mechanisms were considered for the exchange of surfactant between the bulk phase and interface. The first is described by a simple kinetic relationship for adsorption and desorption that pertains only when the interfacial concentration is below its maximum equilibrium value. The second mechanism is "squeeze-out" by which surfactant molecules are expelled from an interface compressed past a maximum packing state. The model provided good agreement with experimental measurements for cycling rates from 1 to 100 cycles/min and for bulk concentrations between 0.0073 and 7.3 mg/ml.

  5. Surface tension dominates insect flight on fluid interfaces.

    Science.gov (United States)

    Mukundarajan, Haripriya; Bardon, Thibaut C; Kim, Dong Hyun; Prakash, Manu

    2016-03-01

    Flight on the 2D air-water interface, with body weight supported by surface tension, is a unique locomotion strategy well adapted for the environmental niche on the surface of water. Although previously described in aquatic insects like stoneflies, the biomechanics of interfacial flight has never been analysed. Here, we report interfacial flight as an adapted behaviour in waterlily beetles (Galerucella nymphaeae) which are also dexterous airborne fliers. We present the first quantitative biomechanical model of interfacial flight in insects, uncovering an intricate interplay of capillary, aerodynamic and neuromuscular forces. We show that waterlily beetles use their tarsal claws to attach themselves to the interface, via a fluid contact line pinned at the claw. We investigate the kinematics of interfacial flight trajectories using high-speed imaging and construct a mathematical model describing the flight dynamics. Our results show that non-linear surface tension forces make interfacial flight energetically expensive compared with airborne flight at the relatively high speeds characteristic of waterlily beetles, and cause chaotic dynamics to arise naturally in these regimes. We identify the crucial roles of capillary-gravity wave drag and oscillatory surface tension forces which dominate interfacial flight, showing that the air-water interface presents a radically modified force landscape for flapping wing flight compared with air.

  6. Effects of Induced Surface Tension in Nuclear and Hadron Matter

    CERN Document Server

    Sagun, V V; Ivanytskyi, A I; Oliinychenko, D R; Mishustin, I N

    2016-01-01

    Short range particle repulsion is rather important property of the hadronic and nuclear matter equations of state. We present a novel equation of state which is based on the virial expansion for the multicomponent mixtures with hard-core repulsion. In addition to the hard-core repulsion taken into account by the proper volumes of particles, this equation of state explicitly contains the surface tension which is induced by another part of the hard-core repulsion between particles. At high densities the induced surface tension vanishes and the excluded volume treatment of hard-core repulsion is switched to its proper volume treatment. Possible applications of this equation of state to a description of hadronic multiplicities measured in A+A collisions, to an investigation of the nuclear matter phase diagram properties and to the neutron star interior modeling are discussed.

  7. Effects of Induced Surface Tension in Nuclear and Hadron Matter

    Directory of Open Access Journals (Sweden)

    Sagun V.V.

    2017-01-01

    Full Text Available Short range particle repulsion is rather important property of the hadronic and nuclear matter equations of state. We present a novel equation of state which is based on the virial expansion for the multicomponent mixtures with hard-core repulsion. In addition to the hard-core repulsion taken into account by the proper volumes of particles, this equation of state explicitly contains the surface tension which is induced by another part of the hard-core repulsion between particles. At high densities the induced surface tension vanishes and the excluded volume treatment of hard-core repulsion is switched to its proper volume treatment. Possible applications of this equation of state to a description of hadronic multiplicities measured in A+A collisions, to an investigation of the nuclear matter phase diagram properties and to the neutron star interior modeling are discussed.

  8. Comparing contact angle measurements and surface tension assessments of solid surfaces.

    Science.gov (United States)

    Cwikel, Dory; Zhao, Qi; Liu, Chen; Su, Xueju; Marmur, Abraham

    2010-10-05

    Four types of contact angles (receding, most stable, advancing, and "static") were measured by two independent laboratories for a large number of solid surfaces, spanning a large range of surface tensions. It is shown that the most stable contact angle, which is theoretically required for calculating the Young contact angle, is a practical, useful tool for wettability characterization of solid surfaces. In addition, it is shown that the experimentally measured most stable contact angle may not always be approximated by an average angle calculated from the advancing and receding contact angles. The "static" CA is shown in many cases to be very different from the most stable one. The measured contact angles were used for calculating the surface tensions of the solid samples by five methods. Meaningful differences exist among the surface tensions calculated using four previously known methods (Owens-Wendt, Wu, acid-base, and equation of state). A recently developed, Gibbsian-based correlation between interfacial tensions and individual surface tensions was used to calculate the surface tensions of the solid surfaces from the most stable contact angle of water. This calculation yielded in most cases higher values than calculated with the other four methods. On the basis of some low surface energy samples, the higher values appear to be justified.

  9. Transparent, Superhydrophobic Surface with Varied Surface Tension Responsiveness in Wettability Based on Tunable Porous Silica Structure for Gauging Liquid Surface Tension.

    Science.gov (United States)

    Wang, Yan; Zhu, Yingjie; Zhang, Chunyang; Li, Jun; Guan, Zisheng

    2017-02-01

    Any solid surface can spontaneously exhibit variational wettability toward liquids with varied surface tension (γ). However, this correspondence has seldom been proposed or used on an artificial superhydrophobic surface, which should be more remarkable and peculiar. Herein, we fabricated robust, transparent superhydrophobic surfaces utilizing acid- and base-catalyzed silica (AC- and BC-silica) particles combined with candle soot template for structural construction and the CVD process for chemical modification. Three types of porous silica structures were devised, which presented distinctive surface tension responsiveness in wettability. Interestingly, all types of surfaces (i.e., AC-, AC/BC-, and BC-silica) show high repellence to high surface tension liquid (γ > 35 mN/m), and small differences are observed. With decreasing γ of the ethanol-water mixtures (γ superhydrophobic surfaces.

  10. Surface water waves due to an oscillatory wavemaker in the presence of surface tension

    Directory of Open Access Journals (Sweden)

    B. N. Mandal

    1992-01-01

    Full Text Available The initial value problem of generation of surface water waves by a harmonically oscillating plane vertical wavemaker in an infinite incompressible fluid under the action of gravity and surface tension is investigated. In the asymptotic evaluation of the free surface depression for large time and distance, the contribution to the integral by stationary phase method gives rise to transient component of the free surface depression while the contribution from the poles give rise to steady state component. It is observed that the presence of surface tension sometimes changes the qualitative nature of the transient component of free surface depression.

  11. Effects of varying interfacial surface tension on macroscopic polymer lenses

    Science.gov (United States)

    Zimmerman, Charlotte; White, Mason; Baylor, Martha-Elizabeth

    2015-09-01

    We investigate macroscopic polymer lenses (0.5- to 2.5-cm diameter) fabricated by dropping hydrophobic photocurable resin onto the surface of various hydrophilic liquid surfaces. Due to the intermolecular forces along the interface between the two liquids, a lens shape is formed. We find that we can vary the lens geometry by changing the region over which the resin is allowed to spread and the surface tension of the substrate to produce lenses with theoretically determined focal lengths ranging from 5 to 25 mm. These effects are varied by changing the container width, substrate composition, and substrate temperature. We present data for five different variants, demonstrating that we can control the lens dimensions for polymer lens applications that require high surface quality.

  12. On the surface tension of neutron star matter

    CERN Document Server

    Rueda, Jorge A; Wu, Yuan-Bin; Xue, She-Sheng

    2013-01-01

    It has been recently shown that taking into account strong, weak, electromagnetic, and gravitational interactions, and fulfilling the global charge neutrality of the system, a transition layer will happen between the core and crust of neutron stars, at the nuclear saturation density. We use relativistic mean field theory together with the Thomas-Fermi approximation to study the detailed structure of this transition layer and calculate its surface and Coulomb energy. We find that the surface tension is proportional to a power-law function of the baryon number density in the core bulk region. We also analyze the influence of the gravitational field and the electron component on the structure of the transition layer and the value of the surface tension to compare and contrast with known phenomenological results in nuclear physics. Based on the above results we study the instability against Bohr-Wheeler surface deformations in the case of neutron stars obeying global charge neutrality. Assuming the core-crust tra...

  13. Surface tension and quasi-emulsion of cavitation bubble cloud.

    Science.gov (United States)

    Bai, Lixin; Chen, Xiaoguang; Zhu, Gang; Xu, Weilin; Lin, Weijun; Wu, Pengfei; Li, Chao; Xu, Delong; Yan, Jiuchun

    2017-03-01

    A quasi-emulsion phenomenon of cavitation structure in a thin liquid layer (the thin liquid layer is trapped between a radiating surface and a hard reflector) is investigated experimentally with high-speed photography. The transformation from cloud-in-water (c/w) emulsion to water-in-cloud (w/c) emulsion is related to the increase of cavitation bubble cloud. The acoustic field in the thin liquid layer is analyzed. It is found that the liquid region has higher acoustic pressure than the cloud region. The bubbles are pushed from liquid region to cloud region by the primary Bjerknes forces. The rate of change of CSF increased with the increase of CSF. The cavitation bubbles on the surface of cavitation cloud are attracted by the cavitation bubbles inside the cloud due to secondary Bjerknes forces. The existence of surface tension on the interface of liquid region and cloud region is proved. The formation mechanism of disc-shaped liquid region and cloud region are analysed by surface tension and incompressibility of cavitation bubble cloud. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Steady needle growth with 3-D anisotropic surface tension

    Institute of Scientific and Technical Information of China (English)

    Xiao-jun CHEN; Yong-qiang CHEN; Jian-pu XU; Jian-jun XU

    2008-01-01

    The effect of the anisotropic interracial en-ergy on dendritic growth has been an important sub-ject, and has preoccupied many researchers in the field of materials science and condensed matter physics. The present paper is dedicated to the study of the effect of full 3-D anisotropic Surface tension on the steady state solution of dendritic growth. We obtain the analytical form of the first order approximation solution in the reg-ular asymptotic expansion around the Ivantsov's nee-dle growth solution, which extends the steady needle growth solution of the system with isotropic surface ten-sion obtained by Xu and Yu (J. J. Xu and D. S. Yu, J. Cryst. Growth, 1998, 187: 314; J. J. Xu, Interfa-cial Wave Theory of Pattern Formation: Selection of Dendrite Growth and Viscous Fingering in a Hele-Shaw Flow, Berlin: Springer-Verlag, 1997).The solution is expanded in the general Laguerre se-ries in any finite region around the needle-tip, and it is also expanded in a power series in the far field behind the tip. Both solutions are then numerically matched in the intermediate region. Based on this global valid solution, the dependence of Peclet number Pe and the interface's morphology on the anisotropy parameter of surface ten-sion as well as other physical parameters involved are determined. On the basis of this global valid solution, we explore the effect of the anisotropy parameter on the Peclet number of growth, as well as the morphology of the interface.

  15. Adhesion energy, surface traction and surface tension in liquid xenon

    Indian Academy of Sciences (India)

    B Mathew; G A Adebayo

    2011-12-01

    We calculated the adhesion energy, the surface traction and the surface energy of liquid xenon using molecular dynamics (MD) simulation. The value of the adhesion energy for liquid xenon at a reduced density of 0.630 was found to be 0.591 J/m2 and the surface traction has a peak at = 3.32 Å. It was observed that the attraction of the molecules in the liquid surface which produces a resistance to penetration decreases with temperature. This may be attributed to the greater average separation of molecules at higher temperature.

  16. Drop formation by thermal fluctuations at an ultralow surface tension.

    Science.gov (United States)

    Hennequin, Y; Aarts, D G A L; van der Wiel, J H; Wegdam, G; Eggers, J; Lekkerkerker, H N W; Bonn, Daniel

    2006-12-15

    We present experimental evidence that drop breakup is caused by thermal noise in a system with a surface tension that is more than 10(6) times smaller than that of water. We observe that at very small scales classical hydrodynamics breaks down and the characteristic signatures of pinch-off due to thermal noise are observed. Surprisingly, the noise makes the drop size distribution more uniform, by suppressing the formation of satellite droplets of the smallest sizes. The crossover between deterministic hydrodynamic motion and stochastic thermally driven motion has repercussions for our understanding of small-scale hydrodynamics, important in many problems such as micro- or nanofluidics and interfacial singularities.

  17. Experiments on buoyancy and surface tension following Galileo Galilei

    Science.gov (United States)

    Straulino, S.; Gambi, C. M. C.; Righini, A.

    2011-01-01

    We analyze passages of Galileo's writings on aspects of floating. Galileo encountered peculiar effects such as the "floating" of light objects made of dense material and the creation of large drops of water that were difficult to explain because they are related to our current understanding of surface tension. Even though Galileo could not understand the phenomenon, his proposed explanations and experiments are interesting from an educational point of view. We replicate the experiment on water and wine that was described by Galileo in his Two New Sciences.

  18. Surface tension propulsion of fungal spores by use of microdroplets

    CERN Document Server

    Noblin, Xavier; Dumais, Jacques

    2010-01-01

    Many edible mushrooms eject their spores (about 10 microns in size) at high speed (about 1 m/s) using surface tension forces in a few microseconds. Basically the coalescence of a droplet with the spore generates the necessary momentum to eject the spore. We have detailed this mechanism in \\cite{noblin2}. In this article, we give some details about the high speed movies (up to 250000 fps) of mushrooms' spores ejection attached to this submission. This video was submitted as part of the Gallery of Fluid Motion 2010 which is showcase of fluid dynamics videos.

  19. Surface tension driven shaping of adhesive microfluidic channel walls

    DEFF Research Database (Denmark)

    Janting, Jakob; Storm, Elisabeth K.; Geschke, Oliver

    2005-01-01

    The feasibility of making microfluidic channels with different wall geometries using adjacent lines of dispensed adhesive between substrates has been studied. Important parameters for the geometry have been identified to be: surface tension (adhesive / substrates), adhesive viscosity / thixotropy......, line height and distance, and temperature. Focus of the work has been on predicting the equilibrium geometries with FEM simulations using as input measured adhesive wetting angles, different adhesive line distances and height. The studied substrates are glass microscope slides, PEEK and PMMA....... The studied adhesives are DYMAX 9-20318-F, 3070, 9001 version 3.5, and Sylgard 184 PDMS....

  20. Using surface tension measurement in applications; Oberflaechenspannungsmesstechnik fuer den Prozesseinsatz

    Energy Technology Data Exchange (ETDEWEB)

    Haberland, R.; Krause, W. [SITA Messtechnik GmbH, Gostritzer Strasse 61-63, 01217 Dresden (Germany)

    2003-07-01

    When cleaning surfaces it is crucial for the process stability that the optimum surfactant concentration is maintained. The concentration of free surfactants can be measured by determining the surface tension. SITA Messtechnik has developed an innovative sensor based on the bubble pressure method. This sensor makes it possible to continuously measure surface tension with a high reliability. With this application for monitoring cleaning baths the potential to save money arises in regard to the use of raw materials, waste disposal and the costs resulting from undiscovered production failures. (Abstract Copyright [2003], Wiley Periodicals, Inc.) [German] Bei der Reinigung von Oberflaechen ist das Einhalten der optimalen Tensidkonzentration fuer die Prozesssicherheit entscheidend. Die Konzentration der freien Tenside ist messbar, indem die Oberflaechenspannung erfasst wird. Die SITA Messtechnik GmbH hat einen neuartigen Sensor auf der Basis der Blasendifferenzdruckmethode entwickelt, der eine kontinuierliche Messung der Oberflaechenspannung bei hoher Standzeit ermoeglicht. Mit dessen Anwendung zum Ueberwachen von Reinigungsbaedern ergeben sich Einsparpotentiale hinsichtlich Rohstoffeinsatz, Entsorgung und Fehlerfolgekosten. (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  1. Surface Tension of Ab Initio Liquid Water at the Water-Air Interface

    CERN Document Server

    Nagata, Yuki; Bonn, Mischa; Kühne, Thomas D

    2016-01-01

    We report calculations of the surface tension of the water-air interface using ab initio molecular dynamics (AIMD) simulations. We investigate the simulation cell size dependence of the surface tension of water from force field molecular dynamics (MD) simulations, which show that the calculated surface tension increases with increasing simulation cell size, thereby illustrating that a correction for finite size effects is required for the small system used in the AIMD simulation. The AIMD simulations reveal that the double-{\\xi} basis set overestimates the experimentally measured surface tension due to the Pulay stress, while the triple and quadruple-{\\xi} basis sets give similar results. We further demonstrate that the van der Waals corrections critically affect the surface tension. AIMD simulations without the van der Waals correction substantially underestimate the surface tension, while van der Waals correction with the Grimme's D2 technique results in the value for the surface tension that is too high. T...

  2. Functional Design and Qualification of Surface Tension Propellant Tanks

    Science.gov (United States)

    Figus, C.; Haddad, D.; Ounougha, L.; Autric, J.

    2004-10-01

    During two decades, EADS Astrium has designed and qualified the surface tension device used in the propellant tanks equipping the Eurostar telecommunication satellites platforms. Recent re- orbiting phases of Eurostar E2000 satellites, have allowed to validate those designs and to graveyard the spacecraft with less than 1 kg of propellant left per tank. Moreover, with the emergence of new powerful satellites with full chemical or mixed chemical-plasma propulsion subsystems, EADS Astrium has designed a new larger and improved surface tension propellant tank. Such challenging performances require analyses, and tests in order to assess and confirm the predicted performances. The present article shows the recent development of a new enlarged Eurostar E3000 propellant tanks for Eurostar 3000 satellites and presents the main functional analyses and neutral buoyancy tests results obtained for this new propellant tank These last two years, have contributed to improve this background with the successful graveyard of the first Eurostar spacecraft with less than 1 kg of liquid propellant per tank at the end of the manoeuvre. Moreover, a new enlarged E3000 propellant tank has been designed and qualified in order to cope with the future 12 kW telecom spacecraft applications. This tank designed by EADS-ASTRIUM, is manufactured by EADS-Space transportation. This paper presents the performances and tests results obtained on this new propellant tank.

  3. The surface tension effect on viscous liquid spreading along a superhydrophobic surface

    Science.gov (United States)

    Aksenov, A. V.; Sudarikova, A. D.; Chicherin, I. S.

    2017-01-01

    Within the Stokes film approximation, unsteady plane-parallel spreading of a thin layer of a heavy viscous fluid along a horizontal superhydrophobic surface is studied. The forced spreading regimes induced by the mass supply are considered. Plane-parallel flow along the principal direction of the slip tensor of the superhydrophobic surface is studied in case that the corresponding slip tensor component is a power function of the spatial coordinate. An evolution equation for the film thickness is derived taking into account surface tension that is dependent on the spatial coordinate. The group classification problem is solved. Self-similar and invariant solutions are constructed for power and exponent time dependences on mass supply respectively at a special form of the surface tension coefficient. Surface tension is shown to have a significant influence on the character of the liquid spreading.

  4. Effect of surface tension on the mode selection of vertically excited surface waves in a circular cylindrical vessel

    Institute of Scientific and Technical Information of China (English)

    Jian Yong-Jun; E Xue-Quan; Zhang Jie; Meng Jun-Min

    2004-01-01

    Singular perturbation theory of two-time-scale expansions was developed in inviscid fluids to investigate patternforming, structure of the single surface standing wave, and its evolution with time in a circular cylindrical vessel subject to a vertical oscillation. A nonlinear slowly varying complex amplitude equation, which involves a cubic nonlinear term,an external excitation and the influence of surface tension, was derived from the potential flow equation. Surface tension was introduced by the boundary condition of the free surface in an ideal and incompressible fluid. The results show that when forced frequency is low, the effect of surface tension on the mode selection of surface waves is not important.However, when the forced frequency is high, the surface tension cannot be neglected. This manifests that the function of surface tension is to cause the free surface to return to its equilibrium configuration. In addition, the effect of surface tension seems to make the theoretical results much closer to experimental results.

  5. Size dependence of the surface tension of a free surface of an isotropic fluid

    Science.gov (United States)

    Burian, Sergii; Isaiev, Mykola; Termentzidis, Konstantinos; Sysoev, Vladimir; Bulavin, Leonid

    2017-06-01

    We report on the size dependence of the surface tension of a free surface of an isotropic fluid. The size dependence of the surface tension is evaluated based on the Gibbs-Tolman-Koenig-Buff equation for positive and negative values of curvatures and the Tolman lengths. For all combinations of positive and negative signs of curvature and the Tolman length, we succeed to have a continuous function, avoiding the existing discontinuity at zero curvature (flat interfaces). As an example, a water droplet in the thermodynamical equilibrium with the vapor is analyzed in detail. The size dependence of the surface tension and the Tolman length are evaluated with the use of experimental data of the International Association for the Properties of Water and Steam. The evaluated Tolman length of our approach is in good agreement with molecular dynamics and experimental data.

  6. Surface tension and reactive wetting in solder connections

    Energy Technology Data Exchange (ETDEWEB)

    Wedi, Andre; Schmitz, Guido [Institut fuer Materialphysik, Westf. Wilhelms-Universitaet, Wilhelm-Klemm-Strasse 10, 48149 Muenster (Germany)

    2011-07-01

    Wetting is an important pre-requisite of a reliable solder connection. However, it is only an indirect measure for the important specific energy of the reactive interface between solder and base metallization. In order to quantify this energy, we measured wetting angles of solder drops as well as surface tension of SnPb solders under systematic variation of composition and gaseous flux at different reflow temperatures. For the latter, we used the sessile drop method placing a solder drop on a glas substrate. From the two independent data sets, the important energy of the reactive interface is evaluated based on Young's equation. Remarkably, although both, the tension between the solder and flux and the wetting angle, reveal significant dependence on solder composition. So the adhesion energy reveals distinguished plateaus which are related to different reaction products in contact to the solder. TEM analysis and calculations of phase stabilities show that there is no Cu6Sn5 for high lead concentrations. The experiments confirm a model of reactive wetting by Eustathopoulos.

  7. Three-Dimensional Smoothed Particle Hydrodynamics Simulation for Liquid Droplet with Surface Tension

    CERN Document Server

    Terissa, Hanifa; Naa, Christian Fredy

    2013-01-01

    We provide a basic method of Smoothed Particle Hydrodynamics (SPH) to simulate liquid droplet with surface tension in three dimensions. Liquid droplet is a simple case for surface tension modeling. Surface tension works only on fluid surface. In SPH method, we simply apply the surface tension on the boundary particles of liquid. The particle on the 3D boundary was detected dynamically using Free-Surface Detection algorithm. The normal vector and curvature of the boundary surface were calculated simultaneously with 3D boundary surface reconstruction using Moving Least-Squares (MLS) method. Before the reconstruction, the coordinate system was transformed into a local coordinate system. Afterwards, the surface tension force which depends on curvature of the surface, was calculated and applied on the boundary particles of the droplet. We present the simulation result of droplet motion with gravity force. By using the basic method of SPH for fluid modeling, and a combination of 3D Free-Surface Detection algorithm ...

  8. Surface tension isotherms of the dioxane-acetone-water and glycerol-ethanol-water ternary systems

    Science.gov (United States)

    Dzhambulatov, R. S.; Dadashev, R. Kh.; Elimkhanov, D. Z.; Dadashev, I. N.

    2016-10-01

    The results of the experimental and theoretical studies of the concentration dependence of surface tension of aqueous solutions of the 1,4-dioxane-acetone-water and glycerol-ethanol-water ternary systems were given. The studies were performed by the hanging-drop method on a DSA100 tensiometer. The maximum error of surface tension was 1%. The theoretical models for calculating the surface tension of the ternary systems of organic solutions were analyzed.

  9. Structures and surface tensions of fluids near solid surfaces: an integral equation theory study.

    Science.gov (United States)

    Xu, Mengjin; Zhang, Chen; Du, Zhongjie; Mi, Jianguo

    2012-06-07

    In this work, integral equation theory is extended to describe the structures and surface tensions of confined fluids. To improve the accuracy of the equation, a bridge function based on the fundamental measure theory is introduced. The density profiles of the confined Lennard-Jones fluids and water are calculated, which are in good agreement with simulation data. On the basis of these density profiles, the grand potentials are then calculated using the density functional approach, and the corresponding surface tensions are predicted, which reproduce the simulation data well. In particular, the contact angles of water in contact with both hydrophilic and hydrophobic walls are evaluated.

  10. Calculation of Surface Tensions of Polar Mixtures with a Simplified Gradient Theory Model

    DEFF Research Database (Denmark)

    Zuo, You-Xiang; Stenby, Erling Halfdan

    1996-01-01

    Key Words: Thermodynamics, Simplified Gradient Theory, Surface Tension, Equation of state, Influence Parameter.In this work, assuming that the number densities of each component in a mixture across the interface between the coexisting vapor and liquid phases are linearly distributed, we developed...... surface tensions of 34 binary mixtures with an overall average absolute deviation of 3.46%. The results show good agreement between the predicted and experimental surface tensions. Next, the SGT model was applied to correlate surface tensions of binary mixtures containing alcohols, water or/and glycerol...

  11. Onset of initial planar instability with surface-tension anisotropy during directional solidification.

    Science.gov (United States)

    Wang, Zhijun; Wang, Jincheng; Yang, Gencang

    2009-11-01

    A simple model is presented to describe the variation of the onset of the initial planar instability with surface tension anisotropy during directional solidification. The effect of surface-tension anisotropy on the incubation time and the initial average wavelength of planar instability are predicted by the simple model quantitatively, which are also verified by phase field simulation. Investigation results reveal that surface-tension anisotropy is one of important factors in the dynamic process of planar instability. The contribution of surface-tension anisotropy to the tilting modulation is also analyzed by comparing the results from the present simple model with those from phase field simulation.

  12. Surface tension of polymer melts - experimental investigations of its effect on polymer-polymer adhesion

    DEFF Research Database (Denmark)

    Jankova Atanasova, Katja; Islam, Mohammad Aminul; Hansen, Hans Nørgaard

    The surface tension of polymer melts is important for the bond strength of two component polymer parts through their roles in the process of wetting, adsorption and adhesion. This investigation deals with the influence of the melt surface tension and substrate surface energy on the polymer...

  13. Tensioned Fabric Structures with Surface in the Form of Chen-Gackstatter

    Directory of Open Access Journals (Sweden)

    Yee Hooi Min

    2016-01-01

    Full Text Available Form-finding has to be carried out for tensioned fabric structure in order to determine the initial equilibrium shape under prescribed support condition and prestress pattern. Tensioned fabric structures are normally designed to be in the form of equal tensioned surface. Tensioned fabric structure is highly suited to be used for realizing surfaces of complex or new forms. However, research study on a new form as a tensioned fabric structure has not attracted much attention. Another source of inspiration minimal surface which could be adopted as form for tensioned fabric structure is very crucial. The aim of this study is to propose initial equilibrium shape of tensioned fabric structures in the form of Chen-Gackstatter. Computational form-finding using nonlinear analysis method is used to determine the Chen-Gackstatter form of uniformly stressed surfaces. A tensioned fabric structure must curve equally in opposite directions to give the resulting surface a three dimensional stability. In an anticlastic doubly curved surface, the sum of all positive and all negative curvatures is zero. This study provides an alternative choice for structural designer to consider the Chen-Gackstatter applied in tensioned fabric structures. The results on factors affecting initial equilibrium shape can serve as a reference for proper selection of surface parameter for achieving a structurally viable surface.

  14. Surface tension of molten Ni-(Cr, Co, W) alloys and segregation of elements

    Institute of Scientific and Technical Information of China (English)

    XIAO Feng; LIU Lan-xiao; YANG Ren-hui; ZHAO Hong-kai; FANG Liang; ZHANG Chi

    2008-01-01

    Surface tension of molten Ni-(Cr, Co, W) alloys was measured at the temperature of 1 773-1 873 K in an Ar+3%H2 atmosphere using an improved sessile drop method. The segregation of Cr, Co and W in alloy was calculated and analyzed using Butler's equation. The results show a good agreement between measured and calculated data. The surface tension of molten Ni-(Cr,Co, W) alloys decreases with increasing temperature. In Ni-(Cr, Co, W) alloys, the element with lower surface tension tends to segregate on the surface of molten alloy while that with higher surface tension tends to segregate inside of the molten alloy. The larger the differences in surface tension, atom radius and electron configuration between solvent and solute are, the more significant the segregation is. As a result, Ni segregates onto the surface and Co and W segregate inside the alloys.

  15. Survismeter, 3-in-1 Instrument for Simultaneous Measurements of Surface Tension, Inter Facial Tension (IFT and Viscosity

    Directory of Open Access Journals (Sweden)

    Man Singh

    2007-12-01

    Full Text Available The article presents Inter Facial Tension (IFT (ift, N m-1 of benzene-water; surface tensions (, N m-1 and viscosities (, N s m-2 of ethanol, glycerol, ethyl acetate, n-hexane, diethyl ether, chloroform, benzene, carbon tetrachloride [CCl4], formic acid, measured with Survismeter with ± 1.1x10-5 N m-1, ± 1.3x10-5 N m-1 and ± 1.1x10-6 N s m-2 accuracies respectively. Also the surface tension and viscosities of carboxymethylcellulose (CMC, dodecylbenzenesulfonicacid (DBSA and tetramethylammoniumhydroxide (TMAH in aqueous media have been measured with survismeter at 298.15 K. IFT of water and benzene interface was determined with survismeter. The survismeter saves resources, user’s efforts and infrastructure more than 80 % as compared to usual methods and prevents 80% disposal of materials to environment. It very accurately measures surface tension and IFT of volatile and poisonous liquids at any desired temperatures as liquids are jacked (jacketed in closed glass made bulbs.

  16. Mapping surface tension induced menisci with application to tensiometry and refractometry.

    Science.gov (United States)

    Mishra, Avanish; Kulkarni, Varun; Khor, Jian-Wei; Wereley, Steve

    2015-07-28

    In this work, we discuss an optical method for measuring surface tension induced menisci. The principle of measurement is based upon the change in the background pattern produced by the curvature of the meniscus acting as a lens. We measure the meniscus profile over an inclined glass plate and utilize the measured meniscus for estimation of surface tension and refractive index.

  17. Prediction of viscosities and surface tensions of fuels using a new corresponding states model

    DEFF Research Database (Denmark)

    Queimada, A.J.; Rolo, L.I.; Caco, A.I.

    2006-01-01

    While some properties of diesels are cheap, easy and fast to measure, such as densities, others such as surface tensions and viscosities are expensive and time consuming. A new approach that uses some basic information such as densities to predict viscosities and surface tensions is here proposed...

  18. The influence of gradients in surface tension on the mass transfer in gas liquid systems

    NARCIS (Netherlands)

    Klooster, Hubertus Willem van der

    1978-01-01

    In this investigation attention has been paid to the influence of surface tensions gradients on the performance of a packed column. From earlier investigations it is known that surface tensions have a considerable influence on the magnitude of the effective interfacial area. The work presented here

  19. Criticality and surface tension in rotating horizon thermodynamics

    Science.gov (United States)

    Hansen, Devin; Kubizňák, David; Mann, Robert B.

    2016-08-01

    We study a modified horizon thermodynamics and the associated criticality for rotating black hole spacetimes. Namely, we show that under a virtual displacement of the black hole horizon accompanied by an independent variation of the rotation parameter, the radial Einstein equation takes a form of a ‘cohomogeneity two’ horizon first law, δ E=Tδ S+{{Ω }}δ J-σ δ A, where E and J are the horizon energy (an analogue of the Misner-Sharp mass) and the horizon angular momentum, Ω is the horizon angular velocity, A is the horizon area, and σ is the surface tension induced by the matter fields. For fixed angular momentum, the above equation simplifies and the more familiar (cohomogeneity one) horizon first law δ E=Tδ S-Pδ V is obtained, where P is the pressure of matter fields and V is the horizon volume. A universal equation of state is obtained in each case and the corresponding critical behavior is studied.

  20. Criticality and Surface Tension in Rotating Horizon Thermodynamics

    CERN Document Server

    Hansen, Devin; Mann, Robert B

    2016-01-01

    We study a modified horizon thermodynamics and the associated criticality for rotating black hole spacetimes. Namely, we show that under a virtual displacement of the black hole horizon accompanied by an independent variation of the rotation parameter, the radial Einstein equation takes a form of a "cohomogeneity two" horizon first law, $dE=TdS+\\Omega dJ-\\sigma dA$, where $E$ and $J$ are the horizon energy (an analogue of the Misner-Sharp mass) and the horizon angular momentum, $\\Omega$ is the horizon angular velocity, $A$ is the horizon area, and $\\sigma$ is the surface tension induced by the matter fields. For fixed angular momentum, the above equation simplifies and the more familiar (cohomogeneity one) horizon first law $dE=TdS-PdV$ is obtained, where $P$ is the pressure of matter fields and $V$ is the horizon volume. A universal equation of state is obtained in each case and the corresponding critical behavior is studied.

  1. Effects of alternative electromagnetic field on surface tension and filling ability of molten metal

    Institute of Scientific and Technical Information of China (English)

    HE Hong-liang; KANG Fu-wei; WANG Li-ping

    2005-01-01

    Surface tension and filling ability of molten metal play an important role on the shaping of the molten metal. The surface tension was calculated from wetting angles of the molten metal by the sessile drop method. The specimen for filling ability was designed and the filling ability experiments under the alternative electromagnetic field were performed. The results show that the intensity and frequency of the alternative electromagnetic field have significant effects on the surface tension of the molten metal. The surface tension of Al-6%Si alloy decreases with increasing the intensity of the electromagnetic field. For pure Sn, the surface tension decreases gradually when the frequency of electromagnetic field is reduced. The filling ability is improved by applying the alternative electromagnetic field.

  2. Thermodynamic Modeling of Surface Tension of Aqueous Electrolyte Solution by Competitive Adsorption Model

    Directory of Open Access Journals (Sweden)

    Mohamad Javad Kamali

    2015-01-01

    Full Text Available Thermodynamic modeling of surface tension of different electrolyte systems in presence of gas phase is studied. Using the solid-liquid equilibrium, Langmuir gas-solid adsorption, and ENRTL activity coefficient model, the surface tension of electrolyte solutions is calculated. The new model has two adjustable parameters which could be determined by fitting the experimental surface tension of binary aqueous electrolyte solution in single temperature. Then the values of surface tension for other temperatures in binary and ternary system of aqueous electrolyte solution are predicted. The average absolute deviations for calculation of surface tension of binary and mixed electrolyte systems by new model are 1.98 and 1.70%, respectively.

  3. Molecular modelling and simulation of the surface tension of real quadrupolar fluids

    CERN Document Server

    Werth, Stephan; Klein, Peter; Küfer, Karl-Heinz; Horsch, Martin; Hasse, Hans

    2014-01-01

    Molecular modelling and simulation of the surface tension of fluids with force fields is discussed. 29 real fluids are studied, including nitrogen, oxygen, carbon dioxide, carbon monoxide, fluorine, chlorine, bromine, iodine, ethane, ethylene, acetylene, propyne, propylene, propadiene, carbon disulfide, sulfur hexafluoride, and many refrigerants. The fluids are represented by two-centre Lennard-Jones plus point quadrupole models from the literature. These models were adjusted only to experimental data of the vapour pressure and saturated liquid density so that the results for the surface tension are predictions. The deviations between the predictions and experimental data for the surface tension are of the order of 20 percent. The surface tension is usually overestimated by the models. For further improvements, data on the surface tension can be included in the model development. A suitable strategy for this is multi-criteria optimization based on Pareto sets. This is demonstrated using the model for carbon d...

  4. Surface tension of polymer melts - experimental investigations of its effect on polymer-polymer adhesion

    DEFF Research Database (Denmark)

    Jankova Atanasova, Katja; Islam, Mohammad Aminul; Hansen, Hans Nørgaard

    The surface tension of polymer melts is important for the bond strength of two component polymer parts through their roles in the process of wetting, adsorption and adhesion. This investigation deals with the influence of the melt surface tension and substrate surface energy on the polymer......-polymer bond strength during two component polymer processing. Polymer materials PS, POM, ABS, PEl, PEEK and PC are chosen for the investigation. Pendant drop method showed that in case of PS and POM, the melt surface tension was decreased with increasing temperature. The substrate surface energies....... The results and discussion presented in this paper reflect the temperature dependent behaviours of the surface tension and surface energy of polymers and their effects on the polymer-polymer bond strength....

  5. Surface tension of polymer melts - experimental investigations of its effects on polymer-polymer adhesion

    DEFF Research Database (Denmark)

    Islam, Mohammad Aminul; Jankova Atanasova, Katja; Hansen, Hans Nørgaard

    The surface tension of polymer melts is important for the bond strength of two component polymer parts through their roles in the process of wetting, adsorption and adhesion. This investigation deals with the influence of the melt surface tension and substrate surface energy on the polymer......-polymer bond strength during two component polymer processing. Polymer materials PS, POM, ABS, PEI, PEEK and PC are chosen for the investigation. Pendant drop method showed that in case of PS and POM, the melt surface tension was decreased with increasing temperature. The substrate surface energies....... The results and discussion presented in this paper reflect the temperature dependent behaviours of the surface tension and surface energy of polymers and their effects on the polymer-polymer bond strength....

  6. Surface tension and related thermodynamic parameters of alcohols using the Traube stalagmometer

    Science.gov (United States)

    Dilmohamud, B. A.; Seeneevassen, J.; Rughooputh, S. D. D. V.; Ramasami, P.

    2005-11-01

    An apparatus was devised using the Traube Stalagmometer for the determination of the surface tension of the alcohols methanol, ethanol, propan-1-ol and butan-1-ol. Measurements were made under atmospheric pressure at temperatures between 288.15 K and 313.15 K. The surface tension values were correlated with temperature and surface thermodynamic parameters, namely surface entropy and surface enthalpy, were also calculated. The results obtained are in agreement with the literature and they are promising for the use of this low cost arrangement for accurate measurement of surface tension. Surface tension values were obtained with a maximum error of 0.5 mN m-1 and a maximum standard deviation of 0.8 mN m-1. We recommend this arrangement for students in advanced university courses and it can also be used for research work.

  7. Surface tension effects on vertical upward annular flows in a small diameter pipe

    Energy Technology Data Exchange (ETDEWEB)

    Sadatomi, Michio, E-mail: sadatomi@mech.kumamoto-u.ac.jp [Dept. of Advanced Mechanical Systems, Kumamoto Univ., 39-1, Kurokami 2-chome, Chuou-ku, Kumamoto 860-8555 (Japan); Kawahara, Akimaro [Dept. of Advanced Mechanical Systems, Kumamoto Univ., 39-1, Kurokami 2-chome, Chuou-ku, Kumamoto 860-8555 (Japan); Suzuki, Aruta [Plant Design & Engineering Dept., Environment, Energy & Plant Headquarters, Hitachi Zosen Corporation, 7-89, Nankokita 1-chome, Suminoe-ku, Osaka, 559-8559 (Japan)

    2016-12-15

    Highlights: • Surface tension effects were clarified on annular flow in a small diameter pipe. • The mean liquid film thickness became thinner with decreasing of surface tension. • The liquid droplet fraction and the interfacial shear stress became higher with it. • New prediction methods for the above parameters were developed and validated. - Abstract: Experiments were conducted to study the surface tension effects on vertical upward annular flows in a 5 mm I.D. pipe using water and low surface tension water with a little surfactant as the test liquid and air as the test gas. Firstly, the experimental results on the mean liquid film thickness, the liquid droplet fraction and the interfacial shear stress in annular flows together with some flow pictures are presented to clarify the surface tension effects. From these, the followings are clarified: In the low surface tension case, the liquid film surface becomes rough, the liquid film thickness thin, the liquid droplet fraction high, and the interfacial shear stress high. Secondary, correlations in literatures for the respective parameters are tested against the present data. The test results show that no correlation for the respective parameters could predict well the present data. Thus, correlations are revised by accounting for the surface tension effects. The results of the experiments, the correlations tests and their revisions mentioned above are presented in the present paper.

  8. Effect of surface tension on SiO2 -methanol nanofluids

    Science.gov (United States)

    Bhuiyan, M. H. U.; Saidur, R.; Amalina, M. A.; Mostafizur, R. M.

    2015-09-01

    Surface tension, the cohesive energy of an interface dominated the transportation behaviour of the liquids play an important role in the heat transfer performance. A new class of heat transfer fluid denoting “Nanofluids” with impressive thermo-physical properties, proved its promising potentiality in the heat transfer performance. However, very few numbers of studies observed for the effect of nanoparticles on the surface tension of liquids, also noted controversial results. In the present study, SiO2 nanoparticles dispersed in methanol solution to investigate the effect of surface tension with the change of concentration and their sizes. The most common Du-Nouy ring method was used to measure the surface tension of methanol based nanofluids by an automatic surface tensiometer.The results denote that the surface tension of the nanofluids increases with increase in concentration. On the other hand, the results indicate that the surface tension decreases with the increase in temperatures. Besides, the surface tension of SiO2-methanol nanofluids enhances compared to pure methanol. All in all, the enhancement observed 1.7% to 8.9% of the variation of volume fractions (0.05 Vol % to 0.25 Vol %) and the temperature change of 25 °C to 50 °C.

  9. Semi-implicit surface tension formulation with a Lagrangian surface mesh on an Eulerian simulation grid

    KAUST Repository

    Schroeder, Craig

    2012-02-01

    We present a method for applying semi-implicit forces on a Lagrangian mesh to an Eulerian discretization of the Navier Stokes equations in a way that produces a sparse symmetric positive definite system. The resulting method has semi-implicit and fully-coupled viscosity, pressure, and Lagrangian forces. We apply our new framework for forces on a Lagrangian mesh to the case of a surface tension force, which when treated explicitly leads to a tight time step restriction. By applying surface tension as a semi-implicit Lagrangian force, the resulting method benefits from improved stability and the ability to take larger time steps. The resulting discretization is also able to maintain parasitic currents at low levels. © 2011.

  10. An Unusual Variation of Surface Tension with Concentration of.Mixed Cationic-anionic Surfactants

    Institute of Scientific and Technical Information of China (English)

    肖进新; 暴艳霞

    2001-01-01

    There are two platforms in the surface tension vs. concentration curve (γ-lgC curve) of cationic-anionic surfactant mixtures. The first platform is the same as that of common surfactant solution, and the cross point is the CMC. After the CMC, the mixtures form precipitate. At higher concentration, the mixtures form homogeneous sloution.When the mixtures form homogeneous solution at high concentration. surface tension increases with concentration, the becomes constant.So the γ-lgC curve exhibits the second platform. The surface tension at the second platform increases by increasing molar ratio of two surfactants and polar group size of surfactants, and decreases with adding inorganic salts.

  11. The role of surface tension on the elastic decohesion of polymeric filaments

    DEFF Research Database (Denmark)

    Rasmussen, Henrik K.; Hassager, Ole

    2001-01-01

    We simulate the rapid extension of polymeric filaments between parallel plates with special attention to the role of surface tension in the symmetry breaking aximuthal instability that may occur near the end plates. The instability is viewed as a precursor to the eventual elastic decohesion...... of the filament from the plate. It is demonstrated that high Deborah numbers are needed to initiate the instability and that surface tension provides a wavenumber selection. Moreover, the surface tension has a stabilising effect on the end plate instability....

  12. A surface tension based method for measuring oil dispersant concentration in seawater.

    Science.gov (United States)

    Cai, Zhengqing; Gong, Yanyan; Liu, Wen; Fu, Jie; O'Reilly, S E; Hao, Xiaodi; Zhao, Dongye

    2016-08-15

    This work developed a new method to determine concentration of Corexit EC9500A, and likely other oil dispersants, in seawater. Based on the principle that oil dispersants decrease surface tension, a linear correlation was established between the dispersant concentration and surface tension. Thus, the dispersant concentration can be determined by measuring surface tension. The method can accurately analyze Corexit EC9500A in the concentration range of 0.5-23.5mg/L. Minor changes in solution salinity (oil dispersants in water/seawater, which has been desired by the oil spill research community and industries.

  13. Hydrophobicity, surface tension, and zeta potential measurements of glass-reinforced hydroxyapatite composites.

    Science.gov (United States)

    Lopes, M A; Monteiro, F J; Santos, J D; Serro, A P; Saramago, B

    1999-06-15

    Wettability and zeta potential studies were performed to characterize the hydrophobicity, surface tension, and surface charge of P2O5-glass-reinforced hydroxyapatite composites. Quantitative phase analysis was performed by the Rietveld method using GSAS software applied to X-ray diffractograms. Surface charge was assessed by zeta potential measurements. Protein adsorption studies were performed using vitronectin. Contact angles and surface tensions variation with time were determined by the sessile and pendent drop techniques, respectively, using ADSA-P software. The highest (-18.1 mV) and lowest (-28.7 mV) values of zeta potential were found for hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP), respectively, with composite materials presenting values in between. All studied bioceramic materials showed similar solid surface tension. For HA and beta-TCP, solid surface tensions of 46.7 and 45.3 mJ/m2, respectively, were obtained, while composites presented intermediate surface tension values. The dispersive component of surface tension was the predominant one for all materials studied. Adhesion work values between the vitronectin solution and HA and beta-TCP were found to be 79.8 and 88.0 mJ/m2, respectively, while the 4.0 wt % glass composites showed slightly lower values than the 2.5 wt % ones. The presence of beta-TCP influenced surface charge, hydrophobicity, and protein adsorption of the glass-reinforced HA composites, and therefore indirectly affected cell-biomaterial interactions.

  14. [Determination of critical surface tension--a comparison of 2 methods].

    Science.gov (United States)

    Lippold, B C; Ohm, A

    1988-03-01

    Two methods for the determination of the critical surface tension (gamma c) of pharmaceutical powders are compared: the so called "sinking-technique", which works by measuring the complete sinking of powders in liquids of varying surface tension and the determination of the critical surface tension by measuring the contact angle in dependence on the surface tension of wetting solvent/water-mixtures by means of the sessile drop-technique. The simple sinking-technique gives gamma c-values which only show a moderate degree of agreement with those determined by the sessile drop-technique. Thus the values determined by the sinking-technique are usually 1-3 mN/m higher than those determined by the sessile drop-technique.

  15. Interfacial tension and surface pressure of high density lipoprotein, low density lipoprotein, and related lipid droplets

    National Research Council Canada - National Science Library

    Ollila, O H Samuli; Lamberg, Antti; Lehtivaara, Maria; Koivuniemi, Artturi; Vattulainen, Ilpo

    2012-01-01

    .... Interfacial tension and surface pressure of these particles are of great interest because they are related to the shape and the stability of the droplets and to protein adsorption at the interface...

  16. A Surface Tension Model for Liquid Mixtures Based on NRTL Equation

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A new equation for predicting surface tension is proposed based on the thermodynamic definition of surface tension and the expression of the Gibbs free energy of the system. Using the NRTL equation to represent the excess Gibbs free energy, a two-parameter surface tension equation is derived. The feasibility of the new equation has been tested in terms of 124 binary and 16 multicomponent systems(13-ternary and 3-quaternary) with absolute relative deviations of 0.59% and 1.55% respectively. This model is also predictive for the temperature dependence of surface tension of liquid mixtures. It is shown that, with good accuracy, this equation is simple and reliable for practical use.

  17. Molecular dynamics simulations of the surface tension of oxygen-supersaturated water

    Directory of Open Access Journals (Sweden)

    S. Jain

    2017-04-01

    Full Text Available In this work, non-reactive molecular dynamic simulations were conducted to determine the surface tension of water as a function of the concentration of the dissolved gaseous molecules (O2, which would in turn help to predict the pressure inside the nanobubbles under supersaturation conditions. Knowing the bubble pressure is a prerequisite for understanding the mechanisms behind the spontaneous combustion of the H2/O2 gases inside the nanobubbles. First, the surface tension of pure water was determined using the planar interface method and the Irving and Kirkwood formula. Next, the surface tension of water containing four different supersaturation concentrations (S of O2 gas molecules was computed considering the curved interface of a nanobubble. The surface tension of water was found to decrease with an increase in the supersaturation ratio or the concentration of the dissolved O2 gas molecules.

  18. Computing masses and surface tension from effective transfer matrices

    CERN Document Server

    Hasenbusch, M; Pinn, K

    1994-01-01

    We propose an effective transfer-matrix method that allows a measurement of tunnelling correlation lengths that are orders of magnitude larger than the lattice extension. Combining this method with a particularly efficient implementation of the multimagnetical algorithm we were able to determine the interface tension of the 3D Ising model close to criticality with a relative error of less than 1 per cent.

  19. Critical-point analysis of the liquid-vapor interfacial surface tension

    Science.gov (United States)

    Salvino, R. E.

    1990-01-01

    The interfacial surface tension of the liquid-vapor system is analyzed near the critical point in a manner similar to bulk thermodynamic critical-point analyses. This is accomplished by a critical-point analysis of the single-phase hard-wall surface tension. Both a Landau expansion and a scaling theory equation of state are investigated. Some general exponent relations are derived and, in addition, some thermodynamically defined correlation lengths are discussed.

  20. Surface tension phenomena in the xylem sap of three diffuse porous temperate tree species.

    Science.gov (United States)

    Christensen-Dalsgaard, Karen K; Tyree, Melvin T; Mussone, Paolo G

    2011-04-01

    In plant physiology models involving bubble nucleation, expansion or elimination, it is typically assumed that the surface tension of xylem sap is equal to that of pure water, though this has never been tested. In this study we collected xylem sap from branches of the tree species Populus tremuloides, Betula papyrifera and Sorbus aucuparia over 3 months. We measured the instantaneous surface tension and followed changes over a period of 0.5-5 h using the pendant drop technique. In all three species the instantaneous surface tension was equal to or within a few percent of that of pure water. Further, in B. papyrifera and S. aucuparia the change over time following drop establishment, although significant, was very small. In P. tremuloides, however, there was a steep decline in surface tension over time that leveled off towards values 21-27% lower than that of pure water. This indicated the presence of surfactants. The values were lower for thinner distal branch segments than for proximal ones closer to the trunk. In some species it appears valid to assume that the surface tension of xylem sap is equal to that of water. However, in branch segments of P. tremuloides close to the terminal bud and hence potentially in other species as well, it may be necessary to take into account the presence of surfactants that reduce the surface tension over time.

  1. Surface tension of nitric oxide and its binary mixtures with krypton, methane, and ethene

    Energy Technology Data Exchange (ETDEWEB)

    Calado, J.C.G.; Santos Mendonca, A.F.S. dos; Saramago, B.J.V.; Soares, V.A.M. [Instituto Superior Tecnico, Lisbon (Portugal). Centro de Quimica Estrutural

    1997-05-15

    The surface tension of three binary liquid mixtures of NO with Kr, CH{sub 4}, and C{sub 2}H{sub 4} has been determined as a function of composition in the temperature range 102.0 to 119.0 K. These measurements are a contribution to the study of binary liquid mixtures in which one component is unassociated while the molecules of the other can associate between themselves. Nitric oxide is the simplest molecule capable of forming dimers, but not larger aggregates. This results in the surface tension of liquid nitric oxide having a strong temperature dependence: when the temperature increases the degree of dimerization decreases, contributing to a larger decrease of the surface tension. The surface tension of NO mixtures shows strong deviations from ideality. The mixtures containing Kr and CH{sub 4} exhibit negative deviations, while for the NO + C{sub 2}H{sub 4} system the surface tension shows a complex dependence on the composition. This strong departure from ideality had already been found for the bulk properties of these three systems. The surface tension of the CH{sub 4} + Kr system, already well characterized in the literature, was also measured to test the equipment.

  2. Effects of internal pressure and surface tension on the growth-induced wrinkling of mucosae.

    Science.gov (United States)

    Xie, Wei-Hua; Li, Bo; Cao, Yan-Ping; Feng, Xi-Qiao

    2014-01-01

    Surface wrinkling of mucosae is crucial for the biological functions of many living tissues. In this paper, we investigate the instability of a cylindrical tube consisting of a mucosal layer and a submucosal layer. Our attention is focused on the effects of internal pressure and surface tension on the critical condition and mode number of surface wrinkling induced by tissue growth. It is found that the internal pressure plays a stabilizing role but basically has no effect on the critical mode number. Surface tension also stabilizes the system and reduces the critical mode number of surface patterns. Besides, the thinner the mucosal layer, the more significant the effect of surface tension. This work may help gain insights into the surface wrinkling and morphological evolution of such tubular organs as airways and esophagi. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Surface Tension, Surface Stiffness, and Surface Width of the 3-dimensional Ising Model on a Cubic Lattice

    CERN Document Server

    Hasenbusch, M.; Hasenbusch, Martin; Pinn, Klaus

    1992-01-01

    We compute properties of the interface of the 3-dimensional Ising model for a wide range of temperatures and for interface extensions up to 64 by 64. The interface tension sigma is obtained by integrating the surface energy density over the inverse temperature beta. The surface stiffness coefficient kappa is determined. We also study universal quantities like xi^2 sigma and xi^2 kappa. The behavior of the interfacial width on lattices up to 512 times 512 times 27 is also investigated.

  4. Computer modelling of the surface tension of the gas-liquid and liquid-liquid interface.

    Science.gov (United States)

    Ghoufi, Aziz; Malfreyt, Patrice; Tildesley, Dominic J

    2016-03-07

    This review presents the state of the art in molecular simulations of interfacial systems and of the calculation of the surface tension from the underlying intermolecular potential. We provide a short account of different methodological factors (size-effects, truncation procedures, long-range corrections and potential models) that can affect the results of the simulations. Accurate calculations are presented for the calculation of the surface tension as a function of the temperature, pressure and composition by considering the planar gas-liquid interface of a range of molecular fluids. In particular, we consider the challenging problems of reproducing the interfacial tension of salt solutions as a function of the salt molality; the simulations of spherical interfaces including the calculation of the sign and size of the Tolman length for a spherical droplet; the use of coarse-grained models in the calculation of the interfacial tension of liquid-liquid surfaces and the mesoscopic simulations of oil-water-surfactant interfacial systems.

  5. Quantification of surface tension and internal pressure generated by single mitotic cells.

    Science.gov (United States)

    Fischer-Friedrich, Elisabeth; Hyman, Anthony A; Jülicher, Frank; Müller, Daniel J; Helenius, Jonne

    2014-08-29

    During mitosis, adherent cells round up, by increasing the tension of the contractile actomyosin cortex while increasing the internal hydrostatic pressure. In the simple scenario of a liquid cell interior, the surface tension is related to the local curvature and the hydrostatic pressure difference by Laplace's law. However, verification of this scenario for cells requires accurate measurements of cell shape. Here, we use wedged micro-cantilevers to uniaxially confine single cells and determine confinement forces while concurrently determining cell shape using confocal microscopy. We fit experimentally measured confined cell shapes to shapes obeying Laplace's law with uniform surface tension and find quantitative agreement. Geometrical parameters derived from fitting the cell shape, and the measured force were used to calculate hydrostatic pressure excess and surface tension of cells. We find that HeLa cells increase their internal hydrostatic pressure excess and surface tension from ≈ 40 Pa and 0.2 mNm(-1) during interphase to ≈ 400 Pa and 1.6 mNm(-1) during metaphase. The method introduced provides a means to determine internal pressure excess and surface tension of rounded cells accurately and with minimal cellular perturbation, and should be applicable to characterize the mechanical properties of various cellular systems.

  6. Prediction of surface and interfacial tension based on thermodynamic data and CALPHAD approach

    Institute of Scientific and Technical Information of China (English)

    QIAO Zhiyu; CAO Zhanmin; Tanaka Toshihiro

    2006-01-01

    In this article, following a brief introduction concerning experimental measurements of surface and interfacial tensions, methods for calculating surface tension and surface segregation for binary, ternary, and multicomponent high-temperature melts based on Bulter's original treatment [1 ] and on available physical properties and thermodynamic data, especially excess Gibbs free energies of bulk phase and surface phase versus temperature obtained from thermodynamic databases using the calculation of phase diagram (CALPHAD) approach, with special attention to the model parameter β, have been described. In addition, the geometric models can be extended to predict surface tensions of multicom ponent systems from those of sub-binary systems. For illustration, some calculated examples, including Pb-free soldering systems and phase-diagram evaluation of binary alloys in nanoparticle systems are given. On the basis of surface tensions of high-temperature melts, interfacial tensions between liquid alloy and molten slag as well as molten slag and molten matter can be calculated using the Girifalco-Good equation [2]. Modifications are suggested in the Nishizawa's model [3] for estimation of interfacial tension in liquid metal (A)/ceramics (MX) systems so that the calculations can be carried out based on the sublattice model and thermodynamic data, without deliberately differentiating the phase of MX at high temperature. Finally, the derivation of an approximate expression for predicting interfacial tension between the high-temperature multicomponent melts, employing Becket's model [4] in conjunction with Bulter's equation and interfacial tension data of the simple systems is described, and some examples concerning pyrometallurgical systems are given for better understanding.

  7. Surface Tension of Acid Solutions: Fluctuations beyond the Non-linear Poisson-Boltzmann Theory

    CERN Document Server

    Markovich, Tomer; Podgornik, Rudi

    2016-01-01

    We extend our previous study of surface tension of ionic solutions and apply it to the case of acids (and salts) with strong ion-surface interactions. These ion-surface interactions yield a non-linear boundary condition with an effective surface charge due to adsorption of ions from the bulk onto the interface. The calculation is done using the loop-expansion technique, where the zero-loop (mean field) corresponds of the non-linear Poisson-Boltzmann equation. The surface tension is obtained analytically to one-loop order, where the mean-field contribution is a modification of the Poisson-Boltzmann surface tension, and the one-loop contribution gives a generalization of the Onsager-Samaras result. Our theory fits well a wide range of different acids and salts, and is in accord with the reverse Hofmeister series for acids.

  8. Dynamic surface tension of heat transfer additives suitable for use in steam condensers and absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Jun, Yong-Du [Department of Mechanical and Automotive Engineering, Kongju National University, Kongju, Chungnam, 314-701 (Korea); Kim, Kwang J.; Kennedy, John M. [Department of Mechanical Engineering, University of Nevada-Reno, MS 312, Reno, NV 89557 (United States)

    2010-03-15

    Additives are often effectively used in enhancing heat transfer by creating a surface tension gradient on the surface of a condensate film to induce Marangoni driven ''dropwise-like'' condensation. The objective of the current study is to use the Maximum Bubble Pressure Method (MBPM) to evaluate dynamic behavior of the surface tension of solutions of three different additives (2-ethoxy ethanol, isobutylamine, and 2-ethyl-1-hexanol) of varying concentrations with water. It was shown that the effects of 2-ethoxy ethanol on surface tension was primarily dependent on solute concentration and showed little dependence on time (i.e. surface age of bubble). While both isobutylamine and 2-ethyl-1-hexanol showed strong dependence on both concentration and time, the effects of the later were far more dramatic. The results for all solutions are presented as functions of concentration and time (i.e. surface age of bubble). (author)

  9. A novel optimal sensitivity design scheme for yarn tension sensor using surface acoustic wave device.

    Science.gov (United States)

    Lei, Bingbing; Lu, Wenke; Zhu, Changchun; Liu, Qinghong; Zhang, Haoxin

    2014-08-01

    In this paper, we propose a novel optimal sensitivity design scheme for the yarn tension sensor using surface acoustic wave (SAW) device. In order to obtain the best sensitivity, the regression model between the size of the SAW yarn tension sensor substrate and the sensitivity of the SAW yarn tension sensor was established using the least square method. The model was validated too. Through analyzing the correspondence between the regression function monotonicity and its partial derivative sign, the effect of the SAW yarn tension sensor substrate size on the sensitivity of the SAW yarn tension sensor was investigated. Based on the regression model, a linear programming model was established to gain the optimal sensitivity of the SAW yarn tension sensor. The linear programming result shows that the maximum sensitivity will be achieved when the SAW yarn tension sensor substrate length is equal to 15 mm and its width is equal to 3mm within a fixed interval of the substrate size. An experiment of SAW yarn tension sensor about 15 mm long and 3mm wide was presented. Experimental results show that the maximum sensitivity 1982.39 Hz/g was accomplished, which confirms that the optimal sensitivity design scheme is useful and effective. Copyright © 2014. Published by Elsevier B.V.

  10. Surface Tension of Acid Solutions: Fluctuations beyond the Nonlinear Poisson-Boltzmann Theory.

    Science.gov (United States)

    Markovich, Tomer; Andelman, David; Podgornik, Rudi

    2017-01-10

    We extend our previous study of surface tension of ionic solutions and apply it to acids (and salts) with strong ion-surface interactions, as described by a single adhesivity parameter for the ionic species interacting with the interface. We derive the appropriate nonlinear boundary condition with an effective surface charge due to the adsorption of ions from the bulk onto the interface. The calculation is done using the loop-expansion technique, where the zero loop (mean field) corresponds of the full nonlinear Poisson-Boltzmann equation. The surface tension is obtained analytically to one-loop order, where the mean-field contribution is a modification of the Poisson-Boltzmann surface tension and the one-loop contribution gives a generalization of the Onsager-Samaras result. Adhesivity significantly affects both contributions to the surface tension, as can be seen from the dependence of surface tension on salt concentration for strongly absorbing ions. Comparison with available experimental data on a wide range of different acids and salts allows the fitting of the adhesivity parameter. In addition, it identifies the regime(s) where the hypotheses on which the theory is based are outside their range of validity.

  11. Surface tension method for determining binding constants for cyclodextrin inclusion complexes of ionic surfactants

    Energy Technology Data Exchange (ETDEWEB)

    Dharmawardana, U.R.; Christian, S.D.; Tucker, E.E.; Taylor, R.W.; Scamehorn, J.F. (Univ. of Oklahoma, Norman, OK (United States))

    1993-09-01

    A new method has been developed for determining binding constants of complexes of cyclodextrins with surface-active compounds, including water-soluble ionic surfactants. The technique requires measuring the change in surface tension caused by addition of a cyclodextrin (CD) to aqueous solutions of the surfactant; the experimental results lead directly to inferred values of the thermodynamic activity of the surfactant. Surface tension results are reported for three different surfactants sodium dodecyl sulfate (SDS), cetylpyridinium chloride (CPC), and cetyltrimethylammonium bromide (CTAB) in the presence and in the absence of added [beta]-CD. Data for CPC have been obtained at surfactant concentrations below and above the critical micelle concentration. Correlations between surface tension and surfactant activity are expressed by the Szyszkowski equation, which subsumes the Langmuir adsorption model and the Gibbs equation. It is observed that the surface tension increases monotonically as [beta]-cyclodextrin is added to ionic surfactant solutions. At concentrations of CD well in excess of the surfactant concentration, the surface tension approaches that of pure water, indicating that neither the surfactant-CD complexes nor CD itself are surface active. Binding constants are inferred from a model that incorporates the parameters of the Szyszkowski equation and mass action constants relating to the formation of micelles from monomers of the surfactant and the counterion. Evidence is given that two molecules of CD can complex the C-16 hydrocarbon chain of the cetyl surfactants. 30 refs., 5 figs., 1 tab.

  12. Experimental evaluation of apparent tissue surface tension based on the exact solution of the Laplace equation

    Science.gov (United States)

    Norotte, C.; Marga, F.; Neagu, A.; Kosztin, I.; Forgacs, G.

    2008-02-01

    The notion of apparent tissue surface tension offered a systematic way to interpret certain morphogenetic processes in early development. It also allowed deducing quantitative information on cellular and molecular parameters that is otherwise difficult to obtain. To accurately determine such tensions we combined novel experiments with the exact solution of the Laplace equation for the profile of a liquid drop under the employed experimental conditions and used the exact solution to evaluate data collected on tissues. Our results confirm that tissues composed of adhesive and motile cells indeed can be characterized in terms of well-defined apparent surface tension. Our experimental technique presents a way to measure liquid interfacial tensions under conditions when known methods fail.

  13. On the measurement of surface tension in binders used for moulding sands

    Directory of Open Access Journals (Sweden)

    B. Hutera

    2008-07-01

    Full Text Available The surface tension of foundry binders is a very important parameter affecting the properties of a sand-binder system. Combined with other parameters, its value determines an outcome of the process of moulding sand preparation and the mechanical properties of the ready moulding composition. The problem of how to measure the surface tension of binders used in preparation of moulding sands is discussed only occasionally. Indirectly, the surface tension is characterised by the value of a contact angle, but it never means that these two parameters can be considered identical. Numerous methods are available and used at present to measure the surface tension, among others, the capillary rise method, the spinning drop method, the sessile drop method, the pendant drop method, the method of pulled out ring (or plate, or frame. There is also a rich variety of devices offered with different measuring methods. The devices are modern and represent a high level of the technical skill and art. Unfortunately, also their price is high. It is, however, possible to obtain the reliable results of the surface tension measurement using relatively simple methods, viz. the stalagmometric method and the capillary rise method. What is necessary are proper conditions of the measurement, directly related with the specific properties of binders. The present paper gives examples of the results obtained during measurement of the surface tension of some selected binders. Attention was drawn to the methods of taking measurements, and the obtained results were discussed and analysed. The possibilities of detemining the surface tension of the examined binders from the results of the contact angle measurements using the “sessile drop” and “pendant drop” methods were outlined.

  14. Effect of Dynamic Surface Tension on Droplet Formation of Surfactant Solution Injected from a Capillary Tube

    OpenAIRE

    山本, 剛宏; 加藤, 有樹; 山下, 敦史; Takehiro, YAMAMOTO; Yuki, Kato; Atsushi, Yamashita; 阪大院工; Osaka University

    2008-01-01

    Effects of dynamic surface tension on the droplet formation of surfactant solutions were studied. Aqueous solutions of CTAB at several surfactant concentrations were used as test fluids. A droplet formed when a surfactant solution was injected from a capillary tube was investigated and the relation between the droplet diameter and the injection velocity was measured. The diameter increased with increasing the velocity at relatively low velocities because the dynamic tension also increased. Ho...

  15. Surface Tensions of Ionic Liquids: Non-Regular Trend Along the Number of Cyano Groups

    Science.gov (United States)

    Almeida, Hugo F. D.; Carvalho, Pedro J.; Kurnia, Kiki A.; Lopes-da-Silva, José A.; Coutinho, João A. P.; Freire, Mara G.

    2016-01-01

    Ionic liquids (ILs) with cyano-functionalized anions are a set of fluids that are still poorly characterized despite their remarkably low viscosities and potential applications. Aiming at providing a comprehensive study on the influence of the number of –CN groups through the surface tension and surface organization of ILs, the surface tensions of imidazolium-based ILs with cyano-functionalized anions were determined at atmospheric pressure and in the (298.15 to 343.15) K temperature range. The ILs investigated are based on 1-alkyl-3-methylimidazolium cations (alkyl = ethyl, butyl and hexyl) combined with the [SCN]-, [N(CN)2]−, [C(CN)3]− and [B(CN)4]-anions. Although the well-known trend regarding the surface tension decrease with the increase of the size of the aliphatic moiety at the cation was observed, the order obtained for the anions is more intricate. For a common cation and at a given temperature, the surface tension decreases according to: [N(CN)2]- > [SCN]- > [C(CN)3]- > [B(CN)4]-. Therefore, the surface tension of this homologous series does not decrease with the increase of the number of –CN groups at the anion as has been previously shown by studies performed with a more limited matrix of ILs. A maximum in the surface tension and critical temperature was observed for [N(CN)2]-based ILs. Furthermore, a minimum in the surface entropy, indicative of a highly structured surface, was found for the same class of ILs. All these evidences seem to be a result of stronger hydrogen-bonding interactions occurring in [N(CN)2]-based ILs, when compared with the remaining CN-based counterparts, and as sustained by cation-anion interaction energies derived from the Conductor Like Screening Model for Real Solvents (COSMO-RS). PMID:27642224

  16. Surface tension of water and acid gases from Monte Carlo simulations.

    Science.gov (United States)

    Ghoufi, A; Goujon, F; Lachet, V; Malfreyt, P

    2008-04-21

    We report direct Monte Carlo (MC) simulations on the liquid-vapor interfaces of pure water, carbon dioxide, and hydrogen sulfide. In the case of water, the recent TIP4P/2005 potential model used with the MC method is shown to reproduce the experimental surface tension and to accurately describe the coexistence curves. The agreement with experiments is also excellent for CO(2) and H(2)S with standard nonpolarizable models. The surface tensions are calculated by using the mechanical and the thermodynamic definitions via profiles along the direction normal to the surface. We also discuss the different contributions to the surface tension due to the repulsion-dispersion and electrostatic interactions. The different profiles of these contributions are proposed in the case of water.

  17. Surface tension of expanded slag from steel manufacturing in electrical furnace

    Directory of Open Access Journals (Sweden)

    J. Łabaj

    2011-07-01

    Full Text Available In the article a research on the surface tension of slag was conducted from the process of obtaining steel in the electric furnace. Melting in the graphite melting crucible caused the slag to foam. The measurement of the surface tension is being conducted with method of rejection. They make the measurement of maximum power needed for the liquid to reject the working element of the apparatus from the surface. The research was conducted in the temperature of 1 673 – 1 723 K. The results of the measurements allowed to determine the surface tension of slag, which in the analysed scope of the temperature is being changed from 454 to 345 mN•m-1.

  18. Dropwise Condensation of Low Surface Tension Fluids on iCVD Grafted Polymer Films

    Science.gov (United States)

    Khalil, Karim; Gleason, Karen; Varanasi, Kripa

    2016-11-01

    A large majority of the work devoted to surface engineering for promoting dropwise condensation heat transfer has focused on steam. Much less attention has been dedicated to the condensation of low surface tension fluids such as hydrocarbons, cryogens, and fluorinated refrigerants, which are used in several industrial applications, including LNG storage and organic Rankine cycles used for heat recovery from low temperature sources such as biomass combustion, industrial waste, or geothermal heat sources. Most hydrophobic modifiers used previously to promote dropwise condensation are silane-based monolayers that have been shown to rapidly degrade under industrial conditions. Here we investigate condensation behavior of a variety of low surface tension liquids on durable covalently-grafted polymer films deposited using initiated chemical vapor deposition (iCVD) on metals such as titanium. We observe a four to seven-fold improvement in the vapor-side heat transfer coefficient by promoting dropwise condensation of low surface tension fluids on these stable films.

  19. Ternary Free Energy Lattice Boltzmann Model with Tunable Surface Tensions and Contact Angles

    CERN Document Server

    Semprebon, Ciro; Kusumaatmaja, Halim

    2015-01-01

    We present a new ternary free energy lattice Boltzmann model. The distinguishing feature of our model is that we are able to analytically derive and independently vary all fluid-fluid surface tensions and the solid surface contact angles. We carry out a number of benchmark tests: (i) double emulsions and liquid lenses to validate the surface tensions, (ii) ternary fluids in contact with a square well to compare the contact angles against analytical predictions, and (iii) ternary phase separation to verify that the multicomponent fluid dynamics is accurately captured. Additionally we also describe how the model here presented here can be extended to include an arbitrary number of fluid components.

  20. Effect of concentration and temperature on surface tension of sodium hyaluronate saline solutions.

    Science.gov (United States)

    Ribeiro, Walkiria; Mata, José Luis; Saramago, Benilde

    2007-06-19

    The effect of concentration and temperature on the surface tension of sodium hyaluronate (NaHA) saline solutions was investigated using the technique of the shape of pendant drops. The decay rate of the surface tension with the increase of NaHA concentration was well-described by the empirical Hua-Rosen equation. Adsorption at the air-liquid interface was estimated using the Gibbs equation. The temperature dependence of a dilute solution and a semidilute entangled solution was numerically fitted with a second-order polynomial equation. The surface behavior of the NaHA saline solutions was interpreted in terms of their known viscoelastic properties.

  1. 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.

  2. Modeling the surface tension of complex, reactive organic-inorganic mixtures

    Science.gov (United States)

    Schwier, A. N.; Viglione, G. A.; Li, Z.; McNeill, V. Faye

    2013-11-01

    Atmospheric aerosols can contain thousands of organic compounds which impact aerosol surface tension, affecting aerosol properties such as heterogeneous reactivity, ice nucleation, and cloud droplet formation. We present new experimental data for the surface tension of complex, reactive organic-inorganic aqueous mixtures mimicking tropospheric aerosols. Each solution contained 2-6 organic compounds, including methylglyoxal, glyoxal, formaldehyde, acetaldehyde, oxalic acid, succinic acid, leucine, alanine, glycine, and serine, with and without ammonium sulfate. We test two semi-empirical surface tension models and find that most reactive, complex, aqueous organic mixtures which do not contain salt are well described by a weighted Szyszkowski-Langmuir (S-L) model which was first presented by Henning et al. (2005). Two approaches for modeling the effects of salt were tested: (1) the Tuckermann approach (an extension of the Henning model with an additional explicit salt term), and (2) a new implicit method proposed here which employs experimental surface tension data obtained for each organic species in the presence of salt used with the Henning model. We recommend the use of method (2) for surface tension modeling of aerosol systems because the Henning model (using data obtained from organic-inorganic systems) and Tuckermann approach provide similar modeling results and goodness-of-fit (χ2) values, yet the Henning model is a simpler and more physical approach to modeling the effects of salt, requiring less empirically determined parameters.

  3. Modeling the surface tension of complex, reactive organic-inorganic mixtures

    Directory of Open Access Journals (Sweden)

    A. N. Schwier

    2013-01-01

    Full Text Available Atmospheric aerosols can contain thousands of organic compounds which impact aerosol surface tension, affecting aerosol properties such as cloud condensation nuclei (CCN ability. We present new experimental data for the surface tension of complex, reactive organic-inorganic aqueous mixtures mimicking tropospheric aerosols. Each solution contained 2–6 organic compounds, including methylglyoxal, glyoxal, formaldehyde, acetaldehyde, oxalic acid, succinic acid, leucine, alanine, glycine, and serine, with and without ammonium sulfate. We test two surface tension models and find that most reactive, complex, aqueous organic mixtures which do not contain salt are well-described by a weighted Szyszkowski–Langmuir (S–L model which was first presented by Henning et al. (2005. Two approaches for modeling the effects of salt were tested: (1 the Tuckermann approach (an extension of the Henning model with an additional explicit salt term, and (2 a new implicit method proposed here which employs experimental surface tension data obtained for each organic species in the presence of salt used with the Henning model. We recommend the use of method (2 for surface tension modeling because the Henning model (using data obtained from organic-inorganic systems and Tuckermann approach provide similar modeling fits and goodness of fit (χ2 values, yet the Henning model is a simpler and more physical approach to modeling the effects of salt, requiring less empirically determined parameters.

  4. Line tension and its influence on droplets and particles at surfaces

    Science.gov (United States)

    Law, Bruce M.; McBride, Sean P.; Wang, Jiang Yong; Wi, Haeng Sub; Paneru, Govind; Betelu, Santigo; Ushijima, Baku; Takata, Youichi; Flanders, Bret; Bresme, Fernando; Matsubara, Hiroki; Takiue, Takanori; Aratono, Makoto

    2017-02-01

    In this review we examine the influence of the line tension τ on droplets and particles at surfaces. The line tension influences the nucleation behavior and contact angle of liquid droplets at both liquid and solid surfaces and alters the attachment energetics of solid particles to liquid surfaces. Many factors, occurring over a wide range of length scales, contribute to the line tension. On atomic scales, atomic rearrangements and reorientations of submolecular components give rise to an atomic line tension contribution τatom (∼1 nN), which depends on the similarity/dissimilarity of the droplet/particle surface composition compared with the surface upon which it resides. At nanometer length scales, an integration over the van der Waals interfacial potential gives rise to a mesoscale contribution |τvdW| ∼ 1-100 pN while, at millimeter length scales, the gravitational potential provides a gravitational contribution τgrav ∼ +1-10 μN. τgrav is always positive, whereas, τvdW can have either sign. Near wetting, for very small contact angle droplets, a negative line tension may give rise to a contact line instability. We examine these and other issues in this review.

  5. Surface-tension phenomena in organismal biology: an introduction to the symposium.

    Science.gov (United States)

    Bourouiba, Lydia; Hu, David L; Levy, Rachel

    2014-12-01

    Flows driven by surface tension are both ubiquitous and diverse, involving the drinking of birds and bees, the flow of xylem in plants, the impact of raindrops on animals, respiration in humans, and the transmission of diseases in plants and animals, including humans. The fundamental physical principles underlying such flows provide a unifying framework to interpret the adaptations of the microorganisms, animals, and plants that rely upon them. The symposium on "Surface-Tension Phenomena in Organismal Biology" assembled an interdisciplinary group of researchers to address a large spectrum of topics, all articulated around the role of surface tension in shaping biology, health, and ecology. The contributions to the symposium and the papers in this issue are meant to be a starting point for novices to familiarize themselves with the fundamentals of flows driven by surface tension; to understand how they can play a governing role in many settings in organismal biology; and how such understanding of nature's use of surface tension can, in turn, inspire humans to innovate.

  6. Achieving tunable surface tension in the pseudopotential lattice Boltzmann modeling of interface dynamics

    CERN Document Server

    Li, Q

    2013-01-01

    In this paper, we aim to address an important issue about the pseudopotential lattice Boltzmann (LB) model, which has attracted much attention as a mesoscopic model for simulating interfacial dynamics of complex fluids, but suffers from the problem that the surface tension cannot be tuned independently of the density ratio. In the literature, a multi-range potential was devised to adjust the surface tension [Sbragaglia et al., Phys. Rev. E, 2007, 75, 026702; Sbragaglia et al. Soft Matter, 2012, 8, 10773]. However, this approach was found to be unable to keep the density ratio unchanged when the surface tension is adjusted. An alternative approach is therefore proposed in the present work. The basic strategy is to add a new source term to the LB equation so as to tune the surface tension of the pseudopotential LB model. The proposed approach can guarantee that the adjustment of the surface tension does not affect the mechanical stability condition of the pseudopotential LB model, and thus provides a separate c...

  7. Modeling phase distribution of water-soluble organics in aqueous solutions using surface tension data

    Science.gov (United States)

    Cline, B.; Hiatt, J.; Aumann, E.; Cabrera, J.; Tabazadeh, A.

    2006-12-01

    A good fraction (greater than 30 percent) of submicron particle mass in the atmosphere is often composed of water-soluble organic carbon. Identifiable, water-miscible organics, such as, known sugars, small alcohols, small diacids, etc. comprise only a small fraction of the water-soluble mass (about 1-2 percent). Most of the water-soluble mass is often composed of unidentifiable, humic-like materials, which are commonly refereed to as HULIS. Humic substances are known to form colloids in aqueous solutions at very low aqueous concentrations. Thus, it is likely for HULIS to also be colloid-forming in aqueous solutions. Here, we present surface tension measurements of water-miscible and colloid-forming organics, using methanol and sodium laurate as analogs, respectively. By relating the change in surface tension to chemical potential of the solution, we determine a relationship between surface tension and the surface excess of solute; that is, the number of molecules of solute adsorbed at the surface. Assuming surface acts as a monolayer, we model the adsorption with a Langmuir isotherm to extract the surface excess as a function of solute mole fraction. This relationship allows us to calculate the solute's distribution between bulk and surface phases for methanol, and in bulk, surface and colloid phases for sodium laurate. A colloid of sodium laurate contains approximately 100 laurate anions in a spherical cluster. We present adsorption constants for methanol and sodium laurate (derived from our surface tension data), critical micelle concentration for sodium laurate (derived from our surface tension data), and all the other thermocehmical constants (obtained from the literature) required to constrain a model for determining phase partitioning of organics in aqueous solutions.

  8. Ternary solution of sodium chloride, succinic acid and water; surface tension and its influence on cloud droplet activation

    Directory of Open Access Journals (Sweden)

    J. Vanhanen

    2008-08-01

    Full Text Available Surface tension of ternary solution of sodium chloride, succinic acid and water was measured as a function of both composition and temperature by using the capillary rise technique. Both sodium chloride and succinic acid are found in atmospheric aerosols, the former being main constituent of marine aerosol. Succinic acid was found to decrease the surface tension of water already at very low concentrations. Sodium chloride increased the surface tension linearly as a function of the concentration. Surface tensions of both binary solutions agreed well with the previous measurements. Succinic acid was found to lower the surface tension even if sodium chloride is present, indicating that succinic acid, as a surface active compound, tends to concentrate to the surface. An equation based on thermodynamical relations was fitted to the data and extrapolated to the whole concentration range by using estimated surface tensions for pure compounds. As a result, we obtained an estimate of surface tensions beyond solubility limits in addition to a fit to the experimental data. The parameterization can safely be used at temperatures from 10 to 30°C. These kinds of parameterizations are important for example in atmospheric nucleation models. To investigate the influence of surface tension on cloud droplet activation, the surface tension parameterization was included in an adiabatic air parcel model. Usually in cloud models the surface tension of pure water is used. Simulations were done for characteristic marine aerosol size distributions consisting of the considered ternary mixture. We found that by using the surface tension of pure water, the amount of activated particles is underestimated up to 8% if particles contain succinic acid and overestimated it up to 8% if particles contain only sodium chloride. The surface tension effect was found to increase with increasing updraft velocity.

  9. Surface tension in the cold and dense chiral transition and astrophysical applications

    CERN Document Server

    Palhares, L F

    2011-01-01

    The surface tension of cold and dense QCD phase transitions has appeared recently as a key ingredient in different astrophysical scenarios, ranging from core-colapse supernovae explosions to compact star structure. If the surface tension is low enough, observable consequences are possible. Its value is however not known from first-principle methods in QCD, calling for effective approaches. Working within the framework of homogeneous nucleation by Langer, we discuss the steps that are needed to obtain the nucleation parameters from a given effective potential. As a model for deriving the effective potential for the chiral transition, we adopt the linear sigma model with constituent quarks at very low temperatures, which provides an effective description for the thermodynamics of the strong interaction in cold and dense matter, and predict a surface tension of Sigma ~ 5--15 MeV/fm^2, well below previous estimates. Including temperature effects and vacuum logarithmic corrections, we find a clear competition betw...

  10. Surface tension and specific heat of liquid Ni70.2Si29.8 alloy

    Institute of Scientific and Technical Information of China (English)

    WANG Haipeng; WEI Bingbo

    2005-01-01

    The surface tension and specific heat of stable and metastable liquid Ni70.2Si29.8 eutectic alloy were measured by electromagnetic levitation oscillating drop method and drop calorimetry. The surface tension depends on temperature linearly within the experimental undercooling regime of 0-182 K (0.12 TE). Its value is 1.693 N·m-1 at the eutectic temperature of 1488 K, and the temperature coefficient is -4.23×10-4 N·m-1·K-1. For the specific heat measurement, the maximum undercooling is up to 253 K (0.17 TE). The specific heat is determined as a polynomial function of temperature in the experimental temperature regime. On the basis of the measured data of surface tension and specific heat, the temperature-dependent density, excess volume and sound speed of liquid Ni70.2Si29.8 alloy are predicted theoretically.

  11. Surface tensions in horizon thermodynamics of Anti-de Sitter and de Sitter spacetimes

    CERN Document Server

    Chen, Deyou; Tao, Jun

    2016-01-01

    Adopting the surface tensions, we review the horizon thermodynamics of a Reissner-Nordstrom Anti-de Sitter black hole and a pure de Sitter spacetime. The modified first laws of thermodynamics, which obeys the corresponding Smarr relations, are gotten. For the black hole, the law is written as $\\delta E = T \\delta S - \\sigma\\delta A$ when the cosmological constant is fixed, where $E$ and $\\sigma$ are the Misner-Sharp mass and the surface tension, respectively. Treating the cosmological constant as an variable associated to the pressure, we rewrite the law as $\\delta E_0 = T \\delta S - \\sigma_{eff}\\delta A +V\\delta P$. The effective surface tension and pressure are obtained. The form of the modified first law of the de Sitter spacetime is different from that of the black hole.

  12. A new curvature technique calculation for surface tension contribution in PLIC-VOF method

    Science.gov (United States)

    Martinez, J.-M.; Chesneau, X.; Zeghmati, B.

    2006-01-01

    The volume of fluid (VOF) methods have been used for numerous numerical simulations. Among these techniques used to define the moving interface, the piecewise linear interface reconstruction (PLIC-VOF) is one of the most accurate. A study of the superficial tension impact on two-phase flow with free surface is presented. A new method based on direct staggered grid is developped to include surface tension in PLIC-VOF. The new numerical curvature calculation method doesn't need smoothed colour function and leads to less “spurious current”. This technique is applied to the calculus of surface tension force in the case of the rise of air bubble in viscous liquid and the fall of liquid drop in the same liquid on free surface. Droplets, thin layer and capillarity waves are observed after the free surface rupture for different Bond number. The influence of surface tension calculus is then obvioused and when the drop hit the free surface, wavelets propagate toward the virtual boundaries imposed.

  13. Density, Molar Volume, and Surface Tension of Liquid Al-Ti

    Science.gov (United States)

    Wessing, Johanna Jeanette; Brillo, Jürgen

    2017-02-01

    Al-Ti-based alloys are of enormous technical relevance due to their specific properties. For studies in atomic dynamics, surface physics and industrial processing the precise knowledge of the thermophysical properties of the liquid phase is crucial. In the present work, we systematically measure mass density, ρ (g cm-3), and the surface tension, γ (N m-1), as functions of temperature, T, and compositions of binary Al-Ti melts. Electromagnetic levitation in combination with the optical dilatometry method is used for density measurements and the oscillating drop method for surface tension measurements. It is found that, for all compositions, density and surface tension increase linearly upon decreasing temperature in the liquid phase. Within the Al-Ti system, we find the largest values for pure titanium and the smallest for pure aluminum, which amount to ρ(L,Ti) = 4.12 ± 0.04 g cm-3 and γ(L,Ti) = 1.56 ± 0.02 N m-1; and ρ(L,Al) = 2.09 ± 0.01 g cm-3 and γ(L,Al) = 0.87 ± 0.06 N m-1, respectively. The data are analyzed concerning the temperature coefficients, ρ T and γ T, excess molar volume, V E, excess surface tension, γ E, and surface segregation of the surface active component, Al. The results are compared with thermodynamic models. Generally, it is found that Al-Ti is a highly nonideal system.

  14. Accuracy of surface tension measurement from drop shapes: the role of image analysis.

    Science.gov (United States)

    Kalantarian, Ali; Saad, Sameh M I; Neumann, A Wilhelm

    2013-11-01

    Axisymmetric Drop Shape Analysis (ADSA) has been extensively used for surface tension measurement. In essence, ADSA works by matching a theoretical profile of the drop to the extracted experimental profile, taking surface tension as an adjustable parameter. Of the three main building blocks of ADSA, i.e. edge detection, the numerical integration of the Laplace equation for generating theoretical curves and the optimization procedure, only edge detection (that extracts the drop profile line from the drop image) needs extensive study. For the purpose of this article, the numerical integration of the Laplace equation for generating theoretical curves and the optimization procedure will only require a minor effort. It is the aim of this paper to investigate how far the surface tension accuracy of drop shape techniques can be pushed by fine tuning and optimizing edge detection strategies for a given drop image. Two different aspects of edge detection are pursued here: sub-pixel resolution and pixel resolution. The effect of two sub-pixel resolution strategies, i.e. spline and sigmoid, on the accuracy of surface tension measurement is investigated. It is found that the number of pixel points in the fitting procedure of the sub-pixel resolution techniques is crucial, and its value should be determined based on the contrast of the image, i.e. the gray level difference between the drop and the background. On the pixel resolution side, two suitable and reliable edge detectors, i.e. Canny and SUSAN, are explored, and the effect of user-specified parameters of the edge detector on the accuracy of surface tension measurement is scrutinized. Based on the contrast of the image, an optimum value of the user-specified parameter of the edge detector, SUSAN, is suggested. Overall, an accuracy of 0.01mJ/m(2) is achievable for the surface tension determination by careful fine tuning of edge detection algorithms.

  15. Quantitative Structure-Property Relationship on Prediction of Surface Tension of Nonionic Surfactants

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A quantitative structure-property relationship (QSPR) study has been made for the prediction of the surface tension of nonionic surfactants in aqueous solution.The regressed model includes a topological descriptor,the Kier & Hall index of zero order (KH0) of the hydrophobic segment of surfactant and a quantum chemical one,the heat of formation () of surfactant molecules.The established general QSPR between the surface tension and the descriptors produces a correlation coefficient of multiple determination,=0.9877,for 30 studied nonionic surfactants.

  16. Calculation of Surface Tensions of Polar Mixtures with a Simplified Gradient Theory Model

    DEFF Research Database (Denmark)

    Zuo, You-Xiang; Stenby, Erling Halfdan

    1996-01-01

    Key Words: Thermodynamics, Simplified Gradient Theory, Surface Tension, Equation of state, Influence Parameter.In this work, assuming that the number densities of each component in a mixture across the interface between the coexisting vapor and liquid phases are linearly distributed, we developed...... a simplified gradient theory (SGT) model for computing surface tensions. With this model, it is not required to solve the time-consuming density profile equations of the gradient theory model. The SRK EOS was applied to calculate the properties of the homogeneous fluid. First, the SGT model was used to predict...

  17. A collocation method for surface tension calculations with the density gradient theory

    DEFF Research Database (Denmark)

    Larsen, Peter Mahler; Maribo-Mogensen, Bjørn; Kontogeorgis, Georgios M.

    2016-01-01

    Surface tension calculations are important in many industrial applications and over a wide range of temperatures, pressures and compositions. Empirical parachor methods are not suitable over a wide condition range and the combined use of density gradient theory with equations of state has been...... proposed in literature. Often, many millions of calculations are required in the gradient theory methods, which is computationally very intensive. In this work, we have developed an algorithm to calculate surface tensions an order of magnitude faster than the existing methods, with no loss of accuracy...

  18. Surface tension measurements of aqueous ammonium chloride (NH4Cl) in air

    Science.gov (United States)

    Lowry, S. A.; Mccay, M. H.; Mccay, T. D.; Gray, P. A.

    1989-01-01

    Aqueous NH4Cl's solidification is often used to model metal alloy solidification processes. The present determinations of the magnitude of the variation of aqueous NH4Cl's surface tension as a function of both temperature and solutal concentration were conducted at 3, 24, and 40 C over the 72-100 wt pct water solutal range. In general, the surface tension increases 0.31 dyn/cm per percent decrease in wt pct of water, and decreases 0.13 dyn/cm for each increase in deg C. Attention is given to the experimental apparatus employed.

  19. Cloud droplet activation and surface tension of mixtures of slightly soluble organics and inorganic salt

    Directory of Open Access Journals (Sweden)

    S. Henning

    2004-11-01

    Full Text Available Critical supersaturations for internally mixed particles of adipic acid, succinic acid and sodium chloride were determined experimentally for dry particles sizes in the range 40–130 nm. Surface tensions of aqueous solutions of the dicarboxylic acids and sodium chloride corresponding to concentrations at activation were measured and parameterized as a function of carbon content. The activation of solid particles as well as solution droplets were studied and particle phase was found to be important for the critical supersaturation. Experimental data were modelled using Köhler theory modified to account for limited solubility and surface tension lowering.

  20. An adaptive finite element method for simulating surface tension with the gradient theory of fluid interfaces

    KAUST Repository

    Kou, Jisheng

    2014-01-01

    The gradient theory for the surface tension of simple fluids and mixtures is rigorously analyzed based on mathematical theory. The finite element approximation of surface tension is developed and analyzed, and moreover, an adaptive finite element method based on a physical-based estimator is proposed and it can be coupled efficiently with Newton\\'s method as well. The numerical tests are carried out both to verify the proposed theory and to demonstrate the efficiency of the proposed method. © 2013 Elsevier B.V. All rights reserved.

  1. Controlling the Motion of Ferrofluid Droplets Using Surface Tension Gradients and Magnetoviscous Pinning.

    Science.gov (United States)

    Ody, T; Panth, M; Sommers, A D; Eid, K F

    2016-07-12

    This work demonstrates the controlled motion and stopping of individual ferrofluid droplets due to a surface tension gradient and a uniform magnetic field. The surface tension gradients are created by patterning hydrophilic aluminum regions, shaped as wedges, on a hydrophobic copper surface. This pattern facilitates the spontaneous motion of water-based ferrofluid droplets down the length of the wedge toward the more hydrophilic aluminum end due to a net capillarity force created by the underlying surface wettability gradient. We observed that applying a magnetic field parallel to the surface tension gradient direction has little or no effect on the droplet's motion, while a moderate perpendicular magnetic field can stop the motion altogether effectively "pinning" the droplet. In the absence of the surface tension gradient, droplets elongate in the presence of a parallel field but do not travel. This control of the motion of individual droplets might lend itself to some biomedical and lab-on-a-chip applications. The directional dependence of the magnetoviscosity observed in this work is believed to be the consequence of the formation of nanoparticle chains in the fluid due to the existence of a minority of relatively larger magnetic particles.

  2. Quantitative differences in tissue surface tension influence zebrafish germ layer positioning.

    Science.gov (United States)

    Schötz, Eva-Maria; Burdine, Rebecca D; Jülicher, Frank; Steinberg, Malcolm S; Heisenberg, Carl-Philipp; Foty, Ramsey A

    2008-02-01

    This study provides direct functional evidence that differential adhesion, measurable as quantitative differences in tissue surface tension, influences spatial positioning between zebrafish germ layer tissues. We show that embryonic ectodermal and mesendodermal tissues generated by mRNA-overexpression behave on long-time scales like immiscible fluids. When mixed in hanging drop culture, their cells segregate into discrete phases with ectoderm adopting an internal position relative to the mesendoderm. The position adopted directly correlates with differences in tissue surface tension. We also show that germ layer tissues from untreated embryos, when extirpated and placed in culture, adopt a configuration similar to those of their mRNA-overexpressing counterparts. Down-regulating E-cadherin expression in the ectoderm leads to reduced surface tension and results in phase reversal with E-cadherin-depleted ectoderm cells now adopting an external position relative to the mesendoderm. These results show that in vitro cell sorting of zebrafish mesendoderm and ectoderm tissues is specified by tissue interfacial tensions. We perform a mathematical analysis indicating that tissue interfacial tension between actively motile cells contributes to the spatial organization and dynamics of these zebrafish germ layers in vivo.

  3. Adhesion of bubbles and drops to solid surfaces, and anisotropic surface tensions studied by capillary meniscus dynamometry

    NARCIS (Netherlands)

    Danov, Krassimir D.; Stanimirova, Rumyana D.; Kralchevsky, Peter A.; Marinova, Krastanka G.; Stoyanov, Simeon D.; Blijdenstein, Theodorus B.J.; Cox, Andrew R.; Pelan, Eddie G.

    2016-01-01

    Here, we review the principle and applications of two recently developed methods: the capillary meniscus dynamometry (CMD) for measuring the surface tension of bubbles/drops, and the capillary bridge dynamometry (CBD) for quantifying the bubble/drop adhesion to solid surfaces. Both methods are

  4. Fabrication of heterogeneous microlenses using self-surface tension

    Science.gov (United States)

    Chiang, Cheng-Han; Su, Guo-Dung J.

    2014-09-01

    Solar optical modeling tools are valuable for modeling and predicting the performance of solar technology systems. Four optical modeling tools were evaluated using the National Solar Thermal Test Facility heliostat field combined with flat plate receiver geometry as a benchmark. The four optical modeling tools evaluated were DELSOL, HELIOS, SolTrace, and Tonatiuh. All are available for free from their respective developers. DELSOL and HELIOS both use a convolution of the sunshape and optical errors for rapid calculation of the incident irradiance profiles on the receiver surfaces. SolTrace and Tonatiuh use ray-tracing methods to intersect the reflected solar rays with the receiver surfaces and construct irradiance profiles. We found the ray-tracing tools, although slower in computation speed, to be more flexible for modeling complex receiver geometries, whereas DELSOL and HELIOS were limited to standard receiver geometries such as flat plate, cylinder, and cavity receivers. We also list the strengths and deficiencies of the tools to show tool preference depending on the modeling and design needs. We provide an example of using SolTrace for modeling nonconventional receiver geometries. The goal is to transfer the irradiance profiles on the receiver surfaces calculated in an optical code to a computational fluid dynamics code such as ANSYS Fluent. This approach eliminates the need for using discrete ordinance or discrete radiation transfer models, which are computationally intensive, within the CFD code. The irradiance profiles on the receiver surfaces then allows for thermal and fluid analysis on the receiver.

  5. Effect of Undulations on Surface Tension in Simulated Bilayers

    NARCIS (Netherlands)

    Marrink, S.J.; Mark, A.E.

    2001-01-01

    To understand the effect of the finite size of simulation cells on the equilibrium properties of bilayers, an extensive series of glycerolmonoolein bilayer molecular dynamics simulations in which the surface area and system size were systematically changed have been conducted. Systems ranging from

  6. SURFACE TENSION OF MOLTEN IF STEEL CONTAINING Ti AND ITS INTERFACIAL PROPERTIES WITH SOLID ALUMINA

    Institute of Scientific and Technical Information of China (English)

    L.C. Zhong; M. Zeze; K. Mukai

    2004-01-01

    Surface tension of molten IF steel containing Ti and contact angle between the liquid steel and solid alumina were measured with sessile droplet method under Ar gas atmosphere at 1500, 1575 and 1600℃. The results show that titanium decreases the surface tension of the molten IF steel and the contact angle. The interfacial tension between the molten IF steel containing Ti and solid alumina decreases with increase in titanium content. The work of adhesion between molten IF steel containing Ti and solid alumina decreases slightly at 1550℃, but increases at 1600℃ with increasing titanium content. It can be deduced that fine bubbles and fine alumina inclusions are easily entrapped in solidifying interface for IF steel containing Ti.

  7. Motion driven by the interface. [pendant drop surface tension in microgravity

    Science.gov (United States)

    Jayaraj, K.; Cole, R.; Subramanian, R. S.

    1983-01-01

    Due to the reduction in buoyant forces aboard orbiting spacecraft such as the Space Shuttle, fluid motion driven by gradients in interfacial tension will be important in the processing of materials in space. In this paper, preliminary results from a study of surface tension driven flow in a pendant drop are reported. The drop is heated from above, and the resulting temperature gradients on the drop surface give rise to interfacial tension gradients. These, in turn, drive a circulation in the drop which is made visible by suitable tracers. The velocities are measured using a video technique, and the data on core velocities are found to agree well with results from a predictive theoretical model.

  8. Constrained sessile drop as a new configuration to measure low surface tension in lung surfactant systems.

    Science.gov (United States)

    Yu, Laura M Y; Lu, James J; Chan, Yawen W; Ng, Amy; Zhang, Ling; Hoorfar, Mina; Policova, Zdenka; Grundke, Karina; Neumann, A Wilhelm

    2004-08-01

    Existing methodology for surface tension measurements based on drop shapes suffers from the shortcoming that it is not capable to function at very low surface tension if the liquid dispersion is opaque, such as therapeutic lung surfactants at clinically relevant concentrations. The novel configuration proposed here removes the two big restrictions, i.e., the film leakage problem that is encountered with such methods as the pulsating bubble surfactometer as well as the pendant drop arrangement, and the problem of the opaqueness of the liquid, as in the original captive bubble arrangement. A sharp knife edge is the key design feature in the constrained sessile drop that avoids film leakage at low surface tension. The use of the constrained sessile drop configuration in conjunction with axisymmetric drop shape analysis to measure surface tension allows complete automation of the setup. Dynamic studies with lung surfactant can be performed readily by changing the volume of a sessile drop, and thus the surface area, by means of a motor-driven syringe. To illustrate the validity of using this configuration, experiments were performed using an exogenous lung surfactant preparation, bovine lipid extract surfactant (BLES) at 5.0 mg/ml. A comparison of results obtained for BLES at low concentration between the constrained sessile drop and captive bubble arrangement shows excellent agreement between the two approaches. When the surface area of the BLES film (0.5 mg/ml) was compressed by about the same amount in both systems, the minimum surface tensions attained were identical within the 95% confidence limits.

  9. Effect of temperature and concentration on the surface tension of chia seed mucilage

    Science.gov (United States)

    Fu, Yuting; Arye, Gilboa

    2017-04-01

    The production of mucilage by the seed coat during hydration is a common adaptation of many different plant species. The mucilage may play many ecological roles in adaptation and seed germination in diverse environments, especially in extreme desert conditions. The major compound of the seed mucilage is polysaccharides (e.g. pectins and hemicelluloses), which makes it highly hydrophilic. Consequently, it can hydrate quickly in the presence of water; forming a gel like coating surrounding the seed. However, the seed mucilage also reported to contain small amounts of protein and lipid which may exhibit surface activity at the water-air interface. As a result, decay in the surface tension of water can be occur and consequently a reduction in soil capillary pressure. This in turn may affect the water retention and transport during seed germination. The physical properties of the seeds mucilage have been studied mainly in conjunction with its rheological properties. To the best of our knowledge, its surface activity at the water-air interface has been reported mainly in the realms of food engineering, using a robust method of extraction. The main objective of this study was to quantify the effect of temperature and concentration on the surface tension of seed mucilage. The mucilage in this study was extracted from chia (Salvia hispanica L.) seeds, using distilled water (1:20 w/w) by shaking for 12 h at 4°C. The extracts were freeze dried after centrifuge (5000rpm for 20min). Fresh samples of different concentrations, ranging from 0.5 to 6 mg/ml, were prepared before each surface tension measurements. The equilibrium surface tension was measured by the Wilhelmy plate method using a tensiometer (DCAT 11, Data Physics) with temperature control unit. For a given mucilage concentration, surface tension measurements carried out at 5, 15, 25, 35, 45 °C. The quantitative and thermodynamic analysis of the results will be presented and discussed.

  10. Line Tension of Twist-Free Carbon Nanotube Lyotropic Liquid Crystal Microdroplets on Solid Surfaces.

    Science.gov (United States)

    Jamali, Vida; Biggers, Evan G; van der Schoot, Paul; Pasquali, Matteo

    2017-09-12

    Line tension, i.e., the force on a three-phase contact line, has been a subject of extensive research due to its impact on technological applications including nanolithography and nanofluidics. However, there is no consensus on the sign and magnitude of the line tension, mainly because it only affects the shape of small droplets, below the length scale dictated by the ratio of line tension to surface tension σ/τ. This ratio is related to the size of constitutive molecules in the system, which translates to a nanometer for conventional fluids. Here, we show that this ratio is orders of magnitude larger in lyotropic liquid crystal systems comprising micrometer-long colloidal particles. Such systems are known to form spindle-shaped elongated liquid crystal droplets in coexistence with the isotropic phase, with the droplets flattening when in contact with flat solid surfaces. We propose a method to characterize the line tension by fitting measured droplet shape to a macroscopic theoretical model that incorporates interfacial forces and elastic deformation of the nematic phase. By applying this method to hundreds of droplets of carbon nanotubes dissolved in chlorosulfonic acid, we find that σ/τ ∼ -0.84 ± 0.06 μm. This ratio is 2 orders of magnitude larger than what has been reported for conventional fluids, in agreement with theoretical scaling arguments.

  11. Heat Transfer in Bubble Columns with High Viscous and Low Surface Tension Media

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Wan Tae; Lim, Dae Ho; Kang, Yong [Chungnam National University, Daejeon (Korea, Republic of)

    2014-08-15

    Axial and overall heat transfer coefficients were investigated in a bubble column with relatively high viscous and low surface tension media. Effects of superficial gas velocity (0.02-0.1 m/s), liquid viscosity (0.1-3 Pa·s) and surface tension (66.1-72.9x10{sup -3} N/m) on the local and overall heat transfer coefficients were examined. The heat transfer field was composed of the immersed heater and the bubble column; a vertical heater was installed at the center of the column coaxially. The heat transfer coefficient was determined by measuring the temperature differences continuously between the heater surface and the column which was bubbling in a given operating condition, with the knowledge of heat supply to the heater. The local heat transfer coefficient increased with increasing superficial gas velocity but decreased with increasing axial distance from the gas distributor and liquid surface tension. The overall heat transfer coefficient increased with increasing superficial gas velocity but decreased with increasing liquid viscosity or surface tension. The overall heat transfer coefficient was well correlated in terms of operating variables such as superficial gas velocity, liquid surface tension and liquid viscosity with a correlation coefficient of 0.91, and in terms of dimensionless groups such as Nusselt, Reynolds, Prandtl and Weber numbers with a correlation of 0.92; h=2502U{sub G}{sup 0.236}{sub L}{sup -0.250}{sub L}{sup -}0{sup .028} Nu=3.25Re{sup 0.180}Pr{sup -0.067}We{sup 0.028}.

  12. Surface tension of heptane, decane, hexadecane, eicosane, and some of their binary mixtures

    DEFF Research Database (Denmark)

    Rolo, Lara I.; Caco, Ana I.; Queimada, Antonio;

    2002-01-01

    Surface tension measurements were performed by the Wilhelmy plate method. Measured systems included pure heptane, decane, hexadecane, eicosane, and some of their binary mixtures at temperatures from 293.15 K to 343.15 K with an average absolute deviation of 1.6%. The results were compared with a ...

  13. Evolution of melt-vapor surface tension in silicic volcanic systems: Experiments with hydrous melts

    Science.gov (United States)

    Mangan, M.; Sisson, T.

    2005-01-01

    We evaluate the melt-vapor surface tension (??) of natural, water-saturated dacite melt at 200 MPa, 950-1055??C, and 4.8-5.7 wt % H2O. We experimentally determine the critical supersaturation pressure for bubble nucleation as a function of dissolved water and then solve for ?? at those conditions using classical nucleation theory. The solutions obtained give dacite melt-vapor surface tensions that vary inversely with dissolved water from 0.042 (??0.003) J m-2 at 5.7 wt% H2O to 0.060 (??0.007) J m-2 at 5.2 wt% H2O to 0.073 (??0.003) J m-2 at 4.8 wt% H2O. Combining our dacite results with data from published hydrous haplogranite and high-silica rhyolite experiments reveals that melt-vapor surface tension also varies inversely with the concentration of mafic melt components (e.g., CaO, FeOtotal, MgO). We develop a thermodynamic context for these observations in which melt-vapor surface tension is represented by a balance of work terms controlled by melt structure. Overall, our results suggest that cooling, crystallization, and vapor exsolution cause systematic changes in ?? that should be considered in dynamic modeling of magmatic processes.

  14. The role of surface tension on the elastic decohesion of polymeric filaments

    DEFF Research Database (Denmark)

    Rasmussen, Henrik K.; Hassager, Ole

    2001-01-01

    We simulate the rapid extension of polymeric filaments between parallel plates with special attention to the role of surface tension in the symmetry breaking aximuthal instability that may occur near the end plates. The instability is viewed as a precursor to the eventual elastic decohesion of th...

  15. On surface tension of a bubble under presence of electrostatic force

    Directory of Open Access Journals (Sweden)

    Chen Rou-Xi

    2015-01-01

    Full Text Available The surface tension of a bubble is described by Young-Laplace equation, which becomes, however, invalid under the presence of electrostatic force, and a modified one is obtained, which can be widely applied for Bubbfil spinning process.

  16. Measurement and Modeling of Surface Tensions of Asymmetric Systems: Heptane, Eicosane, Docosane, Tetracosane and their Mixtures

    DEFF Research Database (Denmark)

    Queimada, Antonio; Silva, Filipa A.E; Caco, Ana I.;

    2003-01-01

    To extend the surface tension database for heavy or asymmetric n-alkane mixtures, measurements were performed using the Wilhelmy plate method. Measured systems included the binary mixtures heptane + eicosane, heptane + docosane and heptane + tetracosane and the ternary mixture heptane + eicosane...

  17. Characterization of the surface tension and solubility parameter of epoxy resin by using inverse gas chromatography.

    Science.gov (United States)

    Shi, Fenghui; Dai, Zhishuang; Zhang, Baoyan

    2010-07-01

    Inverse gas chromatography (IGC) was used to measure the surface tension and solubility parameter of E51 epoxy resin in this work. By using the Schultz method, decane, nonane, octane and heptane were chosen as the neutral probes to calculate the dispersive surface tensions (gamma(D)). Based on the Good-van Oss equation, the specific surface tension (gamma(SP)) of E51 epoxy resin was calculated with the acidic probe of dichloromethane and the basic probe of toluene. The results showed that the gamma(D) and gamma(SP) of the E51 resin decreased linearly with the increase of temperature. According to the Flory-Huggins parameters (chi) between the resin and a series of probes, the solubility parameters (delta) of E51 resin at different temperatures were estimated using the method developed by DiPaola-Baranyi and Guillet. It was found that the values of delta of the E51 resin were 11.78, 11.57, 11.48 and 11.14 MPa1/2 at 30, 40, 50 and 60 degrees C, respectively. The dispersive component (delta(D)) and the specific component (delta(SP)) of solubility parameter at different temperatures of the E51 resin were investigated according to the relationships between surface tension, cohesion energy and solubility parameter. The results showed that the values of delta(D) were higher than those of delta(SP) for the epoxy resin, and both of them decreased with the increase of temperature.

  18. Dynamic surface tension measured with an integrated sensor-actuator using electrolytically generated gas bubbles

    NARCIS (Netherlands)

    Olthuis, Wouter; Volanschi, Alex; Bergveld, Piet

    1998-01-01

    In this paper, a new, simple method to determine dynamic surface tension in aqueous solutions is reported, explained and experimentally verified. By function integration, a small device is obtained. Apart from control and interface electronics no external components or systems are necessary. Instead

  19. Dynamic surface tension measured with an integrated sensor-actuator device using electrolytically generated gas bubbles

    NARCIS (Netherlands)

    Olthuis, Wouter; Volanschi, Alex; Bergveld, Piet

    1997-01-01

    In this paper, a new, simple method to determine dynamic surface tension in aqueous solutions is reported, explained and experimentally verified. By function integration, a small device is obtained; apart from control and interface electronics no external components or systems are necessary. Instead

  20. Development of corresponding states model for estimation of the surface tension of chemical compounds

    DEFF Research Database (Denmark)

    Gharagheizi, Farhad; Eslamimanesh, Ali; Sattari, Mehdi;

    2013-01-01

    include critical temperature or temperature/critical volume/acentric factor/critical pressure/reduced temperature/reduced normal boiling point temperature/molecular weight of the compounds. Around 1,300 surface tension data of 118 random compounds are used for developing the first model (a four...

  1. 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.

  2. Fowler's approximation for the surface tension and surface energy of Lennard-Jones fluids revisited

    Energy Technology Data Exchange (ETDEWEB)

    Mulero, A [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain); Galan, C [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain); Cuadros, F [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain)

    2003-04-16

    We present a detailed study of the validity of Fowler's approximation for calculating the surface tension and the surface energy of Lennard-Jones fluids. To do so, we consider three different explicit analytical expressions for the radial distribution function (RDF), including one proposed by our research group, together with very accurate expressions for the liquid and vapour densities, also proposed by our group. The calculation of the surface tension from the direct correlation function using both the Percus-Yevick and the hypernetted-chain approximations is also considered. Finally, our results are compared with those obtained by other authors by computer simulations or through relevant theoretical approximations. In particular, we consider the analytical expression proposed by Kalikmanov and Hofmans (1994 J. Phys.: Condens. Matter 6 2207-14) for the surface tension. Our results indicate that the values for the surface energy in Fowler's approximation obtained by other authors are adequate, and can be calculated from the RDF models. For the surface tension, however, the values considered as valid in previous works seem to be incorrect. The correct values can be obtained from our model for the RDF or from the Kalikmanov and Hofmans expression with suitable inputs.

  3. In situ droplet surface tension and viscosity measurements in gas metal arc welding

    Science.gov (United States)

    Bachmann, B.; Siewert, E.; Schein, J.

    2012-05-01

    In this paper, we present an adaptation of a drop oscillation technique that enables in situ measurements of thermophysical properties of an industrial pulsed gas metal arc welding (GMAW) process. Surface tension, viscosity, density and temperature were derived expanding the portfolio of existing methods and previously published measurements of surface tension in pulsed GMAW. Natural oscillations of pure liquid iron droplets are recorded during the material transfer with a high-speed camera. Frame rates up to 30 000 fps were utilized to visualize iron droplet oscillations which were in the low kHz range. Image processing algorithms were employed for edge contour extraction of the droplets and to derive parameters such as oscillation frequencies and damping rates along different dimensions of the droplet. Accurate surface tension measurements were achieved incorporating the effect of temperature on density. These are compared with a second method that has been developed to accurately determine the mass of droplets produced during the GMAW process which enables precise surface tension measurements with accuracies up to 1% and permits the study of thermophysical properties also for metals whose density highly depends on temperature. Thermophysical properties of pure liquid iron droplets formed by a wire with 1.2 mm diameter were investigated in a pulsed GMAW process with a base current of 100 A and a pulse current of 600 A. Surface tension and viscosity of a sample droplet were 1.83 ± 0.02 N m-1 and 2.9 ± 0.3 mPa s, respectively. The corresponding droplet temperature and density are 2040 ± 50 K and 6830 ± 50 kg m-3, respectively.

  4. Design of a vapor-liquid-equilibrium, surface tension, and density apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, C.D.; Outcalt, S.L. [National Institute of Standards and Technology, Boulder, CO (United States)

    1997-12-31

    The design and performance of a unique vapor-liquid equilibrium (VLE) apparatus with density and surface tension capabilities is presented. The apparatus operates at temperatures ranging from 218 to 423 K, at pressures to 17 MPa, at densities to 1100 kg/m{sup 3}, and at surface tensions ranging from 0.1 to 75 mN/m. Temperatures are measured with a precision of {+-}0.02 K, pressures with a precision of {+-}0.1% of full scale, densities with a precision of {+-}0.5 kg/m{sup 3}, surface tensions with a precision of {+-}0.2 mN/m, and compositions with a precision of {+-}0.005 mole fraction. The apparatus is designed to be both accurate and versatile. Capabilities include: (1) the ability to operate the apparatus as a bubble point pressure or an isothermal pressure-volume-temperature (PVT) apparatus, (2) the ability to measure densities and surface tensions of the coexisting phases, and (3) the ability for either trapped or capillary sampling. We can validate our VLE and density data by measuring PVT or bubble point pressures in the apparatus. The use of the apparatus for measurements of VLE, densities, and surface tensions over wide ranges of temperature and pressure is important in equation of state and transport property model development. The use of different sampling procedures allows measurement of a wider variety of fluid mixtures. VLE measurements on the alternative refrigerant system R32/134a are presented and compared to literature results to verify the performance of the apparatus.

  5. Development of Maximum Bubble Pressure Method for Surface Tension Measurement of High Viscosity Molten Silicate

    Science.gov (United States)

    Takeda, Osamu; Iwamoto, Hirone; Sakashita, Ryota; Iseki, Chiaki; Zhu, Hongmin

    2017-07-01

    A surface tension measurement method based on the maximum bubble pressure (MBP) method was developed in order to precisely determine the surface tension of molten silicates in this study. Specifically, the influence of viscosity on surface tension measurements was quantified, and the criteria for accurate measurement were investigated. It was found that the MBP apparently increased with an increase in viscosity. This was because extra pressure was required for the flowing liquid inside the capillary due to viscous resistance. It was also expected that the extra pressure would decrease by decreasing the fluid velocity. For silicone oil with a viscosity of 1000 \\hbox {mPa}{\\cdot }\\hbox {s}, the error on the MBP could be decreased to +1.7 % by increasing the bubble detachment time to 300 \\hbox {s}. However, the error was still over 1 % even when the bubble detachment time was increased to 600 \\hbox {s}. Therefore, a true value of the MBP was determined by using a curve-fitting technique with a simple relaxation function, and that was succeeded for silicone oil at 1000 \\hbox {mPa}{\\cdot } \\hbox {s} of viscosity. Furthermore, for silicone oil with a viscosity as high as 10 000 \\hbox {mPa}{\\cdot }\\hbox {s}, the apparent MBP approached a true value by interrupting the gas introduction during the pressure rising period and by re-introducing the gas at a slow flow rate. Based on the fundamental investigation at room temperature, the surface tension of the \\hbox {SiO}2-40 \\hbox {mol}%\\hbox {Na}2\\hbox {O} and \\hbox {SiO}2-50 \\hbox {mol}%\\hbox {Na}2\\hbox {O} melts was determined at a high temperature. The obtained value was slightly lower than the literature values, which might be due to the influence of viscosity on surface tension measurements being removed in this study.

  6. Derivation of a viscous KP including surface tension, and related equations

    CERN Document Server

    Meur, Hervé Le

    2015-01-01

    The aim of this article is to derive surface wave models in the presence of surface tension and viscosity. Using the Navier-Stokes equations with a free surface, flat bottom and surface tension, we derive the viscous 2D Boussinesq system with a weak transverse variation. The assumed transverse variation is on a larger scale than along the main propagation direction. This Boussinesq system is only an intermediate result that enables us to derive the Kadomtsev-Petviashvili (KP) equation which is a 2D generalization of the KdV equation. In addition, we get the 1D KdV equation, and lastly the Boussinesq equation. All these equations are derived for non-vanishing initial conditions.

  7. Tension induced surface plasmon-polaritons at graphene-based structure

    Science.gov (United States)

    Khalandi, G.; Namdar, A.; Entezar, S. Roshan

    2017-02-01

    Dispersion properties and field distributions of TM (or p-polarized) surface plasmon-polaritons have been investigated in the system that a strained graphene sheet cladded by two dielectrics. The outcomes show that graphene TM surface plasmon-polaritons are bound confined modes, and the field components penetrate into the dielectric layers in the rang that is very smaller than the wavelength in the free space. At low photon energies, when the tension is along the zigzag (armchair) direction and parallel (perpendicular) to the tangential electric field, the wavelength, propagation length and penetration depth of TM surface plasmon-polaritons increase (decrease) with increasing the strain. Changing the angle between the tension direction and tangential electric field at cases with the constant strain, cause to existence of TM surface plasmon-polaritons in the wider range of frequency.

  8. Spreading of oil on water in the surface-tension regime

    Energy Technology Data Exchange (ETDEWEB)

    Camp, D.W.; Berg, J.C.

    1987-11-01

    Data which describe the unidirectional spreading of several pure oils and oil-surfactant mixtures on water in the surface-tension regime are reported. Leading-edge position and profiles of velocity, thickness and film tension are given as functions of time. The data are consistent with the numerical similarity solution of Foda and Cox (1980), although the measured dependence of the film tension on the film thickness often differs from the equilibrium relationship. The configuration of the oil film near the spreading origin may be either a coherent multimolecular layer or a multitude of thinning, outward-moving lenses surrounded by monolayer. The pure oils show an acceleration zone connecting the slow-moving inner region to a fast-moving outer region, while the oil-surfactant mixtures show a much more gradual increase in film velocity.

  9. Account for the surface tension in hydraulic modeling of the weir with a sharp threshold

    Directory of Open Access Journals (Sweden)

    Medzveliya Manana Levanovna

    Full Text Available In the process of calculating and simulating water discharge in free channels it is necessary to know the flow features in case of small values of Reynolds and Weber numbers. The article considers the influence of viscosity and surface tension on the coefficient of a weir flow with sharp threshold. In the article the technique of carrying out experiments is stated, the equation is presented, which considers the influence of all factors: pressure over a spillway threshold, threshold height over a course bottom, speed of liquid, liquid density, dynamic viscosity, superficial tension, gravity acceleration, unit discharge, the width of the course. The surface tension and liquid density for the applied liquids changed a little. In the rectangular tray (6000x100x200 spillway with a sharp threshold was established. It is shown that weir flow coefficient depends on Reynolds number (in case Re < ~ 2000 and Webers number. A generalized expression for determining weir flow coefficient considering the influence of the forces of viscosity and surface tension is received.

  10. Surface tension of polytetrafluoroethylene and its wetting by aqueous solution of some surfactants and their mixtures

    Science.gov (United States)

    Mańko, Diana; Zdziennicka, Anna; Jańczuk, Bronisław

    2017-01-01

    Measurements of the contact angle of aqueous solution of rhamnolipid (RL) mixture with n-octyl-β-D-glucopyranoside (OGP), Triton X-100 (TX-100) or/and sodium dodecylsulfate (SDDS) on polytetrafluoroethylene (PTFE) were made. To this aim there was used a plate whose surface topography was analyzed by means of optical profilometry method. Additionally, plate surface chemistry was studied employing the Fourier transform infrared spectroscopy. The obtained values of contact angle were discussed based on the PTFE surface tension (γSV) as well as the Lifshitz-van der Waals component of the water surface tension (γWLW). The contact angle of aqueous solution of several surfactants and their mixtures on PTFE was also considered on the basis of γSV and γWLW . It occured that by using the values of γSV , γWLW and surface tension of the aqueous solution of surfactants and their mixtures, the contact angle on PTFE can be predicted. It also occured that changes of adhesion tension of aqueous solutions of surfactants as a function of their concentration can be determined by the exponential function of the first or second order. Using such functions Gibbs surface excess concentration of surfactants at the PTFE-water interface, mole fraction of surfactant in the mixed monolayer and fraction of the area occupied by given surfactants in the monolayer were determined. Gibbs surface free energy of adsorption of a given surfactant in the presence of another one and adhesion work of the aqueous solution of surfactants to the PTFE surface were also evaluated.

  11. 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.

  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) are essentia...... of interfacial tension becomes significant for particles with a radius of similar to 5 nm, when the area per molecule in the surface region is...

  13. Surface Tension Estimates for Droplet Formation in Slurries with Low Concentrations of Hydrophobic Particles, Polymer Flocculants or Surface-Active Contaminants

    Energy Technology Data Exchange (ETDEWEB)

    Gauglitz, Phillip A.; Mahoney, Lenna A.; Blanchard, Jeremy; Bamberger, Judith A.

    2011-06-10

    In support of the K-Basin project, Pacific Northwest National Laboratory (PNNL) was requested to evaluate the appropriate surface tension value to use in models predicting the formation of droplets from spray leaks of K-Basin slurries. The specific issue was whether it was more appropriate to use the surface tension of pure water in model predictions for all plausible spray leaks or to use a lower value. The surface tension of K-Basin slurries is potentially affected not only by particles but by low concentrations of nonionic polyacrylamide flocculant and perhaps by contaminants with surfactant properties, which could decrease the surface tension below that of water. A lower surface tension value typically results in smaller droplets being formed with a larger fraction of droplets in the respirable size range, so using the higher surface tension value of pure water is not conservative and thus needs a strong technical basis.

  14. The effects of nonuniform surface tension on the axisymmetric gravity-driven spreading of a thin liquid drop

    Directory of Open Access Journals (Sweden)

    E. Momoniat

    2005-01-01

    surface tension can be represented as a power law in r. The effect of this nonuniformity is to reduce the surface tension at the centre of the drop and increase it at the foot of the drop. This results in a deflection away from the solution for spreading under gravity only and the formation of a capillary ridge.

  15. Dynamics of surface tension driven mixing of an alcohol droplet with water

    Science.gov (United States)

    Dandekar, Raj; Pant, Anurag; Puthenveettil, Baburaj

    2016-11-01

    We study the flow induced by the surface tension driven spreading of an ethanol droplet of radius rd on the surface of a 5mm water layer, visualizing the flow using aluminium flakes on the surface of the water layer with backlighting and high speed imaging. The concentration of tracer aluminium particles was found to have no effect on the scaling law for spreading.The drop,when brought in contact with the water surface causes a local depression in surface tension ,resulting in a thin circular region to expand radially outwards.We observe that the dimensionless radius of the expanding front (r* =r/rd) scales with the dimensionless time (t* = μ rd/ Δγ) , as r* t*1/4,where μ is the viscosity of water and Δγ is the surface tension difference between water and the ethanol droplet.A scaling analysis taking the viscous and the marangoni forces into account explains the observed scaling law.Our observations differ from that in the case of continuous alcohol supply where the observed scaling law is r* t*1/2. The expanding front radius reaches a maximum value and then decreases with time.

  16. Surface tension driven processes densify and retain permeability in magma and lava

    Science.gov (United States)

    Kennedy, Ben M.; Wadsworth, Fabian B.; Vasseur, Jérémie; Ian Schipper, C.; Mark Jellinek, A.; von Aulock, Felix W.; Hess, Kai-Uwe; Kelly Russell, J.; Lavallée, Yan; Nichols, Alexander R. L.; Dingwell, Donald B.

    2016-01-01

    We offer new insights into how an explosive eruption can transition into an effusive eruption. Magma containing >0.2 wt% dissolved water has the potential to vesiculate to a porosity in excess of 80 vol.% at atmospheric pressure. Thus all magmas contain volatiles at depth sufficient to form foams and explosively fragment. Yet gas is often lost passively and effusive eruptions ensue. Magmatic foams are permeable and understanding permeability in magma is crucial for models that predict eruptive style. Permeability also governs magma compaction models. Those models generally imply that a reduction in magma porosity and permeability generates an increased propensity for explosivity. Here, our experimental results show that surface tension stresses drive densification without creating an impermeable 'plug', offering an additional explanation of why dense magmas can avoid explosive eruption. In both an open furnace and a closed autoclave, we subject pumice samples with initial porosity of ∼70 vol.% to a range of isostatic pressures (0.1-11 MPa) and temperatures (350-950 °C) relevant to shallow volcanic environments. Our experimental data and models constrain the viscosity, permeability, timescales, and length scales over which densification by pore-scale surface tension stresses competes with density-driven compaction. Where surface tension dominates the dynamics, densification halts at a plateau connected porosity of ∼25 vol.% for our samples. SEM, pycnometry and micro-tomography show that in this process (1) microporous networks are destroyed, (2) the relative pore network surface area decreases, and (3) a remaining crystal framework enhances the longevity of macro-pore connectivity and permeability critical for sustained outgassing. We propose that these observations are a consequence of a surface tension-driven retraction of viscous pore walls at areas of high bubble curvature (micro-vesicular network terminations), and that this process drives bulk

  17. Wetting Angle and Surface Tension of Germanium Melts on Different Substrate Materials

    Science.gov (United States)

    Kaiser, N.; Croell, A.; Szofran, F. R.; Benz, K. W.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    The sessile drop technique has been used to measure the wetting angle and the surface tension of molten germanium (Ge) on various substrate materials. Sapphire, fused silica, glassy carbon, graphite, SiC, carbon-based aerogel, pyrolytic boron nitride (pBN), AlN, Si3N4, and CVD diamond were used as substrate materials. In addition, the effects of different cleaning procedures and surface treatments on the wetting behavior were investigated. The highest wetting angles with values around 170 deg. were found for pBN substrates under active vacuum or with a slight overpressure of 5N Argon or forming gas (2% Hydrogen in 5N Argon). The measurement of the surface tension and its temperature dependence for Ge under a forming gas atmosphere resulted in gamma(T) = 591 - 0.077 (T-T(sub m).

  18. From density to interface fluctuations: the origin of wavelength dependence in surface tension.

    Science.gov (United States)

    Hiester, Thorsten

    2008-12-01

    The height-height correlation function for a fluctuating interface between two coexisting bulk phases is derived by means of general equilibrium properties of the corresponding density-density correlation function. A wavelength-dependent surface tension gamma(q) can be defined and expressed in terms of the direct correlation function c(r,r;{'}) , the equilibrium density profile rho_{0}(r) , and an operator which relates density to surface configurations. Neither the concept of an effective interface Hamiltonian nor the difference in pressure is needed to determine the general structure of the height-height correlations or gamma(q) , respectively. This result generalizes the Mecke-Dietrich surface tension gamma_{MD}(q) [Phys. Rev. E 59, 6766 (1999)] and modifies recently published criticism concerning gamma_{MD}(q) [Tarazona, Checa, and Chacón, Phys. Rev. Lett. 99, 196101 (2007)].

  19. The Role of Surface Tension in the Crystallization of Metal Halide Perovskites

    KAUST Repository

    Zhumekenov, Ayan A.

    2017-07-06

    The exciting intrinsic properties discovered in single crystals of metal halide perovskites still await their translation into optoelectronic devices. The poor understanding and control of the crystallization process of these materials are current bottlenecks retarding the shift towards single crystal-based optoelectronics. Here we theoretically and experimentally elucidate the role of surface tension in the rapid synthesis of perovskite single crystals by inverse temperature crystallization (ITC). Understanding the nucleation and growth mechanisms enabled us to exploit surface tension to direct the growth of monocrystalline films of perovskites (AMX3, where A = CH3NH3+ or MA; M = Pb2+, Sn2+; X = Br-, I-) on the solution surface. We achieve up to 1 cm2-sized monocrystalline films with thickness on the order of the charge carrier diffusion length (~5-10 µm). Our work paves the way to control the crystallization process of perovskites, including thin film deposition, which is essential to advance the performance benchmarks of perovskite optoelectronics.

  20. Contact angle and surface tension measurements of a five-ring polyphenyl ether

    Science.gov (United States)

    Jones, W. R., Jr.

    1986-01-01

    Contact angle measurements were performed for a five-ring polyphenyl ether isomeric mixture on M-50 steel in a dry nitrogen atmosphere. Two different techniques were used: (1) a tilting plate apparatus, and (2) a sessile drop apparatus. Measurements were made for the temperature range 25 to 190 C. Surface tension was measured by a differential maximum bubble pressure technique over the range 23 to 220 C in room air. The critical surface energy of spreading (gamma /sub c/) was determined for the polyphenyl ether by plotting the cosine of the contact angle (theta) versus the surface tension (gamma /sub LV/). The straight line intercept at cosine theta = 1 is defined as gamma (sub c). Gamma (sub c) was found to be 30.1 dyn/cm for the tilting plate technique and 31.3 dyn/cm for the sessile drop technique. These results indicate that the polyphenyl ether is inherently autophobic (i.e., it will not spread on its own surface film until its surface tension is less than gamma /sub c/). This phenomenon is discussed in light of the wettability and wear problems encountered with this fluid.

  1. Role of viscosity and surface tension of zebrafish embryonic tissues in tissue flows during gastrulation.

    Science.gov (United States)

    Schoetz, E. M.; Bacarian, T.; Steinberg, M. S.; Burdine, R. D.; Bialek, W.; Heisenberg, C. P.; Foty, R. A.; Julicher, F.

    2007-03-01

    At the onset of gastrulation in zebrafish, complex flows and cell movements occur, which are not well understood. Here, we study the material properties of zebrafish embryonic tissues which are important for the tissue dynamics. We found that these tissues behave viscoelastic and exhibit liquid-like properties on long time scales. They relax internal stress caused by compressive forces or, in the absence of external forces, round up and fuse into spheres to minimize their free surface. Quantitative differences in the adhesivity between different types of tissues result in their immiscibility and sorting behavior analogous to that of ordinary immiscible liquids. When mixed, cells segregate into discrete phases, and the position adopted correlates with differences in the aggregate surface tensions for these phases. Surface tensions were measured with a tissue surface tensiometer. Aggregates were compressed and their force response and shape were recorded as a function of time. From the analysis of the force-relaxation curves, we determined the surface tensions, relaxation times, tissue viscosities and shear moduli. Furthermore, by 4D-cell tracking, we measured kinetic parameters such as cell speed, directionality and persistence of cell movement.

  2. Role of surface tension and roughness on the wettability of Er:YAG laser irradiated dentin: In vitro study

    OpenAIRE

    2013-01-01

    Introduction: The aim of this “in vitro” study was to evaluate the role of surface tension and surface roughness in the wettability, considered essential for a good adhesion, comparing Er:YAG laser - to bur-prepared dentin.

  3. 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.

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

    Science.gov (United States)

    Garrick, Daniel P.; Owkes, Mark; Regele, Jonathan D.

    2017-06-01

    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.

  5. Neutron-skin thickness determines the surface tension of a compressible nuclear droplet

    Science.gov (United States)

    Horiuchi, W.; Ebata, S.; Iida, K.

    2017-09-01

    We systematically investigate the neutron-skin thickness of neutron-rich nuclei within a compressible droplet model, which includes several parameters characterizing the surface tension and the equation of state (EOS) of asymmetric nuclear matter as well as corrections due to the surface diffuseness. Such a systematic analysis helps towards constraining the EOS parameters of asymmetric nuclear matter and the poorly known density dependence of the surface tension; the latter is estimated with help of available experimental data for the neutron and proton density distributions and the nuclear masses. Validity of the present approach is confirmed by calculating realistic density distributions of Ca, Ni, Zr, Sn, Yb, and Pb isotopes within a microscopic Skyrme-Hartree-Fock+BCS method for various sets of the effective nuclear force. Our macroscopic model accompanied by the diffuseness corrections works well in the sense that it well reproduces the evolution of the microscopically deduced neutron-skin thickness with respect to the neutron number for selected sets of the effective nuclear force. We find that the surface tension of the compressible nuclear droplet is a key to bridging a gap between microscopic and macroscopic approaches.

  6. Reactive processing of formaldehyde and acetaldehyde in aqueous aerosol mimics: surface tension depression and secondary organic products

    Directory of Open Access Journals (Sweden)

    Z. Li

    2011-07-01

    Full Text Available The reactive uptake of carbonyl-containing volatile organic compounds (cVOCs by aqueous atmospheric aerosols is a likely source of particulate organic material. The aqueous-phase secondary organic products of some cVOCs are surface-active. Therefore, cVOC uptake can lead to organic film formation at the gas-aerosol interface and changes in aerosol surface tension. We examined the chemical reactions of two abundant cVOCs, formaldehyde and acetaldehyde, in water and aqueous ammonium sulfate (AS solutions mimicking tropospheric aerosols. Secondary organic products were identified using Aerosol Chemical Ionization Mass Spectrometry (Aerosol-CIMS, and changes in surface tension were monitored using pendant drop tensiometry. Hemiacetal oligomers and aldol condensation products were identified using Aerosol-CIMS. A hemiacetal sulfate ester was tentatively identified in the formaldehyde-AS system. Acetaldehyde depresses surface tension to 65(±2 dyn cm−1 in pure water and 62(±1 dyn cm−1 in AS solutions. Surface tension depression by formaldehyde in pure water is negligible; in AS solutions, a 9 % reduction in surface tension is observed. Mixtures of these species were also studied in combination with methylglyoxal in order to evaluate the influence of cross-reactions on surface tension depression and product formation in these systems. We find that surface tension depression in the solutions containing mixed cVOCs exceeds that predicted by an additive model based on the single-species isotherms.

  7. Superficial composition in binary solid solutions A(B): Drastic effect of pure element surface tensions

    Science.gov (United States)

    Rolland, A.; Aufray, B.

    1985-10-01

    This paper deals with a comparative study of surface segragation of Pb and Ni respectively from Ag(Pb)(111) and Ag(Ni)(111) solid solutions. A high level of segregation of the solute is observed for both systems characterized by very low solute solubility. However, the superficial composition strongly depends on the relative surface tensions of the pure elements: the solute atoms are strictly on superficial sites when γ solute is smaller than γ solvent; in contrast uppermost layer consists purely of solvent when γ solute is greater than γ solvent. Two schematic distributions in close proximity to the surface are proposed in the last case.

  8. Application of the Zisman Critical Surface Tension Technique to Textile Materials Using Contact Angle Measurements

    Institute of Scientific and Technical Information of China (English)

    江红; 迟克栋; 吴慧莉

    2001-01-01

    This is the first one that applies the Zisman critical surface tension technique successfully to textile materials. It was accomplished by carefully determination of the contact angle of fabric. The deviation caused by the porous structure of the fabric will be taken into account. To do so, a Jens equation is applied, and the measured contact angles can be corrected. The surface porosity was determined by measurement and approximate calculation, and the chemical composition of the surface was characterized by means of attenuated total reflection Fourier-transform infrared(FTIR/ATR).

  9. Possible Evidence for a New Form of Liquid Buried in the Surface Tension of Supercooled Water

    Science.gov (United States)

    Rogers, T. Ryan; Leong, Kai-Yang; Wang, Feng

    2016-09-01

    Contrary to the historical data, several recent experiments indicate that the surface tension of supercooled water follows a smooth extrapolation of the IAPWS equation in the supercooled regime. It can be seen, however, that a small deviation from the IAPWS equation is present in the recent experimental measurements. It is shown with simulations using the WAIL water potential that the small deviation in the experimental data is consistent with the tail of an exponential growth in surface tension as temperature decreases. The emergence temperature, Te, of a substantial deviation from the IAPWS equation is shown to be 227 K for the WAIL water and 235 K for real water. Since the 227 K Te is close to the Widom line in WAIL water, we argue that real water at 235 K approaches a similar crossover line at one atmospheric pressure.

  10. Discrepancies over the onset of surfactant monomer aggregation interpreted by fluorescence, conductivity and surface tension methods

    Directory of Open Access Journals (Sweden)

    Maria de Fátima Carvalho Costa

    1998-06-01

    Full Text Available Molecular probe techniques have made important contributions to the determination of microstructure of surfactant assemblies such as size, stability, micropolarity and conformation. Conductivity and surface tension were used to determine the critical aggregation concentration (cac of polymer-surfactant complexes and the critical micellar concentration (cmc of aqueous micellar aggregates. The results are compared with those of fluorescent techniques. Several surfactant systems were examined, 1-butanol-sodium dodecylsulfate (SDS mixtures, solutions containing poly(ethylene oxide-SDS, poly(vinylpyrrolidone-SDS and poly(acrylic acid-alkyltrimethylammonium bromide complexes. We found differences between the cac and cmc values obtained by conductivity or surface tension and those obtained by techniques which use hydrophobic probe.

  11. Synthesis and Surface Tension Properties of Polyethyleneimine—Polyethylene Oxide Block Copolymers

    Institute of Scientific and Technical Information of China (English)

    张剑; LONNIE,Bryant

    2003-01-01

    This peper describes the synthesis,surface tension and dispersancy properties of block copolymer nonionic surfactants comprised of polyethyleneimine(PEI) and polyethlene oxide(PEO) blocks of selected lengths.These block copolymers were prepared by a threestep synthetic sequence.Firstly,PEO glycol was converted to its dimethanesulphonylester (dimesyl) derivative by reacting with methanesulphonyl chloride.Then a tri-block polymer was preparaed by the ring-opening polymerization of 2-methly-2-oxazoline(MeOZO)with the dimesyl PEO derivative.Lastly,linear PEI blocks were obtained by subsequent hydrolysis and purification.1H NMR spectra confirmed the structures of the intermediate,final products and their purities(>99%).The utility of these block copolymers is described in terms of their surface tension and clay dispersancy measurements as a function of copolymer chain and block length.

  12. Light Meets Water in Nonlocal Media: Surface Tension Analogue in Optics

    Science.gov (United States)

    Horikis, Theodoros P.; Frantzeskakis, Dimitrios J.

    2017-06-01

    Shallow water wave phenomena find their analogue in optics through a nonlocal nonlinear Schrödinger (NLS) model in 2 +1 dimensions. We identify an analogue of surface tension in optics, namely, a single parameter depending on the degree of nonlocality, which changes the sign of dispersion, much like surface tension does in the shallow water wave problem. Using multiscale expansions, we reduce the NLS model to a Kadomtsev-Petviashvili (KP) equation, which is of the KPII (KPI) type, for strong (weak) nonlocality. We demonstrate the emergence of robust optical antidark solitons forming Y -, X -, and H -shaped wave patterns, which are approximated by colliding KPII line solitons, similar to those observed in shallow waters.

  13. Surface Tension of Methanol as a Function of cut-off Radius and Temperature Controllers

    Science.gov (United States)

    Obeidat, Abdalla; Jaradat, Adnan; Hamdan, Bushra

    Molecular dynamics is used to calculate the surface tension of van Leeuwen methanol. The van Leeuwen model of methanol is chosen over other models of methanol, since this model is widely used to study nucleation at low temperature. Usually, scientists use the cut-off radius to be three order of magnitude of segment diameter. In this study, we varied the cut-off radius to estimate the best cut-off at which the surface tension reaches its plateau. After deciding the best cut-off radius for van der Waals and Coulomb interactions (CUT-OFF and PME were used for Coulomb interaction), we varied the temperature controller (van-Housen, Berendsen, and v-rescale) to decide the best temperature controller to be used to study methanol. In all simulations, Gromacs is used at T =200-300K with periodic boundary conditions in all dimensions. JUST.

  14. Digital image processing of sectorial oscillations for acoustically levitated drops and surface tension measurement

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    A type of non-axisymmetric oscillations of acoustically levitated drops is excited by modulating the ultrasound field at proper frequencies. These oscillations are recorded by a high speed camera and analyzed with a digital image processing method. They are demonstrated to be the third mode sectorial oscillations, and their frequencies are found to decrease with the increase of equatorial radius of the drops, which can be described by a modified Rayleigh equation. These oscillations decay exponentially after the cessation of ultrasound field modulation. The decaying rates agree reasonably with Lamb’s prediction. The rotating rate of the drops accompanying the shape oscillations is found to be less than 1.5 rounds per second. The surface tension of aqueous ethanol has been measured according to the modified Rayleigh equation. The results agree well with previous reports, which demonstrates the possible application of this kind of sectorial oscillations in noncontact measurement of liquid surface tension.

  15. A Synthetic Phased Array Surface Acoustic Wave Sensor for Quantifying Bolt Tension

    Directory of Open Access Journals (Sweden)

    Rasim Guldiken

    2012-09-01

    Full Text Available In this paper, we report our findings on implementing a synthetic phased array surface acoustic wave sensor to quantify bolt tension. Maintaining proper bolt tension is important in many fields such as for ensuring safe operation of civil infrastructures. Significant advantages of this relatively simple methodology is its capability to assess bolt tension without any contact with the bolt, thus enabling measurement at inaccessible locations, multiple bolt measurement capability at a time, not requiring data collection during the installation and no calibration requirements. We performed detailed experiments on a custom-built flexible bench-top experimental setup consisting of 1018 steel plate of 12.7 mm (½ in thickness, a 6.4 mm (¼ in grade 8 bolt and a stainless steel washer with 19 mm (¾ in of external diameter. Our results indicate that this method is not only capable of clearly distinguishing properly bolted joints from loosened joints but also capable of quantifying how loose the bolt actually is. We also conducted detailed signal-to-noise (SNR analysis and showed that the SNR value for the entire bolt tension range was sufficient for image reconstruction.

  16. Let’s not forget the critical role of surface tension in xylem water relations

    Science.gov (United States)

    Jean-Christophe Domec

    2011-01-01

    The widely supported cohesion–tension theory of water transport explains the importance of a continuous water column and the mechanism of long-distance ascent of sap in plants (Dixon 1914, Tyree 2003, Angeles et al. 2004). The evaporation of water from the surfaces of mesophyll cells causes the air–water interface to retreat into the cellulose matrix of the plant cell...

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

    Science.gov (United States)

    Colucci, Simone; Battaglia, Maurizio; Trigila, Raffaello

    2016-01-01

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

  18. The effects of surface tension on flooding in counter-current two-phase flow in an inclined tube

    Energy Technology Data Exchange (ETDEWEB)

    Deendarlianto [Department of Mechanical and Industrial Engineering, Faculty of Engineering, Gadjah Mada University, Jalan Grafika No.2 Yogyakarta 55281 (Indonesia); Forschungszentrum Dresden-Rossendorf e.V., Institute of Safety Research, P.O. Box 510 119, D-01314 Dresden (Germany); Ousaka, Akiharu [Department of Mechanical Engineering, The University of Tokushima, 2-1 Minami Josanjima, Tokushima 770-8506 (Japan); Indarto [Department of Mechanical and Industrial Engineering, Faculty of Engineering, Gadjah Mada University, Jalan Grafika No.2 Yogyakarta 55281 (Indonesia); Kariyasaki, Akira [Department of Chemical Engineering, Fukuoka University, 8-19-1, Jyonan-ku, Fukuoka 814-0180 (Japan); Lucas, Dirk; Vallee, Christophe [Forschungszentrum Dresden-Rossendorf e.V., Institute of Safety Research, P.O. Box 510 119, D-01314 Dresden (Germany); Vierow, Karen; Hogan, Kevin [Department of Nuclear Engineering Texas A and M University, 129 Zachry Engineering Center, 3133 TAMU College Station, TX 77843-3133 (United States)

    2010-10-15

    The purpose of the present study is to investigate the effects of surface tension on flooding phenomena in counter-current two-phase flow in an inclined tube. Previous studies by other researchers have shown that surface tension has a stabilizing effect on the falling liquid film under certain conditions and a destabilizing or unclear trend under other conditions. Experimental results are reported herein for air-water systems in which a surfactant has been added to vary the liquid surface tension without altering other liquid properties. The flooding section is a tube of 16 mm in inner diameter and 1.1 m length, inclined at 30-60 from horizontal. The flooding mechanisms were observed by using two high-speed video cameras and by measuring the time variation of liquid hold-up along the test tube. The results show that effects of surface tension are significant. The gas velocity needed to induce flooding is lower for a lower surface tension. There was no upward motion of the air-water interfacial waves upon flooding occurrence, even for lower a surface tension. Observations on the liquid film behavior after flooding occurred suggest that the entrainment of liquid droplets plays an important role in the upward transport of liquid. Finally, an empirical correlation for flooding velocities is proposed that includes functional dependencies on surface tension and tube inclination. (author)

  19. Modeling of ultrasound contrast agents bubble dynamics with modified surface tension coefficient

    Institute of Scientific and Technical Information of China (English)

    ZHENG LuJie; TU Juan; CHEN WeiZhong

    2009-01-01

    The current work proposes a model describing the dynamics of coated microbubbles, which simplifies the traditional three-layer model to a two-layer one by introducing a visco-elastic interface with variable surface tension coefficients to connect the gas zone and the liquid zone. In the modified model, the traditional two interfaces boundary conditions are combined into one to simplify the description of the bubble. Moreover, the surface tension coefficient is defined as a function of bubble radius with lower and upper limits, which are related to the buckling and rupture mechanisms of the bubble. Further discussion is made regarding the effects resulting from the change of the surface tension coefficient on bubble dynamics. The dynamic responses of Optison and Sonozoid microbubbles, measured experimentally based on light scattering technology (adapted from previously published work), are simulated using both classic three-layer models (e.g. Church's model) and simplified model. The resuits show that our simplified model works as well as the Church's model.

  20. Well-posedness for the Classical Stefan Problem and the Zero Surface Tension Limit

    Science.gov (United States)

    Hadžić, Mahir; Shkoller, Steve

    2016-11-01

    We develop a framework for a unified treatment of well-posedness for the Stefan problem with or without surface tension. In the absence of surface tension, we establish well-posedness in Sobolev spaces for the classical Stefan problem. We introduce a new velocity variable which extends the velocity of the moving free-boundary into the interior domain. The equation satisfied by this velocity is used for the analysis in place of the heat equation satisfied by the temperature. Solutions to the classical Stefan problem are then constructed as the limit of solutions to a carefully chosen sequence of approximations to the velocity equation, in which the moving free-boundary is regularized and the boundary condition is modified in a such a way as to preserve the basic nonlinear structure of the original problem. With our methodology, we simultaneously find the required stability condition for well-posedness and obtain new estimates for the regularity of the moving free-boundary. Finally, we prove that solutions of the Stefan problem with positive surface tension {σ} converge to solutions of the classical Stefan problem as {σ to 0}.

  1. On the modelling of semi-insulating GaAs including surface tension and bulk stresses

    Energy Technology Data Exchange (ETDEWEB)

    Dreyer, W.; Duderstadt, F.

    2004-07-01

    Necessary heat treatment of single crystal semi-insulating Gallium Arsenide (GaAs), which is deployed in micro- and opto- electronic devices, generate undesirable liquid precipitates in the solid phase. The appearance of precipitates is influenced by surface tension at the liquid/solid interface and deviatoric stresses in the solid. The central quantity for the description of the various aspects of phase transitions is the chemical potential, which can be additively decomposed into a chemical and a mechanical part. In particular the calculation of the mechanical part of the chemical potential is of crucial importance. We determine the chemical potential in the framework of the St. Venant-Kirchhoff law which gives an appropriate stress/strain relation for many solids in the small strain regime. We establish criteria, which allow the correct replacement of the St. Venant-Kirchhoff law by the simpler Hooke law. The main objectives of this study are: (i) We develop a thermo-mechanical model that describes diffusion and interface motion, which both are strongly influenced by surface tension effects and deviatoric stresses. (ii) We give an overview and outlook on problems that can be posed and solved within the framework of the model. (iii) We calculate non-standard phase diagrams, i.e. those that take into account surface tension and non-deviatoric stresses, for GaAs above 786 C, and we compare the results with classical phase diagrams without these phenomena. (orig.)

  2. Curvature-dependence of the liquid-vapor surface tension beyond the Tolman approximation

    CERN Document Server

    Bruot, Nicolas

    2016-01-01

    Surface tension is a macroscopic manifestation of the cohesion of matter, and its value $\\sigma_\\infty$ is readily measured for a flat liquid-vapor interface. For interfaces with a small radius of curvature $R$, the surface tension might differ from $\\sigma_\\infty$. The Tolman equation, $\\sigma(R) = \\sigma_\\infty / (1 + 2 \\delta/R)$, with $\\delta$ a constant length, is commonly used to describe nanoscale phenomena such as nucleation. Here we report experiments on nucleation of bubbles in ethanol and n-heptane, and their analysis in combination with their counterparts for the nucleation of droplets in supersaturated vapors, and with water data. We show that neither a constant surface tension nor the Tolman equation can consistently describe the data. We also investigate a model including $1/R$ and $1/R^2$ terms in $\\sigma(R)$. We describe a general procedure to obtain the coefficients of these terms from detailed nucleation experiments. This work explains the conflicting values obtained for the Tolman length i...

  3. Two Surface-Tension Formulations For The Level Set Interface-Tracking Method

    Energy Technology Data Exchange (ETDEWEB)

    Shepel, S.V.; Smith, B.L

    2005-03-01

    The paper describes a comparative study of two surface-tension models for the Level Set interface tracking method. In both models, the surface tension is represented as a body force, concentrated near the interface, but the technical implementation of the two options is different. The first is based on a traditional Level Set approach, in which the surface tension is distributed over a narrow band around the interface using a smoothed Delta function. In the second model, which is based on the integral form of the fluid-flow equations, the force is imposed only in those computational cells through which the interface passes. Both models have been incorporated into the Finite-Element/Finite-Volume Level Set method, previously implemented into the commercial Computational Fluid Dynamics (CFD) code CFX-4. A critical evaluation of the two models, undertaken in the context of four standard Level Set benchmark problems, shows that the first model, based on the smoothed Delta function approach, is the more general, and more robust, of the two. (author)

  4. The roles of wettability and surface tension in droplet formation during inkjet printing.

    Science.gov (United States)

    He, Bing; Yang, Sucui; Qin, Zhangrong; Wen, Binghai; Zhang, Chaoying

    2017-09-19

    This paper describes a lattice Boltzmann-based binary fluid model for inkjet printing. In this model, a time-dependent driving force is applied to actuate the droplet ejection. As a result, the actuation can be accurately controlled by adjusting the intensity and duration of the positive and negative forces, as well as the idle time. The present model was verified by reproducing the actual single droplet ejection process captured by fast imaging. This model was subsequently used to investigate droplet formation in piezoelectric inkjet printing. It was determined that the wettability of the nozzle inner wall and the surface tension of the ink are vital factors controlling the print quality and speed. Increasing the contact angle of the nozzle inner delays the droplet breakup time and reduces the droplet velocity. In contrast, higher surface tension values promote earlier droplet breakup and faster drop velocity. These results indicate that the hydrophilic modification of the nozzle inner wall and the choice of inks with high surface tensions will improve printing quality.

  5. Surface Tension and Lamellar Spacing in Polyelectrolyte Blends and Block Copolymers

    Science.gov (United States)

    Sing, Charles; Olvera de La Cruz, Monica

    2015-03-01

    Heterogeneous polymer systems such as block copolymers (BCPs) are governed primarily by a competition between the surface tension between different chemical species and the entropic stretching of the polymer chains. Charged BCPs represent a class of materials that is currently of great interest to the polymer community due to the promise of charged BCPs as nanostructured membranes for batteries and fuel cells. The inclusion of charge presents a powerful way to tune the structure of BCPs, and we develop our understanding of how to do so by investigating the interfacial properties (surface tension and microstructure size) of polyelectrolyte blends and block copolymers. We use a new method that combines the features of liquid state (LS) theory and self consistent field theory (SCFT) into a multiscale LS-SCFT theory that provides beyond-mean-field predictions of polyelectrolyte systems. We find that charge size, charge correlations, and the fraction of charged monomers plays a crucial role in determining surface tension, and we therefore demonstrate how BCP structure changes upon inclusion of charges. Finally, we will show that these predictions provide the ideal basis for comparison to experiment and subsequent refinement of LS-SCFT theory.

  6. The interfacial surface tension of a quark-gluon plasma fireball in a hadronic medium

    Indian Academy of Sciences (India)

    R Ramanathan; K K Gupta; Agam K Jha; S S Singh

    2007-05-01

    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 model calculation of surface tension. The velocity of sound in the QGP droplet is predicted to be in the range (0.27 ± 0.02) times the velocity of light in vacuum and this value is independent of both the value of the transition temperature and the model parameters.

  7. Surface Tension and Negative Pressure Interior of a Non-Singular `Black Hole'

    CERN Document Server

    Mazur, Pawel O

    2015-01-01

    The constant density interior Schwarzschild solution for a static, spherically symmetric collapsed star has a divergent pressure when its radius $R\\le\\frac{9}{8}R_s=\\frac{9}{4}GM$. We show that this divergence is integrable, and induces a non-isotropic transverse stress with a finite redshifted surface tension on a spherical surface of radius $R_0=3R\\sqrt{1-\\frac{8}{9}\\frac{R}{R_s}}$. For $r < R_0$ the interior Schwarzschild solution exhibits negative pressure. When $R=R_s$, the surface is localized at the Schwarzschild radius itself, $R_0=R_s$, and the solution has constant negative pressure $p =-\\bar\\rho$ everywhere in the interior $rsurface tension of the condensate star surface is given by $\\tau_s=\\Delta\\kappa/8\\pi G$, where $\\Delta\\kappa=\\kappa_+-\\kappa_-=2\\kappa_+=1/R_s$ is the difference of equal and opposite surface grav...

  8. The anisotropy of the surface tension at the magnetic-field-induced phase transformations

    CERN Document Server

    Cebers, A

    2002-01-01

    The surface properties of the magnetic colloid phases arising at the magnetic-field-induced phase separation in the Hele-Shaw cell are considered. By the numerical resolution of the equation for the concentration distribution in the transition layer between the phases, the anisotropy of the surface tension is calculated. The anisotropic shapes of the droplets of the concentrated phase are found by the Wulff construction and are compared with that obtained by the numerical simulation of the kinetics of the magnetic colloid phase separation in the Hele-Shaw cell.

  9. 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

  10. Effects of Ce concentrations on ignition temperature and surface tension of Mg-9wt.%Al alloy

    Directory of Open Access Journals (Sweden)

    Deng Zhenghua

    2013-03-01

    Full Text Available Magnesium alloys are well known for their excellent properties, but the potential issues with oxidation and burning during melting and casting largely limit its industrial applications. The addition of Ce in magnesium alloys can significantly raise ignition-proof performance and change the structure of the oxide film on the surface of the molten metal as well as the surface tension values. Surface tension is an important physical parameter of the metal melts, and it plays an important role in the formation of surface oxide film. In this present work, the ignition temperature and the surface tension of Mg-9wt.%Al alloy with different Ce concentrations were studied. Surface tensions was measured using the maximum bubble pressure method (MBPM. Ignition temperature was measured using NiCr-NiSi type thermocouples and was monitored and recorded via a WXT-604 desk recording device. The results show that the ignition point of Mg-9wt.%Al alloy can be effectively elevated by adding Ce. The ignition temperature reaches its highest point of 720 ℃ when the addition of Ce is 1wt.%. The surface tension of the molten Mg-9wt.%Al alloy decreases exponentially with the increase of Ce addition at the same temperature. Similarly, the experiment also shows that the surface tension of Mg-9wt.%Al alloy decreases exponentially with the increase of temperature.

  11. Reactive processing of formaldehyde and acetaldehyde in aqueous aerosol mimics: surface tension depression and secondary organic products

    Directory of Open Access Journals (Sweden)

    Z. Li

    2011-11-01

    Full Text Available The reactive uptake of carbonyl-containing volatile organic compounds (cVOCs by aqueous atmospheric aerosols is a likely source of particulate organic material. The aqueous-phase secondary organic products of some cVOCs are surface-active. Therefore, cVOC uptake can lead to organic film formation at the gas-aerosol interface and changes in aerosol surface tension. We examined the chemical reactions of two abundant cVOCs, formaldehyde and acetaldehyde, in water and aqueous ammonium sulfate (AS solutions mimicking tropospheric aerosols. Secondary organic products were identified using Aerosol Chemical Ionization Mass Spectrometry (Aerosol-CIMS, and changes in surface tension were monitored using pendant drop tensiometry. Hemiacetal oligomers and aldol condensation products were identified using Aerosol-CIMS. Acetaldehyde depresses surface tension to 65(±2 dyn cm−1 in pure water (a 10% surface tension reduction from that of pure water and 62(±1 dyn cm−1 in AS solutions (a 20.6% reduction from that of a 3.1 M AS solution. Surface tension depression by formaldehyde in pure water is negligible; in AS solutions, a 9% reduction in surface tension is observed. Mixtures of these species were also studied in combination with methylglyoxal in order to evaluate the influence of cross-reactions on surface tension depression and product formation in these systems. We find that surface tension depression in the solutions containing mixed cVOCs exceeds that predicted by an additive model based on the single-species isotherms.

  12. Model HULIS compounds in nanoaerosol clusters - investigations of surface tension and aggregate formation using molecular dynamics simulations

    National Research Council Canada - National Science Library

    T. Hede; X. Li; C. Leck; Y. Tu; H. Ågren

    2011-01-01

    .... In this study we use molecular dynamics simulations to show that model humic-like substances (HULIS) in systems containing 10 000 water molecules mimic experimental data well referring to reduction of surface tension...

  13. Surface tension of a coal extract in an organic solvent; Sekitan chushutsu seibun no kaigo to hyomen choryoku

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, T.; Hayasaka, K.; Takanohashi, T.; Iino, M. [Tohoku University, Sendai (Japan). Institute for Chemical Reaction Science

    1996-10-28

    The behavior and properties of associated bodies were studied through measurement of surface tension considering acetone-soluble fraction relatively light among various solvent extracts of coal. In experiment, the acetone-soluble fraction was extracted from the substances extracted from Upper Freeport coal as standard specimen using the mixed solvent of carbon disulfide (CS2) and N-methyl-2-pyrrolidinone (NMP), and it was dissolved into NMP after drying. Surface tension was measured by Wilhelmy method. The experimental results are as follows. Equilibrium surface tension is equal to the surface tension of pure solvent in a low concentration range of solution, and decreases with an increase in concentration approaching a fixed value at 0 in log concentration, nearly showing an S curve. Adsorption of species with non-polar aromatic ring of the acetone-soluble fraction on a solution surface probably decreases surface tension. Change with time in surface tension is observed which suggests fast initial reaction and slow subsequent reaction. 4 figs.

  14. Effect of surface modification on interfacial nanobubble morphology and contact line tension.

    Science.gov (United States)

    Rangharajan, Kaushik K; Kwak, Kwang J; Conlisk, A T; Wu, Yan; Prakash, Shaurya

    2015-07-14

    Past research has confirmed the existence of surface nanobubbles on various hydrophobic substrates (static contact angle >90°) when imaged in air-equilibrated water. Additionally, the use of solvent exchange techniques (based on the difference in saturation levels of air in various solvents) also introduced surface nanobubbles on hydrophilic substrates (static contact angle static contact angle of 81.1°), bromo-terminated silica (BTS; static contact angle of 85.5°), and fluoro-terminated silica (FTS; static contact angle of 105.3°) surfaces when immersed in air-equilibrated water without solvent exchange. Nanobubbles formed on the above three substrates were characterized on the basis of Laplace pressure, bubble density, and contact line tension. Results reported here show that (1) the Laplace pressures of all nanobubbles formed on both BTS and polycarbonate were an order of magnitude higher than those of FTS, (2) the nanobubble number density per unit area decreased with an increase in substrate contact angle, and (3) the contact line tension of the nanobubbles was calculated to be positive for both BTS and polycarbonate (lateral radius, Rs 50 nm for all nanobubbles). The nanobubble morphology and distribution before and after using the solvent exchange method (ethanol-water), on the bulk polycarbonate substrate was also characterized. Analysis for these polycarbonate surface nanobubbles showed that both the Laplace pressure and nanobubble density reduced by ≈98% after ethanol-water exchange, accompanied by a flip in the magnitude of contact line tension from positive (0.19 nN) to negative (-0.11 nN).

  15. Online measurements of surface tensions and viscosities based on the hydrodynamics of Taylor flow in a microchannel

    Science.gov (United States)

    Sun, Yanhong; Guo, Chaohong; Jiang, Yuyan; Wang, Tao; Zhang, Lei

    2016-11-01

    This paper demonstrates an online measurement technique which can measure both surface tension and viscosity for confined fluids in microfluidic systems. The surface tension and viscosity are determined by monitoring the liquid film thickness deposited in a microchannel based on the hydrodynamics of Taylor flow. Measurements were carried out for pure liquids and binary aqueous liquid mixtures. The results agreed well with reference data and theoretical models. This novel method has considerable potential for measuring dynamic interfacial tension of complex mixtures. Furthermore, it offers opportunity for integrating property measurement with two-phase flow in microchannel, opening new lines of applications.

  16. Simultaneous measurement of contact angle and surface tension using axisymmetric drop-shape analysis-no apex (ADSA-NA).

    Science.gov (United States)

    Kalantarian, A; David, R; Chen, J; Neumann, A W

    2011-04-05

    Axisymmetric drop-shape analysis-no apex (ADSA-NA) is a recent drop-shape method that allows the simultaneous measurement of contact angles and surface tensions of drop configurations without an apex (i.e., a sessile drop with a capillary protruding into the drop). Although ADSA-NA significantly enhanced the accuracy of contact angle and surface tension measurements compared to that of original ADSA using a drop with an apex, it is still not as accurate as a surface tension measurement using a pendant drop suspended from a holder. In this article, the computational and experimental aspects of ADSA-NA were scrutinized to improve the accuracy of the simultaneous measurement of surface tensions and contact angles. It was found that the results are relatively insensitive to different optimization methods and edge detectors. The precision of contact angle measurement was enhanced by improving the location of the contact points of the liquid meniscus with the solid substrate to subpixel resolution. To optimize the experimental design, the capillary was replaced with an inverted sharp-edged pedestal, or holder, to control the drop height and to ensure the axisymmetry of the drops. It was shown that the drop height is the most important experimental parameter affecting the accuracy of the surface tension measurement, and larger drop heights yield lower surface tension errors. It is suggested that a minimum nondimensional drop height (drop height divided by capillary length) of 1.7 is required to reach an error of less than 0.2 mJ/m(2) for the measured surface tension. As an example, the surface tension of water was measured to be 72.46 ± 0.04 at 24 °C by ADSA-NA, compared to 72.39 ± 0.01 mJ/m(2) obtained with pendant drop experiments.

  17. Heat Transfer in a Liquid-Solid Circulating Fluidized Bed Reactor with Low Surface Tension Media

    Institute of Scientific and Technical Information of China (English)

    HR Jin; H Lim; DH Lim; Y Kang; Ki-Won Jun

    2013-01-01

    Heat transfer characteristics between the immersed heater and the bed content were studied in the riser of a liquid-solid circulating fluidized bed, whose diameter and height were 0.102 m (ID) and 2.5 m, respectively. Effects of liquid velocity, particle size, surface tension of liquid phase and solid circulation rate on the overall heat transfer coefficient were examined. The heat transfer coefficient increased with increasing particle size or solid cir-culation rate due to the higher potential of particles to contact with the heater surface and promote turbulence near the heater surface. The value of heat transfer coefficient increased gradually with increase in the surface tension of liquid phase, due to the slight increase of solid holdup. The heat transfer coefficient increased with the liquid veloc-ity even in the higher range, due to the solid circulation prevented the decrease in solid holdup, in contrast to that in the conventional liquid-solid fluidized beds. The values of heat transfer coefficient were well correlated in terms of dimensionless groups as well as operating variables.

  18. Some remarks on the solid surface tension determination from contact angle measurements

    Science.gov (United States)

    Zdziennicka, Anna; Szymczyk, Katarzyna; Krawczyk, Joanna; Jańczuk, Bronisław

    2017-05-01

    The measurements of water, formamide and diiodomethane contact angle (θ) on polytetrafluoroethylene (PTFE), polyethylene (PE), polymethyl methacrylate (PMMA), nylon 6, quartz and silica were performed. Based on the θ values of these liquids obtained on PTFE, the Lifshitz-van der Waals and acid-base and/or dispersion and polar components of their surface tension (ST) were determined. In turn, the θ values for water, formamide and diiodomethane on PMMA were applied to calculate the electron-acceptor and electron-donor parameters of the Lewis acid-base component of the formamide ST. For this calculation the same values of the electron-acceptor and electron-donor parameters for water ST were used. Taking into account the values of components and parameters of water, formamide and diiodomethane ST obtained by us, van Oss et al. and from the water(formamide)-n-alkane and water-diiodomethane interface tension, the components and parameters of studied solids ST were calculated. To this end different approaches to the interface tension were considered. The obtained values were compared with those in the literature. It was concluded that for determination of solid ST components and parameters, those of water, formamide and diiodomethane ST obtained from the θ measurements on the model solids should be used.

  19. Short-Time Structural Stability of Compressible Vortex Sheets with Surface Tension

    Science.gov (United States)

    Stevens, Ben

    2016-11-01

    Assume we start with an initial vortex-sheet configuration which consists of two inviscid fluids with density bounded below flowing smoothly past each other, where a strictly positive fixed coefficient of surface tension produces a surface tension force across the common interface, balanced by the pressure jump. We model the fluids by the compressible Euler equations in three space dimensions with a very general equation of state relating the pressure, entropy and density such that the sound speed is positive. We prove that, for a short time, there exists a unique solution of the equations with the same structure. The mathematical approach consists of introducing a carefully chosen artificial viscosity-type regularisation which allows one to linearise the system so as to obtain a collection of transport equations for the entropy, pressure and curl together with a parabolic-type equation for the velocity which becomes fairly standard after rotating the velocity according to the interface normal. We prove a high order energy estimate for the non-linear equations that is independent of the artificial viscosity parameter which allows us to send it to zero. This approach loosely follows that introduced by Shkoller et al. in the setting of a compressible liquid-vacuum interface. Although already considered by Coutand et al. [10] and Lindblad [17], we also make some brief comments on the case of a compressible liquid-vacuum interface, which is obtained from the vortex sheets problem by replacing one of the fluids by vacuum, where it is possible to obtain a structural stability result even without surface tension.

  20. Effect of increased surface tension and assisted ventilation on /sup 99m/Tc-DTPA clearance

    Energy Technology Data Exchange (ETDEWEB)

    Jefferies, A.L.; Kawano, T.; Mori, S.; Burger, R.

    1988-02-01

    Experiments were performed to determine the effects of conventional mechanical ventilation (CMV) and high-frequency oscillation (HFO) on the clearance of technetium-99m-labeled diethylenetriamine pentaacetate (/sup 99m/Tc-DTPA) from lungs with altered surface tension properties. A submicronic aerosol of /sup 99m/Tc-DTPA was insufflated into the lungs of anesthetized, tracheotomized rabbits before and 1 h after the administration of the aerosolized detergent dioctyl sodium sulfosuccinate (OT). Rabbits were ventilated by one of four methods: 1) spontaneous breathing; 2) CMV at 12 cmH2O mean airway pressure (MAP); 3) HFO at 12 cmH2O MAP; 4) HFO at 16 cmH2O MAP. Administration of OT resulted in decreased arterial PO2 (PaO2), increased lung wet-to-dry weight ratios, and abnormal lung pressure-volume relationships, compatible with increased surface tension. /sup 99m/Tc-DTPA clearance was accelerated after OT in all groups. The post-OT rate of clearance (k) was significantly faster (P less than 0.05) in the CMV at 12 cmH2O MAP (k = 7.57 +/- 0.71%/min (SE)) and HFO at 16 cmH2O MAP (k = 6.92 +/- 0.61%/min) groups than in the spontaneously breathing (k = 4.32 +/- 0.55%/min) and HFO at 12 cmH2O MAP (4.68 +/- 0.63%/min) groups. The clearance curves were biexponential in the former two groups. We conclude that pulmonary clearance of /sup 99m/Tc-DTPA is accelerated in high surface tension pulmonary edema, and this effect is enhanced by both conventional ventilation and HFO at high mean airway pressure.

  1. Measurement and Modeling of Surface Tensions of Asymmetric Systems: Heptane, Eicosane, Docosane, Tetracosane and their Mixtures

    DEFF Research Database (Denmark)

    Queimada, Antonio; Silva, Filipa A. E.; Caco, Ana I.;

    2003-01-01

    To extend the surface tension database for heavy or asymmetric n-alkane mixtures, measurements were performed using the Wilhelmy plate method. Measured systems included the binary mixtures heptane + eicosane, heptane + docosane and heptane + tetracosane and the ternary mixture heptane + eicosane...... was assessed. It is shown that using a new generalized combining rule for the critical temperature, the data can be described with deviations of about 1% that is within the experimental uncertainty of the measurements. (C) 2003 Elsevier B.V. All rights reserved....

  2. A new experimental method for determining liquid density and surface tension

    Science.gov (United States)

    Chou, Kjo-Chih; Hu, Jian-Hong

    1991-02-01

    A summary concerning the measurement of liquid density relying on the Archimedes principle has been presented, based on which a new effective method with a specially designed bob for determining liquid density has been suggested. The application of this method to ethyl alcohol solution and liquid glycerol, as well as a theoretical error analysis, shows that this new method is significant, because not only can it simplify the procedure of measurement but it can also offer more precise results. Besides, this method can further provide surface tension or contact angle simultaneously. It is expected that this new method will find its application in hightemperature melts.

  3. The Dynamic Role of Melt-Vapor Surface Tension in Magmatic Degassing

    Science.gov (United States)

    Mangan, M.; Sisson, T.

    2004-05-01

    It is well known from classical nucleation theory that melt-vapor surface tension (σ ) critically influences both the supersaturation pressure needed to initiate eruptive degassing (Δ Pcritical) and the rate of gas bubble nucleation (J ). Here we highlight an important aspect of melt-vapor surface tension that is generally ignored, namely, that σ is dynamic quantity responsive to the changes in melt composition, water content, and temperature that occur during magma storage and ascent. Crystallization, degassing, and cooling impart a time-dependency to σ that must be considered in any effort to accurately model eruption processes. In this study, we document changes to σ in natural, water-saturated dacitic melt at 200 MPa and 950-1055° C and 5.7-4.8 wt% H2O. Rather than traditional macroscopic measurements (sessile drop, capillarity, detachment techniques), we experimentally determine the Δ Pcritical of bubble nucleation during depressurization from 200 MPa as a function of T and wt% H2O (techniques as in Mangan and Sisson, E&PSL, 2000), and then solve for σ at those conditions using classical nucleation theory (Blander and Katz, AIChE Jour., 1975). Meshing experiment and theory gives σ = 42 (±3), 60 (±7), 73 (±3) mN/m at T= 950, 1000, 1055° C, and H2O = 5.7 (±0.1), 5.3 (±0.2), 4.8 (±0.1) wt%, respectively. Our data show a negative dependence of σ on dissolved water content of -33 mN/m/wt% H2O and a positive dependence of σ on temperature of +0.30 mN/m/° C. Comparable relationships between σ and changing water content and temperature were obtained in sessile-drop style experiments using hydrous haplogranite melts (Bagdassarov et al., Amer. Mineral., 2000). To illustrate how the observed σ -H2O-T dependencies might impact degassing models we consider two idealized regimes. The first is a storage regime in which isobaric cooling and crystallization in the magma chamber gradually increases the H2O content of the residual melt. Surface tension is

  4. Effects of surface tension and electrochemical reactions in Li-ion battery electrode nanoparticles

    Science.gov (United States)

    Stein, Peter; Zhao, Ying; Xu, Bai-Xiang

    2016-11-01

    The size- and shape-dependency of the chemo-mechanical behavior of spherical and ellipsoidal nanoparticles in Li-ion battery electrodes are investigated by a stress-assisted diffusion model and 3D finite element simulations. The model features surface tension, a direct coupling between diffusion and elasticity, concentration-dependent diffusivity, and a Butler-Volmer relation for the description of electrochemical reactions that is modified to account for mechanical effects. Simulation results on spherical particles reveal that surface tension causes additional pressure fields in the particles, shifting the stress state towards the compressive regime. This provides mechanical stabilization, allowing, in principle, for higher charge/discharge rates. However, due to this pressure the attainable lithiation for a given potential difference is reduced during insertion, whereas a higher amount of ions is given off during extraction. Ellipsoidal particles with an aspect ratio deviating from that of a sphere with the same volume expose a larger surface area to the intercalation reactions. Consequently, they exhibit accelerated (dis)charge rates. However, due to the enhanced pressure in regions with high curvature, the accessible capacity of ellipsoidal particles is less than that of spherical particles.

  5. Surface tension effects on the onset of double-diffusive convection

    Science.gov (United States)

    Chen, C. F.

    Experiments have been carried out to determine the critical thermal Rayleigh number for onset of convection in a horizontal layer of density-stratified fluid with a free surface when heated from below. Three different aqueous solutions were used: salt, glycerol, and acetic acid. The rates of change in surface tension with concentration for these three solutions are positive, nearly zero, and negative, respectively. Compared to the rigid-rigid boundaries, the critical thermal Rayleigh number was found to be larger by 11.2 percent for the salt solution and smaller by 10.0 percent for the glycerol solution. With the acetic acid solution, however, the effect of the free surface was found to be negligible.

  6. Surface tension, viscosity, and rheology of water-based nanofluids: a microscopic interpretation on the molecular level

    Science.gov (United States)

    Lu, Gui; Duan, Yuan-Yuan; Wang, Xiao-Dong

    2014-09-01

    Nanofluids are suspensions of nanometer-sized particles which significantly modify the properties of the base fluids. Nanofluids exhibit attractive properties, such as high thermal conductivity, tunable surface tension, viscosity, and rheology. Various attempts have been made to understand the mechanisms for these property modifications caused by adding nanoparticles; however, due to the lack of direct nanoscale evidence, these explanations are still controversial. This work calculated the surface tension, viscosity, and rheology of gold-water nanofluids using molecular dynamics simulations which provide a microscopic interpretation for the modified properties on the molecular level. The gold-water interaction potential parameters were changed to mimic various nanoparticle types. The results show that the nanoparticle wettability is responsible for the modified surface tension. Hydrophobic nanoparticles always tend to stay on the free surface so they behave like a surfactant to reduce the surface tension. Hydrophilic nanoparticles immersed into the bulk fluid impose strong attractive forces on the water molecules at the free surface which reduces the free surface thickness and increases the surface tension of the nanofluid. Solid-like absorbed water layers were observed around the nanoparticles which increase the equivalent nanoparticle radius and reduce the mobility of the nanoparticles within the base fluid which increases the nanofluid viscosity. The results show the water molecule solidification between two or many nanoparticles at high nanoparticle loadings, but the solidification effect is suppressed for shear rates greater than a critical shear rate; thus Newtonian nanofluids can present shear-thinning non-Newtonian behavior.

  7. Empirical correlation of the surface tension versus the viscosity for saturated normal liquids

    CERN Document Server

    Li, Xia; Mulero, A

    2016-01-01

    In 1966 Pelofsky proposed an empirical linear correlation between the natural logarithm of the surface tension and the reciprocal viscosity, which seems to work adequately for a wide range of fluids. In particular, it has been shown that it is useful in the case of n-alkanes and their binary and ternary mixtures. More recently however, it has been found not to work for several ionic liquids unless the reciprocal viscosity is raised to a power. The exponent of this power was fixed to be 0.3, at least for the studied ionic fluids. In the present work, the performance and accuracy of both the original Pelofsky correlation and the modified expression including the exponent are studied for 56 non-ionic fluids of different kinds over a broad range of temperatures. Also, the temperature range is delimited for which each expression reproduces the surface tension values with average absolute deviations below 1%. The needed coefficients are given for both the broad and the delimited temperature range for each expressio...

  8. A sharp interface method for compressible liquid–vapor flow with phase transition and surface tension

    Energy Technology Data Exchange (ETDEWEB)

    Fechter, Stefan, E-mail: stefan.fechter@iag.uni-stuttgart.de [Institut für Aerodynamik und Gasdynamik, Universität Stuttgart, Pfaffenwaldring 21, 70569 Stuttgart (Germany); Munz, Claus-Dieter, E-mail: munz@iag.uni-stuttgart.de [Institut für Aerodynamik und Gasdynamik, Universität Stuttgart, Pfaffenwaldring 21, 70569 Stuttgart (Germany); Rohde, Christian, E-mail: Christian.Rohde@mathematik.uni-stuttgart.de [Institut für Angewandte Analysis und Numerische Simulation, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart (Germany); Zeiler, Christoph, E-mail: Christoph.Zeiler@mathematik.uni-stuttgart.de [Institut für Angewandte Analysis und Numerische Simulation, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart (Germany)

    2017-05-01

    The numerical approximation of non-isothermal liquid–vapor flow within the compressible regime is a difficult task because complex physical effects at the phase interfaces can govern the global flow behavior. We present a sharp interface approach which treats the interface as a shock-wave like discontinuity. Any mixing of fluid phases is avoided by using the flow solver in the bulk regions only, and a ghost-fluid approach close to the interface. The coupling states for the numerical solution in the bulk regions are determined by the solution of local two-phase Riemann problems across the interface. The Riemann solution accounts for the relevant physics by enforcing appropriate jump conditions at the phase boundary. A wide variety of interface effects can be handled in a thermodynamically consistent way. This includes surface tension or mass/energy transfer by phase transition. Moreover, the local normal speed of the interface, which is needed to calculate the time evolution of the interface, is given by the Riemann solution. The interface tracking itself is based on a level-set method. The focus in this paper is the description of the two-phase Riemann solver and its usage within the sharp interface approach. One-dimensional problems are selected to validate the approach. Finally, the three-dimensional simulation of a wobbling droplet and a shock droplet interaction in two dimensions are shown. In both problems phase transition and surface tension determine the global bulk behavior.

  9. A sharp interface method for compressible liquid-vapor flow with phase transition and surface tension

    Science.gov (United States)

    Fechter, Stefan; Munz, Claus-Dieter; Rohde, Christian; Zeiler, Christoph

    2017-05-01

    The numerical approximation of non-isothermal liquid-vapor flow within the compressible regime is a difficult task because complex physical effects at the phase interfaces can govern the global flow behavior. We present a sharp interface approach which treats the interface as a shock-wave like discontinuity. Any mixing of fluid phases is avoided by using the flow solver in the bulk regions only, and a ghost-fluid approach close to the interface. The coupling states for the numerical solution in the bulk regions are determined by the solution of local two-phase Riemann problems across the interface. The Riemann solution accounts for the relevant physics by enforcing appropriate jump conditions at the phase boundary. A wide variety of interface effects can be handled in a thermodynamically consistent way. This includes surface tension or mass/energy transfer by phase transition. Moreover, the local normal speed of the interface, which is needed to calculate the time evolution of the interface, is given by the Riemann solution. The interface tracking itself is based on a level-set method. The focus in this paper is the description of the two-phase Riemann solver and its usage within the sharp interface approach. One-dimensional problems are selected to validate the approach. Finally, the three-dimensional simulation of a wobbling droplet and a shock droplet interaction in two dimensions are shown. In both problems phase transition and surface tension determine the global bulk behavior.

  10. Quantum Magnetic Oscillations of the Surface Tension at a Metal-Insulator Interface

    Science.gov (United States)

    Dubovskii, L. B.

    2016-03-01

    Any metal-insulator transition (MI transition) in a crystalline material must be a transition from a situation in which electronic bands overlap to a situation when they do not (Mott, Metal-insulator, 2nd edn. Taylor@Francis, London, 1990). For this case the self-consistent equations for the two-band conductor are formulated (cf. Dubovskii, JETP Lett. 99(1):22-26, 2014). The description of the MI phase transition is based on two order parameters. The first one is the material density distribution at the MI boundary ρ ({vec {r}}). The second one is a four-component complex vector in spin space Upsilon ({vec {r}}). The value Upsilon ({vec {r}}) determines the electron density in the metallic or semimetallic phase in the presence of an external magnetic field. Two different components of the vector describe possible spin states of electrons and holes inserted in the external magnetic field. The solution gives a singular behavior of the surface tension at the MI interface in the vicinity of the MI phase transition. At low temperature quantum oscillations of the surface tension in the magnetic field take place.

  11. Conditions necessary for capillary hysteresis in porous media: Tests of grain size and surface tension influences

    Science.gov (United States)

    Tokunaga, Tetsu K.; Olson, Keith R.; Wan, Jiamin

    2004-05-01

    Hysteresis in the relation between water saturation and matric potential is generally regarded as a basic aspect of unsaturated porous media. However, the nature of an upper length scale limit for saturation hysteresis has not been previously addressed. Since hysteresis depends on whether or not capillary rise occurs at the grain scale, this criterion was used to predict required combinations of grain size, surface tension, fluid-fluid density differences, and acceleration in monodisperse systems. The Haines number (Ha), composed of the aforementioned variables, is proposed as a dimensionless number useful for separating hysteretic (Ha 15) behavior. Vanishing of hysteresis was predicted to occur for grain sizes greater than 10.4 ± 0.5 mm, for water-air systems under the acceleration of ordinary gravity, based on Miller-Miller scaling and Haines' original model for hysteresis. Disappearance of hysteresis was tested through measurements of drainage and wetting curves of sands and gravels and occurs between grain sizes of 10 and 14 mm (standard conditions). The influence of surface tension was tested through measurements of moisture retention in 7 mm gravel, without and with a surfactant (sodium dodecylbenzenesulfonate (SDBS)). The ordinary water system (Ha = 7) exhibited hysteresis, while the SDBS system (Ha = 18) did not. The experiments completed in this study indicate that hysteresis in moisture retention relations has an upper limit at Ha = 16 ± 2 and show that hysteresis is not a fundamental feature of unsaturated porous media.

  12. Thin Film Morphology of Block Copolymers Containing Polydimethylsiloxane as a Function of the Surface Tension of the Opposing Block

    Science.gov (United States)

    Wadley, Maurice; Cavicchi, Kevin

    2008-03-01

    The self-assembly of block copolymers into ordered nanostructures such as spheres, cylinders, and lamellae in the range of 10-100 nm makes them interesting materials for patterning surfaces. Thin films of block copolymers containing poly(dimethylsiloxane) (PDMS) are attractive for patterning due to their high oxygen etch resistance compared to other polymers. The main disadvantage of these polymers for patterning is the low surface tension of PDMS. This causes the preferential migration of PDMS to the air/film interface driving the formation of domains parallel to the interface and surface wetting layers. In this work a series of AB block copolymers containing PDMS have been prepared where the surface tension of the opposing block was varied. The effect of changing the surface tension mismatch between the blocks on the thin film morphology will be discussed.

  13. STUDIES ON SURFACE TENSION OF SELECTED MOUTHWASH FORMULATION BY DROP NUMBER METHOD USING TRAUBE’S STALAGMOMETER TECHNIQUE

    Directory of Open Access Journals (Sweden)

    Ghindora Ghanshayam L

    2011-02-01

    Full Text Available The selected marketed mouthwash formulations was carried out using Traube’s stalagmometer technique by drop number method to determine their individual surface tension for further identification, structure elucidation and chemical constituents. The formulation I (Potassium nitrate & sodium fluoride, formulation II (Chlorhexidine gluconate, formulation III (Thymol, eucalyptol and menthol were selected for the case study. These formulations were also evaluated to their same quantity mixture ratio with distilled water combination for estimation of different percent composition. The main aim and rationale of the study was to evaluate the surface tension of three selected formulations with distilled water. In individual surface tension study, it was noted that formulation II (48.29 dyne/cm showed highest value and formulation III (40.81 dyne/cm showed lowest value comparison between the three formulations under laboratory conditions. The 50% formulation mixture with distilled water showed minimum surface tension (49.20 dyne/cm and 90% formulation mixture with distilled water showed maximum surface tension (54.30 dyne/cm amongst other composition. In our present study, all the percent composition values were less than standard surface tension value. The 20% (50.31 dyne/cm, 70% (50.64 dyne/cm, 80% (50.26 dyne/cm and 30% (49.30 dyne/cm, 50% (49.20 dyne/cm and also 40% (51.73 dyne/cm, 60% (51.26 dyne/cm formulation mixture with distilled water showed approximately same surface tension values.

  14. Surface tension-induced high aspect-ratio PDMS micropillars with concave and convex lens tips

    KAUST Repository

    Li, Huawei

    2013-04-01

    This paper reports a novel method for the fabrication of 3-dimensional (3D) Polydimethylsiloxane (PDMS) micropillars with concave and convex lens tips in a one-step molding process, using a CO2 laser-machined Poly(methyl methacrylate) (PMMA) mold with through holes. The PDMS micropillars are 4 mm high and have an aspect ratio of 251. The micropillars are formed by capillary force drawing up PDMS into the through hole mold. The concave and convex lens tips of the PDMS cylindrical micropillars are induced by surface tension and are controllable by changing the surface wetting properties of the through holes in the PMMA mold. This technique eliminates the requirements of expensive and complicated facilities to prepare a 3D mold, and it provides a simple and rapid method to fabricate 3D PDMS micropillars with controllable dimensions and tip shapes. © 2013 IEEE.

  15. The electrical conductivity, density and surface tension of molten salts containing zirconium fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Katyshev, S F; Teslyuk, L M; Eltsova, N V [Urals State Technical University-UPI, 19 Mira Str., Ekaterinburg 620002 (Russian Federation)], E-mail: tnv@htf.ustu.ru, E-mail: ksf@mail.ustu.ru

    2008-02-15

    The temperature dependencies of specific electric conductivity, density and surface tension of molten LiF-KF-ZrF{sub 4} mixtures in a wide concentration range were investigated using relative capillary method and method of maximum pressure in a gas bubble. The obtained values of molar electric conductivity, molar volumes and excess thermodynamic functions of melt surface layer have noticeable deviations from those calculated for ideal mixtures. This phenomenon can be explained by some specific interaction between the components of studied ternary mixtures. Mixing the components in such melts is accompanied by a noticeable interaction with predominant formation of stable zirconium fluoride complex ions. The values of deviations depend on the ionic composition of the salt mixtures.

  16. d-α-tocopherol nanoemulsions: Size properties, rheological behavior, surface tension, osmolarity and cytotoxicity

    Directory of Open Access Journals (Sweden)

    M.C. Teixeira

    2017-02-01

    Full Text Available The aim of this study was the assessment of the physicochemical stability of d-α-tocopherol formulated in medium chain triglyceride nanoemulsions, stabilized with Tween®80 and Lipoid®S75 as surfactant and co-surfactant, respectively. d-α-tocopherol was selected as active ingredient because of its well-recognized interesting anti-oxidant properties (such as radical scavenger for food and pharmaceutical industries. A series of nanoemulsions of mean droplet size below 90 nm (polydispersity index < 0.15 have been produced by high-pressure homogenization, and their surface electrical charge (zeta potential, pH, surface tension, osmolarity, and rheological behavior, were characterized as a function of the d-α-tocopherol loading. In vitro studies in Caco-2 cell lines confirmed the safety profile of the developed nanoemulsions with percentage of cell viability above 90% for all formulations.

  17. Surface tension of molten Al-Si alloy at temperatures ranging from 92.3 to 112.3 K

    Institute of Scientific and Technical Information of China (English)

    DOU Lei; YUAN ZhangFu; LI JianQiang; LI Jing; WANG XiaoQiang

    2008-01-01

    The surface tension of molten AlSi20 alloy has been measured by using the sessile drop method at 923-1123 K under argon atmosphere in both heating-up and cooling processes. The result shows that the surface tension of this alloy decreases as long as temperature increases. The results of surface tension and contact angles in heating-up process have differences from those obtained in cooling process, because the metal microstructures have some changes at different temperatures based on the metal genetic theory. The surface tension of molten AISi20 alloy and that of molten pure aluminum have been compared as well, and the temperature coefficient of AlSi20 alloy is slightly lower than that of Al. The result has been analyzed by the linear scanning analysis with ESEM. The concentration of silicon in most region of the bulk is lower than that of the surface and the addition of Si to pure Al decreases the surface tension of molten pure Al.

  18. A free energy-based surface tension force model for simulation of multiphase flows by level-set method

    Science.gov (United States)

    Yuan, H. Z.; Chen, Z.; Shu, C.; Wang, Y.; Niu, X. D.; Shu, S.

    2017-09-01

    In this paper, a free energy-based surface tension force (FESF) model is presented for accurately resolving the surface tension force in numerical simulation of multiphase flows by the level set method. By using the analytical form of order parameter along the normal direction to the interface in the phase-field method and the free energy principle, FESF model offers an explicit and analytical formulation for the surface tension force. The only variable in this formulation is the normal distance to the interface, which can be substituted by the distance function solved by the level set method. On one hand, as compared to conventional continuum surface force (CSF) model in the level set method, FESF model introduces no regularized delta function, due to which it suffers less from numerical diffusions and performs better in mass conservation. On the other hand, as compared to the phase field surface tension force (PFSF) model, the evaluation of surface tension force in FESF model is based on an analytical approach rather than numerical approximations of spatial derivatives. Therefore, better numerical stability and higher accuracy can be expected. Various numerical examples are tested to validate the robustness of the proposed FESF model. It turns out that FESF model performs better than CSF model and PFSF model in terms of accuracy, stability, convergence speed and mass conservation. It is also shown in numerical tests that FESF model can effectively simulate problems with high density/viscosity ratio, high Reynolds number and severe topological interfacial changes.

  19. Surface Tension Directed Fluidic Self-Assembly of Semiconductor Chips across Length Scales and Material Boundaries

    Directory of Open Access Journals (Sweden)

    Shantonu Biswas

    2016-03-01

    Full Text Available This publication provides an overview and discusses some challenges of surface tension directed fluidic self-assembly of semiconductor chips which are transported in a liquid medium. The discussion is limited to surface tension directed self-assembly where the capture, alignment, and electrical connection process is driven by the surface free energy of molten solder bumps where the authors have made a contribution. The general context is to develop a massively parallel and scalable assembly process to overcome some of the limitations of current robotic pick and place and serial wire bonding concepts. The following parts will be discussed: (2 Single-step assembly of LED arrays containing a repetition of a single component type; (3 Multi-step assembly of more than one component type adding a sequence and geometrical shape confinement to the basic concept to build more complex structures; demonstrators contain (3.1 self-packaging surface mount devices, and (3.2 multi-chip assemblies with unique angular orientation. Subsequently, measures are discussed (4 to enable the assembly of microscopic chips (10 μm–1 mm; a different transport method is introduced; demonstrators include the assembly of photovoltaic modules containing microscopic silicon tiles. Finally, (5 the extension to enable large area assembly is presented; a first reel-to-reel assembly machine is realized; the machine is applied to the field of solid state lighting and the emerging field of stretchable electronics which requires the assembly and electrical connection of semiconductor devices over exceedingly large area substrates.

  20. Studies on surface tension effect for free surface flow around floating models; Futai mokei mawari no jiyu hyomenryu ni oyobosu hyomen choryoku no eikyo ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, K. [Yokohama National Univ., Yokohama (Japan). Faculty of Engineering; Akiba, H. [Toyo Construction Co. Ltd., Tokyo (Japan)

    1996-12-31

    The effect of surface tension on free surface flow around floating models is discussed experimentally and numerically. Three-dimensional free surface flow around vertical circular cylinders floating in a circulating water channel was visually observed, where a surface-active agent was added to water. The results are analyzed using Weber number. The numerical analysis was done for vertical cylinder and CY100 models using the Rankine source method. Weber number of at least around 120 is necessary to eliminate the effect of surface tension from free surface flow around the CY100 model. The numerical analysis for the cylinder model needs simulation with wavelength shorter than that of free surface wave used by the Rankine source method. The model for the resistance test should be at least around 7m long to eliminate the effect of surface tension at Froude number of 0.1 or higher. 15 refs., 12 figs., 2 tabs.

  1. Studies on surface tension effect for free surface flow around floating models; Futai mokei mawari no jiyu hyomenryu ni oyobosu hyomen choryoku no eikyo ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, K. [Yokohama National Univ., Yokohama (Japan). Faculty of Engineering; Akiba, H. [Toyo Construction Co. Ltd., Tokyo (Japan)

    1996-12-31

    The effect of surface tension on free surface flow around floating models is discussed experimentally and numerically. Three-dimensional free surface flow around vertical circular cylinders floating in a circulating water channel was visually observed, where a surface-active agent was added to water. The results are analyzed using Weber number. The numerical analysis was done for vertical cylinder and CY100 models using the Rankine source method. Weber number of at least around 120 is necessary to eliminate the effect of surface tension from free surface flow around the CY100 model. The numerical analysis for the cylinder model needs simulation with wavelength shorter than that of free surface wave used by the Rankine source method. The model for the resistance test should be at least around 7m long to eliminate the effect of surface tension at Froude number of 0.1 or higher. 15 refs., 12 figs., 2 tabs.

  2. Effects of Environmental Oxygen Content and Dissolved Oxygen on the Surface Tension and Viscosity of Liquid Nickel

    Science.gov (United States)

    SanSoucie, M. P.; Rogers, J. R.; Kumar, V.; Rodriguez, J.; Xiao, X.; Matson, D. M.

    2016-07-01

    The NASA Marshall Space Flight Center's electrostatic levitation (ESL) laboratory has recently added an oxygen partial pressure controller. This system allows the oxygen partial pressure within the vacuum chamber to be measured and controlled in the range from approximately 10^{-28} {to} 10^{-9} bar, while in a vacuum atmosphere. The oxygen control system installed in the ESL laboratory's main chamber consists of an oxygen sensor, oxygen pump, and a control unit. The sensor is a potentiometric device that determines the difference in oxygen activity in two gas compartments (inside the chamber and the air outside of the chamber) separated by an electrolyte. The pump utilizes coulometric titration to either add or remove oxygen. The system is controlled by a desktop control unit, which can also be accessed via a computer. The controller performs temperature control for the sensor and pump, has a PID-based current loop and a control algorithm. Oxygen partial pressure has been shown to play a significant role in the surface tension of liquid metals. Oxide films or dissolved oxygen may lead to significant changes in surface tension. The effects on surface tension and viscosity by oxygen partial pressure in the surrounding environment and the melt dissolved oxygen content will be evaluated, and the results will be presented. The surface tension and viscosity will be measured at several different oxygen partial pressures while the sample is undercooled. Surface tension and viscosity will be measured using the oscillating droplet method.

  3. Effects of polar cortical cytoskeleton and unbalanced cortical surface tension on intercellular bridge thinning during cytokinesis

    Institute of Scientific and Technical Information of China (English)

    Li Wang; Mei-Wen An; Xiao-Na Li; Fang Yang; Yang Liu

    2011-01-01

    To probe the contributions of polar cortical cytoskeleton and the surface tension of daughter cells to intercellular bridgethinning dynamics during cytokinesis,we applied cytochalasin D (CD) or colchicine (COLC) in a highly localized manner to polar regions of dividing normal rat kidney (NRK) cells.We observed cellular morphological changes and analyzed the intercellular bridge thinning trajectories of dividing cells with different polar cortical characteristics.Global blebbistatin (BS) application was used to obtain cells losing active contractile force groups.Our results show that locally released CD or colchicine at the polar region caused inhibition of cytokinesis before ingression.Similar treatment at phases after ingression allowed completion of cytokinesis but dramatically influenced the trajectories of intercellular bridge thinning.Disturbing single polar cortical actin induced transformation of the intercellular bridge thinning process,and polar cortical tension controlled deformation time of intercellular bridges.Our study provides a feasible framework to induce and analyze the effects of local changes in mechanical properties of cellular components on single cellular cytokinesis.

  4. 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.

  5. Performing chemical reactions in virtual capillary of surface tension-confined microfluidic devices

    Indian Academy of Sciences (India)

    Angshuman Nag; Biswa Ranjan Panda; Arun Chattopadhyay

    2005-10-01

    In this paper we report a new method of fabrication of surface tension-confined microfluidic devices on glass. We have also successfully carried out some well-known chemical reactions in these fluidic channels to demonstrate the usefulness of these wall-less microchannels. The confined flow path of liquid was achieved on the basis of extreme differences in hydrophobic and hydrophilic characters of the surface. The flow paths were fabricated by making parallel lines using permanent marker pen ink or other polymer on glass surfaces. Two mirror image patterned glass plates were then sandwiched one on top of the other, separated by a thin gap - created using a spacer. The aqueous liquid moves between the surfaces by capillary forces, confined to the hydrophilic areas without wetting the hydrophobic lines, achieving liquid confinement without physical side-walls. We have shown that the microfluidic devices designed in such a way can be very useful due to their simplicity and low fabrication cost. More importantly, we have also demonstrated that the minimum requirement of such a working device is a hydrophilic line surrounded by hydrophobic environment, two walls of which are constituted of air and the rest is made of a hydrophobic surface.

  6. Laplacian drop shapes and effect of random perturbations on accuracy of surface tension measurement for different drop constellations.

    Science.gov (United States)

    Saad, Sameh M I; Neumann, A Wilhelm

    2015-08-01

    Theoretical drop shapes are calculated for three drop constellations: pendant drops, constrained sessile drops, and unconstrained sessile drops. Based on total Gaussian curvature, shape parameter and critical shape parameter are discussed as a function of different drop sizes and surface tensions. The shape parameter is linked to physical parameters for every drop constellation. The as yet unavailable detailed dimensional analysis for the unconstrained sessile drop is presented. Results show that the unconstrained sessile drop shape depends on a dimensionless volume term and the contact angle. Random perturbations are introduced and the accuracy of surface tension measurement is assessed for precise and perturbed profiles of the three drop constellations. It is concluded that pendant drops are the best method for accurate surface tension measurement, followed by constrained sessile drops. The unconstrained sessile drops come last because they tend to be more spherical at low and moderate contact angles. Of course, unconstrained sessile drops are the only option if contact angles are to be measured.

  7. On Riemann Solvers and Kinetic Relations for Isothermal Two-Phase Flows with Surface Tension

    CERN Document Server

    Rohde, Christian

    2016-01-01

    We consider a sharp-interface approach for the inviscid isothermal dynamics of compressible two-phase flow, that accounts for phase transition and surface tension effects. To fix the mass exchange and entropy dissipation rate across the interface kinetic relations are frequently used. The complete uni-directional dynamics can then be understood by solving generalized two-phase Riemann problems. We present new well-posedness theorems for the Riemann problem and corresponding computable Riemann solvers, that cover quite general equations of state, metastable input data and curvature effects. The new Riemann solver is used to validate different kinetic relations on physically relevant problems including a comparison with experimental data. Riemann solvers are building blocks for many numerical schemes that are used to track interfaces in two-phase flow. It is shown that the new Riemann solver enables reliable and efficient computations for physical situations that could not be treated before.

  8. 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.

  9. Pairwise Force Smoothed Particle Hydrodynamics model for multiphase flow: Surface tension and contact line dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Tartakovsky, Alexandre M.; Panchenko, Alexander

    2016-01-01

    We present a novel formulation of the Pairwise Force Smoothed Particle Hydrodynamics Model (PF-SPH) and use it to simulate two- and three-phase flows in bounded domains. In the PF-SPH model, the Navier-Stokes equations are discretized with the Smoothed Particle Hydrodynamics (SPH) method and the Young-Laplace boundary condition at the fluid-fluid interface and the Young boundary condition at the fluid-fluid-solid interface are replaced with pairwise forces added into the Navier-Stokes equations. We derive a relationship between the parameters in the pairwise forces and the surface tension and static contact angle. Next, we demonstrate the accuracy of the model under static and dynamic conditions. Finally, to demonstrate the capabilities and robustness of the model we use it to simulate flow of three fluids in a porous material.

  10. New correlations between viscosity and surface tension for saturated normal fluids

    CERN Document Server

    Zheng, Mengmeng; Mulero, A

    2016-01-01

    New correlations between viscosity and surface tension are proposed and checked for saturated normal fluids. The proposed correlations contain three or four adjustable coefficients for every fluid. They were obtained by fitting 200 data points, ranging from the triple point to a point very near to the critical one. Forty substances were considered, including simple fluids (such as rare gases), simple hydrocarbons, refrigerants, and some other substances such as carbon dioxide and water. Two correlation models with three adjustable coefficients were checked, and the results showed that the one based on the modified Pelofsky expression gives the better overall results. A new 4-coefficient correlation is then proposed which clearly improves the results, giving the lowest overall deviations for 32 out of the 40 substances considered and absolute average deviations below 10% for all of them.

  11. A multiscale method for compressible liquid-vapor flow with surface tension*

    Directory of Open Access Journals (Sweden)

    Jaegle Felix

    2013-01-01

    Full Text Available Discontinuous Galerkin methods have become a powerful tool for approximating the solution of compressible flow problems. Their direct use for two-phase flow problems with phase transformation is not straightforward because this type of flows requires a detailed tracking of the phase front. We consider the fronts in this contribution as sharp interfaces and propose a novel multiscale approach. It combines an efficient high-order Discontinuous Galerkin solver for the computation in the bulk phases on the macro-scale with the use of a generalized Riemann solver on the micro-scale. The Riemann solver takes into account the effects of moderate surface tension via the curvature of the sharp interface as well as phase transformation. First numerical experiments in three space dimensions underline the overall performance of the method.

  12. Surface tension at the liquid-vapor interface of screened ionic mixtures

    Directory of Open Access Journals (Sweden)

    M.González-Melchor

    2004-01-01

    Full Text Available The liquid-vapor interface of binary mixtures of charged particles is studied using molecular dynamics (MD simulations. The interaction between particles is given by a short-range repulsive potential plus an attractive/repulsive Yukawa term, which models screened electrostatic interactions. To obtain the components of the pressure tensor two methods were used: a hybrid MD method which combines the hard sphere and continuous forces and a standard continuous MD method where the hard sphere was replaced by a soft interaction. We show that both models give essentially the same results. As the range of interaction decreases, the critical temperature and surface tension increase. The comparison with the restricted primitive model of ionic fluids is discussed.

  13. Improved Correlation for Viscosity from Surface Tension Data for Saturated Normal Fluids

    CERN Document Server

    Tian, Jianxiang

    2016-01-01

    Several correlations between viscosity and surface tension for saturated normal fluids have been proposed in the literature. Usually, they include three or four adjustable coefficients for every fluid and give generally good results. In this paper we propose a new and improved four-coefficient correlation which was obtained by fitting data ranging from the triple point to a point very near to the critical one. Fifty four substances were considered, including simple fluids (such as rare gases), simple hydrocarbons, refrigerants, and some other substances such as carbon dioxide, water or ethanol. The new correlation clearly improves the results obtained with those previously available since it gives absolute average deviations below1% for 40 substances and below 2.1% for 10 substances more.

  14. Recommended Correlations for the Surface Tension of Aliphatic, Carboxylic, and Polyfunctional Organic Acids

    Science.gov (United States)

    Mulero, A.; Cachadiña, I.; Sanjuán, E. L.

    2016-09-01

    In previous papers, we have proposed specific correlations to reproduce the surface tension values for several sets of fluids and for wide ranges of temperatures. In this paper, we focus our attention on organic fatty (aliphatic, carboxylic, and polyfunctional) acids. We have taken into account the available data and values in the DIPPR and DETHERM databases and also Wohlfarth and Wohlfarth's (1997) book. In some cases we have also considered new data published elsewhere. All the data and values have been carefully filtered and subsequently fitted with the use of the model currently implemented in NIST's REFPROP program, calculating two or four adjustable coefficients for each fluid. As a result, we propose recommended correlations for 99 acids, providing mean absolute percentage deviations below 1.6% in all cases.

  15. Pairwise Force Smoothed Particle Hydrodynamics model for multiphase flow: Surface tension and contact line dynamics

    Science.gov (United States)

    Tartakovsky, Alexandre M.; Panchenko, Alexander

    2016-01-01

    We present a novel formulation of the Pairwise Force Smoothed Particle Hydrodynamics (PF-SPH) model and use it to simulate two- and three-phase flows in bounded domains. In the PF-SPH model, the Navier-Stokes equations are discretized with the Smoothed Particle Hydrodynamics (SPH) method, and the Young-Laplace boundary condition at the fluid-fluid interface and the Young boundary condition at the fluid-fluid-solid interface are replaced with pairwise forces added into the Navier-Stokes equations. We derive a relationship between the parameters in the pairwise forces and the surface tension and static contact angle. Next, we demonstrate the model's accuracy under static and dynamic conditions. Finally, we use the Pf-SPH model to simulate three phase flow in a porous medium.

  16. Effect of Viscosity on the GTA Welds Bead Penetration in Relation with Surface Tension Elements

    Directory of Open Access Journals (Sweden)

    K. Touileb

    2016-04-01

    Full Text Available The aim of this paper is to study the effect of the viscous dissipation on the surface tension and its role on the shape of weld pool. Experiments were conducted on four different casts of ferritic stainless steel with different content in the sulfur and titanium. The results show in particular that the presence of titanium solid compounds affects the role of sulfur as surfactant element. Titanium in the presence of carbon and oxygen, titanium forms solid compounds which affect the Marangoni convection due to the sulfur element in the weld pool. The viscous dissipation due to these compounds alters the flow rate of the molten metal. We expect that the viscosity of metal liquid was altered by these solid compounds. The viscous dissipation due to these compounds contributes to heat the molten metal leading to larger weld bead.

  17. MHD-convection in a plane horizontal layer with surface tension

    Energy Technology Data Exchange (ETDEWEB)

    Liyepinya, V.R.

    1978-01-01

    The relation between critical values of the Marangoni number, the Rayleigh number, and the Hartmann number, expressed in terms of series whose convergence becomes slower with higher values of the Hartmann number, is extended to the case of thermal contact without perturbations between a horizontal layer of fluid and a solid heat conductor of finite thickness underneath. Heat transfer at the free upper boundary of this layer occurs according to Newton's law, and the boundary conditions here take into account surface tension as well as its temperature dependence. The limits of monotonic instability in a magnetic field are calculated from a numerical solution to this problem. 5 references, 1 figure, 1 table.

  18. Surface tension of liquid Al-Cu and wetting at the Cu/Sapphire solid-liquid interface

    Science.gov (United States)

    Schmitz, J.; Brillo, J.; Egry, I.

    2014-02-01

    For the study of the interaction of a liquid alloy with differently oriented single crystalline sapphire surfaces precise surface tension data of the liquid are fundamental. We measured the surface tension of liquid Al-Cu contactlessly on electromagnetically levitated samples using the oscillating drop technique. Data were obtained for samples covering the entire range of composition and in a broad temperature range. The surface tensions can be described as linear functions of temperature with negative slopes. Moreover, they decrease monotonically with an increase of aluminium concentration. The observed behaviour with respect to both temperature and concentration is in agreement with a thermodynamic model calculation using the regular solution approximation. Surface tensions were used to calculate interfacial energies from the contact angles of liquid Cu droplets, deposited on the C(0001), A(11-20), R(1-102) surfaces of an α-Al2O3 substrate. The contact angles were measured by means of the sessile drop method at 1380 K. In the Cu/α-Al2O3 system, no anisotropy is evident neither for the contact angles nor for the interfacial energies of different surfaces. The work of adhesion of this system is isotropic, too.

  19. A numerical study of three-dimensional surface tension driven convection with fre surface deformation

    Science.gov (United States)

    Hsieh, Kwang-Chung

    1992-01-01

    The steady three-dimensional thermocapillary motion with a deformable free surface is studied numerically in both normal and zero gravity environments. Flow configurations consist of a square cavity heated from the side. In the analysis, the free surface is allowed to deform and the grid distribution is adapted to the surface deformation. The divergence-free condition is satisfied by using a dual time-stepping approach in the numerical scheme. Convective flux derivatives are evaluated using a third-order accurate upwind-biased flux-split differencing technique. The numerical solutions at the midplane of the square cavity are compared with the results from two-dimensional calculations. In addition, numerial results for cases under zero and normal gravity conditions are compared. Significantly different flow structures and surface deformation have been observed. The comparison of calculated results will be compared with experimental data in the updated version of this paper.

  20. Elastic-Plastic J-Integral Solutions or Surface Cracks in Tension Using an Interpolation Methodology

    Science.gov (United States)

    Allen, P. A.; Wells, D. N.

    2013-01-01

    No closed form solutions exist for the elastic-plastic J-integral for surface cracks due to the nonlinear, three-dimensional nature of the problem. Traditionally, each surface crack must be analyzed with a unique and time-consuming nonlinear finite element analysis. To overcome this shortcoming, the authors have developed and analyzed an array of 600 3D nonlinear finite element models for surface cracks in flat plates under tension loading. The solution space covers a wide range of crack shapes and depths (shape: 0.2 less than or equal to a/c less than or equal to 1, depth: 0.2 less than or equal to a/B less than or equal to 0.8) and material flow properties (elastic modulus-to-yield ratio: 100 less than or equal to E/ys less than or equal to 1,000, and hardening: 3 less than or equal to n less than or equal to 20). The authors have developed a methodology for interpolating between the goemetric and material property variables that allows the user to reliably evaluate the full elastic-plastic J-integral and force versus crack mouth opening displacement solution; thus, a solution can be obtained very rapidly by users without elastic-plastic fracture mechanics modeling experience. Complete solutions for the 600 models and 25 additional benchmark models are provided in tabular format.

  1. A method for the determination of the surface tension of cellulosic fibres in their natural state and its relation with chemical composition

    NARCIS (Netherlands)

    Hazendonk, van J.M.; Putten, van der I.C.; Keurentjes, J.T.F.

    1995-01-01

    The surface tensions of several natural cellulosic fibres like flax, hemp, kenaf and cotton and a synthetic cellulosic fibre have been determined using the so-called floating test. This method determines the liquid surface tension δF at which fibres placed on a liquid surface remain just floating.

  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. Newtonian and general relativistic contribution of gravity to surface tension of strange stars

    CERN Document Server

    Bagchi, M; Dey, M; Dey, J; Bhowmick, S; Bagchi, Manjari; Sinha, Monika; Dey, Mira; Dey, Jishnu; Bhowmick, Siddhartha

    2005-01-01

    Surface tension (S) is due to the inward force experienced by particles at the surface and usually gravitation does not play an important role in this force. But in compact stars the gravitational force on the particles is very large and S is found to depend not only on the interactions in the strange quark matter, but also on the structure of the star, i.e. on its mass and radius. Indeed, it has been claimed recently that 511 keV photons observed by the space probe INTEGRAL from the galactic bulge may be due to electron-positron annihilation, and their source may be the positron cloud outside of an antiquark star. Such stars, if they exist, may also go a long way towards explaining away the antibaryon deficit of the universe. For that to happen S must be high enough to allow for survival of quark/antiquark stars born in early stages of the formation of the universe. High value of S may also assist explanation of delayed gamma-ray burst after a supernova explosion, as conversion from normal matter to strange ...

  4. CALCULATION OF CONTACT TENSIONS IN CONJUGATE SURFACES IN SPHERE GLOBOIDAL RUSK SYNCHRONOUS CARDAN HINGE

    Directory of Open Access Journals (Sweden)

    A. M. Saniotsky

    2015-01-01

    Full Text Available The paper presents  a calculation of contact tensions between conjugate surfaces in sphere globoidal rusk synchronous cardan hinge on the condition that there is power balance at the constant torque on the output shaft. The required torque effect on the intake shaft at the constant angular velocity  has been calculated with the help of the Hertz’s theory of contact deformations . The maximum contact pressure has been ascertained through the torque which determines strength of the cardan hinge, its durability, wear rate in  the conjugate friction pair. The paper investigates transmission dependence of the maximum torque while changing  material quality and according to various typical sizes of the cardan hinge. Dependences of the calculated maximum torque value on material strength have been demonstrated graphically  in the logarithmic coordinate system.  A formula for maximum contact pressure value has been derived and it determines  strength of the hinge mechanism, its durability and wear rate  in the conjugate friction pair.The effect of geometrical relationship between a spherical cam radius and a globoidal  surface radius of a hinge contact has been determined with the purpose to analyze optimal design parameters of the sphere globoidal rusk synchronous cardan hinge. It has been established that permissible torque in the hinge mechanism grows with a quadratic dependence while increasing a cam radius and  the torque is proportionally growing while increasing an axis radius of globoidal rusk surface on which spherical cams are set. The maximum permissible torque value grows with a cubic dependence while using qualitative material with thermally treated surface and application of lubrication materials which tolerates significant (up to [σ] = 1000 MPa contact loads.  Two-fold increase of typical size of the sphere globoidal rusk synchronous cardan hinge leads to an 8-fold increase of the permissible transmitted torque.

  5. Rhamnolipids elicit the same cytotoxic sensitivity between cancer cell and normal cell by reducing surface tension of culture medium.

    Science.gov (United States)

    Jiang, Lifang; Shen, Chong; Long, Xuwei; Zhang, Guoliang; Meng, Qin

    2014-12-01

    Biosurfactant rhamnolipids have been claimed to show biological activities of inhibiting the proliferation of cancer cells. In this study, the cytotoxicity of rhamnolipids was examined on four cancer cells (HepG2, Caco-2, Hela, MCF-7 cells) and two normal cells (HK-2 cell, primary hepatocyte). Interestingly, both cancer cells and normal cells exhibited similar sensitivities to the addition of rhamnolipids in culture medium, and the cytotoxicity was largely attenuated by the presence of fetal bovine serum (FBS) in culture medium. In correlation of the mono-/di-rhamnolipid cytotoxicity with the surface tension of culture medium, it was found that rhamnolipids triggered cytotoxicity whenever the surface tension of culture medium decreased below 41 mN/m irrespective of the FBS content in culture medium, cell line, or rhamnolipid congener. Similarly, each chemical surfactant (Tween-80, sodium dodecyl sulfate, and sodium dodecyl benzene sulfonate) could cause cytotoxicity on HepG2 cells whenever its addition made the surface tension under 41 mN/m in culture medium with or without the presence of FBS. It seems that rhamnolipids, like chemical surfactants, exhibited cytotoxicity by reducing the surface tension of culture medium rather than by changing its specific molecular structure, which had no selection on tumor cells. This study could offer helps to correct the misleading biological activity of rhamnolipids and to avoid the possible large wastes of time and expenses on developing the applications in antitumor drugs.

  6. Surface tension and its temperature coefficient of molten tin determined with the sessile drop method at different oxygen partial pressures.

    Science.gov (United States)

    Yuan, Zhang Fu; Mukai, Kusuhiro; Takagi, Katsuhiko; Ohtaka, Masahiko; Huang, Wen Lai; Liu, Qiu Sheng

    2002-10-15

    The surface tension of molten tin has been determined by the sessile drop method at temperatures ranging from 523 to 1033 K and in the oxygen partial pressure (P(O(2))) range from 2.85 x 10(-19) to 8.56 x 10(-6) MPa, and its dependence on temperature and oxygen partial pressure has been analyzed. At P(O(2))=2.85 x 10(-19) and 1.06 x 10(-15) MPa, the surface tension decreases linearly with the increase of temperature and its temperature coefficients are -0.151 and -0.094 mN m(-1) K(-1), respectively. However, at high P(O(2)) (3.17 x 10(-10), 8.56 x 10(-6) MPa), the surface tension increases with the temperature near the melting point (505 K) and decreases above 723 K. The surface tension decrease with increasing P(O(2)) is much larger near the melting point than at temperatures above 823 K. The contact angle between the molten tin and the alumina substrate is 158-173 degrees, and the wettability is poor.

  7. Determination of Surface Tension of Surfactant Solutions through Capillary Rise Measurements: An Image-Processing Undergraduate Laboratory Experiment

    Science.gov (United States)

    Huck-Iriart, Cristia´n; De-Candia, Ariel; Rodriguez, Javier; Rinaldi, Carlos

    2016-01-01

    In this work, we described an image processing procedure for the measurement of surface tension of the air-liquid interface using isothermal capillary action. The experiment, designed for an undergraduate course, is based on the analysis of a series of solutions with diverse surfactant concentrations at different ionic strengths. The objective of…

  8. 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.|info:eu-repo/dai/nl/074974424; 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

  9. 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 dynam

  10. Modelling the cloud condensation nucleus activity of organic acids on the basis of surface tension and osmolality measurements

    Directory of Open Access Journals (Sweden)

    Z. Varga

    2007-09-01

    Full Text Available In this study vapour pressure osmometry was used to determine water activity in the solutions of organic acids. The surface tension of the solutions was also monitored in parallel and then Köhler curves were calculated for nine organic acids (oxalic, malonic, succinic, glutaric, adipic, maleic, malic, citric and cis-pinonic. Surface tension depression is negligible for most of the organic acids in dilute (≤1 w/w% solutions. Therefore, these compounds affect equilibrium vapour pressure only in the beginning phase of droplet formation when the droplet solution is more concentrated but not necessarily at the critical size. An exception is cis-pinonic acid which remarkably depress surface tension also in dilute (0.1 w/w% solution and hence at the critical point. The surface tension of organic acid solutions is influenced by the solubility of the compound, the length of the carbon chain and also by the polar functional groups present in the molecule. Similarly to surface tension solubility plays an important role also in water activity: compounds with higher solubility (e.g. malonic, maleic and glutaric acid reduce water activity significantly in the early phase of droplet formation while less soluble acids (e.g. succinic and adipic acid are saturated in small droplets and the solution starts diluting only in bigger droplets. As a consequence, compounds with lower solubility have a minor effect on water activity in the early phase of droplet formation. To deduce the total effect Köhler curves were calculated and critical supersaturations (Sc were determined for the organic acids using measured surface tension and water activity. It was found that critical supersaturation grew with growing carbon number. Oxalic acid had the lowest critical supersaturation in the size range studied and it was comparable to the activation of ammonium sulphate. The Sc values obtained in this study were compared to data from CCNC

  11. A transferable force field to predict phase equilibria and surface tension of ethers and glycol ethers.

    Science.gov (United States)

    Ferrando, Nicolas; Lachet, Véronique; Pérez-Pellitero, Javier; Mackie, Allan D; Malfreyt, Patrice; Boutin, Anne

    2011-09-15

    We propose a new transferable force field to simulate phase equilibrium and interfacial properties of systems involving ethers and glycol ethers. On the basis of the anisotropic united-atom force field, only one new group is introduced: the ether oxygen atom. The optimized Lennard-Jones (LJ) parameters of this atom are identical whatever the molecule simulated (linear ether, branched ether, cyclic ether, aromatic ether, diether, or glycol ether). Accurate predictions are achieved for pure compound saturated properties, critical properties, and surface tensions of the liquid-vapor interface, as well as for pressure-composition binary mixture diagrams. Multifunctional molecules (1,2-dimethoxyethane, 2-methoxyethanol, diethylene glycol) have also been studied using a recently proposed methodology for the calculation of the intramolecular electrostatic energy avoiding the use of additional empirical parameters. This new force field appears transferable for a wide variety of molecules and properties. It is furthermore worth noticing that binary mixtures have been simulated without introducing empirical binary parameters, highlighting also the transferability to mixtures. Hence, this new force field gives future opportunities to simulate complex systems of industrial interest involving molecules with ether functions.

  12. Influence of the local morphology on the surface tension of injection molded polypropylene

    Science.gov (United States)

    Gomes, M.; Pontes, A. J.; Viana, J. C.

    2014-05-01

    In this work, we investigate the development of the morphology of an injection molding polypropylene under the local thermomechanical environment imposed during processing, and its effect on the contact angle and, hence, on the surface tension of the moldings. Melt and mold temperatures were varied in two levels. The local thermomechanical environment was characterized by mold filling computational simulations that allow the calculation of thermomechanical variables (e.g., local temperatures, shear stresses) and indices (related to the local morphology development). In order to investigate the structural hierarchy variations of the moldings in the thickness direction, samples from skin to core were used. The molecular orientation and degree of crystallinity were determined as function of the thickness, as well as the contact angle. The variations of the degree of crystallinity were assessed by differential scanning calorimetry. The level of molecular orientation was evaluated by birefringence measurements. The contact angles were measured in deionized water by sessile drop (needle in) method at room temperature, to determine the wettability of the samples. The contact angles were found to vary along the molding thickness in the skin, transition and core layers. These variations are related to the local morphologies developed. Results suggest that water contact angle increases with the level of molecular orientation and for finer microstructures.

  13. The self-interaction of a fluid interface, the wavevector dependent surface tension and wedge filling

    Science.gov (United States)

    Parry, Andrew O.; Rascón, Carlos

    2011-01-01

    We argue that whenever an interface, separating bulk fluid phases, adopts a non-planar configuration (induced by a confining geometry or thermal fluctuations, say), the energy cost of it will contain a non-local self-interaction term. For systems with short-ranged forces and Ising symmetry, we determine the self-interaction by integrating out bulk-like degrees of freedom from a more microscopic Landau-Ginzburg-Wilson model. The self-interaction can be written in a simple diagrammatic form involving integrals over effective two-body forces acting at the interface and consistently accounts for a number of known features of the microscopic model, including the wavevector dependence of the surface tension describing the fluctuations of a near planar interface. When applied to wedge filling transitions, the self-interaction describes the attraction between the wetting films on either side of the wedge. We show that, for sufficiently acute wedges, this can alter the order of the filling phase transition.

  14. The self-interaction of a fluid interface, the wavevector dependent surface tension and wedge filling

    Energy Technology Data Exchange (ETDEWEB)

    Parry, Andrew O [Department of Mathematics, Imperial College London, London SW7 2BZ (United Kingdom); Rascon, Carlos [Grupo Interdisciplinar de Sistemas Complejos (GISC), Departamento de Matematicas, Universidad Carlos III de Madrid, 28911 Leganes, Madrid (Spain)

    2011-01-12

    We argue that whenever an interface, separating bulk fluid phases, adopts a non-planar configuration (induced by a confining geometry or thermal fluctuations, say), the energy cost of it will contain a non-local self-interaction term. For systems with short-ranged forces and Ising symmetry, we determine the self-interaction by integrating out bulk-like degrees of freedom from a more microscopic Landau-Ginzburg-Wilson model. The self-interaction can be written in a simple diagrammatic form involving integrals over effective two-body forces acting at the interface and consistently accounts for a number of known features of the microscopic model, including the wavevector dependence of the surface tension describing the fluctuations of a near planar interface. When applied to wedge filling transitions, the self-interaction describes the attraction between the wetting films on either side of the wedge. We show that, for sufficiently acute wedges, this can alter the order of the filling phase transition.

  15. The utilization of round window membrane surface tension in facilitating slim electrodes insertion during cochlear implantation.

    Science.gov (United States)

    Nada, Ihab; Abdelhamid, Ahmed Nabil; Negm, Ahmed

    2017-06-24

    This is a prospective randomized study aimed to evaluate the round window membrane (RWM) surface tension in facilitating slim electrodes insertion during cochlear implantation. A total number of (118) children were included in this study (118 implantations). Mean age was 36.72 months (range from 18 to 60 months). This study was conducted from January 2015 to September 2016 at a cochlear implant centre in a tertiary referral hospital. Slit incision in the anterosuperior quadrant of the RWM was done in 70 cases, While RWM cruciate incision was done in 48 cases. Of the 48 patients who underwent RWM cruciate incision, 13 cases had no problem, while in 35 cases, we faced difficult insertion. When slit incision of the RWM was done (70 cases), 68 cases showed smooth insertion, meanwhile, we faced increased operative time due to flopping of the electrode in 2 cases only. Moreover, residual low-frequency hearing preservation was more achieved when slit incision of the RWM was done. Tensile strength of the round window membrane after slit incision of the RWM offers support to slim electrodes during introduction, decreasing incidence of kinking and floppiness, hence shortening the maneuver time and minimizing the number of trials. This facilitates easy smooth slim electrodes introduction, decreasing intracochlear trauma. Moreover, slit incision of the RWM may offer better residual hearing preservations than cruciate incision of the RWM during slim electrodes introduction.

  16. Pressure and surface tension of soild-liquid interface using Tarazona density functional theory

    Directory of Open Access Journals (Sweden)

    M. M.

    2000-12-01

    Full Text Available   The weighted density functional theory proposed by Tarazona is applied to study the solid-liquid interface. In the last two decades the weighted density functional became a useful tool to consider the properties of inhomogeneous liquids. In this theory, the role of the size of molecules or the particles of which the matter is composed, was found to be important. In this resarch we study a hard sphere fluid beside a hard wall. For this study the liquid is an inhomogeneous system. We use the definition of the direct correlation function as a second derivative of free energy with respect to the density. We use this definition and the definition of the weighting function, then we minimize the grand potential with respect to the density to get the Euler Lagrange equation and we obtain an integral equation to find the inhomogeneous density profile. The obtained density profile as a function of the distance from the wall, for different bulk density is plotted in three dimensions. We also calculate the pressure and compare it with the Carnahan-starling results, and finally we obtained the surface tension at liquid-solid interface and compared it with the results of Monte Carlo simulation.

  17. The self-interaction of a fluid interface, the wavevector dependent surface tension and wedge filling.

    Science.gov (United States)

    Parry, Andrew O; Rascón, Carlos

    2011-01-12

    We argue that whenever an interface, separating bulk fluid phases, adopts a non-planar configuration (induced by a confining geometry or thermal fluctuations, say), the energy cost of it will contain a non-local self-interaction term. For systems with short-ranged forces and Ising symmetry, we determine the self-interaction by integrating out bulk-like degrees of freedom from a more microscopic Landau-Ginzburg-Wilson model. The self-interaction can be written in a simple diagrammatic form involving integrals over effective two-body forces acting at the interface and consistently accounts for a number of known features of the microscopic model, including the wavevector dependence of the surface tension describing the fluctuations of a near planar interface. When applied to wedge filling transitions, the self-interaction describes the attraction between the wetting films on either side of the wedge. We show that, for sufficiently acute wedges, this can alter the order of the filling phase transition.

  18. New procedure to measure simultaneously the surface tension and contact angle

    Science.gov (United States)

    Champmartin, S.; Ambari, A.; Le Pommelec, J. Y.

    2016-05-01

    This paper proposes a new procedure to simultaneously measure the static contact angle and the surface tension of a liquid using a spherical geometry. Unlike the other existing methods, the knowledge of one of both previous parameters and the displacement of the sphere are not mandatory. The technique is based on the measurement of two simple physical quantities: the height of the meniscus formed on a sphere at the very contact with a liquid bath and the resulting vertical force exerted on this object at equilibrium. The meniscus height, whose exact value requires the numerical resolution of the Laplace equation, is often estimated with an approximate 2D model, valid only for very large spheres compared to the capillary length. We develop instead another simplified solution of the Young-Laplace equation based on the work of Ferguson for the meniscus on a cylinder and adapted for the spherical shape. This alternative model, which is less restrictive in terms of the sphere size, is successfully compared to numerical solutions of the complete Young-Laplace equation. It appears to be accurate for sphere radii larger than only two capillary lengths. Finally the feasibility of the method is experimentally tested and validated for three common liquids and two "small" steel spheres.

  19. Effect of surface tension on a liquid-jet produced by the collapse of a laser-induced bubble against a rigid boundary

    Science.gov (United States)

    Liu, Xiu Mei; He, Jie; Lu, Jian; Ni, Xiao Wu

    2009-02-01

    The effect of surface tension on the behavior of a liquid-jet is investigated experimentally by means of a fiber-coupled optical beam deflection (OBD) technique. It is found that a target under water is impacted in turn by a laser-plasma ablation force and by a high-speed liquid-jet impulse induced by bubble collapse in the vicinity of a rigid boundary. The liquid-jet impact is found to be the main damage mechanism in cavitation erosion. Furthermore, the liquid-jet increases monotonously with surface tension, so cavitation erosion rises sharply with increasing surface tension. Surface tension also reduces bubble collapse duration. From the experimental results and the modified Rayleigh theory, the maximum bubble radius is obtained and it is found to reduce with increasing surface tension.

  20. Assessment of Numerical Treatments in Interface Capturing Simulations for Surface-Tension-Driven Interface Motion

    Directory of Open Access Journals (Sweden)

    Abhinav Dhar

    2015-03-01

    Full Text Available Effects of numerical treatments for the surface tension evaluation on predictions of the motions of droplets ranging from micron to sub-micron meters were investigated. Various combinations of schemes for evaluating the normal to the interface and interface curvature were examined, i.e. the ALE (arbitrary Lagrangian-eulerian like scheme and BFA (balanced-force algorithm for the normal vector and CSF (continuum surface force and HF (height function for the interface curvature. The interface motion was predicted using THAINC (tangent of hyperbola with adaptive slope for interface capturing proposed in our previous study. Numerical errors in pressure and velocity were examined for neutrally buoyant drops of 1 mm in radius to validate the code, which confirmed that the results were similar to those reported in literature: the combination of BFA and HF gave the lowest errors. The droplet size was reduced to 0.1 mm to investigate the accuracy of the schemes for droplet sizes found in industrial coating processes. The static contact angle was then taken into account in the code. The effect of implementation on the errors was examined. The reduction of droplet sizes and implementation of contact angle had no substantial effect on the order of errors. A model for the dynamic contact angle was also implemented and the wetting behaviour of a drop of 1.14 mm in radius was well predicted. Finally a simulation of the wetting behaviour of a sub-micron meter droplet demonstrated that the present code combining BFA, HF and the dynamic contact angle model is accurate in predicting the motion of sub-micron meter droplets.

  1. Investigations of the surface tension of coal ash slags under gasification conditions; Untersuchungen zur Oberflaechenspannung von Kohleschlacken unter Vergasungsbedingungen

    Energy Technology Data Exchange (ETDEWEB)

    Melchior, Tobias

    2011-10-26

    In the context of CO{sub 2}-emission-induced global warming, greenhouse gases resulting from the production of electricity in coal-fired power plants gain increasing attention. One possible way to reduce such emissions is to gasify coal instead of burning it. The corresponding process is referred to as Integrated Gasification Combined Cycle and allows for the separation of CO{sub 2} before converting a synthesis gas into electrical energy. However, further improvements in efficiency and availability of this plant technology are needed to render the alternative generation of electricity sensible from an economic point of view. One corresponding approach introduces hot gas cleaning facilities to the gasification plant which guarantee a removal of slag particles from the synthesis gas at high temperatures. The development of such filters depends on the availability of data on the material properties of the coal ash slags to be withdrawn. In this respect, the surface tension is a relevant characteristic. Currently, the surface tension of real coal ash slags as well as of synthetic model systems was measured successfully by means of the sessile drop and the maximum bubble pressure method. With regard to the sessile drop technique, those experiments were conducted in a gasification-like atmosphere at temperatures of up to 1500 C. Furthermore, the pressure inside the experimental vessel was raised to 10 bar in order to allow for deriving the influence of this variable on the surface tension. In contrast, maximum bubble pressure trials were realised at atmospheric pressure while the gas atmosphere assured inert conditions. For performing sessile drop measurements, a corresponding apparatus was set up and is described in detail in this thesis. Three computer algorithms were employed to calculate surface tensions out of the photos of sessile drops and their individual performance was evaluated. A very good agreement between two of the codes was found while the third one

  2. A miniature surface tension-driven robot using spatially elliptical moving legs to mimic a water strider's locomotion.

    Science.gov (United States)

    Yan, J H; Zhang, X B; Zhao, J; Liu, G F; Cai, H G; Pan, Q M

    2015-08-04

    The highly agile and efficient water-surface locomotion of the water strider has stimulated substantial interest in biomimetic research. In this paper, we propose a new miniature surface tension-driven robot inspired by the water strider. A key feature of this robot is that its actuating leg possesses an ellipse-like spatial trajectory similar to that of a water strider by using a cam-link mechanism. Simplified models are presented to discuss the leg-water interactions as well as critical conditions for a leg penetrating the water surface, and simulations are performed on the robot's dynamic properties. The final fabricated robot weighs about 3.9 g, and can freely and stably walk on water at different gaits. The maximum forward and turning speeds of the robot are measured as 16 cm s(-1) and 23°/s, respectively. Furthermore, a similarity analysis with Bond number and Weber number demonstrates that the locomotion of this robot is quite analogous to that of a real water strider: the surface tension force dominates the lifting force and plays a major role in the propulsion force. This miniature surface tension-driven robot might have potential applications in many areas such as water quality monitoring and aquatic search and rescue.

  3. Reactive processing of formaldehyde and acetaldehyde in aqueous aerosol mimics: Surface tension depression and secondary organic products

    CERN Document Server

    Li, Zhi; Sareen, Neha; McNeill, V Faye

    2011-01-01

    The reactive uptake of carbonyl-containing volatile organic compounds (cVOCs) by aqueous atmospheric aerosols is a likely source of particulate organic material. The aqueous-phase secondary organic products of some cVOCs are surface-active. Therefore, cVOC uptake can lead to organic film formation at the gas-aerosol interface and changes in aerosol surface tension. We examined the chemical reactions of two abundant cVOCs, formaldehyde and acetaldehyde, in water and aqueous ammonium sulfate (AS) solutions mimicking tropospheric aerosols. Secondary organic products were identified using Aerosol Chemical Ionization Mass Spectrometry (Aerosol-CIMS), and changes in surface tension were monitored using pendant drop tensiometry. Hemiacetal oligomers and aldol condensation products were identified using Aerosol-CIMS. A hemiacetal sulfate ester was tentatively identified in the formaldehyde-AS system. Acetaldehyde depresses surface tension to 65(\\pm2) dyn/cm in pure water and 62(\\pm1) dyn/cm in AS solutions. Surface t...

  4. Mass transfer in fuel cells. [electron microscopy of components, thermal decomposition of Teflon, water transport, and surface tension of KOH solutions

    Science.gov (United States)

    Walker, R. D., Jr.

    1973-01-01

    Results of experiments on electron microscopy of fuel cell components, thermal decomposition of Teflon by thermogravimetry, surface area and pore size distribution measurements, water transport in fuel cells, and surface tension of KOH solutions are described.

  5. Molecular Dynamics Simulation of Surface Tension of NaCl Aqueous Solution at 298.15K: from Diluted to Highly Supersaturated Concentrations

    Science.gov (United States)

    Wang, Xiaoxiang; Chen, Chuchu; Poeschl, Ulirch; Su, Hang; Cheng, Yafang

    2017-04-01

    Sodium chloride (NaCl) is one of the key components of atmospheric aerosol particles. Concentration-depend surface tension of aqueous NaCl solution is essential to determine the equilibrium between droplet NaCl solution and water vapor, which is important in regards to aerosol-cloud interaction and aerosol climate effects. Although supersaturated NaCl droplets can be widely found under atmospheric conditions, the experimental determined concentration dependency of surface tension is limited up to the saturated concentration range due to technical difficulties, i.e., heterogeneous nucleation since nearly all surface tension measurement techniques requires contact of the sensor and solution surface. In this study, the surface tension of NaCl aqueous solution with solute mass fraction from 0 to 1 was calculated using molecular dynamics (MD) simulation. The surface tension increases monotonically and near linearly when mass fraction of NaCl (xNaCl) is lower than 0.265 (saturation point), which follows theoretical predictions (e.g., E-AIM, SP parameterization, and PK parameterization). Once entering into the supersaturated concentration range, the calculated surface tension starts to deviate from the near-linear extrapolation and adopts a slightly higher increasing rate until xNaCl of 0.35. We found that these two increasing phases (xNaCl 0.35) is mainly driven by the increase of excessive surface enthalpy when the solution becomes concentrated. After that, the surface tension remains almost unchanged until xNaCl of 0.52. This phenomenon is supported by the results from experiment based Differential Koehler Analyses. The stable surface tension in this concentration range is attributed to a simultaneous change of surface excess enthalpy and entropy at similar degree. When the NaCl solution is getting more concentrated than xNaCl of 0.52, the simulated surface tension regains an even faster growing momentum and shows the tendency of ultimately approaching the surface

  6. Wetting Angles and Surface Tension of Ge(1-x)Si(x) Melts on Different Substrate Materials

    Science.gov (United States)

    Croell, A.; Kaiser, N.; Szofran, F. R.; Cobb, S. D.; Volz, M. P.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    The wetting angles and the surface tension of Ge(1-x)Si(x) melts (0.02 less than x less than 0.13) have been measured on various substrate materials using the sessile drop technique. Fused quartz, sapphire, SiC, glassy carbon, pBN, AIN, and Si3N4 have been used as substrates. The highest and most stable wetting angles were found for pBN substrates with 164 +/- 8 deg., either under forming gas with an additional carbon getter in the system or under active vacuum. The surface tension measurements resulted in a value of +2.2 x 10(exp -3) N/m.at%Si for the concentration dependence delta(gamma)/(delta)C. For the composition range measured, the temperature dependence (delt)gamma/(delta)T showed values similar to those of pure Ge, on average -0.07 x 10(exp -3) N/mK.

  7. Influence of Zinc on the Surface Tension, Density and Molar Volume of (Ag-Sneut +Zn Liquid Alloys

    Directory of Open Access Journals (Sweden)

    Gąsior W.

    2016-03-01

    Full Text Available The dilatometric and maximum bubble pressure methods were applied for the measurements of the density and surface tension of liquid (Ag-Sneut +Zn lead-free solders. The experiments were carried out in the temperature range from 515 to 1223 K for the alloys of the zinc concentration equaling 0.01, 0.02, 0.04, 0.05, 0.1 and 0.2 of the mole fraction. It was found that the temperature dependence of both the density and the surface tension could be thought as linear, so they were interpreted by straight line equations. The experimental data of the molar volume of the investigated alloys were described by the polynomial dependent on the composition and temperature.

  8. The effect of a curvature-dependent surface tension on the singularities at the tips of a straight interface crack

    KAUST Repository

    Zemlyanova, A. Y.

    2013-03-08

    A problem of an interface crack between two semi-planes made out of different materials under an action of an in-plane loading of general tensile-shear type is treated in a semi-analytical manner with the help of Dirichlet-to-Neumann mappings. The boundaries of the crack and the interface between semi-planes are subjected to a curvature-dependent surface tension. The resulting system of six singular integro-differential equations is reduced to the system of three Fredholm equations. It is shown that the introduction of the curvature-dependent surface tension eliminates both classical integrable power singularity of the order 1/2 and an oscillating singularity present in a classical linear elasticity solutions. The numerical results are obtained by solving the original system of singular integro-differential equations by approximating unknown functions with Taylor polynomials. © 2013 The Author.

  9. Growth of a Gas Bubble in a Supersaturated Liquid Under the Effect of Variant Cases of Surface Tension

    Science.gov (United States)

    Mohammadein, S. A.; Mohamed, K. G.

    In this paper, the growth of a gas bubble in a supersaturated liquid is discussed for a constant and variable cases of surface tension effect. The mathematical model is solved analytically by using the method of Plesset and Zwick18 after modified it. The growth process is affected by: diffusion coefficient D, Jacob number Ja, surface tension σ, adjustment factor b and void fraction ϕ0. The famous formula of Plesset and Zwick is produced as a special case of the results at some values of the adjustment factors. Moreover, for some values of the adjustment factors, good approximation is obtained when a comparison between our results and the result that produced by Hashemi et al., 9 who solved the problem with the method of combining variables.

  10. Low-Bond Axisymmetric Drop Shape Analysis for Surface Tension and Contact Angle Measurements of Sessile Drops

    OpenAIRE

    Stalder, A.F.; Melchior, T.; Müller, M.; Sage, D; T. Blu; Unser, M

    2010-01-01

    A new method based on the Young-Laplace equation for measuring contact angles and surface tensions is presented. In this approach, a first-order perturbation technique helps to analytically solve the Young-Laplace equation according to photographic images of axisymmetric sessile drops. When appropriate, the calculated drop contour is extended by mirror symmetry so that reflection of the drop into substrate allows the detection of position of the contact points. To keep a wide range of applica...

  11. Conditions necessary for capillary hysteresis in porous media: Tests of grain-size and surface tension influences

    OpenAIRE

    Tokunaga, Tetsu K.; Olson, Keith R.; Wan, Jiamin

    2004-01-01

    Hysteresis in the relation between water saturation and matric potential is generally regarded as a basic aspect of unsaturated porous media. However, the nature of an upper length scale limit for saturation hysteresis has not been previously addressed. Since hysteresis depends on whether or not capillary rise occurs at the grain scale, this criterion was used to predict required combinations of grain size, surface tension, fluid-fluid density differences, and acceleration in monodisper...

  12. Wetting and Interfacial Tension Dynamics of Oil-Nanofluids-Surface Minerals System

    Science.gov (United States)

    Bai, L.; Li, C.; Darnault, C. J. G.; Korte, C.; Ladner, D.; Daigle, H.

    2015-12-01

    Among the techniques used in enhanced oil recovery (EOR), chemical injection involves the injection of surfactants to increase the oil mobility and decrease the interfacial tension (IFT). With the nanotechnology revolution, the use of nanoparticles has shown unique opportunities in petroleum engineering due to their physico-chemical properties. Our research examines the potential application of nanoparticles as a means of EOR by studying the influence of silicon oxide nanoparticles on the wettability and IFT of oil-nanofluids-surface systems. Batch studies were conducted to assess the stability of the nanoparticle suspensions of different concentrations (0, 0.001, 0.005, 0.01, 0.05 and 0.1 wt. %) in different reservoir conditions with and without the addition of surfactants (i.e. 5% brine, and Tween 20 at 0.5 and 2 cmc). Testing of oil-nanofluids and oil-nanofluids-minerals interactions was performed using crude oils from West Texas (light, API 40), Prudhoe Bay (medium, API 28), and Lloydminster (heavy, API 20). The dynamic behavior of IFT was measured using a pendant drop method. Results for 5% brine-nanoparticle systems indicated that 0.001 and 0.01 wt.% of nanoparticles contributed to a significant decrease of IFT for West Texas and Prudhoe Bay oils, while the highest decrease of IFT for Lloydminster was reported with 0.1 wt.% nanoparticles. IFT decrease was also enhanced by surfactant, and the addition of nanoparticles at 0.001 wt.% to surfactant resulted in significant decrease of IFT in most of the tested oil-nanofluid systems. The sessile drop method was used to measure the dynamic behavior of the contact angle of these oil droplets on minerals surface made of thin sections from Berea and Boise sandstone cores through a wetting test. Different nanofluid and surfactant concentrations were tested for the optimization of changes in wettability, which is a critical phase in assessing the behavior of nanofluids for optimal EOR with the selected crude oils.

  13. Multiphase Allen-Cahn and Cahn-Hilliard models and their discretizations with the effect of pairwise surface tensions

    Science.gov (United States)

    Wu, Shuonan; Xu, Jinchao

    2017-08-01

    In this paper, the mathematical properties and numerical discretizations of multiphase models that simulate the phase separation of an N-component mixture are studied. For the general choice of phase variables, the unisolvent property of the coefficient matrix involved in the N-phase models based on the pairwise surface tensions is established. Moreover, the symmetric positive-definite property of the coefficient matrix on an (N - 1)-dimensional hyperplane - which is of fundamental importance to the well-posedness of the models - can be proved equivalent to some physical condition for pairwise surface tensions. The N-phase Allen-Cahn and N-phase Cahn-Hilliard equations can then be derived from the free-energy functional. A natural property is that the resulting dynamics of concentrations are independent of phase variables chosen. Finite element discretizations for N-phase models can be obtained as a natural extension of the existing discretizations for the two-phase model. The discrete energy law of the numerical schemes can be proved and numerically observed under some restrictions pertaining to time step size. Numerical experiments including the spinodal decomposition and the evolution of triple junctions are described in order to investigate the effect of pairwise surface tensions.

  14. Thermocapillary-driven motion of a sessile drop: effect of non-monotonic dependence of surface tension on temperature.

    Science.gov (United States)

    Karapetsas, George; Sahu, Kirti Chandra; Sefiane, Khellil; Matar, Omar K

    2014-04-22

    We study the thermocapillary-driven spreading of a droplet on a nonuniformly heated substrate for fluids associated with a non-monotonic dependence of the surface tension on temperature. We use lubrication theory to derive an evolution equation for the interface that accounts for capillarity and thermocapillarity. The contact line singularity is relieved by using a slip model and a Cox-Voinov relation; the latter features equilibrium contact angles that vary depending on the substrate wettability, which, in turn, is linked to the local temperature. We simulate the spreading of droplets of fluids whose surface tension-temperature curves exhibit a turning point. For cases wherein these turning points correspond to minima, and when these minima are located within the droplet, then thermocapillary stresses drive rapid spreading away from the minima. This gives rise to a significant acceleration of the spreading whose characteristics resemble those associated with the "superspreading" of droplets on hydrophobic substrates. No such behavior is observed for cases in which the turning point corresponds to a surface tension maximum.

  15. Efficient numerical methods for simulating surface tension of multi-component mixtures with the gradient theory of fluid interfaces

    KAUST Repository

    Kou, Jisheng

    2015-08-01

    Surface tension significantly impacts subsurface flow and transport, and it is the main cause of capillary effect, a major immiscible two-phase flow mechanism for systems with a strong wettability preference. In this paper, we consider the numerical simulation of the surface tension of multi-component mixtures with the gradient theory of fluid interfaces. Major numerical challenges include that the system of the Euler-Lagrange equations is solved on the infinite interval and the coefficient matrix is not positive definite. We construct a linear transformation to reduce the Euler-Lagrange equations, and naturally introduce a path function, which is proven to be a monotonic function of the spatial coordinate variable. By using the linear transformation and the path function, we overcome the above difficulties and develop the efficient methods for calculating the interface and its interior compositions. Moreover, the computation of the surface tension is also simplified. The proposed methods do not need to solve the differential equation system, and they are easy to be implemented in practical applications. Numerical examples are tested to verify the efficiency of the proposed methods. © 2014 Elsevier B.V.

  16. Surface tensions, densities and refractive indexes of mixtures of dibutyl ether and 1-alkanol at T=298.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Rilo, Esther; Freire, Sonia; Segade, Luisa; Cabeza, Oscar. E-mail: oscabe@udc.es; Franjo, Carlos; Jimenez, Eulogio

    2003-05-01

    The aim of our present work is to present measurements of the surface tension, density and refractive index for binary mixtures of dibutyl ether with eight 1-alcohols {l_brace}C{sub 4}H{sub 9}OC{sub 4}H{sub 9}+C{sub 3}H{sub 7}OH,+C{sub 4}H{sub 9}OH,+C{sub 5}H{sub 11}OH,+C{sub 6}H{sub 13}OH,+C{sub 7}H{sub 15}OH,+C{sub =} 8H{sub 17}OH,+C{sub 9}H{sub 19}OH and +C{sub 10}H{sub 21}OH{r_brace} at the temperature of 298.15 K and atmospheric pressure. The experimental data are correlated by means of suitable empirical expressions, which relate the surface tension and refractive index of a mixture with its corresponding density. Also, calculated are the surface tension deviations and excess molar volumes from the measured data for all binary mixtures. The results of the study attending to the number of carbon atoms of the 1-alcohol are discussed.

  17. Improvements of the experimental apparatus for measurement of the surface tension of supercooled liquids using horizontal capillary tube

    Directory of Open Access Journals (Sweden)

    Vinš Václav

    2016-01-01

    Full Text Available An experimental apparatus with a horizontal capillary tube for measurement of the surface tension of supercooled liquids, i.e. liquids in a metastable state below the equilibrium freezing point, was designed and tested in the previous study [V. Vinš et al., EPJ Web Conf. 92, 02108 (2015]. In this work, recent modifications of both the experimental setup and the measurement analysis are described. The main aim is to improve the accuracy and the reproducibility of measured surface tension and to achieve higher degrees of supercooling. Temperature probes measuring the temperature of cooling medium near the horizontal capillary tube were calibrated in the relevant temperature range from – 31 °C to + 45 °C. An additional pressure transducer was installed in the helium distribution setup at the position close to the capillary tube. The optical setup observing the liquid meniscus at the open end of the horizontal capillary tube together with the video analysis were thoroughly revised. The red laser illuminating the liquid meniscus, used at the original apparatus, was replaced by a fiber optic light source, which significantly improved the quality of the meniscus image. The modified apparatus was used for the measurement of surface tension of supercooled water at temperatures down to – 11 °C. The new data have a lower scatter compared to the previous horizontal measurements and show a good agreement with the other data obtained with a different measurement technique based on the modified capillary rise method.

  18. Comparison of rheological, mechanical, electrical properties of HDPE filled with BaTiO3 with different polar surface tension

    Science.gov (United States)

    Su, Jun; Zhang, Jun

    2016-12-01

    In this work, three types of coupling agents: isopropyl trioleic titanate (NDZ105), vinyltriethoxysilane (SG-Si151), 3-aminopropyltriethoxysilane (KH550) were applied to modify the surface tension of Barium titanate (BaTiO3) particles. The Fourier transform infrared (FT-IR) spectra confirm the chemical adherence of coupling agents to the particle surface. The long hydrocarbon chains in NDZ105 can cover the particle surface and reduce the polar surface tension of BaTiO3 from 37.53 mJ/m2 to 7.51 mJ/m2, turning it from hydrophilic to oleophilic properties. The short and non-polar vinyl groups in SG-Si151 does not influence the surface tension of BaTiO3, but make BaTiO3 have both hydrophilic and oleophilic properties. The polar amino in KH550 can keep BaTiO3 still with hydrophilic properties. It is found that SG-Si151 modified BaTiO3 has the lowest interaction with HDPE matrix, lowering the storage modulus of HDPE composites to the greatest extent. As for mechanical properties, the polar amino groups in KH550 on BaTiO3 surface can improve the adhesion of BaTiO3 with HDPE matrix, which increases the elongation at break of HDPE composites to the greatest extent. In terms of electrical properties, the polar amino groups on surface of BaTiO3 can boost the dielectric properties of HDPE/BaTiO3 composites and decrease the volume resistivity of HDPE/BaTiO3 composites. The aim of this study is to investigate how functional groups affect the rheological, mechanical and electrical properties of HDPE composites and to select a coupling agent to produce HDPE/BaTiO3 composites with low dielectric loss, high dielectric constant and elongation at break.

  19. The Mechanical of the Small Axisymmetric Oscillations of the Liquid with the Surface Tension Forces in Elastic Tank

    Directory of Open Access Journals (Sweden)

    D. A. Goncharov

    2015-01-01

    Full Text Available In this paper we investigate small axisymmetric oscillations of a liquid in an elastic tank. We also take into account the influence of surface tension forces. For this, we turn to the mechanical analogue of the considered mechanical system. To realize the transition to mechanical analogue we use the energy method: postulating the equality of kinetic and potential energy for the investigated mechanical system and the mechanical system analog. Due to this transition we can further investigate the oscillations of a mechanical analogue. As a mechanical analogue, we consider the oscillator in the spring. The mass of the oscillator is calculated as the weight of the fluid to make oscillations. The oscillator spring constant is calculated using the identity of equations, namely, equation of free small oscillations of the oscillator and equation of free small oscillations of the system under investigation: the fluid in the elastic tank. The identity of equations allows us to draw conclusion about the identity of the natural frequencies for the source mechanical system and the system of a mechanical analogue. Next, we take into consideration the action of the surface tension. We record the Laplace condition for excess pressure because of the forces of surface tension. Then we compile the expression for the generalized force, taking into account the phenomenon of the surface tension. Next, we write the equation of oscillations of a mechanical analogue. The surface tension, due to the introduction of the generalized force in the equation for small oscillations of the mechanical analogue will change the natural frequency of the mechanical analogue. The paper presents the appropriate dependencies. The abovementioned allows us to investigate the stability of small motions of fluid in microgravity or low gravity by studying the stability of small motions of mechanical analogue. The latter is especially important due to the design and development of advanced

  20. Hydraulic Performance Modifications of a Zeolite Membrane after an Alkaline Treatment: Contribution of Polar and Apolar Surface Tension Components

    Directory of Open Access Journals (Sweden)

    Patrick Dutournié

    2015-01-01

    Full Text Available Hydraulic permeability measurements are performed on low cut-off Na-mordenite (MOR-type zeolites membranes after a mild alkaline treatment. A decrease of the hydraulic permeability is systematically observed. Contact angle measurements are carried out (with three polar liquids on Na-mordenite films seeded onto alumina plates (flat membranes. A decrease of the contact angles is observed after the alkaline treatment for the three liquids. According to the theory of Lifshitz-van der Waals interactions in condensated state, surface modifications are investigated and a variation of the polar component of the material surface tension is observed. After the alkaline treatment, the electron-donor contribution (mainly due to the two remaining lone electron pairs of the oxygen atoms present in the zeolite extra frameworks decreases and an increase of the electron-receptor contribution is observed and quantified. The contribution of the polar component to the surface tension is attributed to the presence of surface defaults, which increase the surface hydrophilicity. The estimated modifications of the surface interaction energy between the solvent (water and the Na-mordenite active layer are in good agreement with the decrease of the hydraulic permeability observed after a mild alkaline treatment.

  1. A multiphase three-dimensional multi-relaxation time (MRT) lattice Boltzmann model with surface tension adjustment

    Science.gov (United States)

    Ammar, Sami; Pernaudat, Guillaume; Trépanier, Jean-Yves

    2017-08-01

    The interdependence of surface tension and density ratio is a weakness of pseudo-potential based lattice Boltzmann models (LB). In this paper, we propose a 3D multi-relaxation time (MRT) model for multiphase flows at large density ratios. The proposed model is capable of adjusting the surface tension independently of the density ratio. We also present the 3D macroscopic equations recovered by the proposed forcing scheme. A high order of isotropy for the interaction force is used to reduce the amplitude of spurious currents. The proposed 3D-MRT model is validated by verifying Laplace's law and by analyzing its thermodynamic consistency and the oscillation period of a deformed droplet. The model is then applied to the simulation of the impact of a droplet on a dry surface. Impact dynamics are determined and the maximum spread factor calculated for different Reynolds and Weber numbers. The numerical results are in agreement with data published in the literature. The influence of surface wettability on the spread factor is also investigated. Finally, our 3D-MRT model is applied to the simulation of the impact of a droplet on a wet surface. The propagation of transverse waves is observed on the liquid surface.

  2. Fabrication of durable super-repellent surfaces on cotton fabric with liquids of varying surface tension: Low surface energy and high roughness

    Science.gov (United States)

    Singh, Arun K.; Singh, Jayant K.

    2017-09-01

    In this study, we have developed super-repellent surface on cotton fabric via a facile and eco-friendly strategy using zirconia particles with water-soluble siloxane emulsion. The coated fabric using zirconia-siloxane (ZS) coating showed super-repellency of liquids with surface tension >47.7 mN/m, like water, mixtures of isopropyl alcohol with deionized water (2% and 5%, v/v), and ethylene glycol with contact angle of 158°, 155°, 153° and 152°, respectively. Furthermore, the coated fabric displays low sliding angle, materials with ability to repel water in the presence of oily pollutants are very useful in application related to sea water. Thus as-prepared coated fabric, with dual functionality, is a promising material for many applications including anti-wetting, self-cleaning, support for aquatic floating devices and as a filtration material for rapid and continuous oil-water separation.

  3. Effect of surface tension on self-termination in Au tip fabrication for tip-enhanced Raman spectroscopy

    Science.gov (United States)

    Chaunchaiyakul, Songpol; Yano, Takeshi; Krukowski, Pawel; Kuwahara, Yuji

    2016-09-01

    The effect of surface tension on the fabrication of Au tips was investigated. When using a 12 M HCl aqueous solution, the etching process did not consistently self-terminate after the lower part of the wire dropped, resulting in the poor reproducibility of the tip sharpness. However, using an ethanolic solution of 12 mol/l HCl, a self-terminating etching process was always observed, resulting in the improved reproducibility of sharp tips. We attribute this to the reduced surface compared to that of aqueous HCl. The obtained tips were used in tip-enhanced Raman spectroscopy experiments, in which significant signal enhancement was observed.

  4. Solid/liquid interfacial tension as a tool to study stability of lysozyme on adsorption to solid surfaces

    Science.gov (United States)

    Krishnan, C. A.; Maheshwari, R.; Dhathathreyan, A.

    2006-01-01

    This work proposes the use of solid/liquid interfacial tension to study the stability of adsorbed lysozyme films on a solid surface using the contact angle of a liquid at the three phase contact line, in the presence of a denaturant, urea. Results suggest a direct correlation between this method with a standard technique like the fluorescence emission spectra and is measured with the same observable error as in the spectral methods. Further the technique provides a simple and direct handle to evaluate the homogeneity and degree of polarity of protein films on solid surfaces.

  5. Morphology observation for surface orange peel and fracture in tension sample of aluminum-alloy sheet and characterization of nano hardness

    Institute of Scientific and Technical Information of China (English)

    Ma Mingtu; Mei Huashen; Lu Hongzhou; Yang Hongya; Wu Emei; Zhou Mingbo

    2012-01-01

    The tension property of aluminum-alloy sheet with different microstructures is measured, and the surface and tension fracture morphology of tension sample with and without orange peel are observed by using scanning electron microscope (SEM). Surface roughness and nano hardness of tension sample are measured. The results show that the average elongation of the samples with orange peel is lower than that without orange peel ; especially the r value of per- pendicular to the rolling direction is much lower than that without orange peel. The tension surface of the orange peel samples is very rough; various parameters of surface roughness are higher. Under the observation of SEM, a wider slid- ing band with a micro crack on the surface of orange peel sample can be found. The various parameters of surface rough- ness without orange peel sample are near to zero, the sliding band is narrow and without micro cracks. The dimple width in tensile fracture of orange peel sample is larger than that without orange peel sample, but shear lip is narrower. The nano hardness testing results show that samples with orange peel behave high elastic modulus, high hardness, and high maximum load, but low plastic deformation depth. These mentioned features can completely describe surface and frac- ture morphology of tension samt31es with oranze peel.

  6. 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...

  7. Direct Monte Carlo Measurement of the Surface Tension in Ising Models

    CERN Document Server

    Hasenbusch, M

    1992-01-01

    I present a cluster Monte Carlo algorithm that gives direct access to the interface free energy of Ising models. The basic idea is to simulate an ensemble that consists of both configurations with periodic and with antiperiodic boundary conditions. A cluster algorithm is provided that efficently updates this joint ensemble. The interface tension is obtained from the ratio of configurations with periodic and antiperiodic boundary conditions, respectively. The method is tested for the 3-dimensional Ising model.

  8. Effect of surface tension, viscosity, and process conditions on polymer morphology deposited at the liquid-vapor interface.

    Science.gov (United States)

    Haller, Patrick D; Bradley, Laura C; Gupta, Malancha

    2013-09-17

    We have observed that the vapor-phase deposition of polymers onto liquid substrates can result in the formation of polymer films or particles at the liquid-vapor interface. In this study, we demonstrate the relationship between the polymer morphology at the liquid-vapor interface and the surface tension interaction between the liquid and polymer, the liquid viscosity, the deposition rate, and the deposition time. We show that the thermodynamically stable morphology is determined by the surface tension interaction between the liquid and the polymer. Stable polymer films form when it is energetically favorable for the polymer to spread over the surface of the liquid, whereas polymer particles form when it is energetically favorable for the polymer to aggregate. For systems that do not strongly favor spreading or aggregation, we observe that the initial morphology depends on the deposition rate. Particles form at low deposition rates, whereas unstable films form at high deposition rates. We also observe a transition from particle formation to unstable film formation when we increase the viscosity of the liquid or increase the deposition time. Our results provide a fundamental understanding about polymer growth at the liquid-vapor interface and can offer insight into the growth of other materials on liquid surfaces. The ability to systematically tune morphology can enable the production of particles for applications in photonics, electronics, and drug delivery and films for applications in sensing and separations.

  9. Butler-Sugimoto monomolecular bilayer interface model: the effect of oxygen on the surface tension of a liquid metal and its wetting of a ceramic.

    Science.gov (United States)

    Yen, Pei-Shan; Datta, Ravindra

    2014-07-15

    The influence of oxygen on liquid-gas surface tension of molten metals has been well-investigated experimentally and modeled theoretically via the Szyszkowski equation, derivable from the Butler molecular monolayer interface model. However, there is no corresponding model describing the experimentally observed profound effect of oxygen partial pressure on solid-liquid surface tension as well as on contact angle of molten metals on ceramic substrates. Here, we utilize the Butler-Sugimoto thermodynamic approach based on a monomolecular bilayer interface model to investigate the effect of oxygen partial pressure on liquid-gas as well as solid-liquid surface tension of molten Cu/Al2O3 and molten Ag/Al2O3 systems. It is shown that both liquid-gas and solid-liquid surface tension are a strong function of oxygen activity in the melt, which, in turn, depends on gas-phase oxygen partial pressure, in conformity with experiments. The change in solid-liquid surface tension and wetting is also greatly affected by the change in liquid-gas surface tension. This improved understanding is of practical significance in many applications.

  10. [Study of the surface tear tension and evaluation of its importance for the retinal physiology and pathology in contact correction and in adaptation to soft contact lenses].

    Science.gov (United States)

    Cherepnin, A I; Smoliakova, G P; Sorokin, E L

    2003-01-01

    The surface lachrymal-fluid (LF) tension was investigated by teardrop dissection in 115 patients with myopia before they were prescribed soft contact lenses (SCL). Such tension was found to be of clinical importance for the development of SCL adaptation disorders. A longer adaptation period in patients with myopia was associated with a low surface LF tension. A high surface LF tension concurrent with the teardrop dissection mode of the destruction type was typical of the pathological nature of SCL adaptation (12.1% of patients). The obtained data are needed to detect timely the risk of dysadaptation disorders and corneal complications before SCL prescription for the purpose of undertaking the pathogenetically substantiated medication to prevent such complications.

  11. Model HULIS compounds in nanoaerosol clusters – investigations of surface tension and aggregate formation using molecular dynamics simulations

    Directory of Open Access Journals (Sweden)

    T. Hede

    2011-07-01

    Full Text Available Cloud condensation nuclei act as cores for water vapour condensation, and their composition and chemical properties may enhance or depress the ability for droplet growth. In this study we use molecular dynamics simulations to show that model humic-like substances (HULIS in systems containing 10 000 water molecules mimic experimental data well referring to reduction of surface tension. The model HULIS compounds investigated in this study are cis-pinonic acid (CPA, pinic acid (PAD and pinonaldehyde (PAL. The structural properties examined show the ability for the model HULIS compounds to aggregate inside the nanoaerosol clusters.

  12. Analysis of effect of temperature gradients on surface-tension phenomena in gas-tungsten-arc welds

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H.A.; Chien, P.S.J.

    1982-10-01

    Fluid motion directed by surface tension is considered as a contributor to heat penetration in a weld pool. The potential phenomena at the gas-liquid interface were analyzed, and the dependence of surface motion on temperature in the gas-tungsten-arc (GTA) welding process was examined. An existing heat-transfer model was used and was able to predict weld size to +- 50% of the actual value. A momentum-transfer equation was derived by considering the contribution of Lorentz force. The momentum boundary condition was developed and was able to predict the Marangoni effect. The magnitude of surface-tension-driven force is comparable to the gravitational force on one gram. An empirical approach was proposed to couple heat-transfer and momentum-transfer phenomena. A dimensional analysis identified the pertinent dimensionless groups as Reynolds, Weber, Froude, Peclet, and Power numbers and a dimensionless velocity. A simplified form of the correction was developed by combining dimensionless groups to yield a correlation with the Bond, Prandtl, and modified power numbers. Future experimental work was proposed to test the functionality of the dimensionless groups.

  13. An apparatus with a horizontal capillary tube intended for measurement of the surface tension of supercooled liquids

    Directory of Open Access Journals (Sweden)

    Vinš Václav

    2015-01-01

    Full Text Available New experimental apparatus for measurement of the surface tension of liquids under the metastable supercooled state has been designed and assembled in the study. The measuring technique is similar to the method employed by P.T. Hacker [NACA TN 2510] in 1951. A short liquid thread of the liquid sample was sucked inside a horizontal capillary tube partly placed in a temperature-controlled glass chamber. One end of the capillary tube was connected to a setup with inert gas which allowed for precise tuning of the gas overpressure in order of hundreds of Pa. The open end of the capillary tube was precisely grinded and polished before the measurement in order to assure planarity and perpendicularity of the outer surface. The liquid meniscus at the open end was illuminated by a laser beam and observed by a digital camera. Application of an increasing overpressure of the inert gas at the inner meniscus of the liquid thread caused variation of the outer meniscus such that it gradually changed from concave to flat and subsequently convex shape. The surface tension at the temperature of the inner meniscus could be evaluated from the overpressure corresponding to exactly planar outer meniscus. Detailed description of the new setup together with results of the preliminary tests is provided in the study.

  14. Analysis of effect of temperature gradients on surface-tension phenomena in gas-tungsten-arc welds

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H.A.; Chien, P.S.J.

    1982-10-01

    Fluid motion directed by surface tension is considered as a contributor to heat penetration in a weld pool. The potential phenomena at the gas-liquid interface were analyzed, and the dependence of surface motion on temperature in the gas-tungsten-arc (GTA) welding process was examined. An existing heat-transfer model was used and was able to predict weld size to +- 50% of the actual value. A momentum-transfer equation was derived by considering the contribution of Lorentz force. The momentum boundary condition was developed and was able to predict the Marangoni effect. The magnitude of surface-tension-driven force is comparable to the gravitational force on one gram. An empirical approach was proposed to couple heat-transfer and momentum-transfer phenomena. A dimensional analysis identified the pertinent dimensionless groups as Reynolds, Weber, Froude, Peclet, and Power numbers and a dimensionless velocity. A simplified form of the correction was developed by combining dimensionless groups to yield a correlation with the Bond, Prandtl, and modified power numbers. Future experimental work was proposed to test the functionality of the dimensionless groups.

  15. The elimination of water-borne contaminants by a surface-tension based absorption system; Elimination de contaminants dans l`eau a l`aide d`un systeme d`absorption agissant sur la tension de surface

    Energy Technology Data Exchange (ETDEWEB)

    Paquin, J.; Panasuk, S.; Cote, B. [Sanexen Services Environnementaux inc., Longueuil, PQ (Canada)

    1997-12-31

    A new filtration method designed to remove colloidal or emulsified contaminants in water was described. The method, called Ultrasorption{sup T}M, employs an absorption technique by which the surface tension of water is increased. The method can successfully treat millions of litres of contaminated water in situations that would be problematic with conventional methods. Many water-borne contaminants such as polychlorinated biphenyls (PCBs), chlorophenols and low-polarity hydrocarbons such as polycyclic aromatic hydrocarbons (PAHs) are hydrophobic. The Ultrasorption method is based on the hydrophobic nature of these contaminants. It employs a special solvation agent that is integrated into the filtration matrix and is designed to capture the hydrophobic contaminants in the water. The solvation agent acts as both a demulsifier by increasing the surface tension of the water and as a fluid to allow the dissolution and retention of the contaminants. Results of trials at several sites in Quebec including Saint-Basile-le-Grand, Manic II, Saint-Amable and Smithville were presented. 5 refs., 3 tabs.

  16. Surface tensions of multi-component mixed inorganic/organic aqueous systems of atmospheric significance: measurements, model predictions and importance for cloud activation predictions

    Directory of Open Access Journals (Sweden)

    D. O. Topping

    2006-11-01

    Full Text Available In order to predict the physical properties of aerosol particles, it is necessary to adequately capture the behaviour of the ubiquitous complex organic components. One of the key properties which may affect this behaviour is the contribution of the organic components to the surface tension of aqueous particles in the moist atmosphere. Whilst the qualitative effect of organic compounds on solution surface tensions has been widely reported, our quantitative understanding on mixed organic and mixed inorganic/organic systems is limited.  Furthermore, it is unclear whether models that exist in the literature can reproduce the surface tension variability for binary and higher order multi-component organic and mixed inorganic/organic systems of atmospheric significance. The current study aims to resolve both issues to some extent. Surface tensions of single and multiple solute aqueous solutions were measured and compared with predictions from a number of model treatments. On comparison with binary organic systems, two predictive models found in the literature provided a range of values resulting from sensitivity to calculations of pure component surface tensions.  Results indicate that a fitted model can capture the variability of the measured data very well, producing the lowest average percentage deviation for all compounds studied.  The performance of the other models varies with compound and choice of model parameters. The behaviour of ternary mixed inorganic/organic systems was unreliably captured by using a predictive scheme and this was composition dependent. For more "realistic" higher order systems, entirely predictive schemes performed poorly. It was found that use of the binary data in a relatively simple mixing rule, or modification of an existing thermodynamic model with parameters derived from binary data, was able to accurately capture the surface tension variation with concentration. Thus, it would appear that in order to model

  17. Surface tension of dilute alcohol-aqueous binary fluids: n-Butanol/water, n-Pentanol/water, and n-Hexanol/water solutions

    Science.gov (United States)

    Cheng, Kuok Kong; Park, Chanwoo

    2017-01-01

    Surface tension of pure fluids, inherently decreasing with regard to temperature, creates a thermo-capillary-driven (Marangoni) flow moving away from a hot surface. It has been known that few high-carbon alcohol-aqueous solutions exhibit an opposite behavior of the surface tension increasing with regard to temperature, such that the Marangoni flow moves towards the hot surface (self-rewetting effect). We report the surface tensions of three dilute aqueous solutions of n-Butanol, n-Pentanol and n-Hexanol as self-rewetting fluids measured for ranges of alcohol concentration (within solubility limits) and fluid temperatures (25-85 °C). A maximum bubble pressure method using a leak-tight setup was used to measure the surface tension without evaporation losses of volatile components. It was found from this study that the aqueous solutions with higher-carbon alcohols exhibit a weak self-rewetting behavior, such that the surface tensions remain constant or slightly increases above about 60 °C. These results greatly differ from the previously reported results showing a strong self-rewetting behavior, which is attributed to the measurement errors associated with the evaporation losses of test fluids during open-system experiments.

  18. Combined Effect of Surface Tension, Gravity and van der Waals Force Induced by a Non-Contact Probe Tip on the Shape of Liquid Surface

    Institute of Scientific and Technical Information of China (English)

    LIU Nan; BAI Yi-Long; XIA Meng-Fen; KE Fu-Jiu

    2005-01-01

    @@ Aiming at understanding how a liquid film on a substrate affects the atomic force microscopic image in experiments, we present an analytical representation of the shape of liquid surface under van der Waals interaction induced by a non-contact probe tip. The analytical expression shows good consistence with the corresponding numerical results. According to the expression, we find that the vertical scale of the liquid dome is mainly gov erned by a combination of van der Waals force, surface tension and probe tip radius, and is weekly related to gravity. However, its horizontal extension is determined by the capillary length.

  19. Deleted in Malignant Brain Tumors 1 (DMBT1 is present in hyaline membranes and modulates surface tension of surfactant

    Directory of Open Access Journals (Sweden)

    Griese Matthias

    2007-10-01

    Full Text Available Abstract Background Deleted in Malignant Brain Tumors 1 (DMBT1 is a secreted scavenger receptor cysteine-rich protein that binds various bacteria and is thought to participate in innate pulmonary host defense. We hypothesized that pulmonary DMBT1 could contribute to respiratory distress syndrome in neonates by modulating surfactant function. Methods DMBT1 expression was studied by immunohistochemistry and mRNA in situ hybridization in post-mortem lungs of preterm and full-term neonates with pulmonary hyaline membranes. The effect of human recombinant DMBT1 on the function of bovine and porcine surfactant was measured by a capillary surfactometer. DMBT1-levels in tracheal aspirates of ventilated preterm and term infants were determined by ELISA. Results Pulmonary DMBT1 was localized in hyaline membranes during respiratory distress syndrome. In vitro addition of human recombinant DMBT1 to the surfactants increased surface tension in a dose-dependent manner. The DMBT1-mediated effect was reverted by the addition of calcium depending on the surfactant preparation. Conclusion Our data showed pulmonary DMBT1 expression in hyaline membranes during respiratory distress syndrome and demonstrated that DMBT1 increases lung surface tension in vitro. This raises the possibility that DMBT1 could antagonize surfactant supplementation in respiratory distress syndrome and could represent a candidate target molecule for therapeutic intervention in neonatal lung disease.

  20. Surface Tension Flows inside Surfactant-Added Poly(dimethylsiloxane Microstructures with Velocity-Dependent Contact Angles

    Directory of Open Access Journals (Sweden)

    Jyh Jian Chen

    2014-03-01

    Full Text Available Filling of liquid samples is realized in a microfluidic device with applications including analytical systems, biomedical devices, and systems for fundamental research. The filling of a disk-shaped polydimethylsiloxane (PDMS microchamber by liquid is analyzed with reference to microstructures with inlets and outlets. The microstructures are fabricated using a PDMS molding process with an SU-8 mold. During the filling, the motion of the gas-liquid interface is determined by the competition among inertia, adhesion, and surface tension. A single ramp model with velocity-dependent contact angles is implemented for the accurate calculation of surface tension forces in a three-dimensional volume-of-fluid based model. The effects of the parameters of this functional form are investigated. The influences of non-dimensional parameters, such as the Reynolds number and the Weber number, both determined by the inlet velocity, on the flow characteristics are also examined. An oxygen-plasma-treated PDMS substrate is utilized, and the microstructure is modified to be hydrophilic. Flow experiments are conducted into both hydrophilic and hydrophobic PDMS microstructures. Under a hydrophobic wall condition, numerical simulations with imposed boundary conditions of static and dynamic contact angles can successfully predict the moving of the meniscus compared with experimental measurements. However, for a hydrophilic wall, accurate agreement between numerical and experimental results is obvious as the dynamic contact angles were implemented.

  1. The surface tension of a solid at the solid-vacuum interface, an evaluation from adsorption and wall potential calculations.

    Science.gov (United States)

    Jakubov, Tim S; Mainwaring, David E

    2007-03-15

    A method for the evaluation of quantities that are experimentally inaccessible such as the surface tension at the solid-vacuum interface and the superficial tension of the fluid in contact with the solid is presented. The approach is based on consideration of an equilibrium of a fluid in solid capillary wherein a balance between surface and capillary forces has been replaced by conceptual alternative interfacial and centrifugal forces. This approach involves the simultaneous numerical solution one the special forms of the Gibbs equation for solid-fluid interface and a generalized Kelvin equation derived earlier. The latter equation takes into account interactions between the solid thick cylindrical wall and confined fluid, this body-body interaction potential has been primarily calculated using the Lennard-Jones (6-12) expression for the atom-atom pair potentials and expressed by hypergeometrical functions having good convergences. All numerical calculations shown here have been performed for the model graphite-argon system at 90 K. Finally, an analysis of the accuracy of the proposed method is considered.

  2. Buoyancy-driven detachment of a wall-bound pendant drop: Interface shape at pinchoff and nonequilibrium surface tension

    Science.gov (United States)

    Lamorgese, A.; Mauri, R.

    2015-09-01

    We present numerical results from phase-field simulations of the buoyancy-driven detachment of an isolated, wall-bound pendant emulsion droplet acted upon by surface tension and wall-normal buoyancy forces alone. Our theoretical approach follows a diffuse-interface model for partially miscible binary mixtures which has been extended to include the influence of static contact angles other than 90∘, based on a Hermite interpolation formulation of the Cahn boundary condition as first proposed by Jacqmin [J. Fluid Mech. 402, 57 (2000), 10.1017/S0022112099006874]. In a previous work, this model has been successfully employed for simulating triphase contact line problems in stable emulsions with nearly immiscible components, and, in particular, applied to the determination of critical Bond numbers for buoyancy-driven detachment as a function of static contact angle. Herein, the shapes of interfaces at pinchoff are investigated as a function of static contact angle and distance to the critical condition. Furthermore, we show numerical results on the nonequilibrium surface tension that help to explain the discrepancy between our numerically determined static contact angle dependence of the critical Bond number and its sharp-interface counterpart based on a static stability analysis of equilibrium shapes after numerical integration of the Young-Laplace equation. Finally, we show the influence of static contact angle and distance to the critical condition on the temporal evolution of the minimum neck radius in the necking regime of drop detachment.

  3. Density, viscosity, surface tension, and spectroscopic properties for binary system of 1,2-ethanediamine + diethylene glycol

    Energy Technology Data Exchange (ETDEWEB)

    Li, Lihua; Zhang, Jianbin, E-mail: tadzhang@pku.edu.cn; Li, Qiang; Guo, Bo; Zhao, Tianxiang; Sha, Feng

    2014-08-20

    Graphical abstract: Excess property of the binary system 1,2-ethanediamine (EDA) + diethylene glycol (DEG). - Highlights: • Densities and viscosities of EDA + DEG at 298.15–318.150 K were listed. • Thermodynamics data of EDA + DEG at 298.15–318.15 K were calculated. • Surface tension of EDA + DEG at 298.15 K was measured. • Intermolecular interaction of EDA with DEG was discussed. - Abstract: This paper reports density and viscosity data at T = 298.15, 303.15, 308.15, 313.15, and 318.15 K and surface tension data at 298.15 K for the binary system 1,2-ethanediamine (EDA) + diethylene glycol (DEG) as a function of composition under atmospheric pressure. From the experimental density and viscosity data, the excess molar volume and viscosity deviation were calculated, and the results were fitted to a Redlich–Kister equation to obtain the coefficients and to estimate the standard deviations between the experimental and calculated quantities. Based on the kinematic viscosity data, enthalpy of activation for viscous flow, entropy of activation for the viscous flow, and Gibbs energies of activation of viscous flow were calculated. In addition, based on Fourier transform infrared spectra, UV–vis spectra, and electrical conductivity for the system EDA + DEG with various concentrations, intermolecular interaction of EDA with DEG was discussed.

  4. Buoyancy-driven detachment of a wall-bound pendant drop: interface shape at pinchoff and nonequilibrium surface tension.

    Science.gov (United States)

    Lamorgese, A; Mauri, R

    2015-09-01

    We present numerical results from phase-field simulations of the buoyancy-driven detachment of an isolated, wall-bound pendant emulsion droplet acted upon by surface tension and wall-normal buoyancy forces alone. Our theoretical approach follows a diffuse-interface model for partially miscible binary mixtures which has been extended to include the influence of static contact angles other than 90^{∘}, based on a Hermite interpolation formulation of the Cahn boundary condition as first proposed by Jacqmin [J. Fluid Mech. 402, 57 (2000)JFLSA70022-112010.1017/S0022112099006874]. In a previous work, this model has been successfully employed for simulating triphase contact line problems in stable emulsions with nearly immiscible components, and, in particular, applied to the determination of critical Bond numbers for buoyancy-driven detachment as a function of static contact angle. Herein, the shapes of interfaces at pinchoff are investigated as a function of static contact angle and distance to the critical condition. Furthermore, we show numerical results on the nonequilibrium surface tension that help to explain the discrepancy between our numerically determined static contact angle dependence of the critical Bond number and its sharp-interface counterpart based on a static stability analysis of equilibrium shapes after numerical integration of the Young-Laplace equation. Finally, we show the influence of static contact angle and distance to the critical condition on the temporal evolution of the minimum neck radius in the necking regime of drop detachment.

  5. Pressure and surface tension of an active simple liquid: a comparison between kinetic, mechanical and free-energy based approaches.

    Science.gov (United States)

    Marini Bettolo Marconi, Umberto; Maggi, Claudio; Melchionna, Simone

    2016-06-29

    We discuss different definitions of pressure for a system of active spherical particles driven by a non-thermal coloured noise. We show that mechanical, kinetic and free-energy based approaches lead to the same result up to first order in the non-equilibrium expansion parameter. The first prescription is based on a generalisation of the kinetic mesoscopic virial equation and expresses the pressure exerted on the walls in terms of the average of the virial of the inter-particle forces. In the second approach, the pressure and the surface tension are identified with the volume and area derivatives, respectively, of the partition function associated with the known stationary non-equilibrium distribution of the model. The third method is a mechanical approach and is related to the work necessary to deform the system. The pressure is obtained by comparing the expression of the work in terms of local stress and strain with the corresponding expression in terms of microscopic distribution. This is determined from the force balance encoded in the Born-Green-Yvon equation. Such a method has the advantage of giving a formula for the local pressure tensor and the surface tension even in inhomogeneous situations. By direct inspection, we show that the three procedures lead to the same values of the pressure, and give support to the idea that the partition function, obtained via the unified coloured noise approximation, is more than a formal property of the system, but determines the stationary non-equilibrium thermodynamics of the model.

  6. COMPARISON OF INTERFACIAL SURFACE TENSION AND CAPILLARITY OF MAXILLARY COMPLETE DENTURES, FABRICATED BY CONVENTIONAL CUVETTE TECHNIQUE AND INJECTION MOLDING TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    Kalina Georgieva

    2016-09-01

    Full Text Available Purpose: The purpose of this in vivo study is to register the forces necessary to displace maxillary complete dentures fabricated by compression molding and injection molding techniques on one and the same patient and to compare the interfacial surface tension and capillarity which are achieved by both techniques. Material/Methods: Two maxillary complete dentures are made for each patient (total number of patients is 30 using both technologies. The magnitude of dislodging force is measured by a dynamometer. Results: Mean ± standard deviation for conventional cuvette technique is 17,53N ± 12,11N. Mean ± standard deviation for injection molding technique is 20,73N ± 13,89N. Analysis of variance (ANOVA revealed statistically significant differences in results achieved by conventional cuvette technique and injection molding technology. The results of injection technique were higher than those of compression molding technique (F=123,676, p< 0,001. Conclusions: Based on the results we suggest a standard for dislodging force of maxillary complete dentures fabricated by conventional cuvette technique- 13N, and by injection molding technology-15,5N. These values would guarantee good interfacial surface tension and capillarity. The injection molding technique was found to produce better fitting maxillary complete dentures when compared to compression molding technique. This would ensure better retention, less traumatic manifestations after insertion and higher patient’s comfort and satisfaction.

  7. Surface tension and disjoining pressure of free-standing smectic films above the bulk smectic-A-isotropic transition temperature

    Energy Technology Data Exchange (ETDEWEB)

    Zakharov, A. V., E-mail: avz0911@yahoo.com [Saint Petersburg Institute for Machine Sciences, The Russian Academy of Sciences, Saint Petersburg 199178 (Russian Federation); Śliwa, Izabela, E-mail: izasliwa@ifmpan.poznan.pl [Institute of Molecular Physics, Polish Academy of Sciences, Smoluchowskiego 17, 60-179 Poznan (Poland)

    2014-03-28

    We have carried out a numerical study of both the structural and thermodynamic properties of free-standing smectic films for the case of enhanced pair interaction in the bounding layers. Calculations, based upon the extended McMillan's mean-field theory with anisotropic forces, show that the layer-thinning transitions are characterized by abrupt drops to lower values, both for a disjoining pressure and a fluctuation-induced long-range interaction between the smectic film surfaces, and then continues to increase with a larger positive slope. Reasonable agreement between the theoretically predicted and the experimentally obtained data on the surface tension of the partially fluorinated 5-n-alkyl-2-(4-n-(perfluoroalkyl-metheleneoxy)phenyl) film has been obtained.

  8. Modeling of Surface Tension and Viscosity for Non-electrolyte Systems by Means of the Equation of State for Square-well Chain Fluids with Variable Interaction Range

    Institute of Scientific and Technical Information of China (English)

    LI Jinlong; HE Changchun; MA Jun; PENG Changjun; LIU Honglai; HU Ying

    2011-01-01

    The equation of state(EOS)for square-well chain fluid with variable range(SWCF-VR) developed in our previous work based on statistical mechanical theory for chemical association is employed for the correlations of surface tension and viscosity of common fluids and ionic liquids(ILs).A model of surface tension for multi-component mixtures is presented by combining the SWCF-VR EOS and the scaled particle theory and used to produce the surface tension of binary and ternary mixtures.The predicted surface tensions are in excellent agreement with the experimental data with an overall average absolute relative deviation(AAD)of 0.36%.A method for the calculation of dynamic viscosity of common fluids and ILs at high pressure is presented by combining Eyring’s rate theory of viscosity and the SWCF-VR EOS.The calculated viscosities are in good agreement with the experimental data with the overall AAD of 1.44% for 14 fluids in 84 cases.The salient feature is that the molecular parameters used in these models are self-consistent and can be applied to calculate different thermodynamic properties such as pVT,vapor-liquid equilibrium,caloric properties,surface tension,and viscosity.

  9. Surface tension of non-ideal binary and ternary liquid mixtures at various temperatures and p = 81.5 kPa

    Energy Technology Data Exchange (ETDEWEB)

    Rafati, A.A., E-mail: rafati_aa@yahoo.co [Department of Physical Chemistry, Faculty of Chemistry, Bu-Ali Sina University, Hamedan 65174 (Iran, Islamic Republic of); Bagheri, A. [Department of Physical Chemistry, Faculty of Chemistry, Bu-Ali Sina University, Hamedan 65174 (Iran, Islamic Republic of); Najafi, M. [Department of Material Engineering, Hamedan University of Technology, Hamedan (Iran, Islamic Republic of)

    2011-03-15

    Experimental surface tensions for binary mixtures (1,2-ethandiol + water), (1,2-ethandiol + acetonitrile), and (acetonitrile + water) at temperatures of 283.15 K, 298.15 K, and 308.15 K and the ternary mixture (1,2-ethandiol/water/acetonitrile) at 298.15 K have been measured with the Du Nouey ring tensiometer. The surface tension of the above mentioned binary and ternary systems were correlated with empirical and thermodynamic based models. The methods of Pando et al. and Ku et al. were used to correlate the ternary surface tension data. The Fu et al., Kalies et al. and Wang et al. models were also applied to predict surface tension in the ternary system. The mean average absolute deviations obtained from the comparison of experimental and calculated surface tension values for ternary system with three models are less than 2.4%, which leads to concluding that these models show a good accuracy in different situations in comparison with other predictive equations.

  10. Bacterial deposition to fluoridated and non-fluoridated polyurethane coatings with different elastic modulus and surface tension in a parallel plate and a stagnation point flow chamber

    NARCIS (Netherlands)

    Bakker, D.P.; Huijs, F.M.; Vries, J. de; Klijnstra, J.W.; Busscher, H.J.; Mei, H.C. van der

    2003-01-01

    Deposition of three marine bacterial strains with different cell surface hydrophobicities from artificial seawater to polyurethane coatings on glass with different surface tensions and elastic modulus was studied in situ in a parallel plate (PP) and stagnation point (SP) flow chamber. Different surf

  11. 静滴法测表面张力中各参数的确定%Parameters in Surface Tension Measured by Sessile Drop Method

    Institute of Scientific and Technical Information of China (English)

    陈安涛; 张胜全; 王胜

    2013-01-01

    Combining digital photography with AutoCAD and Proe,the parameters in surface tension measured by sessile drop method was determined.The results show that the method for calculating the surface tension has high accuracy,which can provide computer aid for adopting sessile drop method measuring high temperature metal surface tension.%应用致码撮影与电脑软件AutoCAD和Proe相结合的方法,确定静滴法计算表面张力公式中的各参数值.结果表明,该方法计算的表面张力具有较高精度,为静滴法测量高温金属表面张力提供电脑辅助.

  12. Improvements, testing and development of the ADM-{\\tau} sub-grid surface tension model for two-phase LES

    CERN Document Server

    Aniszewski, Wojciech

    2016-01-01

    In this paper, a specific subgrid term occurring in Large Eddy Simulation (LES) of two-phase flows is investigated. This and other subgrid terms are presented, we subsequently elaborate on the existing models for those and re-formulate the ADM-{\\tau} model for sub-grid surface tension previously published by these authors. This paper presents a substantial, conceptual simplification over the original model version, accompanied by a decrease in its computational cost. At the same time, it addresses the issues the original model version faced, e.g. introduces non-isotropic applicability criteria based on resolved interface's principal curvature radii. Additionally, this paper introduces more throughout testing of the ADM-{\\tau}, in both simple and complex flows.

  13. Variant of a volume-of-fluid method for surface tension-dominant two-phase flows

    Indian Academy of Sciences (India)

    G Biswas

    2013-12-01

    The capabilities of the volume-of-fluid method for the calculation of surface tension-dominant two-phase flows are explained. The accurate calculation of the interface remains a problem for the volume-of-fluid method if the density ratios of the fluids in different phases are high. The simulations of bubble growth is performed in water at near critical pressure for different degrees of superheat using combined levelset and volume-of fluid (CLSVOF) method. The effect of superheat on the frequency of bubble formation was analyzed. A deviation from the periodic bubble release is observed in the case of superheat of 20 K in water. The vapor-jet-like columnar structure is observed. Effect of heat flux on the slender vapor column has also been explained.

  14. Influence of Contact Angle, Growth Angle and Melt Surface Tension on Detached Solidification of InSb

    Science.gov (United States)

    Wang, Yazhen; Regel, Liya L.; Wilcox, William R.

    2000-01-01

    We extended the previous analysis of detached solidification of InSb based on the moving meniscus model. We found that for steady detached solidification to occur in a sealed ampoule in zero gravity, it is necessary for the growth angle to exceed a critical value, the contact angle for the melt on the ampoule wall to exceed a critical value, and the melt-gas surface tension to be below a critical value. These critical values would depend on the material properties and the growth parameters. For the conditions examined here, the sum of the growth angle and the contact angle must exceed approximately 130, which is significantly less than required if both ends of the ampoule are open.

  15. Molecular dynamics determination of the surface tension of silver-gold liquid alloys and the Tolman length of nanoalloys

    Science.gov (United States)

    Calvo, F.

    2012-04-01

    Using molecular dynamics simulations, an embedded-atom model potential, and the mechanistic route, we have computed the pressure tensor and the surface tension γ of Ag-Au liquid alloys. Although the model generally underestimates γ for pure metals, calculations for a bulk planar slab exhibit nonlinear variations of γ with increasing gold concentration, which agree with experiments and can be accounted for by a perfect solution model. Calculations for various nanoscale droplets containing between 100 and 3200 atoms show a systematic decrease of γ with increasing droplet radius R. The positive Tolman length of the alloy determined from these size variations is estimated to vary slightly with gold concentration. The effects of temperature in the range 1300-1700 K are discussed.

  16. Determining the association constant and adsorption properties of ion pairs in water by fitting surface tension data.

    Science.gov (United States)

    Pradines, Vincent; Lavabre, Dominique; Micheau, Jean-Claude; Pimienta, Véronique

    2005-11-22

    Association constants and adsorption parameters of tetraalkylammoniumdodecyl sulfate (TAADS) ion pairs in water were determined. We have analyzed water/air surface tension measurements obtained for mixtures of sodium dodecyl sulfate (SDS) and tetraalkylammonium bromide of increasing chain lengths (TMAB, TEAB, TPAB, and TBAB). To reproduce the experimental isotherms, we coupled the association equilibrium of the ion pairs to the equations proposed by Fainerman and co-workers to model the adsorption of binary mixtures of surfactants (SDS and TAADS) with different molar areas at a nonideal surface layer. The parameters found showed that the model is not convenient to describe the effect of the addition of TMAB but a clear coherency was obtained for the three longer compounds. Ranging from TEADS to TBADS increasing hydrophobic interactions give rise to a higher associability but to a lower surface activity. Self-interactions coefficients extracted by the fitting procedure confirmed the importance of attractive interactions between the ion pairs. The calculated surface coverage showed that in every case the compound mainly adsorbed at the interface was the ion pair. For TBADS strong attractive interactions result in a phase transition at very low concentration.

  17. Simultaneous decay of contact-angle and surface-tension during the rehydration of air-dried root mucilage

    Science.gov (United States)

    Arye, Gilboa; Chen, Fengxian

    2016-04-01

    Plants can extract or exude water and solutes at their root surface. Among the root exudates, the mucilage exhibits a surfactant like properties - depressing the surface-tension (ST, mN/m) at the water-air interface. The amphipathic nature of some of the mucilage molecules (e.g. lipids) is thought to be the reason for its surfactant like behavior. As the rhizosphere dries out, re-orientation and/or re-configuration of amphipathic molecules at the solid-air interface, may impart hydrophobic nature to the rhizosphere. Our current knowledge on the ST of natural and/or model root mucilage is based on measurements of the equilibrium ST. However, adsorption of amphipathic molecules at the water-air interface is not reached instantaneously. The hydrophobic nature of the rhizosphere was deduced from the initial advancing CA, commonly calculated from the first few milliseconds up to few seconds (depending on the method employed). We hypothesized that during the rehydration of the root mucilage; both quantities are dynamic. Processes such as water absorbance and dissolution, may vary the interfacial tensions as a function of time. Consequently, simultaneous reduction of both CA and ST as a function of time can be expected. The main objective of this study was to characterize and quantify the extent, persistency and dynamic of the CA and ST during rehydration of air-dried root mucilage. The study was involved with measurements of dynamic and equilibrium ST using the pedant drop or Wilhelmy plate method, respectively. Glass slides were coated with naturally occurring or model root mucilage and the CA of a sessile drop was measured optically, as a function of time. The results were analyzed based on the Young-Dupré and Young-Laplace equations, from which the simultaneous decay of CA and ST was deduced. The implication for the wettability and water flow in the rhizosphere will be discussed.

  18. Type the title of your paper here Effect of the focused light from the xenon arc lamp on the surface tension of the molten enamel

    Science.gov (United States)

    Aleutdinov, A. D.; Ghyngazov, S. A.; Mylnikova, T. S.; Aleutdinov, K. A.

    2016-02-01

    The effect of exposure to the focused light from the xenon arc lamp on the surface tension of molten enamels was studied with a designed light beam setup as compared to that observed in conventional heating in a resistance furnace. The objects under investigation were enamels No. 261, UES-200 and UES-300. The power density of the light beam was varied in the range of (30-80) W/cm2. When exposed to light, the surface tension is shown to be an order of magnitude lower than that obtained in conventional furnace heating.

  19. Molecular-Level Insight of the Effect of Hofmeister Anions on the Interfacial Surface Tension of a Model Protein

    Energy Technology Data Exchange (ETDEWEB)

    Willow, Soohaeng Yoo; Xantheas, Sotiris S.

    2017-03-21

    The effect of the Hofmeister anion series on the structure and stability of proteins is often discussed using simple systems such as a water-vapor interface with the assumption that the vapor region mimics the hydrophobic surface. Microscopic theories suggest that the Hofmeister anion series is highly correlated with the different contributions of the various ions to the surface tension of such a water-vapor interface. Proteins, however, have both hydrophobic and hydrophilic regions rather than just a pure hydrophobic one. Using a solvated parallel β -sheet layer consisting of both hydrophobic and positively charged hydrophilic surfaces as a more realistic model to represent a protein surface, we investigated the interaction of such a system with hydrophilic-like (SO42-) and hydrophobic-like (ClO4-) anions via Born-Oppenheimer Molecular Dynamics (BOMD) simulations. We found that both the SO42- and ClO4- anions prefer to reside on the hydrophilic rather than on the hydrophobic surface of the parallel β -sheet layer. In addition, our simulations suggest that the ClO4- ions not only penetrate towards the peptide groups through the hydrophilic residues, but also allow water molecules to penetrate as well to form water-peptide hydrogen bonds, while the SO42- ions stabilize the interface of the water-hydrophilic surface. Our results render a plausible explanation of why hydrophobic-like Hofmeister anions act as protein denaturants. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle.

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

    Science.gov (United States)

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

    2016-04-01

    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 dynamics of interfaces and contact lines on the continuum scale, appropriate formulations must be developed. While the Continuum Surface Force (CSF) model is well-engineered for the description of interfaces, there is still a lack of treatment of contact lines, which are defined by the intersection of an ending fluid interface and a solid boundary surface. In our approach we use a balance equation for the contact line and extend the Navier-Stokes equations in analogy to the extension of a two-phase interface in the CSF model. Since this model depicts a physically motivated approach on the continuum scale, no fitting parameters are introduced and the deterministic description leads to a dynamical evolution of the system. As verification of our theory, we show a Smoothed Particle Hydrodynamics (SPH) model and simulate the evolution of droplet shapes and their corresponding contact angles.

  1. Solubility of N2O in and density, viscosity, and surface tension of aqueous piperazine solutions

    NARCIS (Netherlands)

    Derks, P. W.; Hogendoorn, K. J.; Versteeg, G. F.

    2005-01-01

    The physical solubility of N2O in and the density and viscosity of aqueous piperazine solutions have been measured over a temperature range of (293.15 to 323.15) K for piperazine concentrations ranging from about (0.6 to 1.8) kmol·mr-3. Furthermore, the present study contains experimental surface

  2. Solubility of N2O in and density, viscosity, and surface tension of aqueous piperazine solutions

    NARCIS (Netherlands)

    Derks, P. W.; Hogendoorn, K. J.; Versteeg, G. F.

    2005-01-01

    The physical solubility of N2O in and the density and viscosity of aqueous piperazine solutions have been measured over a temperature range of (293.15 to 323.15) K for piperazine concentrations ranging from about (0.6 to 1.8) kmol·mr-3. Furthermore, the present study contains experimental surface t

  3. Curvature effects on the surface thickness and tension at the free interface of $^4$He systems

    OpenAIRE

    Szybisz, Leszek; Urrutia, Ignacio

    2003-01-01

    The thickness $W$ and the surface energy $\\sigma_A$ at the free interface of superfluid $^4$He are studied. Results of calculations carried out by using density functionals for cylindrical and spherical systems are presented in a unified way, including a comparison with the behavior of planar slabs. It is found that for large species $W$ is independent of the geometry. The obtained values of $W$ are compared with prior theoretical results and experimental data. Experimental data favor results...

  4. Basic surface properties of Aedes albopictus cells: effect of Mayaro virus infection on electrostatic charge and surface tension.

    Science.gov (United States)

    Mezêncio, J M; Costa e Silva Filho, F; Rebello, M A

    1997-01-01

    Aedes albopictus cells possess a negative cell surface charge of -12.7 mV with an isoelectrophoretic point (IEP) located between pH 3.0 and 4.0. Infection with Mayaro virus rendered the surface of A. albopictus cells less negative reaching a zeta-potential value of -9.7 mV after 100 h of infection. Concomitantly, the IEP of the infected cells were also altered from 3.0-4.0 to 4.0-5.0. Furthermore, the contact angle measurements clearly showed qualitative alterations in the cell surface of infected cells.

  5. Surface tensions of multi-component mixed inorganic/organic aqueous systems of atmospheric significance: measurements, model predictions and importance for cloud activation predictions

    Directory of Open Access Journals (Sweden)

    D. O. Topping

    2007-01-01

    Full Text Available In order to predict the physical properties of aerosol particles, it is necessary to adequately capture the behaviour of the ubiquitous complex organic components. One of the key properties which may affect this behaviour is the contribution of the organic components to the surface tension of aqueous particles in the moist atmosphere. Whilst the qualitative effect of organic compounds on solution surface tensions has been widely reported, our quantitative understanding on mixed organic and mixed inorganic/organic systems is limited. Furthermore, it is unclear whether models that exist in the literature can reproduce the surface tension variability for binary and higher order multi-component organic and mixed inorganic/organic systems of atmospheric significance. The current study aims to resolve both issues to some extent. Surface tensions of single and multiple solute aqueous solutions were measured and compared with predictions from a number of model treatments. On comparison with binary organic systems, two predictive models found in the literature provided a range of values resulting from sensitivity to calculations of pure component surface tensions. Results indicate that a fitted model can capture the variability of the measured data very well, producing the lowest average percentage deviation for all compounds studied. The performance of the other models varies with compound and choice of model parameters. The behaviour of ternary mixed inorganic/organic systems was unreliably captured by using a predictive scheme and this was dependent on the composition of the solutes present. For more atmospherically representative higher order systems, entirely predictive schemes performed poorly. It was found that use of the binary data in a relatively simple mixing rule, or modification of an existing thermodynamic model with parameters derived from binary data, was able to accurately capture the surface tension variation with concentration. Thus

  6. Impact of a Liquid Drop on a Granular Medium: inertia, viscosity and surface tension effects on the drop deformation

    CERN Document Server

    Nefzaoui, Elyes

    2010-01-01

    An experimental study of liquid drop impacts on a granular medium is proposed. Four fluids were used to vary physical properties: pure distilled water, water with glycerol at 2 concentrations 1:1 and 1:2 v/v and water with Tween 20 at the concentration of 0.1g/l. The drop free fall height was varied to obtain a Weber number (We) between 10 and 2000. Results showed that obtained crater morphologies highly depend on the impacting drop kinetic energy E_{K}. Different behaviours during the drop spreading, receding and absorption are highlighted as function of the fluids viscosity and surface tension. Experimental absorption times are also commented and compared with a simplified theoretical model. Drops maximal extensions and craters diameters were found to scale as $We^{1/5}$ and $E_K^{1/5}$ respectively. In both cases, found dependencies are smaller than those reported in literature: $We^{1/4}$ for drop impacts on solid or granular surfaces and $E_K^{1/4}$ for spherical solid impacts on granular media.

  7. On the characterization of host-guest complexes : Surface tension, calorimetry, and molecular dynamics of cyclodextrins with a non-ionic surfactant

    NARCIS (Netherlands)

    Pineiro, Angel; Banquy, Xavier; Perez-Casas, Silvia; Tovar, Edgar; Garcia, Abel; Villa, Alessandra; Amigo, Alfredo; Mark, Alan E.; Costas, Miguel

    2007-01-01

    Three host-guest systems have been characterized using surface tension (sigma), calorimetry, and molecular dynamics simulations (MD). The hosts were three native cyclodextrins (CD) and the guest the non-ionic carbohydrate surfactant octyl-beta-d-glucopyranoside. It is shown that, for any host-guest

  8. On the characterization of host-guest complexes : Surface tension, calorimetry, and molecular dynamics of cyclodextrins with a non-ionic surfactant

    NARCIS (Netherlands)

    Pineiro, Angel; Banquy, Xavier; Perez-Casas, Silvia; Tovar, Edgar; Garcia, Abel; Villa, Alessandra; Amigo, Alfredo; Mark, Alan E.; Costas, Miguel

    2007-01-01

    Three host-guest systems have been characterized using surface tension (sigma), calorimetry, and molecular dynamics simulations (MD). The hosts were three native cyclodextrins (CD) and the guest the non-ionic carbohydrate surfactant octyl-beta-d-glucopyranoside. It is shown that, for any host-guest

  9. Density gradient theory combined with the PC-SAFT equation of state used for modeling the surface tension of associating systems

    Directory of Open Access Journals (Sweden)

    Vinš Václav

    2014-03-01

    Full Text Available The density gradient theory (GT combined with a SAFT-type (Statistical Associating Fluid Theory equation of state has been used for modeling the surface tension of associating fluids represented by a series of six alkanols ranging from methanol to 1-pentanol. The effect of nonzero dipole moment of the selected alkanols on the predicted surface tension was investigated in this study. Results of the GT + non-polar Perturbed Chain (PC SAFT equation of state were compared to predictions of GT combined with the PC-polar-SAFT, i.e. PCP-SAFT, equation. Both GT + PC-SAFT and GT + PCP-SAFT give reasonable prediction of the surface tension for pure alkanols. Results of both models are comparable as no significant difference in the modeled saturation properties and in the predicted surface tension using GT was found. Consideration of dipolar molecules of selected alkanols using PCP-SAFT had only minor effect on the predicted properties compared to the non-polar PC-SAFT model.

  10. 表面张力系数实验的应用研究%On the Application of Liquid Surface Tension Coefficient Experiment

    Institute of Scientific and Technical Information of China (English)

    葛素红; 孙桂华; 王雅丽

    2014-01-01

    The surface tension coefficient of saline water and sweet water in the same temperature and different densities was measured using the FD-NST-I liquid surface tension coefficient measuring instrument. And the surface tension coefficient of tap -water and purified water in different temperatures was also measured using the same instrument. Results show that the surface tension coefficient is related to temperature and density.%应用拉脱法测量了食盐和白糖溶液的表面张力系数,发现:盐溶液的表面张力系数随着溶液密度的增大而增大,糖溶液的表面张力系数随着浓度的增大而减小。测量了自来水与纯净水在不同环境温度下的表面张力系数,验证了液体表面张力系数随着温度的升高而降低的物理规律。

  11. Improvement of Wetting Tension Values of Battery Foil Surface%电池箔表面润湿张力值的提高

    Institute of Scientific and Technical Information of China (English)

    陈志轩; 刘英超

    2015-01-01

    Measurement method of wetting tension of battery foil surface was introduced, as well as dyne value, liquid dyne, wettability, surface tension, contact angle and so on theoretical knowledge. The effect of rolling oil on surface wetting tension values was analyzed. Experiments show that the surface wetting tension value of the battery foil products can be improved using A70 base oil and about 8% additive proportion.%分析了轧制油对表面润湿张力值的影响,并根据基础油及添加剂比例配置了不同油样,设计了实验,验证不同油样对于产品表面润湿张力值的影响.实验表明,采用A70基础油和8%左右的添加剂比例可以提升电池箔产品的表面润湿张力值.

  12. Surface tension-induced PDMS micro-pillars with controllable tips and tilt angles

    KAUST Repository

    Li, Huawei

    2013-12-21

    This paper reports a novel method to fabricate three-dimensional (3D) polydimethylsiloxane (PDMS) micro-pillars using a CO2 laser-machined poly(methyl methacrylate) (PMMA) mold with through-holes. This method eliminates the requirements of expensive and complicated facilities to fabricate a 3D mold. The micro-pillars were formed by the capillary force that draws PDMS into the through-holes of the PMMA mold. The tilt angles of the micro-pillars depend on the tilt angles of the through-holes in the mold, and the concave and convex micro-lens tip shapes of the PDMS micro-pillars can be modified by changing the surface wettability of the PMMA through-holes.

  13. Long-Wavelength Rupturing Instability in Surface-Tension-Driven Benard Convection

    Science.gov (United States)

    Swift, J. B.; Hook, Stephen J. Van; Becerril, Ricardo; McCormick, W. D.; Swinney, H. L.; Schatz, Michael F.

    1999-01-01

    A liquid layer with a free upper surface and heated from below is subject to thermocapillary-induced convective instabilities. We use very thin liquid layers (0.01 cm) to significantly reduce buoyancy effects and simulate Marangoni convection in microgravity. We observe thermocapillary-driven convection in two qualitatively different modes, short-wavelength Benard hexagonal convection cells and a long-wavelength interfacial rupturing mode. We focus on the long-wavelength mode and present experimental observations and theoretical analyses of the long-wavelength instability. Depending on the depths and thermal conductivities of the liquid and the gas above it, the interface can rupture downwards and form a dry spot or rupture upwards and form a high spot. Linear stability theory gives good agreement to the experimental measurements of onset as long as sidewall effects are taken into account. Nonlinear theory correctly predicts the subcritical nature of the bifurcation and the selection between the dry spot and high spots.

  14. Curvature effects on the surface thickness and tension at the free interface of 4He systems

    Science.gov (United States)

    Szybisz, Leszek; Urrutia, Ignacio

    2003-08-01

    The thickness W and the surface energy σA at the free interface of superfluid 4He are studied. Results of calculations carried out using density functionals for cylindrical and spherical systems are presented in a unified way, including a comparison with the behavior of planar slabs. It is found that for large species W is independent of the geometry. The obtained values of W are compared with prior theoretical results and experimental data. Experimental data favor results evaluated by adopting finite range approaches. The behavior of σA and WσA exhibits overshoots similar to that found previously for the central density, and the trend of these observables towards their asymptotic values is examined.

  15. Investigation of wettability to evaluate the morphology and surface tension wood filler

    Directory of Open Access Journals (Sweden)

    S. T. Antipov

    2017-01-01

    Full Text Available In this paper, we propose a new scheme of a highly efficient line for preparing safflower grains for processing consisting of an air-sieve separator, a magnetic separator, an ovary, a puppet, and a stone picker. The new after vortex separator is a vibroseparator for separating the products close in physical properties, grinding Machine with a duo-aspirator, a photoseparator and a device for moisture-thermal treatment. Advantages of the proposed line for preparation of safflower grain for processing are that an additional plant in front of the photocarerator of the grinding machine and duo-espirator allows the crest to separate and remove or refine the shell of the seed in the form of a shell layer for more efficient subsequent spectral point analysis, which determines the grain composition for the purpose of sorting it On the basis of chemical composition and color in the photo separator, and sequential placement after the stone separator of a vibro separator for separation of products close in physical properties, a grinding machine with a duo-aspirator, a photoseparator and a device for moisture-thermal treatment, provides an intensification of the technological process of efficient separation of safflower from impurities and its preparation for further processing and Due to the rational layout of equipment.A highly efficient photocell separator is also provided, the advantages of which are that the installation of a storage and vibrating feeder in relation to the slanting tray from the back side and the execution of a smooth curved transition to the vibrating feeder in the upper part of the pitcher allows improving the separation of grain products by reducing the amplitude of grain oscillations, Caused by a rebound from the surface of the tray during the loading of the sorted material from the vibrating feeder.

  16. Viscosity and surface tension effects during multiphase flow in propped fractures

    Science.gov (United States)

    Dzikowski, Michał; Dąbrowski, Marcin

    2017-04-01

    Geological sequestration of CO2 was proposed as an important mechanism to reduce its emission into atmosphere. CO2 exhibits a higher affinity to organic matter than methane molecules and, potentially, it could be pumped and stored in shale reservoirs while enhancing late stage shale gas production. A successful analysis of CO2 sequestration in low matrix permeability rocks such as shales requires a thorough understanding of multiphase flow in stimulated rock fractures, which provide most significant pathways for fluids in such systems. Multiphase fracture flows are also of great relevance to brine, oil and gas migration in petroleum systems, water and stream circulation in geothermal reservoirs, and chemical transport of non-aqueous phase liquids in shallow hydrogeological systems, particularly in partially saturated zones. There are various physical models that describe phenomena taking place during multiphase flow through porous media. One of key aspects that need to be considered are pore-scale effects related to capillarity. Unfortunately, detailed models that describe motion and evolution of phase or component boundary require direct numerical simulations and spatial resolutions that are hard to reach when considering industrial relevant systems. Main aim of the presented work was the development of reduced 2.5D models based on Brinkman approximation of thin domain flow that would be able to capture local scale phenomena without expensive 3D simulations. Presented approach was designed specifically to tackle incompressible and immiscible systems and is based on Continuous Surface Force approach presented by Brackbill et al., implemented using Lattice Boltzmann Method. Presented approach where firstly validated against standard test cases with known classical solution and known experimental data. In the second part, we present and discuss two component, immiscible permeability data for rough and propped fracture obtained with our code for a rage of proppants

  17. Coarse-grained simulation of surface tension of perfiuorocarbons%粗粒化尺度模拟全氟烷烃的界面张力

    Institute of Scientific and Technical Information of China (English)

    杜球; 杨晓宁

    2011-01-01

    通过分子动力学模拟方法,采用构建的粗粒化模型,对全氟烷烃(C6F14和C9F20)的界面性质进行了模拟计算.模拟得到的体系界面密度分布能清楚地反映界面结构及分子分布情况.通过与不同温度下实验值进行了比较,模拟的界面张力与实验数据十分吻合,并呈现随温度升高而减小的趋势.研究表明:所构建的粗粒化模型能够准确描述全氟烷烃的表面张力性质.%The interfacial tension properties of perfluorocarbons, including C6F14 and C9F20, were simulated by using a new coarse-grained model. The obtained interface density distribution clearly displayed the structure of gas-liquid interface. The simulated surface tensions of perfluorocarbons were compared with the corresponding experimental data. Results showed that the simulated surface tensions agreed well with the experimental data. The surface tensions showed a decreasing trend with the temperature increasing. It was demonstrated that the proposed coarse-grained model could be used for further simulation.

  18. Effects of elasticity and surface tension on the spreading dynamics of a thin film under the influence of intermolecular forces

    Science.gov (United States)

    Young, Yuan-Nan; Stone, Howard

    2016-11-01

    The spreading dynamics of a thin layer of viscous Newtonian fluid between an elastic sheet and a wetting solid substrate is examined using the lubrication theory. On the wetting substrate an ultra thin film (precursor film) develops as a result of the intermolecular force between the fluid and the wetting solid substrate. Such a precursor film prevents the stress singularity associated with a moving contact line. Following the methodology by, the effects of elasticity on the macroscopic contact line structure in the quasistatic limit are elucidated by an ordinary differential equation derived from an analysis of the energy and its dissipation. Similar to the case of a regular fluid interface with surface tension (capillary spreading), the elasto-capillary thin film profile also consists of a core at the center, an ultra thin film in the far field, and a contact line region where the core film profile connects smoothly to the precursor film. For capillary spreading, the precursor film transitions monotonically to the core film. Due to the interfacial elasticity, a spatial oscillation of film height in the contact line region is found. In addition, it is found that elasticity causes the sliding motion of the thin film: the contact angle close to zero as

  19. Surface-tension-driven convection in pure liquid layers evaporating into ambient air: influence of liquid volatility

    Science.gov (United States)

    Chauvet, Fabien; Dehaeck, Sam; Colinet, Pierre

    2011-11-01

    The spontaneous surface-tension-driven convective patterns induced by evaporation of a pure liquid layer are studied experimentally. A volatile liquid layer placed in a cylindrical container is left free to evaporate into air at rest under ambient conditions. The thermal dynamics of the evaporating liquid layer is visualized using an infrared camera. Evaporation rate and liquid thickness are measured by weighting. We focus on the transition between the convective state and the conductive state appearing at a certain instant during the drying of the liquid layer. The critical Marangoni number Mac associated to this transition is estimated from evaporation rate and layer thickness measurements at this instant. The effect of the evaporation rate on Mac and kc (the critical wavenumber) has been investigated by changing the container height and, separately, the effect of the liquid volatility has been studied by using different liquids. Interestingly, it appears that Mac does not depend on the evaporation rate while it depends strongly on the liquid volatility. Given the typical uncertainties associated with liquid properties, a quite reasonable agreement is found with a ``one-sided'' linear stability analysis of this problem. Supported by ESA & BELSPO, by the EU, by ULB, and by FRS - FNRS.

  20. Application of Three-Dimensionally Printed Probe and Reservoir to Critical Micelle Concentration Determination by Microvolume Surface Tension Measurement.

    Science.gov (United States)

    Horiuchi, Shohei; Choda, Naoki; Takahashi, Haruyuki; Sato, Tomomi; Taira, Hikaru; Mukai, Kei

    2016-08-01

    It is important to determine a critical micelle concentration (CMC) of a surfactant in a protein formulation for stabilizing the protein at maximum by preventing it from interfacial denaturation. There are several techniques for CMC determination. Among them, surface tensiometry is the most common approach because this has a long history and much data at many research fields. However, large amount of sample solution is usually required for the measurement (e.g., more than 1 mL is necessary when a standard reservoir like a glass petri dish is used). This is one of the hurdles for protein formulators because only a small amount of protein could be used at the early-stage development. In this research, we tried to minimize the required amount of sample solution for surface tension measurement by developing appropriate probe and reservoir using a three-dimensional printer (3D printer). The advantages and capabilities of 3D printer are (1) to control the shape and size of the printed material precisely, (2) to change the figure freely, and (3) to prepare the prototype quickly. After the experiments and thereby the refinement of probe as well as reservoir, we found that CMCs of polysorbate 20, polysorbate 80, and poloxamer 188 in water and protein formulations could be precisely detected using a probe 0.5 mm in diameter and small reservoir with a pocket of 7.5 mm in diameter/0.25 mm in depth which were made by a 3D printer. Furthermore, the required sample solution per each measurement could be reduced to 80 μL, which means more than 90% reduction against a standard reservoir.

  1. Surface Tension of Molten Nickel-Tungsten Alloy%熔融Ni-W合金的表面张力研究

    Institute of Scientific and Technical Information of China (English)

    肖锋; 刘兰霄; 杨仁辉; 傅亚; 方亮; 赵红凯

    2008-01-01

    Surface tension of molten Ni-(5~10)W (mass fraction,%)alloys was measured at the temperature range of 1773~1873 K using an improved sessile drop method with an alumina substrate in an Ar+3%H2 atmosphere.The surface tension of molten Ni-W alloys decreases with increasing of temperature.On the basis of experimental data,the surface tension of molten Ni-W alloys was also theoretically deduced both as functions of concentration and temperature using a model of Butler's equation.The surface segregation in Ni-W system was calculated.The measured results agree well with a model for the surface tension.The surface concentration oftungsten is lower than that in bulk.%采用改进静滴法测定了1773~1873 K温度范围内熔融Ni-(5~10)W(质量分数,%)合金在Al2O3基板上于Ar+3%H2气氛下的表面张力数据.熔融Ni-W合金的表面张力随着温度的升高而降低.在此基础上采用Butler模型推导了表面张力随温度与浓度的变化情况,计算了合金体系中元素的偏聚情况.表面张力的计算结果与测量值的符合度较高.W在合金表面的浓度低于体相浓度.

  2. 修正表面张力算法的SPH方法及其实现%Smoothed Particle Hydrodynamics Method with Modified Surface Tension and Its Implementation

    Institute of Scientific and Technical Information of China (English)

    强洪夫; 陈福振; 高巍然

    2011-01-01

    Modified equations for surface tension are derived by modifying normal and curvature with corrected smoothed particle method (CSPM). It is based on smoothed particle hydrodynamics (SPH) method with surface tension proposed by Morris. Both Morris and our method are tested via a semicircular problem. Factors that affect accuracy are investigated including surface definition, normal and curvature calculation. Smoothed length in curvature calculation is also confirmed reasonable. Furthermore, formation of a liquid drop with initial square shape under surface tension is simulated. Compared with Morris method and grid-based volume of fluid method,it is proved that the accuracy of our method is higher and particle distribution is more homogeneous. Finally, coalescence process of two oil drops in water under surface tension is simulated.%在Morris提出的表面张力SPH方法基础上,通过引入CSPM方法对边界法向的计算和曲率的计算进行修正,得到表面张力修正方程组;通过半圆形算例测试方法和Morris方法在边界定位、法向计算和曲率计算等影响表面张力关键因素的求解精度,研究曲率计算中应采用的光滑长度值.模拟初始方形液滴在表面张力作用下的自然变化过程,并与Morris方法及VOF有限体积法进行对比,表明方法精度较高,稳定性较好.最后,模拟水溶液中两个油滴的互溶过程.

  3. Carboxymethylated lignins with low surface tension toward low viscosity and highly stable emulsions of crude bitumen and refined oils.

    Science.gov (United States)

    Li, Shuai; Ogunkoya, Dolanimi; Fang, Tiegang; Willoughby, Julie; Rojas, Orlando J

    2016-11-15

    Kraft and organosolv lignins were subjected to carboxymethylation to produce fractions that were soluble in water, displayed a minimum surface tension as low as 34mN/m (25°C) and a critical aggregation concentration of ∼1.5wt%. The carboxymethylated lignins (CML), which were characterized in terms of their degree of substitution ((31)P NMR), elemental composition, and molecular weight (GPC), were found suitable in the formulation of emulsions with bitumens of ultra-high viscosity, such as those from the Canadian oil sands. Remarkably, the interfacial features of the CML enabled fuel emulsions that were synthesized in a very broad range of internal phase content (30-70%). Cryo-replica transmission electron microscopy, which was used here the first time to assess the morphology of the lignin-based emulsions, revealed the droplets of the emulsion stabilized with the modified lignin. The observed drop size (diametersoperations for power generation, which also take advantage of the high heating value of the emulsion components. The ability of CML to stabilize emulsions and to contribute in their combustion was tested with light fuels (kerosene, diesel, and jet fuel) after formulation of high internal phase systems (70% oil) that enabled operation of a fuel engine. A significant finding is that under certain conditions and compared to the respective pure fuel, combustion of the O/W emulsions stabilized by CML presented lower NOx and CO emissions and maintained a relatively high combustion efficiency. The results highlight the possibilities in high volume application for lignin biomacromolecules.

  4. Nanomechanical properties of lipid bilayer: Asymmetric modulation of lateral pressure and surface tension due to protein insertion in one leaflet of a bilayer

    Science.gov (United States)

    Maftouni, Negin; Amininasab, Mehriar; Ejtehadi, Mohammad Reza; Kowsari, Farshad; Dastvan, Reza

    2013-02-01

    The lipid membranes of living cells form an integral part of biological systems, and the mechanical properties of these membranes play an important role in biophysical investigations. One interesting problem to be evaluated is the effect of protein insertion in one leaflet of a bilayer on the physical properties of lipid membrane. In the present study, an all atom (fine-grained) molecular dynamics simulation is used to investigate the binding of cytotoxin A3 (CTX A3), a cytotoxin from snake venom, to a phosphatidylcholine lipid bilayer. Then, a 5-microsecond coarse-grained molecular dynamics simulation is carried out to compute the pressure tensor, lateral pressure, surface tension, and first moment of lateral pressure in each monolayer. Our simulations reveal that the insertion of CTX A3 into one monolayer results in an asymmetrical change in the lateral pressure and corresponding spatial distribution of surface tension of the individual bilayer leaflets. The relative variation in the surface tension of the two monolayers as a result of a change in the contribution of the various intermolecular forces may potentially be expressed morphologically.

  5. Densities, viscosities, refractive indices, and surface tensions for binary and ternary mixtures of 2-propanol, tetrahydropyran, and 2,2,4-trimethylpentane

    Energy Technology Data Exchange (ETDEWEB)

    Kao, Y.-C. [Department of Applied Chemistry, Providence University, Shalu 43301, Taiwan (China); Tu, C.-H., E-mail: chtu@pu.edu.t [Department of Applied Chemistry, Providence University, Shalu 43301, Taiwan (China)

    2011-02-15

    Densities, viscosities, refractive indices, and surface tensions of the ternary system (2-propanol + tetrahydropyran + 2,2,4-trimethylpentane) at T = 303.15 K and its constituent binary systems (2-propanol + tetrahydropyran, 2-propanol + 2,2,4-trimethylpentane, and tetrahydropyran + 2,2,4-trimethylpentane) at T = (293.15, 303.15, 313.15, and 323.15) K were measured at atmospheric pressure. Densities were determined using a vibrating-tube densimeter. Viscosities were measured with an automatic microviscometer based on the rolling-ball principle. Refractive indexes were measured using a digital Abbe-type refractometer. Surface tensions were determined by the Wilhelmy-plate method. From these data, excess molar volumes, deviations in viscosity, deviations in refractive index, and deviations in surface tension were calculated. The results for the binary and ternary systems were fitted to the Redlich-Kister equation and the variable-degree polynomials in terms of compositions, respectively. The experimental and calculated quantities are used to study the nature of mixing behaviour between mixture components.

  6. Free Energies of Solvation with Surface, Volume, and Local Electrostatic Effects and Atomic Surface Tensions to Represent the First Solvation Shell.

    Science.gov (United States)

    Liu, Junjun; Kelly, Casey P; Goren, Alan C; Marenich, Aleksandr V; Cramer, Christopher J; Truhlar, Donald G; Zhan, Chang-Guo

    2010-03-04

    Building on the SVPE (surface and volume polarization for electrostatics) model for electrostatic contributions to the free energy of solvation with explicit consideration of both surface and volume polarization effects, on the SMx approach to including first-solvation-shell contributions, and on the linear relationship between the electric field and short-range electrostatic contributions found by Chipman, we have developed a new method for computing absolute aqueous solvation free energies by combining the SVPE method with semiempirical terms that account for effects beyond bulk electrostatics. The new method is called SMVLE, and the elements it contains are denoted by SVPE-CDSL where SVPE denotes accounting for bulk electrostatic interactions between solute and solvent with both surface and volume contributions, CDS denotes the inclusion of solvent cavitation, changes in dispersion energy, and possible changes in local solvent structure by a semiempirical term utilizing geometry-dependent atomic surface tensions as implemented in SMx models, and L represents the local electrostatic effect derived from the outward-directed normal electric field on the cavity surface. The semiempirical CDS and L terms together represent the deviation of short-range contributions to the free energy of solvation from those accounted for by the SVPE term based on the bulk solvent dielectric constant. A solute training set containing a broad range of molecules used previously in the development of SM6 is used here for SMVLE model calibration. The aqueous solvation free energies predicted by the parameterized SMVLE model correlate exceedingly well with experimental values. The square of the correlation coefficient is 0.9949 and the slope is 1.0079. Comparison of the final SMVLE model against the earlier SMx solvation model shows that the parameterized SMVLE model not only yields good accuracy for neutrals but also significantly increases the accuracy for ions, making it the best

  7. Measurement and Analyses of Molten Nickel-Cobalt Alloy Surface Tension%熔融Ni-Co合金表面张力的测量与分析

    Institute of Scientific and Technical Information of China (English)

    肖锋; 刘兰霄; 方亮; 杨仁辉; 傅亚; 赵红凯

    2008-01-01

    Ni-Co super-alloy is widely used in high temperature and corrosive environments such as gas turbine engines and heat exchangers. The surface tensions of molten Ni and Ni-Co (5 and 10 mass fraction) alloys were measured at the temperature range of 1773~1873 K using an improved sessile drop method with an alumina substrate in an Ar+3%H2 atmosphere. The surface tensions of molten Ni and Ni-Co (5 and 10 mass fiaction) alloys decrease with increasing of temperature. On the basis of experimental data, the surface tension was also theoretically deduced both as functions of concentration and temperature using a model of Butler' equation. The alloy element segregation in this system was calculated. Cobalt concentration on surface of alloys is lower than that in bulk.%Ni-Co高温合金广泛用于生产燃气涡轮机叶片和热交换器等工作于高温和腐蚀环境的零部件,采用改良静滴法测定了1773~1873K温度范围内熔融Ni,Ni-(5~10)%Co合金在Al2O3基板上Ar+3%H2气氛下的表面张力.熔融Ni,Ni-(5~10)%Co合金的表面张力随着温度的升高而降低.在此基础上采用Butler模型推导了表面张力随温度与浓度的变化,计算了合金体系中元素的偏聚.结果表明,Co在合金表面的浓度低于在体相的浓度.

  8. Surface Tension and Viscosity of the Ni-Based Superalloys LEK94 and CMSX-10 Measured by the Oscillating Drop Method on Board a Parabolic Flight

    Science.gov (United States)

    Wunderlich, Rainer K.; Fecht, Hans-Jörg; Lohöfer, Georg

    2017-02-01

    The surface tension and viscosity of the Ni-based superalloys LEK94 and CMSX-10 were measured by the oscillating drop method in a containerless electromagnetic processing device on board a parabolic flight airplane. Surface oscillations were recorded by 150 and 200 Hz frame rate digital cameras positioned in two perpendicular directions and by the inductive coupling between the oscillating sample surface and the oscillating circuit of the radio frequency heating and positioning generator. The surface tension as a function of temperature of LEK94 and CMSX-10 was obtained as σ( T) = 1.73 - 4.51 × 10-4 [ T—1656 K (1383 °C)] Nm-1 and σ( T) = 1.71 - 5.80 × 10-4 [( T—1683 K (1410 °C)] Nm-1, respectively. The viscosity at the liquidus temperatures as 9.8 and 7.8 mPa.s, respectively. In addition, some basic thermophysical properties such as solidus and liquidus temperatures, densities at room temperature, and thermal expansion in the solid phase are reported.

  9. Testing the Influence of Surface Tension and Finite Width of QGP Bags on the QCD Matter EOS Properties at NICA Energies

    CERN Document Server

    Bugaev, Kyrill A

    2009-01-01

    Here I give some strong arguments that the central issues for theoretical studies of the (tri)critical endpoint of the QCD phase diagram are the surface tension of large/heavy QGP bags and their medium dependent width. Then I discuss three major directions to further develop the realistic exactly solvable statistical models which simultaneously are able to describe the 1-st order deconfinement phase transition, the 2-nd order one and the cross-over. Also I analyze the most necessary projects that have to be studied in order to formulate the reliable and convincing signals of the mixed phase formation at NICA energies.

  10. Fluid accumulation in thin-film fl ows driven by surface tension and gravity (I): Rigorous analysis of a drainage equation

    CERN Document Server

    Cuesta, C M

    2011-01-01

    We derive a boundary layer equation describing accumulation regions within a thin-film approximation framework where gravity and surface tension balance. As part of the analysis of this problem we investigate in detail and rigorously the 'drainage' equation (phi"'+1)phi^3=1. In particular, we prove that all solutions that do not tend to 1 as the independent variable goes to infinity are oscillatory, and that they oscillate in a very specific way. This result and the method of proof will be used in the analysis of solutions of the afore mentioned boundary layer problem.

  11. Secondary organic material formed by methylglyoxal in aqueous aerosol mimics – Part 1: Surface tension depression and light-absorbing products

    Directory of Open Access Journals (Sweden)

    V. F. McNeill

    2009-07-01

    Full Text Available We show that methylglyoxal forms light-absorbing secondary organic material in aqueous ammonium sulfate and ammonium nitrate solutions mimicking tropospheric aerosol particles. The light-absorbing products form on the order of minutes, and solution composition continues to change over several days. The results suggest an aldol condensation pathway involving the participation of the ammonium ion. Aqueous solutions of methylglyoxal, with and without inorganic salts, exhibit surface tension depression. Methylglyoxal uptake could potentially change the optical properties, climate effects, and heterogeneous chemistry of the seed aerosol over its lifetime.

  12. Effect of surface tension and coefficient of thermal expansion in 30 nm scale nanoimprinting with two flexible polymer molds.

    Science.gov (United States)

    Kim, Jae Kwan; Cho, Hye Sung; Jung, Ho-Sup; Lim, Kipil; Kim, Ki-Bum; Choi, Dae-Geun; Jeong, Jun-Ho; Suh, Kahp-Yang

    2012-06-15

    We report on nanoimprinting of polymer thin films at 30 nm scale resolution using two types of ultraviolet (UV)-curable, flexible polymer molds: perfluoropolyether (PFPE) and polyurethane acrylate (PUA). It was found that the quality of nanopatterning at the 30 nm scale is largely determined by the combined effects of surface tension and the coefficient of thermal expansion of the polymer mold. In particular, the polar component of surface tension may play a critical role in clean release of the mold, as evidenced by much reduced delamination or broken structures for the less polarized PFPE mold when patterning a relatively hydrophilic PMMA film. In contrast, such problems were not notably observed with a relatively hydrophobic PS film for both polymer molds. In addition, the demolding characteristic was also influenced by the coefficient of thermal expansion so that no delamination or uniformity problems were observed when patterning a UV-curable polymer film at room temperature. These results suggest that a proper polymeric mold material needs to be chosen for patterning polymer films under different surface properties and processing conditions, providing insights into how a clean demolding characteristic can be obtained at 30 nm scale nanopatterning.

  13. 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.

  14. 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.

  15. Tension Structure

    Science.gov (United States)

    1978-01-01

    The fabric structure pictured is the Campus Center of La Verne College, La Verne, California. Unlike the facilities shown on the preceding pages, it is not air-supported. It is a "tension structure," its multi-coned fabric membrane supported by a network of cables attached to steel columns which function like circus tent poles. The spider-web in the accompanying photo is a computer graph of the tension pattern. The designers, Geiger-Berger Associates PC, of New York City, conducted lengthy computer analysis to determine the the best placement of columns and cables. The firm also served as structural engineering consultant on the Pontiac Silverdome and a number of other large fabric structures. Built by Birdair Structures, Inc., Buffalo, New York, the La Verne Campus Center was the first permanent facility in the United States enclosed by the space-spinoff fabric made of Owens-Corning Beta fiber glass coated with Du Pont Teflon TFE. The flexible design permits rearrangement of the interior to accommodate athletic events, student activities, theatrical productions and other recreational programs. Use of fabric covering reduced building cost 30 percent below conventional construction.

  16. Adsorção e propriedades de volume de misturas binárias água álcool: um experimento didático com base em medidas de tensão superficial An undergraduate experiment in physical chemistry: adsorption and bulk properties of alcohol-water mixtures based on surface tension measurements

    OpenAIRE

    Michelly C. dos Santos; Moraes,Aline P.; Lemes,Maykon A.; Lima,Emília C. D.; Oliveira,Anselmo E. de

    2010-01-01

    An undergraduate physical chemistry experiment based on the drop counting method for surface tension measurements is proposed to demonstrate adsorption isotherms of binary aqueous solutions of ethanol, n-propanol, and n-butanol. Excess surface is obtained by the derivative of surface tension taken with respect to alcohol activity, after this activity calculation using van Laar equation. Laboratory class contents are surface tension, excess surface, percolation of hydrogen bonds, micelle, acti...

  17. Adsorção e propriedades de volume de misturas binárias água álcool: um experimento didático com base em medidas de tensão superficial An undergraduate experiment in physical chemistry: adsorption and bulk properties of alcohol-water mixtures based on surface tension measurements

    Directory of Open Access Journals (Sweden)

    Michelly C. dos Santos

    2010-01-01

    Full Text Available An undergraduate physical chemistry experiment based on the drop counting method for surface tension measurements is proposed to demonstrate adsorption isotherms of binary aqueous solutions of ethanol, n-propanol, and n-butanol. Excess surface is obtained by the derivative of surface tension taken with respect to alcohol activity, after this activity calculation using van Laar equation. Laboratory class contents are surface tension, excess surface, percolation of hydrogen bonds, micelle, activity, and ideal solution.

  18. Wettability of Molten Aluminum-Silicon Alloys on Graphite and Surface Tension of Those Alloys at 1273 K (1000 °C)

    Science.gov (United States)

    Mao, Weiji; Noji, Takayasu; Teshima, Kenichiro; Shinozaki, Nobuya

    2016-06-01

    The wettability of molten aluminum-silicon alloys with silicon contents of 0, 6, 10, and 20 mass pct on graphite substrates by changing the placing sequence of aluminum and silicon and the surface tension of those alloys were investigated at 1273 K (1000 °C) using the sessile drop method under vacuum. The results showed that the wetting was not affected by changing the placing sequence of the Al-Si alloys on the graphite substrates. The wettability was not improved significantly upon increasing the Si content from 0 to 10 mass pct, whereas a notable decrease of 22 deg in the contact angle was observed when increasing the Si content from 10 to 20 mass pct. This was attributed to the transformation of the interfacial reaction product from Al4C3 into SiC, provided the addition of Si to Al was sufficient. It was verified that the liquid Al can wet the SiC substrate very well in nature, which might explain why the occurrence of SiC would improve the wettability of the Al-20 mass pct Si alloy on the graphite substrate. The results also showed that the surface tension values of the molten Al-Si alloys decreased monotonously with an increase in Si content, being 875, 801, 770, and 744 mN/m for molten Al, Al-6 mass pct Si, Al-10 mass pct Si, and Al-20 mass pct Si alloys, respectively.

  19. The Cloud Condensation Nuclei (CCN properties of 2-methyltetrols and C3–C6 polyols from osmolality and surface tension measurements

    Directory of Open Access Journals (Sweden)

    S. Ekström

    2008-09-01

    Full Text Available A significant fraction of the organic material in aerosols is made of highly soluble compounds such as sugars (mono- and polysaccharides and polyols, including the 2-methyltetrols, methylerythritol and methyltreitol. The high solubility of these compounds has brought the question of their potentially high CCN efficiency. For the 2-methyltetrols, this would have important implications for cloud formation at global scale because they are thought to be produced by the atmospheric oxidation of isoprene. To investigate this question, the complete Köhler curves for C3–C6 polyols and the 2-methyltetrols have been determined experimentally from osmolality and surface tension measurements. Contrary to what expected, none of these compounds displayed a critical supersaturation lower than those of inorganic salts or organic acids. Their Raoult terms show that this limited CCN efficiency is due to their absence of dissociation in water, this in spite of slight surface-tension effects for the 2-methyltetrols. Thus, compounds such as sugars and polyols would not contribute more to cloud formation in the atmosphere than any other organic compounds studied so far. In particular, the presence of 2-methyltetrols in aerosols would not particularly enhance cloud formation in the atmosphere, contrary to what has been suggested.

  20. Horizon Thermodynamics and Gravitational Tension

    CERN Document Server

    Widom, A; Srivastava, Y N

    2016-01-01

    We consider the thermodynamics of a horizon surface from the viewpoint of the vacuum tension $\\tau =(c^4/4G )$. Numerically, $\\tau \\approx 3.026\\times 10^{43}$ Newton. In order of magnitude, this is the tension that has been proposed for microscopic string models of gravity. However, after decades of hard work on string theory models of gravity, there is no firm scientific evidence that such models of gravity apply empirically. Our purpose is thereby to discuss the gravitational tension in terms of the conventional Einstein general theory of relativity that apparently does explain much and maybe all of presently known experimental gravity data. The central result is that matter on the horizon surface is bound by the entropy-area law by tension in the closely analogous sense that the Wilson action-area law also describes a surface confinement.

  1. Thin concentrator photovoltaic module with micro-solar cells which are mounted by self-align method using surface tension of melted solder

    Science.gov (United States)

    Hayashi, Nobuhiko; Terauchi, Masaharu; Aya, Youichirou; Kanayama, Shutetsu; Nishitani, Hikaru; Nakagawa, Tohru; Takase, Michihiko

    2017-09-01

    We are developing a thin and lightweight CPV module using small size lens system made from poly methyl methacrylate (PMMA) with a short focal length and micro-solar cells to decrease the transporting and the installing costs of CPV systems. In order to achieve high conversion efficiency in CPV modules using micro-solar cells, the micro-solar cells need to be mounted accurately to the irradiated region of the concentrated sunlight. In this study, we have successfully developed self-align method thanks to the surface tension of the melted solder even utilizing commercially available surface-mounting technology (SMT). Solar cells were self-aligned to the specified positions of the circuit board by this self-align method with accuracy within ±10 µm. We actually fabricated CPV modules using this self-align method and demonstrated high conversion efficiency of our CPV module.

  2. A novel weighted density functional theory for adsorption, fluid-solid interfacial tension, and disjoining properties of simple liquid films on planar solid surfaces.

    Science.gov (United States)

    Yu, Yang-Xin

    2009-07-14

    A novel weighted density functional theory (WDFT) for an inhomogeneous 12-6 Lennard-Jones fluid is proposed based on the modified fundamental measure theory for repulsive contribution, the mean-field approximation for attractive contribution, and the first-order mean-spherical approximation with a weighted density for correlation contribution. Extensive comparisons of the theoretical results with molecular simulation and experimental data indicate that the new WDFT yields accurate density profiles, adsorption isotherms, fluid-solid interfacial tensions, as well as disjoining potentials and pressures of simple gases such as argon, nitrogen, methane, ethane, and neon confined in slitlike pores or near graphitic solid surfaces. The present WDFT performs better than the nonlocal density functional theory, which is frequently used in the study of adsorption on porous materials. Since the proposed theory possesses a good dimensional crossover and is able to correctly reduce to two-dimensional case, it performs very well even in very narrow pores. In addition, the present WDFT reproduces very well the supercritical fluid-solid interfacial tensions, whereas the theory of Sweatman underestimates them at high bulk densities. The present WDFT predicts that the increase in the fluid-wall attraction may change the sign of the interfacial tension and hence may make the wall from "phobic" to "philic" with respect to the fluid. The new WDFT is computationally as simple and efficient as the mean-field theory and avoids the second-order direct correlation function as an input. It provides a universal way to construct the excess Helmholtz free-energy functional for inhomogeneous fluids such as Yukawa, square-well, and Sutherland fluids.

  3. Spontaneous Pattern Formation Induced by Bénard-Marangoni Convection for Sol-Gel-Derived Titania Dip-Coating Films: Effect of Co-solvents with a High Surface Tension and Low Volatility.

    Science.gov (United States)

    Uchiyama, Hiroaki; Matsui, Tadayuki; Kozuka, Hiromitsu

    2015-11-17

    Evaporation-driven surface tension gradient in the liquid layer often causes the convective flow, i.e., Bénard-Marangoni convection, resulting in the formation of cell-like patterns on the surface. Here, we prepared sol-gel-derived titania films from Ti(OC3H7(i))4 solutions by dip coating and discussed the effect of the addition of co-solvents with a high surface tension and low volatility on the spontaneous pattern formation induced by Bénard-Marangoni convection. Propylene glycol (PG, with a surface tension of 38.6 mN m(-1)) and dipropylene glycol (DPG, with a surface tension of 33.9 mN m(-1)) were added to the coating solutions containing 2-propanol (2-Pr, with a surface tension of 22.9 mN m(-1)) for controlling the evaporation-driven surface tension gradient in the coating layer on a substrate. During dip coating at a substrate withdrawal speed of 50 cm min(-1) in a thermostatic oven at 60 °C, linearly arranged cell-like patterns on a micrometer scale were spontaneously formed on the titania gel films, irrespective of the composition of coating solutions. Such surface patterns remained even after the heat treatment at 200 and 600 °C, where the densification and crystallization of the titania films progressed. The width and height of the cell-like patterns increased with increasing PG and DPG contents in the coating solutions, where the addition of PG resulted in the formation of cells with a larger height than DPG.

  4. Universal solvation model based on solute electron density and on a continuum model of the solvent defined by the bulk dielectric constant and atomic surface tensions.

    Science.gov (United States)

    Marenich, Aleksandr V; Cramer, Christopher J; Truhlar, Donald G

    2009-05-07

    We present a new continuum solvation model based on the quantum mechanical charge density of a solute molecule interacting with a continuum description of the solvent. The model is called SMD, where the "D" stands for "density" to denote that the full solute electron density is used without defining partial atomic charges. "Continuum" denotes that the solvent is not represented explicitly but rather as a dielectric medium with surface tension at the solute-solvent boundary. SMD is a universal solvation model, where "universal" denotes its applicability to any charged or uncharged solute in any solvent or liquid medium for which a few key descriptors are known (in particular, dielectric constant, refractive index, bulk surface tension, and acidity and basicity parameters). The model separates the observable solvation free energy into two main components. The first component is the bulk electrostatic contribution arising from a self-consistent reaction field treatment that involves the solution of the nonhomogeneous Poisson equation for electrostatics in terms of the integral-equation-formalism polarizable continuum model (IEF-PCM). The cavities for the bulk electrostatic calculation are defined by superpositions of nuclear-centered spheres. The second component is called the cavity-dispersion-solvent-structure term and is the contribution arising from short-range interactions between the solute and solvent molecules in the first solvation shell. This contribution is a sum of terms that are proportional (with geometry-dependent proportionality constants called atomic surface tensions) to the solvent-accessible surface areas of the individual atoms of the solute. The SMD model has been parametrized with a training set of 2821 solvation data including 112 aqueous ionic solvation free energies, 220 solvation free energies for 166 ions in acetonitrile, methanol, and dimethyl sulfoxide, 2346 solvation free energies for 318 neutral solutes in 91 solvents (90 nonaqueous

  5. Study on Surface Dynamic Behavior and Critical Surface Tension of Coal with Different Metamorphic Grades%不同变质程度煤表面动态行为与临界表面张力的研究

    Institute of Scientific and Technical Information of China (English)

    刘谦; 郭玉森; 赖永明; 林璐瑶

    2015-01-01

    为研究不同变质程度煤表面动态行为和临界表面张力,利用悬滴法恒温27 ℃测试不同浓度下的烷基糖苷( APG)溶液表面张力,以及利用躺滴法动态连续跟踪测量模式研究不同浓度下的APG溶液在煤表面接触角随时间的变化情况. 研究结果表明:水在煤表面形成接触角较大,且接触角变化不明显;随着APG溶液浓度的增大,溶液在煤表面形成的接触角变小,同时接触角的变化幅度也在增大,当APG溶液浓度超过临界胶束浓度时,接触角进一步减小,但变化幅度减小;接触角余弦值与临界表面张力的相关性显著,且呈负相关关系;随着煤样变质程度的提高,临界表面张力先减小后增大.%In order to study the dynamic behavior and critical surface tension of coal with different metamorphic grades, the pendant drop method was used to test the surface tension of alkyl glucoside ( APG ) solution in different concentrations at the constant temperature of 27 ℃, and the dynamic continuous tracking measurement mode of the sessile drop method was used to study the change of the surface contact angle of APG solution in different concentrations with time. The results showed that the contact angle of water on coal surface was relative large, but its change was not obvious;with the increase of APG concentration, the contact angle of APG on coal surface decreased while the change magnitude of the contact angle increased, when APG concentration exceeded the critical micelle concentration, the contact angle further reduced, so did its change magnitude; the cosine value of the contact angle was significantly correlated with the critical surface tension, they were in a negative correlation;with the increase of the metamorphic grade of coal, the critical surface tension first decreased and then increased.

  6. Volumetric properties, viscosities, refractive indices and surface tensions for (dimethylpropanolamine (DMPA) + water) mixtures from 298.15 K to 343.15 K

    Energy Technology Data Exchange (ETDEWEB)

    Narayanaswamy, Kamal; Rayer, Aravind V.; Kadiwala, Salim [International Test Center for CO2 Capture, Faculty of Engineering and Applied Science, University of Regina, Regina, Saskatchewan S4S 0A2 (Canada); Henni, Amr, E-mail: amr.henni@uregina.ca [International Test Center for CO2 Capture, Faculty of Engineering and Applied Science, University of Regina, Regina, Saskatchewan S4S 0A2 (Canada)

    2012-09-10

    Highlights: Black-Right-Pointing-Pointer {rho}, {eta}, n{sub D}, and {gamma} of aqueous dimethylpropanolamine solutions are reported. Black-Right-Pointing-Pointer Change of H{sub 2}O structure in amines was explained using thermodynamic transfer functions. Black-Right-Pointing-Pointer Possible complex formation at mole fraction x = 0.3. - Abstract: This paper reports the experimental data for the densities and viscosities at six temperatures (298.15-343.15) K, refractive indices at nine temperatures (293.15-333.15) K, and surface tensions at seven temperatures (298.15-333.15) K for aqueous solutions of dimethylpropanolamine (DMPA). Excess properties derived from the experimental results were discussed in terms of changes in molecular interactions in the mixtures. The derived deviations of the properties were regressed with the Redlich-Kister equation. The derived thermodynamic properties were then compared with those of other tertiary amines available in the literature.

  7. Improvement of the free-surface tension model in shallow water basin by using in-situ bottom-friction measurements

    Science.gov (United States)

    Alekseenko, Elena; Kuznetsov, Konstantin; Roux, Bernard

    2016-04-01

    Wind stress on the free surface is the main driving force behind the circulation of the upper part of the ocean, which in hydrodynamic models are usually defined in terms of the coefficient of surface tension (Zhang et al., 2009, Davies et al., 2003). Moreover, wave motion impacts local currents and changes sea level, impacts the transport and the stratification of the entire water column. Influence of surface waves at the bottom currents is particularly pronounced in the shallow coastal systems. However, existing methods of parameterization of the surface tension have significant limits, especially in strong wind waves (Young et al., 2001, Jones et al., 2004) due to the difficulties of measuring the characteristics of surface waves in stormy conditions. Thus, the formula for calculating the coefficient of surface tension in our day is the actual problem in modeling fluid dynamics, particularly in the context of strong surface waves. In the hydrodynamic models usually a coefficient of surface tension is calculated once at the beginning of computation as a constant that depends on the averaged wind waves characteristic. Usually cases of strongly nonlinear wind waves are not taken into account, what significantly reduces the accuracy of the calculation of the flow structures and further calculation of the other processes in water basins, such as the spread of suspended matter and pollutants. Thus, wave motion influencing the pressure on the free surface and at the bottom must be considered in hydrodynamic models particularly in shallow coastal systems. A method of reconstruction of a free-surface drag coefficient based on the measured in-situ bottom pressure fluctuations is developed and applied in a three-dimensional hydrodynamic model MARS3D, developed by the French laboratory of IFREMER (IFREMER - French Research Institute for Marine Dynamics). MARS3D solves the Navier-Stokes equations for incompressible fluid in the Boussinesq approximation and with the

  8. Adsorção e propriedades de volume de misturas binárias água álcool: um experimento didático com base em medidas de tensão superficial An undergraduate experiment in physical chemistry: adsorption and bulk properties of alcohol-water mixtures based on surface tension measurements

    National Research Council Canada - National Science Library

    Michelly C. dos Santos; Aline P. Moraes; Maykon A. Lemes; Emília C. D. Lima; Anselmo E. de Oliveira

    2010-01-01

    An undergraduate physical chemistry experiment based on the drop counting method for surface tension measurements is proposed to demonstrate adsorption isotherms of binary aqueous solutions of ethanol...

  9. Surface Tension of Binary Mixtures Including Polar Components Modeled by the Density Gradient Theory Combined with the PC-SAFT Equation of State

    Science.gov (United States)

    Vinš, Václav; Planková, Barbora; Hrubý, Jan

    2013-05-01

    In this study, the Cahn-Hilliard density gradient theory (GT) is used for predicting the surface tension of various binary mixtures at relatively wide temperature ranges and for testing the application of the GT for predictions of homogeneous nucleation. The GT was combined with two physically based equations of state (EoS), namely the perturbed-chain (PC) statistical associating fluid theory (SAFT) and its modification for polar substances the perturbed-chain polar (PCP) SAFT. The GT applied to the planar phase interface was employed to predict the interfacial tension for various quadrupolar (CO2 and benzene) and dipolar (difluoromethane, i.e., R32; pentafluoroethane, i.e., R125; and 1,1,1,2-tetrafluoroethane, i.e., R134a) substances and for five binary mixtures including polar components ( n-decane + CO2, benzene + CO2, R32 + R125, R32 + R134a, R134a + R125). The PCP-SAFT EoS combined with the GT provides more accurate results for both the quadrupolar and dipolar substances than the original PC-SAFT EoS. Besides the planar phase interface, the GT was also applied to the spherical phase interface simulating a critical cluster occurring in homogeneous nucleation of droplets. Carbon dioxide was considered, because it has a relatively high quadrupole moment and because of its relevance to natural gas processing. Application of the PCP-SAFT EoS provides a significant improvement compared to the PC-SAFT EoS, and it is clearly superior to the classical cubic Peng-Robinson EoS, which is still used for modeling droplet nucleation.

  10. Hygroscopic properties of Amazonian biomass burning and European background HULIS and investigation of their effects on surface tension with two models linking H-TDMA to CCNC data

    Directory of Open Access Journals (Sweden)

    E. O. Fors

    2010-06-01

    Full Text Available HUmic-LIke Substances (HULIS have been identified as major contributors to the organic carbon in atmospheric aerosol. The term "HULIS" is used to describe the organic material found in aerosol particles that resembles the humic organic material in rivers and sea water and in soils. In this study, two sets of filter samples from atmospheric aerosols were collected at different sites. One set of samples was collected at the K-puszta rural site in Hungary, about 80 km SE of Budapest, and a second was collected at a site in Rondônia, Amazonia, Brazil, during the Large-Scale Biosphere-Atmosphere Experiment in Amazonia – Smoke Aerosols, Clouds, Rainfall and Climate (LBA-SMOCC biomass burning season experiment. HULIS were extracted from the samples and their hygroscopic properties were studied using a Hygroscopicity Tandem Differential Mobility Analyzer (H-TDMA at relative humidity (RH <100%, and a cloud condensation nucleus counter (CCNC at RH >100%. The H-TDMA measurements were carried out at a dry diameter of 100 nm and for RH ranging from 30 to 98%. At 90% RH the HULIS samples showed diameter growth factors between 1.04 and 1.07, reaching values of 1.4 at 98% RH. The cloud nucleating properties of the two sets of aerosol samples were analysed using two types of thermal static cloud condensation nucleus counters. Two different parameterization models were applied to investigate the potential effect of HULIS surface activity, both yielding similar results. For the K-puszta winter HULIS sample, the surface tension at the point of activation was estimated to be lowered by between 34% (47.7 mN/m and 31% (50.3 mN/m for dry sizes between 50 and 120 nm in comparison to pure water. A moderate lowering was also observed for the entire water soluble aerosol sample, including both organic and inorganic compounds, where the surface tension was decreased by between 2% (71.2 mN/m and 13% (63.3 mN/m.

  11. 铋含量对铅铋合金表面张力的影响分析%Influence of Bismuth Content on Surface Tension of Lead-bismuth Alloy

    Institute of Scientific and Technical Information of China (English)

    王龙; 徐敬尧; 徐刚; 刘少军; 黄群英

    2013-01-01

    Liquid lead-bismuth alloy has been considered as the potential candidates for the liquid spallation targets and the coolant of accelerator driven sub-critical system (ADS ) . Surface tension is one of the important thermal and physical properties parameters of lead-bismuth alloy , and temperature and chemical composition are important influence factors of surface tension . In this paper , the surface tension of liquid lead-bismuth alloy was measured by sessile drop (SD ) method . The results indicate that the surface tension of lead-bismuth alloy firstly increases and then decreases with the increase of the test temperature ,and the surface tension for low test temperature is significantly small .At the same temperature ,the surface tension of lead-bismuth alloy decreases with the increase of bismuth content , and segregation of bismuth onto the surface of molten lead-bismuth alloy is a key factor leading to the smaller surface tension .T he results of this study provide basic reference for composition optimization of lead-bismuth alloy ,w hich is of great significance for the development of spallation targets and the coolant materials of accelerated driven sub-critical system .%液态铅铋合金是加速器驱动的次临界系统(ADS )中散裂靶兼冷却剂的主要候选材料。表面张力是液态铅铋合金的重要热物性参数之一,而温度和化学组成是影响表面张力的关键因素。本文采用静滴法测量了5种不同成分铅铋合金的表面张力。实验结果显示:在测试温度范围内,铅铋合金的表面张力均随温度的升高先增大后减小,且在低温区表面张力非常小;相同温度下,铅铋合金的表面张力随Bi含量的增大逐渐降低,其中Bi的表面偏聚是导致其变小的重要因素之一。本研究结果为铅铋合金的成分优化提供了基本参考,对发展ADS散裂靶和冷却剂材料具有重要意义。

  12. Correlation of Oil-Water and Air-Water Contact Angles of Diverse Silanized Surfaces and Relationship to Fluid Interfacial Tensions

    Energy Technology Data Exchange (ETDEWEB)

    Grate, Jay W.; Dehoff, Karl J.; Warner, Marvin G.; Pittman, Jonathan W.; Wietsma, Thomas W.; Zhang, Changyong; Oostrom, Martinus

    2012-02-24

    The use of air-water, {Theta}{sub wa}, or air-liquid contact angles is customary in surface science, while oil-water contact angles {Theta}{sub ow}, are of paramount importance in subsurface multiphase flow phenomena including petroleum reocovery, nonaqueous phase liquid fate and transport, and geological carbon sequestration. In this paper we determine both the air-water and oil-water contact angles of silica surfaces modified with a diverse selection of silanes, using hexadecane as the oil. The silanes included alkylsilanes, alkylarylsilanes, and silanes with alkyl or aryl groups that are functionalized with heteroatoms such as N, O, and S. These silanes yielded surfaces with wettabilities from water-wet to oil wet, including specific silanized surfaces functionalized with heteroatoms that yield intermediate wet surfaces. The oil-water contact angles for clean and silanized surfaces, excluding one partially fluorinated surface, correlate linearly with air-water contact angles with a slope of 1.41 (R = 0.981, n = 13). These data were used to examine a previously untested theoretical treatment relating air-water and oil-water contact angles in terms of fluid interfacial energies. Plotting the cosines of these contact angles against one another, we obtain a linear relationship in excellent agreement with the theoretical treatment; the data fit cos {Theta}{sub ow} = 0.667 cos {Theta}{sub ow} + 0.384 (R = 0.981, n = 13), intercepting cos {Theta}{sub ow} = -1 at -0.284. The theoretical slope, based on the fluid interfacial tensions {Theta}{sub wa}, {Theta}{sub ow}, and {Theta}{sub oa}, is 0.67. We also demonstrate how silanes can be used to alter the wettability of the interior of a pore network micromodel device constructed in silicon/silica with a glass cover plate. Such micromodels are used to study multiphase flow phenomena. The contact angle of the resulting interior was determined in situ. An intermediate wet micromodel gave a contact angle in excellent agreement

  13. On the influence of surface tension during the impact of particles on a liquid-gaseous interface

    Science.gov (United States)

    Kintea, D. M.; Breitenbach, J.; Thammanna Gurumurthy, V.; Roisman, I. V.; Tropea, C.

    2016-01-01

    A numerical study of the water entry of non-rotating and rotating rigid spheres under varying impact angles and Weber numbers is presented. The numerical algorithm uses a finite-volume discretization and the interface between the liquid and the gaseous phase is described by means of a volume-of-fluid method. An appropriate mesh translation allows the boundary condition at the surface of the moving and rotating particle to be accounted for. The simulation results are validated with experiments and found to be in very good agreement both qualitatively (evolution of cavity shape) and quantitatively (motion of particle with respect to time). An investigation of the influence of particle rotation on its water entry behavior is carried out as well as an analysis of the effect of wettability upon cavity formation. Notably, wettability of the sphere plays a role during the penetration of a free liquid surface, even at higher Weber numbers. During impact of small particles at low Weber numbers, the influence of capillary forces rises and the force emerging at the three phase contact line becomes predominant. This force is taken into account and its influence on the impact behavior is presented. It is shown that the interface penetration behavior, either water entry or escaping from water, mostly depends on the Weber number, the solid to liquid density ratio, and the particle's wettability, while the impact angle has nearly no influence.

  14. Effect of surface tension on the dynamical behavior of bubble in rotating fluids under low gravity environment

    Science.gov (United States)

    Hung, R. J.; Tsao, Y. D.; Leslie, Fred W.; Hong, B. B.

    1988-01-01

    Time dependent evolutions of the profile of free surface (bubble shapes) for a cylindrical container partially filled with a Newtonian fluid of constant density, rotating about its axis of symmetry, have been studied. Numerical computations of the dynamics of bubble shapes have been carried out with the following situations: (1) linear functions of spin-up and spin-down in low and microgravity environments, (2) linear functions of increasing and decreasing gravity enviroment in high and low rotating cylidner speeds, (3) step functions of spin-up and spin-down in a low gravity environment, and (4) sinusoidal function oscillation of gravity environment in high and low rotating cylinder speeds. The initial condition of bubble profiles was adopted from the steady-state formulations in which the computer algorithms have been developed by Hung and Leslie (1988), and Hung et al. (1988).

  15. SURFACE TENSION OF SERUM : VIII. FURTHER EVIDENCE INDICATING THE EXISTENCE OF A SUPERFICIAL POLARIZED LAYER OF MOLECULES AT CERTAIN DILUTIONS.

    Science.gov (United States)

    du Noüy, P L

    1924-04-30

    The assumption has been made in preceding papers that, at a given concentration of 1:10,000, in the vessels used in our experiments, a monomolecular oriented layer was formed. Such a layer might be supposed to prevent the free escape of water molecules from the surface into the air, at least to a certain extent. In order to check this assumption, the rate of evaporation of solutions of serum at different concentrations was measured. It was found that, under the conditions of the experiments, in a progression of dilutions from 10(-1) to 10(-6), the slowest evaporation took place at a concentration of 1:10,000. In a few cases (less than 20 per cent), evaporation was slower at a different concentration, but always within the same range (between 10(-3) and 10(-5)), not far from 10(-4).

  16. Surface tension of calcium hydroxide associated with different substances Tensão superficial do hidróxido de cálcio associado a diferentes substâncias

    Directory of Open Access Journals (Sweden)

    Carlos Estrela

    2005-06-01

    Full Text Available The purpose of this study was to evaluate the surface tension of calcium hydroxide (CH associated with different substances (deionized distilled water, camphorated paramonochlorophenol, 2% chlorhexidine digluconate, Otosporin, 3% sodium lauryl ether sulphate; Furacin, PMC Furacin using tensiometer. The action of the substances studied on the dentinal structure enhances the property of surface tension. This method consists in the application of force to separate a platinum ring immersed in the substances. Thus, torsion was applied to the screw until the platinum ring separated during substances testing. Considering the methodology applied, the following can be concluded: distilled water alone or associated with CH presented a high surface tension (70.00 and 68.40 dynes/cm; calcium hydroxide in association with anionic detergent showed low surface tension (31.60 dynes/cm; camphorated paramonochlorophenol plus CH presented low surface tension (37.50 dynes/cm; 2% chlorhexidine associated with calcium hydroxide showed high surface tension values (58.00 dynes/cm; Otosporin plus calcium hydroxide showed low surface tension (35.40 dynes/cm; paramonochlorophenol Furacin mixed with calcium hydroxide presented surface tension equal to 45.50 dynes/cm; sodium hypochlorite presented high surface tension (75.00 dynes/cm. Antimicrobial agents more indicated in endodontics, i.e. CH, chlorhexidine and hypochlorite, presented the highest surface tension.Estudou-se a tensão superficial do hidróxido de cálcio associado a diferentes substâncias (água destilada deionizada, paramonoclorofenol canforado, digluconato de clorexidina 2%, Otosporin, sulfato éter lauril sódio 3%, furacin, PMC furacin usando tensiômetro. O modelo experimental consistiu na aplicação de uma força para separar um anel de platina imerso na superfície das substâncias, exercido por um tensiômetro. Considerando a metodologia aplicada, pode-se concluir: a água destilada isolada ou

  17. 智能测试磁性液体表面张力系数的实验研究%Experimental Study on the Surface Tension Coefficient of Magnetic Fluids with the Intelligence Test

    Institute of Scientific and Technical Information of China (English)

    吴继荣; 李晓琦; 安宏

    2012-01-01

    利用同种磁性液体表面张力智能测试仪在不同边界条件下对磁性液体的表面张力系数进行了测试,实验结果表明,磁性液体的表面张力系数与磁场强度及其饱和磁化强度成正比.利用不同的仪器、在相同边界条件下对同种磁性液体表面张力系数测试的结果表明,智能仪器能够准确获取磁性液体液膜断前、断后的电压值,减小依靠人眼盲读电压值产生的误差,测试精度比传统仪器提高了4.14%.%The surface tension coefficient of the magnetic fluids was measured with the magnetic fluids surface tension intelligent tester under different boundary conditions. And the results show that the surface tension coefficient of the magnetic fluids varies directly as the magnetic density and the saturation magnetization. The test results for the magnetic liquid surface tension coefficient by different instruments under the same boundary conditions show that the magnetic fluids surface tension intelligent tester can record the voltage before and after the break of the magnetic fluids membrane, reduce the measured error read by eyes and enhance the accuracy by 4. 14% compared with the traditional tester under the same boundary conditions.

  18. Pair correlation functions and the wavevector-dependent surface tension in a simple density functional treatment of the liquid-vapour interface

    Science.gov (United States)

    Parry, A. O.; Rascón, C.; Willis, G.; Evans, R.

    2014-09-01

    We study the density-density correlation function G(r, r‧) in the interfacial region of a fluid (or Ising-like magnet) with short-ranged interactions using square gradient density functional theory. Adopting a simple double parabola approximation for the bulk free-energy density, we first show that the parallel Fourier transform G(z, z‧ q) and local structure factor S(z q) separate into bulk and excess contributions. We attempt to account for both contributions by deriving an interfacial Hamiltonian, characterised by a wavevector dependent surface tension σ(q), and then reconstructing density correlations from correlations in the interface position. We show that the standard crossing criterion identification of the interface, as a surface of fixed density (or magnetization), does not explain the separation of G(z, z‧ q) and the form of the excess contribution. We propose an alternative definition of the interface position based on the properties of correlations between points that ‘float’ with the surface and show that this describes the full q and z dependence of the excess contributions to both G and S. However, neither the ‘crossing-criterion’ nor the new ‘floating interface’ definition of σ(q) are quantities directly measurable from the total structure factor Stot(q) which contains additional q dependence arising from the non-local relation between fluctuations in the interfacial position and local density. Since it is the total structure factor that is measured experimentally or in simulations, our results have repercussions for earlier attempts to extract and interpret σ(q).

  19. Reproducible Construction of Surface Tension-Mediated Honeycomb Concave Microwell Arrays for Engineering of 3D Microtissues with Minimal Cell Loss.

    Science.gov (United States)

    Lee, GeonHui; Lee, JaeSeo; Oh, HyunJik; Lee, SangHoon

    2016-01-01

    The creation of engineered 3D microtissues has attracted prodigious interest because of the fact that this microtissue structure is able to mimic in vivo environments. Such microtissues can be applied extensively in the fields of regenerative medicine and tissue engineering, as well as in drug and toxicity screening. Here, we develop a novel method of fabricating a large number of dense honeycomb concave microwells via surface tension-mediated self-construction. More specifically, in order to control the curvature and shape of the concavity in a precise and reproducible manner, a custom-made jig system was designed and fabricated. By applying a pre-set force using the jig system, the shape of the honeycomb concave well was precisely and uniformly controlled, despite the fact that wells were densely packed. The thin wall between the honeycomb wells enables the minimization of cell loss during the cell-seeding process. To evaluate the performance of the honeycomb microwell array, rat hepatocytes were seeded, and spheroids were successfully formed with uniform shape and size. Liver-specific functions such as albumin secretion and cytochrome P450 were subsequently analyzed. The proposed method of fabricating honeycomb concave wells is cost-effective, simple, and reproducible. The honeycomb well array can produce multiple spheroids with minimal cell loss, and can lead to significant contributions in tissue engineering and organ regeneration.

  20. Nucleation, growth and transport modelling of helium bubbles under nuclear irradiation in lead-lithium with the Self-consistent nucleation theory and surface tension corrections

    CERN Document Server

    Fradera, Jorge

    2013-01-01

    Helium (He) nucleation in liquid metal breeding blankets of a DT fusion reactor may have a significant impact regarding system design, safety and operation. Large He production rates are expected due to tritium (T) fuel self-sufficiency requirement, as both, He and T, are produced at the same rate. Low He solubility, local high concentrations, radiation damage and fluid discontinuities, among other phenomena, may yield the necessary conditions for He nucleation. Hence, He nucleation may have a significant impact on T inventory and may lower the T breeding ratio. A model based on the self-consistent nucleation theory (SCT) with a surface tension curvature correction model has been implemented in OpenFoam(r) CFD code. A modification through a single parameter of the necessary nucleation condition is proposed in order to take into account all the nucleation triggering phenomena, specially radiation induced nucleation. Moreover, the kinetic growth model has been adapted so as to allow for the transition from a cr...

  1. Eletromiograma de superfície durante stress experimental como subsídio no diagnóstico da cefaléia tensional: resultados em 100 casos Surface scalp and neck electromyography with stress as diagnostic criterion in chronic tension headache: results in 100 cases

    Directory of Open Access Journals (Sweden)

    Ceme Ferreira Jordy

    1995-09-01

    Full Text Available Eletromiograma de superfície foi realizado no crânio e pescoço, durante stress provocado por frio, em 100 pacientes sofrendo cefaléia crônica isolada. Os resultados de diagnóstico obtidos com a eletromiografia revelaram erro de 24% a 32% na avaliação clínica da cefaléia tensional segundo os critérios anamnésicos referendados pelo Comitê de Classificação das Cefaléias, da Sociedade Internacional de Cefaléia (1988. A eletromiografia durante stress é proposta como novo critério de diagnóstico da Cefaléia tensional.We report the use of surface scalp and neck electromyography during experimental stress state in a series of 100 out-patients suffering from chronic tension headache. Results revealed a 24% to 32% of diagnostic errors in the diagnostic obtained by routine anamnestic procedures and following the criteria recommended by the Headache Classification Commitee of the International Headache Society (1988. The electromyography with stress is proposed as a new diagnostic criterion for tension headache.

  2. 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.

  3. Competing effects of viscosity and surface-tension depression on the hygroscopicity and CCN activity of laboratory surrogates for oligomers in atmospheric aerosol

    Science.gov (United States)

    Hodas, N.; Zuend, A.; Shiraiwa, M.; Flagan, R. C.; Seinfeld, J.; Schilling, K.; Berkemeier, T.

    2015-12-01

    The presence of oligomers in biomass burning aerosol, as well as secondary organic aerosol derived from other sources, influences particle viscosity and can introduce kinetic limitations to water uptake. This, in turn, impacts aerosol optical properties and the efficiency with which these particles serve as cloud condensation nuclei (CCN). To explore the influence of organic-component viscosity on aerosol hygroscopicity, the water-uptake behavior of aerosol systems comprised of polyethylene glycol (PEG) and mixtures of PEG and ammonium sulfate (AS) was measured under sub- and supersaturated relative humidity (RH) conditions. Experiments were conducted with systems containing PEG with average molecular weights ranging from 200 to 10,000 g/mol, corresponding to a range in viscosity of 0.004 - 4.5 Pa s under dry conditions. While evidence suggests that viscous aerosol components can suppress water uptake at RH activity with increasing PEG molecular weight was observed. We attribute this to an increase in the efficiency with which PEG serves as a surfactant with increasing molecular weight. This effect is most pronounced for PEG-AS mixtures and, in fact, a modest increase in CCN activity is observed for the PEG 10,000-AS mixture as compared to pure AS, as evidenced by a 4% reduction in critical activation diameter. Experimental results are compared with calculations of hygroscopic growth at thermodynamic equilibrium using the Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients model and the potential influence of kinetic limitations to observed water uptake is further explored with the Kinetic Multi-Layer Model of Gas-Particle Interactions. Results suggest the competing effects of organic-component viscosity and surface-tension depression may lead to RH-dependent differences in hygroscopicity for oligomers and other surface-active compounds present in atmospheric aerosols, for which PEG serves as a surrogate in these experiments.

  4. Effect of surface tension anisotropy on the interface morphological stability of deep cellular crystal%各向异性表面张力对深胞晶界面形态稳定性的影响

    Institute of Scientific and Technical Information of China (English)

    蒋晗; 陈明文; 史国栋; 王涛; 王自东

    2016-01-01

    In this paper, we study the effect of anisotropic surface tension on the interface morphological stability of deep cel-lular crystal during directional solidification. We assume that the process of solidification is viewed as a two-dimensional problem, the anisotropic surface tension is a four-fold symmetry function, the solute diffusion in the solid phase is neg-ligible, the thermodynamic properties are the same for both solid and liquid phases, and there is no convection in the system. On the basis of the basic state solution for the deep cellular crystal in directional solidification, by the matched asymptotic expansion method and the multiple variable expansion method, we obtain the asymptotic solution, and then the quantization condition of interfacial morphology for deep cellular crystal is obtained. The results show that by comparison with the directional solidification system of surface tension isotropy, the in-terface morphological stability of surface tension anisotropy also possesses two types of global instability mechanisms:the global oscillatory instability (GTW-mode), whose neutral modes yield strong oscillatory dendritic structures, and the low-frequency instability (IF-mode), whose neutral modes yield weakly oscillatory cellular structures. Both of the two global instability mechanisms have the symmetrical mode (S-mode) and the anti-symmetrical mode (A-mode), and the growth rate of the S-mode with the same index n is greater than that of the A-mode. In this sense we say that the S-mode is more dangerous than the A-mode. All the neutral curves of the GTW-S-modes and LF-S-modes divide the parameter plane into two subdomains: the stable domain and the unstable domain. In the paper we show the neural curves of the GTW-S-modes and LS-S-modes for various n, respectively. It is seen that among all the GTW-S-modes (n = 0, 1, 2), the GTW-S-mode with n = 0 is the most dangerous oscillatory mode, while among all the LF-S-modes (n=0, 1, 2), the LF-S-mode with

  5. 一个基于UNIQUAC Gibbs自由能模型的液体表面张力方程%A NEW SURFACE TENSION EQUATION FOR LIQUID MIXTURES BASED ON UNIQUAC GIBBS FREE ENERGY MODEL

    Institute of Scientific and Technical Information of China (English)

    李春喜; 王子镐; 宋红艳

    2001-01-01

    Based on the thermodynamic definition of surface tension and UNIQUAC Gibbs free energy model,a two-parameter surface tension equation is derived. σm=∑ixiσi-RT∑i(xiqi)/(∑jθjτji)∑jθj(τji)/(A)T,P,x In this equation,the first term represents pure component contribution to the surface tension of a mixture,and the second term represents the excess surface tension due to the molecular interaction difference between different components. For ideal solution,the excess surface tension term disappeared,and the surface tension is equivalent to that of pure component averaged with mole fraction.The feasibility of the new equation has been tested for 90 binary and 15 multicomponent systems and the AAD is found to be 0.44% and 1.57%, respectively. Results showed good precision by using the developed equation with simplicity and reliability for practical uses.%根据表面张力的热力学定义以及UNIQUAC过量Gibbs自由能表达式,推导出了一个新的两参数表面张力方程,σm=∑ixiσi-RT∑i(xiqi)/(∑jθjτji)∑jθj(τji)/(A)T,P,x该方程第一项为纯组分对液体混合物表面张力的贡献,第二项为不同组分间作用力的差异引起的过量表面张力。对于理想溶液,过量表面张力项为零,因此,混合物的表面张力等于各个纯组分表面张力的摩尔分数平均值。通过90个二元体系和15个多元体系表面张力的计算,对新方程的性能进行了测试,发现其对二元体系和多元体系计算的总平均相对偏差分别为0.44%和1.57%。结果表明,该模型计算精度高,公式简单实用,而且对各种体系具有广泛的适应性。

  6. Surface folding-induced attraction and motion of particles in a soft elastic gel: cooperative effects of surface tension, elasticity, and gravity.

    Science.gov (United States)

    Chakrabarti, Aditi; Chaudhury, Manoj K

    2013-12-17

    We report some experimental observations regarding a new type of long-range interaction between rigid particles that prevails when they are suspended in an ultrasoft elastic gel. A denser particle submerges itself to a considerable depth inside the gel and becomes elasto-buoyant by balancing its weight against the elastic force exerted by the surrounding medium. By virtue of a large elasto-capillary length, the surface of the gel wraps around the particle and closes to create a line singularity connecting the particle to the free surface of the gel. A substantial amount of tensile strain is thus developed in the gel network parallel to the free surface that penetrates to a significant depth inside the gel. The field of this tensile strain is rather long-range because of a large gravito-elastic correlation length and sufficiently strong to pull two submerged particles into contact. The particles move toward each other with an effective force following an inverse linear distance law. When more monomers or dimers of the particles are released inside the gel, they orient rather freely inside the capsules where they are located and attract each other to form closely packed clusters. Eventually, these clusters themselves interact and coalesce. This is an emergent phenomenon in which gravity, capillarity, and elasticity work in tandem to create a long-range interaction. We also present the results of a related experiment, in which a particle suspended inside a thickness-graded gel moves accompanied by the continuous folding and the relaxation of the gel's surface.

  7. The effect of surface tension and association on the homogeneous binary spontaneous condensation in a non-steady state subsonic flow of steam. Zum Einfluss der Oberflaechenspannung und Assoziation auf die homogene binaere Spontankondensation in einer instationaeren Unterschalldampfstroemung

    Energy Technology Data Exchange (ETDEWEB)

    Spiegel, G.H.

    1987-05-21

    This work deals with the spontaneous homogneous condensation process of diluted binary steam, which is increasing in importance in many technical and natural processes. In a deep and generally valid theoretical investigation, the introductory cycle of phase change (the binary nucleus formation) and the subsequent process of growth are comprehensively analysed. Similar serious problems in theoretical prediction are found in binary systems with a surface active component. Particularly when these are present in diluted form, the macroscopic surface tension leads to quite insufficient theoretical results.This fact also found by other workers is due to a changed molecule distribution compared to the macroscopic case in the resulting liquid phase during transition to the micro-clusters important in nucleus formation. As both binary solutions examined in this work belong to this category, two recently proposed theoretical models for 'correcting' the surface tension are considered - the adsorption and the mono-layer model. However, it was found that both processes can only be used to a limited extent for the interesting speeds of cooling. It is demonstrated by a comparative analysis carried out for the first time in such detail that only the proposal resulting from this work to use the purely dynamic surface tension has general applicability. (orig./GL).

  8. Density, viscosity, surface tension, and molar volume of propylene glycol + water mixtures from 293 to 323 K and correlations by the Jouyban–Acree model

    Directory of Open Access Journals (Sweden)

    Ibrahim S. Khattab

    2017-02-01

    Full Text Available Density, viscosity, surface tension and molar volume of propylene glycol + water mixtures at 293, 298, 303, 308, 313, 318, and 323 K are reported, compared with the available literature data and the Jouyban–Acree model was used for mathematical correlation of the data. The mean relative deviation (MRD was used as an error criterion and the MRD values for data correlation of density, viscosity, surface tension and molar volume at different investigated temperatures are 0.1 ± 0.1%, 7.6 ± 6.4%, 3.4 ± 3.7%, and 0.4 ± 0.4%, respectively. The corresponding MRDs for the predicted properties after training the model using the experimental data at 298 K are 0.1 ± 0.2%, 12.8 ± 9.3%, 4.7 ± 4.1% and 0.6 ± 0.5%, respectively for density, viscosity, surface tension, and molar volume data.

  9. Lignification and tension wood.

    Science.gov (United States)

    Pilate, Gilles; Chabbert, Brigitte; Cathala, Bernard; Yoshinaga, Arata; Leplé, Jean-Charles; Laurans, Françoise; Lapierre, Catherine; Ruel, Katia

    2004-01-01

    Hardwood trees are able to reorient their axes owing to tension wood differentiation. Tension wood is characterised by important ultrastructural modifications, such as the occurrence in a number of species, of an extra secondary wall layer, named gelatinous layer or G-layer, mainly constituted of cellulose microfibrils oriented nearly parallel to the fibre axis. This G-layer appears directly involved in the definition of tension wood mechanical properties. This review gathers the data available in the literature about lignification during tension wood formation. Potential roles for lignin in tension wood formation are inferred from biochemical, anatomical and mechanical studies, from the hypotheses proposed to describe tension wood function and from data coming from new research areas such as functional genomics.

  10. 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.

  11. Medidas de tensão superficial pelo método de contagem de gotas: descrição do método e experimentos com tensoativos não-iônicos etoxilados Surface tension measurement by drop counting method: method description and experiments with etoxilated non-ionic surfactants

    Directory of Open Access Journals (Sweden)

    Érico Teixeira Neto

    2009-01-01

    Full Text Available Surface tension knowledge of surfactants aqueous solutions is important during amphiphilic molecule manufacturing and new product development, as feedback information to handle synthesis parameters to target performance. Drop counting method is an interesting simplification of drop weight method for surface tension measurements. A simple laboratory measurement device, with capability for temperature control, was assembled to allow investigation of ethoxylated surfactants. The implementation of the method was preceded by a detailed investigation of two factors that may affect the measured surface tension: drop formation velocity and surfactant ethoxylation degree. The limitations of the method are discussed on this basis.

  12. 粗糙表面上的接触角滞后现象与滞后张力%Contact Angle Hysteresis and Hysteresis Tension on Rough Solid Surface

    Institute of Scientific and Technical Information of China (English)

    王晓东; 彭晓峰; 王补宣

    2004-01-01

    Observation and measurement were conducted to investigate contact angle and its hysteresis on rough surface. The experimental results indicate that the increase in solid surface roughness enlarges advancing contact angle and decreases receding contact angle, resulting in enhanced hysteresis. It was observed that when Young's contact angle θy < 90°, as the roughness of solid surface increased the extent of the decrease in receding contact angle exceeded that of the increase in advancing contact angle. Based on the experimental observations, the concept of hysteresis tension was introduced to describe the contact angle hysteresis behavior on rough solid surface. The model provides a thoughtful understanding of the physical nature of contact angle hysteresis, in particular an instructive description of the influence of surface roughness on the hysteresis. The prediction of the model is found in quite good agreement with the experimental observation and measurement.

  13. 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

  14. 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

  15. ZrO2对高硼硅玻璃高温粘度和表面张力的影响%Effect of ZrO2 on Viscosity and Surface Tension of Borosilicate Glass

    Institute of Scientific and Technical Information of China (English)

    刘尧龙; 陆平; 程金树

    2016-01-01

    Due to the high melting temperature ,borosilicate glass erode refractory strongly .ZrO2 dissolved into the glass change viscosity and surface of mother glass , which also bring about many and various product defects .In this paper , a small amount of ZrO 2 were introduced into the mother glass .High temperature viscosity was tested by the rotating method and high temperature surface tension was tested by the sessile drop method .The results indicate that viscosity of the glass above 1530 ℃almost no change and viscosity of the glass below 1530 ℃ greatly increase with increasing ZrO 2 content .At same time , surface tension is increasing mono-tonically .Surface tension reduce as the temperature increases .%高硼硅玻璃由于熔化温度高,对耐火材料侵蚀严重,ZrO2溶解到玻璃中后使其高温粘度和表面张力发生变化,是产生玻璃缺陷的重要原因之一。通过在母体玻璃中引入少量ZrO2,采用旋转粘度法测试玻璃的高温粘度,采用静滴法测试玻璃的高温表面张力。结果表明,随着含量的增加,ZrO2对玻璃在1530℃以上的粘度影响不大,但可使1530℃以下的粘度有较大提高。玻璃的高温表面张力随着ZrO2含量的增加单调递增,随着温度的升高而降低。

  16. Tension-oriented cell divisions limit anisotropic tissue tension in epithelial spreading during zebrafish epiboly.

    Science.gov (United States)

    Campinho, Pedro; Behrndt, Martin; Ranft, Jonas; Risler, Thomas; Minc, Nicolas; Heisenberg, Carl-Philipp

    2013-12-01

    Epithelial spreading is a common and fundamental aspect of various developmental and disease-related processes such as epithelial closure and wound healing. A key challenge for epithelial tissues undergoing spreading is to increase their surface area without disrupting epithelial integrity. Here we show that orienting cell divisions by tension constitutes an efficient mechanism by which the enveloping cell layer (EVL) releases anisotropic tension while undergoing spreading during zebrafish epiboly. The control of EVL cell-division orientation by tension involves cell elongation and requires myosin II activity to align the mitotic spindle with the main tension axis. We also found that in the absence of tension-oriented cell divisions and in the presence of increased tissue tension, EVL cells undergo ectopic fusions, suggesting that the reduction of tension anisotropy by oriented cell divisions is required to prevent EVL cells from fusing. We conclude that cell-division orientation by tension constitutes a key mechanism for limiting tension anisotropy and thus promoting tissue spreading during EVL epiboly.

  17. Tension chylothorax following pneumonectomy

    Directory of Open Access Journals (Sweden)

    Hemang Yadav

    2015-01-01

    Full Text Available Post-pneumonectomy chylothorax is an uncommon complication following surgery, with an estimated incidence of less than 0.7%. Post-pneumonectomy tension chylothorax, where rapid accumulation of chyle in the post-pneumonectomy space results in hemodynamic compromise, is exceedingly rare, with just 7 cases previously reported. All prior cases of tension chylothorax were managed operatively with decompressive chest tube placement followed by open thoracic duct repair. Our case is the first reported tension chylothorax to be managed conservatively by thoracostomy drainage coupled with a period of parenteral nutrition followed by a medium chain triglyceride-restricted diet.

  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. Blood Vessel Tension Tester

    Science.gov (United States)

    1978-01-01

    In the photo, a medical researcher is using a specially designed laboratory apparatus for measuring blood vessel tension. It was designed by Langley Research Center as a service to researchers of Norfolk General Hospital and Eastern Virginia Medical School, Norfolk, Virginia. The investigators are studying how vascular smooth muscle-muscle in the walls of blood vessels-reacts to various stimulants, such as coffee, tea, alcohol or drugs. They sought help from Langley Research Center in devising a method of measuring the tension in blood vessel segments subjected to various stimuli. The task was complicated by the extremely small size of the specimens to be tested, blood vessel "loops" resembling small rubber bands, some only half a millimeter in diameter. Langley's Instrumentation Development Section responded with a miniaturized system whose key components are a "micropositioner" for stretching a length of blood vessel and a strain gage for measuring the smooth muscle tension developed. The micropositioner is a two-pronged holder. The loop of Mood vessel is hooked over the prongs and it is stretched by increasing the distance between the prongs in minute increments, fractions of a millimeter. At each increase, the tension developed is carefully measured. In some experiments, the holder and specimen are lowered into the test tubes shown, which contain a saline solution simulating body fluid; the effect of the compound on developed tension is then measured. The device has functioned well and the investigators say it has saved several months research time.

  20. 药液表面张力和黏度对草甘膦药效的影响及其机理研究%Influences of surface tension and liquid viscosity on the efficacy of glyphosate and its mechanism

    Institute of Scientific and Technical Information of China (English)

    张利斌; 张庆贺; 韩玉军; 陶波

    2011-01-01

    通过添加有机硅助剂和丙三醇调节草甘膦药液的表面张力和黏度,测定其对草甘膦药液液滴的物理性状及生物活性的影响.结果表明:降低药液的表面张力,雾滴的铺展直径增加,干燥时间缩短,药液的黏度以及在杂草叶片表面的最大稳定持留量没有显著性变化;草甘膦对杂草的防效表现为先升高后降低,对阔叶杂草最高目测防效和鲜重防效可提高42%和41%,对禾本科杂草防效可提高37%和37%.增加草甘膦的药液黏度,药液在杂草叶片上的最大稳定持留量增加,表面张力降低,对雾滴的干燥时间和铺展直径影响很小;草甘膦对阔叶杂草最高目测防效和鲜重防效可提高42%和41%,对禾本科杂草的防效可提高42%和42%.适当降低草甘膦药液的表面张力或增加其黏度均可提高其对杂草的防除效果.%This study was aimed to regulate the surface tension and viscosity of glyphosate by the organosilicone and glycerol, and measure the influence of physical characters of liquid droplets and biological activity. The results showed that, by reducing the surface tension of liquid, spreading diameter of the droplet was increased, and the drying time was shortened, but the viscosity of liquid and maximum retention on weed blade surface were not significantly changed. The inhibition rate to weeds firstly increased and then decreased, and the maximum control of visual and fresh weight of broadleaf weeds were increased by 37% and 37%, and those of grass weeds were increased by 42% and 41%. By increasing the viscosity, the maximum retention on weed blade surface was increased, and the surface tension was reduced, but the drying time of droplets and the spreading diameter were not significantly changed. The maximum control of visual and fresh weight of broadleaf weeds were increased by 42% and 41%, and those of grass weeds were increased by 42% and 42%. Moderate reduction of surface tension or

  1. Inspection and analysis of water quality based on Ramam spectrum and surface tension%拉曼光谱和表面张力用于水质检测与分析

    Institute of Scientific and Technical Information of China (English)

    文军

    2014-01-01

    使用激光拉曼光谱仪测试了蒸馏水、瓶装饮用水和自来水的室温拉曼光谱,并用拉脱法测量了表面张力。实验结果表明:蒸馏水、瓶装饮用水和自来水的拉曼光谱基本相似,蒸馏水的拉曼光谱相对光滑,峰强度较大;自来水和瓶装饮用水的拉曼光谱出现杂峰与毛刺,峰强度降低,峰形宽化。蒸馏水、瓶装饮用水和自来水的表面张力随温度升高而减小。水中杂质物和溶解物对水中氢键的影响,使水分子团簇结构强化,极化率降低,振动能量减弱,拉曼光谱峰强度降低,表面张力增大。%The room temperature Raman spectra of distilled water ,bottled drinking water and tap water were recorded by laser Raman spectrometer ,and the surface tensions of these samples were measured by pull-out method .The results showed that the Raman spectra of distilled water ,bottled drinking water and tap water were similar in general .However ,distilled water had a smoother and stronger spectrum .While many impurity peaks and burrs appeared in the spectra of tap water and bot-tled drinking water which had lower and broad spectral peaks .The surface tensions of these samples decreased with increasing temperature .The influence of impurities on hydrogen bonds strengthened the clusters of water molecules and decreased the polarizability .Thus the bond vibration energy de-creased and led to lower Raman peak intensity and bigger surface tension .

  2. Tensión Superficial de Soluciones Acuosas Diluidas de Isómeros de Pentanodiol a 283.15 K Surface Tension of Dilute Aqueous Solutions of Pentanediol Isomers at 283.15 K

    Directory of Open Access Journals (Sweden)

    Manuel S Páez

    2009-01-01

    Full Text Available Se estudia el efecto que la posición de los grupos OH tiene sobre la tensión superficial de los isómeros del pentanodiol. La tensión superficial a 283.15 K de soluciones acuosas de 1,2-pentanodiol (12PD, 2,4-pentanodiol (24PD, 1,4-pentanodiol (14PD y 1,5-pentanodiol (15PD fueron medidas como una función de la concentración usando el método de ascenso capilar, en especial en la región diluida. Se evalúa la constante de centros de enlace de acuerdo con el modelo propuesto por Connors para solutos líquidos y los coeficientes de actividad a dilución infinita según el procedimiento sugerido por Gracia-Fadrique. Los resultados muestran la dependencia de la tensión superficial con la posición relativa de los grupos hidroxilos en la molécula de soluto y con el tamaño de la cadena alquílica expuesta al solvente.The effect of the position of OH groups on the surface tension of pentanodiol isomers is studied. Surface tension at 283.15 K of aqueous solutions of 1,2-pentanediol (12PD, 2,4-pentanediol (24PD, 1,4-pentanediol (14PD and 1,5-pentanediol (15PD were measured as a function of the concentration using the method of capillary rise, especially in the diluted region. The binding site constant is evaluated using the model proposed by Connors for liquid solutes and the activity coefficients for infinite dilution according to the procedure suggested by Gracia-Fadrique. The results show the dependence of the surface tension with the relative position of the hydroxylic groups in the solute molecule and with the size of the alquilic chain exposed to the solvent.

  3. The Tension Literature.

    Science.gov (United States)

    Frederick, A. B.

    This is a bibliography of literature on the subject of tension. Books, films, and periodicals with a bearing on stress, relaxation, anxiety, and/or methods of controlling stress are listed from the fields of physiology, psychology, and philosophy. New methods such as transcendental meditation and biofeedback are analyzed briefly and criteria are…

  4. Rein tension during canter

    NARCIS (Netherlands)

    Egenvall, Agneta; Eisersiö, Marie; Rhodin, Marie; van Weeren, P.R.; Roepstorff, Lars

    2015-01-01

    Riders generally use reins as a means for communication with the horse. At present, the signalling pattern is poorly understood. The aim of this study was to illustrate and analyse the rein tension patterns in a number of rider/horse combinations across a variety of exercises in the canter gait. Our

  5. 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...

  6. 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...

  7. A molecular dynamics study on surface properties of supercooled water

    Institute of Scientific and Technical Information of China (English)

    Lü; Yongjun

    2006-01-01

    [1]Basu J K,Hazra S,Sanyal M K.Growth mechanism of Langmuir-Blodgett films.Phys Rev Lett,1999,82:4675-4678[2]Taylor R S,Shields R L.Molecular-dynamics simulations of the ethanol liquid-vapor interface.J Chem Phys,2003,119:12569-12576[3]Velev O D,Gurkov T D,Ivanov I B,et al.Abnormal thickness and stability of nonequilibrium liquid films.Phys Rev Lett,1995,75:264-267[4]Weng J G,Park S,Lukes J R,et al.Molecular dynamics investigation of thickness effect on liquid films.J Chem Phys,2000,113:5917-5923[5]Zakharov V V,Brodskaya E N,Laaksonen A.Surface tension of water droplets:A molecular dynamics study of model and size dependencies.J Chem Phys,1997,107:10675-10683[6]Wang J Z,Chen M,Guo Z Y.A two-dimensional molecular dynamics simulation of liquid-vapor nucleation.Chin Sci Bull,2003,48(7):623-626[7]Guissani Y,Guillot B.A computer simulation study of the liquid-vapor coexistence curve of water.J Chem Phys,1993,98:8221-8235[8]Wilson M A,Pohorille A,Pratt L R.Surface potential of the water liquid-vapor interface.J Chem Phys,1988,88:3281-3285[9]Alejandre J,Tildesley D J,Chapela G A.Molecular dynamics simulation of the orthobaric densities and surface tension of water.J Chem Phys,1995,102:4574-4583[10]Matsumoto M,Kataoka Y.Study on liquid-vapor interface of water (Ⅰ):Simulational results of thermodynamic properties and orientational structure.J Chem Phys,1988,88:3233-3245[11]Floriano M A,Angell C A.Surface tension and molar surface free energy and entropy of water to-27.2℃.J Phys Chem,1990,94:4199-4202[12]Jorgensen W L,Chandrasekhar J,Madura J D.Comparison of simple potential functions for simulating liquid water.J Chem Phys,1993,79:926-935[13]Berendsen H J C,Grigera J R,Straatsma T P.The missing term in effective pair potentials.J Phys Chem,1987,91:6269-6271[14]Arbuckle B W,Clancy P.Effects of the Ewald sum on the free energy of the extended simple point charge model for water.J Chem Phys,2002,116:5090-5098[15]Tarazona P,Chacon E,Reinaldo-Falagan M,et al

  8. Coulomb string tension, asymptotic string tension, and the gluon chain

    Science.gov (United States)

    Greensite, Jeff; Szczepaniak, Adam P.

    2015-02-01

    We compute, via numerical simulations, the nonperturbative Coulomb potential of pure SU(3) gauge theory in Coulomb gauge. We find that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.

  9. Tensão superficial estática de soluções aquosas com óleos minerais e vegetais utilizados na agricultura Surface tension of mineral oils and vegetable oils

    Directory of Open Access Journals (Sweden)

    Cristina G. de Mendonça

    2007-01-01

    Full Text Available O trabalho teve como objetivo avaliar a tensão superficial estática de soluções aquosas com formulações de óleos minerais e vegetais emulsionáveis utilizados como adjuvantes na agricultura. Os óleos minerais e vegetais, quando adicionados aos produtos fitossanitários, podem imprimir características desejáveis à calda de pulverização, como reduzir a tensão superficial em soluções aquosas, possibilitar maior contato da calda com a superfície vegetal ou reduzir o potencial de deriva durante as pulverizações. Foram testados os seguintes produtos comerciais: óleos minerais (Assist, Attach, Dytrol, Iharol, Mineral Oil, Spinner, Sunspray-E e Triona e óleos vegetais (Agrex'oil Vegetal, Crop Oil, Natur'l Óleo, Óleo Vegetal Nortox e Veget Oil, todos com registro de uso na agricultura. A tensão superficial das soluções aquosas foi avaliada em 11 concentrações para cada produto (0,025; 0,05; 0,1; 0,25; 0,5; 0,75; 1,0; 1,5; 2,0; 2,5 e 3,0% v/v. Essa propriedade dos óleos minerais e dos óleos vegetais foi estimada medindo-se a massa das gotas formadas na extremidade de uma bureta. Ao conjunto de dados obtidos para cada produto, na avaliação da tensão superficial, foram determinadas as análises de variância e de regressão, ajustando-se os dados ao Modelo de Mitscherlich. Entre os óleos minerais, destacaram-se os produtos: Assist, Dytrol, Iharol e Mineral Oil por apresentarem as menores tensões superficiais mínimas estimadas pelo Modelo, respectivamente, 29,255; 28,442; 26,097 e 28,584 mN m-1. Os óleos vegetais que apresentaram os menores valores de tensão superficial mínima estimados pelo Modelo, foram: Agrex' oil Vegetal (27,716 mN m-1, Natur'l óleo (28,216 mN m-1, Veget Oil (27,308 mN m-1 e Crop Oil (29,964 mN m-1.The aim of this work was to evaluate the surface tension of water emulsion with mineral oils and vegetable oils used as adjuvant. The mineral and vegetable oils when added to the agrochemicals can

  10. Elastic properties and mechanical tension of graphene

    Science.gov (United States)

    Ramírez, R.; Herrero, C. P.

    2017-01-01

    Room-temperature simulations of graphene have been performed as a function of the mechanical tension of the layer. Finite-size effects are accurately reproduced by an acoustic dispersion law for the out-of-plane vibrations that, in the long-wave limit, behaves as ρ ω2=σ k2+κ k4 . The fluctuation tension σ is finite (˜0.1 N/m) even when the external mechanical tension vanishes. Transverse vibrations imply a duplicity in the definition of the elastic constants of the layer, as observables related to the real area of the surface may differ from those related to the in-plane projected area. This duplicity explains the variability of experimental data on the Young modulus of graphene based on electron spectroscopy, interferometric profilometry, and indentation experiments.

  11. Elastic-Plastic J-Integral Solutions or Surface Cracks in Tension Using an Interpolation Methodology. Appendix C -- Finite Element Models Solution Database File, Appendix D -- Benchmark Finite Element Models Solution Database File

    Science.gov (United States)

    Allen, Phillip A.; Wells, Douglas N.

    2013-01-01

    No closed form solutions exist for the elastic-plastic J-integral for surface cracks due to the nonlinear, three-dimensional nature of the problem. Traditionally, each surface crack must be analyzed with a unique and time-consuming nonlinear finite element analysis. To overcome this shortcoming, the authors have developed and analyzed an array of 600 3D nonlinear finite element models for surface cracks in flat plates under tension loading. The solution space covers a wide range of crack shapes and depths (shape: 0.2 less than or equal to a/c less than or equal to 1, depth: 0.2 less than or equal to a/B less than or equal to 0.8) and material flow properties (elastic modulus-to-yield ratio: 100 less than or equal to E/ys less than or equal to 1,000, and hardening: 3 less than or equal to n less than or equal to 20). The authors have developed a methodology for interpolating between the goemetric and material property variables that allows the user to reliably evaluate the full elastic-plastic J-integral and force versus crack mouth opening displacement solution; thus, a solution can be obtained very rapidly by users without elastic-plastic fracture mechanics modeling experience. Complete solutions for the 600 models and 25 additional benchmark models are provided in tabular format.

  12. New sensitive micro-measurements of dynamic surface tension and diffusion coefficients: Validated and tested for the adsorption of 1-Octanol at a microscopic air-water interface and its dissolution into water.

    Science.gov (United States)

    Kinoshita, Koji; Parra, Elisa; Needham, David

    2017-02-15

    Currently available dynamic surface tension (DST) measurement methods, such as Wilhelmy plate, droplet- or bubble-based methods, still have various experimental limitations such as the large size of the interface, convection in the solution, or a certain "dead time" at initial measurement. These limitations create inconsistencies for the kinetic analysis of surfactant adsorption/desorption, especially significant for ionic surfactants. Here, the "micropipette interfacial area-expansion method" was introduced and validated as a new DST measurement having a high enough sensitivity to detect diffusion controlled molecular adsorption at the air-water interfaces. To validate the new technique, the diffusion coefficient of 1-Octanol in water was investigated with existing models: the Ward Tordai model for the long time adsorption regime (1-100s), and the Langmuir and Frumkin adsorption isotherm models for surface excess concentration. We found that the measured diffusion coefficient of 1-Octanol, 7.2±0.8×10(-6)cm(2)/s, showed excellent agreement with the result from an alternative method, "single microdroplet catching method", to measure the diffusion coefficient from diffusion-controlled microdroplet dissolution, 7.3±0.1×10(-6)cm(2)/s. These new techniques for determining adsorption and diffusion coefficients can apply for a range of surface active molecules, especially the less-characterized ionic surfactants, and biological compounds such as lipids, peptides, and proteins. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Elastic-Plastic J-Integral Solutions or Surface Cracks in Tension Using an Interpolation Methodology. Appendix C -- Finite Element Models Solution Database File, Appendix D -- Benchmark Finite Element Models Solution Database File

    Science.gov (United States)

    Allen, Phillip A.; Wells, Douglas N.

    2013-01-01

    No closed form solutions exist for the elastic-plastic J-integral for surface cracks due to the nonlinear, three-dimensional nature of the problem. Traditionally, each surface crack must be analyzed with a unique and time-consuming nonlinear finite element analysis. To overcome this shortcoming, the authors have developed and analyzed an array of 600 3D nonlinear finite element models for surface cracks in flat plates under tension loading. The solution space covers a wide range of crack shapes and depths (shape: 0.2 less than or equal to a/c less than or equal to 1, depth: 0.2 less than or equal to a/B less than or equal to 0.8) and material flow properties (elastic modulus-to-yield ratio: 100 less than or equal to E/ys less than or equal to 1,000, and hardening: 3 less than or equal to n less than or equal to 20). The authors have developed a methodology for interpolating between the goemetric and material property variables that allows the user to reliably evaluate the full elastic-plastic J-integral and force versus crack mouth opening displacement solution; thus, a solution can be obtained very rapidly by users without elastic-plastic fracture mechanics modeling experience. Complete solutions for the 600 models and 25 additional benchmark models are provided in tabular format.

  14. Measure of surface tension applied to monitor the purification of n-alkyl perfluoroalkanesulfonamides%表面张力测定用于监测N-烷基全氟烷基磺酰胺的纯化

    Institute of Scientific and Technical Information of China (English)

    周洪涛; 窦增培; 肖进新

    2011-01-01

    N-烷基全氟烷基磺酰胺(RfSO2 NHR,RfSO2,Rf,为全氟烷基,R为烷基)是一类重要的油溶性氟表面活性剂,通过全氟烷基磺酰氟和相应的胺制备.本文提供一种简单易行的纯化方法.将反应后的混合物首先经稀盐酸洗涤,除去未反应的胺,然后用去离子水洗涤.在水洗过程中,通过测定表面张力监控水洗过程:若水洗液的表面张力基本不再随水洗次数变化,则可判定杂质已经除去.以此可简单的检测N-烷基全氟烷基磺酰胺的纯化过程.该方法也可推广到其他多种类型的油溶性表面活性剂的纯化.以N-正丁基全氟辛基磺酰胺[CF3(CF2),SO2 NH(CH2),CH3]的合成为例说明该反应后混合物经去离子水洗涤后水洗液的表面张力达到约53 mN/m后不再变化,判定杂质已除去,进一步通过红外、1HNMR、19FNMR、元素分析方法确认其结构.%N-Alkyl perfluoroalkanesulfonamides ( RfSO2 NHR and RfSO2 NR2, in which Rf and R represent the perfluoroalkyl and alkyl groups, respectively ) are an important category of fluorinated surfactants applied in organic solvents. They were prepared from perfluoroalkanesulfonyl fluoride and conesponding amines. A simple and convenient method of purification was provided in this work. The resulted mixture after reaction was washed with dilute hydrochloric acid to remove the amine that was not reacted. Then the raw product was washed by deionized water. The washing process was monitored by the measure of surface tension: if the surface tension of washing water was no longer changed with the times of washing, it denoted that the impurities were removed. Therefore, the purification process could be easily controlled. This method could be extended in the purification of other oil-soluble surfactants. The preparation of N-butyl perfiuorooctanesulfonamide (C8F17SO2NHC4H9) was taken as an example. During the purification of product, the surface tension of washing water was increased to about 53 m

  15. 一种枝杈型含氟季铵盐型阳离子表面活性剂的合成及其性能%Synthesis of Branched Fluorinated Cationic Surfactant and its Surface Tension Properties

    Institute of Scientific and Technical Information of China (English)

    武宏科; 沈海民; 史鸿鑫

    2014-01-01

    A novel branched fluorinated cationic surfactant diethyl-methyl-(2-{4-[3,4,4,4- tetrafluoro-2-(1,2,2,2-tetrafluoro-1-trifluoromethyl-ethyl)-1,3-bis-trifluoromethyl-but-1-enyloxy]-benzenesulfonylamino}-ethyl)-ammonium iodide(IV) was synthesized from ((1,1,1,4,5,5,5-heptafluoro-3-(per-fluoropropan-2-yl)-4-(trifluoromethyl)-pent-2-en-2-yl)oxy) benzene via sulphonating with chlorosulfonic acid, ammonolysis with N,N-diethylethylenediamine, methylation with iodomethane. The yield reaches 45 % and the structures were characterized by FT-IR, 1H-NMR and MS. The target compound was evaluated for its surface tension properties, which the surface tension at critical micelle concentration (CMC) 2.5×10-5 mol×L-1 is 21.0 mN×m-1. The effects of temperature, electrolyte and, the combination with hydrocarbon surfactant were investigated. The results indicate that the prepared branched fluorinated cationic surfactant displays good surfactant performance.%以枝杈型含氟醚(4-全氟-[(1,3-二甲基-2-异丙基)-1-丁烯]氧基苯基醚)为原料,通过磺酰化、胺解和季铵化,得到枝杈型含氟季铵盐型阳离子表面活性剂[N-[4-[全氟-(1,3-二甲基-2-异丙基)-1-丁烯]氧基苯磺酰胺基]乙基二乙基甲基碘化铵,其结构经IR、1H-NMR、MS得到确认;其水溶液的临界胶束浓度(CMC)为2.5×10-5 mol×L-1,此时的表面张力为21.0 mN×m-1通过对温度、电解质以及与碳氢表面活性剂的复配研究发现:随着温度的升高其水溶液的CMC和表面张力呈下降趋势;盐度对其影响不大且具有较好的复配性能。

  16. Fragmentation in Biaxial Tension

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, G H; Archbold, G C; Hurricane, O A; Miller, P L

    2006-06-13

    We have carried out an experiment that places a ductile stainless steel in a state of biaxial tension at a high rate of strain. The loading of the ductile metal spherical cap is performed by the detonation of a high explosive layer with a conforming geometry to expand the metal radially outwards. Simulations of the loading and expansion of the metal predict strain rates that compare well with experimental observations. A high percentage of the HE loaded material was recovered through a soft capture process and characterization of the recovered fragments provided high quality data, including uniform strain prior to failure and fragment size. These data were used with a modified fragmentation model to determine a fragmentation energy.

  17. Tension-filled Governance?

    DEFF Research Database (Denmark)

    Celik, Tim Holst

    Since the crisis-engrossed 1970s, and especially the 1990s, ‘governance’ has become a dominant concern and concept; notably, within particularly political science, a certain diagnosis explicitly or implicitly focused on a shift ‘from government to governance’ has become increasingly popular....... This study examines the governance phenomenon of the post-1970/1990s period from a state-situated and historically informed perspective. Specifically, taking initial analytical departure in an approach of the early 1970s associated with James O’Connor, Jürgen Habermas and Claus Offe focused...... on the statesituated tension-filled functional relationship between legitimation and accumulation, the study both historically and theoretically reworks this approach and reapplies it for the post-1970s/1990s governance period. It asks whether and to what extent governance has served as a distinctive post- 1970s/1990s...

  18. Social and environmental tensions

    DEFF Research Database (Denmark)

    Saito, Moeko; Rutt, Rebecca Leigh; Chhetri, Bir Bahadur Khanal

    2014-01-01

    them, receive payments not only to address inequities but also for resource conservation. Drawing on a case study of a NORAD pilot project in Nepal, this paper investigates how affirmative measures adopted under the project affect different social actors and their perceptions and behaviors in relation......REDD + is a mitigation measure against global climate change that offers payments to developing countries based on the increased volume of forest carbon. It has been argued that affirmative measures should be adopted to ensure that communities, particularly the socially disadvantaged groups among...... to forests. Our case highlights the risk that the mere application of affirmative measures may give rise to difficult social and environmental tensions. Thus, this paper calls for such measures to effectively incorporate local perspectives in their designs and to be reflective, by allowing for regular...

  19. Research on Web Press Tension Control System

    OpenAIRE

    Chen Sheng Jiang; Zhang Chun Feng; Wang Zhong You; Li Qing Lin

    2016-01-01

    Tension control of press is a key and difficult point of the whole machine control. The stand or fall of tension is directly related to the quality of the products. According to the characteristics of the web press tension control, this paper expounds the main factors influencing tension and the purpose of tension control, researches on the tension control principle of web tape, analyzes control rule and control circuit of tension control system, illustrates the advantages of PID control law ...

  20. Tensão superficial dinâmica e ângulo de contato de soluções aquosas com surfatantes em superfícies artificiais e naturais Dynamic surface tension and contact angle of water solutions with spray surfactants in artificial and natural surfaces

    Directory of Open Access Journals (Sweden)

    Cristina A. R. Iost

    2010-08-01

    Full Text Available O trabalho objetivou avaliar o efeito de surfatantes em soluções aquosas sobre a tensão superficial dinâmica e ângulo de contato das gotas em diferentes superfícies: artificiais (lâmina de vidro e de óxido de alumínio e naturais (superfícies adaxiais de folhas de Euphorbia heterophylla, Ipomoea grandifolia e Brachiaria plantaginea. Seis formulações de surfatantes (Antideriva®; Uno®; Pronto 3®; Li-700®; Supersil® e Silwet L-77®, respectivamente nas doses recomendadas do produto comercial (0,050; 0,025; 0,100; 0,250; 0,100 e 0,100 % v v-1 e o dobro delas, foram avaliadas em soluções aquosas. A tensão superficial dinâmica e o ângulo de contato formado sobre as superfícies naturais foram medidos por tensiômetro. Os ângulos de contato formados pelas gotas nas superfícies artificiais foram obtidos por análise de imagens capturadas por uma câmera digital. Os surfatantes influenciam nas propriedades físico-químicas de soluções aquosas. As soluções contendo os surfatantes Silwet L-77® e Supersil®; nas doses de 0,100 e 0,200% v v-1; proporcionaram maiores reduções na tensão superficial dinâmica e menores ângulos de contato das gotas sobre as superfícies artificiais e naturais. Os surfatantes organossiliconados em solução aquosa foram mais eficientes na redução da tensão superficial e proporcionaram maior molhamento de superfícies natural e artificial. Em alvos naturais, essas propriedades obtidas com organossiliconados são dependentes das características de superfície das espécies vegetais.The aim of the work was to evaluate the effect of surfactants in water solutions on dynamic surface tension and contact angle formed by the spray droplets in different surfaces: artificial (glass and aluminum oxide slides and natural (leaves surface of three species of weeds: Euphorbia heterophylla, Ipomoea grandifolia e Brachiaria plantaginea. Were studied six surfactants formulations (AntiderivaTM; UnoTM; Pronto 3TM

  1. Calculating models on surface tension of RE2O3-MgO-SiO2 (RE=La, Nd, Sm, Gd and Y) melts%RE2O3-MgO-SiO2(RE=La,Nd,Sm,Gd和Y)熔体表面张力的计算模型

    Institute of Scientific and Technical Information of China (English)

    吴铖川; 成国光

    2014-01-01

    基于熔体组元离子半径和Butler方程,建立RE2O3−MgO−SiO2(RE=La,Nd,Sm,Gd和Y)熔体表面张力热力学计算模型。本模型利用纯组元的表面张力和摩尔体积以及熔体中各组元阳离子和阴离子半径可以获得E2O3−MgO−SiO2熔体表面张力随熔渣成分和温度的变化规律。计算1873 K La2O3−MgO−SiO2熔体等表面张力线并研究熔体成分对表面张力的影响。1873 K的纯组元La2O3,Gd2O3,Nd2O3和Y2O3的表面张力通过本模型计算分别为686、677、664和541 mN/m。除了Y2O3外,纯稀土氧化物的表面张力随其阳离子磁场强度增加而呈线性减小,而Y2O3的表面张力相对减小更多。表面张力的计算结果与文献数据一致,1873 K本模型平均偏差为1.05%。%A thermodynamic model was developed for determining the surface tension of RE2O3−MgO−SiO2 (RE=La, Nd, Sm, Gd and Y) melts considering the ionic radii of the components and Butler’s equation. The temperature and composition dependence of the surface tensions in molten RE2O3−MgO−SiO2 slag systems was reproduced by the present model using surface tensions and molar volumes of pure oxides, as well as the anionic and cationic radii of the melt components. The iso-surface tension lines of La2O3−MgO−SiO2 slag melt at 1873 K were calculated and the effects of slag composition on the surface tension were also investigated. The surface tensions of La2O3, Gd2O3, Nd2O3 and Y2O3 at 1873 K were evaluated as 686, 677, 664 and 541 mN/m, respectively. The surface tension of pure rare earth oxide melts linearly decreases with increasing cationic field strength, except for Y2O3 oxide, while Y2O3 has a much weaker surface tension. The evaluated results of the surface tension show good agreements with literature data, and the mean deviation of the present model is found to be 1.05% at 1873 K.

  2. Research on Web Press Tension Control System

    Directory of Open Access Journals (Sweden)

    Chen Sheng Jiang

    2016-01-01

    Full Text Available Tension control of press is a key and difficult point of the whole machine control. The stand or fall of tension is directly related to the quality of the products. According to the characteristics of the web press tension control, this paper expounds the main factors influencing tension and the purpose of tension control, researches on the tension control principle of web tape, analyzes control rule and control circuit of tension control system, illustrates the advantages of PID control law adopted in the tension control system, and concludes the influencing factors of paper tape tension control system and the corresponding problems needed to solve in the control.

  3. Longwall AFC chain tension meter

    Energy Technology Data Exchange (ETDEWEB)

    Peter Lugg; Zhiqiang Guan; Bart Pienaar [CRC Mining (Australia)

    2008-02-15

    Evaluation of the downtime statistics of two longwall mines studied as part of the Landmark Automation Project showed that AFC (Armoured Face Conveyor) and BSL (Beam Stage Loader) chain related failures accounted for 27% of all downtime. A chain tension meter was designed, certified Ex ia for use in ERZ0 sections of Australian coal mines and successfully field trialled on a longwall face during production. The dynamic behaviour and unequal sharing of load between the chains were recorded and found to be significant. The changing format of tension distribution around the conveyor as it is loaded was recorded and the implications of the change in the location of the point of minimum tension from tailgate to maingate as the conveyor is unloaded emphasised. The trial was run monitoring AFC chain tensions over a few shifts. The project successfully demonstrated that the measurement of AFC chain tensions on a working face can be achieved reliably.

  4. More than surface tension: femmes in families.

    Science.gov (United States)

    Lev, Arlene Istar

    2008-01-01

    This article raises questions about the lack of scholarly focus on butch/femme couples and their absence in studies of lesbian couples and family-building. In an era of lesbian marriage and lesbian parenting, femme and butch coupling and family-building remain unspoken topics within family studies, including lesbian, gay, bisexual, transgender (LGBT)-specific research. Moving beyond a focus on eroticism within the femme/butch couple, questions about how gender expression impacts other relationships dynamics, including the maintenance of long-term relationships, power and intimacy, domestic chores and child-rearing, are raised. The femme role "homemaking" that is, building and maintaining families, especially needs further exploration.

  5. Bond Tension in Tethered Macromolecules.

    Science.gov (United States)

    Sheiko, Sergei S; Panyukov, Sergey; Rubinstein, Michael

    2011-06-14

    The paper presents scaling analysis of mechanical tension generated in densely branched macromolecules tethered to a solid substrate with a short linker. Steric repulsion between branches results in z-fold amplification of tension in the linker, where z is the number of chain-like arms. At large z ~ 100-1000, the generated tension may exceed the strength of covalent bonds and sever the linker. Two types of molecular architectures were considered: polymer stars and polymer "bottlebrushes" tethered to a solid substrate. Depending on the grafting density, one distinguishes the so-called mushroom, loose grafting, and dense grafting regimes. In isolated (mushroom) and loosely tethered bottlebrushes, the linker tension is by a factor of [Formula: see text] smaller than the tension in a tethered star with the same number of arms z. In densely tethered stars, the effect of interchain distance (d) and number of arms (z) on the magnitude of linker tension is given by f ≅ f0z(3/2)(b/d) for stars in a solvent environment and f ≅ f0z(2) (b/d)(2) for dry stars, where b is the Kuhn length and f0 ≅ kBT/b is intrinsic bond tension. These relations are also valid for tethered bottlebrushes with long side chains. However, unlike molecular stars, bottlebrushes demonstrate variation of tension along the backbone f ≅ f0s z(1/2) / d as a function of distance s from the free end of the backbone. In dense brushes [Formula: see text] with z ≅ 1000, the backbone tension increases from f ≅ f0 = 1 pN at the free end of the backbone (s ≅ b) to its maximum f ≅ zf0 ≅ 1 nN at the linker to the substrate (s ≅ zb).

  6. Giant bullae mimicking tension pneumothorax

    Directory of Open Access Journals (Sweden)

    Ahmet Erbey

    2012-12-01

    Full Text Available Giant bullae may mimic tension pneumothorax radiologicallyso that it may expand completely to hemithorax,increase of radiolucency mediastinal shift, flattening ofdiaphragm and printing on trachea. Sixty one year oldmale patient with giant bullae misdiagnosed as tensionpneumothorax and underwent to tube thoracostomy. Thedifferential diagnosis of giant bullae and tension pneumothoraxmay be confusing. The therapeutic approaches ofthese two radiologically similar entities differ significantly.Thus proper physical assessment and radiological examinationis crucial in the differential diagnosis and computedtomography examination should be performed before theadjustment of therapy. J Clin Exp Invest 2012; 3(4: 548-551Key words: Tension pneumothorax, giant bullae, computedtomography, tube thoracostomy

  7. Local deformation method for measuring element tension in space deployable structures

    Directory of Open Access Journals (Sweden)

    Belov Sergey

    2017-01-01

    Full Text Available The article describes the local deformation method to determine the tension of cord and thin membrane elements in space deployable structure as antenna reflector. Possible measuring instrument model, analytical and numerical solutions and experimental results are presented. The boundary effects on measurement results of metallic mesh reflector surface tension are estimated. The study case depicting non-uniform reflector surface tension is considered.

  8. Direct in situ measurement of specific capacitance, monolayer tension, and bilayer tension in a droplet interface bilayer.

    Science.gov (United States)

    Taylor, Graham J; Venkatesan, Guru A; Collier, C Patrick; Sarles, Stephen A

    2015-10-14

    Thickness and tension are important physical parameters of model cell membranes. However, traditional methods to measure these quantities require multiple experiments using separate equipment. This work introduces a new multi-step procedure for directly accessing in situ multiple physical properties of droplet interface bilayers (DIB), including specific capacitance (related to thickness), lipid monolayer tension in the Plateau-Gibbs border, and bilayer tension. The procedure employs a combination of mechanical manipulation of bilayer area followed by electrowetting of the capacitive interface to examine the sensitivities of bilayer capacitance to area and contact angle to voltage, respectively. These data allow for determining the specific capacitance of the membrane and surface tension of the lipid monolayer, which are then used to compute bilayer thickness and tension, respectively. The use of DIBs affords accurate optical imaging of the connected droplets in addition to electrical measurements of bilayer capacitance, and it allows for reversibly varying bilayer area. After validating the accuracy of the technique with diphytanoyl phosphatidylcholine (DPhPC) DIBs in hexadecane, the method is applied herein to quantify separately the effects on membrane thickness and tension caused by varying the solvent in which the DIB is formed and introducing cholesterol into the bilayer. Because the technique relies only on capacitance measurements and optical images to determine both thickness and tension, this approach is specifically well-suited for studying the effects of peptides, biomolecules, natural and synthetic nanoparticles, and other species that accumulate within membranes without altering bilayer conductance.

  9. Temperature compensation of the SAW yarn tension sensor.

    Science.gov (United States)

    Lu, Wenke; Feng, Yang; Zhu, Changchun; Zheng, Jianli

    2017-04-01

    The objective of this research was to investigate the possibility of the temperature compensation for the surface acoustic wave (SAW) yarn tension sensor. The motivation for this work was prompted by the oscillation frequency of the SAW yarn tension sensor varying with the temperature. In this paper, we deduce the functional relationship between the temperature variation and the oscillation frequency shift caused by the temperature. This functional relationship and the temperature sensor are used to get the oscillation frequency shift caused by the temperature, so that we can use the oscillation frequency shift caused by the temperature to implement the temperature compensation of the SAW yarn tension sensor. In this paper, we also get the relative error of the temperature compensation. The theoretical and experimental results confirm that this temperature compensation method can implement the temperature compensation of the SAW yarn tension sensor. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Droplets on a deformable membrane with uniform and anistropic tension

    Science.gov (United States)

    Schulman, Rafael; Ledesma-Alonso, René; Salez, Thomas; Raphaël, Elie; Dalnoki-Veress, Kari

    We examine the deformation produced by micro-droplets atop thin elastomeric free-standing films. Under the action of surface tension, the droplets deform the membrane thereby forming a bulge. For films with isotropic tension, we measure the contact angles of the droplet and bulge relative to the planar film surrounding the droplet as a function of membrane tension. We find the measured contact angles to be in excellent agreement with a model which features a force balance at the contact line. Experiments are also performed on membranes with anisotropic tension and compared to theory. In this case, droplets are non-spherical and generate significant deformation of the surrounding film which becomes non-planar.

  11. Surface tension investigation and model forecasting of SiO2--Al2 O3--CaO--MgO quaternary mineral wool slag%SiO2--Al2 O3--CaO--MgO四元矿渣棉体系的表面张力测定与模型预报

    Institute of Scientific and Technical Information of China (English)

    彭犇; 唐续龙; 勾立争; 胡一文; 郭敏; 张梅

    2014-01-01

    Surface tension is one of the major parameters for mineral wool production, and it may influence burdening and processing parameter selection. The surface tension of melts for mineral wool production using blast furnace slag as a major material was systematically investigated by experiment measurements and model forecasting. Firstly, a series of surface tension values of SiO2 (40%-- 60%)--Al2 O3 (5%--20%)--CaO(20%--30%)--MgO(5%) quaternary systems were measured, and they showed in the range of 350 to 500 mN·m-1 . Then in combination with data from reports in literature, an artificial neural network (ANN) model was constructed to calculate the surface tension of melts in an extension system of SiO2 (35%--60%)--Al2 O3 (5%--20%)--CaO(20%--45%)--MgO(0-- 10%). The average error of the developed model is 9. 32%, proving a higher accuracy for predicting the surface tension of those melts in the extension system.%表面张力是矿物棉生产的重要参数,直接影响到配料和工艺参数的选择.通过实验测量并建立模型预报系统研究了以高炉渣为主要原料制备矿物棉时熔体的表面张力.首先测量了SiO2(40%~60%)- Al2 O3(5%~20%)- CaO(20%~30%)-MgO(5%)四元系的表面张力,其值处于350~500 mN·m-1之间;然后结合文献报道的表面张力数据,利用人工神经网络技术建立了SiO2(35%~60%)-Al2 O3(5%~20%)-CaO(20%~45%)-MgO(0~10%)四元渣系的表面张力预报模型.该模型对成分范围内的表面张力预报平均误差为9.32%,预报精度较高,可以预报矿物棉熔体成分范围内的表面张力.

  12. 低表面张力ASA改性瓜尔胶表面施胶剂的制备及其应用%Preparation and Application of Surface Sizing Agent with Low Surface Tension of Guar Gum Modified by ASA

    Institute of Scientific and Technical Information of China (English)

    杨晓武; 沈一丁; 李培枝; 薛贝

    2012-01-01

    采用烯基琥珀酸酐(ASA)对瓜尔胶原粉进行改性来制备一种环境友好型表面施胶剂,对纸张进行表面施胶并对其施胶效果进行了测定。讨论了瓜尔胶与ASA的用量比例、反应温度及反应时间等对施胶效果的影响,同时采用红外光谱(FT-IR)、X射线衍射(XRD)和动态接触角(DCA)等测试手段对其结构、性能和应用效果进行了表征。结果表明,当瓜尔胶原粉与ASA比例为7:1,反应温度为60℃,反应时间为10h,在瓜尔胶分子上成功引入疏水性长链,改性瓜尔胶表面施胶浓度为2.5%时,纸张的施胶度可以达到54S,动态接触角可达118°以上。%In order to prepare a kind of environment-friendly surface sizing agent, the guar gum was modified by alkenyl succinic anhydride (ASA), and the surface sizing effect of the modified guar gum was studied. ~ae effect on surface sizing of the reactant ratio, reaction temperature and reaction time were discussed, and the structure, performance and application effect were characterized by the infrared spectrum (FT-IR), X-ray diffraction (XRD), dynamic contact angle (DCA) and so on. ]-he results showed that when the ratio of the guar gum and ASA was 7:1, reaction temperature was 60~C, reaction time was 10 hours, the hydrophobic long chain was introduced onto the guar gum successfiaUy. As the dosage of modified guar gum was 2.5%, the sizing degree was up to 54 seconds, and the dynamic contact angle was more than 118°.

  13. Surface chemistry theory and applications

    CERN Document Server

    Bikerman, J J

    2013-01-01

    Surface Chemistry Theory and Applications focuses on liquid-gas, liquid-liquid, solid-gas, solid-liquid, and solid-solid surfaces. The book first offers information on liquid-gas surfaces, including surface tension, measurement of surface tension, rate of capillarity rise, capillary attraction, bubble pressure and pore size, and surface tension and temperature. The text then ponders on liquid-liquid and solid-gas surfaces. Discussions focus on surface energy of solids, surface roughness and cleanness, adsorption of gases and vapors, adsorption hysteresis, interfacial tension, and interfacial t

  14. Effects of interplay of nanoparticles, surfactants and base fluid on the interfacial tension of nanocolloids

    CERN Document Server

    Harikrishnan, A R; Agnihotri, PK; Gedupudi, Sateesh; Das, Sarit K

    2016-01-01

    A systematically designed study has been conducted to understand and clearly demarcate the degree of contribution by the constituting elements to the surface tension of nanocolloids. The effects of elements such as surfactants, particles and the combined effects of these on the interfacial tension of these complex fluids are studied employing pendant drop shape analysis method by fitting Young Laplace equation. Only particle has shown considerable increase in surface tension with particle concentration in a polar medium like DI water whereas only marginal effect particles on surface tension in weakly polar mediums like glycerol and ethylene glycol. Such behaviour has been attributed to the enhanced desorption of particles to the interface and a mathematical framework has been derived to quantify this. Combined particle and surfactant effect on surface tension of complex nanofluid system showed a decreasing behaviour with respect to the particle and surfactant concentration with a considerably feeble effect of...

  15. Cosmic Strings with Small Tension

    CERN Document Server

    Halyo, Edi

    2009-01-01

    We describe cosmic F--term strings with exponentially small tension which are D3 branes wrapped on deformed $A_3$ singularities. We show that brane instanton effects which can be calculated after a geometric transition give rise to an exponentially small volume for the node on which the D3 branes wrap leading to a string with small tension. We generalize our description to the case of non--Abelian cosmic strings and argue that these strings are stable against monopole--anti monopole pair creation.

  16. Measurement of the angle of superficial tension by images

    Science.gov (United States)

    Yanez M., Javier; Alonso R., Sergio

    2006-02-01

    When a liquid is deposited on a surface, this one form a certain angle with respect to the surface, where depending on its value, it will conclude that so hard it is his adhesion with the surface. By means of the analysis of images we looked for to measure this angle of superficial tension. In order to make this measurement, we propose a technique by means of projective transformations and one method of regression to estimation parameters to conic fitting.

  17. Fatigue Behaviour and Life Assessment of Jute-epoxy Composites under Tension-Tension Loading

    Science.gov (United States)

    Padmaraj, N. H.; Chethan, K. N.; Pavan; Onkar, Anand

    2017-08-01

    The present study involves fabrication and fatigue life assessment of multi-layered, woven jute fibres with epoxy matrix composites. Jute fabric were treated with 1N sodium hydroxidesolution for a duration of 6 hours. Alkali treatment was done to modify internal structure as well as surface properties of fibre. Laminates were fabricated by laying up multi layered woven jute fabric at varying angle [0-900/ (±450)2/0-900]. Vacuum bagging method was used to reduce the void content and thus increase the quality of composites. Tension-Tension fatigue tests were performed with a constant fatigue stress ratio (R=0.1) and results obtained from the tests were used to plot S-N Curve. A model based on power law equation was used for curve fitting.

  18. AUTOGENIC THERAPY IN TENSION HEADACHE

    OpenAIRE

    Amruthraj, Brunda; Mishra, H.; Kumaraiah, V.

    1987-01-01

    SUMMARY Ten subjects diagnosed as Psychalgia were taken for study. A multiple baseline design was adapted and clients were subjected to 30 sessions of autogenic training. They were assessed using physiological (EMG and thermal change) and behavioural measures (Visual analogue scale and behavioural symptom checklist). Findings revealed autogenic therapy to be effective in reducing tension headache.

  19. Tension type headaches: a review

    African Journals Online (AJOL)

    23. Epidemiology. A wide variation in the prevalence of tension-type headaches .... intensity tending to be less in the morning, building up after noon, and reducing ... with a change in position or the start of Valsalva-like sneezing. • Associated ...

  20. Abolishing the maximum tension principle

    CERN Document Server

    Dabrowski, Mariusz P

    2015-01-01

    We find the series of example theories for which the relativistic limit of maximum tension $F_{max} = c^2/4G$ 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.

  1. 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.

  2. CALCULATION OF TENSION FORCE OF BELT CONVEYOR

    Directory of Open Access Journals (Sweden)

    Ismet Ibishi

    2012-12-01

    Full Text Available 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 mechanization, so forces on the rope passing through pulley there has to dominate the friction coefficient. All this process is related to economy of transportationmechanism.

  3. Fatigue growth of a surface crack in a V-shaped notched round bar under cyclic tension%反复张力下V形切口圆条的表面裂纹的疲劳扩展

    Institute of Scientific and Technical Information of China (English)

    Devi CHANDRA; Judha PURBOLAKSONO; Yusoff NUKMAN; Haw-ling LIEW; Singh RAMESH; Mohsen-abdel HASSAN

    2014-01-01

    This paper presents modeling results for fatigue crack growths of a semi-elliptical surface crack in a V-shaped notched round bar under uniform cyclic tension. All the analyses were carried out by using a software package featuring the boundary element method. The J-integral technique was used to compute the stress intensity factors (SIFs), and the NASGRO crack growth rate was chosen to simulate the fatigue crack growths. Mechanical and fracture properties of AZ-6A-T5 magnesium alloy were used for our analysis. Crack shape evolutions for different crack aspect ratios and the corresponding SIFs may be correlated to study the behavior of crack growths. An unstable crack growth was observed when the evolving crack aspect ratio was between 0.6 and 0.7. Careful consideration should be taken if the cylinder contains a defect which has a straight shape on the crack front or a smaller crack aspect ratio.%研究目的:在相同的反复张力下,研究V形切口圆条表面裂纹的疲劳扩展规律。  研究方法:1.构建V形切口圆条模型(图1),基于线性二次元将模型表面离散成一个个网格点(图2);2.以AZ-6A-T5镁合金为例,利用J积分计算应力强度因数,利用NASGRO裂纹增长率模拟裂纹的疲劳扩展;3.通过研究不同的裂纹纵横比和对应的应力强度因数之间的相关性来研究裂纹的扩展。  重要结论:1.在裂纹扩展时裂纹纵横比的初始值对断裂形状的发展有重要影响;2.裂纹纵横比对疲劳负荷寿命的作用比缺口半径更加明显;3.当裂纹前缘演变成一条直线形时可观察到不稳定的裂纹扩展;4.裂纹深度一定时,断裂纵横比越小,疲劳负荷寿命越短;5.当裂纹纵横比为0.6-0.7时,出现了不稳定的裂纹扩展。

  4. Interfacial tension controlled W/O and O/W 2-phase flows in microchannel

    NARCIS (Netherlands)

    Shui, Lingling; van den Berg, Albert; Eijkel, Jan C.T.

    2009-01-01

    In microfluidic systems, interfacial tension plays a predominant role in determining the two-phase flow behavior due to the high surface area to volume ratio. We investigated the influence of both solid-liquid (sigma(SL)) and liquid-liquid (sigma(LL)) interfacial tensions on water-oil two-phase

  5. Line tension and reduction of apparent contact angle associated with electric double layers

    CERN Document Server

    Dörr, Aaron

    2014-01-01

    The line tension of an electrolyte wetting a non-polar substrate is computed analytically and numerically. The results show that, depending on the value of the apparent contact angle, positive or negative line tension values may be obtained. Furthermore, a significant difference between Young's contact angle and the apparent contact angle measured several Debye lengths remote from the three-phase contact line occurs. When applying the results to water wetting highly charged surfaces, line tension values of the same order of magnitude as found in recent experiments can be achieved. Therefore, the theory presented may contribute to the understanding of line tension measurements and points to the importance of the electrostatic line tension. Being strongly dependent on the interfacial charge density, electrostatic line tension is found to be tunable via the pH value of the involved electrolyte. As a practical consequence, the stability of nanoparticles adsorbed at fluid-fluid interfaces is predicted to be depend...

  6. The Yarn Curve and Tension in Rotor Spinning

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The effective way of finding the yarn curve shape and tension of OE(open end) yarn inside the rotor is carried out and treated by dividing the yarn curve into two parts, from which the trajectory of the yarn sliding on the navel surface is also obtained. It is pointed out that the yarn curve shape and tension will both fluctuate with the trajectory's revolving cycle inside the rotor. However, the fluctuation is not too great, so the motion can still be regarded as approximately steady for dynamic analysis.

  7. 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....

  8. 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.

  9. Mass spectrometry analysis of surface tension reducing substances produced by a pah-degrading Pseudomonas citronellolis strain Análise por espectrometria de massa de substâncias redutoras da tensão superficial produzidas por uma cepa de Pseudomonas citronellolis degradadora de hidrocarbonetos aromáticos policíclicos

    Directory of Open Access Journals (Sweden)

    Rodrigo J. S. Jacques

    2008-06-01

    Full Text Available In this work we investigated the structure of the iron-stimulated surface tension reducing substances produced by P. citronellolis 222A isolated from a 17-years old landfarming used for sludge treatment in petrochemical industries and oil refinery. Its mass spectrum differs from P. aeruginosa spectrum, indicating that the surface tension reducing substances produced by P. citronellolis can be a new kind of biosurfactant.Neste trabalho é apresentado um estudo a respeito da análise da estrutura de substâncias redutoras de tensão superficial produzidas por Pseudomonas citronellolis 222A estimulado pela presença de ferro. Esta bactéria foi isolada de um solo que há 17 anos vem sendo utilizado para o tratamento de borra oleosa proveniente da indústria petroquímica e de refinaria de petróleo. O espectro de massa difere do espectro de P. aeruginosa, indicando que as substâncias redutoras de tensão superficial produzidas por P. citronellolis podem ser um novo tipo de biosurfactante.

  10. Tension fracture behaviors of welded joints in X70 steel pipeline

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The surface of welded joints in X70 steel pipeline was processed by laser shock wave, its mechanical behaviors of tension fracture were analyzed with tension test,and the fracture morphologies and the distributions of chemical element were observed with scanning electron microscope and energy dispersive spectrum,respectively.The experimental results show that the phenomenon of grain refinement occurs in the surface of welded joints in X70 steel pipeline after the laser shock processing,and compressive re...

  11. 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.

  12. Development of DPD coarse-grained models: From bulk to interfacial properties

    Science.gov (United States)

    Solano Canchaya, José G.; Dequidt, Alain; Goujon, Florent; Malfreyt, Patrice

    2016-08-01

    A new Bayesian method was recently introduced for developing coarse-grain (CG) force fields for molecular dynamics. The CG models designed for dissipative particle dynamics (DPD) are optimized based on trajectory matching. Here we extend this method to improve transferability across thermodynamic conditions. We demonstrate the capability of the method by developing a CG model of n-pentane from constant-NPT atomistic simulations of bulk liquid phases and we apply the CG-DPD model to the calculation of the surface tension of the liquid-vapor interface over a large range of temperatures. The coexisting densities, vapor pressures, and surface tensions calculated with different CG and atomistic models are compared to experiments. Depending on the database used for the development of the potentials, it is possible to build a CG model which performs very well in the reproduction of the surface tension on the orthobaric curve.

  13. Tension-compression asymmetry and twin boundaries spacings effects in polycrystalline Ni nanowires

    Science.gov (United States)

    Zhang, Feng; Zhou, Jianqiu

    2016-07-01

    Tension-compression asymmetry could be a notable feature in many nanocrystalline (NC) materials. The scientific and practical research on the tension-compression asymmetry may play an important role of improving the mechanical behavior of NC materials. Using large-scale molecular dynamics (MD) simulations at the strain rate of 109 s-1, both tension and compression tests are complemented in twin-structural polycrystalline Ni nanowires (NWs). The MD simulation suggests that twin boundaries spacing (TBS) has an interesting effect on the tension-compression asymmetry. For NW (radius = 9 nm) with different TBSs, the flow stresses are totally higher under compression than under tension. The asymmetry gets a minimum value at a particular TBS. Such results can be explained by the interplay of the work of dislocations mechanism under various TBSs and the free surface in NWs.

  14. HILBERTIAN APPROACH FOR UNIVARIATE SPLINE WITH TENSION

    Institute of Scientific and Technical Information of China (English)

    A.Bouhamidi

    2001-01-01

    In this work,a new approach is proposed for constructing splines with tension.The basic idea is in the use of distributions theory,which allows us to define suitable Hilbert spaces in which the tension spline minimizes some energy functional.Classical orthogonal conditions and characterizations of the spline in terms of a fundamental solution of a differential operator are provided.An explicit representation of the tension spline is given.The tension spline can be computed by solving a linear system.Some numerical examples are given to illustrate this approach.

  15. Constraining brane tension using rotation curves of galaxies

    CERN Document Server

    Garcia-Aspeitia, Miguel A

    2015-01-01

    We present in this work a study of brane theory phenomenology focusing on the brane tension parameter, which is the main observable of the theory. We show the modifications steaming from the presence of branes in the rotation curves of spiral galaxies for three well known DM density profiles: the pseudo isothermal (PISO), Navarro-Frenk-White (NFW) and Burkert dark matter density profiles. We estimate the brane tension parameter using a sample of high resolution observed rotation curves of low surface brightness spiral galaxies for the three density profiles. Also, the fittings using the brane theory model of the rotation curves are compared with standard Newtonian models. We found that NFW model prefers lower values of the brane tension parameter, on the average $\\lambda \\sim 0.73\\times 10^{-3}$ eV$^4$, therefore showing clear brane effects. Burkert case does prefer higher values of the tension parameter, on the average $\\lambda \\sim 0.93$ eV$^4$, i.e., negligible brane effects. Whereas PISO is an intermediat...

  16. [Tension pneumomediastinum and tension pneumothorax following tracheal perforation during cardiopulmonary resuscitation].

    Science.gov (United States)

    Buschmann, C T; Tsokos, M; Kurz, S D; Kleber, C

    2015-07-01

    Tension pneumothorax can occur at any time during cardiopulmonary resuscitation (CPR) with external cardiac massage and invasive ventilation either from primary or iatrogenic rib fractures with concomitant pleural or parenchymal injury. Airway injury can also cause tension pneumothorax during CPR. This article presents the case of a 41-year-old woman who suffered cardiopulmonary arrest after undergoing elective mandibular surgery. During CPR the upper airway could not be secured by orotracheal intubation due to massive craniofacial soft tissue swelling. A surgical airway was established with obviously unrecognized iatrogenic tracheal perforation and subsequent development of tension pneumomediastinum and tension pneumothorax during ventilation. Neither the tension pneumomediastinum nor the tension pneumothorax were decompressed and accordingly resuscitation efforts remained unsuccessful. This case illustrates the need for a structured approach to resuscitate patients with ventilation problems regarding decompression of tension pneumomediastinum and/or tension pneumothorax during CPR.

  17. 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...

  18. Efeitos de surfatantes sobre a tensão superficial e a área de molhamento de soluções de glyphosate sobre folhas de tiririca Effects of surfactants on surface tension and foliar wetting solutions of glyphosate over purple nutsedge leaves

    Directory of Open Access Journals (Sweden)

    Cristiane G. de Mendonça

    1999-12-01

    Full Text Available Com o objetivo de avaliar a eficiência da agregação de surfatantes ao herbicida glyphosate analisou-se a tensão superficial de diferentes soluções de pulverização contendo o hebicida e o surfatante, e a área de molhamento destas soluções nas folhas de Cyperus rotundus L.. Foram desenvolvidos métodos para avaliação da tensão superficial e da área de molhamento. Para analisar a tensão fez-se pesagens das gotas formadas na extremidade de uma bureta, com os seguintes tratamentos combinados de forma fatorial (3 x 5 x 11: 3 surfatantes (Extravon, Aterbane e Silwet L-77, 5 concentrações do herbicida, produto comercial Roundup (0; 1; 2; 3,5 e 5 % e 11 concentrações de cada surfatantes (0; 0,005; 0,01; 0,02; 0,05; 0,1; 0,2; 0,5; 1; 2 e 3,5 %, num total de 165 tratamentos. Para avaliar a área de molhamento nas folhas de tiririca aplicou-se gotas de 0,48 .l. Os dados foram ajustados pelo modelo de Mitscherlich e, observou-se que para o surfatante Extravon que a eficiência decrescia gradativamente a medida em que aumentava a concentração do herbicida; para o Aterbane a eficiência foi reduzida apenas em baixas concentrações; já o surfatante Silwet L-77 apresentou eficiência bem superior aos demais e sua eficiência foi pouco alterada com a adição herbicida. Houve uma correlação positiva entre área de molhamento e tensão superficial. Concluiu-se, ainda, que não basta um surfatante reduzir a tensão superficial da água destilada, para que possa ser recomendado seu uso agrícola, assim, o surfatante deve ser submetido a testes preliminares com os defensivos em que serão conjugados para posterior recomendação.This research was undertaken to develop methods to evaluate the surface tension and foliar wetting of surfactant added in herbicide. It used three surfactants (Extravon, Aterbane and Silwet, five concentration of herbicide and eleven surfactant concentrations each. Surface tension and foliar wetting were evaluated by

  19. Effects of emulsifier and co-emulsifier on the particle diameter and surface tension of emulsion in water of emamectin benzoate%乳化剂和共乳化剂对甲维盐水乳剂乳液稳定性的影响

    Institute of Scientific and Technical Information of China (English)

    范福玉; 郭瑞峰; 黄彬彬; 黄珍珠; 吴祖建; 吴刚

    2011-01-01

    在筛选出合适的乳化剂和共乳化剂的基础上,研究了乳化剂亲水亲油平衡值(HLB)、含量以及共乳化剂含量对1%甲氨基阿维菌素苯甲酸盐水乳剂乳液体系稳定性的影响,以及乳化剂在54℃热贮2周的稳定性.结果表明,乳化剂的HLB可以为水乳剂的乳液稳定性提供参考依据,乳液的粒径和表面张力随着乳化剂含量的升高而减小,当乳化剂含量增大到一定程度后,粒径和表面张力开始趋于稳定.共乳化剂对水乳剂的粒径没有太大影响,但可以显著降低水乳剂的表面张力,增强体系的稳定性.水乳剂乳液粒径和表面张力在一定范围内可以反映出乳液体系的稳定性,当粒径和表面张力变小时,乳化剂HLB、含量或共乳化剂含量能够满足热贮稳定性,则此时乳化剂或共乳化剂种类及含量为最佳.%Based on the successful screening for the optimal emulsifiers and co-emulsifiers, the effects of hydrophile lipophile balance (HLB) values of emulsifiers and the concentrations of emulsifiers and co-emulsifiers on the stability of 1% emulsion in water (EW) of emamectin benzoate were studied at 54 ℃ for two weeks. In addition, the stability of emulsifiers was studied. The results showed that the stability of the latex was related to the HLB values of the emulsifiers. The particle diameter and surface tension of the EW decreased corresponding to the increase of the concentration of emulsifier, but particle diameter and surface tension of the 1% emamectin benzoate EW tended to be stable whether the concentration of the emulsifiers increased or not at a higher concentra tion. No significant effect of co-emulsifiers on the particle diameter of the EW was found. However, co-emulsifiers could increase the stability of the 1% emamectin benzoate EW by decreasing surface tension. The results indicated that the stability of the 1% emamectin benzoate Ew could be reflected by particle diameter and surface

  20. 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.