Reaction Dynamics at Liquid Interfaces

NASA Astrophysics Data System (ADS)

Benjamin, Ilan

2015-04-01

The liquid interface is a narrow, highly anisotropic region, characterized by rapidly varying density, polarity, and molecular structure. I review several aspects of interfacial solvation and show how these affect reactivity at liquid/liquid interfaces. I specifically consider ion transfer, electron transfer, and SN2 reactions, showing that solvent effects on these reactions can be understood by examining the unique structure and dynamics of the liquid interface region.

Properties of Wheat-Straw Boards with Frw Based on Interface Treatment

NASA Astrophysics Data System (ADS)

Zhu, X. D.; Wang, F. H.; Liu, Y.

This paper explored the effect of MDI, UF and FRW content on the mechanical and fire retardant property of straw based panels with surface alkali liquor processing. In order to manufacture the straw based panel with high quality, low toxic and fire retardant, the interface of wheat-straw was treated with alkaline liquid, and the orthogonal test was carried out to optimize the technical parameters. The conductivity and diffusion coefficient K of the straw material after alkaline liquid treatment increased obviously. This indicated that alkaline liquid treatment improved the surface wet ability of straw, which is helpful for the infiltration of resin. The results of orthogonal test showed that the optimized treating condition was alkaline liquid concentration as 0.4-0.8%, alkaline dosage as 1:2.5-1:4.5, alkalinetreated time as 12h-48 h.The physical and mechanical properties of wheat-straw boards after treated increased remarkably and it could satisfy the national standard. The improvement of the straw surface wet ability is helpful to the forming of chemical bond. Whereas the variance analysis of the fire retardant property of straw based panel showed that TTI, pkHRR and peak value appearance time were not affected by the MDI, UF and FRW content significantly. The results of orthogonal test showed that the optimized processing condition was MDI content as 3%, UF resin content as 6% and the FRW content as 10%.

Slippage on a particle-laden liquid-gas interface in textured microchannels

NASA Astrophysics Data System (ADS)

Gaddam, Anvesh; Agrawal, Amit; Joshi, Suhas S.; Thompson, Mark C.

2018-03-01

Despite numerous investigations in the literature on slip flows in textured microchannels, experimental results were seldom in agreement with the theory. It is conjectured that contamination of the liquid-gas interface by impurities might be one of the sources of this discrepancy. However, the effect of impurities on slippage at the liquid-gas interface is neither understood nor previously reported. To this end, this work presents numerical investigation on the flow past a liquid-gas interface embedded with solid particles in textured microchannels. Initially, we present numerical simulations past transverse ribs with cylindrical particles on the liquid-gas interface. A reduction in effective slip length (or slip loss) with respect to the particle-free interface as a function of gas fraction, constriction ratio, and particle position was quantified. A significant slip loss (˜20-80%) was induced, owing to acceleration-deceleration cycles experienced by the liquid advecting across the particle-laden liquid-gas interface. Even a small number of solid particles adsorbed on a liquid-gas interface were shown to reduce the effective slip length considerably. This renders a textured microchannel with the particle-laden interface to be ineffective as compared to a completely wetted textured microchannel under certain conditions. Furthermore, a flow past two bi-dimensional textures, viz. posts and holes, with their interfaces embedded with spherical particles was also simulated. Our results show that texture configurations with an unbounded liquid-gas interface can mitigate the detrimental effects of particles adsorbed at the interface. The results presented here will help guide in designing efficient textured surfaces in future.

PREFACE: Functionalized Liquid Liquid Interfaces

NASA Astrophysics Data System (ADS)

Girault, Hubert; Kornyshev, Alexei A.; Monroe, Charles W.; Urbakh, Michael

2007-09-01

Most natural processes take place at interfaces. For this reason, surface science has been a focal point of modern research. At solid-liquid interfaces one can induce various species to adsorb or react, and thus may study interactions between the substrate and adsorbates, kinetic processes, optical properties, etc. Liquid-liquid interfaces, formed by immiscible liquids such as water and oil, have a number of distinctive features. Both sides of the interface are amenable to detailed physical and chemical analysis. By chemical or electrochemical means, metal or semiconductor nanoparticles can be formed or localised at the interface. Surfactants can be used to tailor surface properties, and also to place organic molecular or supermolecular constructions at the boundary between the liquids. Electric fields can be used to drive ions from one fluid to another, or even change the shape of the interface itself. In many cases, both liquids are optically transparent, making functionalized liquid-liquid interfaces promising for various optical applications based on the transmission or reflection of light. An advantage common to most of these systems is self-assembly; because a liquid-liquid interface is not mechanically constrained like a solid-liquid interface, it can easily access its most stable state, even after it has been driven far from equilibrium. This special issue focuses on four modes of liquid-liquid interfacial functionalization: the controlled adsorption of molecules or nanoparticles, the formation of adlayers or films, electrowetting, and ion transfer or interface-localized reactions. Interfacial adsorption can be driven electrically, chemically, or mechanically. The liquid-liquid interface can be used to study how anisotropic particles orient at a surface under the influence of a field, how surfactants interact with other adsorbates, and how nanoparticles aggregate; the transparency of the interface also makes the chirality of organic adsorbates amenable to optical study. Film formation goes a step beyond adsorption; some surfactants form monolayers or multilayers at the interface. A polymer microfilm or a polymer-particle matrix can be synthesized at the liquid-liquid boundary. Such films exhibit unique adsorption and ion-intercalation properties of their own. Electrowetting refers broadly to the phenomenon in which an applied voltage modulates the shape of a liquid-liquid interface, essentially by altering the surface tension. Electric fields can be used to induce droplets on solid substrates to change shape, or to affect the structure of liquid-liquid emulsions. Various chemical reactions can be performed at the liquid-liquid boundary. Liquid-liquid microelectrodes allow detailed study of ion-transfer kinetics at the interface. Photochemical processes can also be used to control the conformations of molecules adsorbed at the interface. But how much precise control do we actually have on the state of the interfacial region? Several contributions to this issue address a system which has been studied for decades in electrochemistry, but remains essentially unfamilar to physicists. This is the interface between two immiscible electrolytic solutions (ITIES), a progressing interdisciplinary field in which condensed-matter physics and physical chemistry meet molecular electrochemistry. Why is it so exciting? The reason is simple. The ITIES is chargeable: when positioned between two electrodes it can be polarized, and back- to-back electrical double layers form on both sides of the liquid-liquid interface. Importantly, the term immiscible refers not only to oil and water but also to the electrolytes. Inorganic electrolytes, such as alkali halides, tend to stay in water, whereas organic electrolytes, such as tetrabutylammonium tetraphenylborate, stay in oil. This behaviour arises because energies of the order of 0.2-0.3 eV are needed to drive ions across the interface. As long as these free energies of transfer are not exceeded by the external potential bias, the ITIES works as an 'electrode'; there is no traffic of ions across it. Thus the interface can sustain fields of the order of 106 V/cm, which are localized in a nanoscopic layer near the interface. This gives many new options for building various kinds of electrically tunable self assembled moloecular devices. Through the years, ITIES have been considered by electrochemists as a popular biomimetic model system, or for studies of interfacial reaction kinetics; ITIES were also used in industrial phase-transfer catalysis. Recently, this system has opened up new options for nano-scale engineering of functional assemblies (for dense information storage, efficient energy conversion, light-harvesting, and miniaturized sensors), which justifies its presentation in this issue.

Real Space Imaging of Nanoparticle Assembly at Liquid-Liquid Interfaces with Nanoscale Resolution.

PubMed

Costa, Luca; Li-Destri, Giovanni; Thomson, Neil H; Konovalov, Oleg; Pontoni, Diego

2016-09-14

Bottom up self-assembly of functional materials at liquid-liquid interfaces has recently emerged as method to design and produce novel two-dimensional (2D) nanostructured membranes and devices with tailored properties. Liquid-liquid interfaces can be seen as a "factory floor" for nanoparticle (NP) self-assembly, because NPs are driven there by a reduction of interfacial energy. Such 2D assembly can be characterized by reciprocal space techniques, namely X-ray and neutron scattering or reflectivity. These techniques have drawbacks, however, as the structural information is averaged over the finite size of the radiation beam and nonperiodic isolated assemblies in 3D or defects may not be easily detected. Real-space in situ imaging methods are more appropriate in this context, but they often suffer from limited resolution and underperform or fail when applied to challenging liquid-liquid interfaces. Here, we study the surfactant-induced assembly of SiO2 nanoparticle monolayers at a water-oil interface using in situ atomic force microscopy (AFM) achieving nanoscale resolved imaging capabilities. Hitherto, AFM imaging has been restricted to solid-liquid interfaces because applications to liquid interfaces have been hindered by their softness and intrinsic dynamics, requiring accurate sample preparation methods and nonconventional AFM operational schemes. Comparing both AFM and grazing incidence X-ray small angle scattering data, we unambiguously demonstrate correlation between real and reciprocal space structure determination showing that the average interfacial NP density is found to vary with surfactant concentration. Additionally, the interaction between the tip and the interface can be exploited to locally determine the acting interfacial interactions. This work opens up the way to studying complex nanostructure formation and phase behavior in a range of liquid-liquid and complex liquid interfaces.

Structural ordering at solid-liquid interfaces in Al-Sm system: A molecular-dynamics study

DOE PAGES

Sun, Yang; Zhang, Feng; Ye, Zhuo; ...

2016-07-12

The structural ordering at solid-liquid interfaces far from equilibrium is studied with molecular dynamics simulations for the Al-Sm system. Using the van-Hove self-correlation function as the criterion to identify attachment/detachment events that occur at the interface, we are able to determine the time-dependent interface position, and characterize the detailed interfacial structure ordering surrounding the attached atoms. For the interface between an undercooled Al90Sm10 liquid and a metastable cubic structure, the solid induces the crystalline order of the cubic phase in the liquid layers, promoting the continuous growth of the crystal phase. When the same liquid is put in contact withmore » f.c.c. Al, Sm from the liquid can still attach to the solid interface despite its insolubility in the Al lattice. Non-f.c.c. order is revealed surrounding the attached Sm atoms. Lastly, we show that the local structure ordering at interface is highly correlated to solid packing and liquid ordering.« less

Water at surfaces with tunable surface chemistries

NASA Astrophysics Data System (ADS)

Sanders, Stephanie E.; Vanselous, Heather; Petersen, Poul B.

2018-03-01

Aqueous interfaces are ubiquitous in natural environments, spanning atmospheric, geological, oceanographic, and biological systems, as well as in technical applications, such as fuel cells and membrane filtration. Where liquid water terminates at a surface, an interfacial region is formed, which exhibits distinct properties from the bulk aqueous phase. The unique properties of water are governed by the hydrogen-bonded network. The chemical and physical properties of the surface dictate the boundary conditions of the bulk hydrogen-bonded network and thus the interfacial properties of the water and any molecules in that region. Understanding the properties of interfacial water requires systematically characterizing the structure and dynamics of interfacial water as a function of the surface chemistry. In this review, we focus on the use of experimental surface-specific spectroscopic methods to understand the properties of interfacial water as a function of surface chemistry. Investigations of the air-water interface, as well as efforts in tuning the properties of the air-water interface by adding solutes or surfactants, are briefly discussed. Buried aqueous interfaces can be accessed with careful selection of spectroscopic technique and sample configuration, further expanding the range of chemical environments that can be probed, including solid inorganic materials, polymers, and water immiscible liquids. Solid substrates can be finely tuned by functionalization with self-assembled monolayers, polymers, or biomolecules. These variables provide a platform for systematically tuning the chemical nature of the interface and examining the resulting water structure. Finally, time-resolved methods to probe the dynamics of interfacial water are briefly summarized before discussing the current status and future directions in studying the structure and dynamics of interfacial water.

Effect of Schmidt number on mass transfer across a sheared gas-liquid interface in a wind-driven turbulence.

PubMed

Takagaki, Naohisa; Kurose, Ryoichi; Kimura, Atsushi; Komori, Satoru

2016-11-14

The mass transfer across a sheared gas-liquid interface strongly depends on the Schmidt number. Here we investigate the relationship between mass transfer coefficient on the liquid side, k L , and Schmidt number, Sc, in the wide range of 0.7 ≤ Sc ≤ 1000. We apply a three-dimensional semi direct numerical simulation (SEMI-DNS), in which the mass transfer is solved based on an approximated deconvolution model (ADM) scheme, to wind-driven turbulence with mass transfer across a sheared wind-driven wavy gas-liquid interface. In order to capture the deforming gas-liquid interface, an arbitrary Lagrangian-Eulerian (ALE) method is employed. Our results show that similar to the case for flat gas-liquid interfaces, k L for the wind-driven wavy gas-liquid interface is generally proportional to Sc -0.5 , and can be roughly estimated by the surface divergence model. This trend is endorsed by the fact that the mass transfer across the gas-liquid interface is controlled mainly by streamwise vortices on the liquid side even for the wind-driven turbulence under the conditions of low wind velocities without wave breaking.

Effect of Schmidt number on mass transfer across a sheared gas-liquid interface in a wind-driven turbulence

PubMed Central

Takagaki, Naohisa; Kurose, Ryoichi; Kimura, Atsushi; Komori, Satoru

2016-01-01

The mass transfer across a sheared gas-liquid interface strongly depends on the Schmidt number. Here we investigate the relationship between mass transfer coefficient on the liquid side, kL, and Schmidt number, Sc, in the wide range of 0.7 ≤ Sc ≤ 1000. We apply a three-dimensional semi direct numerical simulation (SEMI-DNS), in which the mass transfer is solved based on an approximated deconvolution model (ADM) scheme, to wind-driven turbulence with mass transfer across a sheared wind-driven wavy gas-liquid interface. In order to capture the deforming gas-liquid interface, an arbitrary Lagrangian-Eulerian (ALE) method is employed. Our results show that similar to the case for flat gas-liquid interfaces, kL for the wind-driven wavy gas-liquid interface is generally proportional to Sc−0.5, and can be roughly estimated by the surface divergence model. This trend is endorsed by the fact that the mass transfer across the gas-liquid interface is controlled mainly by streamwise vortices on the liquid side even for the wind-driven turbulence under the conditions of low wind velocities without wave breaking. PMID:27841325

Self-diffusion Coefficient and Structure of Binary n-Alkane Mixtures at the Liquid-Vapor Interfaces.

PubMed

Chilukoti, Hari Krishna; Kikugawa, Gota; Ohara, Taku

2015-10-15

The self-diffusion coefficient and molecular-scale structure of several binary n-alkane liquid mixtures in the liquid-vapor interface regions have been examined using molecular dynamics simulations. It was observed that in hexane-tetracosane mixture hexane molecules are accumulated in the liquid-vapor interface region and the accumulation intensity decreases with increase in a molar fraction of hexane in the examined range. Molecular alignment and configuration in the interface region of the liquid mixture change with a molar fraction of hexane. The self-diffusion coefficient in the direction parallel to the interface of both tetracosane and hexane in their binary mixture increases in the interface region. It was found that the self-diffusion coefficient of both tetracosane and hexane in their binary mixture is considerably higher in the vapor side of the interface region as the molar fraction of hexane goes lower, which is mostly due to the increase in local free volume caused by the local structure of the liquid in the interface region.

Thermal Integration of a Liquid Acquisition Device into a Cryogenic Feed System

NASA Technical Reports Server (NTRS)

Hastings, L. J.; Bolshinskiy, L. G.; Schunk, R. G.; Martin, A. K.; Eskridge, R. H.; Frenkel, A.; Grayson, G.; Pendleton, M. L.

2011-01-01

Primary objectives of this effort were to define the following: (1) Approaches for quantification of the accumulation of thermal energy within a capillary screen liquid acquisition device (LAD) for a lunar lander upper stage during periods of up to 210 days on the lunar surface, (2) techniques for mitigating heat entrapment, and (3) perform initial testing, data evaluation. The technical effort was divided into the following categories: (1) Detailed thermal modeling of the LAD/feed system interactions using both COMSOL computational fluid device and standard codes, (2) FLOW-3D modeling of bulk liquid to provide interfacing conditions for the LAD thermal modeling, (3) condensation conditioning of capillary screens to stabilize surface tension retention capability, and (4) subscale testing of an integrated LAD/feed system. Substantial progress was achieved in the following technical areas: (1) Thermal modeling and experimental approaches for evaluating integrated cryogen LAD/feed systems, at both the system and component levels, (2) reduced gravity pressure control analyses, (3) analytical modeling and testing for capillary screen conditioning using condensation and wicking, and (4) development of rapid turnaround testing techniques for evaluating LAD/feed system thermal and fluid integration. A comprehensive effort, participants included a diverse cross section of representatives from academia, contractors, and multiple Marshall Space Flight Center organizations.

Thermodynamic Investigation of the Effect of Interface Curvature on the Solid-Liquid Equilibrium and Eutectic Point of Binary Mixtures.

PubMed

Liu, Fanghui; Zargarzadeh, Leila; Chung, Hyun-Joong; Elliott, Janet A W

2017-10-12

Thermodynamic phase behavior is affected by curved interfaces in micro- and nanoscale systems. For example, capillary freezing point depression is associated with the pressure difference between the solid and liquid phases caused by interface curvature. In this study, the thermal, mechanical, and chemical equilibrium conditions are derived for binary solid-liquid equilibrium with a curved solid-liquid interface due to confinement in a capillary. This derivation shows the equivalence of the most general forms of the Gibbs-Thomson and Ostwald-Freundlich equations. As an example, the effect of curvature on solid-liquid equilibrium is explained quantitatively for the water/glycerol system. Considering the effect of a curved solid-liquid interface, a complete solid-liquid phase diagram is developed over a range of concentrations for the water/glycerol system (including the freezing of pure water or precipitation of pure glycerol depending on the concentration of the solution). This phase diagram is compared with the traditional phase diagram in which the assumption of a flat solid-liquid interface is made. We show the extent to which nanoscale interface curvature can affect the composition-dependent freezing and precipitating processes, as well as the change in the eutectic point temperature and concentration with interface curvature. Understanding the effect of curvature on solid-liquid equilibrium in nanoscale capillaries has applications in the food industry, soil science, cryobiology, nanoporous materials, and various nanoscience fields.

Systems and methods for monitoring a solid-liquid interface

DOEpatents

Stoddard, Nathan G; Lewis, Monte A.; Clark, Roger F

2013-06-11

Systems and methods are provided for monitoring a solid-liquid interface during a casting process. The systems and methods enable determination of the location of a solid-liquid interface during the casting process.

Cyclic Polarization Behavior of ASTM A537-Cl.1 Steel in the Vapor Space Above Simulated Waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiersma, B

2004-11-01

An assessment of the potential degradation mechanisms of Types I and II High-Level Waste (HLW) Tanks determined that pitting corrosion and stress corrosion cracking were the two most significant degradation mechanisms. Specifically, nitrate induced stress corrosion cracking was determined to be the principal degradation mechanism for the primary tank steel of non-stress relieved tanks. Controls on the solution chemistry have been in place to preclude the initiation and propagation of degradation in the tanks. However, recent experience has shown that steel not in contact with the bulk waste solution or slurry, but exposed to the ''vapor space'' above the bulkmore » waste, may be vulnerable to the initiation and propagation of degradation, including pitting and stress corrosion cracking. A program to resolve the issues associated with potential vapor space corrosion is in place. The objective of the program is to develop understanding of vapor space (VSC) and liquid/air interface (LAIC) corrosion to ensure a defensible technical basis to provide accurate corrosion evaluations with regard to vapor space and liquid/air interface corrosion (similar to current evaluations). There are several needs for a technically defensible basis with sufficient understanding to perform these evaluations. These include understanding of the (1) surface chemistry evolution, (2) corrosion response through coupon testing, and (3) mechanistic understanding through electrochemical studies. Experimentation performed in FY02 determined the potential for vapor space and liquid/air interface corrosion of ASTM A285-70 and ASTM A537-Cl.1 steels. The material surface characteristics, i.e. mill-scale, polished, were found to play a key role in the pitting response. The experimentation indicated that the potential for limited vapor space and liquid/air interface pitting exists at 1.5M nitrate solution when using chemistry controls designed to prevent stress corrosion cracking. Experimentation performed in FY03 quantified pitting rates as a function of material surface characteristics, including mill-scale and defects within the mill-scale. Testing was performed on ASTM A537-Cl.1 (normalized) steel, the material of construction of the Type III HLW tanks. The pitting rates were approximately 3 mpy for exposure above inhibited solutions, as calculated from the limited exposure times. This translates to a penetration time of 166 years for a 0.5-in tank wall provided that the pitting rate remains constant and the bulk solution chemistry is maintained within the L3 limit. The FY04 testing consisted of electrochemical testing to potentially lend insight into the surface chemistry and further understand the corrosion mechanism in the vapor space. Electrochemical testing lends insight into the corrosion processes through the determination of current potential relationships. The results of the electrochemical testing performed during FY04 are presented here.« less

Self-pressurization of a spherical liquid hydrogen storage tank in a microgravity environment

NASA Technical Reports Server (NTRS)

Lin, C. S.; Hasan, M. M.

1992-01-01

Thermal stratification and self-pressurization of partially filled liquid hydrogen (LH2) storage tanks under microgravity condition is studied theoretically. A spherical tank is subjected to a uniform and constant wall heat flux. It is assumed that a vapor bubble is located in the tank center such that the liquid-vapor interface and tank wall form two concentric spheres. This vapor bubble represents an idealized configuration of a wetting fluid in microgravity conditions. Dimensionless mass and energy conservation equations for both vapor and liquid regions are numerically solved. Coordinate transformation is used to capture the interface location which changes due to liquid thermal expansion, vapor compression, and mass transfer at liquid-vapor interface. The effects of tank size, liquid fill level, and wall heat flux on the pressure rise and thermal stratification are studied. Liquid thermal expansion tends to cause vapor condensation and wall heat flux tends to cause liquid evaporation at the interface. The combined effects determine the direction of mass transfer at the interface. Liquid superheat increases with increasing wall heat flux and liquid fill level and approaches an asymptotic value.

Controlled microfluidic interfaces for microsensors

NASA Astrophysics Data System (ADS)

Jiang, H.

2009-02-01

Lab on a chip has found many applications in biological and chemical analysis, including pathogen detections. Because these labs on chips involve handling of fluids at the microscale, surface tension profoundly affects the behavior and performance of these systems. Through careful engineering, controlled liquid-liquid or liquid-gas interfaces at the microscale can be formed and used in many interesting applications. In this talk, I will present our work on applying such interfaces to microsensing. These interfaces are created at hydrophobic-hydrophilic boundaries formed within microfluidic channels and pinned by surface tension. We have designed and fabricated a few microsensing techniques including chemical and biological sensing using dissolvable micromembranes in microchannels, chemical and biological sensing at liquid crystals interfacing either air or aqueous solutions, and collection of gaseous samples and aerosols through air-liquid microfludic interfaces. I will next introduce on-chip microlenses and microlens arrays for optical detection, including smart and adaptive liquid microlenses actuated by stimuli-responsive hydrogels, and liquid microlenses in situ formed within microfluidic channels via pneumatic control of droplets.

Determining solid-fluid interface temperature distribution during phase change of cryogenic propellants using transient thermal modeling

NASA Astrophysics Data System (ADS)

Bellur, K.; Médici, E. F.; Hermanson, J. C.; Choi, C. K.; Allen, J. S.

2018-04-01

Control of boil-off of cryogenic propellants is a continuing technical challenge for long duration space missions. Predicting phase change rates of cryogenic liquids requires an accurate estimation of solid-fluid interface temperature distributions in regions where a contact line or a thin liquid film exists. This paper described a methodology to predict inner wall temperature gradients with and without evaporation using discrete temperature measurements on the outer wall of a container. Phase change experiments with liquid hydrogen and methane in cylindrical test cells of various materials and sizes were conducted at the Neutron Imaging Facility at the National Institute of Standards and Technology. Two types of tests were conducted. The first type of testing involved thermal cycling of an evacuated cell (dry) and the second involved controlled phase change with cryogenic liquids (wet). During both types of tests, temperatures were measured using Si-diode sensors mounted on the exterior surface of the test cells. Heat is transferred to the test cell by conduction through a helium exchange gas and through the cryostat sample holder. Thermal conduction through the sample holder is shown to be the dominant mode with the rate of heat transfer limited by six independent contact resistances. An iterative methodology is employed to determine contact resistances between the various components of the cryostat stick insert, test cell and lid using the dry test data. After the contact resistances are established, inner wall temperature distributions during wet tests are calculated.

Liquid phase stabilization versus bubble formation at a nanoscale curved interface

NASA Astrophysics Data System (ADS)

Schiffbauer, Jarrod; Luo, Tengfei

2018-03-01

We investigate the nature of vapor bubble formation near a nanoscale-curved convex liquid-solid interface using two models: an equilibrium Gibbs model for homogenous nucleation, and a nonequilibrium dynamic van der Waals-diffuse-interface model for phase change in an initially cool liquid. Vapor bubble formation is shown to occur for sufficiently large radius of curvature and is suppressed for smaller radii. Solid-fluid interactions are accounted for and it is shown that liquid-vapor interfacial energy, and hence Laplace pressure, has limited influence over bubble formation. The dominant factor is the energetic cost of creating the solid-vapor interface from the existing solid-liquid interface, as demonstrated via both equilibrium and nonequilibrium arguments.

Gas-liquid interface of room-temperature ionic liquids.

PubMed

Santos, Cherry S; Baldelli, Steven

2010-06-01

The organization of ions at the interface of ionic liquids and the vacuum is an ideal system to test new ideas and concepts on the interfacial chemistry of electrolyte systems in the limit of no solvent medium. Whilst electrolyte systems have numerous theoretical and experimental methods used to investigate their properties, the ionic liquids are relatively new and our understanding of the interfacial properties is just beginning to be explored. In this critical review, the gas-liquid interface is reviewed, as this interface does not depend on the preparation of another medium and thus produces a natural interface. The interface has been investigated by sum frequency generation vibrational spectroscopy and ultra-high vacuum techniques. The results provide a detailed molecular-level view of the surface composition and structure. These have been complemented by theoretical studies. The combinations of treatments on this interface are starting to provide a somewhat convergent description of how the ions are organized at this neat interface (108 references).

Asymmetric reduction of benzil to (S)-benzoin with Penicillium claviforme IAM 7294 in a liquid-liquid interface bioreactor (L-L IBR).

PubMed

Oda, Shinobu; Isshiki, Kunio

2008-05-01

The asymmetric reduction of benzyl to (S)-benzoin with Penicillium claviforme IAM 7294 was applied to a liquid-liquid interface bioreactor (L-L IBR) using a unique polymeric material, ballooned microsphere (MS). The L-L IBR showed superior performance, as compared with suspension, organic-aqueous two-liquid-phase, and solid-liquid interface bioreactor (S-L IBR) systems, affording 14.4 g/l-organic phase of (S)-benzoin (99.0% ee).

Investigation of Air-Liquid Interface Rings in Buffer Preparation Vessels: the Role of Slip Agents.

PubMed

Shi, Ting; Ding, Wei; Kessler, Donald W; De Mas, Nuria; Weaver, Douglas G; Pathirana, Charles; Martin, Russell D; Mackin, Nancy A; Casati, Michael; Miller, Scott A; Pla, Itzcoatl A

2016-01-01

Air-liquid interface rings were observed on the side walls of stainless steel buffer vessels after certain downstream buffer preparations. Those rings were resistant to regular cleaning-in-place procedures but could be removed by manual means. To investigate the root cause of this issue, multiple analytical techniques, including liquid chromatography with tandem mass spectrometry detection (LC-MS/MS), high-resolution accurate mass liquid chromatography with mass spectrometry, nuclear magnetic resonance, Fourier transform infrared spectroscopy, and scanning electron microscopy with energy-dispersive X-ray spectroscopy have been employed to characterize the chemical composition of air-liquid interface rings. The main component of air-liquid interface rings was determined to be slip agents, and the origin of the slip agents can be traced back to their presence on raw material packaging liners. Slip agents are commonly used in plastic industry as additives to reduce the coefficient of friction during the manufacturing process of thin films. To mitigate this air-liquid interface ring issue, an alternate liner with low slip agent was identified and implemented with minimal additional cost. We have also proactively tested the packaging liners of other raw materials currently used in our downstream buffer preparation to ensure slip agent levels are appropriate. Air-liquid interface rings were observed on the side walls of stainless steel buffer vessels after certain downstream buffer preparations. To investigate the root cause of this issue, multiple analytical techniques have been employed to characterize the chemical composition of air-liquid interface rings. The main components of air-liquid interface rings were determined to be slip agents, which are common additives used in the manufacturing process of thin films. The origin of the slip agents can be traced back to their presence on certain raw material packaging liners. To mitigate this air-liquid interface ring issue, an alternate liner with low slip agent was identified and implemented. © PDA, Inc. 2016.

Project Interface Requirements Process Including Shuttle Lessons Learned

NASA Technical Reports Server (NTRS)

Bauch, Garland T.

2010-01-01

Most failures occur at interfaces between organizations and hardware. Processing interface requirements at the start of a project life cycle will reduce the likelihood of costly interface changes/failures later. This can be done by adding Interface Control Documents (ICDs) to the Project top level drawing tree, providing technical direction to the Projects for interface requirements, and by funding the interface requirements function directly from the Project Manager's office. The interface requirements function within the Project Systems Engineering and Integration (SE&I) Office would work in-line with the project element design engineers early in the life cycle to enhance communications and negotiate technical issues between the elements. This function would work as the technical arm of the Project Manager to help ensure that the Project cost, schedule, and risk objectives can be met during the Life Cycle. Some ICD Lessons Learned during the Space Shuttle Program (SSP) Life Cycle will include the use of hardware interface photos in the ICD, progressive life cycle design certification by analysis, test, & operations experience, assigning interface design engineers to Element Interface (EI) and Project technical panels, and linking interface design drawings with project build drawings

Pressurization of a Flightweight, Liquid Hydrogen Tank: Evaporation & Condensation at a Liquid/Vapor Interface

NASA Technical Reports Server (NTRS)

Stewart, Mark E. M.

2017-01-01

This paper presents an analysis and simulation of evaporation and condensation at a motionless liquid/vapor interface. A 1-D model equation, emphasizing heat and mass transfer at the interface, is solved in two ways, and incorporated into a subgrid interface model within a CFD simulation. Simulation predictions are compared with experimental data from the CPST Engineering Design Unit tank, a cryogenic fluid management test tank in 1-g. The numerical challenge here is the physics of the liquid/vapor interface; pressurizing the ullage heats it by several degrees, and sets up an interfacial temperature gradient that transfers heat to the liquid phase-the rate limiting step of condensation is heat conducted through the liquid and vapor. This physics occurs in thin thermal layers O(1 mm) on either side of the interface which is resolved by the subgrid interface model. An accommodation coefficient of 1.0 is used in the simulations which is consistent with theory and measurements. This model is predictive of evaporation/condensation rates, that is, there is no parameter tuning.

Indirect measurement of the solid/liquid interface using the minimization technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choi, H.; Chun, M.

1985-11-01

The phenomenon of solidification of a flowing fluid in a vertical tube is closely related to the relocation dynamics of molten nuclear fuels in hypothetical core-disruptive accidents of a liquid-metal fast breeder reactor. The knowledge of the transient shape and the position of the liquid/solid interface is of practical importance in analysis of phase change processes. Sparrow and Broadbent directly measured the solid liquid interface via experiments, whereas Viskanta observed the solid/liquid interface motion via a photographic method. In this paper, a new method to predict the transient position of the solid/liquid interface is developed. This method is based onmore » the minimization technique. To use this method one needs the temperature of the wall on which the phase change is to take place. The new technique is useful, in particular, for the case of inward solidification of a flowing fluid in a tube where direct measurement of the solid/liquid interface is not possible, whereas the tube wall temperature measurement is relatively easy.« less

Probing Electrochemical Reactions at a Plasma-Liquid Interface

DTIC Science & Technology

2015-03-16

at a Plasma- Liquid Interface,” AVS International Symposium and Exhibition, Baltimore, MD , 2014. (presented by P. Rumbach) (c) Presentations Number of... liquid interfacial environment produces different solvated electron behavior than other approaches to generating solvated electrons (e.g., pulse...Mar-2015 Approved for Public Release; Distribution Unlimited Final Report: STIR: Probing Electrochemical Reactions at a Plasma- Liquid Interface (7.2

Bio-inspired Edible Superhydrophobic Interface for Reducing Residual Liquid Food.

PubMed

Li, Yao; Bi, Jingran; Wang, Siqi; Zhang, Tan; Xu, Xiaomeng; Wang, Haitao; Cheng, Shasha; Zhu, Bei-Wei; Tan, Mingqian

2018-03-07

Significant wastage of residual liquid food, such as milk, yogurt, and honey, in food containers has attracted great attention. In this work, a bio-inspired edible superhydrophobic interface was fabricated using U.S. Food and Drug Administration-approved and edible honeycomb wax, arabic gum, and gelatin by a simple and low-cost method. The bio-inspired edible superhydrophobic interface showed multiscale structures, which were similar to that of a lotus leaf surface. This bio-inspired edible superhydrophobic interface displayed high contact angles for a variety of liquid foods, and the residue of liquid foods could be effectively reduced using the bio-inspired interface. To improve the adhesive force of the superhydrophobic interface, a flexible edible elastic film was fabricated between the interface and substrate material. After repeated folding and flushing for a long time, the interface still maintained excellent superhydrophobic property. The bio-inspired edible superhydrophobic interface showed good biocompatibility, which may have potential applications as a functional packaging interface material.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Chun-Lan; Yuan, Hongtao; Li, Yanbin

Electric-double-layer (EDL) gating with liquid electrolyte has been a powerful tool widely used to explore emerging interfacial electronic phenomena. Due to the large EDL capacitance, a high carrier density up to 10 14 cm –2 can be induced, directly leading to the realization of field-induced insulator to metal (or superconductor) transition. However, the liquid nature of the electrolyte has created technical issues including possible side electrochemical reactions or intercalation, and the potential for huge strain at the interface during cooling. In addition, the liquid coverage of active devices also makes many surface characterizations and in situ measurements challenging. Here, wemore » demonstrate an all solid-state EDL device based on a solid superionic conductor LaF 3, which can be used as both a substrate and a fluorine ionic gate dielectric to achieve a wide tunability of carrier density without the issues of strain or electrochemical reactions and can expose the active device surface for external access. Based on LaF 3 EDL transistors (EDLTs), we observe the metal–insulator transition in MoS 2. Interestingly, the well-defined crystal lattice provides a more uniform potential distribution in the substrate, resulting in less interface electron scattering and therefore a higher mobility in MoS 2 transistors. Finally, this result shows the powerful gating capability of LaF 3 solid electrolyte for new possibilities of novel interfacial electronic phenomena.« less

Exposure of Mammalian Cells to Air-Pollutant Mixtures at the Air-Liquid Interface

EPA Science Inventory

It has been widely accepted that exposure of mammalian cells to air-pollutant mixtures at the air-liquid interface is a more realistic approach than exposing cell under submerged conditions. The VITROCELL systems, are commercially available systems for air-liquid interface expo...

Human Apolipoprotein A1 at Solid/Liquid and Liquid/Gas Interfaces.

PubMed

Dogan, Susanne; Paulus, Michael; Forov, Yury; Weis, Christopher; Kampmann, Matthias; Cewe, Christopher; Kiesel, Irena; Degen, Patrick; Salmen, Paul; Rehage, Heinz; Tolan, Metin

2018-04-12

An X-ray reflectivity study on the adsorption behavior of human apolipoprotein A1 (apoA1) at hydrophilic and hydrophobic interfaces is presented. It is shown that the protein interacts via electrostatic and hydrophobic interactions with the interfaces, resulting in the absorption of the protein. pH dependent measurements at the solid/liquid interface between silicon dioxide and aqueous protein solution show that in a small pH range between pH 4 and 6, adsorption is increased due to electrostatic attraction. Here, the native shape of the protein seems to be conserved. In contrast, the adsorption at the liquid/gas interface is mainly driven by hydrophobic effects, presumably by extending the hydrophobic regions of the amphipathic helices, and results in a conformational change of the protein during adsorption. However, the addition of differently charged membrane-forming lipids at the liquid/gas interface illustrates the ability of apoA1 to include lipids, resulting in a depletion of the lipids from the interface.

Electrowetting-actuated zoom lens with spherical-interface liquid lenses.

PubMed

Peng, Runling; Chen, Jiabi; Zhuang, Songlin

2008-11-01

The interface shape of two immiscible liquids in a conical chamber is discussed. The analytical solution of the differential equation describing the interface shape shows that the interface shape is completely spherical when the density difference of two liquids is zero. On the basis of the spherical-interface shape and an energy-minimization method, explicit calculations and detailed analyses of an extended Young-type equation for the conical double-liquid lens are given. Finally, a novel design of a zoom lens system without motorized movements is proposed. The lens system consists of a fixed lens and two conical double-liquid variable-focus lenses. The structure and principle of the lens system are introduced in this paper. Taking finite objects as example, detailed calculations and simulation examples are presented to predict how two liquid lenses are related to meet the basic requirements of zoom lenses.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olivieri, Giorgia; Brown, Matthew A., E-mail: matthew.brown@mat.ethz.ch; Parry, Krista M.

Over the past decade, energy-dependent ambient pressure X-ray photoelectron spectroscopy (XPS) has emerged as a powerful analytical probe of the ion spatial distributions at the vapor (vacuum)-aqueous electrolyte interface. These experiments are often paired with complementary molecular dynamics (MD) simulations in an attempt to provide a complete description of the liquid interface. There is, however, no systematic protocol that permits a straightforward comparison of the two sets of results. XPS is an integrated technique that averages signals from multiple layers in a solution even at the lowest photoelectron kinetic energies routinely employed, whereas MD simulations provide a microscopic layer-by-layer descriptionmore » of the solution composition near the interface. Here, we use the National Institute of Standards and Technology database for the Simulation of Electron Spectra for Surface Analysis (SESSA) to quantitatively interpret atom-density profiles from MD simulations for XPS signal intensities using sodium and potassium iodide solutions as examples. We show that electron inelastic mean free paths calculated from a semi-empirical formula depend strongly on solution composition, varying by up to 30% between pure water and concentrated NaI. The XPS signal thus arises from different information depths in different solutions for a fixed photoelectron kinetic energy. XPS signal intensities are calculated using SESSA as a function of photoelectron kinetic energy (probe depth) and compared with a widely employed ad hoc method. SESSA simulations illustrate the importance of accounting for elastic-scattering events at low photoelectron kinetic energies (<300 eV) where the ad hoc method systematically underestimates the preferential enhancement of anions over cations. Finally, some technical aspects of applying SESSA to liquid interfaces are discussed.« less

Convection-induced distortion of a solid-liquid interface

NASA Technical Reports Server (NTRS)

Schaefer, R. J.; Coriell, S. R.

1984-01-01

Measurements of convective flow fields and solid-liquid interface shapes during the solidification of a pure and a slightly alloyed transparent material reveal that the convective transport of solute can cause a macroscopic depression to develop in the solid-liquid interface. This effect occurs under conditions close to those which are predicted to produce morphological instability of a planar interface. A cellular or dendritic microstructure later develops within the interface depression. The convection is attributed to the effect of radial temperature gradients in the crystal growth apparatus.

Energy dispersive-EXAFS of Pd nucleation at a liquid/liquid interface

NASA Astrophysics Data System (ADS)

Chang, S.-Y.; Booth, S. G.; Uehara, A.; Mosselmans, J. F. W.; Cibin, G.; Pham, V.-T.; Nataf, L.; Dryfe, R. A. W.; Schroeder, S. L. M.

2016-05-01

Energy dispersive extended X-ray absorption fine structure (EDE) has been applied to Pd nanoparticle nucleation at a liquid/liquid interface under control over the interfacial potential and thereby the driving force for nucleation. Preliminary analysis focusing on Pd K edge-step height determination shows that under supersaturated conditions the concentration of Pd near the interface fluctuate over a period of several hours, likely due to the continuous formation and dissolution of sub-critical nuclei. Open circuit potential measurements conducted ex-situ in a liquid/liquid electrochemical cell support this view, showing that the fluctuations in Pd concentration are also visible as variations in potential across the liquid/liquid interface. By decreasing the interfacial potential through inclusion of a common ion (tetraethylammonium, TEA+) the Pd nanoparticle growth rate could be slowed down, resulting in a smooth nucleation process. Eventually, when the TEA+ ions reached an equilibrium potential, Pd nucleation and particle growth were inhibited.

Finite element analysis of the effect of a non-planar solid-liquid interface on the lateral solute segregation during unidirectional solidification

NASA Technical Reports Server (NTRS)

Carlson, F. M.; Chin, L.-Y.; Fripp, A. L.; Crouch, R. K.

1982-01-01

The effect of solid-liquid interface shape on lateral solute segregation during steady-state unidirectional solidification of a binary mixture is calculated under the assumption of no convection in the liquid. A finite element technique is employed to compute the concentration field in the liquid and the lateral segregation in the solid with a curved boundary between the liquid and solid phases. The computational model is constructed assuming knowledge of the solid-liquid interface shape; no attempt is made to relate this shape to the thermal field. The influence of interface curvature on the lateral compositional variation is investigated over a range of system parameters including diffusivity, growth speed, distribution coefficient, and geometric factors of the system. In the limiting case of a slightly nonplanar interface, numerical results from the finite element technique are in good agreement with the analytical solutions of Coriell and Sekerka obtained by using linear theory. For the general case of highly non-planar interface shapes, the linear theory fails and the concentration field in the liquid as well as the lateral solute segregation in the solid can be calculated by using the finite element method.

Young-Laplace equation for liquid crystal interfaces

NASA Astrophysics Data System (ADS)

Rey, Alejandro D.

2000-12-01

This letter uses the classical theories of liquid crystal physics to derive the Young-Laplace equation of capillary hydrostatics for interfaces between viscous isotropic (I) fluids and nematic liquid crystals (NLC's), and establishes the existence of four energy contributions to pressure jumps across these unusual anisotropic interfaces. It is shown that in addition to the usual curvature contribution, bulk and surface gradient elasticity, elastic stress, and anchoring energy contribute to pressure differentials across the interface. The magnitude of the effect is proportional to the elastic moduli of the NLC, and to the bulk and surface orientation gradients that may be present in the nematic phase. In contrast to the planar interface between isotropic fluids, flat liquid crystal interfaces support pressure jumps if elastic stresses, bulk and surface gradient energy, and/or anchoring energies are finite.

Interaction of a sodium ion with the water liquid-vapor interface

NASA Technical Reports Server (NTRS)

Wilson, M. A.; Pohorille, A.; Pratt, L. R.; MacElroy, R. D. (Principal Investigator)

1989-01-01

Molecular dynamics results are presented for the density profile of a sodium ion near the water liquid-vapor interface at 320 K. These results are compared with the predictions of a simple dielectric model for the interaction of a monovalent ion with this interface. The interfacial region described by the model profile is too narrow and the profile decreases too abruptly near the solution interface. Thus, the simple model does not provide a satisfactory description of the molecular dynamics results for ion positions within two molecular diameters from the solution interface where appreciable ion concentrations are observed. These results suggest that surfaces associated with dielectric models of ionic processes at aqueous solution interfaces should be located at least two molecular diameters inside the liquid phase. A free energy expense of about 2 kcal/mol is required to move the ion within two molecular layers of the free water liquid-vapor interface.

Vapor-Enabled Propulsion for Plasmonic Photothermal Motor at the Liquid/Air Interface.

PubMed

Meng, Fanchen; Hao, Wei; Yu, Shengtao; Feng, Rui; Liu, Yanming; Yu, Fan; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

2017-09-13

This paper explores a new propulsion mechanism that is based on the ejection of hot vapor jet to propel the motor at the liquid/air interface. For conventional photothermal motors, which mostly are driven by Marangoni effect, it is challenging to propel those motors at the surfaces of liquids with low surface tension due to the reduced Marangoni effect. With this new vapor-enabled propulsion mechanism, the motors can move rapidly at the liquid/air interface of liquids with a broad range of surface tensions. A design that can accumulate the hot vapor is further demonstrated to enhance both the propulsion force as well as the applicable range of liquids for such motors. This new propulsion mechanism will help open up new opportunities for the photothermal motors with desired motion controls at a wide range of liquid/air interfaces where hot vapor can be generated.

Microscopic properties of ionic liquid/organic semiconductor interfaces revealed by molecular dynamics simulations.

PubMed

Yokota, Yasuyuki; Miyamoto, Hiroo; Imanishi, Akihito; Takeya, Jun; Inagaki, Kouji; Morikawa, Yoshitada; Fukui, Ken-Ichi

2018-05-09

Electric double-layer transistors based on ionic liquid/organic semiconductor interfaces have been extensively studied during the past decade because of their high carrier densities at low operation voltages. Microscopic structures and the dynamics of ionic liquids likely determine the device performance; however, knowledge of these is limited by a lack of appropriate experimental tools. In this study, we investigated ionic liquid/organic semiconductor interfaces using molecular dynamics to reveal the microscopic properties of ionic liquids. The organic semiconductors include pentacene, rubrene, fullerene, and 7,7,8,8-tetracyanoquinodimethane (TCNQ). While ionic liquids close to the substrate always form the specific layered structures, the surface properties of organic semiconductors drastically alter the ionic dynamics. Ionic liquids at the fullerene interface behave as a two-dimensional ionic crystal because of the energy gain derived from the favorable electrostatic interaction on the corrugated periodic substrate.

Mass Accommodation and Chemical Reaction at Gas-Liquid Interfaces

NASA Astrophysics Data System (ADS)

Kolb, C. E.; Williams, L. R.; Jayne, J. T.; Worsnop, D. R.; Davidovits, P.

2006-12-01

The uptake of trace gases by liquid surfaces is an important process that initiates the heterogeneous chemistry of liquid aerosol particles and cloud droplets. We have recently reviewed the available experimental data for liquid aqueous and aqueous/organic surfaces (1). The review highlights some inconsistencies among experimental results and between experimental results and molecular dynamics simulations. Some of these inconsistencies will be evaluated and discussed in terms of the physics of liquid interfaces, the limitations of various experimental techniques and the disparate scales of laboratory experiments and current molecular simulations (1, 2). 1. Davidovits, P., Kolb, C. E., Williams, L. R., Jayne, J. T., Worsnop, D. R., 2006, Mass Accommodation and Chemical Reactions at Gas Liquid Interfaces, Chem. Rev. 106, 1323-1354. 2. Garrett, B. C., Schenter, G. K., Morita, A., 2006, Molecular Simulations of Molecules across the Liquid/Vapor Interface of Water, Chem. Rev. 106, 1355-1374.

Water at silica/liquid water interfaces investigated by DFT-MD simulations

NASA Astrophysics Data System (ADS)

Gaigeot, Marie-Pierre

This talk is dedicated to probing the microscopic structural organization of water at silica/liquid water interfaces including electrolytes by first principles DFT-based molecular dynamics simulations (DFT-MD). We will present our very recent DFT-MD simulations of electrolytic (KCl, NaCl, NaI) silica/liquid water interfaces in order to unravel the intertwined structural properties of water and electrolytes at the crystalline quartz/liquid water and amorphous silica/liquid water interfaces. DFT-MD simulations provide direct knowledge of the structural organization of water and the H-Bond network formed between the water molecules within the different water layers above the silica surface. One can furthermore extract vibrational signatures of the water molecules within the interfacial layers from the DFT-MD simulations, especially non-linear SFG (Sum Frequency generation) signatures that are active at solid/liquid interfaces. The strength of the simulated spectra is that a detailed analysis of the signatures in terms of the water/water H-Bond networks formed within the interfacial water layers and in terms of the water/silica or water/electrolytes H-Bond networks can be given. Comparisons of SFG spectra between quartz/water/electrolytes and amorphous silica/water/electrolytes interfaces allow us to definitely conclude on how the structural arrangements of liquid water at these electrolytic interfaces modulate the final spectroscopic signatures. Invited speaker.

A quantitative study of factors influencing lamellar eutectic morphology during solidification

NASA Technical Reports Server (NTRS)

Kaukler, W. F. S.

1981-01-01

The factors that influence the shape of the solid-liquid interface of a lamellar binary eutectic alloy are evaluated. Alloys of carbon tetrabromide and hexachloroethane which serve as a transparent analogue of lamellar metallic eutectics are used. The observed interface shapes are analyzed by computer-aided methods. The solid-liquid interfacial free energies of each of the individual phases comprising the eutectic system are measured as a function of composition using a 'grain boundary groove' technique. The solid-liquid interfacial free energy of the two phases are evaluated directly from the eutectic interface. The phase diagram for the system, the heat of fusion as a function of composition, and the density as a function of composition are measured. The shape of the eutectic interface is controlled mainly by the solid-liquid and solid-solid interfacial free energy relationships at the interface and by the temperature gradient present, rather than by interlamellar diffusion in the liquid at the interface, over the range of growth rates studied.

Dramatically different kinetics and mechanism at solid/liquid and solid/gas interfaces for catalytic isopropanol oxidation over size-controlled platinum nanoparticles.

PubMed

Wang, Hailiang; Sapi, Andras; Thompson, Christopher M; Liu, Fudong; Zherebetskyy, Danylo; Krier, James M; Carl, Lindsay M; Cai, Xiaojun; Wang, Lin-Wang; Somorjai, Gabor A

2014-07-23

We synthesize platinum nanoparticles with controlled average sizes of 2, 4, 6, and 8 nm and use them as model catalysts to study isopropanol oxidation to acetone in both the liquid and gas phases at 60 °C. The reaction at the solid/liquid interface is 2 orders of magnitude slower than that at the solid/gas interface, while catalytic activity increases with the size of platinum nanoparticles for both the liquid-phase and gas-phase reactions. The activation energy of the gas-phase reaction decreases with the platinum nanoparticle size and is in general much higher than that of the liquid-phase reaction which is largely insensitive to the size of catalyst nanoparticles. Water substantially promotes isopropanol oxidation in the liquid phase. However, it inhibits the reaction in the gas phase. The kinetic results suggest different mechanisms between the liquid-phase and gas-phase reactions, correlating well with different orientations of IPA species at the solid/liquid interface vs the solid/gas interface as probed by sum frequency generation vibrational spectroscopy under reaction conditions and simulated by computational calculations.

Organotypic culture of human amnion cells in air-liquid interface as a potential substitute for skin regeneration.

PubMed

Fatimah, Simat Siti; Chua, Kienhui; Tan, Geok Chin; Azmi, Tengku Ibrahim; Tan, Ay Eeng; Abdul Rahman, Hayati

2013-08-01

The aim of the present study was to evaluate the effects of air-liquid interface on the differentiation potential of human amnion epithelial cells (HAECs) to skin-like substitute in organotypic culture. HAECs at passage 1-2 were seeded onto a fibrin layer populated with human amnion mesenchymal cells to form the organotypic cultures. The organotypic HAECs were then cultured for 7, 14 and 21 d in two types of culture system: the submerged culture and the air-liquid interface culture. Cell morphogenesis was examined under the light and electron microscopes (transmission and scanning) and analyzed by immunohistochemistry. Organotypic HAECs formed a single layer epithelium after 3 wk in submerged as well as air-liquid interface cultures. Ultrastructurally, desmosomes were observed in organotypic HAECs cultured in the air-liquid interface but not in the submerged culture. The presence of desmosomes marked the onset of early epidermal differentiation. Organotypic HAECs were positive against anti-CK18 and anti-CK14 in both the submerged and the air-liquid interface cultures. The co-expression of CK14 and CK18 suggested that differentiation of HAECs into skin may follow the process of embryonic skin development. However, weak expression of CK14 was observed after 2 and 3 wk of culture in air-liquid interface. CK10, involucrin, type IV collagen and laminin-5 expression was absent in organotypic HAECs. This observation reflects the initial process of embryonic epidermal differentiation and stratification. Results from the present study suggest that the air-liquid interface could stimulate early differentiation of organotypic HAECs to epidermal cells, with a potential use for skin regeneration. Copyright © 2013 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

A search for the prewetting line. [in binary liquid system at vapor-liquid interface

NASA Technical Reports Server (NTRS)

Schmidt, J. W.; Moldover, M. R.

1986-01-01

This paper describes efforts to locate the prewetting line in a binary liquid system (isopropanol-perfluoromethylcyclohexane) at the vapor-liquid interface. Tight upper bounds were placed on the temperature separation (0.2 K) between the prewetting line and the line of bulk liquid phase separation. The prewetting line in systems at equilibrium was not detected. Experimental signatures indicative of the prewetting line occurred only in nonequilibrium situations. Several theories predict that the adsorption of one of the components (the fluorocarbon, in this case) at the liquid-vapor interface should increase abruptly, at a temperature sightly above the temperature at which the mixture separates into two liquid phases. A regular solution calculation indicates that this prewetting line should have been easily detectable with the instruments used in this experiment. Significant features of the experiment are: (1) low-gradient thermostatting, (2) in situ stirring, (3) precision ellipsometry from the vapor-liquid interface, (4) high resolution differential index of refraction measurements using a novel cell design, and (5) computer control.

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

PubMed

Geysermans, P; Elyeznasni, N; Russier, V

2005-11-22

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

Study of silicon crystal surface formation based on molecular dynamics simulation results

NASA Astrophysics Data System (ADS)

Barinovs, G.; Sabanskis, A.; Muiznieks, A.

2014-04-01

The equilibrium shape of <110>-oriented single crystal silicon nanowire, 8 nm in cross-section, was found from molecular dynamics simulations using LAMMPS molecular dynamics package. The calculated shape agrees well to the shape predicted from experimental observations of nanocavities in silicon crystals. By parametrization of the shape and scaling to a known value of {111} surface energy, Wulff form for solid-vapor interface was obtained. The Wulff form for solid-liquid interface was constructed using the same model of the shape as for the solid-vapor interface. The parameters describing solid-liquid interface shape were found using values of surface energies in low-index directions known from published molecular dynamics simulations. Using an experimental value of the liquid-vapor interface energy for silicon and graphical solution of Herring's equation, we constructed angular diagram showing relative equilibrium orientation of solid-liquid, liquid-vapor and solid-vapor interfaces at the triple phase line. The diagram gives quantitative predictions about growth angles for different growth directions and formation of facets on the solid-liquid and solid-vapor interfaces. The diagram can be used to describe growth ridges appearing on the crystal surface grown from a melt. Qualitative comparison to the ridges of a Float zone silicon crystal cone is given.

Fabrication of Supramolecular Chirality from Achiral Molecules at the Liquid/Liquid Interface Studied by Second Harmonic Generation.

PubMed

Lin, Lu; Zhang, Zhen; Guo, Yuan; Liu, Minghua

2018-01-09

We present the investigation into the supramolecular chirality of 5-octadecyloxy-2-(2-pyridylazo)phenol (PARC18) at water/1,2-dichloroethane interface by second harmonic generation (SHG). We observe that PARC18 molecules form supramolecular chirality through self-assembly at the liquid/liquid interface although they are achiral molecules. The bulk concentration of PARC18 in the organic phase has profound effects on the supramolecular chirality. By increasing bulk concentration, the enantiomeric excess at the interface first grows and then decreases until it eventually vanishes. Further analysis reveals that the enantiomeric excess is determined by the twist angle of PARC18 molecules at the interface rather than their orientational angle. At lower and higher bulk concentrations, the average twist angle of PARC18 molecules approaches zero, and the assemblies are achiral; whereas at medium bulk concentrations, the average twist angle is nonzero, so that the assemblies show supramolecular chirality. We also estimate the coverage of PARC18 molecules at the interface versus the bulk concentration and fit it to Langmuir adsorption model. The result indicates that PARC18 assemblies show strongest supramolecular chirality in a half-full monolayer. These findings highlight the opportunities for precise control of supramolecular chirality at liquid/liquid interfaces by manipulating the bulk concentration.

Site-Specific Preparation of Intact Solid–Liquid Interfaces by Label-Free In Situ Localization and Cryo-Focused Ion Beam Lift-Out

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zachman, Michael J.; Asenath-Smith, Emily; Estroff, Lara A.

Abstract Scanning transmission electron microscopy (STEM) allows atomic scale characterization of solid–solid interfaces, but has seen limited applications to solid–liquid interfaces due to the volatility of liquids in the microscope vacuum. Although cryo-electron microscopy is routinely used to characterize hydrated samples stabilized by rapid freezing, sample thinning is required to access the internal interfaces of thicker specimens. Here, we adapt cryo-focused ion beam (FIB) “lift-out,” a technique recently developed for biological specimens, to prepare intact internal solid–liquid interfaces for high-resolution structural and chemical analysis by cryo-STEM. To guide the milling process we introduce a label-freein situmethod of localizing subsurface structuresmore » in suitable materials by energy dispersive X-ray spectroscopy (EDX). Monte Carlo simulations are performed to evaluate the depth-probing capability of the technique, and show good qualitative agreement with experiment. We also detail procedures to produce homogeneously thin lamellae, which enable nanoscale structural, elemental, and chemical analysis of intact solid–liquid interfaces by analytical cryo-STEM. This work demonstrates the potential of cryo-FIB lift-out and cryo-STEM for understanding physical and chemical processes at solid–liquid interfaces.« less

Deconstructing Temperature Gradients across Fluid Interfaces: The Structural Origin of the Thermal Resistance of Liquid-Vapor Interfaces

NASA Astrophysics Data System (ADS)

Muscatello, Jordan; Chacón, Enrique; Tarazona, Pedro; Bresme, Fernando

2017-07-01

The interfacial thermal resistance determines condensation-evaporation processes and thermal transport across material-fluid interfaces. Despite its importance in transport processes, the interfacial structure responsible for the thermal resistance is still unknown. By combining nonequilibrium molecular dynamics simulations and interfacial analyses that remove the interfacial thermal fluctuations we show that the thermal resistance of liquid-vapor interfaces is connected to a low density fluid layer that is adsorbed at the liquid surface. This thermal resistance layer (TRL) defines the boundary where the thermal transport mechanism changes from that of gases (ballistic) to that characteristic of dense liquids, dominated by frequent particle collisions involving very short mean free paths. We show that the thermal conductance is proportional to the number of atoms adsorbed in the TRL, and hence we explain the structural origin of the thermal resistance in liquid-vapor interfaces.

Viewpoint 9--molecular structure of aqueous interfaces

NASA Technical Reports Server (NTRS)

Pohorille, A.; Wilson, M. A.

1993-01-01

In this review we summarize recent progress in our understanding of the structure of aqueous interfaces emerging from molecular level computer simulations. It is emphasized that the presence of the interface induces specific structural effects which, in turn, influence a wide variety of phenomena occurring near the phase boundaries. At the liquid-vapor interface, the most probable orientations of a water molecule is such that its dipole moment lies parallel to the interface, one O-H bond points toward the vapor and the other O-H bond is directed toward the liquid. The orientational distributions are broad and slightly asymmetric, resulting in an excess dipole moment pointing toward the liquid. These structural preferences persist at interfaces between water and nonpolar liquids, indicating that the interactions between the two liquids in contact are weak. It was found that liquid-liquid interfaces are locally sharp but broadened by capillary waves. One consequence of anisotropic orientations of interfacial water molecules is asymmetric interactions, with respect to the sign of the charge, of ions with the water surface. It was found that even very close to the surface ions retain their hydration shells. New features of aqueous interfaces have been revealed in studies of water-membrane and water-monolayer systems. In particular, water molecules are strongly oriented by the polar head groups of the amphiphilic phase, and they penetrate the hydrophilic head-group region, but not the hydrophobic core. At infinite dilution near interfaces, amphiphilic molecules exhibit behavior different from that in the gas phase or in bulk water. This result sheds new light on the nature of hydrophobic effect in the interfacial regions. The presence of interfaces was also shown to affect both equilibrium and dynamic components of rates of chemical reactions. Applications of continuum models to interfacial problems have been, so far, unsuccessful. This, again, underscores the importance of molecular-level information about interfaces.

Thermal boundary conductance of hydrophilic and hydrophobic ionic liquids

NASA Astrophysics Data System (ADS)

Oyake, Takafumi; Sakata, Masanori; Yada, Susumu; Shiomi, Junichiro

2015-03-01

A solid/liquid interface plays a critical role for understanding mechanisms of biological and physical science. Moreover, carrier density of the surface is dramatically enhanced by electric double layer with ionic liquid, salt in the liquid state. Here, we have measured the thermal boundary conductance (TBC) across an interface of gold thin film and ionic liquid by using time-domain thermoreflectance technique. Following the prior researches, we have identified the TBC of two interfaces. One is gold and hydrophilic ionic liquid, N,N-Diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate (DEME-BF4), which is a hydrophilic ionic liquid, and the other is N,N-Diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) imide (DEME-TFSI), which is a hydrophobic ionic liquid. We found that the TBC between gold and DEME-TFIS (19 MWm-2K-1) is surprisingly lower than the interface between gold and DEME-BF4 (45 MWm-2K-1). With these data, the importance of the wetting angle and ion concentration for the thermal transport at the solid/ionic liquid interface is discussed. Part of this work is financially supported by Japan Society for the Promotion of Science (JSPS) and Japan Science and Technology Agency. The author is financially supported by JSPS Fellowship.

Formation of Singularities at the Interface of Liquid Dielectrics in a Horizontal Electric Field in the Presence of Tangential Velocity Discontinuity

NASA Astrophysics Data System (ADS)

Zubarev, N. M.; Kochurin, E. A.

2018-03-01

Nonlinear dynamics of the interface of dielectric liquids under the conditions of suppression of the Kelvin-Helmholz instability by a tangential electric field has been investigated. Two broad classes of exact analytical solutions to the equations of motion describing the evolution of spatially localized and periodic interface perturbations have been found. Both classes of solutions tend to the formation of strong singularities: interface discontinuities with formally infinite amplitudes. The discontinuity sign is determined by the sign of liquid velocity jump at the interface.

Liquid crystal interfaces: Experiments, simulations and biosensors

NASA Astrophysics Data System (ADS)

Popov, Piotr

Interfacial phenomena are ubiquitous and extremely important in various aspects of biological and industrial processes. For example, many liquid crystal applications start by alignment with a surface. The underlying mechanisms of the molecular organization of liquid crystals at an interface are still under intensive study and continue to be important to the display industry in order to develop better and/or new display technology. My dissertation research has been devoted to studying how complex liquid crystals can be guided to organize at an interface, and to using my findings to develop practical applications. Specifically, I have been working on developing biosensors using liquid-crystal/surfactant/lipid/protein interactions as well as the alignment of low-symmetry liquid crystals for potential new display and optomechanical applications. The biotechnology industry needs better ways of sensing biomaterials and identifying various nanoscale events at biological interfaces and in aqueous solutions. Sensors in which the recognition material is a liquid crystal naturally connects the existing knowledge and experience of the display and biotechnology industries together with surface and soft matter sciences. This dissertation thus mainly focuses on the delicate phenomena that happen at liquid interfaces. In the introduction, I start by defining the interface and discuss its structure and the relevant interfacial forces. I then introduce the general characteristics of biosensors and, in particular, describe the design of biosensors that employ liquid crystal/aqueous solution interfaces. I further describe the basic properties of liquid crystal materials that are relevant for liquid crystal-based biosensing applications. In CHAPTER 2, I describe the simulation methods and experimental techniques used in this dissertation. In CHAPTER 3 and CHAPTER 4, I present my computer simulation work. CHAPTER 3 presents insight of how liquid crystal molecules are aligned by hydrocarbon surfaces at the atomic level. I show that the vertical alignment of a rod-like liquid crystal molecule first requires its insertion into the alignment layer. In CHAPTER 4, I investigate the Brownian behavior of a tracer molecule at an oil/water interface and explain the experimentally-observed anomaly of its increased mobility. Following my molecular dynamics simulation studies of liquid interfaces, I continue my work in CHAPTER 5 with experimental research. I employ the high sensitivity of liquid crystal alignment to the presence of amphiphiles adsorbed to the liquid crystal surface from water for potential biosensor applications. I propose a more accurate method of sensing using circular polarization and spectrophotometry. In CHAPTER 6, I investigate if cholesteric and smectic liquid crystals can potentially offer new modes of biosensing. In CHAPTER 7, I describe preliminary results toward constructing a liquid crystal biosensor platform with capabilities of specific sensitivity using proteins and antibodies. Finally in CHAPTER 8, I summarize the findings of my studies and research and suggest possible future experiments to further advance our knowledge in interfacial science for future applications.

3-D Distribution of Retained Colloids in Unsaturated Porous Media

NASA Astrophysics Data System (ADS)

Morales, V. L.; Perez-Reche, F. J.; Holzner, M.; Kinzelbach, W. K.; Otten, W.

2013-12-01

It is well accepted that colloid transport processes in porous media differ substantially between water saturated and unsaturated conditions. Differences are frequently ascribed to colloid immobilization by association with interfaces with the gas, as well as to restrictions of the liquid medium through which colloids are transported. Such factors depend on interfacial conditions provided by the water saturation of the porous medium. Yet, the current understanding of the importance of colloid retention at gas interfaces is based on observations of single pores or two-dimensional pore network representations, leaving open the question of their statistical significance when all pores in the medium are considered. In order to address this question, column experiments were performed using a model porous medium of glass beads through which colloidal silver particles were transported for conditions of varying water content. X-ray microtomography was subsequently employed as a non-destructive imaging technique to obtain pore-scale information of the entire column regarding: i) the presence and distribution of the four main locations where colloids can become retained (interfaces with the liquid-solid, gas-liquid and gas-solid, and the bulk liquid), ii) deposition profiles of colloids along the column classified by the available retention location, iii) morphological characteristics of the deposited colloidal aggregates, and iv) channel widths of 3-dimensional pore-water network representations. The results presented provide, for the first time, a direct statistical evaluation on the significance of colloid retention by attachment to the liquid-solid, gas-liquid, gas-solid interfaces, and by straining in the bulk liquid. Additionally, an effective-pore structure characteristic is proposed to improve predictions of mass removal by straining under various water saturations. A) Unsaturated conditions. B) Saturated conditions. Left: Tomograph slice illustrating with false coloring Regions Of Interest corresponding to retention locations at the gas-liquid (purple), gas-solid (white) and solid-liquid interface (blue), and the bulk liquid (teal). Right: Deposition profiles of silver colloids (Ag) per retention location (T: total, GLI: gas-liquid interface, GSI: gas-solid interface, SLI: solid-liquid interface, L: bulk liquid) (Top). Depth profiles of the volume occupied by each retention location (Middle). Normalized deposition profiles of silver volume retained by its corresponding retention-location volume (Bottom).

Nano-inspired fluidic interactivity for boiling heat transfer: impact and criteria

PubMed Central

Kim, Beom Seok; Choi, Geehong; Shin, Sangwoo; Gemming, Thomas; Cho, Hyung Hee

2016-01-01

The enhancement of boiling heat transfer, the most powerful energy-transferring technology, will lead to milestones in the development of high-efficiency, next-generation energy systems. Perceiving nano-inspired interface functionalities from their rough morphologies, we demonstrate interface-induced liquid refreshing is essential to improve heat transfer by intrinsically avoiding Leidenfrost phenomenon. High liquid accessibility of hemi-wicking and catalytic nucleation, triggered by the morphological and hydrodynamic peculiarities of nano-inspired interfaces, contribute to the critical heat flux (CHF) and the heat transfer coefficient (HTC). Our experiments show CHF is a function of universal hydrodynamic characteristics involving interfacial liquid accessibility and HTC is improved with a higher probability of smaller nuclei with less superheat. Considering the interface-induced and bulk liquid accessibility at boiling, we discuss functionalizing the interactivity between an interface and a counteracting fluid seeking to create a novel interface, a so-called smart interface, for a breakthrough in boiling and its pragmatic application in energy systems. PMID:27708341

Ambient-Pressure X-ray Photoelectron Spectroscopy to Characterize the Solid/Liquid Interface: Probing the Electrochemical Double Layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Favaro, Marco; Liu, Zhi; Crumlin, Ethan J.

Ambient-pressure X-ray photoelectron spectroscopy (APXPS) has contributed greatly to a wide range of research fields, including environmental science, catalysis, and electrochemistry, to name a few. The use of this technique at synchrotron facilities primarily focused on probing the solid/gas interface; however, it quickly advanced to the probing of liquid/vapor interfaces and solid/liquid interfaces through an X-ray-transparent window. Most recently, combining APXPS with “Tender” X-rays (~2.5 keV to 8 keV) on beamline 9.3.1 at the Advanced Light Source in Lawrence Berkeley National Laboratory (which can generate photoelectrons with much longer inelastic mean free paths) has enabled us to probe the solid/liquidmore » interface without needing a window. This innovation allows us to probe interfacial chemistries of electrochemically controlled solid/liquid interfaces undergoing charge transfer reactions. Lastly, these advancements have transitioned APXPS from a traditional surface science tool to an essential interface science technique.« less

Ambient-Pressure X-ray Photoelectron Spectroscopy to Characterize the Solid/Liquid Interface: Probing the Electrochemical Double Layer

DOE PAGES

Favaro, Marco; Liu, Zhi; Crumlin, Ethan J.

2017-03-31

Ambient-pressure X-ray photoelectron spectroscopy (APXPS) has contributed greatly to a wide range of research fields, including environmental science, catalysis, and electrochemistry, to name a few. The use of this technique at synchrotron facilities primarily focused on probing the solid/gas interface; however, it quickly advanced to the probing of liquid/vapor interfaces and solid/liquid interfaces through an X-ray-transparent window. Most recently, combining APXPS with “Tender” X-rays (~2.5 keV to 8 keV) on beamline 9.3.1 at the Advanced Light Source in Lawrence Berkeley National Laboratory (which can generate photoelectrons with much longer inelastic mean free paths) has enabled us to probe the solid/liquidmore » interface without needing a window. This innovation allows us to probe interfacial chemistries of electrochemically controlled solid/liquid interfaces undergoing charge transfer reactions. Lastly, these advancements have transitioned APXPS from a traditional surface science tool to an essential interface science technique.« less

Quantitative interpretation of molecular dynamics simulations for X-ray photoelectron spectroscopy of aqueous solutions

NASA Astrophysics Data System (ADS)

Olivieri, Giorgia; Parry, Krista M.; Powell, Cedric J.; Tobias, Douglas J.; Brown, Matthew A.

2016-04-01

Over the past decade, energy-dependent ambient pressure X-ray photoelectron spectroscopy (XPS) has emerged as a powerful analytical probe of the ion spatial distributions at the vapor (vacuum)-aqueous electrolyte interface. These experiments are often paired with complementary molecular dynamics (MD) simulations in an attempt to provide a complete description of the liquid interface. There is, however, no systematic protocol that permits a straightforward comparison of the two sets of results. XPS is an integrated technique that averages signals from multiple layers in a solution even at the lowest photoelectron kinetic energies routinely employed, whereas MD simulations provide a microscopic layer-by-layer description of the solution composition near the interface. Here, we use the National Institute of Standards and Technology database for the Simulation of Electron Spectra for Surface Analysis (SESSA) to quantitatively interpret atom-density profiles from MD simulations for XPS signal intensities using sodium and potassium iodide solutions as examples. We show that electron inelastic mean free paths calculated from a semi-empirical formula depend strongly on solution composition, varying by up to 30% between pure water and concentrated NaI. The XPS signal thus arises from different information depths in different solutions for a fixed photoelectron kinetic energy. XPS signal intensities are calculated using SESSA as a function of photoelectron kinetic energy (probe depth) and compared with a widely employed ad hoc method. SESSA simulations illustrate the importance of accounting for elastic-scattering events at low photoelectron kinetic energies (<300 eV) where the ad hoc method systematically underestimates the preferential enhancement of anions over cations. Finally, some technical aspects of applying SESSA to liquid interfaces are discussed.

Gate-Induced Metal–Insulator Transition in MoS 2 by Solid Superionic Conductor LaF 3

DOE PAGES

Wu, Chun-Lan; Yuan, Hongtao; Li, Yanbin; ...

2018-03-23

Electric-double-layer (EDL) gating with liquid electrolyte has been a powerful tool widely used to explore emerging interfacial electronic phenomena. Due to the large EDL capacitance, a high carrier density up to 10 14 cm –2 can be induced, directly leading to the realization of field-induced insulator to metal (or superconductor) transition. However, the liquid nature of the electrolyte has created technical issues including possible side electrochemical reactions or intercalation, and the potential for huge strain at the interface during cooling. In addition, the liquid coverage of active devices also makes many surface characterizations and in situ measurements challenging. Here, wemore » demonstrate an all solid-state EDL device based on a solid superionic conductor LaF 3, which can be used as both a substrate and a fluorine ionic gate dielectric to achieve a wide tunability of carrier density without the issues of strain or electrochemical reactions and can expose the active device surface for external access. Based on LaF 3 EDL transistors (EDLTs), we observe the metal–insulator transition in MoS 2. Interestingly, the well-defined crystal lattice provides a more uniform potential distribution in the substrate, resulting in less interface electron scattering and therefore a higher mobility in MoS 2 transistors. Finally, this result shows the powerful gating capability of LaF 3 solid electrolyte for new possibilities of novel interfacial electronic phenomena.« less

Nonlinear dynamics of confined thin liquid-vapor bilayer systems with phase change

NASA Astrophysics Data System (ADS)

Kanatani, Kentaro; Oron, Alexander

2011-03-01

We numerically investigate the nonlinear evolution of the interface of a thin liquid-vapor bilayer system confined by rigid horizontal walls from both below and above. The lateral variation of the vapor pressure arising from phase change is taken into account in the present analysis. When the liquid (vapor) is heated (cooled) and gravity acts toward the liquid, the deflection of the interface monotonically grows, leading to a rupture of the vapor layer, whereas nonruptured stationary states are found when the liquid (vapor) is cooled (heated) and gravity acts toward the vapor. In the latter case, vapor-flow-driven convective cells are found in the liquid phase in the stationary state. The average vapor pressure and interface temperature deviate from their equilibrium values once the interface departs from the flat equilibrium state. Thermocapillarity does not have a significant effect near the thermodynamic equilibrium, but becomes important if the system significantly deviates from it.

Fluorescent optical liquid level sensor

DOEpatents

Weiss, Jonathan D.

2001-01-01

A liquid level sensor comprising a transparent waveguide containing fluorescent material that is excited by light of a first wavelength and emits at a second, longer wavelength. The upper end of the waveguide is connected to a light source at the first wavelength through a beveled portion of the waveguide such that the input light is totally internally reflected within the waveguide above an air/liquid interface in a tank but is transmitted into the liquid below this interface. Light is emitted from the fluorescent material only in those portions of the waveguide that are above the air/liquid interface, to be collected at the upper end of the waveguide by a detector that is sensitive only to the second wavelength. As the interface moves down in the tank, the signal strength from the detector will increase.

Universal adsorption at the vapor-liquid interface near the consolute point

NASA Technical Reports Server (NTRS)

Schmidt, James W.

1990-01-01

The ellipticity of the vapor-liquid interface above mixtures of methylcyclohexane (C7H14) and perfluoromethylcyclohexane (C7F14) has been measured near the consolute point T(c) = 318.6 K. The data are consistent with a model of the interface that combines a short-ranged density-vs height profile in the vapor phase with a much longer-ranged composition-versus-height profile in the liquid. The value of the free parameter produced by fitting the model to the data is consistent with results from two other simple mixtures and a mixture of a polymer and solvent. This experiment combines precision ellipsometry of the vapor-liquid interface with in situ measurements of refractive indices of the liquid phases, and it precisely locates the consolute point.

Electronic functions of solid-to-liquid interfaces of organic semiconductor crystals and ionic liquid

NASA Astrophysics Data System (ADS)

Takeya, J.

2008-10-01

The environment of surface electrons at 'solid-to-liquid' interfaces is somewhat extreme, subjected to intense local electric fields or harsh chemical pressures that high-density ionic charge or polarization of mobile molecules create. In this proceedings, we argue functions of electronic carriers generated at the surface of organic semiconductor crystals in response to the local electric fields in the very vicinity of the interface to ionic liquid. The ionic liquids (ILs), or room temperature molten salts, are gaining considerable interest in the recent decade at the prospect of nonvolatile 'green solvents', with the development of chemically stable and nontoxic compounds. Moreover, such materials are also applied to electrolytes for lithium ion batteries and electric double-layer (EDL) capacitors. Our present solid-to-liquid interfaces of rubrene single crystals and ionic liquids work as fast-switching organic field-effect transistors (OFETs) with the highest transconductance, i.e. the most efficient response of the output current to the input voltage, among the OFETs ever built.

Thermal Transport at Solid-Liquid Interfaces: High Pressure Facilitates Heat Flow through Nonlocal Liquid Structuring.

PubMed

Han, Haoxue; Mérabia, Samy; Müller-Plathe, Florian

2017-05-04

The integration of three-dimensional microelectronics is hampered by overheating issues inherent to state-of-the-art integrated circuits. Fundamental understanding of heat transfer across soft-solid interfaces is important for developing efficient heat dissipation capabilities. At the microscopic scale, the formation of a dense liquid layer at the solid-liquid interface decreases the interfacial heat resistance. We show through molecular dynamics simulations of n-perfluorohexane on a generic wettable surface that enhancement of the liquid structure beyond a single adsorbed layer drastically enhances interfacial heat conductance. Pressure is used to control the extent of the liquid layer structure. The interfacial thermal conductance increases with pressure values up to 16.2 MPa at room temperature. Furthermore, it is shown that liquid structuring enhances the heat-transfer rate of high-energy lattice waves by broadening the transmission peaks in the heat flux spectrum. Our results show that pressure is an important external parameter that may be used to control interfacial heat conductance at solid-soft interfaces.

Numerical Simulations for Turbulent Drag Reduction Using Liquid Infused Surfaces

NASA Astrophysics Data System (ADS)

Arenas-Navarro, Isnardo

Numerical simulations of the turbulent flow over Super Hydrophobic and Liquid Infused Surfaces have been performed in this work. Three different textured surfaces have been considered: longitudinal square bars, transversal square bars and staggered cubes. The numerical code combines an immersed boundary method to mimic the substrate and a level set method to track the interface. Liquid Infused Surfaces reduce the drag by locking a lubricant within structured roughness to facilitate a slip velocity at the surface interface. The conceptual idea is similar to Super Hydrophobic Surfaces, which rely on a lubricant air layer, whereas liquid-infused surfaces use a preferentially wetting liquid lubricant to create a fluid-fluid interface. This slipping interface has been shown to be an effective method of passively reducing skin friction drag in turbulent flows. Details are given on the effect of the viscosity ratio between the two fluids and the dynamics of the interface on drag reduction. An attempt has been made to reconcile Super-Hydrophobic, Liquid Infused and rough wall under the same framework by correlating the drag to the wall normal velocity fluctuations.

Partial liquid-penetration inside a deep trench by film flowing over it

NASA Astrophysics Data System (ADS)

Nguyen, Phuc-Khanh; Dimakopoulos, Yiannis; Tsamopoulos, John

2014-11-01

Liquid film flow along substrates featuring a deep trench may not wet the trench floor, but create a second gas-liquid interface inside the trench. The liquid penetration inside the trench depends on the location and shape of this inner interface. The penetration increases by decreasing the two three-phase contact lines between the inner interface and the two side-walls or the flow rate and depends on the liquid properties. This partial-penetration is studied by employing the Galerkin / finite element method to solve the two-dimensional steady-state Navier-Stokes equations in a physical domain that is adaptively remeshed. Multiple branches of steady solutions connected via turning points are revealed by pseudo arc-length continuation. Flow hysteresis may occur in a certain range of liquid penetration depth, when the interaction of the two interfaces changes qualitatively. This induces an abrupt jump of penetration distance and deformation amplitude of the outer interface. Work supported by the General Secretariat of Research & Technology of Greece through the program ``Excellence'' (Grant No. 1918) in the framework ``Education and Lifelong Learning'' co-funded by the ESF.

Role of adsorption in liquid lubrication

NASA Technical Reports Server (NTRS)

Groszek, A. J.

1973-01-01

Changes at solid-liquid interfaces caused by adsorption from solution are discussed paying attention to the following aspects: (1) stability of adsorbed films and the structure of metal-additive-film-liquid interface and effect of adsorbate orientation. (2) chemical versus physical adsorption, (3) heat of adsorption, (4) adsorption of additives, (5) activated adsorption, effect of activating adsorbates, (6) displacement phenomena at solid-liquid interfaces, (7) competition of antiwear additives, their solvents, and water, (8) effect of adsorption on the orientation of liquid in the interfacial region, and (9) relation between the chemical nature of solid surfaces and their interaction with liquid lubricants. The relevance of the above adsorption phenomena to lubrication is discussed, referring where possible to specific examples.

Computational Studies of [Bmim][PF6]/n-Alcohol Interfaces with Many-Body Potentials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Tsun-Mei; Dang, Liem X.

2014-09-04

In this paper, we present the results from molecular-dynamics simulations of the equilibrium properties of liquid/liquid interfaces of room temperature ionic liquid [bmim][PF6] and simple alcohols (i.e., methanol, 1-butanol, and 1-hexanol) at room temperature. Polarizable potential models are employed to describe the interactions among species. Results from our simulations show stable interfaces between the ionic liquid and n-alcohols, and we found that the interfacial widths decrease from methanol to 1-butanol systems, and then increase for 1-hexanol interfaces. Angular distribution analysis reveals that the interface induces a strong orientational order of [bmim] and n-alcohol molecules near the interface, with [bmim] extendingmore » its butyl group into the alcohol phase while the alcohol has the OH group pointing into the ion liquid region, which is consistent with the recent sum-frequency-generation experiments. We found the interface to have a significant influence on the dynamics of ionic liquids and n-alcohols. The orientational autocorrelation functions illustrate that [bmim] rotate more freely near the interface than in the bulk, while the rotation of n-alcohol is hindered at the interface. Additionally, the time scale associated with the diffusion along the interfacial direction is found to be faster for [bmim] but slowed down for n-alcohols approaching the interface. We also calculate the dipole moment of n-alcohols as a function of the distance normal to the interface. We found that, even though methanol and 1-butanol have different dipole moments in bulk phase, they reach a similar value at the interface. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. Pacific Northwest National Laboratory is a multiprogram national laboratory operated for the Department of Energy by Battelle. The calculations were carried out using computer resources provided by the Office of Basic Energy Sciences.« less

Ultrasonic transmission at solid-liquid interfaces

NASA Astrophysics Data System (ADS)

Wadley, Haydn N. G.; Queheillalt, Douglas T.; Lu, Yichi

1996-11-01

New non-invasive solid-liquid interface sensing technologies are a key element in the development of improved Bridman growth techniques for synthesizing single crystal semiconductor materials. Laser generated and optically detect ultrasonic techniques have the potential to satisfy this need. Using an anisotropic 3D ray tracing methodology combined with elastic constant data measured near the melting point, ultrasonic propagation in cylindrical single crystal bodies containing either a convex, flat, or concave solid-liquid interface has been simulated. Ray paths, wavefronts and the time-of-flight (TOF) of rays that travel from a source to an arbitrarily positioned receiver have all been calculated. Experimentally measured TOF data have been collected using laser generated, optically detected ultrasound on model systems with independently known interface shapes. Both numerically simulated and experimental data have shown that the solidification region can be easily identified from transmission TOF measurements because the velocity of the liquid is much smaller than that of the solid. Since convex and concave solid-liquid interfaces result in distinctively different TOF data profiles, the interface shape can also be readily determined from the TOF data. When TOF data collected in the diametral plane is used in conjunction with a nonlinear least squares algorithm, the interface geometry has been successfully reconstructed and ultrasonic velocities of both the solid and liquid obtained with reconstruction errors less than 5 percent.

Plasma-based water purification: Challenges and prospects for the future

NASA Astrophysics Data System (ADS)

Foster, John E.

2017-05-01

Freshwater scarcity derived from seasonal weather variations, climate change, and over-development has led to serious consideration for water reuse. Water reuse involves the direct processing of wastewater for either indirect or directly potable water reuse. In either case, advanced water treatment technologies will be required to process the water to the point that it can be reused in a meaningful way. Additionally, there is growing concern regarding micropollutants, such as pharmaceuticals and personal care products, which have been detected in finished drinking water not removed by conventional means. The health impact of these contaminants in low concentration is not well understood. Pending regulatory action, the removal of these contaminants by water treatment plants will also require advanced technology. One new and emerging technology that could potentially address the removal of micropollutants in both finished drinking water as well as wastewater slated for reuse is plasma-based water purification. Plasma in contact with liquid water generates a host of reactive species that attack and ultimately mineralize contaminants in solution. This interaction takes place in the boundary layer or interaction zone centered at the plasma-liquid water interface. An understanding of the physical processes taking place at the interface, though poorly understood, is key to the optimization of plasma-based water purifiers. High electric field conditions, large density gradients, plasma-driven chemistries, and fluid dynamic effects prevail in this multiphase region. The region is also the source function for longer-lived reactive species that ultimately treat the water. Here, we review the need for advanced water treatment methods and in the process, make the case for plasma-based methods. Additionally, we survey the basic methods of interacting plasma with liquid water (including a discussion of breakdown processes in water), the current state of understanding of the physical processes taking place at the plasma-liquid interface, and the role these processes play in water purification. The development of plasma diagnostics usable in this multiphase environment along with modeling efforts aimed at elucidating physical processes taking place at the interface are also detailed. Key experiments that demonstrate the capability of plasma-based water treatment are also reviewed. The technical challenges to the implementation of plasma-based water reactors are also discussed. We conclude with a discussion of prospects for the future of plasma-based water purification.

Viscous flow drag reduction; Symposium, Dallas, Tex., November 7, 8, 1979, Technical Papers

NASA Technical Reports Server (NTRS)

Hough, G. R.

1980-01-01

The symposium focused on laminar boundary layers, boundary layer stability analysis of a natural laminar flow glove on the F-111 TACT aircraft, drag reduction of an oscillating flat plate with an interface film, electromagnetic precipitation and ducting of particles in turbulent boundary layers, large eddy breakup scheme for turbulent viscous drag reduction, blowing and suction, polymer additives, and compliant surfaces. Topics included influence of environment in laminar boundary layer control, generation rate of turbulent patches in the laminar boundary layer of a submersible, drag reduction of small amplitude rigid surface waves, and hydrodynamic drag and surface deformations generated by liquid flows over flexible surfaces.

Developing interface localized liquid dielectrophoresis for optical applications

NASA Astrophysics Data System (ADS)

McHale, Glen; Brown, Carl V.; Newton, Michael I.; Wells, Gary G.; Sampara, Naresh

2012-11-01

Electrowetting charges the solid-liquid interface to change the contact area of a droplet of a conducting liquid. It is a powerful technique used to create variable focus liquid lenses, electronic paper and other devices, but it depends upon ions within the liquid. Liquid dielectrophoresis (L-DEP) is a bulk force acting on the dipoles throughout a dielectric liquid and is not normally considered to be a localized effect acting at the interface between the liquid and a solid or other fluid. In this work, we show theoretically how non-uniform electric fields generated by interdigitated electrodes can effectively convert L-DEP into an interface localized form. We show that for droplets of sufficient thickness, the change in the cosine of the contact angle is proportional to the square of the applied voltage and so obeys a similar equation to that for electrowetting - this we call dielectrowetting. However, a major difference to electrowetting is that the strength of the effect is controlled by the electrode spacing and the liquid permittivity rather than the properties of an insulator in a sandwich structure. Experimentally, we show that that this dielectrowetting equation accurately describes the contact angle of a droplet of oil viewed across parallel interdigitated electrodes. Importantly, the induced spreading can be complete, such that contact angle saturation does not occur. We then show that for thin films, L-DEP can shape the liquid-air interface creating a spatially periodic wrinkle and that such a wrinkle can be used to create a voltage programmable phase diffraction grating.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barbante, Paolo; Frezzotti, Aldo; Gibelli, Livio

The unsteady evaporation of a thin planar liquid film is studied by molecular dynamics simulations of Lennard-Jones fluid. The obtained results are compared with the predictions of a diffuse interface model in which capillary Korteweg contributions are added to hydrodynamic equations, in order to obtain a unified description of the liquid bulk, liquid-vapor interface and vapor region. Particular care has been taken in constructing a diffuse interface model matching the thermodynamic and transport properties of the Lennard-Jones fluid. The comparison of diffuse interface model and molecular dynamics results shows that, although good agreement is obtained in equilibrium conditions, remarkable deviationsmore » of diffuse interface model predictions from the reference molecular dynamics results are observed in the simulation of liquid film evaporation. It is also observed that molecular dynamics results are in good agreement with preliminary results obtained from a composite model which describes the liquid film by a standard hydrodynamic model and the vapor by the Boltzmann equation. The two mathematical model models are connected by kinetic boundary conditions assuming unit evaporation coefficient.« less

The electrode/ionic liquid interface: electric double layer and metal electrodeposition.

PubMed

Su, Yu-Zhuan; Fu, Yong-Chun; Wei, Yi-Min; Yan, Jia-Wei; Mao, Bing-Wei

2010-09-10

The last decade has witnessed remarkable advances in interfacial electrochemistry in room-temperature ionic liquids. Although the wide electrochemical window of ionic liquids is of primary concern in this new type of solvent for electrochemistry, the unusual bulk and interfacial properties brought about by the intrinsic strong interactions in the ionic liquid system also substantially influence the structure and processes at electrode/ionic liquid interfaces. Theoretical modeling and experimental characterizations have been indispensable in reaching a microscopic understanding of electrode/ionic liquid interfaces and in elucidating the physics behind new phenomena in ionic liquids. This Minireview describes the status of some aspects of interfacial electrochemistry in ionic liquids. Emphasis is placed on high-resolution and molecular-level characterization by scanning tunneling microscopy and vibrational spectroscopies of interfacial structures, and the initial stage of metal electrodeposition with application in surface nanostructuring.

Pressurization of a Flightweight, Liquid Hydrogen Tank: Evaporation and Condensation at a Liquid Vapor Interface

NASA Technical Reports Server (NTRS)

Stewart, Mark

2017-01-01

Evaporation and condensation at a liquid-vapor interface is important for long-term, in-space cryogenic propellant storage. Yet the current understanding of inter-facial physics does not consistently predict behavior of evaporation or condensation rates. The proposed paper will present a physical model, based on the 1-D Heat equation and Schrage's equation, which demonstrates thin thermal layers at the fluid vapor interface.

A molecular theory of liquid interfaces.

PubMed

Kovalenko, Andriy; Hirata, Fumio

2005-04-21

We propose a site site generalization of the Lovett-Mow-Buff-Wertheim integro-differential equation for the one-particle density distributions to polyatomic fluids. The method provides microscopic description of liquid interfaces of molecular fluids and solutions. It uses the inhomogeneous site-site direct correlation function of molecular fluid consistently constructed by nonlinear interpolation between the homogeneous ones. The site site correlations of the coexisting bulk phases are obtained from the reference interaction site model (RISM) integral equation with our closure approximation. For illustration, we calculated the structure of the planar liquid-vapor as well as liquid-liquid interfaces of n-hexane and methanol at ambient conditions.

Immersion-scanning-tunneling-microscope for long-term variable-temperature experiments at liquid-solid interfaces

NASA Astrophysics Data System (ADS)

Ochs, Oliver; Heckl, Wolfgang M.; Lackinger, Markus

2018-05-01

Fundamental insights into the kinetics and thermodynamics of supramolecular self-assembly on surfaces are uniquely gained by variable-temperature high-resolution Scanning-Tunneling-Microscopy (STM). Conventionally, these experiments are performed with standard ambient microscopes extended with heatable sample stages for local heating. However, unavoidable solvent evaporation sets a technical limit on the duration of these experiments, hence prohibiting long-term experiments. These, however, would be highly desirable to provide enough time for temperature stabilization and settling of drift but also to study processes with inherently slow kinetics. To overcome this dilemma, we propose a STM that can operate fully immersed in solution. The instrument is mounted onto the lid of a hermetically sealed heatable container that is filled with the respective solution. By closing the container, both the sample and microscope are immersed in solution. Thereby solvent evaporation is eliminated and an environment for long-term experiments with utmost stable and controllable temperatures between room-temperature and 100 °C is provided. Important experimental requirements for the immersion-STM and resulting design criteria are discussed, the strategy for protection against corrosive media is described, the temperature stability and drift behavior are thoroughly characterized, and first long-term high resolution experiments at liquid-solid interfaces are presented.

Dependence of solid-liquid interface free energy on liquid structure

NASA Astrophysics Data System (ADS)

Wilson, S. R.; Mendelev, M. I.

2014-09-01

The Turnbull relation is widely believed to enable prediction of solid-liquid interface (SLI) free energies from measurements of the latent heat and the solid density. Ewing proposed an additional contribution to the SLI free energy to account for variations in liquid structure near the interface. In the present study, molecular dynamics (MD) simulations were performed to investigate whether SLI free energy depends on liquid structure. Analysis of the MD simulation data for 11 fcc metals demonstrated that the Turnbull relation is only a rough approximation for highly ordered liquids, whereas much better agreement is observed with Ewing's theory. A modification to Ewing's relation is proposed in this study that was found to provide excellent agreement with MD simulation data.

Web-Based Interactive Electronic Technical Manual (IETM) Common User Interface Style Guide, Version 2.0

DTIC Science & Technology

2003-07-01

Technical Report WEB-BASED INTERACTIVE ELECTRONIC TECHNICAL MANUAL (IETM) COMMON USER INTERFACE STYLE GUIDE Version 2.0 – July 2003 by L. John Junod ...ACKNOWLEDGEMENTS The principal authors of this document were: John Junod – NSWC, Carderock Division, Phil Deuell – AMSEC LLC, Kathleen Moore

Cells on Gels: Cell Behavior at the Air-Gel Interface

NASA Astrophysics Data System (ADS)

O'Bryan, Christopher; Hormel, Tristan; Bhattacharjee, Tapomoy; Sawyer, W.; Angelini, Thomas

Numerous different types of cells are often grown at air-liquid interfaces. For example, a common way to create cell spheroids is to disperse cells in a droplet of liquid media that hangs from the lid of a culture dish - the ``hanging drop'' method. Some types of epithelial cells form monolayers at the bottom of hanging drops, instead of spheroids. Corneal epithelial cells stratify and exhibit a tissue-like phenotype when attached to liquid permeable culture surfaces positioned at the air-liquid media interface (air-lifted culture). These widely used culture methods make experimentation challenging - imaging through hanging drops and air-lifted culture dishes is prohibitive. However, similar results may be achieved by culturing cells on hydrogel surfaces at the air-gel interface. In this talk we will describe a method for culturing cells at air-gel interfaces. We seed human corneal epithelial cells (hTCEpi) onto the surfaces of hydrogel networks and jammed microgels, exposed to air. Preliminary observations of cell behavior at the air-gel interface will be presented.

Molecular dynamics study on condensation/evaporation coefficients of chain molecules at liquid-vapor interface

NASA Astrophysics Data System (ADS)

Nagayama, Gyoko; Takematsu, Masaki; Mizuguchi, Hirotaka; Tsuruta, Takaharu

2015-07-01

The structure and thermodynamic properties of the liquid-vapor interface are of fundamental interest for numerous technological implications. For simple molecules, e.g., argon and water, the molecular condensation/evaporation behavior depends strongly on their translational motion and the system temperature. Existing molecular dynamics (MD) results are consistent with the theoretical predictions based on the assumption that the liquid and vapor states in the vicinity of the liquid-vapor interface are isotropic. Additionally, similar molecular condensation/evaporation characteristics have been found for long-chain molecules, e.g., dodecane. It is unclear, however, whether the isotropic assumption is valid and whether the molecular orientation or the chain length of the molecules affects the condensation/evaporation behavior at the liquid-vapor interface. In this study, MD simulations were performed to study the molecular condensation/evaporation behavior of the straight-chain alkanes, i.e., butane, octane, and dodecane, at the liquid-vapor interface, and the effects of the molecular orientation and chain length were investigated in equilibrium systems. The results showed that the condensation/evaporation behavior of chain molecules primarily depends on the molecular translational energy and the surface temperature and is independent of the molecular chain length. Furthermore, the orientation at the liquid-vapor interface was disordered when the surface temperature was sufficiently higher than the triple point and had no significant effect on the molecular condensation/evaporation behavior. The validity of the isotropic assumption was confirmed, and we conclude that the condensation/evaporation coefficients can be predicted by the liquid-to-vapor translational length ratio, even for chain molecules.

Molecular dynamics study on condensation/evaporation coefficients of chain molecules at liquid-vapor interface.

PubMed

Nagayama, Gyoko; Takematsu, Masaki; Mizuguchi, Hirotaka; Tsuruta, Takaharu

2015-07-07

The structure and thermodynamic properties of the liquid-vapor interface are of fundamental interest for numerous technological implications. For simple molecules, e.g., argon and water, the molecular condensation/evaporation behavior depends strongly on their translational motion and the system temperature. Existing molecular dynamics (MD) results are consistent with the theoretical predictions based on the assumption that the liquid and vapor states in the vicinity of the liquid-vapor interface are isotropic. Additionally, similar molecular condensation/evaporation characteristics have been found for long-chain molecules, e.g., dodecane. It is unclear, however, whether the isotropic assumption is valid and whether the molecular orientation or the chain length of the molecules affects the condensation/evaporation behavior at the liquid-vapor interface. In this study, MD simulations were performed to study the molecular condensation/evaporation behavior of the straight-chain alkanes, i.e., butane, octane, and dodecane, at the liquid-vapor interface, and the effects of the molecular orientation and chain length were investigated in equilibrium systems. The results showed that the condensation/evaporation behavior of chain molecules primarily depends on the molecular translational energy and the surface temperature and is independent of the molecular chain length. Furthermore, the orientation at the liquid-vapor interface was disordered when the surface temperature was sufficiently higher than the triple point and had no significant effect on the molecular condensation/evaporation behavior. The validity of the isotropic assumption was confirmed, and we conclude that the condensation/evaporation coefficients can be predicted by the liquid-to-vapor translational length ratio, even for chain molecules.

Dynamic Mass Transfer of Hemoglobin at the Aqueous/Ionic-Liquid Interface Monitored with Liquid Core Optical Waveguide.

PubMed

Chen, Xuwei; Yang, Xu; Zeng, Wanying; Wang, Jianhua

2015-08-04

Protein transfer from aqueous medium into ionic liquid is an important approach for the isolation of proteins of interest from complex biological samples. We hereby report a solid-cladding/liquid-core/liquid-cladding sandwich optical waveguide system for the purpose of monitoring the dynamic mass-transfer behaviors of hemoglobin (Hb) at the aqueous/ionic liquid interface. The optical waveguide system is fabricated by using a hydrophobic IL (1,3-dibutylimidazolium hexafluorophosphate, BBimPF6) as the core, and protein solution as one of the cladding layer. UV-vis spectra are recorded with a CCD spectrophotometer via optical fibers. The recorded spectra suggest that the mass transfer of Hb molecules between the aqueous and ionic liquid media involve accumulation of Hb on the aqueous/IL interface followed by dynamic extraction/transfer of Hb into the ionic liquid phase. A part of Hb molecules remain at the interface even after the accomplishment of the extraction/transfer process. Further investigations indicate that the mass transfer of Hb from aqueous medium into the ionic liquid phase is mainly driven by the coordination interaction between heme group of Hb and the cationic moiety of ionic liquid, for example, imidazolium cation in this particular case. In addition, hydrophobic interactions also contribute to the transfer of Hb.

Investigation of surface charge density on solid-liquid interfaces by modulating the electrical double layer.

PubMed

Moon, Jong Kyun; Song, Myung Won; Pak, Hyuk Kyu

2015-05-20

A solid surface in contact with water or aqueous solution usually carries specific electric charges. These surface charges attract counter ions from the liquid side. Since the geometry of opposite charge distribution parallel to the solid-liquid interface is similar to that of a capacitor, it is called an electrical double layer capacitor (EDLC). Therefore, there is an electrical potential difference across an EDLC in equilibrium. When a liquid bridge is formed between two conducting plates, the system behaves as two serially connected EDLCs. In this work, we propose a new method for investigating the surface charge density on solid-liquid interfaces. By mechanically modulating the electrical double layers and simultaneously applying a dc bias voltage across the plates, an ac electric current can be generated. By measuring the voltage drop across a load resistor as a function of bias voltage, we can study the surface charge density on solid-liquid interfaces. Our experimental results agree very well with the simple equivalent electrical circuit model proposed here. Furthermore, using this method, one can determine the polarity of the adsorbed state on the solid surface depending on the material used. We expect this method to aid in the study of electrical phenomena on solid-liquid interfaces.

Product Development as a Fuzzy Interface between Technical and Non-technical Education.

ERIC Educational Resources Information Center

Masarnau, Juan

1988-01-01

Discusses a product development structure, including marketing, design, technology, industrial manufacturing, reasoning, and objects. Describes needs of the interface in terms of marketing, industrial design, technology, and industry. (YP)

Liquid lens enabling real-time focus and tilt compensation for optical image stabilization in camera modules

NASA Astrophysics Data System (ADS)

Simon, Eric; Craen, Pierre; Gaton, Hilario; Jacques-Sermet, Olivier; Laune, Frédéric; Legrand, Julien; Maillard, Mathieu; Tallaron, Nicolas; Verplanck, Nicolas; Berge, Bruno

2010-05-01

A new generation of liquid lenses based on electrowetting has been developed, using a multi-electrode design, enabling to induce optical tilt and focus corrections in the same component. The basic principle is to rely on a conical shape for supporting the liquid interface, the conical shape insuring a restoring force for the liquid liquid interface to come at the center position. The multi-electrode design enables to induce an average tilt of the liquid liquid interface when a bias voltage is applied to the different electrodes. This tilt is reversible, vanishing when voltage bias is cancelled. Possible application of this new lens component is the realization of miniature camera featuring auto-focus and optical image stabilization (OIS) without any mobile mechanical part. Experimental measurements of actual performances of liquid lens component will be presented : focus and tilt amplitude, residual optical wave front error and response time.

Gas-liquid two-phase flow pattern identification by ultrasonic echoes reflected from the inner wall of a pipe

NASA Astrophysics Data System (ADS)

Liang, Fachun; Zheng, Hongfeng; Yu, Hao; Sun, Yuan

2016-03-01

A novel ultrasonic pulse echo method is proposed for flow pattern identification in a horizontal pipe with gas-liquid two-phase flow. A trace of echoes reflected from the pipe’s internal wall rather than the gas-liquid interface is used for flow pattern identification. Experiments were conducted in a horizontal air-water two-phase flow loop. Two ultrasonic transducers with central frequency of 5 MHz were mounted at the top and bottom of the pipe respectively. The experimental results show that the ultrasonic reflection coefficient of the wall-gas interface is much larger than that of the wall-liquid interface due to the large difference in the acoustic impedance of gas and liquid. The stratified flow, annular flow and slug flow can be successfully recognized using the attenuation ratio of the echoes. Compared with the conventional ultrasonic echo measurement method, echoes reflected from the inner surface of a pipe wall are independent of gas-liquid interface fluctuation, sound speed, and gas and liquid superficial velocities, which makes the method presented a promising technique in field practice.

Electricity in foams: from one soapy interface to the macroscopic material

NASA Astrophysics Data System (ADS)

Biance, Anne-Laure

2017-11-01

Liquid foams (a dispersion of gas bubbles in a soapy solution) destabilize with time due to coarsening, coalescence and gravity driven drainage. We propose here to inhibit (or trigger) the foam destabilization by applying an electric field to the material. This effect is investigated at the different scales of the system: one soapy interface, one liquid film, the macroscopic foam. The generation of an electroosmotic flow near a soapy liquid/gas interface raises many issues. How does the flow affect surfactant repartition? Is there a Marangoni stress at the interface? At the scale of one soap film, how the electric field affects the film stability and deformation? In a macroscopic foam, one can wonder whether the electric field can indeed reverse gravity driven drainage and increase foam lifetime? These different issues are considered by developing new experimental techniques allowing us to probe surfactant repartition at liquid interfaces, soap film thicknesses and liquid foam properties when an electric field is applied. The results will be presented together with a comprehensive picture of the mechanisms arising at each scale of the material, to conclude with the potential use of electricity in liquid foams to control destabilization. Collaborators: Baptiste Blanc, Oriane Bonhomme, Laurent Joly, Christophe Ybert.

Interface structure between tetraglyme and graphite

NASA Astrophysics Data System (ADS)

Minato, Taketoshi; Araki, Yuki; Umeda, Kenichi; Yamanaka, Toshiro; Okazaki, Ken-ichi; Onishi, Hiroshi; Abe, Takeshi; Ogumi, Zempachi

2017-09-01

Clarification of the details of the interface structure between liquids and solids is crucial for understanding the fundamental processes of physical functions. Herein, we investigate the structure of the interface between tetraglyme and graphite and propose a model for the interface structure based on the observation of frequency-modulation atomic force microscopy in liquids. The ordering and distorted adsorption of tetraglyme on graphite were observed. It is found that tetraglyme stably adsorbs on graphite. Density functional theory calculations supported the adsorption structure. In the liquid phase, there is a layered structure of the molecular distribution with an average distance of 0.60 nm between layers.

Solid/liquid interfacial free energies in binary systems

NASA Technical Reports Server (NTRS)

Nason, D.; Tiller, W. A.

1973-01-01

Description of a semiquantitative technique for predicting the segregation characteristics of smooth interfaces between binary solid and liquid solutions in terms of readily available thermodynamic parameters of the bulk solutions. A lattice-liquid interfacial model and a pair-bonded regular solution model are employed in the treatment with an accommodation for liquid interfacial entropy. The method is used to calculate the interfacial segregation and the free energy of segregation for solid-liquid interfaces between binary solutions for the (111) boundary of fcc crystals. The zone of compositional transition across the interface is shown to be on the order of a few atomic layers in width, being moderately narrower for ideal solutions. The free energy of the segregated interface depends primarily upon the solid composition and the heats of fusion of the component atoms, the composition difference of the solutions, and the difference of the heats of mixing of the solutions.

Phase transition detection by surface photo charge effect in liquid crystals

NASA Astrophysics Data System (ADS)

Ivanov, O.; Petrov, M.; Naradikian, H.; Perez-Diaz, J. L.

2018-05-01

The surface photo charge effect (SPCE) was applied for the first time at structure and phase transitions study of hydrogen bonded in dimer liquid crystals (HBDLCs). Due to the high sensitivity of this method, besides first-order phase transitions, characteristic for the p,n-octyloxibenzoic acids (8OBA), an order transition was definitely detected within the nematic range. We state that the SPCE, arising at the solid-HBDLCs interface due to the double electrical layer, is invariably concomitant with solid surface-liquid interfaces, and indicates that the changes of the characteristics of this layer, under incident optical irradiation, induce surface charge rearrangement and alternating potential difference. A mechanism of induction of the SPCE at the interface of solid surface-anisotropic liquids is proposed. We also indicate that this mechanism can be adapted for solid surface-isotropic liquid interface, including colloids (milk) and fog (aerosols)-condensed medium.

Liquid-vapor interface locations in a spheroidal container under low gravity

NASA Technical Reports Server (NTRS)

Carney, M. J.

1986-01-01

As a part of the general study of liquid behavior in low gravity environments, an experimental investigation was conducted to determine if there are equilibrium liquid-vapor interface configurations that can exist at more than one location in oblate spheroidal containers under reduced gravity conditions. Static contact angles of the test liquids on the spheroid surface were restricted to near 0 deg. The experiments were conducted in a low gravity environment. An oblate spheroidal tank was tested with an eccentricity of 0.68 and a semimajor axis of 2.0 cm. Both quantitative and qualitative data were obtained on the liquid-vapor interface configuration and position inside the container. The results of these data, and their impat on previous work in this area, are discussed. Of particular interest are those equilibrium interface configurations that can exist at multiple locations in the container.

Scale effect of slip boundary condition at solid–liquid interface

PubMed Central

Nagayama, Gyoko; Matsumoto, Takenori; Fukushima, Kohei; Tsuruta, Takaharu

2017-01-01

Rapid advances in microelectromechanical systems have stimulated the development of compact devices, which require effective cooling technologies (e.g., microchannel cooling). However, the inconsistencies between experimental and classical theoretical predictions for the liquid flow in microchannel remain unclarified. Given the larger surface/volume ratio of microchannel, the surface effects increase as channel scale decreases. Here we show the scale effect of the boundary condition at the solid–liquid interface on single-phase convective heat transfer characteristics in microchannels. We demonstrate that the deviation from classical theory with a reduction in hydraulic diameters is due to the breakdown of the continuum solid–liquid boundary condition. The forced convective heat transfer characteristics of single-phase laminar flow in a parallel-plate microchannel are investigated. Using the theoretical Poiseuille and Nusselt numbers derived under the slip boundary condition at the solid–liquid interface, we estimate the slip length and thermal slip length at the interface. PMID:28256536

Attachment of composite porous supra-particles to air-water and oil-water interfaces: theory and experiment.

PubMed

Paunov, Vesselin N; Al-Shehri, Hamza; Horozov, Tommy S

2016-09-29

We developed and tested a theoretical model for the attachment of fluid-infused porous supra-particles to a fluid-liquid interface. We considered the wetting behaviour of agglomerated clusters of particles, typical of powdered materials dispersed in a liquid, as well as of the adsorption of liquid-infused colloidosomes at the liquid-fluid interface. The free energy of attachment of a composite spherical porous supra-particle made from much smaller aggregated spherical particles to the oil-water interface was calculated. Two cases were considered: (i) a water-filled porous supra-particle adsorbed at the oil-water interface from the water phase, and, (ii) an oil-filled porous supra-particle adsorbed at the oil-water interface from the oil-phase. We derived equations relating the three-phase contact angle of the smaller "building block" particles and the contact angle of the liquid-infused porous supra-particles. The theory predicts that the porous supra-particle contact angle attached at the liquid interface strongly depends on the type of fluid infused in the particle pores and the fluid phase from which it approaches the liquid interface. We tested the theory by using millimetre-sized porous supra-particles fabricated by evaporation of droplets of polystyrene latex suspension on a pre-heated super-hydrophobic surface, followed by thermal annealing at the glass transition temperature. Such porous particles were initially infused with water or oil and approached to the oil-water interface from the infusing phase. The experiment showed that when attaching at the hexadecane-water interface, the porous supra-particles behaved as hydrophilic when they were pre-filled with water and hydrophobic when they were pre-filled with hexadecane. The results agree with the theoretically predicted contact angles for the porous composite supra-particles based on the values of the contact angles of their building block latex particles measured with the Gel Trapping Technique. The experimental data for the attachment of porous supra particles to the air-water interface from both air and water also agree with the theoretical model. This study gives important insights about how porous particles and particle aggregates attach to the oil-water interface in Pickering emulsions and the air-water surface in particle-stabilised aqueous foams relevant in ore flotation and a range of cosmetic, pharmaceutical, food, home and personal care formulations.

Liquid?solid helium interface: some conceptual questions

NASA Astrophysics Data System (ADS)

Leggett, A. J.

2003-12-01

I raise, and discuss qualitatively, some conceptual issues concerning the interface between the crystalline solid and superfluid liquid phases of 4He emphasizing, in particular, the fact that the ground-state wave functions of the two phases are prima facie qualitatively quite different, in that the superfluid liquid phase possesses off-diagonal long-range order (ODLRO), while the crystalline solid does not. The fact that the statics and dynamics of the interface do not appear to be particularly sensitive to the presence of ODLRO in the liquid is tentatively explained by the fact that because of a subtlety associated with the Bose statistics obeyed by the atoms, the solid and liquid wave functions are not locally very different.

Ordering Transitions in Liquid Crystals Permit Imaging of Spatial and Temporal Patterns Formed by Proteins Penetrating into Lipid-Laden Interfaces

PubMed Central

Daschner De Tercero, Maren; Abbott, Nicholas L.

2013-01-01

Recent studies have reported that full monolayers of L-α-dilaurylphosphatidylcholine (L-DLPC) and D-α-dipalmitoylphosphatidylcholine (D-DPPC) formed at interfaces between thermotropic liquid crystals (LCs) and aqueous phases lead to homeotropic (perpendicular) orientations of nematic LCs and that specific binding of proteins to these interfaces (such as phospholipase A2 binding to D-DPPC) can trigger orientational ordering transitions in the liquid crystals. We report on the nonspecific interactions of proteins with aqueous-LC interfaces decorated with partial monolayer coverage of L-DLPC. Whereas nonspecific interactions of four proteins (cytochrome c, bovine serum albumin,immunoglobulins, and neutravidin) do not perturb the ordering of the LC when a full monolayer of L-DLPC is assembled at the aqueous-LC interface, we observe patterned orientational transitions in the LC that reflect penetration of proteins into the interface of the LC with partial monolayer coverage of L-DLPC. The spatial patterns formed by the proteins and lipids at the interface are surprisingly complex, and in some cases the protein domains are found to compartmentalize lipid within the interfaces. These results suggest that phospholipid-decorated interfaces between thermotropic liquid crystals and aqueous phases offer the basis of a simple and versatile tool to study the spatial organization and dynamics ofprotein networks formed at mobile, lipid-decorated interfaces. PMID:23671353

Dependence of solid-liquid interface free energy on liquid structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilson, S R; Mendelev, M I

2014-09-01

The Turnbull relation is widely believed to enable prediction of solid–liquid interface (SLI) free energies from measurements of the latent heat and the solid density. Ewing proposed an additional contribution to the SLI free energy to account for variations in liquid structure near the interface. In the present study, molecular dynamics (MD) simulations were performed to investigate whether SLI free energy depends on liquid structure. Analysis of the MD simulation data for 11 fcc metals demonstrated that the Turnbull relation is only a rough approximation for highly ordered liquids, whereas much better agreement is observed with Ewing’s theory. A modificationmore » to Ewing’s relation is proposed in this study that was found to provide excellent agreement with MD simulation data.« less

Vapor-liquid-solid growth of silicon and silicon germanium nanowires

NASA Astrophysics Data System (ADS)

Nimmatoori, Pramod

2009-12-01

Si and Si1-xGex nanowires are promising materials with potential applications in various disciplines of science and technology. Small diameter nanowires can act as model systems to study interesting phenomena such as tunneling that occur in the nanometer regime. Furthermore, technical challenges in fabricating nanoscale size devices from thin films have resulted in interest and research on nanowires. In this perspective, vertical integrated nanowire field effect transistors (VINFETs) fabricated from Si nanowires are promising devices that offer better control on device properties and push the transistor architecture into the third dimension potentially enabling ultra-high transistor density circuits. Transistors fabricated from Si/Si 1-xGex nanowires have also been proposed that can have high carrier mobility. In addition, the Si and Si1-xGe x nanowires have potential to be used in various applications such as sensing, thermoelectrics and solar cells. Despite having considerable potential, the understanding of the vapor-liquid-solid (VLS) mechanism utilized to fabricate these wires is still rudimentary. Hence, the objective of this thesis is to understand the effects of nanoscale size and the role of catalyst that mediates the wire growth on the growth rate of Si and Si1-xGe x nanowires and interfacial abruptness in Si/Si1-xGe x axial heterostructure nanowires. Initially, the growth and structural properties of Si nanowires with tight diameter distribution grown from 10, 20 and 50 nm Au particles dispersed on a polymer-modified substrate was studied. A nanoparticle application process was developed to disperse Au particles on the substrate surface with negligible agglomeration and sufficient density. The growth temperature and SiH4 partial pressure were varied to optimize the growth conditions amenable to VLS growth with smooth wire morphology and negligible Si thin film deposition on wire sidewalls. The Si nanowire growth rate was studied as a function of growth time, temperature, SiH4 partial pressure and wire diameter and discussed in the context of the literature. The wire growth rate was found to increase with wire diameter in agreement with a size-related effect known as the Gibbs-Thomson effect. Subsequently, the effect of P and Sb doping on the growth rate and structural properties of Si nanowires was investigated. A reduction in wire growth rate was observed upon doping, which was pronounced in case of Sb doping, ascribable to P/Sb segregation at the vapor-liquid interface (catalyst surface) and the liquid-solid interface (growth front) that in turn reduces Si incorporation at these interfaces. The second part of thesis was focused on the Si1-xGe x alloy nanowires. The effect of wire diameter and growth conditions on the interfacial abruptness of Si/Si1-xGex heterostructure nanowires was examined. Abrupt interfaces were obtained at smaller wire diameters. However, the growth temperature wasn't found to have much impact on the interfacial abruptness. These results were explained in terms of catalyst effects on the interfacial abruptness. The remaining part of the study was focused on the effect of growth conditions on the growth rate of Si1-x Gex nanowires. It was found that the Si incorporation mechanism was different between Si and Si1-xGex nanowire growth which was ascribed to changes in the gas phase or catalyst composition that can impact the SiH4 decomposition kinetics at the catalyst surface (vapor-liquid interface) and/or Si incorporation at the growth front (liquid-solid interface).

Unique orientations and rotational dynamics of a 1-butyl-3-methyl-imidazolium hexafluorophosphate ionic liquid at the gas-liquid interface: the effects of the hydrogen bond and hydrophobic interactions.

PubMed

Yang, Deshuai; Fu, Fangjia; Li, Li; Yang, Zhen; Wan, Zheng; Luo, Yi; Hu, Na; Chen, Xiangshu; Zeng, Guixiang

2018-05-07

Here we report a series of molecular dynamics simulations for the orientations and rotational dynamics of the 1-butyl-3-methyl-imidazoliumhexafluorophosphate ([BMIM][PF 6 ]) ionic liquid (IL) at the gas-liquid interface. Compared to the bulk phase, the [BMIM] + cations at the interface prefer to orientate themselves with their imidazolium rings perpendicular to the gas-IL interface plane and their butyl chains pointing toward the vacuum phase. Such a preferential orientation can be attributed to the combined effect of the hydrophobic interactions and the optimum loss of hydrogen bonds (HBs). More interestingly, our simulation results demonstrate that the butyl chains of cations exhibit a two-stage rotational behavior at the interface, where the butyl chains are always in the vacuum phase at the first stage and the second stage corresponds to the butyl chains migrating from the vacuum phase into the liquid phase. A further detailed analysis reveals that their rotational motions at the first stage are mainly determined by the weakened HB strength at the interface while those at the second stage are dominated by their hydrophobic interactions. Such a unique rotational behavior of the butyl chains is significantly different from those of the anions and the imidazolium rings of cations at the interface due to the lack of existence of hydrophobic interaction in the cases of the latter two. In addition, a new and simple time correlation function (TCF) was constructed here for the first time to quantitatively identify the relevant hydrophobic interaction of alkyl chains. Therefore, our simulation results provide a molecular-level understanding of the effects of HB and hydrophobic interactions on the unique properties of imidazolium-based ILs at the gas-liquid interface.

Critical Evaluation of Air-Liquid Interface Exposure Devices for In Vitro Assessment of Atmospheric Pollutants

EPA Science Inventory

Exposure of cells to atmospheric pollutants at the air-liquid interface (ALI) is a more realistic approach than exposures of attached cells submerged in liquid medium. However, there is still limited understanding of the ideal ALI device design features that permit reproducible a...

Understanding Air-Liquid Interface Cell Exposure Systems: A Comprehensive Assessment of Various Systems Under Identical Conditions

EPA Science Inventory

Exposure of cells to atmospheric pollutants at the air-liquid interface (ALI) is a more realistic approach than exposures of attached cells submerged in liquid medium. However, there is still limited understanding of the ideal ALI system design features that permit reproducible a...

Water at Interfaces.

PubMed

Björneholm, Olle; Hansen, Martin H; Hodgson, Andrew; Liu, Li-Min; Limmer, David T; Michaelides, Angelos; Pedevilla, Philipp; Rossmeisl, Jan; Shen, Huaze; Tocci, Gabriele; Tyrode, Eric; Walz, Marie-Madeleine; Werner, Josephina; Bluhm, Hendrik

2016-07-13

The interfaces of neat water and aqueous solutions play a prominent role in many technological processes and in the environment. Examples of aqueous interfaces are ultrathin water films that cover most hydrophilic surfaces under ambient relative humidities, the liquid/solid interface which drives many electrochemical reactions, and the liquid/vapor interface, which governs the uptake and release of trace gases by the oceans and cloud droplets. In this article we review some of the recent experimental and theoretical advances in our knowledge of the properties of aqueous interfaces and discuss open questions and gaps in our understanding.

Particle self-assembly at ionic liquid-based interfaces.

PubMed

Frost, Denzil S; Nofen, Elizabeth M; Dai, Lenore L

2014-04-01

This review presents an overview of the nature of ionic liquid (IL)-based interfaces and self-assembled particle morphologies of IL-in-water, oil- and water-in-IL, and novel IL-in-IL Pickering emulsions with emphasis on their unique phenomena, by means of experimental and computational studies. In IL-in-water Pickering emulsions, particles formed monolayers at ionic liquid-water interfaces and were close-packed on fully covered emulsion droplets or aggregated on partially covered droplets. Interestingly, other than equilibrating at the ionic liquid-water interfaces, microparticles with certain surface chemistries were extracted into the ionic liquid phase with a high efficiency. These experimental findings were supported by potential of mean force calculations, which showed large energy drops as hydrophobic particles crossed the interface into the IL phase. In the oil- and water-in-IL Pickering emulsions, microparticles with acidic surface chemistries formed monolayer bridges between the internal phase droplets rather than residing at the oil/water-ionic liquid interfaces, a significant deviation from traditional Pickering emulsion morphology. Molecular dynamics simulations revealed aspects of the mechanism behind this bridging phenomenon, including the role of the droplet phase, surface chemistry, and inter-particle film. Novel IL-in-IL Pickering emulsions exhibited an array of self-assembled morphologies including the previously observed particle absorption and bridging phenomena. The appearance of these morphologies depended on the particle surface chemistry as well as the ILs used. The incorporation of particle self-assembly with ionic liquid science allows for new applications at the intersection of these two fields, and have the potential to be numerous due to the tunability of the ionic liquids and particles incorporated, as well as the particle morphology by combining certain groups of particle surface chemistry, IL type (protic or aprotic), and whether oil or water is incorporated. © 2013.

Nanoparticle Assemblies at Fluid Interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Russell, Thomas P.

2015-03-10

A systematic study of the structure and dynamics of nanoparticles (NP) and NP-surfactants was performed. The ligands attached to both the NPs and NP-surfactants dictate the manner in which the nanoscopic materials assemble at fluid interfaces. Studies have shown that a single layer of the nanoscpic materials form at the interface to reduce the interactions between the two immiscible fluids. The shape of the NP is, also, important, where for spherical particles, a disordered, liquid-like monolayer forms, and, for nanorods, ordered domains at the interface is found and, if the monolayers are compressed, the orientation of the nanorods with respectmore » to the interface can change. By associating end-functionalized polymers to the NPs assembled at the interface, NP-surfactants are formed that increase the energetic gain in segregating each NP at the interface which allows the NP-surfactants to jam at the interface when compressed. This has opened the possibility of structuring the two liquids by freezing in shape changes of the liquids.« less

The liquid crystal light valve, an optical-to-optical interface device

NASA Technical Reports Server (NTRS)

Jacobson, A. D.; Beard, T. D.; Bleha, W. P.; Margerum, J. D.; Wong, S. Y.

1972-01-01

A photoactivated liquid crystal light valve is described as an optical-to-optical interface device (OTTO) which is designed to transfer an optical image from a noncoherent light beam to a spatially coherent beam of light, in real time. Schematics of OTTO in use, the liquid cyrstal cell, and the liquid crystal structure are presented. Sensitivity characteristics and the principles of operation are discussed.

State-resolved Thermal/Hyperthermal Dynamics of Atmospheric Species

DTIC Science & Technology

2015-06-23

gas -room temperature ionic liquid (RTIL) interfaces. 2) Large scale trajectory simulations for theoretical analysis of gas - liquid scattering studies...areas: 1) Diode laser and LIF studies of hyperthermal CO2 and NO collisions at the gas -room temperature ionic liquid (RTIL) interfaces. 2) Large...scale trajectory simulations for theoretical analysis of gas - liquid scattering studies, 3) LIF data for state-resolved scattering of hyperthermal NO at

Superhydrophobic-like tunable droplet bouncing on slippery liquid interfaces

PubMed Central

Hao, Chonglei; Li, Jing; Liu, Yuan; Zhou, Xiaofeng; Liu, Yahua; Liu, Rong; Che, Lufeng; Zhou, Wenzhong; Sun, Dong; Li, Lawrence; Xu, Lei; Wang, Zuankai

2015-01-01

Droplet impacting on solid or liquid interfaces is a ubiquitous phenomenon in nature. Although complete rebound of droplets is widely observed on superhydrophobic surfaces, the bouncing of droplets on liquid is usually vulnerable due to easy collapse of entrapped air pocket underneath the impinging droplet. Here, we report a superhydrophobic-like bouncing regime on thin liquid film, characterized by the contact time, the spreading dynamics, and the restitution coefficient independent of underlying liquid film. Through experimental exploration and theoretical analysis, we demonstrate that the manifestation of such a superhydrophobic-like bouncing necessitates an intricate interplay between the Weber number, the thickness and viscosity of liquid film. Such insights allow us to tune the droplet behaviours in a well-controlled fashion. We anticipate that the combination of superhydrophobic-like bouncing with inherent advantages of emerging slippery liquid interfaces will find a wide range of applications. PMID:26250403

Investigation the evaporation-condensation problem by means of the joint numerical solution of the Boltzmann kinetic equation and interface modelling

NASA Astrophysics Data System (ADS)

Shiskova, I. N.; Kryukov, A. P.; Levashov, V. Yu

2017-11-01

The paper is devoted to research of the heat and mass transfer processes in liquid and vapor phase on the basis of the uniform approach assuming the through description of liquid, interface and vapor. Multiparticles interactions in liquid will be taken into account. The problem is studied when temperature in the depth of liquid differs from temperature in the vapor region. In this case there are both mass flux and heat flux. The study of influence of the correlations resulting from interactions of molecules set in thin near-surface liquid layers and an interface on intensity of evaporation is made. As a result of calculations the equilibrium line of the liquid-vapor saturation is obtained, which corresponds good enough with experimental data. Distributions of density, temperature, pressure, heat and mass fluxes, both in a liquid and in vapor are also presented.

Mobile interfaces: Liquids as a perfect structural material for multifunctional, antifouling surfaces

DOE PAGES

Grinthal, Alison; Aizenberg, Joanna

2013-10-14

Life creates some of its most robust, extreme surface materials not from solids but from liquids: a purely liquid interface, stabilized by underlying nanotexture, makes carnivorous plant leaves ultraslippery, the eye optically perfect and dirt-resistant, our knees lubricated and pressure-tolerant, and insect feet reversibly adhesive and shape-adaptive. Novel liquid surfaces based on this idea have recently been shown to display unprecedented omniphobic, self-healing, anti-ice, antifouling, optical, and adaptive properties. In this Perspective, we present a framework and a path forward for developing and designing such liquid surfaces into sophisticated, versatile multifunctional materials. Drawing on concepts from solid materials design andmore » fluid dynamics, we outline how the continuous dynamics, responsiveness, and multiscale patternability of a liquid surface layer can be harnessed to create a wide range of unique, active interfacial functions-able to operate in harsh, changing environments-not achievable with static solids. We discuss how, in partnership with the underlying substrate, the liquid surface can be programmed to adaptively and reversibly reconfigure from a defect-free, molecularly smooth, transparent interface through a range of finely tuned liquid topographies in response to environmental stimuli. In conclusion, with nearly unlimited design possibilities and unmatched interfacial properties, liquid materials-as long-term stable interfaces yet in their fully liquid state-may potentially transform surface design everywhere from medicine to architecture to energy infrastructure.« less

Nonequilibrium kinetic boundary condition at the vapor-liquid interface of argon

NASA Astrophysics Data System (ADS)

Ishiyama, Tatsuya; Fujikawa, Shigeo; Kurz, Thomas; Lauterborn, Werner

2013-10-01

A boundary condition for the Boltzmann equation (kinetic boundary condition, KBC) at the vapor-liquid interface of argon is constructed with the help of molecular dynamics (MD) simulations. The KBC is examined at a constant liquid temperature of 85 K in a wide range of nonequilibrium states of vapor. The present investigation is an extension of a previous one by Ishiyama, Yano, and Fujikawa [Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.95.084504 95, 084504 (2005)] and provides a more complete form of the KBC. The present KBC includes a thermal accommodation coefficient in addition to evaporation and condensation coefficients, and these coefficients are determined in MD simulations uniquely. The thermal accommodation coefficient shows an anisotropic behavior at the interface for molecular velocities normal versus tangential to the interface. It is also found that the evaporation and condensation coefficients are almost constant in a fairly wide range of nonequilibrium states. The thermal accommodation coefficient of the normal velocity component is almost unity, while that of the tangential component shows a decreasing function of the density of vapor incident on the interface, indicating that the tangential velocity distribution of molecules leaving the interface into the vapor phase may deviate from the tangential parts of the Maxwell velocity distribution at the liquid temperature. A mechanism for the deviation of the KBC from the isotropic Maxwell KBC at the liquid temperature is discussed in terms of anisotropic energy relaxation at the interface. The liquid-temperature dependence of the present KBC is also discussed.

3-Dimensional atomic scale structure of the ionic liquid-graphite interface elucidated by AM-AFM and quantum chemical simulations

NASA Astrophysics Data System (ADS)

Page, Alister J.; Elbourne, Aaron; Stefanovic, Ryan; Addicoat, Matthew A.; Warr, Gregory G.; Voïtchovsky, Kislon; Atkin, Rob

2014-06-01

In situ amplitude modulated atomic force microscopy (AM-AFM) and quantum chemical simulations are used to resolve the structure of the highly ordered pyrolytic graphite (HOPG)-bulk propylammonium nitrate (PAN) interface with resolution comparable with that achieved for frozen ionic liquid (IL) monolayers using STM. This is the first time that (a) molecular resolution images of bulk IL-solid interfaces have been achieved, (b) the lateral structure of the IL graphite interface has been imaged for any IL, (c) AM-AFM has elucidated molecular level structure immersed in a viscous liquid and (d) it has been demonstrated that the IL structure at solid surfaces is a consequence of both thermodynamic and kinetic effects. The lateral structure of the PAN-graphite interface is highly ordered and consists of remarkably well-defined domains of a rhomboidal superstructure composed of propylammonium cations preferentially aligned along two of the three directions in the underlying graphite lattice. The nanostructure is primarily determined by the cation. Van der Waals interactions between the propylammonium chains and the surface mean that the cation is enriched in the surface layer, and is much less mobile than the anion. The presence of a heterogeneous lateral structure at an ionic liquid-solid interface has wide ranging ramifications for ionic liquid applications, including lubrication, capacitive charge storage and electrodeposition.In situ amplitude modulated atomic force microscopy (AM-AFM) and quantum chemical simulations are used to resolve the structure of the highly ordered pyrolytic graphite (HOPG)-bulk propylammonium nitrate (PAN) interface with resolution comparable with that achieved for frozen ionic liquid (IL) monolayers using STM. This is the first time that (a) molecular resolution images of bulk IL-solid interfaces have been achieved, (b) the lateral structure of the IL graphite interface has been imaged for any IL, (c) AM-AFM has elucidated molecular level structure immersed in a viscous liquid and (d) it has been demonstrated that the IL structure at solid surfaces is a consequence of both thermodynamic and kinetic effects. The lateral structure of the PAN-graphite interface is highly ordered and consists of remarkably well-defined domains of a rhomboidal superstructure composed of propylammonium cations preferentially aligned along two of the three directions in the underlying graphite lattice. The nanostructure is primarily determined by the cation. Van der Waals interactions between the propylammonium chains and the surface mean that the cation is enriched in the surface layer, and is much less mobile than the anion. The presence of a heterogeneous lateral structure at an ionic liquid-solid interface has wide ranging ramifications for ionic liquid applications, including lubrication, capacitive charge storage and electrodeposition. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01219d

Nonlinear vibrational spectroscopy of surfactants at liquid interfaces

NASA Astrophysics Data System (ADS)

Miranda, Paulo Barbeitas

Surfactants are widely used to modify physical and chemical properties of interfaces. They play an important role in many technological problems. Surfactant monolayers are also of great scientific interest because they are two-dimensional systems that may exhibit a very rich phase transition behavior and can also be considered as a model system for biological interfaces. In this Thesis, we use a second-order nonlinear optical technique (Sum-Frequency Generation - SFG) to obtain vibrational spectra of surfactant monolayers at liquid/vapor and solid/liquid interfaces. The technique has several advantages: it is intrinsically surface-specific, can be applied to buried interfaces, has submonolayer sensitivity and is remarkably sensitive to the conformational order of surfactant monolayers. The first part of the Thesis is concerned with surfactant monolayers at the air/water interface (Langmuir films). Surface crystallization of an alcohol Langmuir film and of liquid alkanes are studied and their phase transition behaviors are found to be of different nature, although driven by similar intermolecular interactions. The effect of crystalline order of Langmuir monolayers on the interfacial water structure is also investigated. It is shown that water forms a well-ordered hydrogen-bonded network underneath an alcohol monolayer, in contrast to a fatty acid monolayer which induces a more disordered structure. In the latter case, ionization of the monolayer becomes more significant with increase of the water pH value, leading to an electric-field-induced ordering of interfacial water molecules. We also show that the orientation and conformation of fairly complicated molecules in a Langmuir monolayer can be completely mapped out using a combination of SFG and second harmonic generation (SHG). For a quantitative analysis of molecular orientation at an interface, local-field corrections must be included. The second part is a study of self-assembled surfactant monolayers at the solid/liquid interface. It is shown that the conformation of a monolayer adsorbed onto a solid substrate and immersed in a liquid is highly dependent on the monolayer surface density and on the nature of intermolecular interactions in the liquid. Fully packed monolayers are well ordered in any environment due to strong surfactant-surfactant interactions and limited liquid penetration into the monolayer. In contrast, loosely packed monolayers are very sensitive to the liquid environment. Non-polar liquids cause a mild increase in the surfactant conformational disorder. Polar liquids induce more disorder and hydrogen-bonding liquids produce highly disordered conformations due to the hydrophobic effect. When immersed in alkanes, under certain conditions the surfactant chains may become highly ordered due to their interaction with the liquid molecules (chain-chain interaction). In the case of long-chain alcohols, competition between the hydrophobic effect and chain-chain interaction is observed.

Behavior of ceramic particles at the solid-liquid metal interface in metal matrix composites

NASA Technical Reports Server (NTRS)

Stefanescu, D. M.; Dhindaw, B. K.; Kacar, S. A.; Moitra, A.

1988-01-01

Directional solidification results were obtained in order to investigate particle behavior at the solid-liquid interface in Al-2 pct Mg (cellular interface) and Al-6.1 pct Ni (eutectic interface) alloys. It is found that particles can be entrapped in the solid if adequate solidification rates and temperature gradients are used. Model results showed critical velocity values slightly higher than those obtained experimentally.

Microgravity

NASA Image and Video Library

1995-10-20

Interface Configuration Experiment on the Second United States Microgravity Laboratory (USML-2). Over time the photos show a change in the shape of the interface between a liquid and a gas in a sealed, slightly asymmetrical container. Under the force of Earth's gravity, the interface would remain nearly flat, but in microgravity, the interface shape and location changes significantly in the container, resulting in major shifts of liquid arising from small asymmetries in the container shape.

Electrodeposition of Polymer Nanostructures using Three Diffuse Double Layers: Polymerization beyond the Liquid/Liquid Interfaces

NASA Astrophysics Data System (ADS)

Divya, Velpula; Sangaranarayanan, M. V.

2018-04-01

Nanostructured conducting polymers have received immense attention during the past few decades on account of their phenomenal usefulness in diverse contexts, while the interface between two immiscible liquids is of great interest in chemical and biological applications. Here we propose a novel Electrode(solid)/Electrolyte(aqueous)/Electrolyte(organic) Interfacial assembly for the synthesis of polymeric nanostructures using a novel concept of three diffuse double layers. There exist remarkable differences between the morphologies of the polymers synthesized using the conventional electrode/electrolyte method and that of the new approach. In contrast to the commonly employed electrodeposition at liquid/liquid interfaces, these polymer modified electrodes can be directly employed in diverse applications such as sensors, supercapacitors etc.

Forces between a rigid probe particle and a liquid interface. II. The general case.

PubMed

Dagastine, R R; White, L R

2002-03-15

The semianalytic theory developed previously (Chan, D. Y. C., Dagastine, R. R., and White, L. R., J. Colloid Interface Sci. 236, 141 (2001)) to predict the force curve of an AFM measurement at a liquid interface using a colloidal probe has been expanded to incorporate a general force law with both attractive and repulsive forces. Expressions for the gradient of the force curve are developed to calculate the point at which the probe particle on the cantilever will spontaneously jump in toward the liquid interface. The calculation of the jump instability is reduced to a straightforward embroidery of the simple algorithms presented in Chan et al. In a variety of sample calculations using force laws including van der Waals, electrostatic, and hydrophobic forces for both oil/water and bubble/water interfaces, we have duplicated the general behaviors observed in several AFM investigations at liquid interfaces. The behavior of the drop as a Hookean spring and the numerical difficulties of a full numerical calculation of F(deltaX) are also discussed.

ρ-VOF: An interface sharpening method for gas-liquid flow simulation

NASA Astrophysics Data System (ADS)

Wang, Jiantao; Liu, Gang; Jiang, Xiong; Mou, Bin

2018-05-01

The study on simulation of compressible gas-liquid flow remains open. Popular methods are either confined to incompressible flow regime, or inevitably induce smear of the free interface. A new finite volume method for compressible two-phase flow simulation is contributed for this subject. First, the “heterogeneous equilibrium” assumption is introduced to the control volume, by hiring free interface reconstruction technology, the distribution of each component in the control volume is achieved. Next, AUSM+-up (advection upstream splitting method) scheme is employed to calculate the convective fluxes and pressure fluxes, with the contact discontinuity characteristic considered, followed by the update of the whole flow field. The new method features on density-based pattern and interface reconstruction technology from VOF (volume of fluid), thus we name it “ρ-VOF method”. Inherited from AUSM families and VOF, ρ-VOF behaves as an all-speed method, capable of simulating shock in gas-liquid flow, and preserving the sharpness of the free interface. Gas-liquid shock tube is simulated to evaluate the method, from which good agreement is obtained between the predicted results and those of the cited literature, meanwhile, sharper free interface is identified. Finally, the capability and validity of ρ-VOF method can be concluded in compressible gas-liquid flow simulation.

Electrical control of Faraday rotation at a liquid-liquid interface.

PubMed

Marinescu, Monica; Kornyshev, Alexei A; Flatté, Michael E

2015-01-01

A theory is developed for the Faraday rotation of light from a monolayer of charged magnetic nanoparticles at an electrified liquid-liquid interface. The polarization fields of neighboring nanoparticles enhance the Faraday rotation. At such interfaces, and for realistic sizes and charges of nanoparticles, their adsorption-desorption can be controlled with a voltage variation<1 V, providing electrovariable Faraday rotation. A calculation based on the Maxwell-Garnett theory predicts that the corresponding redistribution of 40 nm nanoparticles of yttrium iron garnet can switch a cavity with a quality factor larger than 10(4) for light of wavelength 500 nm at normal incidence.

Linear Stability Analysis of an Acoustically Vaporized Droplet

NASA Astrophysics Data System (ADS)

Siddiqui, Junaid; Qamar, Adnan; Samtaney, Ravi

2015-11-01

Acoustic droplet vaporization (ADV) is a phase transition phenomena of a superheat liquid (Dodecafluoropentane, C5F12) droplet to a gaseous bubble, instigated by a high-intensity acoustic pulse. This approach was first studied in imaging applications, and applicable in several therapeutic areas such as gas embolotherapy, thrombus dissolution, and drug delivery. High-speed imaging and theoretical modeling of ADV has elucidated several physical aspects, ranging from bubble nucleation to its subsequent growth. Surface instabilities are known to exist and considered responsible for evolving bubble shapes (non-spherical growth, bubble splitting and bubble droplet encapsulation). We present a linear stability analysis of the dynamically evolving interfaces of an acoustically vaporized micro-droplet (liquid A) in an infinite pool of a second liquid (liquid B). We propose a thermal ADV model for the base state. The linear analysis utilizes spherical harmonics (Ynm, of degree m and order n) and under various physical assumptions results in a time-dependent ODE of the perturbed interface amplitudes (one at the vapor/liquid A interface and the other at the liquid A/liquid B interface). The perturbation amplitudes are found to grow exponentially and do not depend on m. Supported by KAUST Baseline Research Funds.

76 FR 29333 - Pipeline Safety: Meetings of the Technical Pipeline Safety Standards Committee and the Technical...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-20

... DEPARTMENT OF TRANSPORTATION Pipeline and Hazardous Materials Safety Administration [Docket No... Technical Hazardous Liquid Pipeline Safety Standards Committee AGENCY: Pipeline and Hazardous Materials... for natural gas pipelines and for hazardous liquid pipelines. Both committees were established under...

Literature Review: Crud Formation at the Liquid/Liquid Interface of TBP-Based Solvent-Extraction Processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Delegard, Calvin H.; Casella, Amanda J.

2016-09-30

This report summarizes the literature reviewed on crud formation at the liquid:liquid interface of solvent extraction processes. The review is focused both on classic PUREX extraction for industrial reprocessing, especially as practiced at the Hanford Site, and for those steps specific to plutonium purification that were used at the Plutonium Reclamation Facility (PRF) within the Plutonium Finishing Plant (PFP) at the Hanford Site.

Redox chemistry at liquid/liquid interfaces

NASA Technical Reports Server (NTRS)

Volkov, A. G.; Deamer, D. W.

1997-01-01

The interface between two immiscible liquids with immobilized photosynthetic pigments can serve as the simplest model of a biological membrane convenient for the investigation of photoprocesses accompanied by spatial separation of charges. As it follows from thermodynamics, if the resolvation energies of substrates and products are very different, the interface between two immiscible liquids may act as a catalyst. Theoretical aspects of charge transfer reactions at oil/water interfaces are discussed. Conditions under which the free energy of activation of the interfacial reaction of electron transfer decreases are established. The activation energy of electron transfer depends on the charges of the reactants and dielectric permittivity of the non-aqueous phase. This can be useful when choosing a pair of immiscible solvents to decrease the activation energy of the reaction in question or to inhibit an undesired process. Experimental interfacial catalytic systems are discussed. Amphiphilic molecules such as chlorophyll or porphyrins were studied as catalysts of electron transfer reactions at the oil/water interface.

Analysis of electron transfer processes across liquid/liquid interfaces: estimation of free energy of activation using diffuse boundary model.

PubMed

Harinipriya, S; Sangaranarayanan, M V

2006-01-31

The evaluation of the free energy of activation pertaining to the electron-transfer reactions occurring at liquid/liquid interfaces is carried out employing a diffuse boundary model. The interfacial solvation numbers are estimated using a lattice gas model under the quasichemical approximation. The standard reduction potentials of the redox couples, appropriate inner potential differences, dielectric permittivities, as well as the width of the interface are included in the analysis. The methodology is applied to the reaction between [Fe(CN)6](3-/4-) and [Lu(biphthalocyanine)](3+/4+) at water/1,2-dichloroethane interface. The rate-determining step is inferred from the estimated free energy of activation for the constituent processes. The results indicate that the solvent shielding effect and the desolvation of the reactants at the interface play a central role in dictating the free energy of activation. The heterogeneous electron-transfer rate constant is evaluated from the molar reaction volume and the frequency factor.

Nonequilibrium Thermodynamics of Hydrate Growth on a Gas-Liquid Interface.

PubMed

Fu, Xiaojing; Cueto-Felgueroso, Luis; Juanes, Ruben

2018-04-06

We develop a continuum-scale phase-field model to study gas-liquid-hydrate systems far from thermodynamic equilibrium. We design a Gibbs free energy functional for methane-water mixtures that recovers the isobaric temperature-composition phase diagram under thermodynamic equilibrium conditions. The proposed free energy is incorporated into a phase-field model to study the dynamics of hydrate formation on a gas-liquid interface. We elucidate the role of initial aqueous concentration in determining the direction of hydrate growth at the interface, in agreement with experimental observations. Our model also reveals two stages of hydrate growth at an interface-controlled by a crossover in how methane is supplied from the gas and liquid phases-which could explain the persistence of gas conduits in hydrate-bearing sediments and other nonequilibrium phenomena commonly observed in natural methane hydrate systems.

Active learning in optics and photonics: Liquid Crystal Display in the do-it-yourself

NASA Astrophysics Data System (ADS)

Vauderwange, Oliver; Haiss, Ulrich; Wozniak, Peter; Israel, Kai; Curticapean, Dan

2015-10-01

Monitors are in the center of media productions and hold an important function as the main visual interface. Tablets and smartphones are becoming more and more important work tools in the media industry. As an extension to our lecture contents an intensive discussion of different display technologies and its applications is taking place now. The established LCD (Liquid Crystal Display) technology and the promising OLED (Organic Light Emitting Diode) technology are in the focus. The classic LCD is currently the most important display technology. The paper will present how the students should develop sense for display technologies besides the theoretical scientific basics. The workshop focuses increasingly on the technical aspects of the display technology and has the goal of deepening the students understanding of the functionality by building simple Liquid Crystal Displays by themselves. The authors will present their experience in the field of display technologies. A mixture of theoretical and practical lectures has the goal of a deeper understanding in the field of digital color representation and display technologies. The design and development of a suitable learning environment with the required infrastructure is crucial. The main focus of this paper is on the hands-on optics workshop "Liquid Crystal Display in the do-it-yourself".

A dose-controlled system for air-liquid interface cell exposure and application to zinc oxide nanoparticles

PubMed Central

2009-01-01

Background Engineered nanoparticles are becoming increasingly ubiquitous and their toxicological effects on human health, as well as on the ecosystem, have become a concern. Since initial contact with nanoparticles occurs at the epithelium in the lungs (or skin, or eyes), in vitro cell studies with nanoparticles require dose-controlled systems for delivery of nanoparticles to epithelial cells cultured at the air-liquid interface. Results A novel air-liquid interface cell exposure system (ALICE) for nanoparticles in liquids is presented and validated. The ALICE generates a dense cloud of droplets with a vibrating membrane nebulizer and utilizes combined cloud settling and single particle sedimentation for fast (~10 min; entire exposure), repeatable (<12%), low-stress and efficient delivery of nanoparticles, or dissolved substances, to cells cultured at the air-liquid interface. Validation with various types of nanoparticles (Au, ZnO and carbon black nanoparticles) and solutes (such as NaCl) showed that the ALICE provided spatially uniform deposition (<1.6% variability) and had no adverse effect on the viability of a widely used alveolar human epithelial-like cell line (A549). The cell deposited dose can be controlled with a quartz crystal microbalance (QCM) over a dynamic range of at least 0.02-200 μg/cm2. The cell-specific deposition efficiency is currently limited to 0.072 (7.2% for two commercially available 6-er transwell plates), but a deposition efficiency of up to 0.57 (57%) is possible for better cell coverage of the exposure chamber. Dose-response measurements with ZnO nanoparticles (0.3-8.5 μg/cm2) showed significant differences in mRNA expression of pro-inflammatory (IL-8) and oxidative stress (HO-1) markers when comparing submerged and air-liquid interface exposures. Both exposure methods showed no cellular response below 1 μg/cm2 ZnO, which indicates that ZnO nanoparticles are not toxic at occupationally allowed exposure levels. Conclusion The ALICE is a useful tool for dose-controlled nanoparticle (or solute) exposure of cells at the air-liquid interface. Significant differences between cellular response after ZnO nanoparticle exposure under submerged and air-liquid interface conditions suggest that pharmaceutical and toxicological studies with inhaled (nano-)particles should be performed under the more realistic air-liquid interface, rather than submerged cell conditions. PMID:20015351

Surface characterization of imidazolium-based ionic liquids with cyano-functionalized anions at the gas-liquid interface using sum frequency generation spectroscopy.

PubMed

Peñalber, Chariz Y; Grenoble, Zlata; Baker, Gary A; Baldelli, Steven

2012-04-21

Advancement in the field of ionic liquid technology requires a comprehensive understanding of their surface properties, as a wide range of chemical reactions occur mainly at interfaces. As essential media currently used in several technological applications, their accurate molecular level description at the gas-liquid interface is of utmost importance. Due to the high degree of chemical information provided in the vibrational spectrum, vibrational spectroscopy gives the most detailed model for molecular structure. The inherently surface-sensitive technique, sum frequency generation (SFG) spectroscopy, in combination with bulk-sensitive vibrational spectroscopic techniques such as FTIR and Raman, has been used in this report to characterize the surface of cyano-containing ionic liquids, such as [BMIM][SCN], [BMIM][DCA], [BMIM][TCM] and [EMIM][TCB] at the gas-liquid interface. By structural variation of the anion while keeping the cation constant, emphasis on the molecular arrangement of the anion at the gas-liquid interface is reported, and its subsequent role (if any) in determining the surface molecular orientation of the cation. Vibrational modes seen in the C-H stretching region revealed the presence of the cation at the gas-liquid interface. The cation orientation is independent of the type of cyano-containing anion, however, a similar arrangement at the surface as reported in previous studies was found, with the imidazolium ring lying flat at the surface, and the alkyl chains pointing towards the gas phase. SFG results show that all three anions of varying symmetry, namely, [DCA](-) (C(2v)), [TCM](-)(D(3h)) and [TCB](-) (T(d)) in ionic liquids [BMIM]DCA], [BMIM][TCM] and [EMIM][TCB] are significantly tilted from the surface plane, while the linear [SCN](-) in [BMIM][SCN] exhibited poor ordering, as seen in the absence of its C-N stretching mode in the SFG vibrational spectra. This journal is © the Owner Societies 2012

An Open Port Sampling Interface for Liquid Introduction Atmospheric Pressure Ionization Mass Spectrometry

DOE PAGES

Van Berkel, Gary J.; Kertesz, Vilmos

2015-08-25

RATIONALE: A simple method to introduce unprocessed samples into a solvent for rapid characterization by liquid introduction atmospheric pressure ionization mass spectrometry has been lacking. The continuous flow, self-cleaning open port sampling interface introduced here fills this void. METHODS: The open port sampling interface used a vertically aligned, co-axial tube arrangement enabling solvent delivery to the sampling end of the device through the tubing annulus and solvent aspiration down the center tube and into the mass spectrometer ionization source via the commercial APCI emitter probe. The solvent delivery rate to the interface was set to exceed the aspiration rate creatingmore » a continuous sampling interface along with a constant, self-cleaning spillover of solvent from the top of the probe. RESULTS: Using the open port sampling interface with positive ion mode APCI and a hybrid quadrupole time of flight mass spectrometer, rapid, direct sampling and analysis possibilities are exemplified with plastics, ballpoint and felt tip ink pens, skin, and vegetable oils. These results demonstrated that the open port sampling interface could be used as a simple, versatile and self-cleaning system to rapidly introduce multiple types of unprocessed, sometimes highly concentrated and complex, samples into a solvent flow stream for subsequent ionization and analysis by mass spectrometry. The basic setup presented here could be incorporated with any self-aspirating liquid introduction ionization source (e.g., ESI, APCI, APPI, ICP, etc.) or any type of atmospheric pressure sampling ready mass spectrometer system. CONCLUSIONS: The open port sampling interface provides a means to introduce and quickly analyze unprocessed solid or liquid samples with liquid introduction atmospheric pressure ionization source without fear of sampling interface or ionization source contamination.« less

Snap-in of particles at curved liquid interfaces

NASA Astrophysics Data System (ADS)

Li, Chao; Moradiafrapoli, Momene; Marston, Jeremy

2016-11-01

The contact of particles with liquid interfaces constitutes the first stage in the formation of a particle-laden interface, the so-called "snap-in effect". Here, we report on an experimental study using high-speed video to directly visualize the snap-in process and the approach to the equilibrium state of a particle at a curved liquid interface (i.e. droplet surface). We image the evolution of the contact line, which is found to follow a power-law scaling in time, and the dynamic contact angle during the snap-in. Both hydrophilic and hydrophobic particles are explored and we match the lift-off stage of the particles with a simple force balance. We also explore some multi-particle experiments, eluding to the dynamics of particle-laden interface formation.

Study on Orbital Liquid Transport and Interface Behavior in Vane Tank

NASA Astrophysics Data System (ADS)

Kang, Qi; Rui, Wei

2016-07-01

Liquid propellant tank is used to supply gas free liquid for spacecraft as an important part of propulsion system. The liquid behavior dominated by surface tension in microgravity is obviously different with that on the ground, which put forward a new challenge to the liquid transport and relocation. The experiments which are investigated at drop tower in National Microgravity Lab have concentrated on liquid relocation following thruster firing. Considered that the liquid located at the bottom in the direction of the acceleration vector, a sphere scale vane tank is used to study the liquid-gas interface behaviors with different acceleration vector and different filling independently and we obtain a series of stable equilibrium interface and relocation time. We find that there is an obvious sedimentation in the direction of acceleration vector when fill rate greater than 2% fill. Suggestions have been put forward that outer vanes transferring liquid to the outlet should be fixed and small holes should be dogged at the vane close to the center post to improve the liquid flow between different vanes when B0 is greater than 2.5. The research about liquid transport alone ribbon vanes is simulated though software Flow3D. The simulation process is verified by comparing the liquid lip and vapor-liquid interface obtained from drop tower experiment and simulation result when fill rate is 15%. Then the influence of fill rate, numbers of vanes and the gap between vane and wall is studied through the same simulate process. Vanes' configurations are also changed to study the effect on the lip and liquid volume below some section. Some suggestions are put forward for the design of vanes.

Ionic Liquids with Symmetric Diether Tails: Bulk and Vacuum-Liquid Interfacial Structures.

PubMed

Hettige, Jeevapani J; Amith, Weththasinghage D; Castner, Edward W; Margulis, Claudio J

2017-01-12

The behavior in the bulk and at interfaces of biphilic ionic liquids in which either the cation or anion possesses moderately long alkyl tails is to a significant degree well understood. Less clear is what happens when both the cation and anion possess tails that are not apolar, such as in the case of ether functionalities. The current article discusses the structural characteristics of C2OC2OC2-mim + /C2OC2OC2-OSO 3 - in the bulk and at the vacuum interface. We find that the vacuum interface affects only the nanometer length scale. This is in contrast to what we have recently found in ( J. Phys. Chem. Lett. , 2016 , 7 ( 19 ), 3785 - -3790 ) for isoelectronic C[8]-mim + /C[8]-OSO 3 - , where the interface effect is long ranged. Interestingly, ions with the diether tail functionality still favor the tail-outward orientation at the vacuum interface and the bulk phase preserves the alternation between charged networks and tails that is commonly observed for biphilic ionic liquids. However, such alternation is less well-defined and results in a significantly diminished first sharp diffraction peak in the bulk liquid structure function.

Investigating buried polymer interfaces using sum frequency generation vibrational spectroscopy

PubMed Central

Chen, Zhan

2010-01-01

This paper reviews recent progress in the studies of buried polymer interfaces using sum frequency generation (SFG) vibrational spectroscopy. Both buried solid/liquid and solid/solid interfaces involving polymeric materials are discussed. SFG studies of polymer/water interfaces show that different polymers exhibit varied surface restructuring behavior in water, indicating the importance of probing polymer/water interfaces in situ. SFG has also been applied to the investigation of interfaces between polymers and other liquids. It has been found that molecular interactions at such polymer/liquid interfaces dictate interfacial polymer structures. The molecular structures of silane molecules, which are widely used as adhesion promoters, have been investigated using SFG at buried polymer/silane and polymer/polymer interfaces, providing molecular-level understanding of polymer adhesion promotion. The molecular structures of polymer/solid interfaces have been examined using SFG with several different experimental geometries. These results have provided molecular-level information about polymer friction, adhesion, interfacial chemical reactions, interfacial electronic properties, and the structure of layer-by-layer deposited polymers. Such research has demonstrated that SFG is a powerful tool to probe buried interfaces involving polymeric materials, which are difficult to study by conventional surface sensitive analytical techniques. PMID:21113334

Liquid belt radiator design study

NASA Technical Reports Server (NTRS)

Teagan, W. P.; Fitzgerald, K. F.

1986-01-01

The Liquid Belt Radiator (LBR) is an advanced concept developed to meet the needs of anticipated future space missions. A previous study documented the advantages of this concept as a lightweight, easily deployable alternative to present day space heat rejection systems. The technical efforts associated with this study concentrate on refining the concept of the LBR as well as examining the issues of belt dynamics and potential application of the LBR to intermediate and high temperature heat rejection applications. A low temperature point design developed in previous work is updated assuming the use of diffusion pump oil, Santovac-6, as the heat transfer media. Additional analytical and design effort is directed toward determining the impact of interface heat exchanger, fluid bath sealing, and belt drive mechanism designs on system performance and mass. The updated design supports the earlier result by indicating a significant reduction in system specific system mass as compared to heat pipe or pumped fluid radiator concepts currently under consideration (1.3 kg/sq m versus 5 kg/sq m).

Generation and characterization of surface layers on acoustically levitated drops.

PubMed

Tuckermann, Rudolf; Bauerecker, Sigurd; Cammenga, Heiko K

2007-06-15

Surface layers of natural and technical amphiphiles, e.g., octadecanol, stearic acid and related compounds as well as perfluorinated fatty alcohols (PFA), have been investigated on the surface of acoustically levitated drops. In contrast to Langmuir troughs, traditionally used in the research of surface layers at the air-water interface, acoustic levitation offers the advantages of a minimized and contact-less technique. Although the film pressure cannot be directly adjusted on acoustically levitated drops, it runs through a wide pressure range due to the shrinking surface of an evaporating drop. During this process, different states of the generated surface layer have been identified, in particular the phase transition from the gaseous or liquid-expanded to the liquid-condensed state of surface layers of octadecanol and other related amphiphiles. Characteristic parameters, such as the relative permeation resistance and the area per molecule in a condensed surface layer, have been quantified and were found comparable to results obtained from surface layers generated on Langmuir troughs.

Long-wavelength Instability in Surface-tension-driven Bénard Convection

NASA Astrophysics Data System (ADS)

van Hook, Stephen J.

1997-03-01

Laboratory experiments and numerical simulations reveal that a liquid layer heated from below and possessing a free upper surface can undergo a long-wavelength deformational instability that causes rupture of the interface.(S. J. VanHook, M. F. Schatz, W. D. McCormick, J. B. Swift, and H. L. Swinney, Phys. Rev. Lett.) 75, 4397 (1995). Depending on the depth and thermal conductivity of the liquid and the overlying gas layer, the interface can rupture downwards and form a dry spot or rupture upwards and form a high spot. This long-wavelength instability competes with the formation of Bénard hexagons for thin or viscous liquid layers, or for liquid layers in microgravity.

Water-mediated ion-ion interactions are enhanced at the water vapor-liquid interface.

PubMed

Venkateshwaran, Vasudevan; Vembanur, Srivathsan; Garde, Shekhar

2014-06-17

There is overwhelming evidence that ions are present near the vapor-liquid interface of aqueous salt solutions. Charged groups can also be driven to interfaces by attaching them to hydrophobic moieties. Despite their importance in many self-assembly phenomena, how ion-ion interactions are affected by interfaces is not understood. We use molecular simulations to show that the effective forces between small ions change character dramatically near the water vapor-liquid interface. Specifically, the water-mediated attraction between oppositely charged ions is enhanced relative to that in bulk water. Further, the repulsion between like-charged ions is weaker than that expected from a continuum dielectric description and can even become attractive as the ions are drawn to the vapor side. We show that thermodynamics of ion association are governed by a delicate balance of ion hydration, interfacial tension, and restriction of capillary fluctuations at the interface, leading to nonintuitive phenomena, such as water-mediated like charge attraction. "Sticky" electrostatic interactions may have important consequences on biomolecular structure, assembly, and aggregation at soft liquid interfaces. We demonstrate this by studying an interfacially active model peptide that changes its structure from α-helical to a hairpin-turn-like one in response to charging of its ends.

Water-mediated ion–ion interactions are enhanced at the water vapor–liquid interface

PubMed Central

Venkateshwaran, Vasudevan; Vembanur, Srivathsan; Garde, Shekhar

2014-01-01

There is overwhelming evidence that ions are present near the vapor–liquid interface of aqueous salt solutions. Charged groups can also be driven to interfaces by attaching them to hydrophobic moieties. Despite their importance in many self-assembly phenomena, how ion–ion interactions are affected by interfaces is not understood. We use molecular simulations to show that the effective forces between small ions change character dramatically near the water vapor–liquid interface. Specifically, the water-mediated attraction between oppositely charged ions is enhanced relative to that in bulk water. Further, the repulsion between like-charged ions is weaker than that expected from a continuum dielectric description and can even become attractive as the ions are drawn to the vapor side. We show that thermodynamics of ion association are governed by a delicate balance of ion hydration, interfacial tension, and restriction of capillary fluctuations at the interface, leading to nonintuitive phenomena, such as water-mediated like charge attraction. “Sticky” electrostatic interactions may have important consequences on biomolecular structure, assembly, and aggregation at soft liquid interfaces. We demonstrate this by studying an interfacially active model peptide that changes its structure from α-helical to a hairpin-turn–like one in response to charging of its ends. PMID:24889634

KENNEDY SPACE CENTER, FLA. - Workers in the Orbiter Processing Facility insert the liquid oxygen feedline for the 17-inch disconnect in the orbiter Discovery. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

NASA Image and Video Library

2003-11-11

KENNEDY SPACE CENTER, FLA. - Workers in the Orbiter Processing Facility insert the liquid oxygen feedline for the 17-inch disconnect in the orbiter Discovery. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers install the liquid oxygen feedline for the 17-inch disconnect on orbiter Discovery. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

NASA Image and Video Library

2003-11-11

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers install the liquid oxygen feedline for the 17-inch disconnect on orbiter Discovery. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers raise the liquid oxygen feedline for the 17-inch disconnect toward orbiter Discovery for installation. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

NASA Image and Video Library

2003-11-11

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers raise the liquid oxygen feedline for the 17-inch disconnect toward orbiter Discovery for installation. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers lift the liquid oxygen feedline for the 17-inch disconnect toward orbiter Discovery for installation. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

NASA Image and Video Library

2003-11-11

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers lift the liquid oxygen feedline for the 17-inch disconnect toward orbiter Discovery for installation. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers move the liquid oxygen feedline for the 17-inch disconnect toward orbiter Discovery for installation. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

NASA Image and Video Library

2003-11-11

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers move the liquid oxygen feedline for the 17-inch disconnect toward orbiter Discovery for installation. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

Redox Electrocatalysis of Floating Nanoparticles: Determining Electrocatalytic Properties without the Influence of Solid Supports.

PubMed

Peljo, Pekka; Scanlon, Micheál D; Olaya, Astrid J; Rivier, Lucie; Smirnov, Evgeny; Girault, Hubert H

2017-08-03

Redox electrocatalysis (catalysis of electron-transfer reactions by floating conductive particles) is discussed from the point-of-view of Fermi level equilibration, and an overall theoretical framework is given. Examples of redox electrocatalysis in solution, in bipolar configuration, and at liquid-liquid interfaces are provided, highlighting that bipolar and liquid-liquid interfacial systems allow the study of the electrocatalytic properties of particles without effects from the support, but only liquid-liquid interfaces allow measurement of the electrocatalytic current directly. Additionally, photoinduced redox electrocatalysis will be of interest, for example, to achieve water splitting.

Waterflooding injectate design systems and methods

DOEpatents

Brady, Patrick V.; Krumhansl, James L.

2014-08-19

A method of designing an injectate to be used in a waterflooding operation is disclosed. One aspect includes specifying data representative of chemical characteristics of a liquid hydrocarbon, a connate, and a reservoir rock, of a subterranean reservoir. Charged species at an interface of the liquid hydrocarbon are determined based on the specified data by evaluating at least one chemical reaction. Charged species at an interface of the reservoir rock are determined based on the specified data by evaluating at least one chemical reaction. An extent of surface complexation between the charged species at the interfaces of the liquid hydrocarbon and the reservoir rock is determined by evaluating at least one surface complexation reaction. The injectate is designed and is operable to decrease the extent of surface complexation between the charged species at interfaces of the liquid hydrocarbon and the reservoir rock. Other methods, apparatus, and systems are disclosed.

Numerical Simulation of Polysilicon Solid-liquid Interface Transmogrification in Heat Transfer Process

NASA Astrophysics Data System (ADS)

Yang, Xi; Ma, Wenhui; Lv, Guoqiang; Zhang, Mingyu

2018-01-01

The shape of solid-liquid interface during the directional solidification process, which is difficult to be observed and measured in actual processes, controls the grain orientation and grain size of polysilicon ingot. We carried out numerical calculations of the directional solidification progress of polycrystalline silicon and invested the means to deal with the latent heat of solidification in numerical simulation. The distributions of the temperature field of the melt for the crystallization progress as well as the transformation of the solid-liquid interface were obtained. The simulation results are consistent with the experimental outcomes. The results show that the curvature of solid-liquid interface is small and stability, larger grain sized columnar crystal can be grown in the laboratory-scale furnace at a solidification rate of 10 μm•s-1. It shall provide important theoretical basis for metallurgical process and polysilicon production technology.

Influence of volume ratio of liquid to solid and low pouring temperature on interface structure of cast Babbitt-steel bimetal composite

NASA Astrophysics Data System (ADS)

Fathy, Naglaa; Ramadan, Mohamed

2018-05-01

The influence of volume ratio of liquid to Solid and low pouring temperature on interface structure of cast Babbitt-steel bimetal composite was evaluated for static casting technique. At low pouring temperature of 380 °C, Babbitt microstructures are improved to be finer and more globular. On the other side pouring the Babbitt at low pouring temperature of 380 °C increases the chance of present higher unbonded area percent. Increasing the volume ratio of liquid to solid decreases the Sn-Pb interface thicknesses and increases the bonded interface area. In order to optimize the production of Babbitt-steel bimetal composite at low pouring temperature, the volume ratio of liquid Babbitt to solid steel shell should be higher value that could be more than 5 depending on the extrapolation of current data presented.

Ionic structure in liquids confined by dielectric interfaces

NASA Astrophysics Data System (ADS)

Jing, Yufei; Jadhao, Vikram; Zwanikken, Jos W.; Olvera de la Cruz, Monica

2015-11-01

The behavior of ions in liquids confined between macromolecules determines the outcome of many nanoscale assembly processes in synthetic and biological materials such as colloidal dispersions, emulsions, hydrogels, DNA, cell membranes, and proteins. Theoretically, the macromolecule-liquid boundary is often modeled as a dielectric interface and an important quantity of interest is the ionic structure in a liquid confined between two such interfaces. The knowledge gleaned from the study of ionic structure in such models can be useful in several industrial applications, such as in the design of double-layer supercapacitors for energy storage and in the extraction of metal ions from wastewater. In this article, we compute the ionic structure in a model system of electrolyte confined by two planar dielectric interfaces using molecular dynamics simulations and liquid state theory. We explore the effects of high electrolyte concentrations, multivalent ions, dielectric contrasts, and external electric field on the ionic distributions. We observe the presence of non-monotonic ionic density profiles leading to a layered structure in the fluid which is attributed to the competition between electrostatic and steric (entropic) interactions. We find that thermal forces that arise from symmetry breaking at the interfaces can have a profound effect on the ionic structure and can oftentimes overwhelm the influence of the dielectric discontinuity. The combined effect of ionic correlations and inhomogeneous dielectric permittivity significantly changes the character of the effective interaction between the two interfaces.

Noncovalent Pi-Pi Stacking at the Carbon-Electrolyte Interface: Controlling the Voltage Window of Electrochemical Supercapacitors.

PubMed

Li, Mengya; Westover, Andrew S; Carter, Rachel; Oakes, Landon; Muralidharan, Nitin; Boire, Timothy C; Sung, Hak-Joon; Pint, Cary L

2016-08-03

A key parameter in the operation of an electrochemical double-layer capacitor is the voltage window, which dictates the device energy density and power density. Here we demonstrate experimental evidence that π-π stacking at a carbon-ionic liquid interface can modify the operation voltage of a supercapacitor device by up to 30%, and this can be recovered by steric hindrance at the electrode-electrolyte interface introduced by poly(ethylene oxide) polymer electrolyte additives. This observation is supported by Raman spectroscopy, electrochemical impedance spectroscopy, and differential scanning calorimetry that each independently elucidates the signature of π-π stacking between imidazole groups in the ionic liquid and the carbon surface and the role this plays to lower the energy barrier for charge transfer at the electrode-electrolyte interface. This effect is further observed universally across two separate ionic liquid electrolyte systems and is validated by control experiments showing an invariant electrochemical window in the absence of a carbon-ionic liquid electrode-electrolyte interface. As interfacial or noncovalent interactions are usually neglected in the mechanistic picture of double-layer capacitors, this work highlights the importance of understanding chemical properties at supercapacitor interfaces to engineer voltage and energy capability.

Optical fingerprints of solid-liquid interfaces: a joint ATR-IR and first principles investigation

NASA Astrophysics Data System (ADS)

Yang, L.; Niu, F.; Tecklenburg, S.; Pander, M.; Nayak, S.; Erbe, A.; Wippermann, S.; Gygi, F.; Galli, G.

Despite the importance of understanding the structural and bonding properties of solid-liquid interfaces for a wide range of (photo-)electrochemical applications, there are presently no experimental techniques available to directly probe the microscopic structure of solid-liquid interfaces. To develop robust strategies to interpret experiments and validate theory, we carried out attenuated total internal reflection (ATR-IR) spectroscopy measurements and ab initio molecular dynamics (AIMD) simulations of the vibrational properties of interfaces between liquid water and well-controlled prototypical semiconductor substrates. We show the Ge(100)/H2O interface to feature a reversible potential-dependent surface phase transition between Ge-H and Ge-OH termination. The Si(100)/H2O interface is proposed as a model system for corrosion and oxidation processes. We performed AIMD calculations under finite electric fields, revealing different pathways for initial oxidation. These pathways are predicted to exhibit unique spectral signatures. A significant increase in surface specificity can be achieved utilizing an angle-dependent ATR-IR experiment, which allows to detect such signatures at the interfacial layer and consequently changes in the hydrogen bond network. Funding from DOE-BES Grant No. DE-SS0008939 and the Deutsche Forschungsgemeinschaft (RESOLV, EXC 1069) are gratefully acknowledged.

Analysis of Gibbs monolayer adsorbed at the toluene/water interface by UV-visible partial internal reflection spectrometry.

PubMed

Moriya, Yoshio; Hasegawa, Takeshi; Okada, Tetsuo; Ogawa, Nobuaki; Kawai, Erika; Abe, Kosuke; Ogasawara, Masataka; Kato, Sumio; Nakata, Shinichi

2006-11-15

Gibbs monolayers of lipophilic tetraphenylporphyrinatomanganese(III) and hydrophilic diacid of meso-tetrakis(4-sulfonatopheny)porphyrin adsorbed at the liquid-liquid interface have been analyzed by UV-visible external reflection (ER) and partial internal reflection (PIR) spectra measured at different angles of incidence. The angle-dependent ER and PIR spectra over the Brewster angles (thetaERB and thetaIRB) have readily been measured at the toluene/water interface. As preliminarily expected in our previous study, the present study has first proved that the reflection-absorbance of UV-visible PIR spectra quantitatively agrees with the theoretical calculations for the Gibbs monolayer over thetaIRB. In addition, it has also been proved that the absorbance of the PIR spectra is greatly enhanced in comparison to that of the ATR spectra. The enhancement is caused by an optical effect in the monolayer sandwiched between two phases of toluene and water that have different but refractive indices close to each other. This optical enhancement requires an optically perfect contact between the phases, which is difficult to prepare for a solid-solid contact. At the liquid/liquid interface, however, an ideal optical contact is easily realized, which makes the enhancement as much as the theoretical expectation. The PIR spectrometry will be recognized to be a new high-sensitive analytical tool to study Gibbs monolayer at the liquid/liquid interface.

Specific interface area in a thin layer system of two immiscible liquids with vapour generation at the contact interface

NASA Astrophysics Data System (ADS)

Pimenova, Anastasiya V.; Gazdaliev, Ilias M.; Goldobin, Denis S.

2017-06-01

For well-stirred multiphase fluid systems the mean interface area per unit volume, or “specific interface area” SV, is a significant characteristic of the system state. In particular, it is important for the dynamics of systems of immiscible liquids experiencing interfacial boiling. We estimate the value of parameter SV as a function of the heat influx {\\dot{Q}}V to the system or the average system overheat <Θ> above the interfacial boiling point. The derived results can be reformulated for the case of an endothermic chemical reaction between two liquid reagents with the gaseous form of one of the reaction products. The final results are restricted to the case of thin layers, where the potential gravitational energy of bubbles leaving the contact interface is small compared to their surface tension energy.

Synergistic effect of dicarbollide anions in liquid-liquid extraction: a molecular dynamics study at the octanol-water interface.

PubMed

Chevrot, G; Schurhammer, R; Wipff, G

2007-04-28

We report a molecular dynamics study of chlorinated cobalt bis(dicarbollide) anions [(B(9)C(2)H(8)Cl(3))(2)Co](-)"CCD(-)" in octanol and at the octanol-water interface, with the main aim to understand why these hydrophobic species act as strong synergists in assisted liquid-liquid cation extraction. Neat octanol is quite heterogeneous and is found to display dual solvation properties, allowing to well solubilize CCD(-), Cs(+) salts in the form of diluted pairs or oligomers, without displaying aggregation. At the aqueous interface, octanol behaves as an amphiphile, forming either monolayers or bilayers, depending on the initial state and confinement conditions. In biphasic octanol-water systems, CCD(-) anions are found to mainly partition to the organic phase, thus attracting Cs(+) or even more hydrophilic counterions like Eu(3+) into that phase. The remaining CCD(-) anions adsorb at the interface, but are less surface active than at the chloroform interface. Finally, we compare the interfacial behavior of the Eu(BTP)(3)(3+) complex in the absence and in the presence of CCD(-) anions and extractant molecules. It is found that when the CCD(-)'s are concentrated enough, the complex is extracted to the octanol phase. Otherwise, it is trapped at the interface, attracted by water. These results are compared to those obtained with chloroform as organic phase and discussed in the context of synergistic effect of CCD(-) in liquid-liquid extraction, pointing to the importance of dual solvation properties of octanol and of the hydrophobic character of CCD(-) for synergistic extraction of cations.

Comparing the catalytic oxidation of ethanol at the solid-gas and solid-liquid interfaces over size-controlled Pt nanoparticles: striking differences in kinetics and mechanism.

PubMed

Sapi, Andras; Liu, Fudong; Cai, Xiaojun; Thompson, Christopher M; Wang, Hailiang; An, Kwangjin; Krier, James M; Somorjai, Gabor A

2014-11-12

Pt nanoparticles with controlled size (2, 4, and 6 nm) are synthesized and tested in ethanol oxidation by molecular oxygen at 60 °C to acetaldehyde and carbon dioxide both in the gas and liquid phases. The turnover frequency of the reaction is ∼80 times faster, and the activation energy is ∼5 times higher at the gas-solid interface compared to the liquid-solid interface. The catalytic activity is highly dependent on the size of the Pt nanoparticles; however, the selectivity is not size sensitive. Acetaldehyde is the main product in both media, while twice as much carbon dioxide was observed in the gas phase compared to the liquid phase. Added water boosts the reaction in the liquid phase; however, it acts as an inhibitor in the gas phase. The more water vapor was added, the more carbon dioxide was formed in the gas phase, while the selectivity was not affected by the concentration of the water in the liquid phase. The differences in the reaction kinetics of the solid-gas and solid-liquid interfaces can be attributed to the molecular orientation deviation of the ethanol molecules on the Pt surface in the gas and liquid phases as evidenced by sum frequency generation vibrational spectroscopy.

Thermal-hydraulic behaviors of vapor-liquid interface due to arrival of a pressure wave

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inoue, Akira; Fujii, Yoshifumi; Matsuzaki, Mitsuo

In the vapor explosion, a pressure wave (shock wave) plays a fundamental role for triggering, propagation and enhancement of the explosion. Energy of the explosion is related to the magnitude of heat transfer rate from hot liquid to cold volatile one. This is related to an increasing rate of interface area and to an amount of transient heat flux between the liquids. In this study, the characteristics of transient heat transfer and behaviors of vapor film both on the platinum tube and on the hot melt tin drop, under same boundary conditions have been investigated. It is considered that theremore » exists a fundamental mechanism of the explosion in the initial expansion process of the hot liquid drop immediately after arrival of pressure wave. The growth rate of the vapor film is much faster on the hot liquid than that on the solid surface. Two kinds of roughness were observed, one due to the Taylor instability, by rapid growth of the explosion bubble, and another, nucleation sites were observed at the vapor-liquid interface. Based on detailed observation of early stage interface behaviors after arrival of a pressure wave, the thermal fragmentation mechanism is proposed.« less

The film tells the story: Physical-chemical characteristics of IgG at the liquid-air interface.

PubMed

Koepf, Ellen; Schroeder, Rudolf; Brezesinski, Gerald; Friess, Wolfgang

2017-10-01

The presence of liquid-air interfaces in protein pharmaceuticals is known to negatively impact product stability. Nevertheless, the mechanisms behind interface-related protein aggregation are not yet fully understood. Little is known about the physical-chemical behavior of proteins adsorbed to the interface. Therefore, the combinatorial use of appropriate surface-sensitive analytical methods such as Langmuir trough experiments, Infrared Reflection-Absorption Spectroscopy (IRRAS), Brewster Angle Microscopy (BAM), and Atomic Force Microscopy (AFM) is highly expedient to uncover structures and events at the liquid-air interface directly. Concentration-dependent adsorption of a human immunoglobulin G (IgG) and characteristic surface-pressure/area isotherms substantiated the amphiphilic nature of the protein molecules as well as the formation of a compressible protein film at the liquid-air interface. Upon compression, the IgG molecules do not readily desorb but form a highly compressible interfacial film. IRRA spectra proved not only the presence of the protein at the interface, but also showed that the secondary structure does not change considerably during adsorption or compression. IRRAS experiments at different angles of incidence indicated that the film thickness and/or packing density increases upon compression. Furthermore, BAM images exposed the presence of a coherent but heterogeneous distribution of the protein at the interface. Topographical differences within the protein film after adsorption, compression and decompression were revealed using underwater AFM. The combinatorial use of physical-chemical, spectroscopic and microscopic methods provided useful insights into the liquid-air interfacial protein behavior and revealed the formation of a continuous but inhomogeneous film of native-like protein molecules whose topographical appearance is affected by compressive forces. Copyright © 2017 Elsevier B.V. All rights reserved.

Water liquid-vapor interface subjected to various electric fields: A molecular dynamics study.

PubMed

Nikzad, Mohammadreza; Azimian, Ahmad Reza; Rezaei, Majid; Nikzad, Safoora

2017-11-28

Investigation of the effects of E-fields on the liquid-vapor interface is essential for the study of floating water bridge and wetting phenomena. The present study employs the molecular dynamics method to investigate the effects of parallel and perpendicular E-fields on the water liquid-vapor interface. For this purpose, density distribution, number of hydrogen bonds, molecular orientation, and surface tension are examined to gain a better understanding of the interface structure. Results indicate enhancements in parallel E-field decrease the interface width and number of hydrogen bonds, while the opposite holds true in the case of perpendicular E-fields. Moreover, perpendicular fields disturb the water structure at the interface. Given that water molecules tend to be parallel to the interface plane, it is observed that perpendicular E-fields fail to realign water molecules in the field direction while the parallel ones easily do so. It is also shown that surface tension rises with increasing strength of parallel E-fields, while it reduces in the case of perpendicular E-fields. Enhancement of surface tension in the parallel field direction demonstrates how the floating water bridge forms between the beakers. Finally, it is found that application of external E-fields to the liquid-vapor interface does not lead to uniform changes in surface tension and that the liquid-vapor interfacial tension term in Young's equation should be calculated near the triple-line of the droplet. This is attributed to the multi-directional nature of the droplet surface, indicating that no constant value can be assigned to a droplet's surface tension in the presence of large electric fields.

Improved Management of the Technical Interfaces Between the Hanford Tank Farm Operator and the Hanford Waste Treatment Plant - 13383

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duncan, Garth M.; Saunders, Scott A.

2013-07-01

The Department of Energy (DOE) is constructing the Waste Treatment and Immobilization Plant (WTP) at the Hanford site in Washington to treat and immobilize approximately 114 million gallons of high level radioactive waste (after all retrievals are accomplished). In order for the WTP to be designed and operated successfully, close coordination between the WTP engineering, procurement, and construction contractor, Bechtel National, Inc. and the tank farms operating contractor (TOC), Washington River Protection Solutions, LLC, is necessary. To develop optimal solutions for DOE and for the treatment of the waste, it is important to deal with the fact that two differentmore » prime contractors, with somewhat differing contracts, are tasked with retrieving and delivering the waste and for treating and immobilizing that waste. The WTP and the TOC have over the years cooperated to manage the technical interface. To manage what is becoming a much more complicated interface as the WTP design progresses and new technical issues have been identified, an organizational change was made by WTP and TOC in November of 2011. This organizational change created a co-located integrated project team (IPT) to deal with mutual and interface issues. The Technical Organization within the One System IPT includes employees from both TOC and WTP. This team has worked on a variety of technical issues of mutual interest and concern. Technical issues currently being addressed include: - The waste acceptance criteria; - Waste feed delivery and the associated data quality objectives (DQO); - Evaluation of the effects of performing a riser cut on a single shell tank on WTP operations; - The disposition of secondary waste from both TOC and WTP; - The close coordination of the TOC double shell tank mixing and sampling program and the Large Scale Integrated Test (LSIT) program for pulse jet mixers at WTP along with the associated responses to the Defense Nuclear Facilities Safety Board (DNFSB) Recommendation 2010-2; - Development of a set of alternatives to the current baseline that involve aspects of direct feed, feed conditioning, and design changes. The One System Technical Organization has served WTP, TOC, and DOE well in managing and resolving issues at the interface. This paper describes the organizational structure used to improve the interface and several examples of technical interface issues that have been successfully addressed by the new organization. (authors)« less

A Study of Nucleate Boiling with Forced Convection in Microgravity

NASA Technical Reports Server (NTRS)

Merte, Herman, Jr.

1996-01-01

Boiling is a rather imprecise term applied to the process of evaporation in which the rate of liquid-vapor phase change is large. In seeking to determine the role and significance of body forces on the process, of which buoyancy or gravity is just one agent, it becomes necessary to define the term more precisely. It is generally characterized by the formation and growth of individual vapor bubbles arising from heat transfer to the liquid, either at a solid/liquid or liquid/liquid interface, or volumetrically. The terms 'bubble' boiling and 'nucleate' boiling are frequently used, in recognition of the interactions of surface tension and other forces in producing discrete bubbles at distinctive locations (although not always). Primary considerations are that evaporation can occur only at existing liquid-vapor interfaces, so that attention must be given to the formation of an interface (the nucleation process), and that the latent heat for this evaporation can come only from the superheated liquid, so that attention must also be given to the temperature distributions in the liquid.

Dynamic microscopy of nanoscale cluster growth at the solid-liquid interface.

PubMed

Williamson, M J; Tromp, R M; Vereecken, P M; Hull, R; Ross, F M

2003-08-01

Dynamic processes at the solid-liquid interface are of key importance across broad areas of science and technology. Electrochemical deposition of copper, for example, is used for metallization in integrated circuits, and a detailed understanding of nucleation, growth and coalescence is essential in optimizing the final microstructure. Our understanding of processes at the solid-vapour interface has advanced tremendously over the past decade due to the routine availability of real-time, high-resolution imaging techniques yielding data that can be compared quantitatively with theory. However, the difficulty of studying the solid-liquid interface leaves our understanding of processes there less complete. Here we analyse dynamic observations--recorded in situ using a novel transmission electron microscopy technique--of the nucleation and growth of nanoscale copper clusters during electrodeposition. We follow in real time the evolution of individual clusters, and compare their development with simulations incorporating the basic physics of electrodeposition during the early stages of growth. The experimental technique developed here is applicable to a broad range of dynamic phenomena at the solid-liquid interface.

Prenucleation Induced by Crystalline Substrates

NASA Astrophysics Data System (ADS)

Men, H.; Fan, Z.

2018-04-01

Prenucleation refers to the phenomenon of atomic ordering in the liquid adjacent to the substrate/liquid interface at temperatures above the liquidus. In this paper, we have systematically investigated and holistically quantified the prenucleation phenomenon as a function of temperature and the lattice misfit between the substrate and the solid, using molecular dynamics (MD) simulations. Our results have confirmed that at temperatures above the liquidus, the atoms in the liquid at the interface may exhibit pronounced atomic ordering, manifested by atomic layering normal to the interface, in-plane atomic ordering parallel to the interface, and the formation of a 2-dimensional (2D) ordered structure (a few atomic layers in thickness) on the substrate surface. Holistic quantification of such atomic ordering at the interface has revealed that the atomic layering is independent of lattice misfit and is only slightly enhanced by reducing temperature while both in-plane atomic ordering and the formation of the 2D ordered structure are significantly enhanced by reducing the lattice misfit and/or temperature. This substrate-induced atomic ordering in the liquid may have a significant influence on the subsequent heterogeneous nucleation process.

Dynamic equilibrium under vibrations of H2 liquid-vapor interface at various gravity levels

NASA Astrophysics Data System (ADS)

Gandikota, G.; Chatain, D.; Lyubimova, T.; Beysens, D.

2014-06-01

Horizontal vibration applied to the support of a simple pendulum can deviate from the equilibrium position of the pendulum to a nonvertical position. A similar phenomenon is expected when a liquid-vapor interface is subjected to strong horizontal vibration. Beyond a threshold value of vibrational velocity the interface should attain an equilibrium position at an angle to the initial horizontal position. In the present paper experimental investigation of this phenomenon is carried out in a magnetic levitation device to study the effect of the vibration parameters, gravity acceleration, and the liquid-vapor density on the interface position. The results compare well with the theoretical expression derived by Wolf [G. H. Wolf, Z. Phys. B 227, 291 (1969), 10.1007/BF01397662].

First-principles quantum-mechanical investigations of biomass conversion at the liquid-solid interfaces

NASA Astrophysics Data System (ADS)

Dang, Hongli; Xue, Wenhua; Liu, Yingdi; Jentoft, Friederike; Resasco, Daniel; Wang, Sanwu

2014-03-01

We report first-principles density-functional calculations and ab initio molecular dynamics (MD) simulations for the reactions involving furfural, which is an important intermediate in biomass conversion, at the catalytic liquid-solid interfaces. The different dynamic processes of furfural at the water-Cu(111) and water-Pd(111) interfaces suggest different catalytic reaction mechanisms for the conversion of furfural. Simulations for the dynamic processes with and without hydrogen demonstrate the importance of the liquid-solid interface as well as the presence of hydrogen in possible catalytic reactions including hydrogenation and decarbonylation of furfural. Supported by DOE (DE-SC0004600). This research used the supercomputer resources of the XSEDE, the NERSC Center, and the Tandy Supercomputing Center.

Fluid-fluid interfacial mobility from random walks

NASA Astrophysics Data System (ADS)

Barclay, Paul L.; Lukes, Jennifer R.

2017-12-01

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

In situ creation of reactive polymer nanoparticles and resulting polymer layers formed at the interfaces of liquid crystals (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kang, Shin-Woong; Kundu, Sudarshan; Park, Heung-Shik; Oh, Keun Chan; Lyu, Jae Jin

2017-02-01

We report the in situ creation of reactive polymer nanoparticles and resulting polymer networks formed at the interfaces of liquid crystals. It is known that polymerization-induced phase separation proceeds in two distinct regimes depending on the concentration of monomer. For a high monomer concentration, phase separation occurs mainly through the spinodal decomposition process, consequently resulting in interpenetrating polymer networks. For a dilute system, however, the phase separation mainly proceeds and completes in the binodal decomposition regime. The system resembles the aggregation process of colloidal particle. In this case, the reaction kinetics is limited by the reaction between in situ created polymer aggregates and hence the network morphologies are greatly influenced by the diffusion of reactive polymer particles. The thin polymer layers localized at the surface of substrate are inevitably observed and can be comprehended by the interfacial adsorption and further cross-linking reaction of reactive polymer aggregates at the interface. This process provides a direct perception on understanding polymer stabilized liquid crystals accomplished by the interfacial polymer layer. The detailed study has been performed for an extremely dilute condition (below 0.5 wt%) by employing systematic experimental approaches. Creation and growth of polymer nanoparticles have been measured by particle size analyzer. The interfacial localization of polymer aggregates and resulting interfacial layer formation with a tens of nanometer scale have been exploited at various interfaces such as liquid-solid, liquid-liquid, and liquid-gas interfaces. The resulting interfacial layers have been characterized by using fuorescent confocal microscope and field emission scanning electron microscope. The detailed processes of the polymer stabilized vertically aligned liquid crystals will be discussed in support of the reported study.

Simultaneous probing of bulk liquid phase and catalytic gas-liquid-solid interface under working conditions using attenuated total reflection infrared spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meemken, Fabian; Müller, Philipp; Hungerbühler, Konrad

Design and performance of a reactor set-up for attenuated total reflection infrared (ATR-IR) spectroscopy suitable for simultaneous reaction monitoring of bulk liquid and catalytic solid-liquid-gas interfaces under working conditions are presented. As advancement of in situ spectroscopy an operando methodology for gas-liquid-solid reaction monitoring was developed that simultaneously combines catalytic activity and molecular level detection at the catalytically active site of the same sample. Semi-batch reactor conditions are achieved with the analytical set-up by implementing the ATR-IR flow-through cell in a recycle reactor system and integrating a specifically designed gas feeding system coupled with a bubble trap. By the usemore » of only one spectrometer the design of the new ATR-IR reactor cell allows for simultaneous detection of the bulk liquid and the catalytic interface during the working reaction. Holding two internal reflection elements (IRE) the sample compartments of the horizontally movable cell are consecutively flushed with reaction solution and pneumatically actuated, rapid switching of the cell (<1 s) enables to quasi simultaneously follow the heterogeneously catalysed reaction at the catalytic interface on a catalyst-coated IRE and in the bulk liquid on a blank IRE. For a complex heterogeneous reaction, the asymmetric hydrogenation of 2,2,2-trifluoroacetophenone on chirally modified Pt catalyst the elucidation of catalytic activity/enantioselectivity coupled with simultaneous monitoring of the catalytic solid-liquid-gas interface is shown. Both catalytic activity and enantioselectivity are strongly dependent on the experimental conditions. The opportunity to gain improved understanding by coupling measurements of catalytic performance and spectroscopic detection is presented. In addition, the applicability of modulation excitation spectroscopy and phase-sensitive detection are demonstrated.« less

Nanoscale structure of the oil-water interface

DOE PAGES

Fukuto, M.; Ocko, B. M.; Bonthuis, D. J.; ...

2016-12-15

X-ray reflectivity (XR) and atomistic molecular dynamics (MD) simulations, carried out to determine the structure of the oil-water interface, provide new insight into the simplest liquid-liquid interface. For several oils (hexane, dodecane, and hexadecane) the XR shows very good agreement with a monotonic interface-normal electron density profile (EDP) broadened only by capillary waves. Similar agreement is also found for an EDP including a sub-Å thick electron depletion layer separating the oil and the water. As a result, the XR and MD derived depletions are much smaller than reported for the interface between solid-supported hydrophobic monolayers and water.

Comparison study on the calculation formula of evaporation mass flux through the plane vapour-liquid interface

NASA Astrophysics Data System (ADS)

Zhang, L.; Li, Y. R.; Zhou, L. Q.; Wu, C. M.

2017-11-01

In order to understand the influence of various factors on the evaporation rate on the vapor-liquid interface, the evaporation process of water in pure steam environment was calculated based on the statistical rate theory (SRT), and the results were compared with those from the traditional Hertz-Knudsen equation. It is found that the evaporation rate on the vapor-liquid interface increases with the increase of evaporation temperature and evaporation temperature difference and the decrease of vapor pressure. When the steam is in a superheated state, even if the temperature of the liquid phase is lower than that of the vapor phase, the evaporation may also occur on the vapor-liquid interface; at this time, the absolute value of the critical temperature difference for occurring evaporation decreases with the increase of vapor pressure. When the evaporation temperature difference is smaller, the theoretical calculation results based on the SRT are basically the same as the predicated results from the Hertz-Knudsen equation; but the deviation between them increases with the increase of temperature difference.

Pressurization of a Flightweight, Liquid Hydrogen Tank: Evaporation and Condensation at a Liquid Vapor Interface

NASA Technical Reports Server (NTRS)

Stewart, Mark E.

2017-01-01

Evaporation and condensation at a liquidvapor interface is important for long-term, in-space cryogenic propellant storage. Yet the current understanding of interfacial physics does not predict behavior or evaporation condensation rates. The proposed paper will present a physical model, based on the 1-D Heat equation and Schrages equation which demonstrates thin thermal layers at the fluidvapor interface.

The ensemble switch method for computing interfacial tensions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmitz, Fabian; Virnau, Peter

2015-04-14

We present a systematic thermodynamic integration approach to compute interfacial tensions for solid-liquid interfaces, which is based on the ensemble switch method. Applying Monte Carlo simulations and finite-size scaling techniques, we obtain results for hard spheres, which are in agreement with previous computations. The case of solid-liquid interfaces in a variant of the effective Asakura-Oosawa model and of liquid-vapor interfaces in the Lennard-Jones model are discussed as well. We demonstrate that a thorough finite-size analysis of the simulation data is required to obtain precise results for the interfacial tension.

A new method for ultrasound detection of interfacial position in gas-liquid two-phase flow.

PubMed

Coutinho, Fábio Rizental; Ofuchi, César Yutaka; de Arruda, Lúcia Valéria Ramos; Neves, Flávio; Morales, Rigoberto E M

2014-05-22

Ultrasonic measurement techniques for velocity estimation are currently widely used in fluid flow studies and applications. An accurate determination of interfacial position in gas-liquid two-phase flows is still an open problem. The quality of this information directly reflects on the accuracy of void fraction measurement, and it provides a means of discriminating velocity information of both phases. The algorithm known as Velocity Matched Spectrum (VM Spectrum) is a velocity estimator that stands out from other methods by returning a spectrum of velocities for each interrogated volume sample. Interface detection of free-rising bubbles in quiescent liquid presents some difficulties for interface detection due to abrupt changes in interface inclination. In this work a method based on velocity spectrum curve shape is used to generate a spatial-temporal mapping, which, after spatial filtering, yields an accurate contour of the air-water interface. It is shown that the proposed technique yields a RMS error between 1.71 and 3.39 and a probability of detection failure and false detection between 0.89% and 11.9% in determining the spatial-temporal gas-liquid interface position in the flow of free rising bubbles in stagnant liquid. This result is valid for both free path and with transducer emitting through a metallic plate or a Plexiglas pipe.

A New Method for Ultrasound Detection of Interfacial Position in Gas-Liquid Two-Phase Flow

PubMed Central

Coutinho, Fábio Rizental; Ofuchi, César Yutaka; de Arruda, Lúcia Valéria Ramos; Jr., Flávio Neves; Morales, Rigoberto E. M.

2014-01-01

Ultrasonic measurement techniques for velocity estimation are currently widely used in fluid flow studies and applications. An accurate determination of interfacial position in gas-liquid two-phase flows is still an open problem. The quality of this information directly reflects on the accuracy of void fraction measurement, and it provides a means of discriminating velocity information of both phases. The algorithm known as Velocity Matched Spectrum (VM Spectrum) is a velocity estimator that stands out from other methods by returning a spectrum of velocities for each interrogated volume sample. Interface detection of free-rising bubbles in quiescent liquid presents some difficulties for interface detection due to abrupt changes in interface inclination. In this work a method based on velocity spectrum curve shape is used to generate a spatial-temporal mapping, which, after spatial filtering, yields an accurate contour of the air-water interface. It is shown that the proposed technique yields a RMS error between 1.71 and 3.39 and a probability of detection failure and false detection between 0.89% and 11.9% in determining the spatial-temporal gas-liquid interface position in the flow of free rising bubbles in stagnant liquid. This result is valid for both free path and with transducer emitting through a metallic plate or a Plexiglas pipe. PMID:24858961

Preliminary drop-tower experiments on liquid-interface geometry in partially filled containers at zero gravity

NASA Technical Reports Server (NTRS)

Smedley, G.

1990-01-01

Plexiglass containers with rounded trapezoidal cross sections were designed and built to test the validity of Concus and Finn's existence theorem (1974, 1983) for a bounded free liquid surface at zero gravity. Experiments were carried out at the NASA Lewis two-second drop tower. Dyed ethanol-water solutions and three immiscible liquid pairs, with one liquid dyed, were tested. High-speed movies were used to record the liquid motion. Liquid rose to the top of the smaller end of the containers when the contact angle was small enough, in agreement with the theory. Liquid interface motion demonstrated a strong dependence on physical properties, including surface roughness and contamination.

Investigation of Artificial Forced Cooling in the Bridgman Crystal Growth of Cadmium Zinc Telluride

NASA Astrophysics Data System (ADS)

Liu, Juncheng; Li, Jiao; Zhang, Guodong; Li, Changxing; Lennon, Craig; Sivananthan, Siva

2007-08-01

The effects of artificial forced cooling on the solid liquid interface and on solute segregation were investigated by modeling the vertical Bridgman method for the single-crystal growth of CdZnTe, taking into consideration effects such as increasing the axial outward heat flux from the crucible bottom, the radial outward heat flux from the crucible wall, and the carbon film thickness on the crucible inner wall. Axial artificially forced cooling noticeably increases convection and the temperature gradient in the melt next to the solid liquid interface, and substantially reduces interface concavity at the initial solidification stage. Interface concavity increases a little when the solidification proceeds further, however. Axial artificially forced cooling reduces radial solute segregation of the initial segment of the grown crystal and slightly increases the solute iso-concentration segment. Radial artificially forced cooling enhances melt convection substantially, affects solid liquid interface concavity only slightly, and hardly affects solute segregation in the grown crystal. Doubling the carbon film thickness weakens convection of the melt in front of the interface, substantially increases interface concavity, and hardly affects solute segregation in the grown crystal.

Interfacial layering and capillary roughness in immiscible liquids.

PubMed

Geysermans, P; Pontikis, V

2010-08-21

The capillary roughness and the atomic density profiles of extended interfaces between immiscible liquids are determined as a function of the interface area by using molecular dynamics and Lennard-Jones (12-6) potentials. We found that with increasing area, the interface roughness diverges logarithmically, thus fitting the theoretical mean-field prediction. In systems small enough for the interfacial roughness not to blur the structural details, atomic density profiles across the fluid interface are layered with correlation length in the range of molecular correlations in liquids. On increasing the system size, the amplitude of the thermally excited position fluctuations of the interface increases, thus causing layering to rapidly vanish, if density profiles are computed without special care. In this work, we present and validate a simple method, operating in the direct space, for extracting from molecular dynamics trajectories the "intrinsic" structure of a fluid interface that is the local density profile of the interface cleaned from capillary wave effects. Estimated values of interfacial properties such as the tension, the intrinsic width, and the lower wavelength limit of position fluctuations are in agreement with results collected from the literature.

Numerical studies of the effects of jet-induced mixing on liquid-vapor interface condensation

NASA Technical Reports Server (NTRS)

Lin, Chin-Shun

1989-01-01

Numerical solutions of jet-induced mixing in a partially full cryogenic tank are presented. An axisymmetric laminar jet is discharged from the central part of the tank bottom toward the liquid-vapor interface. Liquid is withdrawn at the same volume flow rate from the outer part of the tank. The jet is at a temperature lower than the interface, which is maintained at a certain saturation temperature. The interface is assumed to be flat and shear-free and the condensation-induced velocity is assumed to be negligibly small compared with radial interface velocity. Finite-difference method is used to solve the nondimensional form of steady state continuity, momentum, and energy equations. Calculations are conducted for jet Reynolds numbers ranging from 150 to 600 and Prandtl numbers ranging from 0.85 to 2.65. The effects of above stated parameters on the condensation Nusselt and Stanton numbers which characterize the steady-state interface condensation process are investigated. Detailed analysis to gain a better understanding of the fundamentals of fluid mixing and interface condensation is performed.

KENNEDY SPACE CENTER, FLA. - Workers in the Orbiter Processing Facility oversee installation of the liquid oxygen feedline for the 17-inch disconnect on the orbiter Discovery. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

NASA Image and Video Library

2003-11-11

KENNEDY SPACE CENTER, FLA. - Workers in the Orbiter Processing Facility oversee installation of the liquid oxygen feedline for the 17-inch disconnect on the orbiter Discovery. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

Methods and systems for monitoring a solid-liquid interface

DOEpatents

Stoddard, Nathan G.; Clark, Roger F.; Kary, Tim

2010-07-20

Methods and systems are provided for monitoring a solid-liquid interface, including providing a vessel configured to contain an at least partially melted material; detecting radiation reflected from a surface of a liquid portion of the at least partially melted material that is parallel with the liquid surface; measuring a disturbance on the surface; calculating at least one frequency associated with the disturbance; and determining a thickness of the liquid portion based on the at least one frequency, wherein the thickness is calculated based on.times. ##EQU00001## where g is the gravitational constant, w is the horizontal width of the liquid, and f is the at least one frequency.

Improving the Molecular Ion Signal Intensity for In Situ Liquid SIMS Analysis.

PubMed

Zhou, Yufan; Yao, Juan; Ding, Yuanzhao; Yu, Jiachao; Hua, Xin; Evans, James E; Yu, Xiaofei; Lao, David B; Heldebrant, David J; Nune, Satish K; Cao, Bin; Bowden, Mark E; Yu, Xiao-Ying; Wang, Xue-Lin; Zhu, Zihua

2016-12-01

In situ liquid secondary ion mass spectrometry (SIMS) enabled by system for analysis at the liquid vacuum interface (SALVI) has proven to be a promising new tool to provide molecular information at solid-liquid and liquid-vacuum interfaces. However, the initial data showed that useful signals in positive ion spectra are too weak to be meaningful in most cases. In addition, it is difficult to obtain strong negative molecular ion signals when m/z>200. These two drawbacks have been the biggest obstacle towards practical use of this new analytical approach. In this study, we report that strong and reliable positive and negative molecular signals are achievable after optimizing the SIMS experimental conditions. Four model systems, including a 1,8-diazabicycloundec-7-ene (DBU)-base switchable ionic liquid, a live Shewanella oneidensis biofilm, a hydrated mammalian epithelia cell, and an electrolyte popularly used in Li ion batteries were studied. A signal enhancement of about two orders of magnitude was obtained in comparison with non-optimized conditions. Therefore, molecular ion signal intensity has become very acceptable for use of in situ liquid SIMS to study solid-liquid and liquid-vacuum interfaces. Graphical Abstract ᅟ.

Cryogenic hydrogen-induced air liquefaction technologies

NASA Technical Reports Server (NTRS)

Escher, William J. D.

1990-01-01

Extensively utilizing a special advanced airbreathing propulsion archives database, as well as direct contacts with individuals who were active in the field in previous years, a technical assessment of cryogenic hydrogen-induced air liquefaction, as a prospective onboard aerospace vehicle process, was performed and documented. The resulting assessment report is summarized. Technical findings are presented relating the status of air liquefaction technology, both as a singular technical area, and also that of a cluster of collateral technical areas including: compact lightweight cryogenic heat exchangers; heat exchanger atmospheric constituents fouling alleviation; para/ortho hydrogen shift conversion catalysts; hydrogen turbine expanders, cryogenic air compressors and liquid air pumps; hydrogen recycling using slush hydrogen as heat sink; liquid hydrogen/liquid air rocket-type combustion devices; air collection and enrichment systems (ACES); and technically related engine concepts.

Salt induced reduction of lysozyme adsorption at charged interfaces

NASA Astrophysics Data System (ADS)

Göhring, Holger; Paulus, Michael; Salmen, Paul; Wirkert, Florian; Kruse, Theresa; Degen, Patrick; Stuhr, Susan; Rehage, Heinz; Tolan, Metin

2015-06-01

A study of lysozyme adsorption below a behenic acid membrane and at the solid-liquid interface between aqueous lysozyme solution and a silicon wafer in the presence of sodium chloride is presented. The salt concentration was varied between 1 mmol L-1 and 1000 mmol L-1. X-ray reflectivity data show a clear dependence of the protein adsorption on the salt concentration. Increasing salt concentrations result in a decreased protein adsorption at the interface until a complete suppression at high concentrations is reached. This effect can be attributed to a reduced attractive electrostatic interaction between the positively charged proteins and negatively charged surfaces by charge screening. The measurements at the solid-liquid interfaces show a transition from unoriented order of lysozyme in the adsorbed film to an oriented order with the short protein axis perpendicular to the solid-liquid interface with rising salt concentration.

Ab initio study on the dynamics of furfural at the liquid-solid interfaces

NASA Astrophysics Data System (ADS)

Dang, Hongli; Xue, Wenhua; Shields, Darwin; Liu, Yingdi; Jentoft, Friederike; Resasco, Daniel; Wang, Sanwu

2013-03-01

Catalytic biomass conversion sometimes occurs at the liquid-solid interfaces. We report ab initio molecular dynamics simulations at finite temperatures for the catalytic reactions involving furfural at the water-Pd and water-Cu interfaces. We found that, during the dynamic process, the furan ring of furfural prefers to be parallel to the Pd surface and the aldehyde group tends to be away from the Pd surface. On the other hand, at the water-Cu(111) interface, furfural prefers to be tilted to the Cu surface while the aldehyde group is bonded to the surface. In both cases, interaction of liquid water and furfural is identified. The difference of dynamic process of furfural at the two interfaces suggests different catalytic reaction mechanisms for the conversion of furfural, consistent with the experimental investigations. Supported by DOE (DE-SC0004600). Simulations and calculations were performed on XSED's and NERSC's supercomputers

Quantum State-Resolved Collision Dynamics of Nitric Oxide at Ionic Liquid and Molten Metal Surfaces

NASA Astrophysics Data System (ADS)

Zutz, Amelia Marie

Detailed molecular scale interactions at the gas-liquid interface are explored with quantum state-to-state resolved scattering of a jet-cooled beam of NO(2pi1/2; N = 0) from ionic liquid and molten metal surfaces. The scattered distributions are probed via laser-induced fluorescence methods, which yield rotational and spin-orbit state populations that elucidate the dynamics of energy transfer at the gas-liquid interface. These collision dynamics are explored as a function of incident collision energy, surface temperature, scattering angle, and liquid identity, all of which are found to substantially affect the degree of rotational, electronic and vibrational excitation of NO via collisions at the liquid surface. Rotational distributions observed reveal two distinct scattering pathways, (i) molecules that trap, thermalize and eventually desorb from the surface (trapping-desorption, TD), and (ii) those that undergo prompt recoil (impulsive scattering, IS) prior to complete equilibration with the liquid surface. Thermally desorbing NO molecules are found to have rotational temperatures close to, but slightly cooler than the surface temperature, indicative of rotational dependent sticking probabilities on liquid surfaces. Nitric oxide is a radical with multiple low-lying electronic states that serves as an ideal candidate for exploring nonadiabatic state-changing collision dynamics at the gas-liquid interface, which induce significant excitation from ground (2pi1/2) to excited (2pi 3/2) spin-orbit states. Molecular beam scattering of supersonically cooled NO from hot molten metals (Ga and Au, Ts = 300 - 1400 K) is also explored, which provide preliminary evidence for vibrational excitation of NO mediated by thermally populated electron-hole pairs in the hot, conducting liquid metals. The results highlight the presence of electronically nonadiabatic effects and build toward a more complete characterization of energy transfer dynamics at gas-liquid interfaces.

Structure and dynamics of single hydrophobic/ionic heteropolymers at the vapor-liquid interface of water.

PubMed

Vembanur, Srivathsan; Venkateshwaran, Vasudevan; Garde, Shekhar

2014-04-29

We focus on the conformational stability, structure, and dynamics of hydrophobic/charged homopolymers and heteropolymers at the vapor-liquid interface of water using extensive molecular dynamics simulations. Hydrophobic polymers collapse into globular structures in bulk water but unfold and sample a broad range of conformations at the vapor-liquid interface of water. We show that adding a pair of charges to a hydrophobic polymer at the interface can dramatically change its conformations, stabilizing hairpinlike structures, with molecular details depending on the location of the charged pair in the sequence. The translational dynamics of homopolymers and heteropolymers are also different, whereas the homopolymers skate on the interface with low drag, the tendency of charged groups to remain hydrated pulls the heteropolymers toward the liquid side of the interface, thus pinning them, increasing drag, and slowing the translational dynamics. The conformational dynamics of heteropolymers are also slower than that of the homopolymer and depend on the location of the charged groups in the sequence. Conformational dynamics are most restricted for the end-charged heteropolymer and speed up as the charge pair is moved toward the center of the sequence. We rationalize these trends using the fundamental understanding of the effects of the interface on primitive pair-level interactions between two hydrophobic groups and between oppositely charged ions in its vicinity.

Atomistic and Coarse-Grained Modeling of the Adsorption of Graphene Nanoflakes at the Oil-Water Interface.

PubMed

Ardham, Vikram Reddy; Leroy, Frédéric

2018-03-01

The high interfacial tension between two immiscible liquids can provide the necessary driving force for the self-assembly of nanoparticles at the interface. Particularly, the interface between water and oily liquids (hydrocarbon chains) has been exploited to prepare networks of highly interconnected graphene sheets of only a few layers thickness, which are well suited for industrial applications. Studying such complex systems through particle-based simulations could greatly enhance the understanding of the various driving forces in action and could possibly give more control over the self-assembly process. However, the interaction potentials used in particle-based simulations are typically derived by reproducing bulk properties and are therefore not suitable for describing systems dominated by interfaces. To address this issue, we introduce a methodology to derive solid-liquid interaction potentials that yield an accurate representation of the balance between interfacial interactions at atomistic and coarse-grained resolutions. Our approach is validated through its ability to lead to the adsorption of graphene nanoflakes at the interface between water and n-hexane. The development of accurate coarse-grained potentials that our approach enables will allow us to perform large-scale simulations to study the assembly of graphene nanoparticles at the interface between immiscible liquids. Our methodology is illustrated through a simulation of many graphene nanoflakes adsorbing at the interface.

Atomization simulations using an Eulerian-VOF-Lagrangian method

NASA Technical Reports Server (NTRS)

Chen, Yen-Sen; Shang, Huan-Min; Liaw, Paul; Chen, C. P.

1994-01-01

This paper summarizes the technical development and validation of a multiphase computational fluid dynamics (CFD) numerical method using the volume-of-fluid (VOF) model and a Lagrangian tracking model which can be employed to analyze general multiphase flow problems with free surface mechanism. The gas-liquid interface mass, momentum and energy conservations are modeled by continuum surface mechanisms. A new solution method is developed such that the present VOF model can be applied for all-speed flow regimes. The objectives of the present study are to develop and verify the fractional volume-of-fluid cell partitioning approach into a predictor-corrector algorithm and to demonstrate the effectiveness of the present innovative approach by simulating benchmark problems including the coaxial jet atomization.

Vibration-Induced Gas-Liquid Interface Breakup

NASA Astrophysics Data System (ADS)

O'Hern, Timothy; Torczynski, John; Romero, Ed; Shelden, Bion

2010-11-01

Gas-liquid interfaces can be forced to break up when subjected to vibrations within critical ranges of frequency and amplitude. This breakup mechanism was examined experimentally using deep layers of silicone oils over a range of viscosity and sinusoidal, primarily axial vibration conditions that can produce dramatic disturbances at the gas-liquid free surface. Although small-amplitude vibrations produce standing Faraday waves, large-amplitude vibrations produce liquid jets into the gas, droplets pinching off from the jets, gas cavities in the liquid from droplet impact, and bubble transport below the interface. Experiments used several different silicone oils over a range of pressures and vibration conditions. Computational simulations exhibiting similar behavior will be included in the presentation. Applications include liquid fuel rockets, inertial sensing devices, moving vehicles, mixing processes, and acoustic excitation. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

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

PubMed

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.

Pulsed Corona Discharge Induced Hydroxyl Radical Transfer Through the Gas-Liquid Interface.

PubMed

Ajo, Petri; Kornev, Iakov; Preis, Sergei

2017-11-23

The highly energetic electrons in non-thermal plasma generated by gas phase pulsed corona discharge (PCD) produce hydroxyl (OH) radicals via collision reactions with water molecules. Previous work has established that OH radicals are formed at the plasma-liquid interface, making it an important location for the oxidation of aqueous pollutants. Here, by contacting water as aerosol with PCD plasma, it is shown that OH radicals are produced on the gas side of the interface, and not in the liquid phase. It is also demonstrated that the gas-liquid interfacial boundary poses a barrier for the OH radicals, one they need to cross for reactive affinity with dissolved components, and that this process requires a gaseous atomic H scavenger. For gaseous oxidation, a scavenger, oxygen in common cases, is an advantage but not a requirement. OH radical efficiency in liquid phase reactions is strongly temperature dependent as radical termination reaction rates increase with temperature.

Electrostatic Debye layer formed at a plasma-liquid interface

NASA Astrophysics Data System (ADS)

Rumbach, Paul; Clarke, Jean Pierre; Go, David B.

2017-05-01

We construct an analytic model for the electrostatic Debye layer formed at a plasma-liquid interface by combining the Gouy-Chapman theory for the liquid with a simple parabolic band model for the plasma sheath. The model predicts a nonlinear scaling between the plasma current density and the solution ionic strength, and we confirmed this behavior with measurements using a liquid-anode plasma. Plots of the measured current density as a function of ionic strength collapse the data and curve fits yield a plasma electron density of ˜1019m-3 and an electric field of ˜104V /m on the liquid side of the interface. Because our theory is based firmly on fundamental physics, we believe it can be widely applied to many emerging technologies involving the interaction of low-temperature, nonequilibrium plasma with aqueous media, including plasma medicine and various plasma chemical synthesis techniques.

Quantitative analysis of total reflection X-ray fluorescence from finely layered structures using XeRay.

PubMed

Gong, Zhiliang; Kerr, Daniel; Hwang, Hyeondo Luke; Henderson, J Michael; Suwatthee, Tiffany; Slaw, Benjamin R; Cao, Kathleen D; Lin, Binhua; Bu, Wei; Lee, Ka Yee C

2017-03-01

Total reflection x-ray fluorescence (TXRF) is a widely applicable experimental technique for studying chemical element distributions across finely layered structures at extremely high sensitivity. To promote and facilitate scientific discovery using TXRF, we developed a MATLAB-based software package with a graphical user interface, named XeRay, for quick, accurate, and intuitive data analysis. XeRay lets the user model any layered system, each layer with its independent chemical composition and thickness, and enables fine-tuned data fitting. The accuracy of XeRay has been tested in the analysis of TXRF data from both air/liquid interface and liquid/liquid interfacial studies and has been compared to literature results. In an air/liquid interface study, Ca 2+ sequestration was measured at a Langmuir monolayer of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphatidic acid (SOPA) on a buffer solution of 1 mM CaCl 2 at pH 7.5. Data analysis with XeRay reveals that each 1 nm 2 of interfacial area contains 2.38 ± 0.06 Ca 2+ ions, which corresponds to a 1:1 ratio between SOPA headgroups and Ca 2+ ions, consistent with several earlier reports. For the liquid/liquid interface study of Sr 2+ enrichment at the dodecane/surfactant/water interface, analysis using XeRay gives a surface enrichment of Sr 2+ at 68 -5 +6 Å 2 per ion, consistent with the result published for the same dataset.

Influence of gold species (AuCl4(-) and AuCl2(-)) on self-assembly of PS-b-P2VP in solutions and morphology of composite thin films fabricated at the air/liquid interfaces.

PubMed

Zhao, Xingjuan; Wang, Qian; Zhang, Xiaokai; Lee, Yong-Ill; Liu, Hong-Guo

2016-01-21

Composite thin films doped with Au species were fabricated at an air/liquid interface via a series of steps, including the mass transfer of polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) across the liquid/liquid interface between a DMF/CHCl3 solution and an aqueous solution containing either AuCl4(-) or AuCl2(-), self-assembly of PS-b-P2VP in a mixed DMF-water solution, and adsorption and further self-organization of the formed aggregates at the air/liquid interface. This is a new approach for fabricating composite polymer films and can be completed within a very short time. AuCl4(-) and AuCl2(-) ions were found to significantly influence the self-assembly behavior of the block copolymer and the morphologies of the composite films, leading to the formation of nanowire arrays and a foam structure at the air/liquid interface, respectively, which originated from rod-like micelles and microcapsules that had formed in the respective solutions. The effect of the metal complex was analyzed based on the packing parameters of the amphiphilic polymer molecules in different microenvironments and the interactions between the pyridine groups and the metal chloride anions. In addition, these composite thin films exhibited stable and durable performance as heterogeneous catalysts for the hydrogenation of nitroaromatics in aqueous solutions.

Quantitative analysis of total reflection X-ray fluorescence from finely layered structures using XeRay

NASA Astrophysics Data System (ADS)

Gong, Zhiliang; Kerr, Daniel; Hwang, Hyeondo Luke; Henderson, J. Michael; Suwatthee, Tiffany; Slaw, Benjamin R.; Cao, Kathleen D.; Lin, Binhua; Bu, Wei; Lee, Ka Yee C.

2017-03-01

Total reflection x-ray fluorescence (TXRF) is a widely applicable experimental technique for studying chemical element distributions across finely layered structures at extremely high sensitivity. To promote and facilitate scientific discovery using TXRF, we developed a MATLAB-based software package with a graphical user interface, named XeRay, for quick, accurate, and intuitive data analysis. XeRay lets the user model any layered system, each layer with its independent chemical composition and thickness, and enables fine-tuned data fitting. The accuracy of XeRay has been tested in the analysis of TXRF data from both air/liquid interface and liquid/liquid interfacial studies and has been compared to literature results. In an air/liquid interface study, Ca2+ sequestration was measured at a Langmuir monolayer of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphatidic acid (SOPA) on a buffer solution of 1 mM CaCl2 at pH 7.5. Data analysis with XeRay reveals that each 1 nm2 of interfacial area contains 2.38 ± 0.06 Ca2+ ions, which corresponds to a 1:1 ratio between SOPA headgroups and Ca2+ ions, consistent with several earlier reports. For the liquid/liquid interface study of Sr2+ enrichment at the dodecane/surfactant/water interface, analysis using XeRay gives a surface enrichment of Sr2+ at 68-5+6 Å2 per ion, consistent with the result published for the same dataset.

Quantitative analysis of total reflection X-ray fluorescence from finely layered structures using XeRay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gong, Zhiliang; Kerr, Daniel; Hwang, Hyeondo Luke

Total reflection x-ray fluorescence (TXRF) is a widely applicable experimental technique for studying chemical element distributions across finely layered structures at extremely high sensitivity. To promote and facilitate scientific discovery using TXRF, we developed a MATLAB-based software package with a graphical user interface, named XeRay, for quick, accurate, and intuitive data analysis. XeRay lets the user model any layered system, each layer with its independent chemical composition and thickness, and enables fine-tuned data fitting. The accuracy of XeRay has been tested in the analysis of TXRF data from both air/liquid interface and liquid/liquid interfacial studies and has been compared tomore » literature results. In an air/liquid interface study, Ca2+ sequestration was measured at a Langmuir monolayer of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphatidic acid (SOPA) on a buffer solution of 1 mM CaCl2 at pH 7.5. Data analysis with XeRay reveals that each 1 nm2 of interfacial area contains 2.38 ± 0.06 Ca2+ ions, which corresponds to a 1:1 ratio between SOPA headgroups and Ca2+ ions, consistent with several earlier reports. For the liquid/liquid interface study of Sr2+ enrichment at the dodecane/surfactant/water interface, analysis using XeRay gives a surface enrichment of Sr2+ at 68+6-568-5+6 Å2 per ion, consistent with the result published for the same dataset.« less

Where the lay and the technical meet: Using an anthropology of interfaces to explain persistent reproductive health disparities in West Africa.

PubMed

Jaffré, Yannick; Suh, Siri

2016-05-01

Despite impressive global investment in reproductive health programs in West Africa, maternal mortality remains unacceptably high and obstetric care is often inadequate. Fertility is among the highest in the world, while contraceptive prevalence remains among the lowest. This paper explores the social and technical dimensions of this situation. We argue that effective reproductive health programs require analyzing the interfaces between technical programs and the social logics and behaviors of health professionals and client populations. Significant gaps between health programs' goals and the behaviors of patients and health care professionals have been observed. While public health projects aim to manage reproduction, sexuality, fertility, and professional practices are regulated socially. Such projects may target technical practices, but access to care is greatly influenced by social norms and ethics. This paper shows how an empirical anthropology that investigates the social and technical interfaces of reproduction can contribute to improved global health. Copyright © 2016 Elsevier Ltd. All rights reserved.

Cryogenic hydrogen-induced air-liquefaction technologies for combined-cycle propulsion applications

NASA Technical Reports Server (NTRS)

Escher, William J. D.

1992-01-01

Given here is a technical assessment of the realization of cryogenic hydrogen induced air liquefaction technologies in a prospective onboard aerospace vehicle process setting. The technical findings related to the status of air liquefaction technologies are reviewed. Compact lightweight cryogenic heat exchangers, heat exchanger atmospheric constituent fouling alleviation measures, para/ortho-hydrogen shift-conversion catalysts, cryogenic air compressors and liquid air pumps, hydrogen recycling using slush hydrogen as a heat sink, liquid hydrogen/liquid air rocket-type combustion devices, and technically related engine concepts are discussed. Much of the LACE work is related to aerospaceplane propulsion concepts that were developed in the 1960's. Emphasis is placed on the Liquid Air Cycle Engine (LACE).

Formative evaluation of a mobile liquid portion size estimation interface for people with varying literacy skills.

PubMed

Chaudry, Beenish Moalla; Connelly, Kay; Siek, Katie A; Welch, Janet L

2013-12-01

Chronically ill people, especially those with low literacy skills, often have difficulty estimating portion sizes of liquids to help them stay within their recommended fluid limits. There is a plethora of mobile applications that can help people monitor their nutritional intake but unfortunately these applications require the user to have high literacy and numeracy skills for portion size recording. In this paper, we present two studies in which the low- and the high-fidelity versions of a portion size estimation interface, designed using the cognitive strategies adults employ for portion size estimation during diet recall studies, was evaluated by a chronically ill population with varying literacy skills. The low fidelity interface was evaluated by ten patients who were all able to accurately estimate portion sizes of various liquids with the interface. Eighteen participants did an in situ evaluation of the high-fidelity version incorporated in a diet and fluid monitoring mobile application for 6 weeks. Although the accuracy of the estimation cannot be confirmed in the second study but the participants who actively interacted with the interface showed better health outcomes by the end of the study. Based on these findings, we provide recommendations for designing the next iteration of an accurate and low literacy-accessible liquid portion size estimation mobile interface.

HPTAM, a two-dimensional Heat Pipe Transient Analysis Model, including the startup from a frozen state

NASA Technical Reports Server (NTRS)

Tournier, Jean-Michel; El-Genk, Mohamed S.

1995-01-01

A two-dimensional Heat Pipe Transient Analysis Model, 'HPTAM,' was developed to simulate the transient operation of fully-thawed heat pipes and the startup of heat pipes from a frozen state. The model incorporates: (a) sublimation and resolidification of working fluid; (b) melting and freezing of the working fluid in the porous wick; (c) evaporation of thawed working fluid and condensation as a thin liquid film on a frozen substrate; (d) free-molecule, transition, and continuum vapor flow regimes, using the Dusty Gas Model; (e) liquid flow and heat transfer in the porous wick; and (f) thermal and hydrodynamic couplings of phases at their respective interfaces. HPTAM predicts the radius of curvature of the liquid meniscus at the liquid-vapor interface and the radial location of the working fluid level (liquid or solid) in the wick. It also includes the transverse momentum jump condition (capillary relationship of Pascal) at the liquid-vapor interface and geometrically relates the radius of curvature of the liquid meniscus to the volume fraction of vapor in the wick. The present model predicts the capillary limit and partial liquid recess (dryout) in the evaporator wick, and incorporates a liquid pooling submodel, which simulates accumulation of the excess liquid in the vapor core at the condenser end.

Advanced Microscopic Integrated Thermocouple Arrays

NASA Technical Reports Server (NTRS)

Pettigrew, Penny J.

1999-01-01

The purpose of this research is to develop and refine a technique for making microscopic thermocouple arrays for use in measuring the temperature gradient across a solid-liquid interface during the solidification process. Current thermocouple technology does not allow for real-time measurements across the interface due to the prohibitive size of available thermocouples. Microscopic thermocouple arrays will offer a much greater accuracy and resolution of temperature measurements across the solid-liquid interface which will lead to a better characterization of the solidification process and interface reaction which affect the properties of the resulting material.

Electrochemical ion transfer across liquid/liquid interfaces confined within solid-state micropore arrays--simulations and experiments.

PubMed

Strutwolf, Jörg; Scanlon, Micheál D; Arrigan, Damien W M

2009-01-01

Miniaturised liquid/liquid interfaces provide benefits for bioanalytical detection with electrochemical methods. In this work, microporous silicon membranes which can be used for interface miniaturisation were characterized by simulations and experiments. The microporous membranes possessed hexagonal arrays of pores with radii between 10 and 25 microm, a pore depth of 100 microm and pore centre-to-centre separations between 99 and 986 microm. Cyclic voltammetry was used to monitor ion transfer across arrays of micro-interfaces between two immiscible electrolyte solutions (microITIES) formed at these membranes, with the organic phase present as an organogel. The results were compared to computational simulations taking into account mass transport by diffusion and encompassing diffusion to recessed interfaces and overlapped diffusion zones. The simulation and experimental data were both consistent with the situation where the location of the liquid/liquid (l/l) interface was on the aqueous side of the silicon membrane and the pores were filled with the organic phase. While the current for the forward potential scan (transfer of the ion from the aqueous phase to the organic phase) was strongly dependent on the location of the l/l interface, the current peak during the reverse scan (transfer of the ion from the organic phase to the aqueous phase) was influenced by the ratio of the transferring ion's diffusion coefficients in both phases. The diffusion coefficient of the transferring ion in the gelified organic phase was ca. nine times smaller than in the aqueous phase. Asymmetric cyclic voltammogram shapes were caused by the combined effect of non-symmetrical diffusion (spherical and linear) and by the inequality of the diffusion coefficient in both phases. Overlapping diffusion zones were responsible for the observation of current peaks instead of steady-state currents during the forward scan. The characterisation of the diffusion behaviour is an important requirement for application of these silicon membranes in electroanalytical chemistry.

Atomic study on the ordered structure in Al melts induced by liquid/substrate interface with Ti solute

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, H. L.; Han, Y. F., E-mail: yfhan@sjtu.edu.cn, E-mail: bdsun@sjtu.edu.cn; Zhou, W.

2015-01-26

Atomic ordering in Al melts induced by liquid/substrate interface with Ti solute was investigated by ab initio molecular dynamics simulations and in-situ synchrotron X-ray diffraction. It is predicted that deformed nanoscale ordering Al layers with a rhombohedral-centered hexagonal structure (R3{sup ¯}m space group) instead of the intrinsic fcc structure (Fm3{sup ¯}m space group) form on substrate at temperature above Al liquids. With Al atoms stacking away from the interface, the ordering structure reaches a critical thickness, which inhibits the consecutive stacking of Al atoms on substrates. The locally stacking reconstruction induced by Ti atom relieves the accumulated elastic strain energymore » in ordered Al layers, facilitating fully heterogeneous nucleation on substrate beyond the deformed ordering Al layer around the melting point. The roles of liquid/substrate interface with Ti solute in the physical behavior of heterogeneous nucleation on substrate were discussed.« less

Wetting, meniscus structure, and capillary interactions of microspheres bound to a cylindrical liquid interface.

PubMed

Kim, Paul Y; Dinsmore, Anthony D; Hoagland, David A; Russell, Thomas P

2018-03-14

Wetting, meniscus structure, and capillary interactions for polystyrene microspheres deposited on constant curvature cylindrical liquid interfaces, constructed from nonvolatile ionic or oligomeric liquids, were studied by optical interferometry and optical microscopy. The liquid interface curvature resulted from the preferential wetting of finite width lines patterned onto planar silicon substrates. Key variables included sphere diameter, nominal (or average) contact angle, and deviatoric interfacial curvature. Menisci adopted the quadrupolar symmetry anticipated by theory, with interfacial deformation closely following predicted dependences on sphere diameter and nominal contact angle. Unexpectedly, the contact angle was not constant locally around the contact line, the nominal contact angle varied among seemingly identical spheres, and the maximum interface deviation did not follow the predicted dependence on deviatoric interfacial curvature. Instead, this deviation was up to an order-of-magnitude larger than predicted. Trajectories of neighboring microspheres visually manifested quadrupole-quadrupole interactions, eventually producing square sphere packings that foreshadow interfacial assembly as a potential route to hierarchical 2D particle structures.

How are soap bubbles blown? Fluid dynamics of soap bubble blowing

NASA Astrophysics Data System (ADS)

Davidson, John; Lambert, Lori; Sherman, Erica; Wei, Timothy; Ryu, Sangjin

2013-11-01

Soap bubbles are a common interfacial fluid dynamics phenomenon having a long history of delighting not only children and artists but also scientists. In contrast to the dynamics of liquid droplets in gas and gas bubbles in liquid, the dynamics of soap bubbles has not been well documented. This is possibly because studying soap bubbles is more challenging due to there existing two gas-liquid interfaces. Having the thin-film interface seems to alter the characteristics of the bubble/drop creation process since the interface has limiting factors such as thickness. Thus, the main objective of this study is to determine how the thin-film interface differentiates soap bubbles from gas bubbles and liquid drops. To investigate the creation process of soap bubbles, we constructed an experimental model consisting of air jet flow and a soap film, which consistently replicates the conditions that a human produces when blowing soap bubbles, and examined the interaction between the jet and the soap film using the high-speed videography and the particle image velocimetry.

Pressure cell for investigations of solid-liquid interfaces by neutron reflectivity.

PubMed

Kreuzer, Martin; Kaltofen, Thomas; Steitz, Roland; Zehnder, Beat H; Dahint, Reiner

2011-02-01

We describe an apparatus for measuring scattering length density and structure of molecular layers at planar solid-liquid interfaces under high hydrostatic pressure conditions. The device is designed for in situ characterizations utilizing neutron reflectometry in the pressure range 0.1-100 MPa at temperatures between 5 and 60 °C. The pressure cell is constructed such that stratified molecular layers on crystalline substrates of silicon, quartz, or sapphire with a surface area of 28 cm(2) can be investigated against noncorrosive liquid phases. The large substrate surface area enables reflectivity to be measured down to 10(-5) (without background correction) and thus facilitates determination of the scattering length density profile across the interface as a function of applied load. Our current interest is on the stability of oligolamellar lipid coatings on silicon surfaces against aqueous phases as a function of applied hydrostatic pressure and temperature but the device can also be employed to probe the structure of any other solid-liquid interface.

Interaction of monovalent ions with the water liquid-vapor interface - A molecular dynamics study

NASA Technical Reports Server (NTRS)

Wilson, Michael A.; Pohorille, Andrew

1991-01-01

Results of molecular dynamics calculations are presented for a series of ions at infinite dilution near the water liquid-vapor interface. The free energies of ion transfer from the bulk to the interface are discussed, as are the accompanying changes of water structure at the surface and ion mobilities as a function of their proximity to the interface. It is shown that simple dielectric models do not provide an accurate description of ions at the water surface. The results of the study should be useful in the development of better models incorporating the shape and molecular structure of the interface.

Modeling of ultrasound transmission through a solid-liquid interface comprising a network of gas pockets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paumel, K.; Baque, F.; Moysan, J.

Ultrasonic inspection of sodium-cooled fast reactor requires a good acoustic coupling between the transducer and the liquid sodium. Ultrasonic transmission through a solid surface in contact with liquid sodium can be complex due to the presence of microscopic gas pockets entrapped by the surface roughness. Experiments are run using substrates with controlled roughness consisting of a network of holes and a modeling approach is then developed. In this model, a gas pocket stiffness at a partially solid-liquid interface is defined. This stiffness is then used to calculate the transmission coefficient of ultrasound at the entire interface. The gas pocket stiffnessmore » has a static, as well as an inertial component, which depends on the ultrasonic frequency and the radiative mass.« less

Cryogenic hydrogen-induced air-liquefaction technologies

NASA Technical Reports Server (NTRS)

Escher, William J. D.

1990-01-01

Extensive use of a special advanced airbreathing propulsion archives data base, as well as direct contacts with individuals who were active in the field in previous years, a technical assessment of cryogenic hydrogen induced air liquefaction, as a prospective onboard aerospace vehicle process, was performed and documented in 1986. The resulting assessment report is summarized. Technical findings relating the status of air liquefaction technology are presented both as a singular technical area, and also as that of a cluster of collateral technical areas including: Compact lightweight cryogenic heat exchangers; Heat exchanger atmospheric constituents fouling alleviation; Para/ortho hydrogen shift conversion catalysts; Hydrogen turbine expanders, cryogenic air compressors and liquid air pumps; Hydrogen recycling using slush hydrogen as heat sinks; Liquid hydrogen/liquid air rocket type combustion devices; Air Collection and Enrichment System (ACES); and Technically related engine concepts.

Shuttle payload interface verification equipment study. Volume 2: Technical document, part 1

NASA Technical Reports Server (NTRS)

1976-01-01

The technical analysis is reported that was performed during the shuttle payload interface verification equipment study. It describes: (1) the background and intent of the study; (2) study approach and philosophy covering all facets of shuttle payload/cargo integration; (3)shuttle payload integration requirements; (4) preliminary design of the horizontal IVE; (5) vertical IVE concept; and (6) IVE program development plans, schedule and cost. Also included is a payload integration analysis task to identify potential uses in addition to payload interface verification.

Determinative factors of competitive advantage between aerobic bacteria for niches at the air-liquid interface.

PubMed

Yamamoto, Kyosuke; Haruta, Shin; Kato, Souichiro; Ishii, Masaharu; Igarashi, Yasuo

2010-01-01

We focused on bacterial interspecies relationships at the air-liquid interface where the formation of pellicles by aerobes was observed. Although an obligate aerobe (Brevibacillus sp. M1-5) was initially dominant in the pellicle population, a facultative aerobe (Pseudoxanthomonas sp. M1-3) emerged and the viability of M1-5 rapidly decreased due to severe competition for oxygen. Supplementation of the medium with carbohydrates allowed the two species to coexist at the air-liquid interface. These results indicate that the population dynamics within pellicles are primarily governed by oxygen utilization which was affected by a combination of carbon sources.

KENNEDY SPACE CENTER, FLA. - Viewed from inside the aft section of the orbiter Discovery, a worker installs the liquid oxygen feedline for the 17-inch disconnect, coming up from below. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

NASA Image and Video Library

2003-11-11

KENNEDY SPACE CENTER, FLA. - Viewed from inside the aft section of the orbiter Discovery, a worker installs the liquid oxygen feedline for the 17-inch disconnect, coming up from below. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

Progress in Applied Surface, Interface and Thin Film Science 2015. Solar Renewable Energy News IV, November 23-26, 2015, Florence, Italy (SURFINT-SREN IV)

NASA Astrophysics Data System (ADS)

2017-02-01

The main goal of the conference is to contribute to new knowledge in surface, interface, ultra-thin films and very-thin films science of inorganic and organic materials by the most rapid interactive manner - by direct communication among scientists of corresponding research fields. The list of topics indicates that conference interests cover the development of basic theoretical physical and chemical principles and performance of surfaces-, thin films-, and interface-related procedures, and corresponding experimental research on atomic scale. Topical results are applied at development of new inventive industrial equipments needed for investigation of electrical, optical, and structural properties, and other parameters of atomic-size research objects. The conference range spreads, from physical point of view, from fundamental research done on sub-atomic and quantum level to production of devices built on new physical principles. The conference topics include also presentation of principally new devices in following fields: solar cells, liquid crystal displays, high-temperature superconductivity, and sensors. During the event, special attention will be given to evaluation of scientific and technical quality of works prepared by PhD students, to deep ecological meaning of solar cell energy production, and to exhibitions of companies.

Massive radius-dependent flow slippage in carbon nanotubes.

PubMed

Secchi, Eleonora; Marbach, Sophie; Niguès, Antoine; Stein, Derek; Siria, Alessandro; Bocquet, Lydéric

2016-09-08

Measurements and simulations have found that water moves through carbon nanotubes at exceptionally high rates owing to nearly frictionless interfaces. These observations have stimulated interest in nanotube-based membranes for applications including desalination, nano-filtration and energy harvesting, yet the exact mechanisms of water transport inside the nanotubes and at the water-carbon interface continue to be debated because existing theories do not provide a satisfactory explanation for the limited number of experimental results available so far. This lack of experimental results arises because, even though controlled and systematic studies have explored transport through individual nanotubes, none has met the considerable technical challenge of unambiguously measuring the permeability of a single nanotube. Here we show that the pressure-driven flow rate through individual nanotubes can be determined with unprecedented sensitivity and without dyes from the hydrodynamics of water jets as they emerge from single nanotubes into a surrounding fluid. Our measurements reveal unexpectedly large and radius-dependent surface slippage in carbon nanotubes, and no slippage in boron nitride nanotubes that are crystallographically similar to carbon nanotubes, but electronically different. This pronounced contrast between the two systems must originate from subtle differences in the atomic-scale details of their solid-liquid interfaces, illustrating that nanofluidics is the frontier at which the continuum picture of fluid mechanics meets the atomic nature of matter.

Massive radius-dependent flow slippage in carbon nanotubes

NASA Astrophysics Data System (ADS)

Secchi, Eleonora; Marbach, Sophie; Niguès, Antoine; Stein, Derek; Siria, Alessandro; Bocquet, Lydéric

2016-09-01

Measurements and simulations have found that water moves through carbon nanotubes at exceptionally high rates owing to nearly frictionless interfaces. These observations have stimulated interest in nanotube-based membranes for applications including desalination, nano-filtration and energy harvesting, yet the exact mechanisms of water transport inside the nanotubes and at the water-carbon interface continue to be debated because existing theories do not provide a satisfactory explanation for the limited number of experimental results available so far. This lack of experimental results arises because, even though controlled and systematic studies have explored transport through individual nanotubes, none has met the considerable technical challenge of unambiguously measuring the permeability of a single nanotube. Here we show that the pressure-driven flow rate through individual nanotubes can be determined with unprecedented sensitivity and without dyes from the hydrodynamics of water jets as they emerge from single nanotubes into a surrounding fluid. Our measurements reveal unexpectedly large and radius-dependent surface slippage in carbon nanotubes, and no slippage in boron nitride nanotubes that are crystallographically similar to carbon nanotubes, but electronically different. This pronounced contrast between the two systems must originate from subtle differences in the atomic-scale details of their solid-liquid interfaces, illustrating that nanofluidics is the frontier at which the continuum picture of fluid mechanics meets the atomic nature of matter.

Evaluation of air-liquid interface exposure systems for in vitro assessment of airborne pollutants

EPA Science Inventory

Exposure of cells to airborne pollutants at the air-liquid interface (ALI) is a more realistic approach than exposures of submerged cells. The published literature, however, describes irreproducible and/or unrealistic experimental conditions using ALI systems. We have compared fi...

Optimizing the NASA Technical Report Server

NASA Technical Reports Server (NTRS)

Nelson, Michael L.; Maa, Ming-Hokng

1996-01-01

The NASA Technical Report Server (NTRS), a World Wide Web report distribution NASA technical publications service, is modified for performance enhancement, greater protocol support, and human interface optimization. Results include: Parallel database queries, significantly decreasing user access times by an average factor of 2.3; access from clients behind firewalls and/ or proxies which truncate excessively long Uniform Resource Locators (URLs); access to non-Wide Area Information Server (WAIS) databases and compatibility with the 239-50.3 protocol; and a streamlined user interface.

Microorganism Nutrition Processes as a General Route for the Preparation of Bionic Nanocomposites Based on Intractable Polymers.

PubMed

Valentini, L; Bon, S Bittolo; Pugno, N M

2016-08-31

In this paper the fermentation process activated by living microorganisms of the baker's yeast is proposed as a facile assembly method of hybrid nanoparticles at liquid interface. Water dispersion of commercial baker's yeast extract used for bread production, graphene nanoplatelets (GNPs), and carbon nanotubes (CNTs) were added to oil/water interface; when the yeast is activated by adding sugar, the byproduct carbon dioxide bubbles migrate from the water phase to the oil/water interface generating a floating nanostructured film at liquid interface where it is trapped. Starting from this simple method, we propose a general approach for the stabilization of intractable poly(etheretherketone) polymeric particles with GNPs and CNTs at immiscible liquid interface. This process allowed the formation of sintered porous composites with improved mechanical properties. The porous structure of the composites gave rise to a low thermal conductivity making them good candidates for thermal insulating applications. Liquid absorption by these porous composites has been also reported. We believe that this new approach may have applications in the large scale fabrication of nanomaterials and is particularly suited for the preparation of nanocomposites starting from polymers that are intractable by solvent casting.

Perspective: Surface freezing in water: A nexus of experiments and simulations

NASA Astrophysics Data System (ADS)

Haji-Akbari, Amir; Debenedetti, Pablo G.

2017-08-01

Surface freezing is a phenomenon in which crystallization is enhanced at a vapor-liquid interface. In some systems, such as n-alkanes, this enhancement is dramatic and results in the formation of a crystalline layer at the free interface even at temperatures slightly above the equilibrium bulk freezing temperature. There are, however, systems in which the enhancement is purely kinetic and only involves faster nucleation at or near the interface. The first, thermodynamic, type of surface freezing is easier to confirm in experiments, requiring only the verification of the existence of crystalline order at the interface. The second, kinetic, type of surface freezing is far more difficult to prove experimentally. One material that is suspected of undergoing the second type of surface freezing is liquid water. Despite strong indications that the freezing of liquid water is kinetically enhanced at vapor-liquid interfaces, the findings are far from conclusive, and the topic remains controversial. In this perspective, we present a simple thermodynamic framework to understand conceptually and distinguish these two types of surface freezing. We then briefly survey fifteen years of experimental and computational work aimed at elucidating the surface freezing conundrum in water.

Effects of temperature, pH, and ionic strength on the adsorption of nanoparticles at liquid-liquid interfaces

NASA Astrophysics Data System (ADS)

Ferdous, Sultana; Ioannidis, Marios A.; Henneke, Dale E.

2012-05-01

The effects of temperature, pH and sodium chloride (NaCl) concentration on the equilibrium and dynamic interfacial tension (IFT) of 4.4-nm gold nanoparticles capped with n-dodecanethiol at hydrocarbon-water interfaces was studied. The pendant drop technique was used to study the adsorption properties of these nanoparticles at the hexane-water and nonane-water interfaces. The physical size of the gold nanoparticles was determined by TEM image analysis. The interfacial properties of mixtures of these nanoparticles, having different sizes and capping agents, were then studied. The addition of NaCl was found to cause a decrease of the equilibrium and dynamic IFT greater than that which accompanies the adsorption of nanoparticles at the interface in the absence of NaCl. Although IFT values for acidic and neutral conditions were found to be similar, a noticeable decrease in the IFT was found for more basic conditions. Increasing the temperature of the system was found to cause an increase in both dynamic and equilibrium IFT values. These findings have implications for the self-assembly of functionalized gold nanoparticles at liquid-liquid interfaces.

Benard and Marangoni convection in multiple liquid layers

NASA Technical Reports Server (NTRS)

Koster, Jean N.; Prakash, A.; Fujita, D.; Doi, T.

1992-01-01

Convective fluid dynamics of immiscible double and triple liquid layers are considered. First results on multilayer convective flow, in preparation for spaceflight experiment aboard IML-2 (International Microgravity Laboratory), are discussed. Convective flow in liquid layers with one or two horizontal interfaces with heat flow applied parallel to them is one of the systems investigated. The second system comprises two horizontally layered immiscible liquids heated from below and cooled from above, that is, heat flow orthogonal to the interface. In this system convection results due to the classical Benard instability.

Spectacular Rate Enhancement of the Diels-Alder Reaction at the Ionic Liquid/n-Hexane Interface.

PubMed

Beniwal, Vijay; Manna, Arpan; Kumar, Anil

2016-07-04

The use of the ionic liquid/n-hexane interface as a new class of reaction medium for the Diels-Alder reaction gives large rate enhancements of the order of 10(6) to 10(8) times and high stereoselectivity, as compared to homogeneous media. The rate enhancement is attributed to the H-bonding abilities and polarities of the ionic liquids, whereas the hydrophobicity of ionic liquids was considered to be the factor in controlling stereoselectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Using “Tender” x-ray ambient pressure x-Ray photoelectron spectroscopy as a direct probe of solid-liquid interface

DOE PAGES

Axnanda, Stephanus; Crumlin, Ethan J.; Mao, Baohua; ...

2015-05-07

We report a new method to probe the solid-liquid interface through the use of a thin liquid layer on a solid surface. An ambient pressure XPS (AP-XPS) endstation that is capable of detecting high kinetic energy photoelectrons (7 keV) at a pressure up to 110 Torr has been constructed and commissioned. Additionally, we have deployed a “dip & pull” method to create a stable nanometers-thick aqueous electrolyte on platinum working electrode surface. Combining the newly constructed AP-XPS system, “dip & pull” approach, with a “tender” X-ray synchrotron source (2 keV–7 keV), we are able to access the interface between liquidmore » and solid dense phases with photoelectrons and directly probe important phenomena occurring at the narrow solid-liquid interface region in an electrochemical system. Using this approach, we have performed electrochemical oxidation of the Pt electrode at an oxygen evolution reaction (OER) potential. Under this potential, we observe the formation of both Pt²⁺ and Pt⁴⁺ interfacial species on the Pt working electrode in situ. We believe this thin-film approach and the use of “tender” AP-XPS highlighted in this study is an innovative new approach to probe this key solid-liquid interface region of electrochemistry.« less

Using “Tender” x-ray ambient pressure x-Ray photoelectron spectroscopy as a direct probe of solid-liquid interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Axnanda, Stephanus; Crumlin, Ethan J.; Mao, Baohua

We report a new method to probe the solid-liquid interface through the use of a thin liquid layer on a solid surface. An ambient pressure XPS (AP-XPS) endstation that is capable of detecting high kinetic energy photoelectrons (7 keV) at a pressure up to 110 Torr has been constructed and commissioned. Additionally, we have deployed a “dip & pull” method to create a stable nanometers-thick aqueous electrolyte on platinum working electrode surface. Combining the newly constructed AP-XPS system, “dip & pull” approach, with a “tender” X-ray synchrotron source (2 keV–7 keV), we are able to access the interface between liquidmore » and solid dense phases with photoelectrons and directly probe important phenomena occurring at the narrow solid-liquid interface region in an electrochemical system. Using this approach, we have performed electrochemical oxidation of the Pt electrode at an oxygen evolution reaction (OER) potential. Under this potential, we observe the formation of both Pt²⁺ and Pt⁴⁺ interfacial species on the Pt working electrode in situ. We believe this thin-film approach and the use of “tender” AP-XPS highlighted in this study is an innovative new approach to probe this key solid-liquid interface region of electrochemistry.« less

A Mathematical Model for the Multiphase Transport and Reaction Kinetics in a Ladle with Bottom Powder Injection

NASA Astrophysics Data System (ADS)

Lou, Wentao; Zhu, Miaoyong

2017-12-01

A computation fluid dynamics-population balance model-simultaneous reaction model (CFD-PBM-SRM) coupled model has been proposed to study the multiphase flow behavior and refining reaction kinetics in a ladle with bottom powder injection, and some new and important phenomena and mechanisms are presented. For the multiphase flow behavior, the effects of bubbly plume flow, powder particle motion, particle-particle collision and growth, particle-bubble collision and adhesion, and powder particle removal into top slag are considered. For the reaction kinetics, the mechanisms of multicomponent simultaneous reactions, including Al, S, Si, Mn, Fe, and O, at the multi-interface, including top slag-liquid steel interface, air-liquid steel interface, powder droplet-liquid steel interface, and bubble-liquid steel interface, are presented, and the effect of sulfur solubility in the powder droplet on the desulfurization is also taken into account. Model validation is carried out using hot tests in a 2-t induction furnace with bottom powder injection. The result shows that the powder particles gradually disperse in the entire furnace; in the vicinity of the bottom slot plugs, the desulfurization product CaS is liquid phase, while in the upper region of the furnace, the desulfurization product CaS is solid phase. The predicted sulfur contents by the present model agree well with the measured data in the 2-t furnace with bottom powder injection.

Strong collective attraction in colloidal clusters on a liquid-air interface.

PubMed

Pergamenshchik, V M

2009-01-01

It is shown that in a cluster of many colloids, trapped at a liquid-air interface, the well-known vertical-force-induced pairwise logarithmic attraction changes to a strongly enhanced power-law attraction. In large two-dimensional clusters, the attraction energy scales as the inverse square of the distance between colloids. The enhancement is given by the ratio eta = (square of the capillary length) / (interface surface area per colloid) and can be as large as 10;{5} . This explains why a very small vertical force on colloids, which is too weak to bring two of them together, can stabilize many-body structures on a liquid-air interface. The profile of a cluster is shown to consist of a large slow collective envelope modulated by a fast low-amplitude perturbation due to individual colloids. A closed equation for the slow envelope, which incorporates an arbitrary power-law repulsion between colloids, is derived. For example, this equation is solved for a large circular cluster with the hard-core colloid repulsion. It is suggested that the predicted effect is responsible for mysterious stabilization of colloidal structures observed in experiments on a surface of isotropic liquid and nematic liquid crystal.

Friction at ice-Ih / water interfaces

NASA Astrophysics Data System (ADS)

Louden, Patrick B.; Gezelter, J. Daniel

We present evidence that the prismatic and secondary prism facets of ice-Ih crystals possess structural features that alter the effective hydrophilicity of the ice / water interface. This is shown through molecular dynamics simulations of solid-liquid friction, where the prismatic { 10 1 0 } , secondary prism { 11 2 0 } , basal { 0001 } , and pyramidal { 20 2 1 } facets are drawn through liquid water. We find that the two prismatic facets exhibit differential solid-liquid friction coefficients when compared with the basal and pyramidal facets. These results are complemented by a model solid/liquid interface with tunable hydrophilicity. These simulations provide evidence that the two prismatic faces have a significantly smaller effective surface area in contact with the liquid water. The ice / water interfacial widths for all four crystal facets are similar (using both structural and dynamic measures), and were found to be independent of the shear rate. Additionally, decomposition of orientational time correlation functions show position-dependence for the short- and longer-time decay components close to the interface. Support for this project was provided by the National Science Foundation under Grant CHE-1362211. Computational time was provided by the Center for Research Computing (CRC) at the University of Notre Dame.

Phase-field model of vapor-liquid-solid nanowire growth

NASA Astrophysics Data System (ADS)

Wang, Nan; Upmanyu, Moneesh; Karma, Alain

2018-03-01

We present a multiphase-field model to describe quantitatively nanowire growth by the vapor-liquid-solid (VLS) process. The free-energy functional of this model depends on three nonconserved order parameters that distinguish the vapor, liquid, and solid phases and describe the energetic properties of various interfaces, including arbitrary forms of anisotropic γ plots for the solid-vapor and solid-liquid interfaces. The evolution equations for those order parameters describe basic kinetic processes including the rapid (quasi-instantaneous) equilibration of the liquid catalyst to a droplet shape with constant mean curvature, the slow incorporation of growth atoms at the droplet surface, and crystallization within the droplet. The standard constraint that the sum of the phase fields equals unity and the conservation of the number of catalyst atoms, which relates the catalyst volume to the concentration of growth atoms inside the droplet, are handled via separate Lagrange multipliers. An analysis of the model is presented that rigorously maps the phase-field equations to a desired set of sharp-interface equations for the evolution of the phase boundaries under the constraint of force balance at three-phase junctions (triple points) given by the Young-Herring relation that includes torque term related to the anisotropy of the solid-liquid and solid-vapor interface excess free energies. Numerical examples of growth in two dimensions are presented for the simplest case of vanishing crystalline anisotropy and the more realistic case of a solid-liquid γ plot with cusped minima corresponding to two sets of (10 ) and (11 ) facets. The simulations reproduce many of the salient features of nanowire growth observed experimentally, including growth normal to the substrate with tapering of the side walls, transitions between different growth orientations, and crawling growth along the substrate. They also reproduce different observed relationships between the nanowire growth velocity and radius depending on the growth condition. For the basic normal growth mode, the steady-state solid-liquid interface tip shape consists of a main facet intersected by two truncated side facets ending at triple points. The ratio of truncated and main facet lengths are in quantitative agreement with the prediction of sharp-interface theory that is developed here for faceted nanowire growth in two dimensions.

Simulation of an electrowetting solar concentration cell

NASA Astrophysics Data System (ADS)

Khan, Iftekhar; Rosengarten, Gary

2015-09-01

Electrowetting control of liquid lenses has emerged as a novel approach for solar tracking and concentration. Recent studies have demonstrated the concept of steering sunlight using thin electrowetting cells without the use of any bulky mechanical equipment. Effective application of this technique may facilitate designing thin and flat solar concentrators. Understanding the behavior of liquid-liquid and liquid-solid interface of the electrowetting cell through trial and error experimental processes is not efficient and is time consuming. In this paper, we present a simulation model to predict the liquid-liquid and liquid-solid interface behavior of electrowetting cell as a function of various parameters such as applied voltage, dielectric constant, cell size etc. We used Comsol Multiphysics simulations incorporating experimental data of different liquids. We have designed both two dimensional and three dimensional simulation models, which predict the shape of the liquid lenses. The model calculates the contact angle using the Young-Lippman equation and uses a moving mesh interface to solve the Navier-stokes equation with Navier slip wall boundary condition. Simulation of the electric field from the electrodes is coupled to the Young-Lippman equation. The model can also be used to determine operational characteristics of other MEMS electrowetting devices such as electrowetting display, optical switches, electronic paper, electrowetting Fresnel lens etc.

Wetting of cholesteric liquid crystals.

PubMed

Silvestre, Nuno M; Figueirinhas Pereira, Maria Carolina; Bernardino, Nelson R; Telo da Gama, Margarida M

2016-02-01

We investigate theoretically the wetting properties of cholesteric liquid crystals at a planar substrate. If the properties of substrate and of the interface are such that the cholesteric layers are not distorted, the wetting properties are similar to those of a nematic liquid crystal. If, on the other hand, the anchoring conditions force the distortion of the liquid crystal layers the wetting properties are altered, the free cholesteric-isotropic interface is non-planar and there is a layer of topological defects close to the substrate. These deformations can either promote or hinder the wetting of the substrate by a cholesteric, depending on the properties of the cholesteric liquid crystal.

Intermolecular network analysis of the liquid and vapor interfaces of pentane and water: microsolvation does not trend with interfacial properties.

PubMed

Ghadar, Yasaman; Clark, Aurora E

2014-06-28

Liquid:vapor and liquid:liquid interfaces exhibit complex organizational structure and dynamics at the molecular level. In the case of water and organic solvents, the hydrophobicity of the organic, its conformational flexibility, and compressibility, all influence interfacial properties. This work compares the interfacial tension, width, molecular conformations and orientations at the vapor and aqueous liquid interfaces of two solvents, n-pentane and neopentane, whose varying molecular shapes can lead to significantly different interfacial behavior. Particular emphasis has been dedicated toward understanding how the hydrogen bond network of water responds to the pentane relative to the vapor interface and the sensitivity of the network to the individual pentane isomer and system temperature. Interfacial microsolvation of the immiscible solvents has been examined using graph theoretical methods that quantify the structure and dynamics of microsolvated species (both H2O in C5H12 and C5H12 in H2O). At room temperature, interfacial water at the pentane phase boundary is found to have markedly different organization and dynamics than at the vapor interface (as indicated by the hydrogen bond distributions and hydrogen bond persistence in solution). While the mesoscale interfacial properties (e.g. interfacial tension) are sensitive to the specific pentane isomer, the distribution and persistence of microsolvated species at the interface is nearly identical for both systems, irrespective of temperature (between 273 K and 298 K). This has important implications for understanding how properties defined by the interfacial organization are related to the underlying solvation reactions that drive formation of the phase boundary.

Tuning Interfacial Properties and Processes by Controlling the Rheology and Structure of Poly( N-isopropylacrylamide) Particles at Air/Water Interfaces.

PubMed

Maestro, Armando; Jones, Daniel; Sánchez de Rojas Candela, Carmen; Guzman, Eduardo; Duits, Michel H G; Cicuta, Pietro

2018-06-05

By combining controlled experiments on single interfaces with measurements on solitary bubbles and liquid foams, we show that poly( N-isopropylacrylamide) (PNIPAM) microgels assembled at air/water interfaces exhibit a solid to liquid transition changing the temperature, and that this is associated with the change in the interfacial microstructure of the PNIPAM particles around their volume phase transition temperature. We show that the solid behaves as a soft 2D colloidal glass, and that the existence of this solid/liquid transition offers an ideal platform to tune the permeability of air bubbles covered by PNIPAM and to control macroscopic foam properties such as drainage, stability, and foamability. PNIPAM particles on fluid interfaces allow new tunable materials, for example foam structures with variable mechanical properties upon small temperature changes.

Impact of Cavitation, High Shear Stress and Air/Liquid Interfaces on Protein Aggregation.

PubMed

Duerkop, Mark; Berger, Eva; Dürauer, Astrid; Jungbauer, Alois

2018-03-25

The reported impact of shear stress on protein aggregation has been contradictory. At high shear rates, the occurrence of cavitation or entrapment of air is reasonable and their effects possibly misattributed to shear stress. Nine different proteins (α-lactalbumin, two antibodies, fibroblast growth factor 2, granulocyte colony stimulating factor [GCSF], green fluorescence protein [GFP], hemoglobin, human serum albumin, and lysozyme) are tested for their aggregation behavior on vapor/liquid interfaces generated by cavitation and compared it to the isolated effects of high shear stress and air/liquid interfaces generated by foaming. Cavitation induced the aggregation of GCSF by +68.9%, hemoglobin +4%, and human serum albumin +2.9%, compared to a control, whereas the other proteins do not aggregate. The protein aggregation behaviors of the different proteins at air/liquid interfaces are similar to cavitation, but the effect is more pronounced. Air-liquid interface induced the aggregation of GCSF by +94.5%, hemoglobin +35.5%, and human serum albumin (HSA) +31.1%. The results indicate that the sensitivity of a certain protein toward cavitation is very similar to air/liquid-induced aggregation. Hence, hydroxyl radicals cannot be seen as the driving force for protein aggregation when cavitation occurs. Further, high shear rates of up to 10 8  s -1 do not affect any of the tested proteins. Therefore, also within this study generated extremely high isolated shear rates cannot be considered to harm structural integrity when processing proteins. © 2018 The Authors. Biotechnology Journal Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Smoothed particle hydrodynamics simulations of evaporation and explosive boiling of liquid drops in microgravity.

PubMed

Sigalotti, Leonardo Di G; Troconis, Jorge; Sira, Eloy; Peña-Polo, Franklin; Klapp, Jaime

2015-07-01

The rapid evaporation and explosive boiling of a van der Waals (vdW) liquid drop in microgravity is simulated numerically in two-space dimensions using the method of smoothed particle hydrodynamics. The numerical approach is fully adaptive and incorporates the effects of surface tension, latent heat, mass transfer across the interface, and liquid-vapor interface dynamics. Thermocapillary forces are modeled by coupling the hydrodynamics to a diffuse-interface description of the liquid-vapor interface. The models start from a nonequilibrium square-shaped liquid of varying density and temperature. For a fixed density, the drop temperature is increased gradually to predict the point separating normal boiling at subcritical heating from explosive boiling at the superheat limit for this vdW fluid. At subcritical heating, spontaneous evaporation produces stable drops floating in a vapor atmosphere, while at near-critical heating, a bubble is nucleated inside the drop, which then collapses upon itself, leaving a smaller equilibrated drop embedded in its own vapor. At the superheat limit, unstable bubble growth leads to either fragmentation or violent disruption of the liquid layer into small secondary drops, depending on the liquid density. At higher superheats, explosive boiling occurs for all densities. The experimentally observed wrinkling of the bubble surface driven by rapid evaporation followed by a Rayleigh-Taylor instability of the thin liquid layer and the linear growth of the bubble radius with time are reproduced by the simulations. The predicted superheat limit (T(s)≈0.96) is close to the theoretically derived value of T(s)=1 at zero ambient pressure for this vdW fluid.

Nonequilibrium Thermodynamics of Hydrate Growth on a Gas-Liquid Interface

NASA Astrophysics Data System (ADS)

Fu, Xiaojing; Cueto-Felgueroso, Luis; Juanes, Ruben

2018-04-01

We develop a continuum-scale phase-field model to study gas-liquid-hydrate systems far from thermodynamic equilibrium. We design a Gibbs free energy functional for methane-water mixtures that recovers the isobaric temperature-composition phase diagram under thermodynamic equilibrium conditions. The proposed free energy is incorporated into a phase-field model to study the dynamics of hydrate formation on a gas-liquid interface. We elucidate the role of initial aqueous concentration in determining the direction of hydrate growth at the interface, in agreement with experimental observations. Our model also reveals two stages of hydrate growth at an interface—controlled by a crossover in how methane is supplied from the gas and liquid phases—which could explain the persistence of gas conduits in hydrate-bearing sediments and other nonequilibrium phenomena commonly observed in natural methane hydrate systems.

Noninvasive method for determining the liquid level and density inside of a container

DOEpatents

Sinha, Dipen N.

2000-01-01

Noninvasive method for determining the liquid level and density inside of a container having arbitrary dimension and shape. By generating a flexural acoustic wave in the container shell and measuring the phase difference of the detected flexural wave from that of the originally generated wave a small distance from the generated wave, while moving the generation and detection means through the liquid/vapor interface, this interface can be detected. Both the wave generation and wave detection may be achieved by transducers on the surface of the container. A change in the phase difference over the outer surface of the vessel signifies that a liquid/vapor interface has been crossed, while the magnitude of the phase difference can be related to fluid density immediately opposite the measurement position on the surface of the vessel.

Approximating the nonlinear density dependence of electron transport coefficients and scattering rates across the gas-liquid interface

NASA Astrophysics Data System (ADS)

Garland, N. A.; Boyle, G. J.; Cocks, D. G.; White, R. D.

2018-02-01

This study reviews the neutral density dependence of electron transport in gases and liquids and develops a method to determine the nonlinear medium density dependence of electron transport coefficients and scattering rates required for modeling transport in the vicinity of gas-liquid interfaces. The method has its foundations in Blanc’s law for gas-mixtures and adapts the theory of Garland et al (2017 Plasma Sources Sci. Technol. 26) to extract electron transport data across the gas-liquid transition region using known data from the gas and liquid phases only. The method is systematically benchmarked against multi-term Boltzmann equation solutions for Percus-Yevick model liquids. Application to atomic liquids highlights the utility and accuracy of the derived method.

Spontaneous hybrids of graphene and carbon nanotube arrays at the liquid-gas interface for Li-ion battery anodes.

PubMed

Kim, Hyeri; Kim, Jongsoon; Jeong, Hee-Sung; Kim, Hyungsub; Lee, Hoyeon; Ha, Jae-Min; Choi, Sung-Min; Kim, Tae-Ho; Nah, Yoon-Chae; Shin, Tae Joo; Bang, Joona; Satija, Sushil K; Koo, Jaseung

2018-05-17

We demonstrate that hybrid structures of graphene and single-walled carbon nanotubes (SWNTs) are precisely controlled at the liquid-gas interface. The functionalized SWNT Langmuir monolayers anchor single-layer graphene nanosheets (GNSs) suspended in water via Coulomb interaction at the interface. This GNS/SWNT hybrid multilayer electrode can be a promising anode material for Li-ion batteries, offering high specific capacity, outstanding power capability, and excellent cyclability.

Liquid-Vapor Interface Configurations Investigated in Low Gravity

NASA Technical Reports Server (NTRS)

Concus, Paul; Finn, Robert; Weislogel, Mark M.

1998-01-01

The Interface Configuration Experiment (ICE) is part of a multifaceted study that is exploring the often striking behavior of liquid-vapor interfaces in low-gravity environments. Although the experiment was posed largely as a test of current mathematical theory, applications of the results should be manifold. In space almost every fluid system is affected, if not dominated, by capillarity (the effects of surface tension). As a result, knowledge of fluid interface behavior, in particular an equilibrium interface shape from which any analysis must begin, is fundamental--from the control of liquid fuels and oxygen in storage tanks to the design and development of inspace thermal systems, such as heat pipes and capillary pumped loops. ICE has increased, and should continue to increase, such knowledge as it probes the specific peculiarities of current theory upon which our present understanding rests. Several versions of ICE have been conducted in the drop towers at the NASA Lewis Research Center, on the space shuttles during the first and second United States Microgravity Laboratory missions (USML-1 and USML-2), and most recently aboard the Russian Mir space station. These studies focused on interfacial problems concerning the existence, uniqueness, configuration, stability, and flow characteristics of liquid-vapor interfaces. Results to date have clearly demonstrated the value of the present theory and the extent to which it can predict the behavior of capillary systems.

Measurement of liquid film in microchannels using a laser focus displacement meter

NASA Astrophysics Data System (ADS)

Hazuku, Tatsuya; Fukamachi, Norihiro; Takamasa, Tomoji; Hibiki, Takashi; Ishii, Mamoru

2005-06-01

This paper presents a new method for measuring the interfacial displacement of a liquid film in microchannels using a laser focus displacement meter (LFD). The purpose of the study is to clarify the effectiveness of the new method for obtaining detailed information concerning interfacial displacement, especially in the case of a thin liquid film, in microchannels and minichannels. To prevent the tube wall signal from disturbing that of the gas liquid interface, a fluorocarbon tube with a water box was used; the refraction index of this device is the same as that for water. With this method, accurate instantaneous measurements of the interfacial displacement of the liquid film were achieved. The error caused by refraction of the laser beam passing through the acrylic water box and fluorocarbon tube was estimated analytically and experimentally. The formulated analytical equation can estimate the real interface displacement by using the measured displacement in a fluorocarbon tube of 25 μm to 2.0 mm I.D. A preliminary test using fluorocarbon tubes of 1 mm and 2 mm I.D. showed that the corrected interface displacement calculated by the equation agreed with the real displacement to within a 1% margin of error. It was also confirmed that the LFD in the system could measure a liquid film of 0.25 μm at the thinnest. We made simultaneous measurements of the interface in fluorocarbon tubes of 0.5 mm and 1 mm I.D. using the LFD and a high-speed video camera with a microscope. These showed that the LFD could measure the interface of a liquid film with high spatial and temporal resolution during annular, slug, and piston flow regimes. The data also clarified the existence of a thin liquid film of less than 1 μm in thickness in the slug and annular flow regimes.

Low Gravity venting of Refrigerant 11

NASA Technical Reports Server (NTRS)

Labus, T. L.; Aydelott, J. C.; Lacovic, R. F.

1972-01-01

An experimental investigation was conducted in a five-second zero gravity facility to examine the effects of venting initially saturated Refrigerant 11 from a cylindrical container (15-cm diameter) under reduced gravitational conditions. The system Bond numbers studied were 0 (weightlessness), 9 and 63; the liquid exhibited a nearly zero-degree contact angle on the container surface. During the venting process, both liquid-vapor interface and liquid bulk vaporization occurred. The temperature of the liquid in the immediate vicinity of the liquid-vapor interface was found to decrease during venting, while the liquid bulk temperature remained constant. Qualitative observations of the effects of system acceleration, vent rate, and vapor volume presented. Quantitative information concerning the ullage pressure decay during low gravity venting is also included.

Improving the Molecular Ion Signal Intensity for In Situ Liquid SIMS Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Yufan; Yao, Juan; Ding, Yuanzhao

In situ liquid secondary ion mass spectrometry (SIMS) enabled by system for analysis at the liquid vacuum interface (SALVI) has proven to be a promising new tool to provide molecular information at solid–liquid and liquid–vacuum interfaces. However, the initial data showed that useful signals in positive ion spectra are too weak to be meaningful in most cases. In addition, it is difficult to obtain strong negative molecular ion signals when m/z>200. These two drawbacks have been the biggest obstacle towards practical use of this new analytical approach. In this study, we report that strong and reliable positive and negative molecularmore » signals are achievable after optimizing the SIMS experimental conditions. Four model systems, including a 1,8-diazabicycloundec-7-ene (DBU)-base switchable ionic liquid, a live Shewanella oneidensis biofilm, a hydrated mammalian epithelia cell, and an electrolyte popularly used in Li ion batteries were studied. A signal enhancement of about two orders of magnitude was obtained in comparison with non-optimized conditions. Therefore, molecular ion signal intensity has become very acceptable to use for in situ liquid SIMS to study solid–liquid and liquid–vacuum interfaces.« less

Interfacial Dynamics of Condensing Vapor Bubbles in an Ultrasonic Acoustic Field

NASA Astrophysics Data System (ADS)

Boziuk, Thomas; Smith, Marc; Glezer, Ari

2016-11-01

Enhancement of vapor condensation in quiescent subcooled liquid using ultrasonic actuation is investigated experimentally. The vapor bubbles are formed by direct injection from a pressurized steam reservoir through nozzles of varying characteristic diameters, and are advected within an acoustic field of programmable intensity. While kHz-range acoustic actuation typically couples to capillary instability of the vapor-liquid interface, ultrasonic (MHz-range) actuation leads to the formation of a liquid spout that penetrates into the vapor bubble and significantly increases its surface area and therefore condensation rate. Focusing of the ultrasonic beam along the spout leads to ejection of small-scale droplets from that are propelled towards the vapor liquid interface and result in localized acceleration of the condensation. High-speed video of Schlieren images is used to investigate the effects of the ultrasonic actuation on the thermal boundary layer on the liquid side of the vapor-liquid interface and its effect on the condensation rate, and the liquid motion during condensation is investigated using high-magnification PIV measurements. High-speed image processing is used to assess the effect of the actuation on the dynamics and temporal variation in characteristic scale (and condensation rate) of the vapor bubbles.

Vapor condensation on liquid surface due to laminar jet-induced mixing: The effects of system parameters

NASA Technical Reports Server (NTRS)

Lin, Chin-Shun; Hasan, Mohammad M.

1989-01-01

The effects of system parameters on the interface condensation rate in a laminar jet induced mixing tank are numerically studied. The physical system consists of a partially filled cylindrical tank with a slightly subcooled jet discharged from the center of the tank bottom toward the liquid-vapor interface which is at a saturation temperature corresponding to the constant tank pressure. Liquid is also withdrawn from the outer part of the tank bottom to maintain the constant liquid level. The jet velocity is selected to be low enough such that the free surface is approximately flat. The effect of vapor superheat is assumed to be negligible. Therefore, the interface condensation rate can be determined from the resulting temperature field in the liquid region alone. The nondimensional form of the steady state conservation equations are solved by a finite difference method for various system parameters including liquid height to tank diameter ratio, tank to jet diameter ratio, liquid inflow to outflow area ratio, and a heat leak parameter which characterizes the uniform wall heat flux. Detailed analyses based on the numerical solutions are performed and simplified equations are suggested for the prediction of condensation rate.

Lagrangian Modeling of Evaporating Sprays at Diesel Engine Conditions: Effects of Multi-Hole Injector Nozzles With JP-8 Surrogates

DTIC Science & Technology

2014-05-01

solver to treat the spray process. An Adaptive Mesh Refinement (AMR) and fixed embedding technique is employed to capture the gas - liquid interface with...Adaptive Mesh Refinement (AMR) and fixed embedding technique is employed to capture the gas - liquid interface with high fidelity while keeping the cell...in single and multi-hole nozzle configurations. The models were added to the present CONVERGE liquid fuel database and validated extensively

Surfactant Effect on the Average Flow Generation Near Curved Interface

NASA Astrophysics Data System (ADS)

Klimenko, Lyudmila; Lyubimov, Dmitry

2018-02-01

The present work is devoted to the average flow generation near curved interface with a surfactant adsorbed on the surface layer. The investigation was carried out for a liquid drop embedded in a viscous liquid with a different density. The liquid flows inside and outside the drop are generated by small amplitude and high frequency vibrations. Surfactant exchange between the drop surface and the surrounding liquid is limited by the process of adsorption-desorption. It was assumed that the surfactant is soluble in the surrounding liquid, but not soluble in the liquid drop. Surrounding liquid and the liquid in the drop are considered incompressible. Normal and shear viscous stresses balance at the interface is performed under the condition that the film thickness of the adsorbed surfactant is negligible. The problem is solved under assumption that the shape of the drop in the presence of adsorbed surfactant remains spherical symmetry. The effective boundary conditions for the tangential velocity jump and shear stress jump, describing the above generation have been obtained by matched asymptotic expansions method. The conditions under which the drop surface can be considered as a quasi-solid are determined. It is shown that in the case of the significant effect of surfactant on the surface tension, the dominant mechanism for the generation is the Schlichting mechanisms under vibrations.

Optical-to-optical interface device

NASA Technical Reports Server (NTRS)

Jacobson, A. D.; Bleha, W. P.; Miller, L.; Grinberg, J.; Fraas, L.; Margerum, D.

1975-01-01

An investigation was conducted to develop an optical-to-optical interface device capable of performing real-time incoherent-to-incoherent optical image conversion. The photoactivated liquid crystal light valve developed earlier represented a prototype liquid crystal light valve device capable of performing these functions. A device was developed which had high performance and extended lifetime.

Growth of human bronchial epithelial cells at an air-liquid interface alters the response to particle exposure

EPA Science Inventory

Abstract: We tested the hypothesis that relative to submerged cells, airway epithelial cells grown at an air-liquid interface would have an altered response to particle exposure. RNA for IL-8, IL-6, heme oxygenase 1 and cyclooxygenase 2 increased following exposure of submer...

25 CFR 547.8 - What are the minimum technical software standards applicable to Class II gaming systems?

Code of Federal Regulations, 2012 CFR

2012-04-01

... OF CLASS II GAMES § 547.8 What are the minimum technical software standards applicable to Class II... of Class II games. (a) Player interface displays. (1) If not otherwise provided to the player, the player interface shall display the following: (i) The purchase or wager amount; (ii) Game results; and...

25 CFR 547.8 - What are the minimum technical software standards applicable to Class II gaming systems?

Code of Federal Regulations, 2011 CFR

2011-04-01

... OF CLASS II GAMES § 547.8 What are the minimum technical software standards applicable to Class II... of Class II games. (a) Player interface displays. (1) If not otherwise provided to the player, the player interface shall display the following: (i) The purchase or wager amount; (ii) Game results; and...

25 CFR 547.8 - What are the minimum technical software standards applicable to Class II gaming systems?

Code of Federal Regulations, 2010 CFR

2010-04-01

... OF CLASS II GAMES § 547.8 What are the minimum technical software standards applicable to Class II... of Class II games. (a) Player interface displays. (1) If not otherwise provided to the player, the player interface shall display the following: (i) The purchase or wager amount; (ii) Game results; and...

Effect of Liquid Surface Turbulent Motion on the Vapor Condensation in a Mixing Tank

NASA Technical Reports Server (NTRS)

Lin, C. S.; Hasan, M. M.

1991-01-01

The effect of liquid surface motion on the vapor condensation in a tank mixed by an axial turbulent jet is numerically investigated. The average value (over the interface area) of the root-mean-squared (rms) turbulent velocity at the interface is shown to be linearly increasing with decreasing liquid height and increasing jet diameter for a given tank size. The average rms turbulent velocity is incorporated in Brown et al. (1990) condensation correlation to predict the condensation of vapor on a liquid surface. The results are in good agreement with available condensation data.

Molecular dynamics of the water liquid-vapor interface

NASA Technical Reports Server (NTRS)

Wilson, M. A.; Pohorille, A.; Pratt, L. R.; MacElroy, R. D. (Principal Investigator)

1987-01-01

The results of molecular dynamics calculations on the equilibrium interface between liquid water and its vapor at 325 K are presented. For the TIP4P model of water intermolecular pair potentials, the average surface dipole density points from the vapor to the liquid. The most common orientations of water molecules have the C2 nu molecular axis roughly parallel to the interface. The distributions are quite broad and therefore compatible with the intermolecular correlations characteristic of bulk liquid water. All near-neighbor pairs in the outermost interfacial layers are hydrogen bonded according to the common definition adopted here. The orientational preferences of water molecules near a free surface differ from those near rigidly planar walls which can be interpreted in terms of patterns found in hexagonal ice 1. The mean electric field in the interfacial region is parallel to the mean polarization which indicates that attention cannot be limited to dipolar charge distributions in macroscopic descriptions of the electrical properties of this interface. The value of the surface tension obtained is 132 +/- 46 dyn/cm, significantly different from the value for experimental water of 68 dyn/cm at 325 K.

Method and apparatus for operating an improved thermocline storage unit

DOEpatents

Copeland, R.J.

1982-09-30

A method and apparatus for operating a thermocline storage unit in which an insulated barrier member is provided substantially at the interface region between the hot and cold liquids in the storage tank. The barrier member physically and thermally separates the hot and cold liquids substantially preventing any diffusing or mixing between them and substantially preventing any heat transfer there between. The barrier member follows the rise and fall of the interface region between the liquids as the tank is charged and discharged. Two methods of maintaining it in the interface region are disclosed. With the structure and operation of the present invention and in particular the significant reduction in diffusing or mixing between the hot and cold liquids as well as the significant reduction in the thermal heat transfer between them, the performance of the storage tank is improved. More specifically, the stability of the interface region or thermocline is enhanced and the thickness of the thermocline is reduced producing a corresponding increase in the steepness of the temperature gradient across the thermocline and a more efficiently operating thermocline storage unit.

Method and apparatus for operating an improved thermocline storage unit

DOEpatents

Copeland, Robert J.

1985-01-01

A method and apparatus for operating a thermocline storage unit in which an insulated barrier member is provided substantially at the interface region between the hot and cold liquids in the storage tank. The barrier member physically and thermally separates the hot and cold liquids substantially preventing any diffusing or mixing between them and substantially preventing any heat transfer therebetween. The barrier member follows the rise and fall of the interface region between the liquids as the tank is charged and discharged. Two methods of maintaining it in the interface region are disclosed. With the structure and operation of the present invention and in particular the significant reduction in diffusing or mixing between the hot and cold liquids as well as the significant reduction in the thermal heat transfer between them, the performance of the storage tank is improved. More specifically, the stability of the interface region or thermocline is enhanced and the thickness of the thermocline is reduced producing a corresponding increase in the steepness of the temperature gradient across the thermocline and a more efficiently operating thermocline storage unit.

Thermal transport study across interface “nanostructured solid surface / fluid” by photoacoustic technique

NASA Astrophysics Data System (ADS)

Voitenko, K.; Isaiev, M.; Pastushenko, A.; Andrusenko, D.; Kuzmich, A.; Lysenko, V.; Burbelo, R.

2017-01-01

In the paper the experimental study of heat transport across the interface “porous silicon/liquid” by photoacoustic technique is reported. Two cases with and without liquid covering of porous silicon surface were considered. Thermal perturbations were excited at the surface of porous silicon as a result of absorption of the light with modulated intensity. The resulting thermal-elastic stresses arising in the system were registered with piezoelectric transducer. The amplitude-frequency dependencies of the voltage on the piezoelectric electrodes were measured. The presence of the liquid film leads to decreasing of the amplitude of photoacoustic signal as a result of the thermal energy evacuation from the porous silicon into the liquid. The experimental dependencies were fitted with the results of simulation that takes into account heat fluxes separation at the porous silicon/liquid interface. With the presented method one can precisely measure heat fluxes transferred from the solid into contacting fluid. Moreover, the presented approach can be easily adopted for the thermal conductivity study of the different nanofluids as well as thermal resistance at the interface nanostructured solid/fluid.

Simulating compressible-incompressible two-phase flows

NASA Astrophysics Data System (ADS)

Denner, Fabian; van Wachem, Berend

2017-11-01

Simulating compressible gas-liquid flows, e.g. air-water flows, presents considerable numerical issues and requires substantial computational resources, particularly because of the stiff equation of state for the liquid and the different Mach number regimes. Treating the liquid phase (low Mach number) as incompressible, yet concurrently considering the gas phase (high Mach number) as compressible, can improve the computational performance of such simulations significantly without sacrificing important physical mechanisms. A pressure-based algorithm for the simulation of two-phase flows is presented, in which a compressible and an incompressible fluid are separated by a sharp interface. The algorithm is based on a coupled finite-volume framework, discretised in conservative form, with a compressive VOF method to represent the interface. The bulk phases are coupled via a novel acoustically-conservative interface discretisation method that retains the acoustic properties of the compressible phase and does not require a Riemann solver. Representative test cases are presented to scrutinize the proposed algorithm, including the reflection of acoustic waves at the compressible-incompressible interface, shock-drop interaction and gas-liquid flows with surface tension. Financial support from the EPSRC (Grant EP/M021556/1) is gratefully acknowledged.

Dual analyzer system for surface analysis dedicated for angle-resolved photoelectron spectroscopy at liquid surfaces and interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niedermaier, Inga; Kolbeck, Claudia; Steinrück, Hans-Peter

The investigation of liquid surfaces and interfaces with the powerful toolbox of ultra-high vacuum (UHV)-based surface science techniques generally has to overcome the issue of liquid evaporation within the vacuum system. In the last decade, however, new classes of liquids with negligible vapor pressure at room temperature—in particular, ionic liquids (ILs)—have emerged for surface science studies. It has been demonstrated that particularly angle-resolved X-ray Photoelectron Spectroscopy (ARXPS) allows for investigating phenomena that occur at gas-liquid and liquid-solid interfaces on the molecular level. The results are not only relevant for IL systems but also for liquids in general. In all ofmore » these previous ARXPS studies, the sample holder had to be tilted in order to change the polar detection angle of emitted photoelectrons, which restricted the liquid systems to very thin viscous IL films coating a flat solid support. We now report on the concept and realization of a new and unique laboratory “Dual Analyzer System for Surface Analysis (DASSA)” which enables fast ARXPS, UV photoelectron spectroscopy, imaging XPS, and low-energy ion scattering at the horizontal surface plane of macroscopically thick non-volatile liquid samples. It comprises a UHV chamber equipped with two electron analyzers mounted for simultaneous measurements in 0° and 80° emission relative to the surface normal. The performance of DASSA on a first macroscopic liquid system will be demonstrated.« less

Numerical modeling of spray combustion with an advanced VOF method

NASA Technical Reports Server (NTRS)

Chen, Yen-Sen; Shang, Huan-Min; Shih, Ming-Hsin; Liaw, Paul

1995-01-01

This paper summarizes the technical development and validation of a multiphase computational fluid dynamics (CFD) numerical method using the volume-of-fluid (VOF) model and a Lagrangian tracking model which can be employed to analyze general multiphase flow problems with free surface mechanism. The gas-liquid interface mass, momentum and energy conservation relationships are modeled by continuum surface mechanisms. A new solution method is developed such that the present VOF model can be applied for all-speed flow regimes. The objectives of the present study are to develop and verify the fractional volume-of-fluid cell partitioning approach into a predictor-corrector algorithm and to demonstrate the effectiveness of the present approach by simulating benchmark problems including laminar impinging jets, shear coaxial jet atomization and shear coaxial spray combustion flows.

Interface for the rapid analysis of liquid samples by accelerator mass spectrometry

DOEpatents

Turteltaub, Kenneth; Ognibene, Ted; Thomas, Avi; Daley, Paul F; Salazar Quintero, Gary A; Bench, Graham

2014-02-04

An interface for the analysis of liquid sample having carbon content by an accelerator mass spectrometer including a wire, defects on the wire, a system for moving the wire, a droplet maker for producing droplets of the liquid sample and placing the droplets of the liquid sample on the wire in the defects, a system that converts the carbon content of the droplets of the liquid sample to carbon dioxide gas in a helium stream, and a gas-accepting ion source connected to the accelerator mass spectrometer that receives the carbon dioxide gas of the sample in a helium stream and introduces the carbon dioxide gas of the sample into the accelerator mass spectrometer.

Hexagonal bubble formation and nucleation in sodium chloride solution

NASA Astrophysics Data System (ADS)

Wang, Lifen; Liu, Lei; Mohsin, Ali; Wen, Jianguo; Gu, Gong; Miller, Dean

The bubble is formed frequently at a solid-liquid interface when the surface of the solid or liquid has a tendency of accumulating molecular species due to unbalanced surface hydrophobicity attraction. Morphology and shape of the bubble are thought to be associated with the Laplace pressure that spherical-cap-shaped object are commonly observed. Dynamic surface nanobubble formation and nucleation in the controlled system have been not fully investigated due to the direct visualization challenge in liquid systems. Here, utilizing in situ TEM, dynamic formation and collapse of spherical-shaped nanobubbles were observed at the water-graphene interface, while hexagonal nanobubbles grew and merged with each other at water-crystalline sodium chloride interface. Our finding demonstrates that different hydrophobic-hydrophilic interaction systems give rise to the varied morphology of surface nanobubble, leading to the fundamental understanding of the interface-interaction-governed law on the formation of surface nanobubble.

The isoelectric point/point-of zero-charge of interfaces formed by aqueous solutions and nonpolar solids, liquids, and gases.

PubMed

Healy, Thomas W; Fuerstenau, Douglas W

2007-05-01

From our previous work on the role of the electrostatic field strength in controlling the pH of the iso-electric point (iep)/point-of-zero-charge (pzc) of polar solids we have extended the analysis to predict that the pH of the iep/pzc of a nonpolar solid, liquid or gas-aqueous interface should occur at pH 1.0-3.0, dependent on the value assigned to water molecules or clusters at the interface. Consideration of a wide range of experimental results covering nonpolar solids such as molybdenite, stibnite, paraffin, etc. as well as hydrocarbon liquids such as xylene, decalin, and long chain (>C8) alkane oils, as well as nitrogen and hydrogen gases, all in various simple 1:1 electrolyte solutions confirm the general validity of the result. We further consider various models of the origin of the charge on nonpolar material-water interfaces.

Processing eutectics in space

NASA Technical Reports Server (NTRS)

Douglas, F. C.; Galasso, F. S.

1974-01-01

Experimental work is reported which was directed toward obtaining interface shape control while a numerical thermal analysis program was being made operational. An experimental system was developed in which the solid-liquid interface in a directionally solidified aluminum-nickel eutectic could be made either concave to the melt or convex to the melt. This experimental system provides control over the solid-liquid interface shape and can be used to study the effect of such control on the microstructure. The SINDA thermal analysis program, obtained from Marshall Space Flight Center, was used to evaluate experimental directional solidification systems for the aluminum-nickel and the aluminum-copper eutectics. This program was applied to a three-dimensional ingot, and was used to calculate the thermal profiles in axisymmetric heat flow. The results show that solid-liquid interface shape control can be attained with physically realizable thermal configurations and the magnitudes of the required thermal inputs were indicated.

Microfluidics on liquid handling stations (μF-on-LHS): an industry compatible chip interface between microfluidics and automated liquid handling stations.

PubMed

Waldbaur, Ansgar; Kittelmann, Jörg; Radtke, Carsten P; Hubbuch, Jürgen; Rapp, Bastian E

2013-06-21

We describe a generic microfluidic interface design that allows the connection of microfluidic chips to established industrial liquid handling stations (LHS). A molding tool has been designed that allows fabrication of low-cost disposable polydimethylsiloxane (PDMS) chips with interfaces that provide convenient and reversible connection of the microfluidic chip to industrial LHS. The concept allows complete freedom of design for the microfluidic chip itself. In this setup all peripheral fluidic components (such as valves and pumps) usually required for microfluidic experiments are provided by the LHS. Experiments (including readout) can be carried out fully automated using the hardware and software provided by LHS manufacturer. Our approach uses a chip interface that is compatible with widely used and industrially established LHS which is a significant advancement towards near-industrial experimental design in microfluidics and will greatly facilitate the acceptance and translation of microfluidics technology in industry.

Simplified conditions holding at the gas-liquid interface during evaporation

NASA Astrophysics Data System (ADS)

Morris, S. J. S.

2017-11-01

We show that on the gas side of the interface between a pure liquid and a binary mixture of its vapour with an insoluble gas, the normal derivative of vapour partial pressure pv satisfies ∂pv/∂n +αc/2 πpD (P -pv) (p -pv) = 0 . Constants α, c, D denote the dimensionless accommodation coefficient, a molecular speed and the diffusivity. Provided the continuum approximation holds within the gas, and α = O(1) , this boundary condition implies that evaporation can take one of two forms. (a) If the coexistence pressure P evaluated at the interface is less than the constant total gas pressure p, liquid at the interface is in local thermodynamic equilibrium with its vapour, and the evaporation rate is determined by diffusion through the gas. (b) Conversely, if P > p , gas at the interface consists of pure vapour, and the evaporation rate is determined by processes within the liquid. In the Wayner theory of the heated evaporating meniscus, such as that in a heat pipe, case (b) is assumed. As an application of our result, we show that some of the published experiments intended to test the Wayner theory instead operate under conditions in which case (a) holds. As a result, they do not perform the test intended.

Numerical and Experimental Investigation of Stratified Gas-Liquid Two-Phase Flow in Horizontal Circular Pipes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faccini, J.L.H.; Sampaio, P.A.B. de; Su, J.

This paper reports numerical and experimental investigation of stratified gas-liquid two-phase flow in horizontal circular pipes. The Reynolds averaged Navier Stokes equations (RANS) with the k-{omega} model for a fully developed stratified gas-liquid two-phase flow are solved by using the finite element method. A smooth and horizontal interface surface is assumed without considering the interfacial waves. The continuity of the shear stress across the interface is enforced with the continuity of the velocity being automatically satisfied by the variational formulation. For each given interface position and longitudinal pressure gradient, an inner iteration loop runs to solve the nonlinear equations. Themore » Newton-Raphson scheme is used to solve the transcendental equations by an outer iteration to determine the interface position and pressure gradient for a given pair of volumetric flow rates. The interface position in a 51.2 mm ID circular pipe was measured experimentally by the ultrasonic pulse-echo technique. The numerical results were also compared with experimental results in a 21 mm ID circular pipe reported by Masala [1]. The good agreement between the numerical and experimental results indicates that the k-{omega} model can be applied for the numerical simulation of stratified gas-liquid two-phase flow. (authors)« less

Effect of the Thermocouple on Measuring the Temperature Discontinuity at a Liquid-Vapor Interface.

PubMed

Kazemi, Mohammad Amin; Nobes, David S; Elliott, Janet A W

2017-07-18

The coupled heat and mass transfer that occurs in evaporation is of interest in a large number of fields such as evaporative cooling, distillation, drying, coating, printing, crystallization, welding, atmospheric processes, and pool fires. The temperature jump that occurs at an evaporating interface is of central importance to understanding this complex process. Over the past three decades, thermocouples have been widely used to measure the interfacial temperature jumps at a liquid-vapor interface during evaporation. However, the reliability of these measurements has not been investigated so far. In this study, a numerical simulation of a thermocouple when it measures the interfacial temperatures at a liquid-vapor interface is conducted to understand the possible effects of the thermocouple on the measured temperature and features in the temperature profile. The differential equations of heat transfer in the solid and fluids as well as the momentum transfer in the fluids are coupled together and solved numerically subject to appropriate boundary conditions between the solid and fluids. The results of the numerical simulation showed that while thermocouples can measure the interfacial temperatures in the liquid correctly, they fail to read the actual interfacial temperatures in the vapor. As the results of our numerical study suggest, the temperature jumps at a liquid-vapor interface measured experimentally by using a thermocouple are larger than what really exists at the interface. For a typical experimental study of evaporation of water at low pressure, it was found that the temperature jumps measured by a thermocouple are overestimated by almost 50%. However, the revised temperature jumps are still in agreement with the statistical rate theory of interfacial transport. As well as addressing the specific application of the liquid-vapor temperature jump, this paper provides significant insight into the role that heat transfer plays in the operation of thermocouples in general.

Understanding the breakdown of classic two-phase theory and spray atomization at engine-relevant conditions

NASA Astrophysics Data System (ADS)

Dahms, Rainer N.

2016-04-01

A generalized framework for multi-component liquid injections is presented to understand and predict the breakdown of classic two-phase theory and spray atomization at engine-relevant conditions. The analysis focuses on the thermodynamic structure and the immiscibility state of representative gas-liquid interfaces. The most modern form of Helmholtz energy mixture state equation is utilized which exhibits a unique and physically consistent behavior over the entire two-phase regime of fluid densities. It is combined with generalized models for non-linear gradient theory and for liquid injections to quantify multi-component two-phase interface structures in global thermal equilibrium. Then, the Helmholtz free energy is minimized which determines the interfacial species distribution as a consequence. This minimal free energy state is demonstrated to validate the underlying assumptions of classic two-phase theory and spray atomization. However, under certain engine-relevant conditions for which corroborating experimental data are presented, this requirement for interfacial thermal equilibrium becomes unsustainable. A rigorously derived probability density function quantifies the ability of the interface to develop internal spatial temperature gradients in the presence of significant temperature differences between injected liquid and ambient gas. Then, the interface can no longer be viewed as an isolated system at minimal free energy. Instead, the interfacial dynamics become intimately connected to those of the separated homogeneous phases. Hence, the interface transitions toward a state in local equilibrium whereupon it becomes a dense-fluid mixing layer. A new conceptual view of a transitional liquid injection process emerges from a transition time scale analysis. Close to the nozzle exit, the two-phase interface still remains largely intact and more classic two-phase processes prevail as a consequence. Further downstream, however, the transition to dense-fluid mixing generally occurs before the liquid length is reached. The significance of the presented modeling expressions is established by a direct comparison to a reduced model, which utilizes widely applied approximations but fundamentally fails to capture the physical complexity discussed in this paper.

A Ghost Fluid/Level Set Method for boiling flows and liquid evaporation: Application to the Leidenfrost effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rueda Villegas, Lucia; Alis, Romain; Lepilliez, Mathieu

2016-07-01

The development of numerical methods for the direct numerical simulation of two-phase flows with phase change, in the framework of interface capturing or interface tracking methods, is the main topic of this study. We propose a novel numerical method, which allows dealing with both evaporation and boiling at the interface between a liquid and a gas. Indeed, in some specific situations involving very heterogeneous thermodynamic conditions at the interface, the distinction between boiling and evaporation is not always possible. For instance, it can occur for a Leidenfrost droplet; a water drop levitating above a hot plate whose temperature is muchmore » higher than the boiling temperature. In this case, boiling occurs in the film of saturated vapor which is entrapped between the bottom of the drop and the plate, whereas the top of the water droplet evaporates in contact of ambient air. The situation can also be ambiguous for a superheated droplet or at the contact line between a liquid and a hot wall whose temperature is higher than the saturation temperature of the liquid. In these situations, the interface temperature can locally reach the saturation temperature (boiling point), for instance near a contact line, and be cooler in other places. Thus, boiling and evaporation can occur simultaneously on different regions of the same liquid interface or occur successively at different times of the history of an evaporating droplet. Standard numerical methods are not able to perform computations in these transient regimes, therefore, we propose in this paper a novel numerical method to achieve this challenging task. Finally, we present several accuracy validations against theoretical solutions and experimental results to strengthen the relevance of this new method.« less

Characterizing water-metal interfaces and machine learning potential energy surfaces

NASA Astrophysics Data System (ADS)

Ryczko, Kevin

In this thesis, we first discuss the fundamentals of ab initio electronic structure theory and density functional theory (DFT). We also discuss statistics related to computing thermodynamic averages of molecular dynamics (MD). We then use this theory to analyze and compare the structural, dynamical, and electronic properties of liquid water next to prototypical metals including platinum, graphite, and graphene. Our results are built on Born-Oppenheimer molecular dynamics (BOMD) generated using density functional theory (DFT) which explicitly include van der Waals (vdW) interactions within a first principles approach. All calculations reported use large simulation cells, allowing for an accurate treatment of the water-electrode interfaces. We have included vdW interactions through the use of the optB86b-vdW exchange correlation functional. Comparisons with the Perdew-Burke-Ernzerhof (PBE) exchange correlation functional are also shown. We find an initial peak, due to chemisorption, in the density profile of the liquid water-Pt interface not seen in the liquid water-graphite interface, liquid watergraphene interface, nor interfaces studied previously. To further investigate this chemisorption peak, we also report differences in the electronic structure of single water molecules on both Pt and graphite surfaces. We find that a covalent bond forms between the single water molecule and the platinum surface, but not between the single water molecule and the graphite surface. We also discuss the effects that defects and dopants in the graphite and graphene surfaces have on the structure and dynamics of liquid water. Lastly, we introduce artificial neural networks (ANNs), and demonstrate how they can be used to machine learn electronic structure calculations. As a proof of principle, we show the success of an ANN potential energy surfaces for a dimer molecule with a Lennard-Jones potential.

On the origin of the electrostatic potential difference at a liquid-vacuum interface.

PubMed

Harder, Edward; Roux, Benoît

2008-12-21

The microscopic origin of the interface potential calculated from computer simulations is elucidated by considering a simple model of molecules near an interface. The model posits that molecules are isotropically oriented and their charge density is Gaussian distributed. Molecules that have a charge density that is more negative toward their interior tend to give rise to a negative interface potential relative to the gaseous phase, while charge densities more positive toward their interior give rise to a positive interface potential. The interface potential for the model is compared to the interface potential computed from molecular dynamics simulations of the nonpolar vacuum-methane system and the polar vacuum-water interface system. The computed vacuum-methane interface potential from a molecular dynamics simulation (-220 mV) is captured with quantitative precision by the model. For the vacuum-water interface system, the model predicts a potential of -400 mV compared to -510 mV, calculated from a molecular dynamics simulation. The physical implications of this isotropic contribution to the interface potential is examined using the example of ion solvation in liquid methane.

A new model for fluid velocity slip on a solid surface.

PubMed

Shu, Jian-Jun; Teo, Ji Bin Melvin; Chan, Weng Kong

2016-10-12

A general adsorption model is developed to describe the interactions between near-wall fluid molecules and solid surfaces. This model serves as a framework for the theoretical modelling of boundary slip phenomena. Based on this adsorption model, a new general model for the slip velocity of fluids on solid surfaces is introduced. The slip boundary condition at a fluid-solid interface has hitherto been considered separately for gases and liquids. In this paper, we show that the slip velocity in both gases and liquids may originate from dynamical adsorption processes at the interface. A unified analytical model that is valid for both gas-solid and liquid-solid slip boundary conditions is proposed based on surface science theory. The corroboration with the experimental data extracted from the literature shows that the proposed model provides an improved prediction compared to existing analytical models for gases at higher shear rates and close agreement for liquid-solid interfaces in general.

Interface mobility and the liquid-glass transition in a one-component system described by an embedded atom method potential

NASA Astrophysics Data System (ADS)

Mendelev, M. I.; Schmalian, J.; Wang, C. Z.; Morris, J. R.; Ho, K. M.

2006-09-01

We present molecular dynamics (MD) studies of the liquid structure, thermodynamics, and dynamics in a one-component system described by the Ercolessi-Adams embedded atom method potential for Al. We find two distinct noncrystalline phases in this system. One of them is a liquid phase and the second phase has similar structure but different equation of state. Moreover, this phase has qualitatively different dynamics than that in the liquid phase. The transitions between these two noncrystalline phases can be seen during MD simulation. The hysteresis in this transition suggests that this is a first-order transition. This conclusion is strongly supported by simulations of the two phases that demonstrate that these phases may coexist with a well-defined interface. We find the coexistent temperature and the interface mobility. Finally, we discuss how these results can be explained using modern models of vitrification.

Effect of a weak transverse magnetic field on the microstructure in directionally solidified peritectic alloys

PubMed Central

Li, Xi; Lu, Zhenyuan; Fautrelle, Yves; Gagnoud, Annie; Moreau, Rene; Ren, Zhongming

2016-01-01

Effect of a weak transverse magnetic field on the microstructures in directionally solidified Fe-Ni and Pb-Bi peritectic alloys has been investigated experimentally. The results indicate that the magnetic field can induce the formation of banded and island-like structures and refine the primary phase in peritectic alloys. The above results are enhanced with increasing magnetic field. Furthermore, electron probe micro analyzer (EPMA) analysis reveals that the magnetic field increases the Ni solute content on one side and enhances the solid solubility in the primary phase in the Fe-Ni alloy. The thermoelectric (TE) power difference at the liquid/solid interface of the Pb-Bi peritectic alloy is measured in situ, and the results show that a TE power difference exists at the liquid/solid interface. 3 D numerical simulations for the TE magnetic convection in the liquid are performed, and the results show that a unidirectional TE magnetic convection forms in the liquid near the liquid/solid interface during directional solidification under a transverse magnetic field and that the amplitude of the TE magnetic convection at different scales is different. The TE magnetic convections on the macroscopic interface and the cell/dendrite scales are responsible for the modification of microstructures during directional solidification under a magnetic field. PMID:27886265

Cavitation Inception Scale Effects. 1. Nuclei Distributions in Natural Waters. 2. Cavitation Inception in a Turbulent Shear Flow.

DTIC Science & Technology

1987-05-01

ratio of specific heats for the gas and an adiabatic bubble pressure- volume relation has been assumed (Plesset & Prosperetti 1977). When viscosity...pressure because of surface tension at the gas -liquid interface , so the gas is stabilized in the crevice and will not dissolve into the liquid. The concave... interface toward the gas is estab- lished by the hydrophobic nature of the particle, and results in surface tension acting to oppose the liquid

Surface charge-induced EDL interaction on the contact angle of surface nanobubbles.

PubMed

Jing, Dalei; Li, Dayong; Pan, Yunlu; Bhushan, Bharat

2016-11-01

The contact angle (CA) of surface nanobubbles is believed to affect the stability of nanobubbles and fluid drag in micro/nanofluidic systems. The CA of nanobubbles is dependent on size and is believed to be affected by the surface charge-induced electrical double layer (EDL). However, neither of these of attributes are well understood. In this paper, by introducing an EDL-induced electrostatic wetting tension, a theoretical model is first established to study the effect of EDLs formed near the solid-liquid interface and the liquid-nanobubble interface on the gas phase CA of nanobubbles. The size-dependence of this EDL interaction is studied as well. Next, by using atomic force microscopy (AFM), the effect of the EDL on nanobubbles' gas phase CA is studied with variable electrical potential at the solid-liquid interface, which is adjusted by an applied voltage. Both the theoretical and the experimental results show that the EDLs formed near the solid-liquid interface and the liquid-nanobubble interface lead to a reduction of gas phase CA of the surface nanobubbles because of an electrostatic wetting tension on the nanobubble due to the attractive electrostatic interaction between the liquid and nanobubble within the EDL, which is in the nanobubbles' outward direction. An EDL with a larger zeta potential magnitude leads to a larger gas phase CA reduction. Furthermore, the effect of EDL on the nanobubbles' gas phase CA shows a significant size-dependence considering the size dependence of the electrostatic wetting tension. The gas phase CA reduction due to the EDL decreases with increasing nanobubble height and increases with the nanobubble's increasing curvature radius, indicating that a surface charge-induced EDL could possibly explain the size dependence of the gas phase CA of nanobubbles.

The VOrtex Ring Transit EXperiment (VORTEX) GAS project

NASA Technical Reports Server (NTRS)

Bilen, Sven G.; Langenderfer, Lynn S.; Jardon, Rebecca D.; Cutlip, Hansford H.; Kazerooni, Alexander C.; Thweatt, Amber L.; Lester, Joseph L.; Bernal, Luis P.

1995-01-01

Get Away Special (GAS) payload G-093, also called VORTEX (VOrtex Ring Transit EXperiment), is an investigation of the propagation of a vortex ring through a liquid-gas interface in microgravity. This process results in the formation of one or more liquid droplets similar to earth based liquid atomization systems. In the absence of gravity, surface tension effects dominate the drop formation process. The Shuttle's microgravity environment allows the study of the same fluid atomization processes as using a larger drop size than is possible on Earth. This enables detailed experimental studies of the complex flow processes encountered in liquid atomization systems. With VORTEX, deformations in both the vortex ring and the fluid surface will be measured closely for the first time in a parameters range that accurately resembles liquid atomization. The experimental apparatus will record images of the interactions for analysis after the payload has been returned to earth. The current design of the VORTEX payload consists of a fluid test cell with a vortex ring generator, digital imaging system, laser illumination system, computer based controller, batteries for payload power, and an array of housekeeping and payload monitoring sensors. It is a self-contained experiment and will be flown on board the Space Shuttle in a 5 cubic feet GAS canister. The VORTEX Project is entirely run by students at the University of Michigan but is overseen by a faculty advisor acting as the payload customer and the contact person with NASA. This paper summarizes both the technical and programmatic aspects of the VORTEX Project.

Molecular Dynamics Study of the Bulk and Interface Properties of Frother and Oil with Saltwater and Air

DOE PAGES

Chong, Leebyn; Lai, Yungchieh; Gray, McMahan; ...

2017-03-15

For water treatment purposes, the separation processes involving surfactants and crude oil at seawater-air interfaces are of importance for chemical and energy industries. Little progress has been made in understanding the nanoscale phenomena of surfactants on oily saltwater-air interfaces. This work focuses on using molecular dynamics with a united-atom force field to simulate the interface of linear alkane oil, saltwater, and air with three surfactant frothers: methyl isobutyl carbinol (MIBC), terpineol, and ethyl glycol butyl ether (EGBE). For each frother, although the calculated diffusivities and viscosities are lower than the expected experimental values, our results showed that diffusivity trends betweenmore » each frother agree with experiments but was not suitable for viscosity. Binary combinations of liquid (frother or saltwater)-air and liquid-liquid interfaces are equilibrated to study the density profiles and interfacial tensions. The calculated surface tensions of the frothers-air interfaces are like that of oil-air, but lower than that of saltwater-air. Only MIBC-air and terpineol-air interfaces agreed with our experimental measurements. For frother-saltwater interfaces, the calculated results showed that terpineol has interfacial tensions higher than those of the MIBC-saltwater. Here, the simulated results indicated that the frother-oil systems underwent mixing such that the density profiles depicted large interfacial thicknesses.« less

Molecular Dynamics Study of the Bulk and Interface Properties of Frother and Oil with Saltwater and Air

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chong, Leebyn; Lai, Yungchieh; Gray, McMahan

For water treatment purposes, the separation processes involving surfactants and crude oil at seawater-air interfaces are of importance for chemical and energy industries. Little progress has been made in understanding the nanoscale phenomena of surfactants on oily saltwater-air interfaces. This work focuses on using molecular dynamics with a united-atom force field to simulate the interface of linear alkane oil, saltwater, and air with three surfactant frothers: methyl isobutyl carbinol (MIBC), terpineol, and ethyl glycol butyl ether (EGBE). For each frother, although the calculated diffusivities and viscosities are lower than the expected experimental values, our results showed that diffusivity trends betweenmore » each frother agree with experiments but was not suitable for viscosity. Binary combinations of liquid (frother or saltwater)-air and liquid-liquid interfaces are equilibrated to study the density profiles and interfacial tensions. The calculated surface tensions of the frothers-air interfaces are like that of oil-air, but lower than that of saltwater-air. Only MIBC-air and terpineol-air interfaces agreed with our experimental measurements. For frother-saltwater interfaces, the calculated results showed that terpineol has interfacial tensions higher than those of the MIBC-saltwater. Here, the simulated results indicated that the frother-oil systems underwent mixing such that the density profiles depicted large interfacial thicknesses.« less

Propagation of Sound in Matter.

DTIC Science & Technology

1982-03-01

Attenuation in Liquid Helium at 1 GHz; Technical Report No. 28, April 1969. 2. Kriss, Michael A., Size Effects in Liquid Helium II as Measured by Fourth...Helium, Technical Report No. 30, October 1969. 4. Scott, Stephen A., A Specific Heat and Fourth Sound Measurement of Size Effects in Liquid Helium...Rudnick, Superfluid Helmholtz Resonators, Phys. Rev. 174, No. 1, 326 (October 1968). 2. E. Guyon and I. Rudnick, Size Effects in Superfluid Helium II, Le

Interface for liquid chromatograph-mass spectrometer

DOEpatents

Andresen, B.D.; Fought, E.R.

1989-09-19

A moving belt interface is described for real-time, high-performance liquid chromatograph (HPLC)/mass spectrometer (MS) analysis which strips away the HPLC solvent as it emerges from the end of the HPLC column and leaves a residue suitable for mass-spectral analysis. The interface includes a portable, stand-alone apparatus having a plural stage vacuum station, a continuous ribbon or belt, a drive train magnetically coupled to an external drive motor, a calibrated HPLC delivery system, a heated probe tip and means located adjacent the probe tip for direct ionization of the residue on the belt. The interface is also capable of being readily adapted to fit any mass spectrometer. 8 figs.

Interface for liquid chromatograph-mass spectrometer

DOEpatents

Andresen, Brian D.; Fought, Eric R.

1989-01-01

A moving belt interface for real-time, high-performance liquid chromatograph (HPLC)/mass spectrometer (MS) analysis which strips away the HPLC solvent as it emerges from the end of the HPLC column and leaves a residue suitable for mass-spectral analysis. The interface includes a portable, stand-alone apparatus having a plural stage vacuum station, a continuous ribbon or belt, a drive train magnetically coupled to an external drive motor, a calibrated HPLC delivery system, a heated probe tip and means located adjacent the probe tip for direct ionization of the residue on the belt. The interface is also capable of being readily adapted to fit any mass spectrometer.

From Two-Phase to Three-Phase: The New Electrochemical Interface by Oxide Electrocatalysts

NASA Astrophysics Data System (ADS)

Xu, Zhichuan J.

2018-03-01

Electrochemical reactions typically occur at the interface between a solid electrode and a liquid electrolyte. The charge exchange behaviour between these two phases determines the kinetics of electrochemical reactions. In the past few years, significant advances have been made in the development of metal oxide electrocatalysts for fuel cell and electrolyser reactions. However, considerable gaps remain in the fundamental understanding of the charge transfer pathways and the interaction between the metal oxides and the conducting substrate on which they are located. In particular, the electrochemical interfaces of metal oxides are significantly different from the traditional (metal) ones, where only a conductive solid electrode and a liquid electrolyte are considered. Oxides are insulating and have to be combined with carbon as a conductive mediator. This electrode configuration results in a three-phase electrochemical interface, consisting of the insulating oxide, the conductive carbon, and the liquid electrolyte. To date, the mechanistic insights into this kind of non-traditional electrochemical interface remain unclear. Consequently conventional electrochemistry concepts, established on classical electrode materials and their two-phase interfaces, are facing challenges when employed for explaining these new electrode materials. [Figure not available: see fulltext.

Mathematical modeling of two phase stratified flow in a microchannel with curved interface

NASA Astrophysics Data System (ADS)

Dandekar, Rajat; Picardo, Jason R.; Pushpavanam, S.

2017-11-01

Stratified or layered two-phase flows are encountered in several applications of microchannels, such as solvent extraction. Assuming steady, unidirectional creeping flow, it is possible to solve the Stokes equations by the method of eigenfunctions, provided the interface is flat and meets the wall with a 90 degree contact angle. However, in reality the contact angle depends on the pair of liquids and the material of the channel, and differs significantly from 90 degrees in many practical cases. For unidirectional flow, this implies that the interface is a circular arc (of constant curvature). We solve this problem within the framework of eigenfunctions, using the procedure developed by Shankar. We consider two distinct cases: (a) the interface meets the wall with the equilibrium contact angle; (b) the interface is pinned by surface treatment of the walls, so that the flow rates determine the apparent contact angle. We show that the contact angle appreciably affects the velocity profile and the volume fractions of the liquids, while limiting the range of flow rates that can be sustained without the interface touching the top/bottom walls. Non-intuitively, we find that the pressure drop is reduced when the more viscous liquid wets the wall.

Dynamics of immiscible liquids in a rotating horizontal cylinder

NASA Astrophysics Data System (ADS)

Kozlov, N. V.; Kozlova, A. N.; Shuvalova, D. A.

2016-11-01

The dynamics of an interface between two immiscible liquids of different density is studied experimentally in a horizontal cylinder at rotation in the gravity field. Two liquids entirely fill the cavity volume, and the container is rotated sufficiently fast so that the liquids are centrifuged. The light liquid forms a column extended along the rotation axis, and the heavy liquid forms an annular layer. Under the action of gravity, the light liquid column displaces steadily along the radius, downwards in the laboratory frame. As a result, fluid oscillations in the cavity frame are excited at the interface, which lead to the generation of a steady streaming, and the fluid comes into a slow lagging rotation with respect to the cylinder walls. The dynamics of the studied system is determined by the ratio of the gravity acceleration to the centrifugal one—the dimensionless acceleration. In experiments, the system is controlled by the means of variation of the rotation rate, i.e., of the centrifugal force. At a critical value of the dimensionless acceleration the circular interface looses stability, and an azimuthal wave is excited. This leads to a strong increase in the interface differential velocity. A theoretical analysis is done based on the theory of centrifugal waves and a frequency equation is obtained. Experimental results are in good agreement with the theory at the condition of small wave amplitudes. Mechanism of steady streaming generation is analyzed based on previously published theoretical results obtained for the limiting case when the light phase is a solid cylinder. A qualitative agreement is found.

33 CFR 157.12d - Technical specifications.

Code of Federal Regulations, 2013 CFR

2013-07-01

... pipe runs full of liquid at all times during the discharge of the effluent. Sampling probes must... line as appropriate, so as to be always filled with the liquid being discharged. (2) A flow meter must... Design, Equipment, and Installation § 157.12d Technical specifications. (a) Oil discharge monitoring and...

33 CFR 157.12d - Technical specifications.

Code of Federal Regulations, 2012 CFR

2012-07-01

... pipe runs full of liquid at all times during the discharge of the effluent. Sampling probes must... line as appropriate, so as to be always filled with the liquid being discharged. (2) A flow meter must... Design, Equipment, and Installation § 157.12d Technical specifications. (a) Oil discharge monitoring and...

Growth of airway epithelial cells at an air-liquid interface changes both the response to particle exposure and iron homeostasis.

EPA Science Inventory

RATIONALE: We tested the hypothesis that 1) relative to submerged cells, airway epithelial cells grown at an air-liquid interface and allowed to differentiate would have an altered response to particle exposure and 2) that these differences would be associated with indices of iro...

Growth of airway epithelial cells at an air-liquid interface changes both the response to particle exposure and iron homeostasis

EPA Science Inventory

We tested the hypothesis that 1) relative to submerged cells, airway epithelial cells grown at an air-liquid interface and allowed to differentiate would have an altered response to particle exposure and 2) that these differences would be associated with indices of iron homeostas...

Disruption of an Aligned Dendritic Network by Bubbles During Re-Melting in a Microgravity Environment

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Brush, Lucien N.; Anilkumar, Amrutur V.

2012-01-01

The quiescent Microgravity environment can be quite dynamic. Thermocapillary flow about "large" static bubbles on the order of 1mm in diameter was easily observed by following smaller tracer bubbles. The bubble induced flow was seen to disrupt a large dendritic array, effectively distributing free branches about the solid-liquid interface. "Small" dynamic bubbles were observed to travel at fast velocities through the mushy zone with the implication of bringing/detaching/redistributing dendrite arm fragments at the solid-liquid interface. Large and small bubbles effectively re-orient/re-distribute dendrite branches/arms/fragments at the solid liquid interface. Subsequent initiation of controlled directional solidification results in growth of dendrites having random orientations which significantly compromises the desired science.

Adsorption parameters and phase behaviour of non-ionic surfactants at liquid interfaces.

PubMed

Slavchov, Radomir Iliev; Ivanov, Ivan Boyanov

2017-11-29

A reasonable adsorption model is one that allows all adsorption parameters (adsorption constant, hard-disc area α, attraction parameter β) of a surfactant at a liquid interface to be predicted accurately as a function of the molecular structure and medium conditions. However, the established adsorption models of van der Waals and Frumkin lead to inconsistencies, such as negative β at water|oil, α significantly larger than the crystallographic area of the molecule, and phase behaviour that contradicts the experimental observations. Several less popular models that are better suited for liquid interfaces are investigated. It is shown that the sticky disc model agrees with the observed adsorption behaviour of several homologous series of surfactants, both at water|air and water|oil interfaces. The area α is independent of the interface and agrees within 6% to what follows from collapse and crystallographic data. A model of the lateral attraction is proposed, from which it follows that β has a strongly non-linear dependence on the hydrocarbon chain length, the area of the head group and the temperature. Using the model of β, experimental data, and the law of corresponding states, the critical point of the adsorbed layer could be determined. Depending on the value of β, the adsorption behaviour of the surfactants at liquid interfaces can be classified into distinct categories: cohesive or non-cohesive, based on their Boyle points (where β = 2), and sub-critical or super-critical, based on their critical points (where β = 38.1).

Steady distribution structure of point defects near crystal-melt interface under pulling stop of CZ Si crystal

NASA Astrophysics Data System (ADS)

Abe, T.; Takahashi, T.; Shirai, K.

2017-02-01

In order to reveal a steady distribution structure of point defects of no growing Si on the solid-liquid interface, the crystals were grown at a high pulling rate, which Vs becomes predominant, and the pulling was suddenly stopped. After restoring the variations of the crystal by the pulling-stop, the crystals were then left in prolonged contact with the melt. Finally, the crystals were detached and rapidly cooled to freeze point defects and then a distribution of the point defects of the as-grown crystals was observed. As a result, a dislocation loop (DL) region, which is formed by the aggregation of interstitials (Is), was formed over the solid-liquid interface and was surrounded with a Vs-and-Is-free recombination region (Rc-region), although the entire crystals had been Vs rich in the beginning. It was also revealed that the crystal on the solid-liquid interface after the prolonged contact with the melt can partially have a Rc-region to be directly in contact with the melt, unlike a defect distribution of a solid-liquid interface that has been growing. This experimental result contradicts a hypothesis of Voronkov's diffusion model, which always assumes the equilibrium concentrations of Vs and Is as the boundary condition for distribution of point defects on the growth interface. The results were disscussed from a qualitative point of view of temperature distribution and thermal stress by the pulling-stop.

Railroad track inspection interface demonstration : final report.

DOT National Transportation Integrated Search

2016-01-01

This project developed a track data user interface utilizing the Google Glass optical display device. The interface allows the user : to recall data stored remotely and view the data on the Google Glass. The technical effort required developing a com...

Introduction to optical methods for characterizing liquid crystals at interfaces.

PubMed

Miller, Daniel S; Carlton, Rebecca J; Mushenheim, Peter C; Abbott, Nicholas L

2013-03-12

This Instructional Review describes methods and underlying principles that can be used to characterize both the orientations assumed spontaneously by liquid crystals (LCs) at interfaces and the strength with which the LCs are held in those orientations (so-called anchoring energies). The application of these methods to several different classes of LC interfaces is described, including solid and aqueous interfaces as well as planar and nonplanar interfaces (such as those that define a LC-in-water emulsion droplet). These methods, which enable fundamental studies of the ordering of LCs at polymeric, chemically functionalized, and biomolecular interfaces, are described in this Instructional Review on a level that can be easily understood by a nonexpert reader such as an undergraduate or graduate student. We focus on optical methods because they are based on instrumentation that is found widely in research and teaching laboratories.

Active oil-water interfaces: buckling and deformation of oil drops by bacteria

NASA Astrophysics Data System (ADS)

Juarez, Gabriel; Stocker, Roman

2014-11-01

Bacteria are unicellular organisms that seek nutrients and energy for growth, division, and self-propulsion. Bacteria are also natural colloidal particles that attach and self-assemble at liquid-liquid interfaces. Here, we present experimental results on active oil-water interfaces that spontaneously form when bacteria accumulate or grow on the interface. Using phase-contrast and fluorescence microscopy, we simultaneously observed the dynamics of adsorbed Alcanivorax bacteria and the oil-water interface within microfluidic devices. We find that, by growing and dividing, adsorbed bacteria form a jammed monolayer of cells that encapsulates the entire oil drop. As bacteria continue to grow at the interface, the drop buckles and the interface undergoes strong deformations. The bacteria act to stabilize non-equilibrium shapes of the oil-phase such wrinkling and tubulation. In addition to presenting a natural example of a living interface, these findings shape our understanding of microbial degradation of oil and may have important repercussions on engineering interventions for oil bioremediation.

A parallel interaction potential approach coupled with the immersed boundary method for fully resolved simulations of deformable interfaces and membranes

NASA Astrophysics Data System (ADS)

Spandan, Vamsi; Meschini, Valentina; Ostilla-Mónico, Rodolfo; Lohse, Detlef; Querzoli, Giorgio; de Tullio, Marco D.; Verzicco, Roberto

2017-11-01

In this paper we show and discuss how the deformation dynamics of closed liquid-liquid interfaces (for example drops and bubbles) can be replicated with use of a phenomenological interaction potential model. This new approach to simulate liquid-liquid interfaces is based on the fundamental principle of minimum potential energy where the total potential energy depends on the extent of deformation of a spring network distributed on the surface of the immersed drop or bubble. Simulating liquid-liquid interfaces using this model require computing ad-hoc elastic constants which is done through a reverse-engineered approach. The results from our simulations agree very well with previous studies on the deformation of drops in standard flow configurations such as a deforming drop in a shear flow or cross flow. The interaction potential model is highly versatile, computationally efficient and can be easily incorporated into generic single phase fluid solvers to also simulate complex fluid-structure interaction problems. This is shown by simulating flow in the left ventricle of the heart with mechanical and natural mitral valves where the imposed flow, motion of ventricle and valves dynamically govern the behaviour of each other. Results from these simulations are compared with ad-hoc in-house experimental measurements. Finally, we present a simple and easy to implement parallelisation scheme, as high performance computing is unavoidable when studying large scale problems involving several thousands of simultaneously deforming bodies in highly turbulent flows.

Possible fossil H2O liquid-ice interfaces in the Martian crust

NASA Technical Reports Server (NTRS)

Soderblom, L. A.; Wenner, D. B.

1978-01-01

The extensive chaotic and fretted terrains in the equatorial regions of Mars are explained on the basis of the vertical distribution of H2O liquid and ice which once existed in the crust. This account assumes that below the permafrost containing water ice, there was a second zone in which liquid water resided for at least a time. Diagenetic alteration and cementation characterized the material in the subpermafrost zone; above, pristine fragmented material with various ice concentrations was found. Later, the ice-laden zone was stripped away by a number of erosional processes, exposing the former ice-liquid water interface.

Water evaporation: a transition path sampling study.

PubMed

Varilly, Patrick; Chandler, David

2013-02-07

We use transition path sampling to study evaporation in the SPC/E model of liquid water. On the basis of thousands of evaporation trajectories, we characterize the members of the transition state ensemble (TSE), which exhibit a liquid-vapor interface with predominantly negative mean curvature at the site of evaporation. We also find that after evaporation is complete, the distributions of translational and angular momenta of the evaporated water are Maxwellian with a temperature equal to that of the liquid. To characterize the evaporation trajectories in their entirety, we find that it suffices to project them onto just two coordinates: the distance of the evaporating molecule to the instantaneous liquid-vapor interface and the velocity of the water along the average interface normal. In this projected space, we find that the TSE is well-captured by a simple model of ballistic escape from a deep potential well, with no additional barrier to evaporation beyond the cohesive strength of the liquid. Equivalently, they are consistent with a near-unity probability for a water molecule impinging upon a liquid droplet to condense. These results agree with previous simulations and with some, but not all, recent experiments.

Sharp Interface Tracking in Rotating Microflows of Solvent Extraction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Glimm, James; Almeida, Valmor de; Jiao, Xiangmin

2013-01-08

The objective of this project is to develop a specialized sharp interface tracking simulation capability for predicting interaction of micron-sized drops and bubbles in rotating flows relevant to optimized design of contactor devices used in solvent extraction processes of spent nuclear fuel reprocessing. The primary outcomes of this project include the capability to resolve drops and bubbles micro-hydrodynamics in solvent extraction contactors, determining from first principles continuum fluid mechanics how micro-drops and bubbles interact with each other and the surrounding shearing fluid for realistic flows. In the near term, this effort will play a central role in providing parameters andmore » insight into the flow dynamics of models that average over coarser scales, say at the millimeter unit length. In the longer term, it will prove to be the platform to conduct full-device, detailed simulations as parallel computing power reaches the exaflop level. The team will develop an accurate simulation tool for flows containing interacting droplets and bubbles with sharp interfaces under conditions that mimic those found in realistic contactor operations. The main objective is to create an off-line simulation capability to model drop and bubble interactions in a domain representative of the averaged length scale. The technical approach is to combine robust interface tracking software, subgrid modeling, validation quality experiments, powerful computational hardware, and a team with simulation modeling, physical modeling and technology integration experience. Simulations will then fully resolve the microflow of drops and bubbles at the microsecond time scale. This approach is computationally intensive but very accurate in treating important coupled physical phenomena in the vicinity of interfaces. The method makes it possible to resolve spatial scales smaller than the typical distance between bubbles and to model some non-equilibrium thermodynamic features such as finite critical tension in cavitating liquids« less

Mean-field kinetic theory approach to evaporation of a binary liquid into vacuum

NASA Astrophysics Data System (ADS)

Frezzotti, A.; Gibelli, L.; Lockerby, D. A.; Sprittles, J. E.

2018-05-01

Evaporation of a binary liquid into near-vacuum conditions has been studied using numerical solutions of a system of two coupled Enskog-Vlasov equations. Liquid-vapor coexistence curves have been mapped out for different liquid compositions. The evaporation process has been investigated at a range of liquid temperatures sufficiently lower than the critical one for the vapor not to significantly deviate from the ideal behavior. It is found that the shape of the distribution functions of evaporating atoms is well approximated by an anisotropic Maxwellian distribution with different characteristic temperatures for velocity components normal and parallel to the liquid-vapor interface. The anisotropy reduces as the evaporation temperature decreases. Evaporation coefficients are computed based on the separation temperature and the maximum concentration of the less volatile component close to the liquid-vapor interface. This choice leads to values which are almost constant in the simulation conditions.

Cognitive Task Analysis, Interface Design, and Technical Troubleshooting.

ERIC Educational Resources Information Center

Steinberg, Linda S.; Gitomer, Drew H.

A model of the interface design process is proposed that makes use of two interdependent levels of cognitive analysis: the study of the criterion task through an analysis of expert/novice differences and the evaluation of the working user interface design through the application of a practical interface analysis methodology (GOMS model). This dual…

TangibleCubes — Implementation of Tangible User Interfaces through the Usage of Microcontroller and Sensor Technology

NASA Astrophysics Data System (ADS)

Setscheny, Stephan

The interaction between human beings and technology builds a central aspect in human life. The most common form of this human-technology interface is the graphical user interface which is controlled through the mouse and the keyboard. In consequence of continuous miniaturization and the increasing performance of microcontrollers and sensors for the detection of human interactions, developers receive new possibilities for realising innovative interfaces. As far as this movement is concerned, the relevance of computers in the common sense and graphical user interfaces is decreasing. Especially in the area of ubiquitous computing and the interaction through tangible user interfaces a highly impact of this technical evolution can be seen. Apart from this, tangible and experience able interaction offers users the possibility of an interactive and intuitive method for controlling technical objects. The implementation of microcontrollers for control functions and sensors enables the realisation of these experience able interfaces. Besides the theories about tangible user interfaces, the consideration about sensors and the Arduino platform builds a main aspect of this work.

Comparison of the Booster Interface Temperature in Stainless Steel (SS) V-Channel versus the Aluminum (Al) Y-Channel Primer Chamber Assemblies (PCAs). Volume 1; Technical Assessment Report

NASA Technical Reports Server (NTRS)

Garcia, Roberto; Saulsberry, Regor L.

2011-01-01

NASA's Technical Fellow for Propulsion, requested a technical assessment of the performance improvement achieved by the introduction of the stainless steel (SS) V-channel compared to the aluminum (Al) Y-channel Primer Chamber Assembly (PCA) design. The SS V-channel PCA was developed for NASA's Mars Science Laboratory (MSL) Project. The principle focus of the assessment was to measure the transient temperature at the booster interface with both designs. This document contains the findings of the assessment.

Liquid/liquid interface layering of 1-butanol and [bmim]PF6 ionic liquid: a nonlinear vibrational spectroscopy and molecular dynamics simulation study.

PubMed

Iwahashi, Takashi; Ishiyama, Tatsuya; Sakai, Yasunari; Morita, Akihiro; Kim, Doseok; Ouchi, Yukio

2015-10-14

IR-visible sum-frequency generation (IV-SFG) vibrational spectroscopy and a molecular dynamics (MD) simulation were used to study the local layering order at the interface of 1-butanol-d9 and 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF6), a room-temperature ionic liquid (RTIL). The presence of a local non-polar layer at the interface of the two polar liquids was successfully demonstrated. In the SFG spectra of 1-butanol-d9, we observed significant reduction and enhancement in the strength of the CD3 symmetric stretching (r(+)) mode and the antisymmetric stretching (r(-)) mode peaks, respectively. The results can be well explained by the presence of an oppositely oriented quasi-bilayer structure of butanol molecules, where the bottom layer is strongly bound by hydrogen-bonding with the PF6(-) anion. MD simulations reveal that the hydrogen-bonding of butanol with the PF6(-) anion causes the preferential orientation of the butanols; the restriction on the rotational distribution of the terminal methyl group along their C3 axis enhances the r(-) mode. As for the [bmim](+) cations, the SFG spectra taken within the CH stretch region indicate that the butyl chain of [bmim](+) points away from the bulk RTIL phase to the butanol phase at the interface. Combining the SFG spectroscopy and MD simulation results, we propose an interfacial model structure of layering, in which the butyl chains of the butanol molecules form a non-polar interfacial layer with the butyl chains of the [bmim](+) cations at the interface.

Effects of surface tension and intraluminal fluid on mechanics of small airways.

PubMed

Hill, M J; Wilson, T A; Lambert, R K

1997-01-01

Airway constriction is accompanied by folding of the mucosa to form ridges that run axially along the inner surface of the airways. The mucosa has been modeled (R. K. Lambert. J. Appl. Physiol. 71:666-673, 1991) as a thin elastic layer with a finite bending stiffness, and the contribution of its bending stiffness to airway elastance has been computed. In this study, we extend that work by including surface tension and intraluminal fluid in the model. With surface tension, the pressure on the inner surface of the elastic mucosa is modified by the pressure difference across the air-liquid interface. As folds form in the mucosa, intraluminal fluid collects in pools in the depressions formed by the folds, and the curvature of the air-liquid interface becomes nonuniform. If the amount of intraluminal fluid is small, < 2% of luminal volume, the pools of intraluminal fluid are small, the air-liquid interface nearly coincides with the surface of the mucosa, and the area of the air-liquid interface remains constant as airway cross-sectional area decreases. In that case, surface energy is independent of airway area, and surface tension has no effect on airway mechanics. If the amount of intraluminal fluid is > 2%, the area of the air-liquid interface decreases as airway cross-sectional area decreases. and surface tension contributes to airway compression. The model predicts that surface tension plus intraluminal fluid can cause an instability in the area-pressure curve of small airways. This instability provides a mechanism for abrupt airway closure and abrupt reopening at a higher opening pressure.

Quantitative Interpretation of Polarization SFG Vibrational Spectra of Air/Methanol Interface

NASA Astrophysics Data System (ADS)

Wu, Hui; Zhang, Wen-kai; Gan, Wei; Cui, Zhi-feng; Wang, Hong-fei

2006-06-01

Even though in IR and Raman spectra of liquid methanol there is always an apparent feature for the asymmetric stretching mode of the CH3 group around 2970 cm-1, this feature has not been observed in the Sum Frequency Generation Vibrational Spectroscopy (SFG-VS) in any polarizations from the air/methanol interface. Here we present a treatment based on a corrected bond additivity model to quantitatively interpret the SFG-VS of the air/methanol interface from the IR and Raman spectra of liquid methanol.

Comprehensive two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography for analysis of toad skin.

PubMed

Li, Jia-Fu; Yan, Xia; Wu, Yun-Long; Fang, Mei-Juan; Wu, Zhen; Qiu, Ying-Kun

2017-04-15

An analytical two-dimensional normal-phase liquid chromatography × reversed-phase liquid chromatography (2D NPLC × RPLC) system was constructed with a newly developed thermal evaporation assisted adsorption (TEAA) interface. This novel TEAA interface with heating temperature above solvent boiling point allowed fast removal of organic NPLC solvent and successfully solved the solvent incompatibility problem between NPLC and RPLC. The system achieved rapid on-line solvent exchange between the two dimensions within a short modulation time of 190 s and was applied in the analysis of an extract from the skin of Bufo bufo gargarizans. This is the first time to realize the on-line comprehensive analysis of a moderate polar natural product by coupling NPLC with reversed phase ultra-high performance liquid chromatography (UHPLC). To be highlighted, with the TEAA interface, the 2D NPLC × RPLC system provided excellent resolution and orthogonality (75.2%), when compared with that of 2D RPLC × RPLC. Copyright © 2017 Elsevier B.V. All rights reserved.

Spontaneous Self-Formation of 3D Plasmonic Optical Structures.

PubMed

Choi, Inhee; Shin, Yonghee; Song, Jihwan; Hong, SoonGweon; Park, Younggeun; Kim, Dongchoul; Kang, Taewook; Lee, Luke P

2016-08-23

Self-formation of colloidal oil droplets in water or water droplets in oil not only has been regarded as fascinating fundamental science but also has been utilized in an enormous number of applications in everyday life. However, the creation of three-dimensional (3D) architectures by a liquid droplet and an immiscible liquid interface has been less investigated than other applications. Here, we report interfacial energy-driven spontaneous self-formation of a 3D plasmonic optical structure at room temperature without an external force. Based on the densities and interfacial energies of two liquids, we simulated the spontaneous formation of a plasmonic optical structure when a water droplet containing metal ions meets an immiscible liquid polydimethylsiloxane (PDMS) interface. At the interface, the metal ions in the droplet are automatically reduced to form an interfacial plasmonic layer as the liquid PDMS cures. The self-formation of both an optical cavity and integrated plasmonic nanostructure significantly enhances the fluorescence by a magnitude of 1000. Our findings will have a huge impact on the development of various photonic and plasmonic materials as well as metamaterials and devices.

Massive radius-dependent flow slippage in carbon nanotubes

PubMed Central

Secchi, Eleonora; Marbach, Sophie; Niguès, Antoine; Stein, Derek; Siria, Alessandro; Bocquet, Lydéric

2016-01-01

Simulations and measurements have established that water moves through carbon nanotubes with exceptionally high rates due to nearly frictionless interfaces1–4. These observations have stimulated interest in nanotube-based membranes for applications that range from desalination to nano-filtration and energy harvesting5–10, yet the exact water transport mechanisms inside the nanotubes and at the water-carbon interface continue to be controversially discussed11,12 because existing theories fail to provide a satisfying explanation for the limited number of experimental results available to date13. This is because even though controlled and systematic studies have explored transport through individual nanotubes8,9,14–7, none has met the considerable technical challenge of unambiguously measuring the permeability of a single nanotube11. Here we show that the pressure-driven flow rate across individual nanotubes can be determined with unprecedented sensitivity and without dyes from the hydrodynamics of water jets as they emerge from single nanotubes into a surrounding fluid. Our measurements reveal unexpectedly large and radius-dependent surface slippage in carbon nanotubes (CNT), and no slippage in boron-nitride nanotubes (BNNT) that are crystallographically similar to CNTs but differ electronically. This pronounced contrast between the two systems must originate from subtle differences in atomic-scale details of their solid-liquid interfaces, strikingly illustrating that nanofluidics is the frontier where the continuum picture of fluid mechanics confronts the atomic nature of matter. PMID:27604947

Adsorption of 1- and 2-butylimidazoles at the copper/air and steel/air interfaces studied by sum frequency generation vibrational spectroscopy.

PubMed

Casford, Michael T L; Davies, Paul B

2012-07-24

The structure of thin films of 1- and 2-butylimidazoles adsorbed on copper and steel surfaces under air was examined using sum frequency generation (SFG) vibrational spectroscopy in the ppp and ssp polarizations. Additionally, the SFG spectra of both isomers were recorded at 55 °C at the liquid imidazole/air interface for reference. Complementary bulk infrared, reflection-absorption infrared spectroscopy (RAIRS), and Raman spectra of both imidazoles were recorded for assignment purposes. The SFG spectra in the C-H stretching region at the liquid/air interface are dominated by resonances from the methyl end group of the butyl side chain of the imidazoles, indicating that they are aligned parallel or closely parallel to the surface normal. These are also the most prominent features in the SFG spectra on copper and steel. In addition, both the ppp and ssp spectra on copper show resonances from the C-H stretching modes of the imidazole ring for both isomers. The ring C-H resonances are completely absent from the spectra on steel and at the liquid/air interface. The relative intensities of the SFG spectra can be interpreted as showing that, on copper, under air, both butylimidazoles are adsorbed with their butyl side chains perpendicular to the interface and with the ring significantly inclined away from the surface plane and toward the surface normal. The SFG spectra of both imidazoles on steel indicate an orientation where the imidazole rings are parallel or nearly parallel to the surface. The weak C-H resonances from the ring at the liquid/air interface suggest that the tilt angle of the ring from the surface normal at this interface is significantly greater than it is on copper.

UV-Vis reflection spectroscopy under variable angle incidence at the air-liquid interface.

PubMed

Roldán-Carmona, Cristina; Rubia-Payá, Carlos; Pérez-Morales, Marta; Martín-Romero, María T; Giner-Casares, Juan J; Camacho, Luis

2014-03-07

The UV-Vis reflection spectroscopy (UV-Vis-RS) in situ at the air-liquid interface provides information about tilt and aggregation of chromophores in Langmuir monolayers. This information is particularly important given in most cases the chromophore is located at the polar region of the Langmuir monolayer. This region of the Langmuir monolayers has been hardly accessible by other experimental techniques. In spite of its enormous potential, the application of UV-Vis-RS has been limited mainly to reflection measurements under light normal incidence or at lower incidence angles than the Brewster angle. Remarkably, this technique is quite sensitive to the tilt of the chromophores at values of incidence angles close to or larger than the Brewster angle. Therefore, a novel method to obtain the order parameter of the chromophores at the air-liquid interface by using s- and p-polarized radiation at different incidence angles is proposed. This method allowed for the first time the experimental observation of the two components with different polarization properties of a single UV-Vis band at the air-liquid interface. The method of UV-Vis spectroscopy under variable angle incidence is presented as a new tool for obtaining rich detailed information on Langmuir monolayers.

Thermocapillary convection in two immiscible liquid layers with free surface

NASA Technical Reports Server (NTRS)

Doi, Takao; Koster, Jean N.

1993-01-01

Thermocapillary convection is studied in two immiscible liquid layers with one free surface, one liquid/liquid interface, and differential heating applied parallel to the interfaces. An analytical solution is introduced for infinite horizontal layers. The defining parameter for the flow pattern is lambda, the ratio of the temperature coefficient of the interfacial tension to that of the surface tension. Four different flow patterns exist under zero gravity conditions. 'Halt' conditions which halt the fluid motion in the lower encapsulated liquid layer have been found. A numerical experiment is carried out to study effects of vertical end walls on the double layer convection in a 2D cavity. The halt condition obtained from the analytical study is found to be valid in the limit of small Reynolds numbers. The flow in the encapsulated liquid layer can be suppressed substantially.

Fluorinated pickering emulsions impede interfacial transport and form rigid interface for the growth of anchorage-dependent cells.

PubMed

Pan, Ming; Rosenfeld, Liat; Kim, Minkyu; Xu, Manqi; Lin, Edith; Derda, Ratmir; Tang, Sindy K Y

2014-12-10

This study describes the design and synthesis of amphiphilic silica nanoparticles for the stabilization of aqueous drops in fluorinated oils for applications in droplet microfluidics. The success of droplet microfluidics has thus far relied on one type of surfactant for the stabilization of drops. However, surfactants are known to have two key limitations: (1) interdrop molecular transport leads to cross-contamination of droplet contents, and (2) the incompatibility with the growth of adherent mammalian cells as the liquid-liquid interface is too soft for cell adhesion. The use of nanoparticles as emulsifiers overcomes these two limitations. Particles are effective in mitigating undesirable interdrop molecular transport as they are irreversibly adsorbed to the liquid-liquid interface. They do not form micelles as surfactants do, and thus, a major pathway for interdrop transport is eliminated. In addition, particles at the droplet interface provide a rigid solid-like interface to which cells could adhere and spread, and are thus compatible with the proliferation of adherent mammalian cells such as fibroblasts and breast cancer cells. The particles described in this work can enable new applications for high-fidelity assays and for the culture of anchorage-dependent cells in droplet microfluidics, and they have the potential to become a competitive alternative to current surfactant systems for the stabilization of drops critical for the success of the technology.

Photoinduced Electron Transfer of PAMAM Dendrimer-Zinc(II) Porphyrin Associates at Polarized Liquid|Liquid Interfaces.

PubMed

Nagatani, Hirohisa; Sakae, Hiroki; Torikai, Taishi; Sagara, Takamasa; Imura, Hisanori

2015-06-09

The heterogeneous photoinduced electron-transfer reaction of the ion associates between NH2-terminated polyamidoamine (PAMAM) dendrimers and 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrinato zinc(II) (ZnTPPS(4-)) was studied at the polarized water|1,2-dichloroethane (DCE) interface. The positive photocurrent arising from the photoreduction of ZnTPPS(4-) by a lipophilic quencher, decamethylferrocene, in the interfacial region was significantly enhanced by the ion association with the PAMAM dendrimers. The photocurrent response of the dendrimer-ZnTPPS(4-) associates was dependent on the pH condition and on the generation of dendrimer. A few cationic additives such as polyallylamine and n-octyltrimethyammonium were also examined as alternatives to the PAMAM dendrimer, but the magnitude of the photocurrent enhancement was rather small. The high photoreactivity of the dendrimer-ZnTPPS(4-) associates was interpreted mainly as a result of the high interfacial concentration of photoreactive porphyrin units associated stably with the dendrimer which was preferably adsorbed at the polarized water|DCE interface. The photochemical data observed in the second and fourth generation PAMAM dendrimer systems demonstrated that the higher generation dendrimer which can incorporate a porphyrin molecule more completely in the interior is less efficient for the photocurrent enhancement at the interface. These results indicated that the photoreactivity of ionic reactant at a polarized liquid|liquid interface can readily be modified via ion association with the charged dendrimer.

Experimental and Numerical Study of the Evaporation of Water at Low Pressures.

PubMed

Kazemi, Mohammad Amin; Nobes, David S; Elliott, Janet A W

2017-05-09

Although evaporation is considered to be a surface phenomenon, the rate of molecular transport across a liquid-vapor boundary is strongly dependent on the coupled fluid dynamics and heat transfer in the bulk fluids. Recent experimental thermocouple measurements of the temperature field near the interface of evaporating water into its vapor have begun to show the role of heat transfer in evaporation. However, the role of fluid dynamics has not been explored sufficiently. Here, we have developed a mathematical model to describe the coupling of the heat, mass, and momentum transfer in the fluids with the transport phenomena at the interface. The model was used to understand the experimentally obtained velocity field in the liquid and temperature profiles in the liquid and vapor, in evaporation from a concave meniscus for various vacuum pressures. By using the model, we have shown that an opposing buoyancy flow suppressed the thermocapillary flow in the liquid during evaporation at low pressures in our experiments. As such, in the absence of thermocapillary convection, the evaporation is controlled by heat transfer to the interface, and the predicted behavior of the system is independent of choosing between the existing theoretical expressions for evaporation flux. Furthermore, we investigated the temperature discontinuity at the interface and confirmed that the discontinuity strongly depends on the heat flux from the vapor side, which depends on the geometrical shape of the interface.

Mathematic modeling of the method of measurement relative dielectric permeability

NASA Astrophysics Data System (ADS)

Plotnikova, I. V.; Chicherina, N. V.; Stepanov, A. B.

2018-05-01

The method of measuring relative permittivity’s and the position of the interface between layers of a liquid medium is considered in the article. An electric capacitor is a system consisting of two conductors that are separated by a dielectric layer. It is mathematically proven that at any given time it is possible to obtain the values of the relative permittivity in the layers of the liquid medium and to determine the level of the interface between the layers of the two-layer liquid. The estimation of measurement errors is made.

Measuring the surface tension of a liquid-gas interface by automatic stalagmometer

NASA Astrophysics Data System (ADS)

Molina, C.; Victoria, L.; Arenas, A.

2000-06-01

We present a variation of the stalagmometer method for automatically determining the surface tension of a liquid-gas interface using a pressure sensor to measure the pressure variation per drop. The presented method does not depend on a knowledge of the density of the problem liquid and obtains values with a measurement error in the range of 1%-2%. Its low cost and simplicity mean that the technique can be used in the teaching and instrumentation laboratory in the same way as other methods.

Liquid management in low gravity using baffled rotating containers

NASA Technical Reports Server (NTRS)

Gans, R. F.

1985-01-01

Possible static configurations of liquids in rotating cylindrical containers with baffles evenly spaced in the axial direction are found. The force balance is among surface tension, centrifugal force and gravity. Two instabilities are found in this parameter space: type 1 is the inability of the liquid to form an interface attached to the baffles; type 2 is the inability for multi-baffled configurations to sustain interfaces between each pair of baffles. The type 1 analysis is confirmed through laboratory based equipment. Applications to orbiting containers are discussed.

Liquid management in low gravity using baffled rotating containers

NASA Technical Reports Server (NTRS)

Gans, R. F.

1984-01-01

Possible static configurations of liquids in rotating cylindrical containers with baffles evenly spaced in the axial direction are found. The force balance is among surface tension, centrifugal force and gravity. Two instabilities are found in this parameter space: type 1 is the inability of the liquid to form an interface attached to the baffles; type 2 is the inability for multi-baffled configurations to sustain interfaces between each pair of baffles. The type 1 analysis is confirmed through laboratory based equipment. Applications to orbiting containers are discussed.

Biomechanical ordering and buckling due to microbial growth confined at oil-water interfaces

NASA Astrophysics Data System (ADS)

Juarez, Gabriel; Stocker, Roman

2015-11-01

Bacteria are unicellular organisms that often exist as densely populated, surface-associated communities. Bacteria are also environmental colloids and spontaneously attach and self-assemble at liquid-liquid interfaces. Here, we present results on the growth dynamics of individual rod-shaped bacteria confined to finite oil-water interfaces of varying curvature. Through experiments using microfluidic chambers and time-lapse microscopy, we study the formation of macroscopic structures observed as adsorbed bacteria grow, divide, and self-assemble in a nematic phase due to biomechanical interactions. The continued growth at the interface leads to a jammed monolayer of cells, which then causes the interface to buckle and undergo large deformations including wrinkling and tubulation. These observations highlight the interplay between physical environment, such as confinement and interface curvature, and active biological processes, such as growth, at the scale of individual agents and shape our understanding of macroscale processes such as microbial degradation of oil in the ocean.

Experimental determination and numerical modelling of solid liquid interface shapes for vertical Bridgman grown GaSb crystals

NASA Astrophysics Data System (ADS)

Boiton, P.; Giacometti, N.; Santailler, J. L.; Duffar, T.; Nabot, J. P.

1998-11-01

A facility, based on a profiled resistive heater, has been designed for the growth of antimonide crystals (GaSb, InSb) by the vertical Bridgman method. Solid-liquid interface shapes during the growth of 2-in diameter crystals are marked by means of variations of the pulling rate and are revealed by chemical etching. The comparison with the calculated interface shapes, obtained using a finite element method, gives a satisfactory agreement. It is shown that the heat transfer and consequently the interface shapes are greatly influenced by the crucible assembly. For example, small spacings around the crucible or slots in the crucible holder can change the interface curvature from convex to concave. From numerical simulations it is also shown that convection in the melt flattens the interface but that an increase of the pulling rate has the reverse effect.

Instructional Review: An Introduction to Optical Methods for Characterizing Liquid Crystals at Interfaces

PubMed Central

Miller, Daniel S.; Carlton, Rebecca J.; Mushenheim, Peter C.; Abbott, Nicholas L.

2013-01-01

This Instructional Review describes methods and underlying principles that can be used to characterize both the orientations assumed spontaneously by liquid crystals (LCs) at interfaces and the strength with which the LCs are held in those orientations (so-called anchoring energies). The application of these methods to several different classes of LC interfaces is described, including solid and aqueous interfaces as well as planar and non-planar interfaces (such as those that define a LC-in-water emulsion droplet). These methods, which enable fundamental studies of the ordering of LCs at polymeric, chemically-functionalized and biomolecular interfaces, are described in this article at a level that can be easily understood by a non-expert reader such as an undergraduate or graduate student. We focus on optical methods because they are based on instrumentation that is found widely in research and teaching laboratories. PMID:23347378

Probing alpha-helical and beta-sheet structures of peptides at solid/liquid interfaces with SFG.

PubMed

Chen, Xiaoyun; Wang, Jie; Sniadecki, Jason J; Even, Mark A; Chen, Zhan

2005-03-29

We demonstrated that sum frequency generation (SFG) vibrational spectroscopy can distinguish different secondary structures of proteins or peptides adsorbed at solid/liquid interfaces. The SFG spectrum for tachyplesin I at the polystyrene (PS)/solution interface has a fingerprint peak corresponding to the B1/B3 mode of the antiparallel beta-sheet. This peak disappeared upon the addition of dithiothreitol, which can disrupt the beta-sheet structure. The SFG spectrum indicative of the MSI594 alpha-helical structure was observed at the PS/MSI594 solution interface. This research validates SFG as a powerful technique for revealing detailed secondary structures of interfacial proteins and peptides.

Bubble Induced Disruption of a Planar Solid-Liquid Interface During Controlled Directional Solidification in a Microgravity Environment

NASA Technical Reports Server (NTRS)

Grugel, Richard N.; Brush, Lucien N.; Anilkumar, Amrutur V.

2013-01-01

Pore Formation and Mobility Investigation (PFMI) experiments were conducted in the microgravity environment aboard the International Space Station with the intent of better understanding the role entrained porosity/bubbles play during controlled directional solidification. The planar interface in a slowing growing succinonitrile - 0.24 wt% water alloy was being observed when a nitrogen bubble traversed the mushy zone and remained at the solid-liquid interface. Breakdown of the interface to shallow cells subsequently occurred, and was later evaluated using down-linked data from a nearby thermocouple. These results and other detrimental effects due to the presence of bubbles during solidification processing in a microgravity environment are presented and discussed.

Interface stability in a slowly rotating, low gravity tank Experiments

NASA Technical Reports Server (NTRS)

Leslie, F.; Gans, R. F.

1986-01-01

Analytical models of liquid in partially-filled rotating tanks predict both the shape of the interface between the liquid and its vapor, and the stability of that interface. The models are of necessity incomplete and experimental data are needed to assess the approximations made. Presented are preliminary experimental studies both in the laboratory and in the low-gravity environment of a free-falling aircraft. Emphasis is placed on bubbles which intersect the container boundaries. Measurements of rotating equilibrium bubble shapes are in agreement with theoretical profiles derived from Laplace's formula. The interface shape depends on the contact angle, the radius of intersection with container, and the ratio of centrifugal force to surface tension.

Influence of granulometry in the Hurst exponent of air liquid interfaces formed during capillary rising in a granular media

NASA Astrophysics Data System (ADS)

Gontijo, Guilherme L.; Souza, Flávia B.; Braga, Rafael M. L.; Silva, Pedro H. E.; Correia, Maury D.; Atman, A. P. F.

2017-06-01

We report results concerning the fractal dimension of a air/fluid interface formed during the capillary rising of a fluid into a dense granular media. The system consists in a modified Hele-Shaw cell filled with grains at different granulometries and confined in a narrow gap between the glass plates. The system is then placed onto a water reservoir, and the liquid penetrates the medium due to capillary forces. We measure the Hurst exponent of the liquid/air interface with help of image processing, and follow the temporal evolution of the profiles. We observe that the Hurst exponent can be related with the granulometry, but the range of values are odd to the predicted values from models or theory.

PREFACE: Liquid-solid interfaces: structure and dynamics from spectroscopy and simulations Liquid-solid interfaces: structure and dynamics from spectroscopy and simulations

NASA Astrophysics Data System (ADS)

Gaigeot, Marie-Pierre; Sulpizi, Marialore

2012-03-01

Liquid-solid interfaces play an important role in a number of phenomena encountered in biological, chemical and physical processes. Surface-induced changes of the material properties are not only important for the solid support but also for the liquid itself. In particular, it is now well established that water at the interface is substantially different from bulk water, even in the proximity of apparently inert surfaces such as a simple metal. The complex chemistry at liquid-solid interfaces is typically fundamental to heterogeneous catalysis and electrochemistry, and has become especially topical in connection with the search for new materials for energy production. A quite remarkable example is the development of cheap yet efficient solar cells, whose basic components are dye molecules grafted to the surface of an oxide material and in contact with an electrolytic solution. In life science, the most important liquid-solid interfaces are the water-cell-membrane interfaces. Phenomena occurring at the surface of phospholipid bilayers control the docking of proteins, the transmission of signals as well as transport of molecules in and out of the cell. Recently the development of bio-compatible materials has lead to research on the interface between bio-compatible material and lipid/proteins in aqueous solution. Gaining a microscopic insight into the processes occurring at liquid-solid interfaces is therefore fundamental to a wide range of disciplines. This special section collects some contributions to the CECAM Workshop 'Liquid/Solid interfaces: Structure and Dynamics from Spectroscopy and Simulations' which took place in Lausanne, Switzerland in June 2011. Our main aim was to bring together knowledge and expertise from different communities in order to advance our microscopic understanding of the structure and dynamics of liquids at interfaces. In particular, one of our ambitions was to foster discussion between the experimental and theoretical/computational communities. On the experimental side, surface specific techniques, such as non-linear optical spectroscopy (sum frequency generation spectroscopy (SFG) and second harmonic generation (SHG)), surface sensitive x-ray scattering, in situ scanning tunneling microscopy (STM) and infrared reflection absorption spectroscopy provide information on layers of nanometric thickness at the interface. On the other hand, it is quite clear that the experiments require theoretical modelling in order to dissect the experimental results and to rationalize the different factors that contribute to the interfacial properties. In this respect molecular dynamics simulations are a major tool. While many successes have already been achieved with molecular dynamics simulations based on empirical force fields, first principles molecular dynamics simulations are now emerging as the other major approach where structure and reactivity are treated in a consistent way. Recent progress within the past 3-5 years on efficient treatments of basis sets and long range interactions in density functional theory (DFT) indeed extend such simulation capabilities to hundreds and thousands of atoms, thus allowing realistic models for interfaces to be tackled, maintaining first principles quality. Most of these simulations bring information on the structural organization of the solvent in the interfacial region between the solid and the liquid, but very few investigate the supplementary challenge of extracting vibrational spectroscopic fingerprints of the interface and, in particular, the direct modeling of the vibrational sum frequency generation (VSFG) non-linear spectra. The present special section reports an interesting contribution from the group of R Y Shen who pioneered VSFG optical experiments. They show how VSFG measurements can be used to unravel the behavior of interfacial water on alumina Al2O3 as a function of pH. The groups of A Hodgson and C Busse respectively provide complementary experiments based on low energy electron diffraction (LEED), He atom scattering (HAS) and STM, to investigate the organization of water on metal, namely Pd(111) and Pt(111). Direct measurements of hyperpolarizabilities for non-linear spectroscopy can be made through hyper-Rayleigh scattering experiments, which are presented here by the group of P F Brevet on gold and silver nanoparticles. From the point of view of molecular dynamics simulations of interfaces, complementary levels of calculations are presented in this special section. The groups of K Leung, M-P Gaigeot, M Sulpizi and M Sprik provide theoretical investigations with DFT-based molecular dynamics simulations. Leung et al and Gaigeot et al address the hot topic issue of the reactivity of oxides surface sites and especially reliable methods to calculate pKas of these sites, with simulations taking into account both the solid and the liquid explicitly, and at the same first principles level of theory. Gaigeot, Sprik and Sulpizi furthermore combine the information on the structural organization of liquid water at the interface with quartz and alumina via pKa calculations and vibrational features (and their microscopic assignments). Mixed quantum/classical molecular dynamics (QM/MM) simulations are presented by Ishiyama and Morita for the investigation of another topical interface, i.e. the liquid-air interface. They provide the theoretical VSFG spectrum of the water-vapor interface and some understanding at the microscopic level of the experimental vibrational features. Molecular dynamics simulations based on empirical force fields have been applied to investigate hydrophobic interfaces by the groups of B Space and P Carloni. Carloni et al address salt effects at water-hydrophobic interfaces, investigating how the salts affect the structural organization of water at these interfaces. Space et al provide theoretical approximations to VSFG calculations in the special case of the carbon tetrachloride-water interface and the assignments of the experimental recorded signatures. 'More traditional' DFT static calculations can be applied to complex objects at interfaces, providing their vibrational spectra, and two papers in this special section illustrate such approaches. Ceccet et al extract first hyperpolarizability tensors from DFT calculations on aliphatic chains and simulate the related VSFG spectra. They also investigate the effect of different functionals on the final signatures. Liegeois et al investigate functionalized surfaces, mainly focusing on IR and Raman spectral features, and provide very precise vibrational assignments depending on chemisorption or physisorption of the adsorbed molecules. We are grateful to all the authors for their contributions to this special section and we hope that readers will enjoy this collection of papers and that they will find further motivation to investigate and understand the complex phenomena occurring at interfaces. Liquid-solid interfaces contents The interfacial structure of water/protonated α-Al2O3 (112¯0) as a function of pHJ Sung, Y R Shen and G A Waychunas Strain relief and disorder in commensurate water layers formed on Pd(111)F McBride, A Omer, C M Clay, L Cummings, G R Darling and A Hodgson H2O on Pt(111): structure and stability of the first wetting layer Sebastian Standop, Markus Morgenstern, Thomas Michely and Carsten Busse Effect of a thioalkane capping layer on the first hyperpolarizabilities of gold and silver nanoparticles Yara El Harfouch, Emmanuel Benichou, Franck Bertorelle, Isabelle Russier-Antoine, Christian Jonin, Noelle Lascoux and Pierre F Brevet Predicting the acidity constant of a goethite hydroxyl group from first principlesKevin Leung and Louise J Criscenti Oxide/water interfaces: how the surface chemistry modifies interfacial water properties Marie-Pierre Gaigeot, Michiel Sprik and Marialore Sulpizi Vibrational spectrum at a water surface: a hybrid quantum mechanics/molecular mechanics molecular dynamics approach Tatsuya Ishiyama, Hideaki Takahashi and Akihiro Morita A theoretical study of the sum frequency vibrational spectroscopy of the carbon tetrachloride/water interface Anthony J Green, Angela Perry, Preston B Moore and Brian Space Salt effects on water/hydrophobic liquid interfaces: a molecular dynamics study Chao Zhang and Paolo Carloni Density functional theory-based simulations of sum frequency generation spectra involving methyl stretching vibrations: effect of the molecular model on the deduced molecular orientation and comparison with an analytical approach F Cecchet, D Lis, Y Caudano, A A Mani, A Peremans, B Champagne and J Guthmuller Towards modelling the vibrational signatures of functionalized surfaces: carboxylic acids on H-Si(111) surfaces Conrard Giresse Tetsassi Feugmo, Benoît Champagne, Yves Caudano, Francesca Cecchet, Yves J Chabal and Vincent Liégeois

Bubble bursting at an interface

NASA Astrophysics Data System (ADS)

Kulkarni, Varun; Sajjad, Kumayl; Anand, Sushant; Fezzaa, Kamel

2017-11-01

Bubble bursting is crucial to understanding the life span of bubbles at an interface and more importantly the nature of interaction between the bulk liquid and the outside environment from the point of view of chemical and biological material transport. The dynamics of the bubble as it rises from inside the liquid bulk to its disappearance on the interface after bursting is an intriguing process, many aspects of which are still being explored. In our study, we make detailed high speed imaging measurements to examine carefully the hole initiation and growth in bursting bubbles that unearth some interesting features of the process. Previous analyses available in literature are revisited based on our novel experimental visualizations. Using a combination of experiments and theory we investigate the role of various forces during the rupturing process. This work aims to further our current knowledge of bubble dynamics at an interface with an aim of predicting better the bubble evolution from its growth to its eventual integration with the liquid bulk.

Layerless fabrication with continuous liquid interface production.

PubMed

Janusziewicz, Rima; Tumbleston, John R; Quintanilla, Adam L; Mecham, Sue J; DeSimone, Joseph M

2016-10-18

Despite the increasing popularity of 3D printing, also known as additive manufacturing (AM), the technique has not developed beyond the realm of rapid prototyping. This confinement of the field can be attributed to the inherent flaws of layer-by-layer printing and, in particular, anisotropic mechanical properties that depend on print direction, visible by the staircasing surface finish effect. Continuous liquid interface production (CLIP) is an alternative approach to AM that capitalizes on the fundamental principle of oxygen-inhibited photopolymerization to generate a continual liquid interface of uncured resin between the growing part and the exposure window. This interface eliminates the necessity of an iterative layer-by-layer process, allowing for continuous production. Herein we report the advantages of continuous production, specifically the fabrication of layerless parts. These advantages enable the fabrication of large overhangs without the use of supports, reduction of the staircasing effect without compromising fabrication time, and isotropic mechanical properties. Combined, these advantages result in multiple indicators of layerless and monolithic fabrication using CLIP technology.

Layerless fabrication with continuous liquid interface production

PubMed Central

Janusziewicz, Rima; Tumbleston, John R.; Quintanilla, Adam L.; Mecham, Sue J.; DeSimone, Joseph M.

2016-01-01

Despite the increasing popularity of 3D printing, also known as additive manufacturing (AM), the technique has not developed beyond the realm of rapid prototyping. This confinement of the field can be attributed to the inherent flaws of layer-by-layer printing and, in particular, anisotropic mechanical properties that depend on print direction, visible by the staircasing surface finish effect. Continuous liquid interface production (CLIP) is an alternative approach to AM that capitalizes on the fundamental principle of oxygen-inhibited photopolymerization to generate a continual liquid interface of uncured resin between the growing part and the exposure window. This interface eliminates the necessity of an iterative layer-by-layer process, allowing for continuous production. Herein we report the advantages of continuous production, specifically the fabrication of layerless parts. These advantages enable the fabrication of large overhangs without the use of supports, reduction of the staircasing effect without compromising fabrication time, and isotropic mechanical properties. Combined, these advantages result in multiple indicators of layerless and monolithic fabrication using CLIP technology. PMID:27671641

System for concentrating and analyzing particles suspended in a fluid

DOEpatents

Fiechtner, Gregory J [Bethesda, MD; Cummings, Eric B [Livermore, CA; Singh, Anup K [Danville, CA

2011-04-26

Disclosed is a device for separating and concentrating particles suspended in a fluid stream by using dielectrophoresis (DEP) to trap and/or deflect those particles as they migrate through a fluid channel. The method uses fluid channels designed to constrain a liquid flowing through it to uniform electrokinetic flow velocities. This behavior is achieved by connecting deep and shallow sections of channels, with the channel depth varying abruptly along an interface. By careful design of abrupt changes in specific permeability at the interface, an abrupt and spatially uniform change in electrokinetic force can be selected. Because these abrupt interfaces also cause a sharp gradient in applied electric fields, a DEP force also can be established along the interface. Depending on the complex conductivity of the suspended particles and the immersion liquid, the DEP force can controllably complement or oppose the local electrokinetic force transporting the fluid through the channel allowing for manipulation of particles suspended in the transporting liquid.

Apparatus and method for concentrating and filtering particles suspended in a fluid

DOEpatents

Fiechtner, Gregory J [Bethesda, MD; Cummings, Eric B [Livermore, CA; Singh, Anup K [Danville, CA

2009-05-19

Disclosed is a device for separating and concentrating particles suspended in a fluid stream by using dielectrophoresis (DEP) to trap and/or deflect those particles as they migrate through a fluid channel. The method uses fluid channels designed to constrain a liquid flowing through it to uniform electrokinetic flow velocities. This behavior is achieved by connecting deep and shallow sections of channels, with the channel depth varying abruptly along an interface. By careful design of abrupt changes in specific permeability at the interface, an abrupt and spatially uniform change in electrokinetic force can be selected. Because these abrupt interfaces also cause a sharp gradient in applied electric fields, a DEP force also can be established along the interface. Depending on the complex conductivity of the suspended particles and the immersion liquid, the DEP force can controllably complement or oppose the local electrokinetic force transporting the fluid through the channel allowing for manipulation of particles suspended in the transporting liquid.

The interfacial structure of water droplets in a hydrophobic liquid

NASA Astrophysics Data System (ADS)

Smolentsev, Nikolay; Smit, Wilbert J.; Bakker, Huib J.; Roke, Sylvie

2017-05-01

Nanoscopic and microscopic water droplets and ice crystals embedded in liquid hydrophobic surroundings are key components of aerosols, rocks, oil fields and the human body. The chemical properties of such droplets critically depend on the interfacial structure of the water droplet. Here we report the surface structure of 200 nm-sized water droplets in mixtures of hydrophobic oils and surfactants as obtained from vibrational sum frequency scattering measurements. The interface of a water droplet shows significantly stronger hydrogen bonds than the air/water or hexane/water interface and previously reported planar liquid hydrophobic/water interfaces at room temperature. The observed spectral difference is similar to that of a planar air/water surface at a temperature that is ~50 K lower. Supercooling the droplets to 263 K does not change the surface structure. Below the homogeneous ice nucleation temperature, a single vibrational mode is present with a similar mean hydrogen-bond strength as for a planar ice/air interface.

Effect of interfaces on the nearby Brownian motion.

PubMed

Huang, Kai; Szlufarska, Izabela

2015-10-06

Near-boundary Brownian motion is a classic hydrodynamic problem of great importance in a variety of fields, from biophysics to micro-/nanofluidics. However, owing to challenges in experimental measurements of near-boundary dynamics, the effect of interfaces on Brownian motion has remained elusive. Here we report a computational study of this effect using μs-long large-scale molecular dynamics simulations and our newly developed Green-Kubo relation for friction at the liquid-solid interface. Our computer experiment unambiguously reveals that the t(-3/2) long-time decay of the velocity autocorrelation function of a Brownian particle in bulk liquid is replaced by a t(-5/2) decay near a boundary. We discover a general breakdown of traditional no-slip boundary condition at short time scales and we show that this breakdown has a profound impact on the near-boundary Brownian motion. Our results demonstrate the potential of Brownian-particle-based micro-/nanosonar to probe the local wettability of liquid-solid interfaces.

Optical switch based on the electrically controlled liquid crystal interface.

PubMed

Komar, Andrei A; Tolstik, Alexei L; Melnikova, Elena A; Muravsky, Alexander A

2015-06-01

The peculiarities of the linearly polarized light beam reflection at the interface within the bulk of a nematic liquid crystal (NLC) cell with different orientations of the director are analyzed. Two methods to create the interface are considered. Combination of the planar and homeotropic orientations of the NLC director is realized by means of a spatially structured electrode under the applied voltage. In-plane patterned azimuthal alignment of the NLC director is created by the patterned rubbing alignment technique. All possible orthogonal orientations of the LC director are considered; the configurations for realization of total internal reflection are determined. The revealed relationship between the propagation of optical beams in a liquid crystal material and polarization of laser radiation has enabled realization of the spatial separation for the orthogonally polarized light beams at the interface between two regions of NLC with different director orientations (domains). Owing to variations in the applied voltage and, hence, in the refractive index gradient, the light beam propagation directions may be controlled electrically.

Dynamics and unsteady morphologies at ice interfaces driven by D2O–H2O exchange

PubMed Central

Holmes-Cerfon, Miranda; Kohn, Robert V.

2017-01-01

The growth dynamics of D2O ice in liquid H2O in a microfluidic device were investigated between the melting points of D2O ice (3.8 °C) and H2O ice (0 °C). As the temperature was decreased at rates between 0.002 °C/s and 0.1 °C/s, the ice front advanced but retreated immediately upon cessation of cooling, regardless of the temperature. This is a consequence of the competition between diffusion of H2O into the D2O ice, which favors melting of the interface, and the driving force for growth supplied by cooling. Raman microscopy tracked H/D exchange across the solid H2O–solid D2O interface, with diffusion coefficients consistent with transport of intact H2O molecules at the D2O ice interface. At fixed temperatures below 3 °C, the D2O ice front melted continuously, but at temperatures near 0 °C a scalloped interface morphology appeared with convex and concave sections that cycled between growth and retreat. This behavior, not observed for D2O ice in contact with D2O liquid or H2O ice in contact with H2O liquid, reflects a complex set of cooperative phenomena, including H/D exchange across the solid–liquid interface, latent heat exchange, local thermal gradients, and the Gibbs–Thomson effect on the melting points of the convex and concave features. PMID:29042511

Interactions Between Ocean Circulation and Topography in Icy Worlds

NASA Astrophysics Data System (ADS)

Goodman, J. C.

2018-05-01

To what extent does topography at the water-rock interface control the general circulation patterns of icy world oceans? And contrariwise, to what extent does liquid flow control the topography at the ice-water interface (or interfaces)?

Solid-liquid surface tensions of critical nuclei and nucleation barriers from a phase-field-crystal study of a model binary alloy using finite system sizes.

PubMed

Choudhary, Muhammad Ajmal; Kundin, Julia; Emmerich, Heike; Oettel, Martin

2014-08-01

Phase-field-crystal (PFC) modeling has emerged as a computationally efficient tool to address crystal growth phenomena on atomistic length and diffusive time scales. We use a two-dimensional phase-field-crystal model for a binary system based on Elder et al. [Phys. Rev. B 75, 064107 (2007)] to study critical nuclei and their liquid-solid phase boundaries, in particular the nucleus size dependence of the liquid-solid interface tension as well as of the nucleation barrier. Critical nuclei are stabilized in finite systems of various sizes, however, the extracted interface tension as function of the nucleus radius r is independent of system size. We suggest a phenomenological expression to describe the dependence of the extracted interface tension on the nucleus radius r for the liquid-solid system. Moreover, the numerical PFC results show that this dependency can not be fully described by the nonclassical Tolman formula.

Exploring parameter space effects on structure-property relationships of surfactants at liquid-liquid interfaces.

PubMed

Emborsky, Christopher P; Cox, Kenneth R; Chapman, Walter G

2011-08-28

The ubiquitous use of surfactants in commercial and industrial applications has led to many experimental, theoretical, and simulation based studies. These efforts seek to provide a molecular level understanding of the effects on structuring behavior and the corresponding impacts on observable properties (e.g., interfacial tension). With such physical detail, targeted system design can be improved over typical techniques of observational trends and phenomenological correlations by taking advantage of predictive system response. This research provides a systematic study of part of the broad parameter space effects on equilibrium microstructure and interfacial properties of amphiphiles at a liquid-liquid interface using the interfacial statistical associating fluid theory density functional theory as a molecular model for the system from the bulk to the interface. Insights into the molecular level physics and thermodynamics governing the system behavior are discussed as they relate to both predictions qualitatively consistent with experimental observations and extensions beyond currently available studies. © 2011 American Institute of Physics

Effect of dissolved LiCl on the ionic liquid-Au(111) interface: an in situ STM study

NASA Astrophysics Data System (ADS)

Borisenko, Natalia; Atkin, Rob; Lahiri, Abhishek; Zein El Abedin, Sherif; Endres, Frank

2014-07-01

The structure of the electrolyte/electrode interface plays a significant role in electrochemical processes. To date, most studies are focusing on understanding the interfacial structure in pure ionic liquids. In this paper in situ scanning tunnelling microscopy (STM) has been employed to elucidate the structure of the charged Au(111)-ionic liquid (1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate, [Py1,4]FAP) interface in the presence of 0.1 M LiCl. The addition of the Li salt to the ionic liquid has a strong influence on the interfacial structure. In the first STM scan in situ measurements reveal that Au(111) undergoes the (22 \\times \\surd 3) ‘herringbone’ reconstruction in a certain potential regime, and there is strong evidence that the gold surface dissolves at negative electrode potentials in [Py1,4]FAP containing LiCl. Bulk deposition of Li is obtained at -2.9 V in the second STM scan.

High thermal conductivity liquid metal pad for heat dissipation in electronic devices

NASA Astrophysics Data System (ADS)

Lin, Zuoye; Liu, Huiqiang; Li, Qiuguo; Liu, Han; Chu, Sheng; Yang, Yuhua; Chu, Guang

2018-05-01

Novel thermal interface materials using Ag-doped Ga-based liquid metal were proposed for heat dissipation of electronic packaging and precision equipment. On one hand, the viscosity and fluidity of liquid metal was controlled to prevent leakage; on the other hand, the thermal conductivity of the Ga-based liquid metal was increased up to 46 W/mK by incorporating Ag nanoparticles. A series of experiments were performed to evaluate the heat dissipation performance on a CPU of smart-phone. The results demonstrated that the Ag-doped Ga-based liquid metal pad can effectively decrease the CPU temperature and change the heat flow path inside the smart-phone. To understand the heat flow path from CPU to screen through the interface material, heat dissipation mechanism was simulated and discussed.

Research on the relation between the contact angle and the interface curvature radius of electrowetting liquid zoom lens

NASA Astrophysics Data System (ADS)

Zhao, Cunhua; Liang, Huiqin; Cui, Dongqing; Hong, Xinhua; Wei, Daling; Gao, Changliu

2011-08-01

In the ultralight or ultrathin applied domain of zoom lens, the traditional glass / plastic lens is limited for manufacture technology or cost. Therefore, a liquid lens was put forward to solve the problems. The liquid zoom lens has the merits of lower cost, smaller volume, quicker response, lower energy consumption, continuous zoom and higher accuracy. In liquid zoom lens the precise focal length is obtained by the contact angle changing to affect the curvature radius of interface. In our works, the relations of the exerted voltage, the contact angle, the curvature radius and the focal length were researched and accurately calculated. The calculation of the focal length provides an important theoretical basis for instructing the design of liquid zoom lens.

Coherent X-ray Scattering from Liquid-Air Interfaces

NASA Astrophysics Data System (ADS)

Shpyrko, Oleg

Advances in synchrotron x-ray scattering techniques allow studies of structure and dynamics of liquid surfaces with unprecedented resolution. I will review x-ray scattering measurements of thermally excited capillary fluctuations in liquids, thin polymer liquid films and polymer surfaces in confined geometry. X-ray Diffuse scattering profile due to Debye-Waller like roughening of the surface allows to probe the distribution of capillary fluctuations over a wide range of length scales, while using X-ray Photon Correlation Spectroscopy (XPCS) one is able to directly couple to nanoscale dynamics of these surface fluctuations, over a wide range of temporal and spacial scales. I will also discuss recent XPCS measurements of lateral diffusion dynamics in Langmuir monolayers assembled at the liquid-air interface. This research was supported by NSF CAREER Grant 0956131.

Copper phthalocyanine films deposited by liquid-liquid interface recrystallization technique (LLIRCT).

PubMed

Patil, K R; Sathaye, S D; Hawaldar, R; Sathe, B R; Mandale, A B; Mitra, A

2007-11-15

The simple recrystallization process is innovatively used to obtain the nanoparticles of copper phthalocyanine by a simple method. Liquid-liquid interface recrystallization technique (LLIRCT) has been employed successfully to produce small sized copper phthalocyanine nanoparticles with diameter between 3-5 nm. The TEM-SAED studies revealed the formation of 3-5 nm sized with beta-phase dominated mixture of alpha and beta copper phthalocyanine nanoparticles. The XRD, SEM, and the UV-vis studies were further carried out to confirm the formation of copper phthalocyanine thin films. The cyclic voltametry (CV) studies conclude that redox reaction is totally reversible one electron transfer process. The process is attributed to Cu(II)/Cu(I) redox reaction.

An approximate theoretical treatment of ion transfer processes at asymmetric microscopic and nanoscopic liquid-liquid interfaces: Single and double potential pulse techniques

NASA Astrophysics Data System (ADS)

Molina, A.; Laborda, E.; Compton, R. G.

2014-03-01

Simple theory for the electrochemical study of reversible ion transfer processes at micro- and nano-liquid|liquid interfaces supported on a capillary is presented. Closed-form expressions are obtained for the response in normal pulse and differential double pulse voltammetries, which describe adequately the particular behaviour of these systems due to the ‘asymmetric’ ion diffusion inside and outside the capillary. The use of different potential pulse techniques for the determination of the formal potential and diffusion coefficients of the ion is examined. For this, very simple analytical expressions are presented for the half-wave potential in NPV and the peak potential in DDPV.

Understanding the breakdown of classic two-phase theory and spray atomization at engine-relevant conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahms, Rainer N.

A generalized framework for multi-component liquid injections is presented to understand and predict the breakdown of classic two-phase theory and spray atomization at engine-relevant conditions. The analysis focuses on the thermodynamic structure and the immiscibility state of representative gas-liquid interfaces. The most modern form of Helmholtz energy mixture state equation is utilized which exhibits a unique and physically consistent behavior over the entire two-phase regime of fluid densities. It is combined with generalized models for non-linear gradient theory and for liquid injections to quantify multi-component two-phase interface structures in global thermal equilibrium. Then, the Helmholtz free energy is minimized whichmore » determines the interfacial species distribution as a consequence. This minimal free energy state is demonstrated to validate the underlying assumptions of classic two-phase theory and spray atomization. However, under certain engine-relevant conditions for which corroborating experimental data are presented, this requirement for interfacial thermal equilibrium becomes unsustainable. A rigorously derived probability density function quantifies the ability of the interface to develop internal spatial temperature gradients in the presence of significant temperature differences between injected liquid and ambient gas. Then, the interface can no longer be viewed as an isolated system at minimal free energy. Instead, the interfacial dynamics become intimately connected to those of the separated homogeneous phases. Hence, the interface transitions toward a state in local equilibrium whereupon it becomes a dense-fluid mixing layer. A new conceptual view of a transitional liquid injection process emerges from a transition time scale analysis. Close to the nozzle exit, the two-phase interface still remains largely intact and more classic two-phase processes prevail as a consequence. Further downstream, however, the transition to dense-fluid mixing generally occurs before the liquid length is reached. As a result, the significance of the presented modeling expressions is established by a direct comparison to a reduced model, which utilizes widely applied approximations but fundamentally fails to capture the physical complexity discussed in this paper.« less

Understanding the breakdown of classic two-phase theory and spray atomization at engine-relevant conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahms, Rainer N., E-mail: Rndahms@sandia.gov

A generalized framework for multi-component liquid injections is presented to understand and predict the breakdown of classic two-phase theory and spray atomization at engine-relevant conditions. The analysis focuses on the thermodynamic structure and the immiscibility state of representative gas-liquid interfaces. The most modern form of Helmholtz energy mixture state equation is utilized which exhibits a unique and physically consistent behavior over the entire two-phase regime of fluid densities. It is combined with generalized models for non-linear gradient theory and for liquid injections to quantify multi-component two-phase interface structures in global thermal equilibrium. Then, the Helmholtz free energy is minimized whichmore » determines the interfacial species distribution as a consequence. This minimal free energy state is demonstrated to validate the underlying assumptions of classic two-phase theory and spray atomization. However, under certain engine-relevant conditions for which corroborating experimental data are presented, this requirement for interfacial thermal equilibrium becomes unsustainable. A rigorously derived probability density function quantifies the ability of the interface to develop internal spatial temperature gradients in the presence of significant temperature differences between injected liquid and ambient gas. Then, the interface can no longer be viewed as an isolated system at minimal free energy. Instead, the interfacial dynamics become intimately connected to those of the separated homogeneous phases. Hence, the interface transitions toward a state in local equilibrium whereupon it becomes a dense-fluid mixing layer. A new conceptual view of a transitional liquid injection process emerges from a transition time scale analysis. Close to the nozzle exit, the two-phase interface still remains largely intact and more classic two-phase processes prevail as a consequence. Further downstream, however, the transition to dense-fluid mixing generally occurs before the liquid length is reached. The significance of the presented modeling expressions is established by a direct comparison to a reduced model, which utilizes widely applied approximations but fundamentally fails to capture the physical complexity discussed in this paper.« less

Understanding the breakdown of classic two-phase theory and spray atomization at engine-relevant conditions

DOE PAGES

Dahms, Rainer N.

2016-04-26

A generalized framework for multi-component liquid injections is presented to understand and predict the breakdown of classic two-phase theory and spray atomization at engine-relevant conditions. The analysis focuses on the thermodynamic structure and the immiscibility state of representative gas-liquid interfaces. The most modern form of Helmholtz energy mixture state equation is utilized which exhibits a unique and physically consistent behavior over the entire two-phase regime of fluid densities. It is combined with generalized models for non-linear gradient theory and for liquid injections to quantify multi-component two-phase interface structures in global thermal equilibrium. Then, the Helmholtz free energy is minimized whichmore » determines the interfacial species distribution as a consequence. This minimal free energy state is demonstrated to validate the underlying assumptions of classic two-phase theory and spray atomization. However, under certain engine-relevant conditions for which corroborating experimental data are presented, this requirement for interfacial thermal equilibrium becomes unsustainable. A rigorously derived probability density function quantifies the ability of the interface to develop internal spatial temperature gradients in the presence of significant temperature differences between injected liquid and ambient gas. Then, the interface can no longer be viewed as an isolated system at minimal free energy. Instead, the interfacial dynamics become intimately connected to those of the separated homogeneous phases. Hence, the interface transitions toward a state in local equilibrium whereupon it becomes a dense-fluid mixing layer. A new conceptual view of a transitional liquid injection process emerges from a transition time scale analysis. Close to the nozzle exit, the two-phase interface still remains largely intact and more classic two-phase processes prevail as a consequence. Further downstream, however, the transition to dense-fluid mixing generally occurs before the liquid length is reached. As a result, the significance of the presented modeling expressions is established by a direct comparison to a reduced model, which utilizes widely applied approximations but fundamentally fails to capture the physical complexity discussed in this paper.« less

Nanoparticles in liquid crystals, and liquid crystals in nanoparticles

NASA Astrophysics Data System (ADS)

de Pablo, Juan

2015-03-01

Liquid crystals are remarkably sensitive to interfacial interactions. Small perturbations at a liquid crystal interface, for example, can be propagated over relatively long length scales, thereby providing the basis for a wide range of applications that rely on amplification of molecular events into macroscopic observables. Our recent research efforts have focused on the reverse phenomenon; that is, we have sought to manipulate the interfacial assembly of nanoparticles or the organization of surface active molecules by controlling the structure of a liquid crystal. This presentation will consist of a review of the basic principles that are responsible for liquid crystal-mediated interactions, followed by demonstrations of those principles in the context of two types of systems. In the first, a liquid crystal is used to direct the assembly of nanoparticles; through a combination of molecular and continuum models, it is found that minute changes in interfacial energy and particle size lead to liquid-crystal induced attractions that can span multiple orders of magnitude. Theoretical predictions are confirmed by experimental observations, which also suggest that LC-mediated assembly provides an effective means for fabrication of plasmonic devices. In the second type of system, the structure of a liquid crystal is controlled by confinement in submicron droplets. The morphology of the liquid crystal in a drop depends on a delicate balance between bulk and interfacial contributions to the free energy; that balance can be easily perturbed by adsorption of analytes or nanoparticles at the interface, thereby providing the basis for development of hierarchical assembly of responsive, anisotropic materials. Theoretical predictions also indicate that the three-dimensional order of a liquid crystal can be projected onto a two-dimensional interface, and give rise to novel nanostructures that are not found in simple isotropic fluids.

Confined methane-water interfacial layers and thickness measurements using in situ Raman spectroscopy.

PubMed

Pinho, Bruno; Liu, Yukun; Rizkin, Benjamin; Hartman, Ryan L

2017-11-07

Gas-liquid interfaces broadly impact our planet, yet confined interfaces behave differently than unconfined ones. We report the role of tangential fluid motion in confined methane-water interfaces. The interfaces are created using microfluidics and investigated by in situ 1D, 2D and 3D Raman spectroscopy. The apparent CH 4 and H 2 O concentrations are reported for Reynolds numbers (Re), ranging from 0.17 to 8.55. Remarkably, the interfaces are comprised of distinct layers of thicknesses varying from 23 to 57 μm. We found that rarefaction, mixture, thin film, and shockwave layers together form the interfaces. The results indicate that the mixture layer thickness (δ) increases with Re (δ ∝ Re), and traditional transport theory for unconfined interfaces does not explain the confined interfaces. A comparison of our results with thin film theory of air-water interfaces (from mass transfer experiments in capillary microfluidics) supports that the hydrophobicity of CH 4 could decrease the strength of water-water interactions, resulting in larger interfacial thicknesses. Our findings help explain molecular transport in confined gas-liquid interfaces, which are common in a broad range of societal applications.

Liquid-liquid extraction assisted by a carbon nanoparticles interface. Electrophoretic determination of atrazine in environmental samples.

PubMed

Caballero-Díaz, Encarnación; Simonet, Bartolomé; Valcárcel, Miguel

2013-10-21

A novel method for the determination of atrazine, using liquid-liquid extraction assisted by a nanoparticles film formed in situ and composed of organic solvent stabilized-carbon nanoparticles, is described. The presence of nanoparticles located at the liquid-liquid interface reinforced the extraction of analyte from matrix prior to capillary electrophoresis (CE) analysis. Some influential experimental variables were optimized in order to enhance the extraction efficiency. The developed procedure confirmed that carbon nanoparticles, especially multi-walled carbon nanotubes, are suitable to be used in sample treatment processes introducing new mechanisms of interaction with the analyte. The application of the proposed preconcentration method followed by CE detection enabled the determination of atrazine in spiked river water providing acceptable RSD values (11.6%) and good recoveries (about 87.0-92.0%). Additionally, a similar extraction scheme was tested in soil matrices with a view to further applications in real soil samples.

A novel X-ray diffractometer for studies of liquid-liquid interfaces.

PubMed

Murphy, Bridget M; Greve, Matthais; Runge, Benjamin; Koops, Christian T; Elsen, Annika; Stettner, Jochim; Seeck, Oliver H; Magnussen, Olaf M

2014-01-01

The study of liquid-liquid interfaces with X-ray scattering methods requires special instrumental considerations. A dedicated liquid surface diffractometer employing a tilting double-crystal monochromator in Bragg geometry has been designed. This diffractometer allows reflectivity and grazing-incidence scattering measurements of an immobile mechanically completely decoupled liquid sample, providing high mechanical stability. The available energy range is from 6.4 to 29.4 keV, covering many important absorption edges. The instrument provides access in momentum space out to 2.54 Å(-1) in the surface normal and out to 14.8 Å(-1) in the in-plane direction at 29.4 keV. Owing to its modular design the diffractometer is also suitable for heavy apparatus such as vacuum chambers. The instrument performance is described and examples of X-ray reflectivity studies performed under in situ electrochemical control and on biochemical model systems are given.

Numerical study of effect of the gas-coolant free surface on the droplet fragmentation behavior of coolants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, H.X.; Anh, B.V.; Dinh, T.N.

1999-07-01

This paper presents results of a numerical investigation on the behavior of melt drops falling in a gas (vapor) space and then penetrating into a liquid volume through the gas-liquid interface. The phenomenon studied here is, usually, observed when a liquid drop falls through air into a water pool and is, specially, of interest when a hypothetical severe reactor core meltdown accident is considered. The objective of this work is to study the effect of the gas-liquid interface on the dynamic evolution of the interaction area between the fragmenting melt drop and water. In the present study, the Navier-Stokes equationsmore » are solved for three phases (gas, liquid and melt-drop) using a higher-order, explicit, numerical method, called Cubic-Interpolated Pseudo-Particle (CIP) method, which is employed in combination with an advanced front-capturing scheme, named the Level Set Algorithm (LSA). By using this method, reasonable physical pictures of droplet deformation and fragmentation during movement in a stationary uniform water pool, and in a gas-liquid two-layer volume, is simulated. Effect of the gas-liquid interface on the drop deformation and fragmentation is analyzed by comparing the simulation results obtained for the two cases. Effects of the drop geometry, and of the flow conditions, on the behavior of the melt drop are also analyzed.« less

Fine-Tuning Nanoparticle Packing at Water-Oil Interfaces Using Ionic Strength.

PubMed

Chai, Yu; Lukito, Alysia; Jiang, Yufeng; Ashby, Paul D; Russell, Thomas P

2017-10-11

Nanoparticle-surfactants (NPSs) assembled at water-oil interfaces can significantly lower the interfacial tension and can be used to stabilize liquids. Knowing the formation and assembly and actively tuning the packing of these NPSs is of significant fundamental interest for the interfacial behavior of nanoparticles and of interest for water purification, drug encapsulation, enhanced oil recovery, and innovative energy transduction applications. Here, we demonstrate by means of interfacial tension measurements the high ionic strength helps the adsorption of NPSs to the water-oil interface leading to a denser packing of NPSs at the interface. With the reduction of interfacial area, the phase transitions from a "gas"-like to "liquid" to "solid" states of NPSs in two dimensions are observed. Finally, we provide the first in situ real-space imaging of NPSs at the water-oil interface by atomic force microcopy.

The Unfortunate Human Factor: A Selective History of Human Factors for Technical Communicators.

ERIC Educational Resources Information Center

Johnson, Robert R.

1994-01-01

Reviews moments in the history of human factors that are especially relevant to the field of technical communications. Discusses human factors research that is applicable to technical communications. Focuses on qualitative usability research, minimalism, and human activity interface design. (HB)

Film bonded fuel cell interface configuration

DOEpatents

Kaufman, Arthur; Terry, Peter L.

1985-01-01

An improved interface configuration for use between adjacent elements of a fuel cell stack. The interface is impervious to gas and liquid and provides resistance to corrosion by the electrolyte of the fuel cell. A multi-layer arrangement for the interface provides bridging electrical contact with a hot-pressed resin filling the void space.

Process for making film-bonded fuel cell interfaces

DOEpatents

Kaufman, Arthur; Terry, Peter L.

1990-07-03

An improved interface configuration for use between adjacent elements of a fuel cell stack. The interface is impervious to gas and liquid and provides resistance to corrosion by the electrolyte of the fuel cell. A multi-layer arrangement for the interface provides bridging electrical contact with a hot-pressed resin filling the void space.

Near Axisymmetric Partial Wetting Using Interface-Localized Liquid Dielectrophoresis.

PubMed

Brabcova, Zuzana; McHale, Glen; Wells, Gary G; Brown, Carl V; Newton, Michael I; Edwards, Andrew M J

2016-10-25

The wetting of solid surfaces can be modified by altering the surface free energy balance between the solid, liquid, and vapor phases. Liquid dielectrophoresis (L-DEP) can produce wetting on normally nonwetting surfaces, without modification of the surface topography or chemistry. L-DEP is a bulk force acting on the dipoles of a dielectric liquid and is not normally considered to be a localized effect acting at the interface between the liquid and a solid or other fluid. However, if this force is induced by a nonuniform electric field across a solid-liquid interface, it can be used to enhance and control the wetting of a dielectric liquid. Recently, it was reported theoretically and experimentally that this approach can cause a droplet of oil to spread along parallel interdigitated electrodes thus forming a stripe of liquid. Here we show that by using spiral-shaped electrodes actuated with four 90° successive phase-shifted signals, a near axisymmetric spreading of droplets can be achieved. Experimental observations show that the induced wetting can achieve film formation, an effect not possible with electrowetting. We show that the spreading is reversible thus enabling a wide range of partial wetting droplet states to be achieved in a controllable manner. Furthermore, we find that the cosine of the contact angle has a quadratic dependence on applied voltage during spreading and deduce a scaling law for the dependence of the strength of the effect on the electrode size.

Sheath liquid interface for the coupling of normal-phase liquid chromatography with electrospray mass spectrometry and its application to the analysis of neoflavonoids.

PubMed

Charles, Laurence; Laure, Frédéric; Raharivelomanana, Phila; Bianchini, Jean-Pierre

2005-01-01

A novel interface that allows normal-phase liquid chromatography to be coupled with electrospray ionization (ESI) is reported. A make-up solution of 60 mM ammonium acetate in methanol, infused at a 5 microl min(-1) flow-rate at the tip of the electrospray probe, provides a sheath liquid which is poorly miscible with the chromatographic effluent, but promotes efficient ionization of the targeted analytes. Protonated molecules generated in the ESI source were subjected to tandem mass spectrometric experiments in a triple-quadrupole mass spectrometer. The main fragmentation reactions were characterized for each analyte and specific mass spectral transitions were used to acquire chromatographic data in the multiple reaction monitoring detection mode. Results obtained during optimization of the sheath liquid composition and flow-rate suggest that the electrospray process was mainly under the control of the make-up solution, and that it forms an external charged layer around a neutral chromatographic mobile phase core. This sheath liquid interface was implemented for the analysis of some neoflavonoid compounds and its performance was evaluated. Limits of detection were established for calophillolide, inophyllum B, inophyllum P and inophyllum C at 100, 25, 15 and 100 ng ml(-1), respectively.

Surface structure evolution in a homologous series of ionic liquids.

PubMed

Haddad, Julia; Pontoni, Diego; Murphy, Bridget M; Festersen, Sven; Runge, Benjamin; Magnussen, Olaf M; Steinrück, Hans-Georg; Reichert, Harald; Ocko, Benjamin M; Deutsch, Moshe

2018-02-06

Interfaces of room temperature ionic liquids (RTILs) are important for both applications and basic science and are therefore intensely studied. However, the evolution of their interface structure with the cation's alkyl chain length [Formula: see text] from Coulomb to van der Waals interaction domination has not yet been studied for even a single broad homologous RTIL series. We present here such a study of the liquid-air interface for [Formula: see text], using angstrom-resolution X-ray methods. For [Formula: see text], a typical "simple liquid" monotonic surface-normal electron density profile [Formula: see text] is obtained, like those of water and organic solvents. For [Formula: see text], increasingly more pronounced nanoscale self-segregation of the molecules' charged moieties and apolar chains yields surface layering with alternating regions of headgroups and chains. The layering decays into the bulk over a few, to a few tens, of nanometers. The layering periods and decay lengths, their linear [Formula: see text] dependence, and slopes are discussed within two models, one with partial-chain interdigitation and the other with liquid-like chains. No surface-parallel long-range order is found within the surface layer. For [Formula: see text], a different surface phase is observed above melting. Our results also impact general liquid-phase issues like supramolecular self-aggregation and bulk-surface structure relations.

On the transition between two-phase and single-phase interface dynamics in multicomponent fluids at supercritical pressures

NASA Astrophysics Data System (ADS)

Dahms, Rainer N.; Oefelein, Joseph C.

2013-09-01

A theory that explains the operating pressures where liquid injection processes transition from exhibiting classical two-phase spray atomization phenomena to single-phase diffusion-dominated mixing is presented. Imaging from a variety of experiments have long shown that under certain conditions, typically when the pressure of the working fluid exceeds the thermodynamic critical pressure of the liquid phase, the presence of discrete two-phase flow processes become diminished. Instead, the classical gas-liquid interface is replaced by diffusion-dominated mixing. When and how this transition occurs, however, is not well understood. Modern theory still lacks a physically based model to quantify this transition and the precise mechanisms that lead to it. In this paper, we derive a new model that explains how the transition occurs in multicomponent fluids and present a detailed analysis to quantify it. The model applies a detailed property evaluation scheme based on a modified 32-term Benedict-Webb-Rubin equation of state that accounts for the relevant real-fluid thermodynamic and transport properties of the multicomponent system. This framework is combined with Linear Gradient Theory, which describes the detailed molecular structure of the vapor-liquid interface region. Our analysis reveals that the two-phase interface breaks down not necessarily due to vanishing surface tension forces, but due to thickened interfaces at high subcritical temperatures coupled with an inherent reduction of the mean free molecular path. At a certain point, the combination of reduced surface tension, the thicker interface, and reduced mean free molecular path enter the continuum length scale regime. When this occurs, inter-molecular forces approach that of the multicomponent continuum where transport processes dominate across the interfacial region. This leads to a continuous phase transition from compressed liquid to supercritical mixture states. Based on this theory, a regime diagram for liquid injection is developed that quantifies the conditions under which classical sprays transition to dense-fluid jets. It is shown that the chamber pressure required to support diffusion-dominated mixing dynamics depends on the composition and temperature of the injected liquid and ambient gas. To illustrate the method and analysis, we use conditions typical of diesel engine injection. We also present a companion set of high-speed images to provide experimental validation of the presented theory. The basic theory is quite general and applies to a wide range of modern propulsion and power systems such as liquid rockets, gas turbines, and reciprocating engines. Interestingly, the regime diagram associated with diesel engine injection suggests that classical spray phenomena at typical injection conditions do not occur.

Eddy current sensor concepts for the Bridgman growth of semiconductors

NASA Astrophysics Data System (ADS)

Dharmasena, Kumar P.; Wadley, Haydn N. G.

1997-03-01

Electromagnetic finite element methods have been used to identify eddy current sensor designs for monitoring CdTe vertical Bridgman crystal growth. A model system consisting of pairs of silicon cylinders with electrical conductivities similar to those of solid and liquid CdTe has been used to evaluate the multifrequency response of several sensors designed for locating and characterizing the curvature of liquid-solid interfaces during vertical Bridgman growth. At intermediate frequencies (100-800 kHz), the sensor's imaginary impedance monotonically increases as interfacial curvature changes from concave to convex or the interface location moves upwards through the sensor. The experimental data are in excellent agreement with theoretical predictions. At higher test frequencies (˜ 5 MHz), the test circuit's parasitics contribute to the sensor's response. Even so, the predicted trends with interface location/curvature were found to be still preserved, and the experiments confirm that the sensor's high frequency response depends more on interface location and has only a small sensitivity to curvature. Multifrequency data obtained from these types of sensors have the potential to separately discriminate the location and the shape of liquid-solid interfaces during the vertical Bridgman growth of CdTe and other semiconductor materials of higher electrical conductivity.

Crustal fingering: solidification on a viscously unstable interface

NASA Astrophysics Data System (ADS)

Fu, Xiaojing; Jimenez-Martinez, Joaquin; Cueto-Felgueroso, Luis; Porter, Mark; Juanes, Ruben

2017-11-01

Motivated by the formation of gas hydrates in seafloor sediments, here we study the volumetric expansion of a less viscous gas pocket into a more viscous liquid when the gas-liquid interfaces readily solidify due to hydrate formation. We first present a high-pressure microfluidic experiment to study the depressurization-controlled expansion of a Xenon gas pocket in a water-filled Hele-Shaw cell. The evolution of the pocket is controlled by three processes: (1) volumetric expansion of the gas; (2) rupturing of existing hydrate films on the gas-liquid interface; and (3) formation of new hydrate films. These result in gas fingering leading to a complex labyrinth pattern. To reproduce these observations, we propose a phase-field model that describes the formation of hydrate shell on viscously unstable interfaces. We design the free energy of the three-phase system to rigorously account for interfacial effects, gas compressibility and phase transitions. We model the hydrate shell as a highly viscous fluid with shear-thinning rheology to reproduce shell-rupturing behavior. We present high-resolution numerical simulations of the model, which illustrate the emergence of complex crustal fingering patterns as a result of gas expansion dynamics modulated by hydrate growth at the interface.

Influence of adhesion on aerobic biodegradation and bioremediation of liquid hydrocarbons.

PubMed

Abbasnezhad, Hassan; Gray, Murray; Foght, Julia M

2011-11-01

Biodegradation of poorly water-soluble liquid hydrocarbons is often limited by low availability of the substrate to microbes. Adhesion of microorganisms to an oil-water interface can enhance this availability, whereas detaching cells from the interface can reduce the rate of biodegradation. The capability of microbes to adhere to the interface is not limited to hydrocarbon degraders, nor is it the only mechanism to enable rapid uptake of hydrocarbons, but it represents a common strategy. This review of the literature indicates that microbial adhesion can benefit growth on and biodegradation of very poorly water-soluble hydrocarbons such as n-alkanes and large polycyclic aromatic hydrocarbons dissolved in a non-aqueous phase. Adhesion is particularly important when the hydrocarbons are not emulsified, giving limited interfacial area between the two liquid phases. When mixed communities are involved in biodegradation, the ability of cells to adhere to the interface can enable selective growth and enhance bioremediation with time. The critical challenge in understanding the relationship between growth rate and biodegradation rate for adherent bacteria is to accurately measure and observe the population that resides at the interface of the hydrocarbon phase. © Springer-Verlag 2011

Low-Dimensional Materials for Optoelectronic and Bioelectronic Applications

NASA Astrophysics Data System (ADS)

Hong, Tu

In this thesis, we first discuss the fundamentals of ab initio electronic structure theory and density functional theory (DFT). We also discuss statistics related to computing thermodynamic averages of molecular dynamics (MD). We then use this theory to analyze and compare the structural, dynamical, and electronic properties of liquid water next to prototypical metals including platinum, graphite, and graphene. Our results are built on Born-Oppenheimer molecular dynamics (BOMD) generated using density functional theory (DFT) which explicitly include van der Waals (vdW) interactions within a first principles approach. All calculations reported use large simulation cells, allowing for an accurate treatment of the water-electrode interfaces. We have included vdW interactions through the use of the optB86b-vdW exchange correlation functional. Comparisons with the Perdew-Burke-Ernzerhof (PBE) exchange correlation functional are also shown. We find an initial peak, due to chemisorption, in the density profile of the liquid water-Pt interface not seen in the liquid water-graphite interface, liquid watergraphene interface, nor interfaces studied previously. To further investigate this chemisorption peak, we also report differences in the electronic structure of single water molecules on both Pt and graphite surfaces. We find that a covalent bond forms between the single water molecule and the platinum surface, but not between the single water molecule and the graphite surface. We also discuss the effects that defects and dopants in the graphite and graphene surfaces have on the structure and dynamics of liquid water. Lastly, we introduce artificial neural networks (ANNs), and demonstrate how they can be used to machine learn electronic structure calculations. As a proof of principle, we show the success of an ANN potential energy surfaces for a dimer molecule with a Lennard-Jones potential.

Interface morphology studies of liquid phase epitaxy grown HgCdTe films by atomic force microscopy

NASA Astrophysics Data System (ADS)

Azoulay, M.; George, M. A.; Burger, A.; Collins, W. E.; Silberman, E.

1994-04-01

In this paper we report an investigation of the morphology of the interfaces of liquid phase epitaxy (LPE) grown HgCdTe thin films on CdTe and CdZnTe substrates by atomic force microscopy (AFM) on freshly cleaved (110) crystallographic planes. An empirical observation which may be linked to lattice mismatch was indicated by an angle between the cleavage steps of the substrate to those of the film. The precipitates with size ranging from 5 nm to 20 nm were found to be most apparent near the interface.

[Ambient air interference in oxygen intake measurements in liquid incubating media with the use of open polarographic cells].

PubMed

Miniaev, M V; Voronchikhina, L I

2007-01-01

A model of oxygen intake by aerobic bio-objects in liquid incubating media was applied to investigate the influence air-media interface area on accuracy of measuring the oxygen intake and error value. It was shown that intrusion of air oxygen increases the relative error to 24% in open polarographic cells and to 13% in cells with a reduced interface area. Results of modeling passive media oxygenation laid a basis for proposing a method to reduce relative error by 66% for open cells and by 15% for cells with a reduced interface area.

Exceptionally Slow Movement of Gold Nanoparticles at a Solid/Liquid Interface Investigated by Scanning Transmission Electron Microscopy.

PubMed

Verch, Andreas; Pfaff, Marina; de Jonge, Niels

2015-06-30

Gold nanoparticles were observed to move at a liquid/solid interface 3 orders of magnitude slower than expected for the movement in a bulk liquid by Brownian motion. The nanoscale movement was studied with scanning transmission electron microscopy (STEM) using a liquid enclosure consisting of microchips with silicon nitride windows. The experiments involved a variation of the electron dose, the coating of the nanoparticles, the surface charge of the enclosing membrane, the viscosity, and the liquid thickness. The observed slow movement was not a result of hydrodynamic hindrance near a wall but instead explained by the presence of a layer of ordered liquid exhibiting a viscosity 5 orders of magnitude larger than a bulk liquid. The increased viscosity presumably led to a dramatic slowdown of the movement. The layer was formed as a result of the surface charge of the silicon nitride windows. The exceptionally slow motion is a crucial aspect of electron microscopy of specimens in liquid, enabling a direct observation of the movement and agglomeration of nanoscale objects in liquid.

Henry Taube and Coordination Chemistry

Science.gov Websites

Shifts Caused by Cr++ in Aqueous Solutions, DOE Technical Report, 1962 Reactions of Solvated Ions Final Report, DOE Technical Report, 1962 Isotopic Discrimination of Some Solutes in Liquid Ammonia, DOE Technical Report, 1966 Final Technical Report of Research, DOE Technical Report, 1972 Top Additional Web

Microfluidic ultralow interfacial tensiometry with magnetic particles.

PubMed

Tsai, Scott S H; Wexler, Jason S; Wan, Jiandi; Stone, Howard A

2013-01-07

We describe a technique that measures ultralow interfacial tensions using paramagnetic spheres in a co-flow microfluidic device designed with a magnetic section. Our method involves tuning the distance between the co-flowing interface and the magnet's center, and observing the behavior of the spheres as they approach the liquid-liquid interface-the particles either pass through or are trapped by the interface. Using threshold values of the magnet-to-interface distance, we make estimates of the two-fluid interfacial tension. We demonstrate the effectiveness of this technique for measuring very low interfacial tensions, O(10(-6)-10(-5)) N m(-1), by testing solutions of different surfactant concentrations, and we show that our results are comparable with measurements made using a spinning drop tensiometer.

Hyperbolic Interfaces

NASA Astrophysics Data System (ADS)

Giomi, Luca

2012-09-01

Fluid interfaces, such as soap films, liquid droplets, or lipid membranes, are known to give rise to several special geometries, whose complexity and beauty continue to fascinate us, as observers of the natural world, and challenge us as scientists. Here I show that a special class of surfaces of constant negative Gaussian curvature can be obtained in fluid interfaces equipped with an orientational ordered phase. These arise in various soft and biological materials, such as nematic liquid crystals, cytoskeletal assemblies, or hexatic colloidal suspensions. The purely hyperbolic morphology originates from the competition between surface tension, that reduces the area of the interface at the expense of increasing its Gaussian curvature, and the orientational elasticity of the ordered phase, that in turn suffers for the distortion induced by the underlying curvature.

A three-dimensional phase field model for nanowire growth by the vapor-liquid-solid mechanism

NASA Astrophysics Data System (ADS)

Wang, Yanming; Ryu, Seunghwa; McIntyre, Paul C.; Cai, Wei

2014-07-01

We present a three-dimensional multi-phase field model for catalyzed nanowire (NW) growth by the vapor-liquid-solid (VLS) mechanism. The equation of motion contains both a Ginzburg-Landau term for deposition and a diffusion (Cahn-Hilliard) term for interface relaxation without deposition. Direct deposition from vapor to solid, which competes with NW crystal growth through the molten catalyst droplet, is suppressed by assigning a very small kinetic coefficient at the solid-vapor interface. The thermodynamic self-consistency of the model is demonstrated by its ability to reproduce the equilibrium contact angles at the VLS junction. The incorporation of orientation dependent gradient energy leads to faceting of the solid-liquid and solid-vapor interfaces. The model successfully captures the curved shape of the NW base and the Gibbs-Thomson effect on growth velocity.

Isomerization reaction dynamics and equilibrium at the liquid-vapor interface of water. A molecular-dynamics study

NASA Technical Reports Server (NTRS)

Benjamin, Ilan; Pohorille, Andrew

1993-01-01

The gauche-trans isomerization reaction of 1,2-dichloroethane at the liquid-vapor interface of water is studied using molecular-dynamics computer simulations. The solvent bulk and surface effects on the torsional potential of mean force and on barrier recrossing dynamics are computed. The isomerization reaction involves a large change in the electric dipole moment, and as a result the trans/gauche ratio is considerably affected by the transition from the bulk solvent to the surface. Reactive flux correlation function calculations of the reaction rate reveal that deviation from the transition-state theory due to barrier recrossing is greater at the surface than in the bulk water. This suggests that the system exhibits non-Rice-Ramsperger-Kassel-Marcus behavior due to the weak solvent-solute coupling at the water liquid-vapor interface.

Electrowetting-actuated optical switch based on total internal reflection.

PubMed

Liu, Chao; Wang, Di; Yao, Li-Xiao; Li, Lei; Wang, Qiong-Hua

2015-04-01

In this paper we demonstrate a liquid optical switch based on total internal reflection. Two indium tin oxide electrodes are fabricated on the bottom substrate. A conductive liquid (Liquid 1) is placed on one side of the chamber and surrounded by a density-matched silicone oil (Liquid 2). In initial state, when the light beam illuminates the interface of the two liquids, it just meets the conditions of total internal reflection. The light is totally reflected by Liquid 2, and the device shows light-off state. When we apply a voltage to the other side of the indium tin oxide electrode, Liquid 1 stretched towards this side of the substrate and the curvature of the liquid-liquid interface changes. The light beam is refracted by Liquid 1 and the device shows light-on state. So the device can achieve the functions of an optical switch. Because the light beam can be totally reflected by the liquid, the device can attain 100% light intensity attenuation. Our experiments show that the response time from light-on (off) to light-off (on) are 130 and 132 ms, respectively. The proposed optical switch has potential applications in variable optical attenuators, information displays, and light shutters.

Boiler for generating high quality vapor

NASA Technical Reports Server (NTRS)

Gray, V. H.; Marto, P. J.; Joslyn, A. W.

1972-01-01

Boiler supplies vapor for use in turbines by imparting a high angular velocity to the liquid annulus in heated rotating drum. Drum boiler provides a sharp interface between boiling liquid and vapor, thereby, inhibiting the formation of unwanted liquid droplets.

Evaporation thermal anslysis of Swallow-tailed Axial-grooved Heat Pipe

NASA Astrophysics Data System (ADS)

Zhang, Renping

2018-03-01

A detailed mathematical model that describes evaporating characteristics through thin liquid film at the evaporator section of swallow-tailed axial-grooved heat pipe was developed. The numerical simulation results about thin film profile, liquid-vapour interface temperature, evaporating rate and heat flux at the evaporating thin film region were given by the current investigation and the effect of superheat on the liquid-vapour interface temperature, evaporating mass rate and heat flux was discussed. Meanwhile, thermal model of the meniscus region at the evaporating section was developed to calculate the rate of heat transfer. The ratio of the heat conduction in the evaporating thin liquid film region and total heat rate were also discussed. It is indicated that the thickness of thin liquid film rises in a nearly linear fashion. The disjoining pressure can be neglected with increasing the liquid film thickness, tends to be negligibly small. The heat transfer rate at the intrinsic meniscus cannot be compared with that of the evaporating liquid film region.

Behavior of fluids in a weightless environment

NASA Technical Reports Server (NTRS)

Fester, D. A.; Eberhardt, R. N.; Tegart, J. R.

1977-01-01

Fluid behavior in a low-g environment is controlled primarily by surface tension forces. Certain fluid and system characteristics determine the magnitude of these forces for both a free liquid surface and liquid in contact with a solid. These characteristics, including surface tension, wettability or contact angle, system geometry, and the relationships governing their interaction, are discussed. Various aspects of fluid behavior in a low-g environment are then presented. This includes the formation of static interface shapes, oscillation and rotation of drops, coalescence, the formation of foams, tendency for cavitation, and diffusion in liquids which were observed during the Skylab fluid mechanics science demonstrations. Liquid reorientation and capillary pumping to establish equilibrium configurations for various system geometries, observed during various free-fall (drop-tower) low-g tests, are also presented. Several passive low-g fluid storage and transfer systems are discussed. These systems use surface tension forces to control the liquid/vapor interface and provide gas-free liquid transfer and liquid-free vapor venting.

Controlled gas-liquid interfacial plasmas for synthesis of nano-bio-carbon conjugate materials

NASA Astrophysics Data System (ADS)

Kaneko, Toshiro; Hatakeyama, Rikizo

2018-01-01

Plasmas generated in contact with a liquid have been recognized to be a novel reactive field in nano-bio-carbon conjugate creation because several new chemical reactions have been yielded at the gas-liquid interface, which were induced by the physical dynamics of non-equilibrium plasmas. One is the ion irradiation to a liquid, which caused the spatially selective dissociation of the liquid and the generation of additive reducing and oxidizing agents, resulting in the spatially controlled synthesis of nanostructures. The other is the electron irradiation to a liquid, which directly enhanced the reduction action at the plasma-liquid interface, resulting in temporally controlled nanomaterial synthesis. Using this novel reaction field, gold nanoparticles with controlled interparticle distance were synthesized using carbon nanotubes as a template. Furthermore, nanoparticle-biomolecule conjugates and nanocarbon-biomolecule conjugates were successfully synthesized by an aqueous-solution contact plasma and an electrolyte plasma, respectively, which were rapid and low-damage processes suitable for nano-bio-carbon conjugate materials.

Mixing and transient interface condensation of a liquid hydrogen tank

NASA Technical Reports Server (NTRS)

Lin, C. S.; Hasan, M. M.; Nyland, T. W.

1993-01-01

Experiments were conducted to investigate the effect of axial jet-induced mixing on the pressure reduction of a thermally stratified liquid hydrogen tank. The tank was nearly cylindrical, having a volume of about 0.144 cu m with 0.559 m in diameter and 0.711 m length. A mixer/pump unit, which had a jet nozzle outlet of 0.0221 m in diameter was located 0.178 m from the tank bottom and was installed inside the tank to generate the axial jet mixing and tank fluid circulation. Mixing tests began with the tank pressures at which the thermal stratification results in 4.9-6.2 K liquid subcooling. The mixing time and transient vapor condensation rate at the liquid-vapor interface are determined. Two mixing time correlations, based on the thermal equilibrium and pressure equilibrium, are developed and expressed as functions of system and buoyancy parameters. The limited liquid hydrogen data of the present study shows that the modified steady state condensation rate correlation may be used to predict the transient condensation rate in a mixing process if the instantaneous values of jet sub cooling and turbulence intensity at the interface are employed.

Mass transfer in thin films under counter-current gas: experiments and numerical study

NASA Astrophysics Data System (ADS)

Lucquiaud, Mathieu; Lavalle, Gianluca; Schmidt, Patrick; Ausner, Ilja; Wehrli, Marc; O Naraigh, Lennon; Valluri, Prashant

2016-11-01

Mass transfer in liquid-gas stratified flows is strongly affected by the waviness of the interface. For reactive flows, the chemical reactions occurring at the liquid-gas interface also influence the mass transfer rate. This is encountered in several technological applications, such as absorption units for carbon capture. We investigate the absorption rate of carbon dioxide in a liquid solution. The experimental set-up consists of a vertical channel where a falling film is sheared by a counter-current gas flow. We measure the absorption occurring at different flow conditions, by changing the liquid solution, the liquid flow rate and the gas composition. With the aim to support the experimental results with numerical simulations, we implement in our level-set flow solver a novel module for mass transfer taking into account a variant of the ghost-fluid formalism. We firstly validate the pure mass transfer case with and without hydrodynamics by comparing the species concentration in the bulk flow to the analytical solution. In a final stage, we analyse the absorption rate in reactive flows, and try to reproduce the experimental results by means of numerical simulations to explore the active role of the waves at the interface.

Service Learning for Engaged Work-Based Learning. Strategies for Transformative Change

ERIC Educational Resources Information Center

Hoffman, D.; Spada, K.; Fox, H. L.

2016-01-01

All 16 Wisconsin Technical College System (WTCS) colleges are committed to creating Intentional Networks Transforming Effective and Rigorous Facilitation of Assessment, Collaboration, and Education (INTERFACE). INTERFACE received a Round Three TAACCCT grant from the U.S. Department of Labor. INTERFACE is a strategic alignment between colleges,…

Novel, Integrated Reactor/Power Conversion System (LMR-AMTEC)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dmitry V. Paramonov, Lead Collaborator

2001-07-31

The overall objective of NERI Project Number 99-0198 is to assess the technical and economic feasibility, develop engineering solutions and determine a range of potential applications for ''Novel Integrated Reactor/Energy conversion Systems''. The near term goal is the design of a power supply for developing countries in remote locations in a proliferation resistant, reliable and economical way. The heart of the concept is the use of a single loop liquid metal fast reactor (LMR) with conversion of the heat directly into electricity in a Alkali Metal Thermal to Electric Converter (AMTEC). The first year of the project focused on themore » feasibility issues with a long life, high temperature liquid metal-cooled core; selection of the working fluid, core-to-AMTEC coupling scheme and interface parameters; and, energy conversion systems design and performance. Report Number STD-ES-01-0028, Revision 0, dated July 31, 2001, summarizes the work performed by Westinghouse personnel in Year One and report number UNM-ISNPS-3-2000, dated October 2000, summarizes the work performed by the Institute for Space and Nuclear Power Studies at the University of New Mexico in Year One.« less

Microfluidic electrochemical device and process for chemical imaging and electrochemical analysis at the electrode-liquid interface in-situ

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu, Xiao-Ying; Liu, Bingwen; Yang, Li

2016-03-01

A microfluidic electrochemical device and process are detailed that provide chemical imaging and electrochemical analysis under vacuum at the surface of the electrode-sample or electrode-liquid interface in-situ. The electrochemical device allows investigation of various surface layers including diffuse layers at selected depths populated with, e.g., adsorbed molecules in which chemical transformation in electrolyte solutions occurs.

2013 Chemical reactions at surfaces. Surfaces in Energy and the Environment. Gordon Research Conference and Gordon Research Seminar (April 28 - May 3, 2013 - Les Diablerets, Switzerland)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stair, Peter C.

presentations on chemistry at solid and liquid surfaces of relevance to catalysis, synthesis, photochemistry, environmental science, and tribology. Topics include: Fundamental Surface Chemistry; Catalysis; Solid Liquid and Aerosol Interfaces; Surface Photochemistry; Synthesis of Surfaces; Environmental Interfaces; Hot Topics in Surface Chemical Reactions; Tribology; Gas-Surface Scattering and Reactions; Novel Materials and Environments.

Evaporation of freely suspended single droplets: experimental, theoretical and computational simulations

NASA Astrophysics Data System (ADS)

Hołyst, R.; Litniewski, M.; Jakubczyk, D.; Kolwas, K.; Kolwas, M.; Kowalski, K.; Migacz, S.; Palesa, S.; Zientara, M.

2013-03-01

Evaporation is ubiquitous in nature. This process influences the climate, the formation of clouds, transpiration in plants, the survival of arctic organisms, the efficiency of car engines, the structure of dried materials and many other phenomena. Recent experiments discovered two novel mechanisms accompanying evaporation: temperature discontinuity at the liquid-vapour interface during evaporation and equilibration of pressures in the whole system during evaporation. None of these effects has been predicted previously by existing theories despite the fact that after 130 years of investigation the theory of evaporation was believed to be mature. These two effects call for reanalysis of existing experimental data and such is the goal of this review. In this article we analyse the experimental and the computational simulation data on the droplet evaporation of several different systems: water into its own vapour, water into the air, diethylene glycol into nitrogen and argon into its own vapour. We show that the temperature discontinuity at the liquid-vapour interface discovered by Fang and Ward (1999 Phys. Rev. E 59 417-28) is a rule rather than an exception. We show in computer simulations for a single-component system (argon) that this discontinuity is due to the constraint of momentum/pressure equilibrium during evaporation. For high vapour pressure the temperature is continuous across the liquid-vapour interface, while for small vapour pressures the temperature is discontinuous. The temperature jump at the interface is inversely proportional to the vapour density close to the interface. We have also found that all analysed data are described by the following equation: da/dt = P1/(a + P2), where a is the radius of the evaporating droplet, t is time and P1 and P2 are two parameters. P1 = -λΔT/(qeffρL), where λ is the thermal conductivity coefficient in the vapour at the interface, ΔT is the temperature difference between the liquid droplet and the vapour far from the interface, qeff is the enthalpy of evaporation per unit mass and ρL is the liquid density. The P2 parameter is the kinetic correction proportional to the evaporation coefficient. P2 = 0 only in the absence of temperature discontinuity at the interface. We discuss various models and problems in the determination of the evaporation coefficient and discuss evaporation scenarios in the case of single- and multi-component systems.

Quantum state-resolved energy transfer dynamics at gas-liquid interfaces: IR laser studies of CO2 scattering from perfluorinated liquids.

PubMed

Perkins, Bradford G; Häber, Thomas; Nesbitt, David J

2005-09-01

An apparatus for detailed study of quantum state-resolved inelastic energy transfer dynamics at the gas-liquid interface is described. The approach relies on supersonic jet-cooled molecular beams impinging on a continuously renewable liquid surface in a vacuum and exploits sub-Doppler high-resolution laser absorption methods to probe rotational, vibrational, and translational distributions in the scattered flux. First results are presented for skimmed beams of jet-cooled CO(2) (T(beam) approximately 15 K) colliding at normal incidence with a liquid perfluoropolyether (PFPE) surface at E(inc) = 10.6(8) kcal/mol. The experiment uses a tunable Pb-salt diode laser for direct absorption on the CO(2) nu(3) asymmetric stretch. Measured rotational distributions in both 00(0)0 and 01(1)0 vibrational manifolds indicate CO(2) inelastically scatters from the liquid surface into a clearly non-Boltzmann distribution, revealing nonequilibrium dynamics with average rotational energies in excess of the liquid (T(s) = 300 K). Furthermore, high-resolution analysis of the absorption profiles reveals that Doppler widths correspond to temperatures significantly warmer than T(s) and increase systematically with the J rotational state. These rotational and translational distributions are consistent with two distinct gas-liquid collision pathways: (i) a T approximately 300 K component due to trapping-desorption (TD) and (ii) a much hotter distribution (T approximately 750 K) due to "prompt" impulsive scattering (IS) from the gas-liquid interface. By way of contrast, vibrational populations in the CO(2) bending mode are inefficiently excited by scattering from the liquid, presumably reflecting much slower T-V collisional energy transfer rates.

76 FR 43743 - Pipeline Safety: Meetings of the Technical Pipeline Safety Standards Committee and the Technical...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-21

... DEPARTMENT OF TRANSPORTATION Pipeline and Hazardous Materials Safety Administration [Docket No. PHMSA-2011-0127] Pipeline Safety: Meetings of the Technical Pipeline Safety Standards Committee and the Technical Hazardous Liquid Pipeline Safety Standards Committee AGENCY: Pipeline and Hazardous Materials...

Observation of surface layering in a nonmetallic liquid

NASA Astrophysics Data System (ADS)

Mo, Haiding; Evmenenko, Guennadi; Kewalramani, Sumit; Kim, Kyungil; Dutta, Pulak; Ehrlich, Steven

2006-03-01

Non-monotonic density profiles (layers) have previously been observed at the free surfaces of many metallic liquids, but not in isotropic dielectric liquids. Whether the presence of an electron gas is necessary for surface layering has been the subject of debate. Until recently, MD simulations have suggested that layering at free liquid interface may be a generic phenomenon and is not limited to the metallic liquids^1. The theories predict that if normal liquids can be cooled down to temperatures low enough, layering structure should be observed experimentally. However, this is difficult for most molecular liquids because these liquids freeze well above the temperature necessary for observing the layering structure. By studying the surface structure of liquid TEHOS (tetrakis(2-ethylhexoxy)silane), which combines relatively low freezing point and high boiling point compared to that of most molecular liquids, we have observed the evidence of layering at the free interface of liquid TEHOS using x-ray reflectivity. When cooled to T/Tc 0.25 (well above the bulk freezing point, Tc is the critical temperature of TEHOS), the surface roughness drops sharply and density oscillations appear near the surface. Lateral ordering of the surface layers is liquid-like, just as at liquid metal surfaces. 1. E. Chac'on and P. Tarazona, Phys. Rev. Lett. 91 166103-1 (2003)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujiwara, K., E-mail: ku.fujiwara@screen.co.jp; Department of Mechanical Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871; Shibahara, M., E-mail: siba@mech.eng.osaka-u.ac.jp

A classical molecular dynamics simulation was conducted for a system composed of fluid molecules between two planar solid surfaces, and whose interactions are described by the 12-6 Lennard-Jones form. This paper presents a general description of the pressure components and interfacial tension at a fluid-solid interface obtained by the perturbative method on the basis of statistical thermodynamics, proposes a method to consider the pressure components tangential to an interface which are affected by interactions with solid atoms, and applies this method to the calculation system. The description of the perturbative method is extended to subsystems, and the local pressure componentsmore » and interfacial tension at a liquid-solid interface are obtained and examined in one- and two-dimensions. The results are compared with those obtained by two alternative methods: (a) an evaluation of the intermolecular force acting on a plane, and (b) the conventional method based on the virial expression. The accuracy of the numerical results is examined through the comparison of the results obtained by each method. The calculated local pressure components and interfacial tension of the fluid at a liquid-solid interface agreed well with the results of the two alternative methods at each local position in one dimension. In two dimensions, the results showed a characteristic profile of the tangential pressure component which depended on the direction tangential to the liquid-solid interface, which agreed with that obtained by the evaluation of the intermolecular force acting on a plane in the present study. Such good agreement suggests that the perturbative method on the basis of statistical thermodynamics used in this study is valid to obtain the local pressure components and interfacial tension at a liquid-solid interface.« less

Methods and systems for monitoring a solid-liquid interface

DOEpatents

Stoddard, Nathan G [Gettysburg, PA; Clark, Roger F [Frederick, MD

2011-10-04

Methods and systems are provided for monitoring a solid-liquid interface, including providing a vessel configured to contain an at least partially melted material; detecting radiation reflected from a surface of a liquid portion of the at least partially melted material; providing sound energy to the surface; measuring a disturbance on the surface; calculating at least one frequency associated with the disturbance; and determining a thickness of the liquid portion based on the at least one frequency, wherein the thickness is calculated based on L=(2m-1)v.sub.s/4f, where f is the frequency where the disturbance has an amplitude maximum, v.sub.s is the speed of sound in the material, and m is a positive integer (1, 2, 3, . . . ).

LIGHT NONAQUEOUS PHASE LIQUIDS

EPA Science Inventory

Nonaqueous phase liquids (NAPLS) are hydrocarbons that exist as a separate, immiscible phase when in contact with water and/or air. ifferences in the physical and chemical properties of water and NAPL result in the formation of a physical interface between the liquids which preve...

Microgravity

NASA Image and Video Library

2004-04-15

Researchers have found that as melted metals and alloys (combinations of metals) solidify, they can form with different arrangements of atoms, called microstructures. These microstructures depend on the shape of the interface (boundary) between the melted metal and the solid crystal it is forming. There are generally three shapes that the interface can take: planar, or flat; cellular, which looks like the cells of a beehive; and dendritic, which resembles tiny fir trees. Convection at this interface can affect the interface shape and hide the other phenomena (physical events). To reduce the effects of convection, researchers conduct experiments that examine and control conditions at the interface in microgravity. Microgravity also helps in the study of alloys composed of two metals that do not mix. On Earth, the liquid mixtures of these alloys settle into different layers due to gravity. In microgravity, the liquid metals do not settle, and a solid more uniform mixture of both metals can be formed.

Attoliter Control of Microliquid

NASA Astrophysics Data System (ADS)

Imura, Fumito; Kuroiwa, Hiroyuki; Nakada, Akira; Kosaka, Kouji; Kubota, Hiroshi

2007-11-01

The technology of the sub-femtoliter volume control of liquids in nanometer range pipettes (nanopipettes) has been developed for carrying out surgical operations on living cells. We focus attention on an interface forming between oil and water in a nanopipette. The interface position can be moved by increasing or decreasing the input pressure. If the volume of liquid in the nanopipette can be controlled by moving the position of the interface, cell organelles can be discharged or suctioned and a drug-solution can be injected into the cell. Quantity volume control in the pico-attoliter range using a tapered nanopipette is controlled by the condition of an interface with a convex shape toward the top of the nanopipette. The volume can be controlled by the input pressure corresponding to the interfacial radius without the use of a microscope by preliminarily preparing the pipette shape and the interface radius as a function of the input pressure.

Time-resolved determination of the potential of zero charge at polycrystalline Au/ionic liquid interfaces

NASA Astrophysics Data System (ADS)

Vargas-Barbosa, Nella M.; Roling, Bernhard

2018-05-01

The potential of zero charge (PZC) is a fundamental property that describes the electrode/electrolyte interface. The determination of the PZC at electrode/ionic liquid interfaces has been challenging due to the lack of models that fully describe these complex interfaces as well as the non-standardized approaches used to characterize them. In this work, we present a method that combines electrode immersion transient and impedance measurements for the determination of the PZC. This combined approach allows the distinction of the potential of zero free charge (pzfc), related to fast double layer charging on a millisecond timescale, from a potential of zero charge on a timescale of tens of seconds related to slower ion transport processes at the interface. Our method highlights the complementarity of these electrochemical techniques and the importance of selecting the correct timescale to execute experiments and interpret the results.

Tuning the Two-Dimensional Electron Liquid at Oxide Interfaces by Buffer-Layer-Engineered Redox Reactions.

PubMed

Chen, Yunzhong; Green, Robert J; Sutarto, Ronny; He, Feizhou; Linderoth, Søren; Sawatzky, George A; Pryds, Nini

2017-11-08

Polar discontinuities and redox reactions provide alternative paths to create two-dimensional electron liquids (2DELs) at oxide interfaces. Herein, we report high mobility 2DELs at interfaces involving SrTiO 3 (STO) achieved using polar La 7/8 Sr 1/8 MnO 3 (LSMO) buffer layers to manipulate both polarities and redox reactions from disordered overlayers grown at room temperature. Using resonant X-ray reflectometry experiments, we quantify redox reactions from oxide overlayers on STO as well as polarity induced electronic reconstruction at epitaxial LSMO/STO interfaces. The analysis reveals how these effects can be combined in a STO/LSMO/disordered film trilayer system to yield high mobility modulation doped 2DELs, where the buffer layer undergoes a partial transformation from perovskite to brownmillerite structure. This uncovered interplay between polar discontinuities and redox reactions via buffer layers provides a new approach for the design of functional oxide interfaces.

Investigation of local evaporation flux and vapor-phase pressure at an evaporative droplet interface.

PubMed

Duan, Fei; Ward, C A

2009-07-07

In the steady-state experiments of water droplet evaporation, when the throat was heating at a stainless steel conical funnel, the interfacial liquid temperature was found to increase parabolically from the center line to the rim of the funnel with the global vapor-phase pressure at around 600 Pa. The energy conservation analysis at the interface indicates that the energy required for evaporation is maintained by thermal conduction to the interface from the liquid and vapor phases, thermocapillary convection at interface, and the viscous dissipation globally and locally. The local evaporation flux increases from the center line to the periphery as a result of multiple effects of energy transport at the interface. The local vapor-phase pressure predicted from statistical rate theory (SRT) is also found to increase monotonically toward the interface edge from the center line. However, the average value of the local vapor-phase pressures is in agreement with the measured global vapor-phase pressure within the measured error bar.

Rate theory of ion pairing at the water liquid-vapor interface: A case of sodium iodide.

PubMed

Dang, Liem X; Schenter, Gregory K

2018-06-14

Studies on ion pairing at interfaces have been intensified recently because of their importance in many chemical reactive phenomena, such as ion-ion interactions that are affected by interfaces and their influence on kinetic processes. In this study, we performed simulations to examine the thermodynamics and kinetics of small polarizable sodium iodide ions in the bulk and near the water liquid-vapor interface. Using classical transition state theory, we calculated the dissociation rates and corrected them with transmission coefficients obtained from the reactive flux formalism and Grote-Hynes theory. Our results show that in addition to affecting the free energy of ions in solution, the interfacial environments significantly influence the kinetics of ion pairing. The results on the relaxation time obtained using the reactive flux formalism and Grote-Hynes theory present an unequivocal picture that the interface suppresses ion dissociation. The effects of the use of molecular models on the ion interactions as well as the ion-pair configurations at the interface are also quantified and discussed.

Rate theory of ion pairing at the water liquid-vapor interface: A case of sodium iodide

NASA Astrophysics Data System (ADS)

Dang, Liem X.; Schenter, Gregory K.

2018-06-01

Studies on ion pairing at interfaces have been intensified recently because of their importance in many chemical reactive phenomena, such as ion-ion interactions that are affected by interfaces and their influence on kinetic processes. In this study, we performed simulations to examine the thermodynamics and kinetics of small polarizable sodium iodide ions in the bulk and near the water liquid-vapor interface. Using classical transition state theory, we calculated the dissociation rates and corrected them with transmission coefficients obtained from the reactive flux formalism and Grote-Hynes theory. Our results show that in addition to affecting the free energy of ions in solution, the interfacial environments significantly influence the kinetics of ion pairing. The results on the relaxation time obtained using the reactive flux formalism and Grote-Hynes theory present an unequivocal picture that the interface suppresses ion dissociation. The effects of the use of molecular models on the ion interactions as well as the ion-pair configurations at the interface are also quantified and discussed.

Organizational Alignment Through Information Technology: A Web-Based Approach to Change

NASA Technical Reports Server (NTRS)

Heinrichs, W.; Smith, J.

1999-01-01

This paper reports on the effectiveness of web-based internet tools and databases to facilitate integration of technical organizations with interfaces that minimize modification of each technical organization.

New insights into the interface between a single-crystalline metal electrode and an extremely pure ionic liquid: slow interfacial processes and the influence of temperature on interfacial dynamics.

PubMed

Drüschler, Marcel; Borisenko, Natalia; Wallauer, Jens; Winter, Christian; Huber, Benedikt; Endres, Frank; Roling, Bernhard

2012-04-21

Ionic liquids are of high interest for the development of safe electrolytes in modern electrochemical cells, such as batteries, supercapacitors and dye-sensitised solar cells. However, electrochemical applications of ionic liquids are still hindered by the limited understanding of the interface between electrode materials and ionic liquids. In this article, we first review the state of the art in both experiment and theory. Then we illustrate some general trends by taking the interface between the extremely pure ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate and an Au(111) electrode as an example. For the study of this interface, electrochemical impedance spectroscopy was combined with in situ STM and in situ AFM techniques. In addition, we present new results for the temperature dependence of the interfacial capacitance and dynamics. Since the interfacial dynamics are characterised by different processes taking place on different time scales, the temperature dependence of the dynamics can only be reliably studied by recording and carefully analysing broadband capacitance spectra. Single-frequency experiments may lead to artefacts in the temperature dependence of the interfacial capacitance. We demonstrate that the fast capacitive process exhibits a Vogel-Fulcher-Tamman temperature dependence, since its time scale is governed by the ionic conductivity of the ionic liquid. In contrast, the slower capacitive process appears to be Arrhenius activated. This suggests that the time scale of this process is determined by a temperature-independent barrier, which may be related to structural reorganisations of the Au surface and/or to charge redistributions in the strongly bound innermost ion layer. This journal is © the Owner Societies 2012

Droplet spreading and capillary imbibition in a porous medium: A coupled IB-VOF method based numerical study

NASA Astrophysics Data System (ADS)

Das, Saurish; Patel, H. V.; Milacic, E.; Deen, N. G.; Kuipers, J. A. M.

2018-01-01

We investigate the dynamics of a liquid droplet in contact with a surface of a porous structure by means of the pore-scale level, fully resolved numerical simulations. The geometrical details of the solid porous matrix are resolved by a sharp interface immersed boundary method on a Cartesian computational grid, whereas the motion of the gas-liquid interface is tracked by a mass conservative volume of fluid method. The numerical simulations are performed considering a model porous structure that is approximated by a 3D cubical scaffold with cylindrical struts. The effect of the porosity and the equilibrium contact angle (between the gas-liquid interface and the solid struts) on the spreading behavior, liquid imbibition, and apparent contact angle (between the gas-liquid interface and the porous base) are studied. We also perform several simulations for droplet spreading on a flat surface as a reference case. Gas-liquid systems of the Laplace number, La = 45 and La = 144 × 103 are considered neglecting the effect of gravity. We report the time exponent (n) and pre-factor (C) of the power law describing the evolution of the spreading diameter (S = Ctn) for different equilibrium contact angles and porosity. Our simulations reveal that the apparent or macroscopic contact angle varies linearly with the equilibrium contact angle and increases with porosity. Not necessarily for all the wetting porous structures, a continuous capillary drainage occurs, and we find that the rate of the capillary drainage very much depends on the fluid inertia. At La = 144 × 103, numerically we capture the capillary wave induced pinch-off and daughter droplet ejection. We observe that on the porous structure the pinch-off is weak compared to that on a flat plate.

Microfluidic liquid-air dual-gradient chip for synergic effect bio-evaluation of air pollutant.

PubMed

Liu, Xian-Jun; Hu, Shan-Wen; Xu, Bi-Yi; Zhao, Ge; Li, Xiang; Xie, Fu-Wei; Xu, Jing-Juan; Chen, Hong-Yuan

2018-05-15

In this paper, a novel prototype liquid-air dual gradient chip is introduced, which has paved the way for effective synergic effect bio-evaluation of air pollutant. The chip is composed of an array of the agarose liquid-air interfaces, top air gradient layer and bottom liquid gradient layer. The novel agarose liquid-air interface allows for non-biased exposure of cells to all the substances in the air and diffusive interactions with the liquid phase; while the dual liquid-air gradient provides powerful screening abilities, which well reduced errors, saved time and cost from repeated experiment. Coupling the two functions, the chip subsequently facilitates synergic effect evaluation of both liquid and air factors on cells. Here cigarette smoke was taken as the model air pollutant, and its strong synergic effects with inflammatory level of A549 lung cancer cells on their fate were successfully quantified for the first time. These results well testified that the proposed dual-gradient chip is powerful and indispensable for bio-evaluation of air pollutant. Copyright © 2018 Elsevier B.V. All rights reserved.

Adaptive Interfaces

DTIC Science & Technology

1990-11-01

to design and implement an adaptive intelligent interface for a command-and-control-style domain. The primary functionality of the resulting...technical tasks, as follows: 1. Analysis of Current Interface Technologies 2. Dejineation of User Roles 3. Development of User Models 4. Design of Interface...Management Association (FEMA). In the initial version of the prototype, two distin-t user models were designed . One type of user modeled by the system is

A fully automated liquid–liquid extraction system utilizing interface detection

PubMed Central

Maslana, Eugene; Schmitt, Robert; Pan, Jeffrey

2000-01-01

The development of the Abbott Liquid-Liquid Extraction Station was a result of the need for an automated system to perform aqueous extraction on large sets of newly synthesized organic compounds used for drug discovery. The system utilizes a cylindrical laboratory robot to shuttle sample vials between two loading racks, two identical extraction stations, and a centrifuge. Extraction is performed by detecting the phase interface (by difference in refractive index) of the moving column of fluid drawn from the bottom of each vial containing a biphasic mixture. The integration of interface detection with fluid extraction maximizes sample throughput. Abbott-developed electronics process the detector signals. Sample mixing is performed by high-speed solvent injection. Centrifuging of the samples reduces interface emulsions. Operating software permits the user to program wash protocols with any one of six solvents per wash cycle with as many cycle repeats as necessary. Station capacity is eighty, 15 ml vials. This system has proven successful with a broad spectrum of both ethyl acetate and methylene chloride based chemistries. The development and characterization of this automated extraction system will be presented. PMID:18924693

Low-g simulation testing of propellant systems using neutral buoyancy

NASA Technical Reports Server (NTRS)

Balzer, D. L.; Lake, R. J., Jr.

1972-01-01

A two liquid, neutral buoyancy technique is being used to simulate propellant behavior in a weightless environment. By equalizing the density of two immiscible liquids within a container (propellant tank), the effect of gravity at the liquid interface is balanced. Therefore the surface-tension forces dominate to control the liquid/liquid system configuration in a fashion analogous to a liquid/gas system in a zero gravity environment.

The patient-sensor interface

PubMed Central

Crockett, G. S.

1970-01-01

During the assessment of monitoring equipment on acute medical cases in a general ward, a quantitative investigation of technical faults revealed that 44% of these occurred at the patient-sensor interface. While the attachment of the equipment was accepted by the patient and was suitable for application by nursing staff, this degree of technical breakdown indicates that more progress is necessary in the design of this aspect of monitoring equipment before it is possible to have a reliable system. ImagesFig. 1 PMID:5476136

Surface tension and long range corrections of cylindrical interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bourasseau, E.; Malfreyt, P.; Ghoufi, A., E-mail: aziz.ghoufi@univ-rennes1.fr

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,more » (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.« less

Understanding the stability of surface nanobubbles.

PubMed

Wang, Shuo; Liu, Minghuan; Dong, Yaming

2013-05-08

Surface nanobubbles emerging at solid-liquid interfaces show extreme stability. In this paper, the stability of surface nanobubbles in degassed water is discussed and investigated by AFM. The result demonstrates that surface nanobubbles are kinetically stable and the liquid/gas interface is gas impermeable. The force modulation experiment further proves that there is a layer coating on nanobubbles. These critical properties suggest that surface nanobubbles may be stabilized by a layer which has a great diffusive resistance.

Effect of accelerated crucible rotation on melt composition in high-pressure vertical Bridgman growth of cadmium zinc telluride

NASA Astrophysics Data System (ADS)

Yeckel, Andrew; Derby, Jeffrey J.

2000-02-01

Three-dimensional axisymmetric, time-dependent simulations of the high-pressure vertical Bridgman growth of large-diameter cadmium zinc telluride are performed to study the effect of accelerated crucible rotation (ACRT) on crystal growth dynamics. The model includes details of heat transfer, melt convection, solid-liquid interface shape, and dilute zinc segregation. Application of ACRT greatly improves mixing in the melt, but causes an overall increased deflection of the solid-liquid interface. The flow exhibits a Taylor-Görtler instability at the crucible sidewall, which further enhances melt mixing. The rate of mixing depends strongly on the length of the ACRT cycle, with an optimum half-cycle length between 2 and 4 Ekman time units. Significant melting of the crystal occurs during a portion of the rotation cycle, caused by periodic reversal of the secondary flow at the solid-liquid interface, indicating the possibility of compositional striations.

In Situ Probing of Ion Ordering at an Electrified Ionic Liquid/Au Interface

DOE PAGES

Sitaputra, Wattaka; Stacchiola, Dario; Wishart, James F.; ...

2017-05-12

Charge transport at the interface of electrodes and ionic liquids is critical for the use of the latter as electrolytes. In this study, a room-temperature ionic liquid, 1-ethyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonyl)imide (EMMIM TFSI), is investigated in situ under applied bias voltage with a novel method using low-energy electron and photoemission electron microscopy. Changes in photoelectron yield as a function of bias applied to electrodes provide a direct measure of the dynamics of ion reconfiguration and electrostatic responses of the EMMIM TFSI. Finally, long-range and correlated ionic reconfigurations that occur near the electrodes are found to be a function of temperature and thickness,more » which, in turn, relate to ionic mobility and different configurations for out-of-plane ordering near the electrode interfaces, with a critical transition in ion mobility for films thicker than three monolayers.« less

Surface vibrational structure at alkane liquid/vapor interfaces

NASA Astrophysics Data System (ADS)

Esenturk, Okan; Walker, Robert A.

2006-11-01

Broadband vibrational sum frequency spectroscopy (VSFS) has been used to examine the surface structure of alkane liquid/vapor interfaces. The alkanes range in length from n-nonane (C9H20) to n-heptadecane (C17H36), and all liquids except heptadecane are studied at temperatures well above their bulk (and surface) freezing temperatures. Intensities of vibrational bands in the CH stretching region acquired under different polarization conditions show systematic, chain length dependent changes. Data provide clear evidence of methyl group segregation at the liquid/vapor interface, but two different models of alkane chain structure can predict chain length dependent changes in band intensities. Each model leads to a different interpretation of the extent to which different chain segments contribute to the anisotropic interfacial region. One model postulates that changes in vibrational band intensities arise solely from a reduced surface coverage of methyl groups as alkane chain length increases. The additional methylene groups at the surface must be randomly distributed and make no net contribution to the observed VSF spectra. The second model considers a simple statistical distribution of methyl and methylene groups populating a three dimensional, interfacial lattice. This statistical picture implies that the VSF signal arises from a region extending several functional groups into the bulk liquid, and that the growing fraction of methylene groups in longer chain alkanes bears responsibility for the observed spectral changes. The data and resulting interpretations provide clear benchmarks for emerging theories of molecular structure and organization at liquid surfaces, especially for liquids lacking strong polar ordering.

Dry-Surface Simulation Method for the Determination of the Work of Adhesion of Solid-Liquid Interfaces.

PubMed

Leroy, Frédéric; Müller-Plathe, Florian

2015-08-04

We introduce a methodology, referred to as the dry-surface method, to calculate the work of adhesion of heterogeneous solid-liquid interfaces by molecular simulation. This method employs a straightforward thermodynamic integration approach to calculate the work of adhesion as the reversible work to turn off the attractive part of the actual solid-liquid interaction potential. It is formulated in such a way that it may be used either to evaluate the ability of force fields to reproduce reference values of the work of adhesion or to optimize force-field parameters with reference values of the work of adhesion as target quantities. The methodology is tested in the case of water on a generic model of nonpolar substrates with the structure of gold. It is validated through a quantitative comparison to phantom-wall calculations and against a previous characterization of the thermodynamics of the gold-water interface. It is found that the work of adhesion of water on nonpolar substrates is a nonlinear function of the microscopic solid-liquid interaction energy parameter. We also comment on the ability of mean-field approaches to predict the work of adhesion of water on nonpolar substrates. In addition, we discuss in detail the information on the solid-liquid interfacial thermodynamics delivered by the phantom-wall approach. We show that phantom-wall calculations yield the solid-liquid interfacial tension relative to the solid surface tension rather than the absolute solid-liquid interfacial tension as previously believed.

Gravitational instability of thin gas layer between two thick liquid layers

NASA Astrophysics Data System (ADS)

Pimenova, A. V.; Goldobin, D. S.

2016-12-01

We consider the problem of gravitational instability (Rayleigh-Taylor instability) of a horizontal thin gas layer between two liquid half-spaces (or thick layers), where the light liquid overlies the heavy one. This study is motivated by the phenomenon of boiling at the surface of direct contact between two immiscible liquids, where the rate of the "break-away" of the vapor layer growing at the contact interface due to development of the Rayleigh-Taylor instability on the upper liquid-gas interface is of interest. The problem is solved analytically under the assumptions of inviscid liquids and viscous weightless vapor. These assumptions correspond well to the processes in real systems, e.g., they are relevant for the case of interfacial boiling in the system water- n-heptane. In order to verify the results, the limiting cases of infinitely thin and infinitely thick gas layers were considered, for which the results can be obviously deduced from the classical problem of the Rayleigh-Taylor instability. These limiting cases are completely identical to the well-studied cases of gravity waves at the liquidliquid and liquid-gas interfaces. When the horizontal extent of the system is long enough, the wavenumber of perturbations is not limited from below, and the system is always unstable. The wavelength of the most dangerous perturbations and the rate of their exponential growth are derived as a function of the layer thickness. The dependence of the exponential growth rate on the gas layer thickness is cubic.

Interfacial tension measurement of immiscible liq uids using a capillary tube

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

Coupling compositional liquid gas Darcy and free gas flows at porous and free-flow domains interface

DOE Office of Scientific and Technical Information (OSTI.GOV)

Masson, R., E-mail: roland.masson@unice.fr; Team COFFEE INRIA Sophia Antipolis Méditerranée; Trenty, L., E-mail: laurent.trenty@andra.fr

This paper proposes an efficient splitting algorithm to solve coupled liquid gas Darcy and free gas flows at the interface between a porous medium and a free-flow domain. This model is compared to the reduced model introduced in [6] using a 1D approximation of the gas free flow. For that purpose, the gas molar fraction diffusive flux at the interface in the free-flow domain is approximated by a two point flux approximation based on a low-frequency diagonal approximation of a Steklov–Poincaré type operator. The splitting algorithm and the reduced model are applied in particular to the modelling of the massmore » exchanges at the interface between the storage and the ventilation galleries in radioactive waste deposits.« less

Crystalisation of aqueous ferrofluids at the free liquid interface investigated by specular and off-specular x-ray reflectometry

NASA Astrophysics Data System (ADS)

Gapon, I. V.; Petrenko, V. I.; Soltwedel, O.; Khaydukov, Yu N.; Kubovcikova, M.; Kopcansky, P.; Bulavin, L. A.; Avdeev, M. V.

2018-03-01

Structural organization of nanoparticles from aqueous ferrofluids on free liquid surface was studied by X-ray reflectometry. The observed layered structure at interface is associated with the evaporation of the solvent. By orienting an external magnetic during evaporation of the aqueos ferrofluids their structural organization can be manipulated. For a magnetic field applied perpendicular to the surface a more pronounced ordering along the surface normal is observed as in the case of a parallel field. Independent on the orientation of the magantic field a ∼ 20 μm thick surface layer of depleted nanoparticle concentration is found at the interface.

Curvature-induced capillary interaction of spherical particles at a liquid interface.

PubMed

Würger, Alois

2006-10-01

We consider a liquid interface with different principal curvatures +/-c and find that the mere presence of a spherical particle leads to a deformation field of quadrupolar symmetry; the corresponding "capillary quadrupole moment" is given by the ratio of the particle size and the curvature radius. The resulting pair interaction of nearby particles is anisotropic and favors the formation of aggregates of cubic symmetry. Since the single-particle trapping energy depends quadratically on curvature with a negative prefactor, a curvature gradient induces a lateral force that pushes the particles towards strongly curved regions of the interface. As an illustration we discuss the effects occurring on a catenoid.

Methods for Improving the User-Computer Interface. Technical Report.

ERIC Educational Resources Information Center

McCann, Patrick H.

This summary of methods for improving the user-computer interface is based on a review of the pertinent literature. Requirements of the personal computer user are identified and contrasted with computer designer perspectives towards the user. The user's psychological needs are described, so that the design of the user-computer interface may be…

Fabrication of metal nanoelectrodes by interfacial reactions.

PubMed

Zhu, Xinyu; Qiao, Yonghui; Zhang, Xin; Zhang, Sensen; Yin, Xiaohong; Gu, Jing; Chen, Ye; Zhu, Zhiwei; Li, Meixian; Shao, Yuanhua

2014-07-15

Despite great improvements in the past decades, the controllable fabrication of metal nanoelectrodes still remains very challenging. In this work, a simple and general way to fabricate metal nanoelectrodes (Ag, Au, and Pt) is developed. On the basis of interfacial reactions at nano-liquid/liquid interfaces supported at nanopipettes, the nanoparticles can be formed in situ and have been used to block the orifices of pipettes to make nanoelectrodes. The effect of the driving force for interfacial reaction at the liquid/liquid interface, the ratio of redox species in organic and aqueous phases, and the surface charge of the inner wall of a pipette have been studied. The fabricated nanoelectrodes have been characterized by scanning electron microscopy (SEM) and electrochemical techniques. A silver electrode with about 10 nm in radius has been employed as the scanning electrochemical microscopy (SECM) probe to explore the thickness of a water/nitrobenzene (W/NB) interface, and this value is equal to 0.8 ± 0.1 nm (n = 5). This method of fabrication of nanoelectrodes can be extended to other metal or semiconductor electrodes.

Imaging and estimating the surface heterogeneity on a droplet containing cosolvents.

PubMed

Fang, Xiaohua; Li, Bingquan; Wu, Jun; Maldarelli, Charles; Sokolov, Jonathan C; Rafailovich, Miriam H; Somasundaran, Ponisseril

2009-07-23

Cosolvents have numerous applications in many industries as well as scientific research. The shortage in the knowledge of the structures in a cosolvent system is significant. In this work, we display the spatial as well as the kinetic distribution of the cosolvents using droplets as paradigms. When an alcohol/water-containing sessile droplet evaporates on a substrate, it phase segregates into a water-enriched core and a thin alcohol prevailing shell. This is considered to be due to the different escaping rate of solvents out of the liquid-vapor (l-v) interfaces. In between the core and shell phases, there exists a rough and solid-like liquid-liquid (l-l) wall interface as marked by the fluorescent polystyrene spheres and imaged by a confocal microscope. Holes and patches of beads are observed to form on this phase boundary. The water-dispersed beads prefer to partition within the core. The shell prevails in the droplet during most of the drying and shrinks with the l-v boundary. By monitoring the morphological progression of the droplet, the composition of the cosolvent at the liquid-vapor interface is obtained.

Thermodynamic and Optical Response of Multiply Shocked Liquid Nitromethane

NASA Astrophysics Data System (ADS)

Flanders, B. M.; Winey, J. M.; Gupta, Y. M.

2015-06-01

To investigate the thermodynamic and optical response of multiply shocked liquids, particle velocity profiles were measured for liquid nitromethane (NM) subjected to stepwise loading to a peak pressure of 10 GPa. Using a multi-point velocity interferometer (VISAR), wave profiles were obtained at both the front and rear interfaces of the thin (200 μm) liquid sample to obtain data regarding the thermodynamic response and the refractive index at the intermediate stepwise loading states, in addition to the peak state. Changes in the apparent velocity at the front sample interface were well accounted for by using a Gladstone-Dale relationship to describe the NM index of refraction. The thermodynamic states of multiply shocked NM were examined by comparing the measured wave profiles to those calculated using a published NM equation of state. Although the calculated and measured particle velocity states are in good overall agreement, comparison of the calculated shock wave reverberation times at the front and rear sample interfaces with the measured values suggests that the published NM equation of state can be improved. Work supported by DOE/NNSA.

Deactivation of Cellulase at the Air-Liquid Interface Is the Main Cause of Incomplete Cellulose Conversion at Low Enzyme Loadings.

PubMed

Bhagia, Samarthya; Dhir, Rachna; Kumar, Rajeev; Wyman, Charles E

2018-01-22

Amphiphilic additives such as bovine serum albumin (BSA) and Tween have been used to improve cellulose hydrolysis by cellulases. However, there has been a lack of clarity to explain their mechanism of action in enzymatic hydrolysis of pure or low-lignin cellulosic substrates. In this work, a commercial Trichoderma reesei enzyme preparation and the amphiphilic additives BSA and Tween 20 were applied for hydrolysis of pure Avicel cellulose. The results showed that these additives only had large effects on cellulose conversion at low enzyme to substrate ratios when the reaction flasks were shaken. Furthermore, changes in the air-liquid interfacial area profoundly affected cellulose conversion, but surfactants reduced or prevented cellulase deactivation at the air-liquid interface. Not shaking the flasks or adding low amounts of surfactant resulted in near theoretical cellulose conversion at low enzyme loadings given enough reaction time. At low enzyme loadings, hydrolysis of cellulose in lignocellulosic biomass with low lignin content suffered from enhanced enzyme deactivation at the air-liquid interface.

Microscopic aspects of wetting using classical density functional theory

NASA Astrophysics Data System (ADS)

Yatsyshin, P.; Durán-Olivencia, M.-A.; Kalliadasis, S.

2018-07-01

Wetting is a rather efficient mechanism for nucleation of a phase (typically liquid) on the interface between two other phases (typically solid and gas). In many experimentally accessible cases of wetting, the interplay between the substrate structure, and the fluid–fluid and fluid–substrate intermolecular interactions brings about an entire ‘zoo’ of possible fluid configurations, such as liquid films with a thickness of a few nanometers, liquid nanodrops and liquid bridges. These fluid configurations are often associated with phase transitions occurring at the solid–gas interface and at lengths of just several molecular diameters away from the substrate. In this special issue article, we demonstrate how a fully microscopic classical density-functional framework can be applied to the efficient, rational and systematic exploration of the rich phase space of wetting phenomena. We consider a number of model prototype systems such as wetting on a planar wall, a chemically patterned wall and a wedge. Through density-functional computations we demonstrate that for these simply structured substrates the behaviour of the solid–gas interface is already highly complex and non-trivial.

Free-surface flow of liquid oxygen under non-uniform magnetic field

NASA Astrophysics Data System (ADS)

Bao, Shi-Ran; Zhang, Rui-Ping; Wang, Kai; Zhi, Xiao-Qin; Qiu, Li-Min

2017-01-01

The paramagnetic property of oxygen makes it possible to control the two-phase flow at cryogenic temperatures by non-uniform magnetic fields. The free-surface flow of vapor-liquid oxygen in a rectangular channel was numerically studied using the two-dimensional phase field method. The effects of magnetic flux density and inlet velocity on the interface deformation, flow pattern and pressure drop were systematically revealed. The liquid level near the high-magnetic channel center was lifted upward by the inhomogeneous magnetic field. The interface height difference increased almost linearly with the magnetic force. For all inlet velocities, pressure drop under 0.25 T was reduced by 7-9% due to the expanded local cross-sectional area, compared to that without magnetic field. This work demonstrates the effectiveness of employing non-uniform magnetic field to control the free-surface flow of liquid oxygen. This non-contact method may be used for promoting the interface renewal, reducing the flow resistance, and improving the flow uniformity in the cryogenic distillation column, which may provide a potential for enhancing the operating efficiency of cryogenic air separation.

On the origin of the driving force in the Marangoni propelled gas bubble trapping mechanism.

PubMed

Miniewicz, A; Quintard, C; Orlikowska, H; Bartkiewicz, S

2017-07-19

Gas bubbles can be trapped and then manipulated with laser light. In this report, we propose the detailed optical trapping mechanism of gas bubbles confined inside a thin light-absorbing liquid layer between two glass plates. The necessary condition of bubble trapping in this case is the direct absorption of light by the solution containing a dye. Due to heat release, fluid whirls propelled by the surface Marangoni effect at the liquid/gas interface emerge and extend to large distances. We report the experimental microscopic observation of the origin of whirls at an initially flat liquid/air interface as well as at the curved interface of a liquid/gas bubble and support this finding with advanced numerical simulations using the finite element method within the COMSOL Multiphysics platform. The simulation results were in good agreement with the observations, which allowed us to propose a simple physical model for this particular trapping mechanism, to establish the origin of forces attracting bubbles toward a laser beam and to predict other phenomena related to this effect.

Physicochemical properties of the AC-excited helium discharges using a water electrode

NASA Astrophysics Data System (ADS)

Hafiz, Imran Ahmad QAZI; Yiying, XIN; Muhammad Ajmal, KHAN; Heping, LI; Lu, ZHOU; Chengyu, BAO

2018-07-01

In this paper, the AC-excited helium discharges generated between the powered needle electrode enclosed in a conical quartz tube and the grounded de-ionized water electrode are investigated. The current and voltage waveforms exhibit a transition from the glow-like to streamer-like mode discharges, which forms a stable cone-shaped structure at the gas–liquid interface. In this region, the air and water vapor diffusion initiate various physical–chemical processes leading to substantial changes of the primary species emission intensities (e.g., OH, N2, NO, and O) and the rotational temperatures. The experimentally measured rotational temperature at the gas–liquid interface is 870 K from the N2(C–B) band with a power input of 26 W. With the prolongation of the discharge time, significant changes in the discharge voltage and current, discharge emission patterns, instantaneous concentrations of the secondary species (e.g., H2O2, {{{NO}}}2-, and {{{NO}}}3-) in the liquid phase, pH values and electrical conductivities of the liquids are observed experimentally. The present study is helpful for deepening the understandings to the basic physical–chemical processes in the discharges in contact with liquids, especially to those occurring in the vicinity of the gas–liquid interface, and also for promoting existing and potential applications of such type of discharges in the fields of environmental protection, biomedicine, agriculture, and so on.

Incorporating contact angles in the surface tension force with the ACES interface curvature scheme

NASA Astrophysics Data System (ADS)

Owkes, Mark

2017-11-01

In simulations of gas-liquid flows interacting with solid boundaries, the contact line dynamics effect the interface motion and flow field through the surface tension force. The surface tension force is directly proportional to the interface curvature and the problem of accurately imposing a contact angle must be incorporated into the interface curvature calculation. Many commonly used algorithms to compute interface curvatures (e.g., height function method) require extrapolating the interface, with defined contact angle, into the solid to allow for the calculation of a curvature near a wall. Extrapolating can be an ill-posed problem, especially in three-dimensions or when multiple contact lines are near each other. We have developed an accurate methodology to compute interface curvatures that allows for contact angles to be easily incorporated while avoiding extrapolation and the associated challenges. The method, known as Adjustable Curvature Evaluation Scale (ACES), leverages a least squares fit of a polynomial to points computed on the volume-of-fluid (VOF) representation of the gas-liquid interface. The method is tested by simulating canonical test cases and then applied to simulate the injection and motion of water droplets in a channel (relevant to PEM fuel cells).

Calculation of a solid/liquid surface tension: A methodological study

NASA Astrophysics Data System (ADS)

Dreher, T.; Lemarchand, C.; Soulard, L.; Bourasseau, E.; Malfreyt, P.; Pineau, N.

2018-01-01

The surface tension of a model solid/liquid interface constituted of a graphene sheet surrounded by liquid methane has been computed using molecular dynamics in the Kirkwood-Buff formalism. We show that contrary to the fluid/fluid case, the solid/liquid case can lead to different structurations of the first fluid layer, leading to significantly different values of surface tension. Therefore we present a statistical approach that consists in running a series of molecular simulations of similar systems with different initial conditions, leading to a distribution of surface tensions from which an average value and uncertainty can be extracted. Our results suggest that these distributions converge as the system size increases. Besides we show that surface tension is not particularly sensitive to the choice of the potential energy cutoff and that long-range corrections can be neglected contrary to what we observed in the liquid/vapour interfaces. We have not observed the previously reported commensurability effect.

Liquid lens based on electrowetting: a new adaptive component for imaging applications in consumer electronics

NASA Astrophysics Data System (ADS)

Crassous, Jerome; Gabay, Claude; Liogier, Gaetan; Berge, Bruno

2004-12-01

A new technology for focus variation with direct electric control without moving part will be presented. The technology relies on an interface between two non-miscible transparent liquids, which can be deformed by electrowetting. This technology has been developed since 10 years in the lab and starts to be available commercially, with the following characteristics: large amplitude of dioptric correction (20 dioptries for a 5mm pupil size), fast response, small power consumption and good transmission in the visible range, clear pupil 1-10mm diameter. This paper will show the basic principle, as well as the physical limitations and optical aberrations due to differential thermal expansion of the two liquids in the cell. Experimental measurements made with a Schack Hartmann wave front analyzer will be presented, as well as numerical simulations of the liquid-liquid interface. Applications will be discussed, mainly in consumer electronics.

Graphene Microcapsule Arrays for Combinatorial Electron Microscopy and Spectroscopy in Liquids

DOE PAGES

Yulaev, Alexander; Guo, Hongxuan; Strelcov, Evgheni; ...

2017-04-27

Atomic-scale thickness, molecular impermeability, low atomic number, and mechanical strength make graphene an ideal electron-transparent membrane for material characterization in liquids and gases with scanning electron microscopy and spectroscopy. Here in this paper, we present a novel sample platform made of an array of thousands of identical isolated graphene-capped microchannels with high aspect ratio. A combination of a global wide field of view with high resolution local imaging of the array allows for high throughput in situ studies as well as for combinatorial screening of solutions, liquid interfaces, and immersed samples. We demonstrate the capabilities of this platform by studyingmore » a pure water sample in comparison with alkali halide solutions, a model electrochemical plating process, and beam-induced crystal growth in liquid electrolyte. Spectroscopic characterization of liquid interfaces and immersed objects with Auger and X-ray fluorescence analysis through the graphene membrane are also demonstrated.« less

Matching time and spatial scales of rapid solidification: dynamic TEM experiments coupled to CALPHAD-informed phase-field simulations

NASA Astrophysics Data System (ADS)

Perron, Aurelien; Roehling, John D.; Turchi, Patrice E. A.; Fattebert, Jean-Luc; McKeown, Joseph T.

2018-01-01

A combination of dynamic transmission electron microscopy (DTEM) experiments and CALPHAD-informed phase-field simulations was used to study rapid solidification in Cu-Ni thin-film alloys. Experiments—conducted in the DTEM—consisted of in situ laser melting and determination of the solidification kinetics by monitoring the solid-liquid interface and the overall microstructure evolution (time-resolved measurements) during the solidification process. Modelling of the Cu-Ni alloy microstructure evolution was based on a phase-field model that included realistic Gibbs energies and diffusion coefficients from the CALPHAD framework (thermodynamic and mobility databases). DTEM and post mortem experiments highlighted the formation of microsegregation-free columnar grains with interface velocities varying from ˜0.1 to ˜0.6 m s-1. After an ‘incubation’ time, the velocity of the planar solid-liquid interface accelerated until solidification was complete. In addition, a decrease of the temperature gradient induced a decrease in the interface velocity. The modelling strategy permitted the simulation (in 1D and 2D) of the solidification process from the initially diffusion-controlled to the nearly partitionless regimes. Finally, results of DTEM experiments and phase-field simulations (grain morphology, solute distribution, and solid-liquid interface velocity) were consistent at similar time (μs) and spatial scales (μm).

Matching time and spatial scales of rapid solidification: Dynamic TEM experiments coupled to CALPHAD-informed phase-field simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perron, Aurelien; Roehling, John D.; Turchi, Patrice E. A.

A combination of dynamic transmission electron microscopy (DTEM) experiments and CALPHAD-informed phase-field simulations was used to study rapid solidification in Cu–Ni thin-film alloys. Experiments—conducted in the DTEM—consisted of in situ laser melting and determination of the solidification kinetics by monitoring the solid–liquid interface and the overall microstructure evolution (time-resolved measurements) during the solidification process. Modelling of the Cu–Ni alloy microstructure evolution was based on a phase-field model that included realistic Gibbs energies and diffusion coefficients from the CALPHAD framework (thermodynamic and mobility databases). DTEM and post mortem experiments highlighted the formation of microsegregation-free columnar grains with interface velocities varying frommore » ~0.1 to ~0.6 m s –1. After an 'incubation' time, the velocity of the planar solid–liquid interface accelerated until solidification was complete. In addition, a decrease of the temperature gradient induced a decrease in the interface velocity. The modelling strategy permitted the simulation (in 1D and 2D) of the solidification process from the initially diffusion-controlled to the nearly partitionless regimes. Lastly, results of DTEM experiments and phase-field simulations (grain morphology, solute distribution, and solid–liquid interface velocity) were consistent at similar time (μs) and spatial scales (μm).« less

Theory of tailorable optical response of two-dimensional arrays of plasmonic nanoparticles at dielectric interfaces.

PubMed

Sikdar, Debabrata; Kornyshev, Alexei A

2016-09-22

Two-dimensional arrays of plasmonic nanoparticles at interfaces are promising candidates for novel optical metamaterials. Such systems materialise from 'top-down' patterning or 'bottom-up' self-assembly of nanoparticles at liquid/liquid or liquid/solid interfaces. Here, we present a comprehensive analysis of an extended effective quasi-static four-layer-stack model for the description of plasmon-resonance-enhanced optical responses of such systems. We investigate in detail the effects of the size of nanoparticles, average interparticle separation, dielectric constants of the media constituting the interface, and the nanoparticle position relative to the interface. Interesting interplays of these different factors are explored first for normally incident light. For off-normal incidence, the strong effects of the polarisation of light are found at large incident angles, which allows to dynamically tune the reflectance spectra. All the predictions of the theory are tested against full-wave simulations, proving this simplistic model to be adequate within the quasi-static limit. The model takes seconds to calculate the system's optical response and makes it easy to unravel the effect of each system parameter. This helps rapid rationalization of experimental data and understanding of the optical signals from these novel 'metamaterials', optimised for light reflection or harvesting.

Theory of tailorable optical response of two-dimensional arrays of plasmonic nanoparticles at dielectric interfaces

PubMed Central

Sikdar, Debabrata; Kornyshev, Alexei A.

2016-01-01

Two-dimensional arrays of plasmonic nanoparticles at interfaces are promising candidates for novel optical metamaterials. Such systems materialise from ‘top–down’ patterning or ‘bottom–up’ self-assembly of nanoparticles at liquid/liquid or liquid/solid interfaces. Here, we present a comprehensive analysis of an extended effective quasi-static four-layer-stack model for the description of plasmon-resonance-enhanced optical responses of such systems. We investigate in detail the effects of the size of nanoparticles, average interparticle separation, dielectric constants of the media constituting the interface, and the nanoparticle position relative to the interface. Interesting interplays of these different factors are explored first for normally incident light. For off-normal incidence, the strong effects of the polarisation of light are found at large incident angles, which allows to dynamically tune the reflectance spectra. All the predictions of the theory are tested against full-wave simulations, proving this simplistic model to be adequate within the quasi-static limit. The model takes seconds to calculate the system’s optical response and makes it easy to unravel the effect of each system parameter. This helps rapid rationalization of experimental data and understanding of the optical signals from these novel ‘metamaterials’, optimised for light reflection or harvesting. PMID:27652788

Surfactant effects on heat transfer at gas/liquid interfaces

NASA Astrophysics Data System (ADS)

Lopez, J. M.; Hirsa, A. H.

2000-01-01

A formulation of a canonical model to elucidate the interplay and competition between three primary sources of heat and mass transfer in non-isothermal systems with gas/liquid interfaces is presented. The nonlinear interaction between (i) buoyancy driven flow in the bulk, (ii) thermal Marangoni flow at the gas/liquid interface, and (iii) surfactant Marangoni flow at the interface is considered. A numerical model of the Navier-Stokes and energy equations is being developed for a simple, axisymmetric flow geometry. The boundary conditions for the Navier-Stokes equations are functions of the intrinsic viscoelastic properties of the interface, specifically the surface tension and the surface viscosities. A flow geometry which is amenable to both experiments and computations for elucidating the separate effects of the three mechanisms consists of an annular region bounded by a stationary inner and an outer cylinder and floor, and a free surface. The flow is driven by the temperature difference between the inner and outer cylinder which are set independently, and the floor is insulated. The predictions of the model for earth-g can be compared to laboratory measurements of the velocity field, and the surface temperature distribution. The predictions of the model for arbitrary gravity may be subsequently tested in the microgravity environment. .

Matching time and spatial scales of rapid solidification: Dynamic TEM experiments coupled to CALPHAD-informed phase-field simulations

DOE PAGES

Perron, Aurelien; Roehling, John D.; Turchi, Patrice E. A.; ...

2017-12-05

A combination of dynamic transmission electron microscopy (DTEM) experiments and CALPHAD-informed phase-field simulations was used to study rapid solidification in Cu–Ni thin-film alloys. Experiments—conducted in the DTEM—consisted of in situ laser melting and determination of the solidification kinetics by monitoring the solid–liquid interface and the overall microstructure evolution (time-resolved measurements) during the solidification process. Modelling of the Cu–Ni alloy microstructure evolution was based on a phase-field model that included realistic Gibbs energies and diffusion coefficients from the CALPHAD framework (thermodynamic and mobility databases). DTEM and post mortem experiments highlighted the formation of microsegregation-free columnar grains with interface velocities varying frommore » ~0.1 to ~0.6 m s –1. After an 'incubation' time, the velocity of the planar solid–liquid interface accelerated until solidification was complete. In addition, a decrease of the temperature gradient induced a decrease in the interface velocity. The modelling strategy permitted the simulation (in 1D and 2D) of the solidification process from the initially diffusion-controlled to the nearly partitionless regimes. Lastly, results of DTEM experiments and phase-field simulations (grain morphology, solute distribution, and solid–liquid interface velocity) were consistent at similar time (μs) and spatial scales (μm).« less

Critical behavior of phase interfaces in porous media: Analysis of scaling properties with the use of noncoherent and coherent light

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zimnyakov, D. A., E-mail: zimnykov@sgu.ru; Sadovoi, A. V.; Vilenskii, M. A.

2009-02-15

Image sequences of the surface of disordered layers of porous medium (paper) obtained under noncoherent and coherent illumination during capillary rise of a liquid are analyzed. As a result, principles that govern the critical behavior of the interface between liquid and gaseous phases during its pinning are established. By a cumulant analysis of speckle-modulated images of the surface and by the statistical analysis of binarized difference images of the surface under noncoherent illumination, it is shown that the macroscopic dynamics of the interface at the stage of pinning is mainly controlled by the power law dependence of the appearance ratemore » of local instabilities (avalanches) of the interface on the critical parameter, whereas the growth dynamics of the local instabilities is controlled by the diffusion of a liquid in a layer and weakly depends on the critical parameter. A phenomenological model is proposed for the macroscopic dynamics of the phase interface for interpreting experimental data. The values of critical indices are determined that characterize the samples under test within this model. These values are compared with the results of numerical simulation for discrete models of directed percolation corresponding to the Kardar-Parisi-Zhang equation.« less

Dynamic stabilization of the Rayleigh-Taylor instability of miscible liquids and the related "frozen waves"

NASA Astrophysics Data System (ADS)

Wolf, Gerd Gerhard H.

2018-02-01

Superimposed miscible liquids, the heavier one on top, when subjected to vibrations vertical to their interface (dynamic stabilization), can only be maintained for a certain period. A mechanism is presented explaining the resulting process of degradation and "anomalous diffusion" through that interface. Superimposed liquids, the lighter one on top, exposed to horizontal vibrations, develop a saw-tooth-like pattern called "frozen waves." These are subject to conditions similar to those of dynamic stabilization and, if miscible, thus can also only be maintained for a certain period. A further analysis of these processes would be desirable, also in view of their relation to analogue phenomena.

Discovery LOX

NASA Image and Video Library

2003-11-11

In the Orbiter Processing Facility, workers prepare to install the liquid oxygen feedline for the 17-inch disconnect on orbiter Discovery. The 17-inch liquid oxygen and liquid hydrogen disconnects provide the propellant feed interface from the external tank to the orbiter main propulsion system and the three Shuttle main engines.

Micro-cones on a liquid interface in high electric field: Ionization effects

NASA Astrophysics Data System (ADS)

Subbotin, Andrey V.; Semenov, Alexander N.

2018-02-01

We formulate and explore electrohydrodynamic equations for conductive liquids taking dissociation/recombination processes into account and discover a novel type of liquid cones which carry both surface and net bulk charge and can be formed on a liquid interface in an electric field. The bulk charge is generated by the corona discharge due to a high electric field at the cone apex. We establish correlation between the cone angle and physical parameters of the liquid on the one hand and the electric current passing through the cone on the other hand. It is shown that the current strongly increases when the cone angle tends to a critical value which is a function of the dielectric permittivity of the liquid. The cone stability with respect to axially symmetric perturbations is analyzed. It is shown that the cones with apex angles close to the critical angle are likely to be stable. The effect of the imposed flow on the cone apex stability is also discussed.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yao, Kaisheng; Henan Normal University, School of Chemistry and Environmental Science, Key Laboratory of Green Chemical Media and Reactions, Xin xiang, Henan 453007; Lu, Weiwei

A novel method was proposed for successful fabrication of CuS nanostructures with various morphologies. At the ionic liquids (ILs)-modulated CHCl{sub 3}-H{sub 2}O interface, copper cupferronate [Cu(cup){sub 2}] in CHCl{sub 3} reacted with thiourea in water to generate CuS nanostructures via a solvothermal reaction process. The effects of alkyl chain length of imidazolium cations and nature of anions of the ILs, molar ratio of Cu(cup){sub 2} to thiourea, the reaction temperature and time on the morphology of the products were studied systematically. It was shown that by changing alkyl chain length of imidazolium cations and nature of anions of the ILs,more » CuS nanostructures with various morphologies, including flowers, urchins, large nanodisks and nanoparticles, could be obtained at the liquid-liquid interface, and the ILs played important template roles in directing the formation of CuS nanostructures. Furthermore, the as-prepared CuS samples exhibited high catalytic activity for photodegradation of methyl orange and thermal decomposition of ammonium perchlorate. - Graphical abstract: At the ionic liquids-modulated CHCl{sub 3}-H{sub 2}O interface, the CuS nanostructures with the various morphologies of flowers, urchins, large nanodisks and nanoparticles have been successfully prepared via a solvothermal reaction process. Highlights: Black-Right-Pointing-Pointer The properties of oil-H{sub 2}O interface can be modulated by employing different ILs. Black-Right-Pointing-Pointer The modulated interface has been used to prepare CuS nanostructures with various morphologies. Black-Right-Pointing-Pointer The CuS samples exhibited high catalytic activity for the photodegradation of methyl orange.« less

Smoothed particle hydrodynamics method for evaporating multiphase flows.

PubMed

Yang, Xiufeng; Kong, Song-Charng

2017-09-01

The smoothed particle hydrodynamics (SPH) method has been increasingly used for simulating fluid flows; however, its ability to simulate evaporating flow requires significant improvements. This paper proposes an SPH method for evaporating multiphase flows. The present SPH method can simulate the heat and mass transfers across the liquid-gas interfaces. The conservation equations of mass, momentum, and energy were reformulated based on SPH, then were used to govern the fluid flow and heat transfer in both the liquid and gas phases. The continuity equation of the vapor species was employed to simulate the vapor mass fraction in the gas phase. The vapor mass fraction at the interface was predicted by the Clausius-Clapeyron correlation. An evaporation rate was derived to predict the mass transfer from the liquid phase to the gas phase at the interface. Because of the mass transfer across the liquid-gas interface, the mass of an SPH particle was allowed to change. Alternative particle splitting and merging techniques were developed to avoid large mass difference between SPH particles of the same phase. The proposed method was tested by simulating three problems, including the Stefan problem, evaporation of a static drop, and evaporation of a drop impacting a hot surface. For the Stefan problem, the SPH results of the evaporation rate at the interface agreed well with the analytical solution. For drop evaporation, the SPH result was compared with the result predicted by a level-set method from the literature. In the case of drop impact on a hot surface, the evolution of the shape of the drop, temperature, and vapor mass fraction were predicted.

Air-liquid interface exposure to aerosols of poorly soluble nanomaterials induces different biological activation levels compared to exposure to suspensions.

PubMed

Loret, Thomas; Peyret, Emmanuel; Dubreuil, Marielle; Aguerre-Chariol, Olivier; Bressot, Christophe; le Bihan, Olivier; Amodeo, Tanguy; Trouiller, Bénédicte; Braun, Anne; Egles, Christophe; Lacroix, Ghislaine

2016-11-03

Recently, much progress has been made to develop more physiologic in vitro models of the respiratory system and improve in vitro simulation of particle exposure through inhalation. Nevertheless, the field of nanotoxicology still suffers from a lack of relevant in vitro models and exposure methods to predict accurately the effects observed in vivo, especially after respiratory exposure. In this context, the aim of our study was to evaluate if exposing pulmonary cells at the air-liquid interface to aerosols of inhalable and poorly soluble nanomaterials generates different toxicity patterns and/or biological activation levels compared to classic submerged exposures to suspensions. Three nano-TiO 2 and one nano-CeO 2 were used. An exposure system was set up using VitroCell® devices to expose pulmonary cells at the air-liquid interface to aerosols. A549 alveolar cells in monocultures or in co-cultures with THP-1 macrophages were exposed to aerosols in inserts or to suspensions in inserts and in plates. Submerged exposures in inserts were performed, using similar culture conditions and exposure kinetics to the air-liquid interface, to provide accurate comparisons between the methods. Exposure in plates using classical culture and exposure conditions was performed to provide comparable results with classical submerged exposure studies. The biological activity of the cells (inflammation, cell viability, oxidative stress) was assessed at 24 h and comparisons of the nanomaterial toxicities between exposure methods were performed. Deposited doses of nanomaterials achieved using our aerosol exposure system were sufficient to observe adverse effects. Co-cultures were more sensitive than monocultures and biological responses were usually observed at lower doses at the air-liquid interface than in submerged conditions. Nevertheless, the general ranking of the nanomaterials according to their toxicity was similar across the different exposure methods used. We showed that exposure of cells at the air-liquid interface represents a valid and sensitive method to assess the toxicity of several poorly soluble nanomaterials. We underlined the importance of the cellular model used and offer the possibility to deal with low deposition doses by using more sensitive and physiologic cellular models. This brings perspectives towards the use of relevant in vitro methods of exposure to assess nanomaterial toxicity.

Thermal force induced by the presence of a particle near a solidifying interface.

PubMed

Hadji, L

2001-11-01

The presence of a foreign particle in the melt, ahead of a solid-liquid interface, leads to the onset of interfacial deformations if the thermal conductivity of the particle, k(p), differs from that of the melt, k(l). In this paper, the influence of the thermal conductivity contrast on the interaction between the solidifying interface and the particle is quantified. We show that the interface distortion gives rise to a thermal force whose expression is given by F(th)=2piLGa3(1-alpha)/(2+alpha)T(m), where L is the latent heat of fusion per unit volume, T(m) is the melting point, a is the particle's radius, G the thermal gradient in the liquid phase and alpha=k(p)/k(l). The derivation makes use of the following assumptions: (i) the particle is small compared to the horizontal extent of the interface, (ii) the particle is placed in the near proximity of the deformable solid-liquid interface, and (iii) the interface is practically immobile in the calculation of the thermal field, i.e., V

Numerical study of hydrophobic micron particle's impaction on liquid surface

NASA Astrophysics Data System (ADS)

Ji, Bingqiang; Song, Qiang; Yao, Qiang

2017-07-01

In this study, a simulation method is established for the impaction of micron particles on liquid surfaces, by which the processes of two impaction modes (submergence and oscillation) are studied. The submergence is found to go through three stages, each of which shows different characteristics of particle velocity and gas-liquid interface variance. The dominant forces of the early and late times of the submergence mode are hydrodynamic force and surface tension, respectively, the accumulated work of which is in the same order. The lost particle kinetic energy is converted to the surface energy of the interfaces, the internal energy and the kinetic energy of fluids. The primary part of the oscillation is the first cycle, and the characteristics of its sinking process are similar to that of the submergence. In the reverting stage, the particle rising velocity increases first and then decreases, and the cavity retracts until the gas-liquid interface flattens. The dominant forces of the early and late times of the reverting stage are surface tension and hydrodynamic force, respectively. The positive accumulated work of surface tension on the particle is considerably limited due to the large contact angle hysteresis at the early times of the reverting stage. The negative accumulated work of the hydrodynamic force on the particle at the late times causes a fast decrease in particle kinetic energy, which leads to particle floating on the gas-liquid interface. The results are helpful in understanding the mechanism of micron particle impaction and developing the prediction method of attachment efficiency.

IR and SFG vibrational spectroscopy of the water bend in the bulk liquid and at the liquid-vapor interface, respectively.

PubMed

Ni, Yicun; Skinner, J L

2015-07-07

Vibrational spectroscopy of the water bending mode has been investigated experimentally to study the structure of water in condensed phases. In the present work, we calculate the theoretical infrared (IR) and sum-frequency generation (SFG) spectra of the HOH bend in liquid water and at the water liquid/vapor interface using a mixed quantum/classical approach. Classical molecular dynamics simulation is performed by using a recently developed water model that explicitly includes three-body interactions and yields a better description of the water surface. Ab-initio-based transition frequency, dipole, polarizability, and intermolecular coupling maps are developed for the spectral calculations. The calculated IR and SFG spectra show good agreement with the experimental measurements. In the theoretical imaginary part of the SFG susceptibility for the water liquid/vapor interface, we find two features: a negative band centered at 1615 cm(-1) and a positive band centered at 1670 cm(-1). We analyze this spectrum in terms of the contributions from molecules in different hydrogen-bond classes to the SFG spectral density and also compare to SFG results for the OH stretch. SFG of the water bending mode provides a complementary picture of the heterogeneous hydrogen-bond configurations at the water surface.

IR and SFG vibrational spectroscopy of the water bend in the bulk liquid and at the liquid-vapor interface, respectively

NASA Astrophysics Data System (ADS)

Ni, Yicun; Skinner, J. L.

2015-07-01

Vibrational spectroscopy of the water bending mode has been investigated experimentally to study the structure of water in condensed phases. In the present work, we calculate the theoretical infrared (IR) and sum-frequency generation (SFG) spectra of the HOH bend in liquid water and at the water liquid/vapor interface using a mixed quantum/classical approach. Classical molecular dynamics simulation is performed by using a recently developed water model that explicitly includes three-body interactions and yields a better description of the water surface. Ab-initio-based transition frequency, dipole, polarizability, and intermolecular coupling maps are developed for the spectral calculations. The calculated IR and SFG spectra show good agreement with the experimental measurements. In the theoretical imaginary part of the SFG susceptibility for the water liquid/vapor interface, we find two features: a negative band centered at 1615 cm-1 and a positive band centered at 1670 cm-1. We analyze this spectrum in terms of the contributions from molecules in different hydrogen-bond classes to the SFG spectral density and also compare to SFG results for the OH stretch. SFG of the water bending mode provides a complementary picture of the heterogeneous hydrogen-bond configurations at the water surface.

Experimental study of the flow pattern around a bubble confined in a microfluidic Hele-Shaw cell

NASA Astrophysics Data System (ADS)

Tsoumpas, Yannis; Fajolles, Christophe; Malloggi, Florent

2017-11-01

The flow field around a bubble moving with respect to a surrounding liquid in a Hele-Shaw cell can usually be characterized by a recirculating flow, which is typically attributed to a Marangoni effect due to surface tension gradients generated by a non-uniform distribution of surfactants (or temperature) along the liquid-gas interface. In the present study, we try to visualize such a flow employing 3D micro-particle tracking velocimetry. We perform experiments on an immobile flattened air bubble that is surrounded by a flow of aqueous solution of surfactant (SDS), in a microfluidic chamber described in the work of Sungyon Lee et al.. The suspending fluid is seeded with spherical micro-particles, with those captured by the recirculating flow orbiting in a three-dimensional trajectory in the vicinity of the liquid-air interface. We address the effect of velocity of the surrounding fluid, surfactant concentration and bubble radius on the recirculating flow pattern. The case of a liquid-liquid interface, with a hexadecane drop as the dispersed phase, is also discussed. The authors would like to acknowledge the financial support of Enhanced Eurotalents program (an FP7 Marie Skłodowska-Curie COFUND program) & ANR (ANR-13-BS09-0011).

IR and SFG vibrational spectroscopy of the water bend in the bulk liquid and at the liquid-vapor interface, respectively

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ni, Yicun; Skinner, J. L.

Vibrational spectroscopy of the water bending mode has been investigated experimentally to study the structure of water in condensed phases. In the present work, we calculate the theoretical infrared (IR) and sum-frequency generation (SFG) spectra of the HOH bend in liquid water and at the water liquid/vapor interface using a mixed quantum/classical approach. Classical molecular dynamics simulation is performed by using a recently developed water model that explicitly includes three-body interactions and yields a better description of the water surface. Ab-initio-based transition frequency, dipole, polarizability, and intermolecular coupling maps are developed for the spectral calculations. The calculated IR and SFGmore » spectra show good agreement with the experimental measurements. In the theoretical imaginary part of the SFG susceptibility for the water liquid/vapor interface, we find two features: a negative band centered at 1615 cm{sup −1} and a positive band centered at 1670 cm{sup −1}. We analyze this spectrum in terms of the contributions from molecules in different hydrogen-bond classes to the SFG spectral density and also compare to SFG results for the OH stretch. SFG of the water bending mode provides a complementary picture of the heterogeneous hydrogen-bond configurations at the water surface.« less

Foam fractionation as a tool to study the air-water interface structure-function relationship of wheat gluten hydrolysates.

PubMed

Wouters, Arno G B; Rombouts, Ine; Schoebrechts, Nele; Fierens, Ellen; Brijs, Kristof; Blecker, Christophe; Delcour, Jan A

2017-03-01

Enzymatic hydrolysis of wheat gluten protein improves its solubility and produces hydrolysates with foaming properties which may find applications in food products. First, we here investigated whether foam-liquid fractionation can concentrate wheat gluten peptides with foaming properties. Foam and liquid fractions had high and very low foam stability (FS), respectively. In addition, foam fractions were able to decrease surface tension more pronouncedly than un-fractionated samples and liquid fractions, suggesting they are able to arrange themselves more efficiently at an interface. As a second objective, foam fractionation served as a tool to study the structural properties of the peptides, causing these differences in air-water interfacial behavior. Zeta potential and surface hydrophobicity measurements did not fully explain these differences but suggested that hydrophobic interactions at the air-water interface are more important than electrostatic interactions. RP-HPLC showed a large overlap between foam and liquid fractions. However, a small fraction of very hydrophobic peptides with relatively high average molecular mass was clearly enriched in the foam fraction. These peptides were also more concentrated in un-fractionated DH 2 hydrolysates, which had high FS, than in DH 6 hydrolysates, which had low FS. These peptides most likely play a key role in stabilizing the air-water interface. Copyright © 2016 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harris, J.M.

Chemical phenomena occurring at boundaries between insulating solids and liquids (adsorption, partition, monolayer self-assembly, catalysis, and chemical reactions) are important to energy-related analytical chemistry. These phenomena are central to chromatography, solid-phase extraction, immobilized analytical reagents, and optical sensors. Chemical interactions in these processes cannot generally be identified solely by equilibrium surface concentrations, since the steady-state behavior does not reveal the mechanism or rates of surface reactions. Goal therefore is to develop surface-sensitive spectroscopies by which chemical kinetics at liquid/solid interfaces can be observed on time-scales from nanoseconds to seconds. In the first year, we have used Joule-discharge heating kinetics tomore » study pore structure of silica gels; effects of pore diameter, particle size, and chemical modification on pore connectivity were investigated. Temperature-jump relaxation measurements of sorption/desorption kinetics at liquid/solid interfaces were also carried out using Joule heating; kinetic barriers to sorption of ions from solution were found for both C18 and Cl surfaces. Through a collaboration with Fritz-Haber Institute in Berlin, we were able to acquire laser temperature-jump data on kinetics at liquid/solid interfaces using a colloidal sample. We also quantified the rate of migration of covalently attached ligands on silica surfaces; from the temperature dependence, the large energy barrier to migration was estimated. A review of applications of electronic spectroscopy (absorption and fluorescence) to reversed-phase chromatographic interfaces was published.« less

Interfacial nonequilibrium and Bénard-Marangoni instability of a liquid-vapor system

NASA Astrophysics Data System (ADS)

Margerit, J.; Colinet, P.; Lebon, G.; Iorio, C. S.; Legros, J. C.

2003-10-01

We study Bénard-Marangoni instability in a system formed by a horizontal liquid layer and its overlying vapor. The liquid is lying on a hot rigid plate and the vapor is bounded by a cold parallel plate. A pump maintains a reduced pressure in the vapor layer and evacuates the vapor. This investigation is undertaken within the classical quasisteady approximation for both the vapor and the liquid phases. The two layers are separated by a deformable interface. Temporarily frozen temperature and velocity distributions are employed at each instant for the stability analysis, limited to infinitesimal disturbances (linear regime). We use irreversible thermodynamics to model the phase change under interfacial nonequilibrium. Within this description, the interface appears as a barrier for transport of both heat and mass. Hence, in contrast with previous studies, we consider the possibility of a temperature jump across the interface, as recently measured experimentally. The stability analysis shows that the interfacial resistances to heat and mass transfer have a destabilizing influence compared to an interface that is in thermodynamic equilibrium. The role of the fluctuations in the vapor phase on the onset of instability is discussed. The conditions to reduce the system to a one phase model are also established. Finally, the influence of the evaporation parameters and of the presence of an inert gas on the marginal stability curves is discussed.

Wetting phenomenon in the liquid-vapor phase coexistence of a partially miscible Lennard-Jones binary mixture

NASA Astrophysics Data System (ADS)

Ramírez-Santiago, Guillermo; Díaz-Herrera, Enrique; Moreno Razo, José A.

2004-03-01

We have carried out extensive equilibrium MD simulations to study wetting phenomena in the liquid-vapor phase coexistence of a partially miscible binary LJ mixture. We find that in the temperature range 0.60 ≤ T^* < 0.80, the system separates forming a liquid A-liquid B interface in coexistence with the vapor phase. At higher temperatures, 0.80 ≤ T^* < 1.25 the liquid phases are wet by the vapor phase. By studying the behavior of the surface tension as a function of temperature we estimate the wetting transition temperature (WTT) to be T^*_w≃ 0.80. The adsorption of molecules at the liquid-liquid interface shows a discontinuity at about T^*≃ 0.79 suggesting that the wetting transition is a first order phase transition. These results are in agreement with some experiments carried out in fluid binary mixtures. In addition, we estimated the consolute temperature to be T^* _cons≃ 1.25. The calculated phase diagram of the mixture suggest the existence of a tricritical point.

Human influences on forest ecosystems: the southern wildland-urban interface assessment: summary report

Treesearch

Edward A. Macie; L. Annie Hermansen

2003-01-01

This summary report synthesizes the findings contained in the Southern Wildland-Urban Interface Assessment (General Technical Report SRS-55). The Assessment provides a review of critical wildland-urban interface issues, challenges, and needs for the Southern United States. Topics include population and demographic trends, economic and tax issues, land use planning and...

Interface Configuration Experiments (ICE) Explore the Effects of Microgravity on Fluids

NASA Technical Reports Server (NTRS)

1996-01-01

The Interface Configuration Experiment (ICE) is actually a series of experiments that explore the striking behavior of liquid-vapor interfaces (i.e., fluid surfaces) in a low gravity environment under which major shifts in liquid position can arise from small changes in container shape or contact angle. Although these experiments are designed to test current mathematical theory, there are numerous practical applications that could result from these studies. When designing fluid management systems for space-based operations, it is important to be able to predict the locations and configurations that fluids will assume in containers under low-gravity conditions. The increased ability to predict, and hence control, fluid interfaces is vital to systems and/or processes where capillary forces play a significant role both in space and on the Earth. Some of these applications are in general coating processes (paints, pesticides, printing, etc.), fluid transport in porous media (ground water flows, oil recovery, etc.), liquid propellant systems in space (liquid fuel and oxygen), capillary-pumped loops and heat pipes, and space-based life-support systems. In space, almost every fluid system is affected, if not dominated, by capillarity. Knowledge of the liquid-vapor interface behavior, and in particular the interface shape from which any analysis must begin, is required as a foundation to predict how these fluids will react in microgravity and on Earth. With such knowledge, system designs can be optimized, thereby decreasing costs and complexity, while increasing performance and reliability. ICE has increased, and will continue to increase this knowledge, as it probes the specific peculiarities of current theory upon which our current understanding of these effects is based. Several versions of ICE were conducted in NASA Lewis Research Center's drop towers and on the space shuttle during the first and second United States Microgravity Laboratory missions (USML-1 and USML-2). Additional tests are planned for the space shuttle and for the Russian Mir space station. These studies will focus on interfacial problems concerning surface existence, uniqueness, configuration, stability, and flow characteristics.

Surface thermodynamics of planar, cylindrical, and spherical vapour-liquid interfaces of water

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lau, Gabriel V.; Müller, Erich A.; Jackson, George

2015-03-21

The test-area (TA) perturbation approach has been gaining popularity as a methodology for the direct computation of the interfacial tension in molecular simulation. Though originally implemented for planar interfaces, the TA approach has also been used to analyze the interfacial properties of curved liquid interfaces. Here, we provide an interpretation of the TA method taking the view that it corresponds to the change in free energy under a transformation of the spatial metric for an affine distortion. By expressing the change in configurational energy of a molecular configuration as a Taylor expansion in the distortion parameter, compact relations are derivedmore » for the interfacial tension and its energetic and entropic components for three different geometries: planar, cylindrical, and spherical fluid interfaces. While the tensions of the planar and cylindrical geometries are characterized by first-order changes in the energy, that of the spherical interface depends on second-order contributions. We show that a greater statistical uncertainty is to be expected when calculating the thermodynamic properties of a spherical interface than for the planar and cylindrical cases, and the evaluation of the separate entropic and energetic contributions poses a greater computational challenge than the tension itself. The methodology is employed to determine the vapour-liquid interfacial tension of TIP4P/2005 water at 293 K by molecular dynamics simulation for planar, cylindrical, and spherical geometries. A weak peak in the curvature dependence of the tension is observed in the case of cylindrical threads of condensed liquid at a radius of about 8 Å, below which the tension is found to decrease again. In the case of spherical drops, a marked decrease in the tension from the planar limit is found for radii below ∼ 15 Å; there is no indication of a maximum in the tension with increasing curvature. The vapour-liquid interfacial tension tends towards the planar limit for large system sizes for both the cylindrical and spherical cases. Estimates of the entropic and energetic contributions are also evaluated for the planar and cylindrical geometries and their magnitudes are in line with the expectations of our simple analysis.« less

Towards Molecular Characterization of Mineral-Organic Matter Interface Using In Situ Liquid Secondary Ion Mass Spectrometry

NASA Astrophysics Data System (ADS)

Zhu, Z.; Yu, X. Y.

2017-12-01

Organo-Mineral-Microbe interactions in terrestrial ecosystems are of great interest. Quite a few models have been developed through extensive efforts in this field. However, predictions from current models are far from being accurate, and many debates still exist. One of the major reasons is that most experimental data generated from bulk analysis, and the information of molecular dynamics occurring at mineral-organic matter interface is rare. Such information has been difficult to obtain, due to lack of suitable in situ analysis tools. Recently, we have developed in situ liquid secondary ion mass spectrometry (SIMS) at Pacific Northwest National Laboratory1, and it has shown promise to provide both elemental and molecular information at vacuum-liquid and solid-liquid interfaces.2 In this presentation, we demonstrate that in situ liquid SIMS can provide critical molecular information at solid substrate-live biofilm interface.3 Shewanella oneidensis is used as a model micro-organism and silicon nitride as a model mineral surface. Of particular interest, biologically relevant water clusters have been first observed in the living biofilms. Characteristic fragments of biofilm matrix components such as proteins, polysaccharides, and lipids can be molecularly examined. Furthermore, characteristic fatty acids (e.g., palmitic acid), quinolone signal, and riboflavin fragments were found to respond after the biofilm is treated with Cr(VI), leading to biofilm dispersal. Significant changes in water clusters and quorum sensing signals indicative of intercellular communication in the aqueous environment were observed, suggesting that they might result in fatty acid synthesis and inhibition of riboflavin production. The Cr(VI) reduction seems to follow the Mtr pathway leading to Cr(III) formation. Our approach potentially opens a new avenue for in-situ understanding of mineral-organo or mineral-microbe interfaces using in situ liquid SIMS and super resolution fluorescence microscopy. References:1 Hua, X. et al. Analyst 139, 1609-1613, (2014).2 Zhou, Y. F. et al. J Am Soc Mass Spectr 27, 2006-2013, (2016).3 Ding, Y. Z. et al. Anal Chem 88, 11244-11252, (2016).

CMMI (Trademark) for Acquisition, Version 1.2

DTIC Science & Technology

2007-11-01

conjunction with the development of the operational concept to derive more detailed and prec inclu even t . The level of detail of contractual...technical solution, different products or product components ma suppliers. idate Requirem Requirements Ana t the intended operational environment will have...Technical Solutions SP 1.1 Select Technical So SP 1.2 Analyze Selected T SP 1.3 Conduct Technical SG 2 Perform Interface Managemen SP 2.1 Select

Ion distributions in electrolyte confined by multiple dielectric interfaces

NASA Astrophysics Data System (ADS)

Jing, Yufei; Zwanikken, Jos W.; Jadhao, Vikram; de La Cruz, Monica

2014-03-01

The distribution of ions at dielectric interfaces between liquids characterized by different dielectric permittivities is crucial to nanoscale assembly processes in many biological and synthetic materials such as cell membranes, colloids and oil-water emulsions. The knowledge of ionic structure of these systems is also exploited in energy storage devices such as double-layer super-capacitors. The presence of multiple dielectric interfaces often complicates computing the desired ionic distributions via simulations or theory. Here, we use coarse-grained models to compute the ionic distributions in a system of electrolyte confined by two planar dielectric interfaces using Car-Parrinello molecular dynamics simulations and liquid state theory. We compute the density profiles for various electrolyte concentrations, stoichiometric ratios and dielectric contrasts. The explanations for the trends in these profiles and discuss their effects on the behavior of the confined charged fluid are also presented.

Optical patient interface in femtosecond laser-assisted cataract surgery: contact corneal applanation versus liquid immersion.

PubMed

Talamo, Jonathan H; Gooding, Philip; Angeley, David; Culbertson, William W; Schuele, Georg; Andersen, Daniel; Marcellino, George; Essock-Burns, Emma; Batlle, Juan; Feliz, Rafael; Friedman, Neil J; Palanker, Daniel

2013-04-01

To compare 2 optical patient interface designs used for femtosecond laser-assisted cataract surgery. Optimedica Corp., Santa Clara, California, USA, and Centro Laser, Santo Domingo, Dominican Republic. Experimental and clinical studies. Laser capsulotomy was performed during cataract surgery with a curved contact lens interface (CCL) or a liquid optical immersion interface (LOI). The presence of corneal folds, incomplete capsulotomy, subconjunctival hemorrhage, and eye movement during laser treatment were analyzed using video and optical coherence tomography. The induced rise of intraocular pressure (IOP) was measured in porcine and cadaver eyes. Corneal folds were identified in 70% of the CCL cohort; 63% of these had areas of incomplete capsulotomies beneath the corneal folds. No corneal folds or incomplete capsulotomies were identified in the LOI cohort. The mean eye movement during capsulotomy creation (1.5 sec) was 50 μm with a CCL and 20 μm with an LOI. The LOI cohort had 36% less subconjunctival hemorrhage than the CCL cohort. During suction, the mean IOP rise was 32.4 mm Hg ± 3.4 (SD) in the CCL group and 17.7 ± 2.1 mm Hg in the LOI group. Curved contact interfaces create corneal folds that can lead to incomplete capsulotomy during laser cataract surgery. A liquid interface eliminated corneal folds, improved globe stability, reduced subconjunctival hemorrhage, and lowered IOP rise. Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Model study on transesterification of soybean oil to biodiesel with methanol using solid base catalyst.

PubMed

Liu, Xuejun; Piao, Xianglan; Wang, Yujun; Zhu, Shenlin

2010-03-25

Modeling of the transesterification of vegetable oils to biodiesel using a solid base as a catalyst is very important because the mutual solubilities of oil and methanol will increase with the increasing biodiesel yield. The heterogeneous liquid-liquid-solid reaction system would become a liquid-solid system when the biodiesel reaches a certain content. In this work, we adopted a two-film theory and a steady state approximation assumption, then established a heterogeneous liquid-liquid-solid model in the first stage. After the diffusion coefficients on the liquid-liquid interface and the liquid-solid interface were calculated on the basis of the properties of the system, the theoretical value of biodiesel productivity changing with time was obtained. The predicted values were very near the experimental data, which indicated that the proposed models were suitable for the transesterification of soybean oil to biodiesel when solid bases were used as catalysts. Meanwhile, the model indicated that the transesterification reaction was controlled by both mass transfer and reaction. The total resistance will decrease with the increase in biodiesel yield in the liquid-liquid-solid stage. The solid base catalyst exhibited an activation energy range of 9-20 kcal/mol, which was consistent with the reported activation energy range of homogeneous catalysts.

Functions and requirements document for interim store solidified high-level and transuranic waste

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith-Fewell, M.A., Westinghouse Hanford

1996-05-17

The functions, requirements, interfaces, and architectures contained within the Functions and Requirements (F{ampersand}R) Document are based on the information currently contained within the TWRS Functions and Requirements database. The database also documents the set of technically defensible functions and requirements associated with the solidified waste interim storage mission.The F{ampersand}R Document provides a snapshot in time of the technical baseline for the project. The F{ampersand}R document is the product of functional analysis, requirements allocation and architectural structure definition. The technical baseline described in this document is traceable to the TWRS function 4.2.4.1, Interim Store Solidified Waste, and its related requirements, architecture,more » and interfaces.« less

Mathematical model to analyze the dissolution behavior of metastable crystals or amorphous drug accompanied with a solid-liquid interface reaction.

PubMed

Hirai, Daiki; Iwao, Yasunori; Kimura, Shin-Ichiro; Noguchi, Shuji; Itai, Shigeru

2017-04-30

Metastable crystals and the amorphous state of poorly water-soluble drugs in solid dispersions (SDs), are subject to a solid-liquid interface reaction upon exposure to a solvent. The dissolution behavior during the solid-liquid interface reaction often shows that the concentration of drugs is supersaturated, with a high initial drug concentration compared with the solubility of stable crystals but finally approaching the latter solubility with time. However, a method for measuring the precipitation rate of stable crystals and/or the potential solubility of metastable crystals or amorphous drugs has not been established. In this study, a novel mathematical model that can represent the dissolution behavior of the solid-liquid interface reaction for metastable crystals or amorphous drug was developed and its validity was evaluated. The theory for this model was based on the Noyes-Whitney equation and assumes that the precipitation of stable crystals at the solid-liquid interface occurs through a first-order reaction. Moreover, two models were developed, one assuming that the surface area of the drug remains constant because of the presence of excess drug in the bulk and the other that the surface area changes in time-dependency because of agglomeration of the drug. SDs of Ibuprofen (IB)/polyvinylpyrrolidone (PVP) were prepared and their dissolution behaviors under non-sink conditions were fitted by the models to evaluate improvements in solubility. The model assuming time-dependent surface area showed good agreement with experimental values. Furthermore, by applying the model to the dissolution profile, parameters such as the precipitation rate and the potential solubility of the amorphous drug were successfully calculated. In addition, it was shown that the improvement in solubility with supersaturation was able to be evaluated quantitatively using this model. Therefore, this mathematical model would be a useful tool to quantitatively determine the supersaturation concentration of a metastable drug from solid dispersions. Copyright © 2017 Elsevier B.V. All rights reserved.

Estimation of the curvature of the solid liquid interface during Bridgman crystal growth

NASA Astrophysics Data System (ADS)

Barat, Catherine; Duffar, Thierry; Garandet, Jean-Paul

1998-11-01

An approximate solution for the solid/liquid interface curvature due to the crucible effect in crystal growth is derived from simple heat flux considerations. The numerical modelling of the problem carried out with the help of the finite element code FIDAP supports the predictions of our analytical expression and allows to identify its range of validity. Experimental interface curvatures, measured in gallium antimonide samples grown by the vertical Bridgman method, are seen to compare satisfactorily to analytical and numerical results. Other literature data are also in fair agreement with the predictions of our models in the case where the amount of heat carried by the crucible is small compared to the overall heat flux.

A Simple Inexpensive Bridgman-Stockbarger Crystal Growth System for Organic Materials

NASA Technical Reports Server (NTRS)

Choi, J.; Aggarwal, M. D.; Wang, W. S.; Metzl, R.; Bhat, K.; Penn, Benjamin G.; Frazier, Donald O.

1996-01-01

Direct observation of solid-liquid interface is important for the directional solidification to determine the desired interface shape by controlling the growth parameters. To grow good quality single crystals of novel organic nonlinear optical materials, a simple inexpensive Bridgman-Stockbarger (BS) crystal growth system has been designed and fabricated. Two immiscible liquids have been utilized to create two zones for this crystal growth system. Bulk single crystals of benzil derivative and n-salicylidene-aniline have been successfully grown in this system. The optimum lowering rate has been found to be 0.1 mm/h for the flat interface. Results on the crystal growth and other parameters of the grown crystals are presented.

Numerical study of drop spreading on a flat surface

NASA Astrophysics Data System (ADS)

Wang, Sheng; Desjardins, Olivier

2017-11-01

In this talk, we perform a numerical study of a droplet on a flat surface with special emphasis on capturing the spreading dynamics. The computational methodology employed is tailored for simulating large-scale two-phase flows within complex geometries. It combines a conservative level-set method to capture the liquid-gas interface, a conservative immersed boundary method to represent the solid-fluid interface, and a sub-grid curvature model at the triple-point to implicitly impose the contact angle of the liquid-gas interface. The performance of the approach is assessed in the inertial droplet spreading regime, the viscous spreading regime of high viscosity drops, and with the capillary oscillation of low viscosity droplets.

Near-field deformation of a liquid interface by atomic force microscopy.

PubMed

Mortagne, C; Chireux, V; Ledesma-Alonso, R; Ogier, M; Risso, F; Ondarçuhu, T; Legendre, D; Tordjeman, Ph

2017-07-01

We experiment the interaction between a liquid puddle and a spherical probe by Atomic Force Microscopy (AFM) for a probe radius R ranging from 10 nm to 30 μm. We have developed a new experimental setup by coupling an AFM with a high-speed camera and an inverted optical microscope. Interaction force-distance curves (in contact mode) and frequency shift-distance curves (in frequency modulation mode) are measured for different bulk model liquids for which the probe-liquid Hamaker constant H_{pl} is known. The experimental results, analyzed in the frame of the theoretical model developed in Phys. Rev. Lett. 108, 106104 (2012)PRLTAO0031-900710.1103/PhysRevLett.108.106104 and Phys. Rev. E 85, 061602 (2012)PLEEE81539-375510.1103/PhysRevE.85.061602, allow to determine the "jump-to-contact" critical distance d_{min} below which the liquid jumps and wets the probe. Comparison between theory and experiments shows that the probe-liquid interaction at nanoscale is controlled by the liquid interface deformation. This work shows a very good agreement between the theoretical model and the experiments and paves the way to experimental studies of liquids at the nanoscale.

Deformation and breakup of liquid-liquid threads, jets, and drops

NASA Astrophysics Data System (ADS)

Doshi, Pankaj

The formation and breakup of two-fluid jets and drops find application in various industrially important processes like microencapsulation, inkjet printing, dispersion and emulsion formation, micro fluidics. Two important aspects of these problems are studied in this thesis. The first regards the study of the dynamics of a two-fluid jet issuing out of a concentric nozzle and breaking into multiple liquid drops. The second aspect concerns the study of the dynamics of liquid-liquid interface rupture. Highly robust and accurate numerical algorithms based on the Galerkin finite element method (G/FEM) and elliptic mesh generation technique are developed. The most important results of this research are the prediction of compound drop formation and volume partitioning between primary drop and satellite drops, which are of critical importance for microencapsulation technology. Another equally important result is computational and experimental demonstration of a self-similar behavior for the rupture of liquid-liquid interface. The final focus is the study of the pinch-off dynamics of generalized-Newtonian fluids with deformation-rate-dependent rheology using asymptotic analysis and numerical computation. A significant result is the first ever prediction of self-similar pinch-off of liquid threads of generalized Newtonian fluids.

Near-field deformation of a liquid interface by atomic force microscopy

NASA Astrophysics Data System (ADS)

Mortagne, C.; Chireux, V.; Ledesma-Alonso, R.; Ogier, M.; Risso, F.; Ondarçuhu, T.; Legendre, D.; Tordjeman, Ph.

2017-07-01

We experiment the interaction between a liquid puddle and a spherical probe by Atomic Force Microscopy (AFM) for a probe radius R ranging from 10 nm to 30 μ m . We have developed a new experimental setup by coupling an AFM with a high-speed camera and an inverted optical microscope. Interaction force-distance curves (in contact mode) and frequency shift-distance curves (in frequency modulation mode) are measured for different bulk model liquids for which the probe-liquid Hamaker constant Hp l is known. The experimental results, analyzed in the frame of the theoretical model developed in Phys. Rev. Lett. 108, 106104 (2012), 10.1103/PhysRevLett.108.106104 and Phys. Rev. E 85, 061602 (2012), 10.1103/PhysRevE.85.061602, allow to determine the "jump-to-contact" critical distance dmin below which the liquid jumps and wets the probe. Comparison between theory and experiments shows that the probe-liquid interaction at nanoscale is controlled by the liquid interface deformation. This work shows a very good agreement between the theoretical model and the experiments and paves the way to experimental studies of liquids at the nanoscale.

The DoD Gateway Information System: Bibliography, Directory of Resources, Prototype Experience, [and] User Interface Design.

ERIC Educational Resources Information Center

Cotter, Gladys A.; And Others

The Defense Technical Information Center (DTIC), an organization charged with providing information services to the Department of Defense (DoD) scientific and technical community, actively seeks ways to promote access to and utilization of scientific and technical information (STI) databases, online services, and networks relevant to the conduct…

40 CFR 61.61 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... has a probe that moves through the gas/liquid interface in a storage or transfer vessel and indicates... which may consist of any fluids, either as a liquid and/or gas) discharged directly or ultimately to the.... (l) In vinyl chloride service means that a piece of equipment either contains or contacts a liquid...

40 CFR 61.61 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... has a probe that moves through the gas/liquid interface in a storage or transfer vessel and indicates... which may consist of any fluids, either as a liquid and/or gas) discharged directly or ultimately to the.... (l) In vinyl chloride service means that a piece of equipment either contains or contacts a liquid...

40 CFR 61.61 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... has a probe that moves through the gas/liquid interface in a storage or transfer vessel and indicates... which may consist of any fluids, either as a liquid and/or gas) discharged directly or ultimately to the.... (l) In vinyl chloride service means that a piece of equipment either contains or contacts a liquid...

Interface colloidal robotic manipulator

DOEpatents

Aronson, Igor; Snezhko, Oleksiy

2015-08-04

A magnetic colloidal system confined at the interface between two immiscible liquids and energized by an alternating magnetic field dynamically self-assembles into localized asters and arrays of asters. The colloidal system exhibits locomotion and shape change. By controlling a small external magnetic field applied parallel to the interface, structures can capture, transport, and position target particles.

Amphiphile-Induced Reorganization of Nematic Liquid Crystals at Aqueous Interfaces

NASA Astrophysics Data System (ADS)

Rahimi, Amin; Ramezani-Dakhel, Hadi; Pendery, Joel; Abbott, Nicholas; de Pablo, Juan; Juan de Pablo Team, Prof; Nicholas Abbott Collaboration, Prof

Recent studies have shown that ordering transitions in 4-cyano-4'-pentylbiphenyl (5CB) molecules can be triggered by the self-assembly of specific amphiphiles near a flat aqueous-LC interface. In the absence of adsorbed amphiphiles, LC molecules adopt a parallel orientation at the aqueous interface. Self-assembly of amphiphile molecules at the LC-aqueous interface triggers a spontaneous reorientation of the LC at the aqueous interface. A number of observations indicate that the hydrophilic headgroup of the surfactant has marginal effect on the orientation of 5CB whereas the aliphatic tail structure, length, and conformation greatly affect the ordering of the LC. The structural reorganization of liquid crystals at aqueous interfaces has been primarily ascribed to a weakening of the surface anchoring strength induced by amphiphile molecules. Such explanations, however, have only been supported by a posteriorimicroscopic observations. The underlying mechanism of such an ordering transition and the effect of amphiphile structure remain poorly understood. Here, we study the nature of molecular interactions between amphiphiles, 5CB, and water to understand the mechanism of ordering transitions using atomistic molecular dynamics simulations.

Vibrational sum-frequency generation spectroscopy of ionic liquid 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate at the air-water interface

NASA Astrophysics Data System (ADS)

Saha, Ankur; SenGupta, Sumana; Kumar, Awadhesh; Choudhury, Sipra; Naik, Prakash D.

2016-08-01

The structure and orientation of room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate [PF3(C2F5)3], commonly known as [bmim][fap], have been investigated at the air-[bmim][fap] and air-water interfaces, employing vibrational sum-frequency generation (VSFG) spectroscopy. The VSFG spectra in the CH stretch region suggest presence of the [bmim] cation at the interfaces. Studies reveal that the butyl chain protrudes out into air, and the imidazolium ring lies almost planar to the interface. The CH stretch intensities get enhanced at the air-water interface, mainly because of polar orientation of imidazolium cation induced by interfacial water molecules. The OH stretch intensities are also enhanced at the air-water interface due to polar orientation of interfacial water molecules induced by [bmim][fap]. The Brewster angle microscopy suggests self aggregation of [bmim][fap] in the presence of water, and the aggregation becomes extensive showing dense surface domains with time. However, the surface pressure is almost unaffected due to aggregation.

Pseudo-transient heat transfer in vertical Bridgman crystal growth of semi-transparent materials

NASA Astrophysics Data System (ADS)

Barvinschi, F.; Nicoara, I.; Santailler, J. L.; Duffar, T.

1998-11-01

The temperature distribution and the solid-liquid interface shape during semi-transparent crystal growth have been studied by modelling a vertical Bridgman technique, using a pseudo-transient approximation in an ideal configuration. The heat transfer equation and the boundary conditions have been solved by the finite-element method. It has been pointed out that the optical absorption coefficients of the liquid and solid phases have a major effect on the thermal field, especially on the shape and location of the crystallization interface.

SURFACE INACTIVATION OF BACTERIAL VIRUSES AND OF PROTEINS

PubMed Central

Adams, Mark H.

1948-01-01

1. The seven bacterial viruses of the T group active against E. coli, are rapidly inactivated at gas-liquid interfaces. 2. The kinetics of this inactivation whether brought about by shaking or by bubbling with nitrogen are those of a first order reaction. 3. This inactivation may be prevented by the addition of enough protein to maintain the gas-liquid interface in a saturated condition. 4. The analogy between this phenomenon and the surface denaturation of proteins is pointed out and discussed. PMID:18917025

Gas-liquid interface-mediated room-temperature synthesis of "clean" PdNiP alloy nanoparticle networks with high catalytic activity for ethanol oxidation.

PubMed

Wang, Rongfang; Ma, Yuanyuan; Wang, Hui; Key, Julian; Ji, Shan

2014-11-04

PdNiP alloy nanoparticle networks (PdNiP NN) were prepared by simultaneous reduction of PdCl2, NiCl2 and NaH2PO2 with NaBH4via a gas-liquid interface reaction at room temperature using N2 bubbles. PdNiP NN had markedly higher activity and durability for ethanol oxidation than PdNi nanoparticle networks and PdNiP grain aggregates.

Experimental and Theoretical Probing of Molecular Dynamics at Catalytic and Ionic Liquid Interfaces

DTIC Science & Technology

2014-04-01

15. SUBJECT TERMS Surface, interface,  photocatalysis , fluorescence yield, ionic liquid, reactive force field    16. SECURITY CLASSIFICATION OF: 17...2, 3 which are promising photocatalysts for hydrogen production via photocatalytic water splitting. 1. Experimental The new experimental setup...Wang, G. Liu, G. Q. Lu, H.-M. Cheng, Int. J. of Hydrogen Energ., 2010, 35, 8199- 8205. 3. F. Xu, Y. Yuan, H. Han, D. Wu, Z. Gao, K. Jiang, CrystEngComm

Adsorption and solvation of ethanol at the water liquid-vapor interface: a molecular dynamics study

NASA Technical Reports Server (NTRS)

Wilson, M. A.; Pohorille, A.

1997-01-01

The free energy profiles of methanol and ethanol at the water liquid-vapor interface at 310K were calculated using molecular dynamics computer simulations. Both alcohols exhibit a pronounced free energy minimum at the interface and, therefore, have positive adsorption at this interface. The surface excess was computed from the Gibbs adsorption isotherm and was found to be in good agreement with experimental results. Neither compound exhibits a free energy barrier between the bulk and the surface adsorbed state. Scattering calculations of ethanol molecules from a gas phase thermal distribution indicate that the mass accommodation coefficient is 0.98, and the molecules become thermalized within 10 ps of striking the interface. It was determined that the formation of the solvation structure around the ethanol molecule at the interface is not the rate-determining step in its uptake into water droplets. The motion of an ethanol molecule in a water lamella was followed for 30 ns. The time evolution of the probability distribution of finding an ethanol molecule that was initially located at the interface is very well described by the diffusion equation on the free energy surface.

Multivalent-Ion-Activated Protein Adsorption Reflecting Bulk Reentrant Behavior.

PubMed

Fries, Madeleine R; Stopper, Daniel; Braun, Michal K; Hinderhofer, Alexander; Zhang, Fajun; Jacobs, Robert M J; Skoda, Maximilian W A; Hansen-Goos, Hendrik; Roth, Roland; Schreiber, Frank

2017-12-01

Protein adsorption at the solid-liquid interface is an important phenomenon that often can be observed as a first step in biological processes. Despite its inherent importance, still relatively little is known about the underlying microscopic mechanisms. Here, using multivalent ions, we demonstrate the control of the interactions and the corresponding adsorption of net-negatively charged proteins (bovine serum albumin) at a solid-liquid interface. This is demonstrated by ellipsometry and corroborated by neutron reflectivity and quartz-crystal microbalance experiments. We show that the reentrant condensation observed within the rich bulk phase behavior of the system featuring a nonmonotonic dependence of the second virial coefficient on salt concentration c_{s} is reflected in an intriguing way in the protein adsorption d(c_{s}) at the interface. Our findings are successfully described and understood by a model of ion-activated patchy interactions within the framework of the classical density functional theory. In addition to the general challenge of connecting bulk and interface behavior, our work has implications for, inter alia, nucleation at interfaces.

Metastable nanobubbles at the solid-liquid interface due to contact angle hysteresis.

PubMed

Nishiyama, Takashi; Yamada, Yutaka; Ikuta, Tatsuya; Takahashi, Koji; Takata, Yasuyuki

2015-01-27

Nanobubbles exist at solid-liquid interfaces between pure water and hydrophobic surfaces with very high stability, lasting in certain cases up to several days. Not only semispherical but also other shapes, such as micropancakes, are known to exist at such interfaces. However, doubt has been raised as to whether or not the nanobubbles are gas-phase entities. In this study, surface nanobubbles at a pure water-highly ordered pyrolytic graphite (HOPG) interface were investigated by peak force quantitative nanomechanics (PF-QNM). Multiple isolated nanobubbles generated by the solvent-exchange method were present on the terraced areas, avoiding the steps of the HOPG surface. Adjacent nanobubbles coalesced and formed metastable nanobubbles. Coalescence was enhanced by the PF-QNM measurement. We determined that nanobubbles can exist for a long time because of nanoscale contact angle hysteresis at the water-HOPG interface. Moreover, the hydrophilic steps of HOPG were avoided during coalescence, providing evidence that the nanobubbles are truly gas phase.