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Sample records for wettability capillary action

  1. FUNDAMENTALS OF RESERVOIR SURFACE ENERGY AS RELATED TO SURFACE PROPERTIES, WETTABILITY, CAPILLARY ACTION, AND OIL RECOVERY FROM FRACTURED RESERVOIRS BY SPONTANEOUS IMBIBITION

    SciTech Connect

    Norman R. Morrow

    2004-07-01

    The objective of this project is to increase oil recovery from fractured reservoirs through improved fundamental understanding of the process of spontaneous imbibition by which oil is displaced from the rock matrix into the fractures. Spontaneous imbibition is fundamentally dependent on the reservoir surface free energy but this has never been investigated for rocks. In this project, the surface free energy of rocks will be determined by using liquids that can be solidified within the rock pore space at selected saturations. Thin sections of the rock then provide a two-dimensional view of the rock minerals and the occupant phases. Saturations and oil/rock, water/rock, and oil/water surface areas will be determined by advanced petrographic analysis and the surface free energy which drives spontaneous imbibition will be determined as a function of increase in wetting phase saturation. The inherent loss in surface free energy resulting from capillary instabilities at the microscopic (pore level) scale will be distinguished from the decrease in surface free energy that drives spontaneous imbibition. A mathematical network/numerical model will be developed and tested against experimental results of recovery versus time over broad variation of key factors such as rock properties, fluid phase viscosities, sample size, shape and boundary conditions. Two fundamentally important, but not previously considered, parameters of spontaneous imbibition, the capillary pressure acting to oppose production of oil at the outflow face and the pressure in the nonwetting phase at the no-flow boundary versus time, will also be measured and modeled. Simulation and network models will also be tested against special case solutions provided by analytic models. In the second stage of the project, application of the fundamental concepts developed in the first stage of the project will be demonstrated. The fundamental ideas, measurements, and analytic/numerical modeling will be applied to mixed-wet rocks. Imbibition measurements will include novel sensitive pressure measurements designed to elucidate the basic mechanisms that determine induction time and drive the very slow rate of spontaneous imbibition commonly observed for mixed-wet rocks. In further demonstration of concepts, three approaches to improved oil recovery from fractured reservoirs will be tested; use of surfactants to promote imbibition in oil wet rocks by wettability alteration: manipulation of injection brine composition: reduction of the capillary back pressure which opposes production of oil at the fracture face.

  2. FUNDAMENTALS OF RESERVOIR SURFACE ENERGY AS RELATED TO SURFACE PROPERTIES, WETTABILITY, CAPILLARY ACTION, AND OIL RECOVERY FROM FRACTURED RESERVOIRS BY SPONTANEOUS IMBIBITION

    SciTech Connect

    Norman R. Morrow

    2004-05-01

    The objective of this project is to increase oil recovery from fractured reservoirs through improved fundamental understanding of the process of spontaneous imbibition by which oil is displaced from the rock matrix into the fractures. Spontaneous imbibition is fundamentally dependent on the reservoir surface free energy but this has never been investigated for rocks. In this project, the surface free energy of rocks will be determined by using liquids that can be solidified within the rock pore space at selected saturations. Thin sections of the rock then provide a two-dimensional view of the rock minerals and the occupant phases. Saturations and oil/rock, water/rock, and oil/water surface areas will be determined by advanced petrographic analysis and the surface free energy which drives spontaneous imbibition will be determined as a function of increase in wetting phase saturation. The inherent loss in surface free energy resulting from capillary instabilities at the microscopic (pore level) scale will be distinguished from the decrease in surface free energy that drives spontaneous imbibition. A mathematical network/numerical model will be developed and tested against experimental results of recovery versus time over broad variation of key factors such as rock properties, fluid phase viscosities, sample size, shape and boundary conditions. Two fundamentally important, but not previously considered, parameters of spontaneous imbibition, the capillary pressure acting to oppose production of oil at the outflow face and the pressure in the nonwetting phase at the no-flow boundary versus time, will also be measured and modeled. Simulation and network models will also be tested against special case solutions provided by analytic models. In the second stage of the project, application of the fundamental concepts developed in the first stage of the project will be demonstrated. The fundamental ideas, measurements, and analytic/numerical modeling will be applied to mixed-wet rocks. Imbibition measurements will include novel sensitive pressure measurements designed to elucidate the basic mechanisms that determine induction time and drive the very slow rate of spontaneous imbibition commonly observed for mixed-wet rocks. In further demonstration of concepts, three approaches to improved oil recovery from fractured reservoirs will be tested; use of surfactants to promote imbibition in oil wet rocks by wettability alteration: manipulation of injection brine composition: reduction of the capillary back pressure which opposes production of oil at the fracture face.

  3. FUNDAMENTALS OF RESERVOIR SURFACE ENERGY AS RELATED TO SURFACE PROPERTIES, WETTABILITY, CAPILLARY ACTION, AND OIL RECOVERY FROM FRACTURED RESERVOIRS BY SPONTANEOUS IMBIBITION

    SciTech Connect

    Norman R. Morrow; Herbert Fischer; Yu Li; Geoffrey Mason; Douglas Ruth; Siddhartha Seth; Peigui Yin; Shaochang Wo

    2005-04-01

    The objective of this project is to increase oil recovery from fractured reservoirs through improved fundamental understanding of the process of spontaneous imbibition by which oil is displaced from the rock matrix into the fractures. Spontaneous imbibition is fundamentally dependent on the reservoir surface free energy but this has never been investigated for rocks. In this project, the surface free energy of rocks will be determined by using liquids that can be solidified within the rock pore space at selected saturations. Thin sections of the rock then provide a two-dimensional view of the rock minerals and the occupant phases. Saturations and oil/rock, water/rock, and oil/water surface areas will be determined by advanced petrographic analysis and the surface free energy which drives spontaneous imbibition will be determined as a function of increase in wetting phase saturation. The inherent loss in surface free energy resulting from capillary instabilities at the microscopic (pore level) scale will be distinguished from the decrease in surface free energy that drives spontaneous imbibition. A mathematical network/numerical model will be developed and tested against experimental results of recovery versus time over broad variation of key factors such as rock properties, fluid phase viscosities, sample size, shape and boundary conditions. Two fundamentally important, but not previously considered, parameters of spontaneous imbibition, the capillary pressure acting to oppose production of oil at the outflow face and the pressure in the nonwetting phase at the no-flow boundary versus time, will also be measured and modeled. Simulation and network models will also be tested against special case solutions provided by analytic models. In the second stage of the project, application of the fundamental concepts developed in the first stage of the project will be demonstrated. The fundamental ideas, measurements, and analytic/numerical modeling will be applied to mixed-wet rocks. Imbibition measurements will include novel sensitive pressure measurements designed to elucidate the basic mechanisms that determine induction time and drive the very slow rate of spontaneous imbibition commonly observed for mixed-wet rocks. In further demonstration of concepts, three approaches to improved oil recovery from fractured reservoirs will be tested; use of surfactants to promote imbibition in oil wet rocks by wettability alteration: manipulation of injection brine composition: reduction of the capillary back pressure which opposes production of oil at the fracture face.

  4. Fundamentals of reservoir surface energy as related to surface properties, wettability, capillary action, and oil recovery from fractured reservoirs by spontaneous imbibition

    SciTech Connect

    Norman R. Morrow; Herbert Fischer; Yu Li; Geoffrey Mason; Douglas Ruth; Siddhartha Seth; Jason Zhengxin Tong; Peigui Yin; Shaochang Wo

    2006-06-08

    The objective of this project is to increase oil recovery from fractured reservoirs through improved fundamental understanding of the process of spontaneous imbibition by which oil is displaced from the rock matrix into the fractures. Spontaneous imbibition is fundamentally dependent on the reservoir surface free energy but this has never been investigated for rocks. In this project, the surface free energy of rocks will be determined by using liquids that can be solidified within the rock pore space at selected saturations. Thin sections of the rock then provide a two-dimensional view of the rock minerals and the occupant phases. Saturations and oil/rock, water/rock, and oil/water surface areas will be determined by advanced petrographic analysis and the surface free energy which drives spontaneous imbibition will be determined as a function of increase in wetting phase saturation. The inherent loss in surface free energy resulting from capillary instabilities at the microscopic (pore level) scale will be distinguished from the decrease in surface free energy that drives spontaneous imbibition. A mathematical network/numerical model will be developed and tested against experimental results of recovery versus time over broad variation of key factors such as rock properties, fluid phase viscosities, sample size, shape and boundary conditions. Two fundamentally important, but not previously considered, parameters of spontaneous imbibition, the capillary pressure acting to oppose production of oil at the outflow face and the pressure in the non-wetting phase at the no-flow boundary versus time, will also be measured and modeled. Simulation and network models will also be tested against special case solutions provided by analytic models. In the second stage of the project, application of the fundamental concepts developed in the first stage of the project will be demonstrated. The fundamental ideas, measurements, and analytic/numerical modeling will be applied to mixed-wet rocks. Imbibition measurements will include novel sensitive pressure measurements designed to elucidate the basic mechanisms that determine induction time and drive the very slow rate of spontaneous imbibition commonly observed for mixed-wet rocks. In further demonstration of concepts, three approaches to improved oil recovery from fractured reservoirs will be tested; use of surfactants to promote imbibition in oil wet rocks by wettability alteration: manipulation of injection brine composition: reduction of the capillary back pressure which opposes production of oil at the fracture face.

  5. Fundamentals of Reservoir Surface Energy as Related to Surface Properties, Wettability, Capillary Action and Oil Recovery from Fractured Reservoirs by Spontaneous Imbibition

    SciTech Connect

    Norman R. Morrow; Herbert Fischer; Yu Li; Geoffrey Mason; Douglas Ruth; Peigui Yin; Shaochang Wo

    2006-12-08

    The objective of this project is to increase oil recovery from fractured reservoirs through improved fundamental understanding of the process of spontaneous imbibition by which oil is displaced from the rock matrix into the fractures. Spontaneous imbibition is fundamentally dependent on the reservoir surface free energy but this has never been investigated for rocks. In this project, the surface free energy of rocks will be determined by using liquids that can be solidified within the rock pore space at selected saturations. Thin sections of the rock then provide a two-dimensional view of the rock minerals and the occupant phases. Saturations and oil/rock, water/rock, and oil/water surface areas will be determined by advanced petrographic analysis and the surface free energy which drives spontaneous imbibition will be determined as a function of increase in wetting phase saturation. The inherent loss in surface free energy resulting from capillary instabilities at the microscopic (pore level) scale will be distinguished from the decrease in surface free energy that drives spontaneous imbibition. A mathematical network/numerical model will be developed and tested against experimental results of recovery versus time over broad variation of key factors such as rock properties, fluid phase viscosities, sample size, shape and boundary conditions. Two fundamentally important, but not previously considered, parameters of spontaneous imbibition, the capillary pressure acting to oppose production of oil at the outflow face and the pressure in the non-wetting phase at the no-flow boundary versus time, will also be measured and modeled. Simulation and network models will also be tested against special case solutions provided by analytic models. In the second stage of the project, application of the fundamental concepts developed in the first stage of the project will be demonstrated. The fundamental ideas, measurements, and analytic/numerical modeling will be applied to mixed-wet rocks. Imbibition measurements will include novel sensitive pressure measurements designed to elucidate the basic mechanisms that determine induction time and drive the very slow rate of spontaneous imbibition commonly observed for mixed-wet rocks. In further demonstration of concepts, three approaches to improved oil recovery from fractured reservoirs will be tested; use of surfactants to promote imbibition in oil wet rocks by wettability alteration: manipulation of injection brine composition: reduction of the capillary back pressure which opposes production of oil at the fracture face.

  6. FUNDAMENTALS OF RESERVOIR SURFACE ENERGY AS RELATED TO SURFACE PROPERTIES, WETTABILITY, CAPILLARY ACTION, AND OIL RECOVERY FROM FRACTURED RESERVOIRS BY SPONTANEOUS IMBIBITION

    SciTech Connect

    Norman R. Morrow; Herbert Fischer; Yu Li; Geoffrey Mason; Douglas Ruth; Siddhartha Seth; Peigui Yin; Shaochang Wo

    2004-10-01

    The objective of this project is to increase oil recovery from fractured reservoirs through improved fundamental understanding of the process of spontaneous imbibition by which oil is displaced from the rock matrix into the fractures. Spontaneous imbibition is fundamentally dependent on the reservoir surface free energy but this has never been investigated for rocks. In this project, the surface free energy of rocks will be determined by using liquids that can be solidified within the rock pore space at selected saturations. Thin sections of the rock then provide a two-dimensional view of the rock minerals and the occupant phases. Saturations and oil/rock, water/rock, and oil/water surface areas will be determined by advanced petrographic analysis and the surface free energy which drives spontaneous imbibition will be determined as a function of increase in wetting phase saturation. The inherent loss in surface free energy resulting from capillary instabilities at the microscopic (pore level) scale will be distinguished from the decrease in surface free energy that drives spontaneous imbibition. A mathematical network/numerical model will be developed and tested against experimental results of recovery versus time over broad variation of key factors such as rock properties, fluid phase viscosities, sample size, shape and boundary conditions. Two fundamentally important, but not previously considered, parameters of spontaneous imbibition, the capillary pressure acting to oppose production of oil at the outflow face and the pressure in the nonwetting phase at the no-flow boundary versus time, will also be measured and modeled. Simulation and network models will also be tested against special case solutions provided by analytic models. In the second stage of the project, application of the fundamental concepts developed in the first stage of the project will be demonstrated. The fundamental ideas, measurements, and analytic/numerical modeling will be applied to mixed-wet rocks. Imbibition measurements will include novel sensitive pressure measurements designed to elucidate the basic mechanisms that determine induction time and drive the very slow rate of spontaneous imbibition commonly observed for mixed-wet rocks. In further demonstration of concepts, three approaches to improved oil recovery from fractured reservoirs will be tested; use of surfactants to promote imbibition in oil wet rocks by wettability alteration: manipulation of injection brine composition: reduction of the capillary back pressure which opposes production of oil at the fracture face.

  7. Fundamentals of Reservoir Surface Energy as Related to Surface Properties, Wettability, Capillary Action, and Oil Recovery from Fractured Reservoirs by Spontaneous Imbibition

    SciTech Connect

    Norman Morrow; Herbert Fischer; Yu Li; Geoffrey Mason; Douglas Ruth; Siddhartha Seth; Zhengxin Tong; Evren Unsal; Siluni Wickramathilaka; Shaochang Wo; Peigui Yin

    2008-06-30

    The objective of this project is to increase oil recovery from fractured reservoirs through improved fundamental understanding of the process of spontaneous imbibition by which oil is displaced from the rock matrix into the fractures. Spontaneous imbibition is fundamentally dependent on the reservoir surface free energy but this has never been investigated for rocks. In this project, the surface free energy of rocks will be determined by using liquids that can be solidified within the rock pore space at selected saturations. Thin sections of the rock then provide a two-dimensional view of the rock minerals and the occupant phases. Saturations and oil/rock, water/rock, and oil/water surface areas will be determined by advanced petrographic analysis and the surface free energy which drives spontaneous imbibition will be determined as a function of increase in wetting phase saturation. The inherent loss in surface free energy resulting from capillary instabilities at the microscopic (pore level) scale will be distinguished from the decrease in surface free energy that drives spontaneous imbibition. A mathematical network/numerical model will be developed and tested against experimental results of recovery versus time over broad variation of key factors such as rock properties, fluid phase viscosities, sample size, shape and boundary conditions. Two fundamentally important, but not previously considered, parameters of spontaneous imbibition, the capillary pressure acting to oppose production of oil at the outflow face and the pressure in the non-wetting phase at the no-flow boundary versus time, will also be measured and modeled. Simulation and network models will also be tested against special case solutions provided by analytic models. In the second stage of the project, application of the fundamental concepts developed in the first stage of the project will be demonstrated. The fundamental ideas, measurements, and analytic/numerical modeling will be applied to mixed-wet rocks. Imbibition measurements will include novel sensitive pressure measurements designed to elucidate the basic mechanisms that determine induction time and drive the very slow rate of spontaneous imbibition commonly observed for mixed-wet rocks. In further demonstration of concepts, three approaches to improved oil recovery from fractured reservoirs will be tested; use of surfactants to promote imbibition in oil wet rocks by wettability alteration: manipulation of injection brine composition: reduction of the capillary back pressure which opposes production of oil at the fracture face.

  8. Fundamentals of reservoir surface energy as related to surface properties, wettability, capillary action, and oil recovery from fractured reservoirs by spontaneous imbibition

    SciTech Connect

    Norman R. Morrow; Herbert Fischer; Yu Li; Geoffrey Mason; Douglas Ruth; Siddhartha Seth; Jason Zhengxin Tong; Peigui Yin; Shaochang Wo

    2006-02-01

    The objective of this project is to increase oil recovery from fractured reservoirs through improved fundamental understanding of the process of spontaneous imbibition by which oil is displaced from the rock matrix into the fractures. Spontaneous imbibition is fundamentally dependent on the reservoir surface free energy but this has never been investigated for rocks. In this project, the surface free energy of rocks will be determined by using liquids that can be solidified within the rock pore space at selected saturations. Thin sections of the rock then provide a two-dimensional view of the rock minerals and the occupant phases. Saturations and oil/rock, water/rock, and oil/water surface areas will be determined by advanced petrographic analysis and the surface free energy which drives spontaneous imbibition will be determined as a function of increase in wetting phase saturation. The inherent loss in surface free energy resulting from capillary instabilities at the microscopic (pore level) scale will be distinguished from the decrease in surface free energy that drives spontaneous imbibition. A mathematical network/numerical model will be developed and tested against experimental results of recovery versus time over broad variation of key factors such as rock properties, fluid phase viscosities, sample size, shape and boundary conditions. Two fundamentally important, but not previously considered, parameters of spontaneous imbibition, the capillary pressure acting to oppose production of oil at the outflow face and the pressure in the nonwetting phase at the no-flow boundary versus time, will also be measured and modeled. Simulation and network models will also be tested against special case solutions provided by analytic models. In the second stage of the project, application of the fundamental concepts developed in the first stage of the project will be demonstrated. The fundamental ideas, measurements, and analytic/numerical modeling will be applied to mixed-wet rocks. Imbibition measurements will include novel sensitive pressure measurements designed to elucidate the basic mechanisms that determine induction time and drive the very slow rate of spontaneous imbibition commonly observed for mixed-wet rocks. In further demonstration of concepts, three approaches to improved oil recovery from fractured reservoirs will be tested; use of surfactants to promote imbibition in oil wet rocks by wettability alteration: manipulation of injection brine composition: reduction of the capillary back pressure which opposes production of oil at the fracture face.

  9. Silicon ribbon growth by a capillary action shaping technique

    NASA Technical Reports Server (NTRS)

    Schwuttke, G. H.; Ciszek, T. F.; Kran, A.; Yang, K.

    1977-01-01

    The crystal-growth method under investigation is a capillary action shaping technique. Meniscus shaping for the desired ribbon geometry occurs at the vertex of a wettable dye. As ribbon growth depletes the melt meniscus, capillary action supplies replacement material. The configuration of the technique used in our initial studies is shown. The crystal-growth method has been applied to silicon ribbons it was found that substantial improvements in ribbon surface quality could be achieved with a higher melt meniscus than that attainable with the EFG technique.

  10. Patterning of wettability for controlling capillary-driven flow in closed channels.

    PubMed

    O'Loughlin, Muireann; Priest, Craig; Popescu, Mihail N; Ralston, John

    2013-07-15

    Glass capillaries are prepared with well-defined regions of tuneable wettability on the interior walls using an inexpensive and simple approach. A homogeneous layer of hydrophilic TiO2 nanoparticles is adsorbed on the capillary wall and chemically hydrophobized using octadecyltrihydrosilane (OTHS). The hydrophobic OTHS monolayer is then patterned by spatially-selective removal of the OTHS via TiO2-catalysed decomposition by ultraviolet irradiation. By patterning the capillaries with hydrophilic-hydrophobic rings, modulated penetration of a liquid (glycerol, in this study) can be achieved. For given wettability contrast, the penetration dynamics and equilibrium rise heights are very sensitive to the characteristic length-scale of the pattern, and may offer greater, time-dependent sampling control in fluidic devices. PMID:23660024

  11. Prediction of two-phase capillary pressure-saturation relationships in fractional wettability systems.

    PubMed

    O'Carroll, Denis M; Abriola, Linda M; Polityka, Catherine A; Bradford, Scott A; Demond, Avery H

    2005-05-01

    Capillary pressure/saturation data are often difficult and time consuming to measure, particularly for non-water-wetting porous media. Few capillary pressure/saturation predictive models, however, have been developed or verified for the range of wettability conditions that may be encountered in the natural subsurface. This work presents a new two-phase capillary pressure/saturation model for application to the prediction of primary drainage and imbibition relations in fractional wettability media. This new model is based upon an extension of Leverett scaling theory. Analysis of a series of DNAPL/water experiments, conducted for a number of water/intermediate and water/organic fractional wettability systems, reveals that previous models fail to predict observed behavior. The new Leverett-Cassie model, however, is demonstrated to provide good representations of these data, as well as those from two earlier fractional wettability studies. The Leverett-Cassie model holds promise for field application, based upon its foundation in fundamental scaling principles, its requirement for relatively few and physically based input parameters, and its applicability to a broad range of wetting conditions. PMID:15854719

  12. Capillary, wettability and interfacial dynamics in polymer electrolyte fuel cells

    SciTech Connect

    Mukherjee, Partha P

    2009-01-01

    In the present scenario of a global initiative toward a sustainable energy future, the polymer electrolyte fuel cell (PEFC) has emerged as one of the most promising alternative energy conversion devices for different applications. Despite tremendous progress in recent years, a pivotal performance/durability limitation in the PEFC arises from liquid water transport, perceived as the Holy Grail in PEFC operation. The porous catalyst layer (CL), fibrous gas diffusion layer (GDL) and flow channels play a crucial role in the overall PEFC performance due to the transport limitation in the presence of liquid water and flooding phenomena. Although significant research, both theoretical and experimental, has been performed, there is serious paucity of fundamental understanding regarding the underlying structure-transport-performance interplay in the PEFC. The inherent complex morphologies, micro-scale transport physics involving coupled multiphase, multicomponent, electrochemically reactive phenomena and interfacial interactions in the constituent components pose a formidable challenge. In this paper, the impact of capillary transport, wetting characteristics and interfacial dynamics on liquid water transport is presented based on a comprehensive mesoscopic modeling framework with the objective to gain insight into the underlying electrodynamics, two-phase dynamics and the intricate structure-transport-interface interactions in the PEFC.

  13. Silicon ribbon growth by a capillary action shaping technique

    NASA Technical Reports Server (NTRS)

    Schwuttke, G. H.; Schwuttke, G. H.; Ciszek, T. F.; Kran, A.

    1977-01-01

    Substantial improvements in ribbon surface quality are achieved with a higher melt meniscus than that attainable with the film-fed (EFG) growth technique. A capillary action shaping method is described in which meniscus shaping for the desired ribbon geometry occurs at the vertex of a wettable die. As ribbon growth depletes the melt meniscus, capillary action supplies replacement material. Topics discussed cover experimental apparatus and growth procedures; die materials investigations, fabrication and evaluation; process development for 25 mm, 38 mm, 50 mm and 100 mm silicon ribbons; and long grain direct solidification of silicon. Methods for the structural and electrical characterization of cast silicon ribbons are assessed as well as silicon ribbon technology for the 1978 to 1986 period.

  14. Direct determination of contact angles of model soils in comparison with wettability characterization by capillary rise

    NASA Astrophysics Data System (ADS)

    Ramírez-Flores, Juan Carlos; Bachmann, Jörg; Marmur, Abraham

    2010-03-01

    SummaryAn accurate method to determine contact angles (CA) of soils as a measure of water repellency is still missing. In the present research, we evaluated and compared different methods to determine the CA of dry soil samples. Experiments were made by using a set of porous materials (silt, sand and glass beads) with different levels of water repellency. The CAs were measured with the Capillary Rise Method ( θCRM; liquid penetration into a 3-d system), the Wilhelmy plate method ( θWPM; measurement of capillary forces acting on a plane sample) and the Sessile Drop Method ( θSDM; optical CA analysis of drop contour on a plane sample). Results were compared with the CAs calculated from capillary rise in long vertical columns ( θECR), where liquid profiles of the final capillary rise of water and ethanol, respectively, were used to derive the contact angle under the assumed equilibrium conditions. The results showed the overestimation of the CA by using the well established bi-liquid CRM technique for porous materials, in particular for material with a low degree of water repellency (CA < 40°) and for the finer textured materials. In contrast, a variant of the Wilhelmy plate method, i.e. the cosine-averaged advancing CA and receding CA ( θEWPM), as well as the Sessile Drop CA, θSDM, were close to the ones of θECR. We concluded that θEWPM and θSDM are apparent CA, but nevertheless able to predict the impact of wettability on the final capillary rise which is affected by pore topology as well as by wettability.

  15. Capillary pressure spectrometry: Toward a new method for the measurement of the fractional wettability of porous media

    NASA Astrophysics Data System (ADS)

    Sygouni, Varvara; Tsakiroglou, Christos D.; Payatakes, Alkiviades C.

    2006-05-01

    A transparent porous medium of controlled fractional wettability is fabricated by mixing intermediate-wet glass microspheres with strongly oil-wet polytetrafluouroethylene microspheres, and packing them between two transparent glass plates. Silicon oil is displaced by water, the growth pattern is video-recorded, and the transient response of the pressure drop across the pore network is measured for various fractions of oil-wet particles. The measured global capillary pressure fluctuates as the result of the variation of the equilibrium curvature of menisci between local maxima and local minima. With the aid of wavelets, the transient response of the capillary pressure is transformed to a capillary pressure spectrum (CPS). The peaks of the CPS are used to identify the most significant flow events and correlate their amplitude with the spatial distribution of fractional wettability. The flow events are closely related with the fluctuations of the capillary pressure and are classified into three main categories: motion in pore clusters, generation/expansion of capillary fingers, coalescence of interfaces. The amplitude of the peaks of CPS is related quasilinearly with a local coefficient of fractional wettability presuming that the same class of flow events is concerned. Approximate calculations of the maximum meniscus curvature in pores of converging-diverging geometry and uniform wettability in combination with simple mixing laws predict satisfactorily the experimentally measured average prebreakthrough capillary pressure as a function of the fraction of the oil-wet particles.

  16. Modelling the effect of pore structure and wetting angles on capillary rise in soils having different wettabilities

    NASA Astrophysics Data System (ADS)

    Czachor, Henryk

    2006-09-01

    SummaryCapillary rise in axis symmetrical sinusoidal capillary (SC) has been modelled. Analytical formula for meniscus radius, capillary pressure and meniscus rate in SC have been found. Capillary shape described by wall waviness highly influences all of them. The limit between wettability and repellency in such capillary is described by critical value of contact angle θc which is related to the pore geometry by the equation ctg( θc) = πd2, where d2 - pore wall waviness. Kinetics of capillary rise in sinusoidal capillary has been determined by numerical integration of meniscus rate equation for a wide range of pore wall waviness and several values of contact angles. Application of Washburn theory to the data obtained from simulation gives the contact angle value much higher than the true one. In contrast, the obtained pore radius value is usually well correlated with capillary neck. However, in some cases a calculated radius can be even smaller. Above conclusions have been qualitatively confirmed by experiments performed on glass beads and soils. Contact angle measured on flat glass was 27.4°. The calculations concerning the data from capillary rise experiments on 90-1000 μm fraction of glass powder and Washburn theory gave values ca. 80°. The contact angle values for peat soils and loamy sand have close values, which supports the opinion that non-cylindrical shape of soil pores highly influences both the wettability/repellency and the water flux in soils.

  17. Rapid retraction of microvolume aqueous plugs traveling in a wettable capillary

    NASA Astrophysics Data System (ADS)

    Kim, Jinho; O'Neill, John D.; Vunjak-Novakovic, Gordana

    2015-10-01

    We report a transport behavior—specifically, rapid retraction movement—of small (˜μL) deionized water plugs traveling in series within a small wettable tubular geometry. In this study, two water plugs separated by a certain distance in a dry cylindrical glass capillary were moved by positive pressure airflow applied at the tube inlet. As the plugs travel, a thin aqueous film is generated between the plugs as a result of the leading plug's aqueous deposition onto the inner surface of the tube. The leading plug continuously loses volume by film deposition onto the surface and eventually ruptures. Then, the lagging plug quickly travels the distance initially separating the two plugs (plug retraction). Our studies show that the rapid retraction of the lagging plug is caused by surface tension in addition to the positive pressure applied. Furthermore, the plug retraction speed is strongly affected by tube radius and the distance between the plugs.

  18. Spontaneous and forced imbibition of aqueous wettability altering surfactant solution into an initially oil-wet capillary.

    PubMed

    Hammond, Paul S; Unsal, Evren

    2009-11-01

    Unforced invasion of wettability-altering aqueous surfactant solutions into an initially oil-filled oil-wet capillary tube has been observed to take place very slowly, and because this system is an analogue for certain methods of improved oil recovery from naturally fractured oil-wet reservoirs, it is important to identify the rate-controlling processes. We used a model for the process published by Tiberg et al. ( Tiberg , F. , Zhmud , B. , Hallstensson , K. and Von Bahr , M. Phys. Chem. Chem. Phys. 2000 , 2 , 5189 - 5196 ) and modified it for forced imbibitions. We show that when applied pressure differences are not too large invasion rates are controlled at large times by the value of the bulk diffusion coefficient for surfactant in the aqueous phase and at early times by the resistance to transfer of surfactant from the oil-water meniscus onto the walls of the capillary. For realistic values of the bulk diffusion coefficient, invasion rates are indeed slow, as observed. The model also predicts that the oil-water-solid contact angle during unforced displacement is close to pi/2, and so, the displacement occurs in a state of near-neutral wettability with the rate of invasion controlled by the rate of surfactant diffusion rather than a balance between capillary forces and viscous resistance. Under forced conditions, the meniscus moves faster, but the same kinds of dynamical balances between the various processes as were found in the spontaneous case operate. Once the capillary threshold pressure for entry into the initial oil-wet tube is exceeded, the effect of pressure on velocity becomes more significant, there is not sufficient time for the surfactant molecules to transfer in great quantity from the meniscus to the solid surface, and wettability alteration is then no longer important. PMID:19673494

  19. Influence of Wettability on Dense Nonaqueous Phase Liquid (DNAPL) Capillary Hysteresis Behavior and Relative Permeability in Saturated Porous Media

    NASA Astrophysics Data System (ADS)

    Ocarroll, D. M.; Polityka, C. A.; Phelan, T. J.; Abriola, L. M.

    2003-04-01

    Alhough it is commonly assumed that subsurface soils are completely water-wet, variations in wettability are likely in the contaminated subsurface. Dense nonaqueous phase liquids (DNAPLs) have often been released as part of acidic or basic mixtures containing surface active compounds. These mixtures can render subsurface soils intermediate to organic-wet. In addition natural soils have a variety of wetting characteristics. This works explores the effects of solid wettability on capillary pressure/saturation and relative permeability/saturation constitutive relationships for DNAPL/water systems. Tetrachloroethene (PCE) is used as a representative DNAPL in these experiments. A series of capillary pressure/saturation experiments and multistep column outflow experiments were conducted to estimate capillary retention and relative permeability functions for PCE in media with various wetting properties. Relative permeability/saturation parameters were quantified utilizing a multiphase flow simulator coupled with an inverse optimization routine. The optimization routine minimizes the square difference between experimental and simulated outflow by varying the constitutive parameters. Capillary pressure/saturation data, generated in small pressure cell experiments, facilitate independent verification of the retention functions fit to the multistep outflow experiments. Primary drainage, imbibition, and scanning curves are presented for water, intermediate and organic-wet F35/F50/F70/F110 sand. The utility of using Leverett scaling, in conjunction with independently measured contact angles, to scale primary drainage curves is assessed for these sands. Finally, results from the outflow experiments indicate that traditional capillary-based predictive models fail to capture observed relative permeability behavior at endpoint saturations.

  20. Influence of the heterogeneous wettability on capillary trapping in glass-beads monolayers: Comparison between experiments and the invasion percolation theory.

    PubMed

    Geistlinger, Helmut; Ataei-Dadavi, Iman

    2015-12-01

    We demonstrated that a change in the surface chemistry, i.e., a change from heterogeneous to homogeneous wettability, can dramatically influence capillary trapping, i.e., from significant trapping (?5%) to no trapping. Furthermore, the displacement process (water displaces air) in glass-beads monolayer with heterogeneous wettability shows (i) a heterogeneous morphology and a stochastic advancement of the interface in the highly ordered triangular structure, (ii) capillary trapping of a broad variety of gas clusters, notably large ganglia-like and network-like gas clusters, and (iii) a variation in the contact angle between 30 and 100. In the second part of this paper, we compared the experimental results of capillary trapping for the monolayer that possesses a heterogeneous wettability with predictions from the invasion percolation theory and found excellent agreement, e.g., that the experimental cluster size distribution can be described by a universal power-law with an averaged exponent ?(exp)=2.06; that is a deviation of 5% from the theoretical value. This agreement indicates that capillary trapping within the 2D-monolayer is governed by the 3D critical exponent; therefore, the monolayer shows a trapping behavior similar to a 3D-porous media. We proposed an analytical approach to calculate the mass transfer rate constant using functional relationships predicted by percolation theory and compare this result with results derived from empirical relationships, which are often used for modelling the dissolution process of trapped non-wetting phases. PMID:26298285

  1. Capillary pressure and wettability behavior of CO{sub 2} sequestration in coal at elevated pressures

    SciTech Connect

    Plug, W.J.; Mazumder, S.; Bruining, J.

    2008-12-15

    Enhanced coalbed-methane (ECBM) recovery combines recovery of methane (CH{sub 4}) from coal seams with storage of carbon dioxide (CO{sub 2}). The efficiency of ECBM recovery depends on the CO{sub 2} transfer rate between the macrocleats, via the microcleats to the coal matrix. Diffusive transport of CO{sub 2} in the small cleats is enhanced when the coal is CO{sub 2}-wet. Indeed, for water-wet conditions, the small fracture system is filled with water and the rate of CO{sub 2} sorption and CH{sub 4} desorption is affected by slow diffusion of CO{sub 2}. This work investigates the wetting behavior of coal using capillary pressures between CO{sub 2} and water, measured continuously as a function of water saturation at in-situ conditions. To facilitate the interpretation of the coal measurements, we also obtain capillary pressure curves for unconsolidated-sand samples. For medium- and high-rank coal, the primary drainage capillary pressure curves show a water-wet behavior. Secondary forced-imbibition experiments show that the medium-rank coal becomes CO{sub 2}-wet as the CO{sub 2} pressure increases. High-rank coal is CO{sub 2}-wet during primary imbibition. The imbibition behavior is in agreement with contact-angle measurements. Hence, we conclude that imbibition tests provide the practically relevant data to evaluate the wetting properties of coal.

  2. Spontaneous imbibition of surfactant solution into an oil-wet capillary: wettability restoration by surfactant-contaminant complexation.

    PubMed

    Hammond, Paul S; Unsal, Evren

    2011-04-19

    For a given type of rock, the effectiveness of oil recovery through wettability alteration is highly dependent upon the nature of the water-soluble surfactant used. Different mechanisms have been proposed by others to explain wettability alteration by surfactants, and understanding the process is crucial to improve recovery performance. Known mechanisms include (1) surfactant adsorption onto the oil-wet solid surface (coating mechanism) and (2) surfactant molecules complexing with contaminant molecules from the crude oil which are adsorbed on the rock surface so as to strip them off (cleaning mechanism). With the second mechanism, the wettability is restored by lifting the contaminant layer away, exposing the rock surface which was originally water-wet. We previously focused on the numerical modeling of the surfactant coating mechanism (Hammond and Unsal Langmuir2009, 25, 12591; 2010, 26, 6206), and we now present a numerical study for the cleaning process. Our new model shows that when a wettability altering surfactant solution is allowed to imbibe spontaneously and acts by the cleaning process, the meniscus advances more rapidly than when there was wettability alteration by coating alone. In our previous model there was a concentration threshold below which imbibition was not possible. That threshold arose because a finite amount of surfactant needs to be adsorbed onto the oil-wet surface to change the contact angle to a water-wet value, but the maximum amount that can be absorbed is limited by the requirement that it be in equilibrium with the surfactant concentration near the meniscus. In the new model, with the cleaning mechanism there is no such threshold, since the cleaning process is driven by the surfactant flux into the vicinity of the advancing meniscus rather than the surfactant concentration there. As long as there are surfactant molecules present in the aqueous solution, the flux is nonzero and molecule pairs can form and alter the wettability by removing the contaminant from the oil-wet surface. However, under very low surfactant concentrations, the process is extremely slow compared to at higher concentrations. PMID:21428422

  3. Silicon ribbon growth by a capillary action shaping technique

    NASA Technical Reports Server (NTRS)

    Schwuttke, G. H.; Ciszek, T. F.; Kran, A.

    1976-01-01

    The technique of silicon ribbon growth by the capillary action shaping is assessed for applicability to photovoltaic power device material. Ribbons 25 mm in width and up to 0.5 m in length have been grown from SiC dies, and some new characteristics of growth from such dies have been identified. Thermal modifiers have been studied, and systems were developed which reduce the frozen-in stress un silicon ribbons and improve the thickness uniformity of the ribbons. Preliminary spreading resistance measurements indicate that neither surface striations nor twin boundaries give rise to appreciable resistivity variations, but that large-angle grain boundaries cause local resistivity increases of up to 200%.

  4. High-resolution x-ray tomography imaging of supercritical CO2: Investigating capillary trapping under reservoir conditions and addressing wettability alteration

    NASA Astrophysics Data System (ADS)

    Andersson, L.; Herring, A. L.; Newell, D. L.; Carey, B.; Wildenschild, D.

    2013-12-01

    In geological carbon sequestration, CO2 is stored in a supercritical state in subsurface reservoirs. Deep saline aquifers are particularly attractive because of their abundance and potentially large storage volumes. Despite very broad research efforts there are still substantial uncertainties related to the effectiveness of the trapping processes controlling the permanent storage of CO2. After injection of CO2 the saline water (brine) will imbibe back and reoccupy the pore space as the buoyant CO2 moves upwards. Some of the CO2 will remain behind in a trapping mechanism known as capillary trapping that occurs as CO2 bubbles are isolated by the brine inside some of the pore space. The large-scale movement of the trapped CO2 within the brine is thereby prevented. Capillary trapping thus constitutes an important storage mechanism following CO2 injection until subsequent aqueous dissolution and precipitation of carbonate minerals depletes the reservoir of free-phase CO2. We present pressure-saturation curves derived from drainage and imbibition experiments with brine and supercritical CO2 at 1200 PSI and at 36C for Bentheimer sandstone cores. We compare the supercritical CO2 experiments with ambient pressure and temperature experiments using water and air (supercritical CO2 proxy fluid) for Bentheimer sandstone. The pressure-saturation curves are accompanied with quantitative results on non-wetting phase saturation, topology and connectivity as determined from three-dimensional (3D) images. The 3D data with a resolution of 4.65 ?m were derived from high-resolution synchrotron x-ray computed micro-tomography (CMT), collected at the GSECARS beam line 13-BM-D at the Advanced Photon Source, Argonne National Laboratory. Drainage and imbibition experiments, performed under ambient pressure and temperature conditions, indicate that the topology of the non-wetting phase after drainage correlates with the final trapping of the non-wetting phase, after imbibition. Pressure-saturation curves obtained for supercritical CO2 and water at reservoir conditions (1200 PSI and 36C), point towards a wettability alteration of the Bentheimer sandstone upon contact with supercritical CO2.

  5. [Action of calcium dobesilate on capillary fragility in diabetics].

    PubMed

    Beretta, P; Sartori, F

    1977-01-01

    Calcium dobesylate was administered for 30 days to diabetics with or without clinical signs referable to microangiopathy and increased capillary fragility unaccompanied by coagulation and haemostasis disturbances. Good results were observed in 90% of cases. It is felt that the drug can also be used in the tertiary prevention of systemic microangiopathy, as well as the medical management of diabetic retinopathy. PMID:603392

  6. Effect of wettability on light oil steamflooding

    SciTech Connect

    Olsen, D.K.

    1991-12-01

    This report summarizes NIPER's research on four interrelated topics for Light Oil Steamflooding. Four interrelated topics are described: The methodology for measuring capillary pressure and wettability at elevated temperature, the use of silylating agents to convert water-wet Berea sandstones or unconsolidated quartz sands to oil-wetted surfaces, the evaluation of the thermal hydrolytic stability of these oil-wet surfaces for possible use in laboratory studies using steam and hot water to recover oil, and the effect of porous media of different wettabilities on oil recovery where the porous media is first waterflooded and then steamflooded.

  7. Effect of wettability on light oil steamflooding

    SciTech Connect

    Olsen, D.K.

    1991-12-01

    This report summarizes NIPER`s research on four interrelated topics for Light Oil Steamflooding. Four interrelated topics are described: The methodology for measuring capillary pressure and wettability at elevated temperature, the use of silylating agents to convert water-wet Berea sandstones or unconsolidated quartz sands to oil-wetted surfaces, the evaluation of the thermal hydrolytic stability of these oil-wet surfaces for possible use in laboratory studies using steam and hot water to recover oil, and the effect of porous media of different wettabilities on oil recovery where the porous media is first waterflooded and then steamflooded.

  8. Wettability contrasts between fresh and weathered diesel fuels.

    PubMed

    Drake, Stephanie S; O'Carroll, Denis M; Gerhard, Jason I

    2013-01-01

    The remediation of non-aqueous phase liquid (NAPL) contaminated sites is impeded due to subsurface complexities, including wettability. Wettability quantifies which of two immiscible fluids preferentially coats a solid. At most contaminated sites water-wetting conditions are typically assumed despite mounting evidence that this is not always the case. In this study, wettability was examined for two NAPL samples of contrasting origin: a fresh and a field sample. Wettability was assessed through (i) cyclical, 'cumulative elapsed contact time' intrinsic contact angle measurements, (ii) interface jar tests, and (iii) cyclical, pseudo-static capillary pressure-saturation curves. The work as a whole demonstrated that while the fresh diesel sample was consistently water-wet, the field diesel sample exhibited repeatable cycles of wettability reversal between water drainage and imbibition. And while wettability hysteresis increased with contact time for the field diesel, the occurrence of wettability reversal at each change of saturation direction was independent of contact time. Such behavior is not easily assessed by standard wettability indices. Moreover, it contrasts with the permanent wettability alteration observed for complex organics (e.g., coal tar) observed in most studies. It is hypothesized that the cyclical wettability reversal is related to cyclical changes in intermediate pore wettability due to sorption of surface active compounds (causing NAPL-wetting imbibition) and rupturing of the soil grain water film (causing water-wet drainage). The wettability differences between the two NAPLs may be due to additives (i.e., a surfactant) in the original formulation and/or byproducts from subsurface weathering. These results support better characterization of site-specific wettability, improved model development and more realistic site conceptual models for improved remediation efforts. PMID:23159759

  9. Wettability contrasts between fresh and weathered diesel fuels

    NASA Astrophysics Data System (ADS)

    Drake, Stephanie S.; O'Carroll, Denis M.; Gerhard, Jason I.

    2013-01-01

    The remediation of non-aqueous phase liquid (NAPL) contaminated sites is impeded due to subsurface complexities, including wettability. Wettability quantifies which of two immiscible fluids preferentially coats a solid. At most contaminated sites water-wetting conditions are typically assumed despite mounting evidence that this is not always the case. In this study, wettability was examined for two NAPL samples of contrasting origin: a fresh and a field sample. Wettability was assessed through (i) cyclical, 'cumulative elapsed contact time' intrinsic contact angle measurements, (ii) interface jar tests, and (iii) cyclical, pseudo-static capillary pressure-saturation curves. The work as a whole demonstrated that while the fresh diesel sample was consistently water-wet, the field diesel sample exhibited repeatable cycles of wettability reversal between water drainage and imbibition. And while wettability hysteresis increased with contact time for the field diesel, the occurrence of wettability reversal at each change of saturation direction was independent of contact time. Such behavior is not easily assessed by standard wettability indices. Moreover, it contrasts with the permanent wettability alteration observed for complex organics (e.g., coal tar) observed in most studies. It is hypothesized that the cyclical wettability reversal is related to cyclical changes in intermediate pore wettability due to sorption of surface active compounds (causing NAPL-wetting imbibition) and rupturing of the soil grain water film (causing water-wet drainage). The wettability differences between the two NAPLs may be due to additives (i.e., a surfactant) in the original formulation and/or byproducts from subsurface weathering. These results support better characterization of site-specific wettability, improved model development and more realistic site conceptual models for improved remediation efforts.

  10. A study of heat transfer during steam condensation on a horizontal tube placed in granular material made of particles with different wettability of surface

    NASA Astrophysics Data System (ADS)

    Bogomolov, A. R.; Petrik, P. T.; Azikhanov, S. S.

    2009-07-01

    The dependence of the equivalent radius of a threshold channel on the diameter of particles during combined action of capillary and mass forces is experimentally obtained. Experimental data on heat transfer during steam condensation on a horizontal tube placed in well- and partially wettable granular layers are presented. It is shown that no enhancement of heat transfer occurs in these layers as compared with that in case of a plain tube.

  11. Wettability Control of Droplet Deposition and Detachment

    NASA Astrophysics Data System (ADS)

    Baret, Jean-Christophe; Brinkmann, Martin

    2006-04-01

    The conditions for droplet deposition on plane substrates are studied using electrowetting to continuously modulate the surface wettability. Droplets of controlled volume attached to the tip of a pipette are brought into contact with the surface. During retraction of the pipette the droplets are deposited or detach completely depending on volume and contact angle. The experimental limit of deposition in the contact angle or volume plane is in good agreement with analytical and numerical predictions obtained within the capillary model.

  12. Wettability of graphene

    NASA Astrophysics Data System (ADS)

    Parobek, David; Liu, Haitao

    2015-09-01

    The discovery of graphene has renewed the interest in the wettability of graphitic materials. Although graphene and graphite are long believed to be hydrophobic, recent studies have challenged this long-held belief. In addition, the unique structure of graphene also enabled new avenues to manipulate their wetting properties. This review highlights recent studies in these research areas with a special focus on the following topics: (1) intrinsic wettability of graphene; (2) manipulate the wettability of graphene by surface engineering; (3) theoretical studies of water-graphene interaction; and (4) cleaning of graphene.

  13. Wettability studies of morphine sulfate powders.

    PubMed

    Prestidge, C A; Tsatouhas, G

    2000-04-01

    A capillary penetration technique was used to determine the wettability of morphine sulfate powders by a range of wetting and partially wetting liquids. Wetting rates were found to be dependent on both the properties of the wetting liquid and the morphine sulfate batch. A number of liquids were established as perfectly wetting, and the critical surface tension for morphine sulfate wetting was estimated to be approximately 40 mN m(-1). Effective capillary radii for packed beds of morphine sulfate powders were determined in the range 0.3-0.6 microm; these are compared with particle size, shape and surface area data. From the Washburn approach, the advancing water-particle contact angles for the different morphine sulfate samples were determined to be in the range 57-79 degrees, with errors less than +/-3 degrees. Sessile drop measurements on the same samples were unable to determine reproducible equilibrium contact angles and could not differentiate between the batches. The role of surface chemistry, crystal morphology and crystal structure in controlling morphine sulfate powder wettability was explored by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and X-ray diffraction. Contact angles were shown to correlate with both the aspect ratio of the morphine sulfate crystals and the nitrogen-to-oxygen surface atomic concentration ratio, determined by SEM and XPS, respectively. The relative exposure of different crystal faces is considered to play an important role in controlling the wettability of morphine sulfate powders. PMID:10767569

  14. Thin films, asphaltenes, and reservoir wettability

    SciTech Connect

    Kaminsky, R.; Bergeron, V.; Radke, C.J. |

    1993-04-01

    Reservoir wettability impacts the success of oil recovery by waterflooding and other methods. To understand wettability and its alteration, thin-film forces in solid-aqueous-oil systems must be elucidated. Upon rupture of thick aqueous films separating the oil and rock phases, asphaltene components in the crude oil adsorb irreversibly on the solid surface, changing it from water-wet to oil-wet. Conditions of wettability alteration can be found by performing adhesion tests, in which an oil droplet is brought into contact with a solid surface. Exceeding a critical capillary pressure destabilizes the film, causing spontaneous film rupture to a molecularly adsorbed layer and oil adhesion accompanied by pinning at the three-phase contact line. The authors conduct adhesion experiments similar to those of Buckley and Morrow and simultaneously examine the state of the underlying thin film using optical microscopy and microinterferometry. Aqueous thin films between an asphaltic Orcutt crude oil and glass surfaces are studied as a function of aqueous pH and salinity. For the first time, they prove experimentally that strongly water-wet to strongly oil-wet wettability alteration and contact-angle pinning occur when thick aqueous films thin to molecularly adsorbed films and when the oil phase contains asphaltene molecules.

  15. The Measurement of Wettability

    ERIC Educational Resources Information Center

    Pirie, Brian J. S.; Gregory, David W.

    1973-01-01

    Discusses the use of a simple apparatus to measure contact angles between a liquid drop and a solid surface which are determining factors of wettability. Included are examples of applying this technique to various experimental situations. (CC)

  16. Capillary foams: highly stable bubbles formed by synergistic action of particles and immiscible liquid

    NASA Astrophysics Data System (ADS)

    Meredith, Carson; Zhang, Yi; Behrens, Sven

    2015-03-01

    Liquid foams are a familiar part of everyday life from beer and frothed milk to bubble baths; they also play important roles in enhanced oil recovery, lightweight packaging, and insulation. We report a new class of foams, obtained by frothing a suspension of colloidal particles in the presence of a small amount of an immiscible secondary liquid. A unique aspect of the new foams, termed capillary foams, is that suspended particles mediate spreading of a minority liquid around gas bubbles. The resulting mixed particle/liquid coating can stabilize bubbles against coalescence even when the particles alone cannot. We demonstrate the generality of capillary foams by forming them from a diverse set of particle/liquid combinations and rationalize the results with a simple free energy model. In addition to many applications as liquid foams, capillary foams can serve as precursors for hierarchically-structured solids with porosity on different length scales and with significant application potential.

  17. Wettability by Ionic Liquids.

    PubMed

    Liu, Hongliang; Jiang, Lei

    2016-01-01

    Ionic liquids (ILs) have become particularly attractive recently because they have demonstrated themselves to be important construction units in the broad fields of chemistry and materials science, from catalysis and synthesis to analysis and electrochemistry, from functional fluids to clean energy, from nanotechnology to functional materials. One of the greatest issues that determines the performance of ILs is the wettability of correlated surfaces. In this concept article, the key developments and issues in IL wettability are surveyed, including the electrowetting of ILs in gas-liquid-solid systems and liquid-liquid-solid systems, ILs as useful probe fluids, the superwettability of Ils, and future directions in IL wettability. This should generate extensive interest in the field and encourage more scientists to engage in this area to tackle its scientific challenges. PMID:26619157

  18. Drying patterns of porous media containing wettability contrasts.

    PubMed

    Shokri, N; Or, D

    2013-02-01

    Porous media containing sharp wettability discontinuities may occur in natural systems due to depositional processes, accumulation of organic layers or modification of soil wettability following intense forest fires all of which are known to significantly modify water flow and transport processes. We studied evaporation from sand columns containing hydraulically-interacting domains with sharp wettability contrasts. We employed neutron transmission technique to map liquid phase dynamics during evaporation, and conducted laboratory experiments to evaluate evaporative fluxes affected by interactions across wettability contrast. We explained the preferential drying front displacement in the hydrophobic domain and the spatial extent of capillary flow supporting the vaporization plane using a physically-based model. The model provides description of observed liquid phase patterns and dynamics observed in neutron radiography measurements and evaporative fluxes from laboratory experiments. Our results provide new insights into evaporation induced capillary exchange and preferential liquid phase distribution during evaporation from hydraulically interacting vertical porous domains with differing wettability properties and offer opportunities for design of selectively drying of porous media in natural and engineered systems. PMID:23123032

  19. Scaling of spontaneous imbibition data with wettability included.

    PubMed

    Li, Kewen

    2007-01-30

    Wettability is a dominant parameter governing spontaneous imbibition. However less attention has been paid to the effect of wettability on the scaling of spontaneous imbibition data. Actually few models can include wettability in scaling of spontaneous imbibition data. To this end, a scaling model has been developed for NAPL (oil)-saturated porous media with different wettability based on the fluid flow mechanisms in porous media. Relative permeability, capillary pressure, initial water saturation, and wettability are considered in the scaling model. Theoretically this scaling model is suitable for both cocurrent and countercurrent spontaneous imbibition. The experimental data of countercurrent spontaneous water imbibition at different wettability cannot be scaled using the frequently used scaling model but can be scaled satisfactorily using the scaling model developed in this study. An analytical solution to the relationship between recovery and imbibition time for linear spontaneous imbibition has also been derived in the case in which gravity is ignored. The analytical solution predicts a linear correlation between the recovery by spontaneous water imbibition and the square root of imbibition time, which has been verified against experimental data. PMID:17081652

  20. Scaling of spontaneous imbibition data with wettability included

    NASA Astrophysics Data System (ADS)

    Li, Kewen

    2007-01-01

    Wettability is a dominant parameter governing spontaneous imbibition. However less attention has been paid to the effect of wettability on the scaling of spontaneous imbibition data. Actually few models can include wettability in scaling of spontaneous imbibition data. To this end, a scaling model has been developed for NAPL (oil)-saturated porous media with different wettability based on the fluid flow mechanisms in porous media. Relative permeability, capillary pressure, initial water saturation, and wettability are considered in the scaling model. Theoretically this scaling model is suitable for both cocurrent and countercurrent spontaneous imbibition. The experimental data of countercurrent spontaneous water imbibition at different wettability cannot be scaled using the frequently used scaling model but can be scaled satisfactorily using the scaling model developed in this study. An analytical solution to the relationship between recovery and imbibition time for linear spontaneous imbibition has also been derived in the case in which gravity is ignored. The analytical solution predicts a linear correlation between the recovery by spontaneous water imbibition and the square root of imbibition time, which has been verified against experimental data.

  1. Hydraulic Property Alterations due to Wettability Induced Changes by Diesel Fuels

    NASA Astrophysics Data System (ADS)

    O'Carroll, Denis

    2013-04-01

    The remediation of non-aqueous phase liquid (NAPL) contaminated sites is impeded due to subsurface complexities, including wettability. Wettability quantifies which of two immiscible fluids preferentially coats a solid. At most contaminated sites water-wetting conditions are typically assumed despite mounting evidence that is not always the case. In this study, wettability was examined for two NAPL samples of contrasting origin: a fresh and a field sample. Wettability was assessed through (i) cyclical, 'cumulative elapsed contact time' intrinsic contact angle measurements, (ii) interface jar tests, and (iii) cyclical, pseudo-static capillary pressure-saturation curves. The work as a whole demonstrated that while the fresh diesel sample was consistently water-wet, the field diesel sample exhibited repeatable cycles of wettability reversal between water drainage and imbibition. And while wettability hysteresis increased with contact time for the field diesel, the occurrence of wettability reversal at each change of saturation direction was independent of contact time. Such behavior is not easily assessed by standard wettability indices. Moreover, it contrasts with the permanent wettability alteration observed for complex organics (e.g., coal tar) observed in most studies. It is hypothesized that the cyclical wettability reversal is related to cyclical changes in intermediate pore wettability due to sorption of surface active compounds (causing NAPL-wetting imbibition) and rupturing of the the soil grain water film (causing water-wet drainage). The wettability differences between the two NAPLs may be due to additives (i.e., a surfactant) in the original formulation and/or byproducts from subsurface weathering. These results support better characterization of site-specific wettability, improved model development and more realistic site conceptual models for improved remediation efforts.

  2. Differential radial capillary action of ligand assay for high-throughput detection of protein-metabolite interactions

    PubMed Central

    Roelofs, Kevin G.; Wang, Jingxin; Sintim, Herman O.; Lee, Vincent T.

    2011-01-01

    Interactions of proteins with low-molecular-weight ligands, such as metabolites, cofactors, and allosteric regulators, are important determinants of metabolism, gene regulation, and cellular homeostasis. Pharmaceuticals often target these interactions to interfere with regulatory pathways. We have developed a rapid, precise, and high-throughput method for quantitatively measuring protein-ligand interactions without the need to purify the protein when performed in cells with low background activity. This method, differential radial capillary action of ligand assay (DRaCALA), is based on the ability of dry nitrocellulose to separate the free ligand from bound proteinligand complexes. Nitrocellulose sequesters proteins and bound ligand at the site of application, whereas free ligand is mobilized by bulk movement of the solvent through capillary action. We show here that DRaCALA allows detection of specific interactions between three nucleotides and their cognate binding proteins. DRaCALA allows quantitative measurement of the dissociation constant and the dissociation rate. Furthermore, DRaCALA can detect the expression of a cyclic-di-GMP (cdiGMP)-binding protein in whole-cell lysates of Escherichia coli, demonstrating the power of the method to bypass the prerequisite for protein purification. We have used DRaCALA to investigate cdiGMP signaling in 54 bacterial species from 37 genera and 7 eukaryotic species. These studies revealed the presence of potential cdiGMP-binding proteins in 21 species of bacteria, including 4 unsequenced species. The ease of obtaining metabolite-protein interaction data using the DRaCALA assay will facilitate rapid identification of protein-metabolite and protein-pharmaceutical interactions in a systematic and comprehensive approach. PMID:21876132

  3. Reversing Glass Wettability

    NASA Technical Reports Server (NTRS)

    Frazier, D. O.; Smith, J. E., Jr.; Kaukler, W. F.

    1985-01-01

    Treatment reverses wettability of glassware: Liquids that normally wet glass no longer do, and those that do not wet glass are made to do so. Useful in research on container effects in nucleation and growth of secondary phase from solution. Treatment consists of spreading 3 percent (by weight) solution of silicone oil in hexane isomers over glass, drying in air, and curing at 300 degrees C in vacuum for one hour.

  4. Modeling Wettability Alteration using Chemical EOR Processes in Naturally Fractured Reservoirs

    SciTech Connect

    Mojdeh Delshad; Gary A. Pope; Kamy Sepehrnoori

    2007-09-30

    The objective of our search is to develop a mechanistic simulation tool by adapting UTCHEM to model the wettability alteration in both conventional and naturally fractured reservoirs. This will be a unique simulator that can model surfactant floods in naturally fractured reservoir with coupling of wettability effects on relative permeabilities, capillary pressure, and capillary desaturation curves. The capability of wettability alteration will help us and others to better understand and predict the oil recovery mechanisms as a function of wettability in naturally fractured reservoirs. The lack of a reliable simulator for wettability alteration means that either the concept that has already been proven to be effective in the laboratory scale may never be applied commercially to increase oil production or the process must be tested in the field by trial and error and at large expense in time and money. The objective of Task 1 is to perform a literature survey to compile published data on relative permeability, capillary pressure, dispersion, interfacial tension, and capillary desaturation curve as a function of wettability to aid in the development of petrophysical property models as a function of wettability. The new models and correlations will be tested against published data. The models will then be implemented in the compositional chemical flooding reservoir simulator, UTCHEM. The objective of Task 2 is to understand the mechanisms and develop a correlation for the degree of wettability alteration based on published data. The objective of Task 3 is to validate the models and implementation against published data and to perform 3-D field-scale simulations to evaluate the impact of uncertainties in the fracture and matrix properties on surfactant alkaline and hot water floods.

  5. Experimental investigations of the wettability of clays and shales

    NASA Astrophysics Data System (ADS)

    Borysenko, Artem; Clennell, Ben; Sedev, Rossen; Burgar, Iko; Ralston, John; Raven, Mark; Dewhurst, David; Liu, Keyu

    2009-07-01

    Wettability in argillaceous materials is poorly understood, yet it is critical to hydrocarbon recovery in clay-rich reservoirs and capillary seal capacity in both caprocks and fault gouges. The hydrophobic or hydrophilic nature of clay-bearing soils and sediments also controls to a large degree the movement of spilled nonaqueous phase liquids in the subsurface and the options available for remediation of these pollutants. In this paper the wettability of hydrocarbons contacting shales in their natural state and the tendencies for wettability alteration were examined. Water-wet, oil-wet, and mixed-wet shales from wells in Australia were investigated and were compared with simplified model shales (single and mixed minerals) artificially treated in crude oil. The intact natural shale samples (preserved with their original water content) were characterized petrophysically by dielectric spectroscopy and nuclear magnetic resonance, plus scanning electron, optical and fluorescence microscopy. Wettability alteration was studied using spontaneous imbibition, pigment extraction, and the sessile drop method for contact angle measurement. The mineralogy and chemical compositions of the shales were determined by standard methods. By studying pure minerals and natural shales in parallel, a correlation between the petrophysical properties, and wetting behavior was observed. These correlations may potentially be used to assess wettability in downhole measurements.

  6. Wettability Control on Fluid-Fluid Displacements in Patterned Microfluidics

    NASA Astrophysics Data System (ADS)

    Zhao, B.; Trojer, M.; Cueto-Felgueroso, L.; Juanes, R.

    2014-12-01

    Two-phase flow in porous media is important in many natural and industrial processes like geologic CO2 sequestration, enhanced oil recovery, and water infiltration in soil. While it is well known that the wetting properties of porous media can vary drastically depending on the type of media and the pore fluids, the effect of wettability on fluid displacement continues to challenge our microscopic and macroscopic descriptions. Here we study this problem experimentally, starting with the classic experiment of two-phase flow in a capillary tube. We image the shape of the meniscus and measure the associated capillary pressure for a wide range of capillary numbers. We confirm that wettability exerts a fundamental control on meniscus deformation, and synthesize new observations on the dependence of the dynamic capillary pressure on wetting properties (contact angle) and flow conditions (viscosity contrast and capillary number). We compare our experiments to a macroscopic phase-field model of two-phase flow. We use the insights gained from the capillary tube experiments to explore the viscous fingering instability in the Hele-Shaw geometry in the partial-wetting regime. A key difference between a Hele-Shaw cell and a porous medium is the existence of micro-structures (i.e. pores and pore throats). To investigate how these micro-structrues impact fluid-fluid displacement, we conduct experiments on a planar microfluidic device patterned with vertical posts. We track the evolution of the fluid-fluid interface and elucidate the impact of wetting on the cooperative nature of fluid displacement during pore invasion events. We use the insights gained from the capillary tube and patterned microfluidics experiments to elucidate the effect of wetting properties on viscous fingering and capillary fingering in a Hele-Shaw cell filled with glass beads, where we observe a contact-angle-dependent stabilizing behavior for the emerging flow instabilities, as the system transitions from drainage to imbibition.

  7. Wettability of graphene.

    PubMed

    Raj, Rishi; Maroo, Shalabh C; Wang, Evelyn N

    2013-04-10

    Graphene, an atomically thin two-dimensional material, has received significant attention due to its extraordinary electronic, optical, and mechanical properties. Studies focused on understanding the wettability of graphene for thermo-fluidic and surface-coating applications, however, have been sparse. Meanwhile, wettability results reported in literature via static contact angle measurement experiments have been contradictory and highlight the lack of clear understanding of the underlying physics that dictates wetting behavior. In this work, dynamic contact angle measurements and detailed graphene surface characterizations were performed to demonstrate that the defects present in CVD grown and transferred graphene coatings result in unusually high contact angle hysteresis (16-37) on these otherwise smooth surfaces. Hence, understanding the effect of the underlying substrate based on static contact angle measurements as reported in literature is insufficient. The advancing contact angle measurements on mono-, bi-, and trilayer graphene sheets on copper, thermally grown silica (SiO2), and glass substrates were observed to be independent of the number of layers of graphene and in good agreement with corresponding molecular dynamics simulations and theoretical calculations. Irrespective of the number of graphene layers, the advancing contact angle values were also in good agreement with the advancing contact angle on highly ordered pyrolytic graphite (HOPG), reaffirming the negligible effect of the underlying substrate. These results suggest that the advancing contact angle is a true representation of a graphene-coated surface while the receding contact angle is significantly influenced by intrinsic defects introduced during the growth and transfer processes. These observations, where the underlying substrates do not affect the wettability of graphene coatings, is shown to be due to the large interlayer spacing resulting from the loose interlamellar coupling between the graphene sheet and the underlying substrate. The fundamental insights on graphene-water interactions reported in this study is an important step towards developing graphene-assisted surface coatings for heat transfer and microfluidics devices. PMID:23458704

  8. Insulin transport across capillaries is rate limiting for insulin action in dogs.

    PubMed Central

    Yang, Y J; Hope, I D; Ader, M; Bergman, R N

    1989-01-01

    This study examined the relationship between transcapillary insulin transport and insulin action in vivo. During euglycemic clamps (n = 7) in normal conscious dogs we simultaneously measured plasma and thoracic duct lymph insulin and glucose utilization (Rd). Clamps consisted of an activation phase with constant insulin infusion (0.6 mU/kg per min) and a deactivation phase. [14C]Inulin was infused as a passively transported control substance. While [14C]inulin reached an equilibrium between plasma and lymph, steady-state (ss) plasma insulin was higher than lymph (P less than 0.05) and the ratio of 3:2 was maintained during basal, activation, and deactivation phases: 18 +/- 2 vs. 12 +/- 1, 51 +/- 2 vs. 32 +/- 1, and 18 +/- 3 vs. 13 +/- 1 microU/ml. In addition, it took longer for lymph insulin to reach ss than plasma insulin during activation and deactivation: 11 +/- 2 vs. 31 +/- 5 and 8 +/- 2 vs. 32 +/- 6 min (P less than 0.02). Rd increased from 2.6 +/- 0.1 to a ss of 6.6 +/- 0.4 mg/kg per min within 50 +/- 8 min. There was a remarkable similarity in the dynamics of insulin in lymph and Rd: the time to reach ss for Rd was not different from lymph insulin (P greater than 0.1), and the relative increases of the two measurements were similar, 164 +/- 45% and 189 +/- 29% (P greater than 0.05). While there was only a modest correlation (r = 0.78, P less than 0.01) between Rd and plasma insulin, the dynamic changes of lymph insulin and Rd showed a strong correlation (r = 0.95, P less than 0.01). The intimate relationship between lymph insulin and Rd suggests that the transcapillary insulin transport is primarily responsible for the delay in Rd. Thus, transcapillary transport may be rate limiting for insulin action, and if altered, it could be an important component of insulin resistance in obesity and diabetes mellitus. PMID:2681272

  9. Enhancing dropwise condensation through bioinspired wettability patterning.

    PubMed

    Ghosh, Aritra; Beaini, Sara; Zhang, Bong June; Ganguly, Ranjan; Megaridis, Constantine M

    2014-11-01

    Dropwise condensation (DWC) heat transfer depends strongly on the maximum diameter (Dmax) of condensate droplets departing from the condenser surface. This study presents a facile technique implemented to gain control of Dmax in DWC within vapor/air atmospheres. We demonstrate how this approach can enhance the corresponding heat transfer rate by harnessing the capillary forces in the removal of the condensate from the surface. We examine various hydrophilic-superhydrophilic patterns, which, respectively, sustain and combine DWC and filmwise condensation on the substrate. The material system uses laser-patterned masking and chemical etching to achieve the desired wettability contrast and does not employ any hydrophobizing agent. By applying alternating straight parallel strips of hydrophilic (contact angle ∼78°) mirror-finish aluminum and superhydrophilic regions (etched aluminum) on the condensing surface, we show that the average maximum droplet size on the less-wettable domains is nearly 42% of the width of the corresponding strips. An overall improvement in the condensate collection rate, up to 19% (as compared to the control case of DWC on mirror-finish aluminum) was achieved by using an interdigitated superhydrophilic track pattern (on the mirror-finish hydrophilic surface) inspired by the vein network of plant leaves. The bioinspired interdigitated pattern is found to outperform the straight hydrophilic-superhydrophilic pattern design, particularly under higher humidity conditions in the presence of noncondensable gases (NCG), a condition that is more challenging for maintaining sustained DWC. PMID:25295388

  10. Droplets Can Rebound toward Both Directions on Textured Surfaces with a Wettability Gradient.

    PubMed

    Zhang, Bo; Lei, Qing; Wang, Zuankai; Zhang, Xianren

    2016-01-12

    The impact of water droplets on superhydrophobic surfaces with a wettability gradient is studied using the lattice Boltzmann simulation. Droplets impacting such textured surfaces have been previously reported to rebound obliquely following the wettability gradient due to the unbalanced interfacial forces created by the heterogeneous architectures. Here we demonstrate that droplets can rebound toward both directions on textured surfaces with a wettability gradient. Our simulation results indicate that the rebound trajectory of droplets is determined by the competition between the lateral recoil of the liquid and the penetration and capillary emptying of the penetrated liquid from the textures in the vertical direction. When the time scale for the droplet penetration and capillary emptying process is smaller than the time for the lateral spreading, the droplet will rebound following the wettability gradient. By contrast, the droplet will display a bouncing against the wettability gradient direction because of the significant capillary penetration and emptying in the transverse direction. We believe that our study provides important insight for the design of micro/nanotextured surfaces for controlled droplet manipulation. PMID:26669260

  11. Evaluation of Reservoir Wettability and its Effect on Oil Recovery

    SciTech Connect

    Buckley, Jill S.

    1999-07-01

    The objective of this five-year project are: (1) to achieve improved understanding of the surface and interfacial properties of crude oils and their interactions with mineral surfaces, (2) to apply the results of surface studies to improve predictions of oil production from laboratory measurements, and (3) to use the results of this research to recommend ways to improve oil recovery by waterflooding. During the second year of this project we have tested the generality of the proposed mechanisms by which crude oil components can alter wetting. Using these mechanisms, we have begun a program of characterizing crude oils with respect to their wettability altering potential. Wettability assessment has been improved by replacing glass with mica as a standard surface material and crude oils have been used to alter wetting in simple square glass capillary tubes in which the subsequent imbibition of water can be followed visually.

  12. Distinctive Capillary Action by Micro-channels in Bone-like Templates can Enhance Recruitment of Cells for Restoration of Large Bony Defect.

    PubMed

    Oh, Daniel S; Koch, Alia; Eisig, Sidney; Kim, Sahng Gyoon; Kim, Yoon Hyuk; Kim, Do-Gyoon; Shim, Jae Hyuck

    2015-01-01

    Without an active, thriving cell population that is well-distributed and stably anchored to the inserted template, exceptional bone regeneration does not occur. With conventional templates, the absence of internal micro-channels results in the lack of cell infiltration, distribution, and inhabitance deep inside the templates. Hence, a highly porous and uniformly interconnected trabecular-bone-like template with micro-channels (biogenic microenvironment template; BMT) has been developed to address these obstacles. The novel BMT was created by innovative concepts (capillary action) and fabricated with a sponge-template coating technique. The BMT consists of several structural components: inter-connected primary-pores (300-400 µm) that mimic pores in trabecular bone, micro-channels (25-70 µm) within each trabecula, and nanopores (100-400 nm) on the surface to allow cells to anchor. Moreover, the BMT has been documented by mechanical test study to have similar mechanical strength properties to those of human trabecular bone (~3.8 MPa)12. The BMT exhibited high absorption, retention, and habitation of cells throughout the bridge-shaped (Π) templates (3 cm height and 4 cm length). The cells that were initially seeded into one end of the templates immediately mobilized to the other end (10 cm distance) by capillary action of the BMT on the cell media. After 4 hr, the cells homogenously occupied the entire BMT and exhibited normal cellular behavior. The capillary action accounted for the infiltration of the cells suspended in the media and the distribution (active migration) throughout the BMT. Having observed these capabilities of the BMT, we project that BMTs will absorb bone marrow cells, growth factors, and nutrients from the periphery under physiological conditions. The BMT may resolve current limitations via rapid infiltration, homogenous distribution and inhabitance of cells in large, volumetric templates to repair massive skeletal defects. PMID:26380953

  13. Distinctive Capillary Action by Micro-channels in Bone-like Templates can Enhance Recruitment of Cells for Restoration of Large Bony Defect

    PubMed Central

    Oh, Daniel S.; Koch, Alia; Eisig, Sidney; Kim, Sahng Gyoon; Kim, Yoon Hyuk; Kim, Do-Gyoon; Shim, Jae Hyuck

    2015-01-01

    Without an active, thriving cell population that is well-distributed and stably anchored to the inserted template, exceptional bone regeneration does not occur. With conventional templates, the absence of internal micro-channels results in the lack of cell infiltration, distribution, and inhabitance deep inside the templates. Hence, a highly porous and uniformly interconnected trabecular-bone-like template with micro-channels (biogenic microenvironment template; BMT) has been developed to address these obstacles. The novel BMT was created by innovative concepts (capillary action) and fabricated with a sponge-template coating technique. The BMT consists of several structural components: inter-connected primary-pores (300-400 µm) that mimic pores in trabecular bone, micro-channels (25-70 µm) within each trabecula, and nanopores (100-400 nm) on the surface to allow cells to anchor. Moreover, the BMT has been documented by mechanical test study to have similar mechanical strength properties to those of human trabecular bone (~3.8 MPa)12. The BMT exhibited high absorption, retention, and habitation of cells throughout the bridge-shaped (Π) templates (3 cm height and 4 cm length). The cells that were initially seeded into one end of the templates immediately mobilized to the other end (10 cm distance) by capillary action of the BMT on the cell media. After 4 hr, the cells homogenously occupied the entire BMT and exhibited normal cellular behavior. The capillary action accounted for the infiltration of the cells suspended in the media and the distribution (active migration) throughout the BMT. Having observed these capabilities of the BMT, we project that BMTs will absorb bone marrow cells, growth factors, and nutrients from the periphery under physiological conditions. The BMT may resolve current limitations via rapid infiltration, homogenous distribution and inhabitance of cells in large, volumetric templates to repair massive skeletal defects. PMID:26380953

  14. Antibacterial activity and mode of action of the Artemisia capillaris essential oil and its constituents against respiratory tract infection-causing pathogens.

    PubMed

    Yang, Chang; Hu, Dong-Hui; Feng, Yan

    2015-04-01

    Inhalation therapy using essential oils has been used to treat acute and chronic sinusitis and bronchitis. The aim of the present study was to determine the chemical composition of the essential oil of Artemisia capillaris, and evaluate the antibacterial effects of the essential oil and its main components, against common clinically relevant respiratory bacterial pathogens. Gas chromatography and gas chromatography?mass spectrometry revealed the presence of 25 chemical constituents, the main constituents being: ??pinene, ??pinene, limonene, 1,8?cineole, piperitone, ??caryophyllene and capillin. The antibacterial activities of the essential oil, and its major constituents, were evaluated against Streptococcus pyogenes, methicillin?resistant Staphylococcus aureus (MRSA), MRSA (clinical strain), methicillin?gentamicin resistant Staphylococcus aureus (MGRSA), Streptococcus pneumoniae, Klebsiella pneumoniae, Haemophilus influenzae and Escherichia coli. The essential oil and its constituents exhibited a broad spectrum and variable degree of antibacterial activity against the various strains. The essential oil was observed to be much more potent, as compared with any of its major chemical constituents, exhibiting low minimum inhibitory and bacteriocidal concentration values against all of the bacterial strains. The essential oil was most active against S. pyogenes, MRSA (clinical strain), S. pneumoniae, K. pneumoniae, H. influenzae and E. coli. Piperitone and capillin were the most potent growth inhibitors, among the major chemical constituents. Furthermore, the essential oil of A. capillaris induced significant and dose?dependent morphological changes in the S. aureus bacterial strain, killing >90% of the bacteria when administered at a higher dose; as determined by scanning electron microscopy. In addition, the essential oil induced a significant leakage of potassium and phosphate ions from the S. aureus bacterial cultures. These results indicate that the antibacterial action of A. capillaris essential oil may be mediated through the leakage of these two important ions. In conclusion, A. capillaris essential oil exhibits potent antibacterial activity by inducing morphological changes and leakage of ions in S. aureus bacterial cultures. PMID:25522803

  15. Metallic surfaces with special wettability

    NASA Astrophysics Data System (ADS)

    Liu, Kesong; Jiang, Lei

    2011-03-01

    Metals are important and irreplaceable engineered materials in our society. Nature is a school for scientists and engineers, which has long served as a source of inspiration for humans. Inspired by nature, a variety of metallic surfaces with special wettability have been fabricated in recent years through the combination of surface micro- and nanostructures and chemical composition. These metallic surfaces with special wettability exhibit important applications in anti-corrosion, microfluidic systems, oil-water separation, liquid transportation, and other fields. Recent achievements in the fabrication and application of metallic surfaces with special wettability are presented in this review. The research prospects and directions of this field are also briefly addressed. We hope this review will be beneficial to expand the practical applications of metals and offer some inspirations to the researchers in the fields of engineering, biomedicine, and materials science.

  16. Metallic surfaces with special wettability.

    PubMed

    Liu, Kesong; Jiang, Lei

    2011-03-01

    Metals are important and irreplaceable engineered materials in our society. Nature is a school for scientists and engineers, which has long served as a source of inspiration for humans. Inspired by nature, a variety of metallic surfaces with special wettability have been fabricated in recent years through the combination of surface micro- and nanostructures and chemical composition. These metallic surfaces with special wettability exhibit important applications in anti-corrosion, microfluidic systems, oil-water separation, liquid transportation, and other fields. Recent achievements in the fabrication and application of metallic surfaces with special wettability are presented in this review. The research prospects and directions of this field are also briefly addressed. We hope this review will be beneficial to expand the practical applications of metals and offer some inspirations to the researchers in the fields of engineering, biomedicine, and materials science. PMID:21212900

  17. Bioinspired surfaces with special wettability.

    PubMed

    Sun, Taolei; Feng, Lin; Gao, Xuefeng; Jiang, Lei

    2005-08-01

    Biomimetic research indicates that many phenomena regarding wettability in nature, such as the self-cleaning effect on a lotus leaf and cicada wing, the anisotropic dewetting behavior on a rice leaf, and striking superhydrophobic force provided by a water strider's leg, are all related to the unique micro- and nanostructures on the surfaces. It gives us much inspiration to realize special wettability on functional surfaces through the cooperation between the chemical composition and the surface micro- and nanostructures, which may bring great advantages in a wide variety of applications in daily life, industry, and agriculture. This Account reviews recent progress in these aspects. PMID:16104687

  18. Spontaneous imbibition in nanopores of different roughness and wettability.

    PubMed

    Stukan, Mikhail R; Ligneul, Patrice; Crawshaw, John P; Boek, Edo S

    2010-08-17

    The spontaneous imbibition of liquid in nanopores of different roughness is investigated using coarse grain molecular dynamics (MD) simulation. The numerical model is presented and the simplifying assumptions are discussed in detail. The molecular-kinetic theory introduced by Blake is used to describe the effect of dynamic contact angle on fluid imbibition. The capillary roughness is modeled using a random distribution of coarse grained particles forming the wall. The Lucas-Washburn equation is used as a reference for analyzing the imbibition curves obtained by simulation. Due to the statistical nature of MD processing, a comprehensive approach was made to average and smooth the data to accurately define a contact angle. The results are discussed in terms of effective hydrodynamic and static capillary radii and their difference as a function of roughness and wettability. PMID:20695576

  19. Microvalve actuation with wettability conversion through darkness/UV application

    NASA Astrophysics Data System (ADS)

    Gkhan Demir, Ali; Previtali, Barbara; Bestetti, Massimiliano

    2011-02-01

    In this work a new microvalve concept that employs wettability conversion through the alternate application of darkness and UV irradiation to switch between off and on states is studied. The control of pressure drop through capillary channels by wettability conversion is the exploited control mechanism to switch in between two states. As expressed in the Young-Laplace equation the pressure drop depends on the channel diameter and contact angle (CA) of a given fluid on the channel. In this application positive pressure values obtained in the hydrophobic region are used for blocking, and negative pressure values obtained at the hydrophilic region are used for releasing water through microchannels. In both regions the magnitude of the pressure drop can be increased by very small microchannel diameters and extreme values of the contact angle (i.e. 0 and 180). Laser microdrilling was chosen to generate the microchannels on commercially pure titanium sheets. The spatter produced by the laser drilling was removed by chemical etching, to improve the hole quality. Anodic oxidation was used for functionalizing the titanium microchannels with TiO2 layers that exhibit convertible wettability behaviour by alternate UV and darkness application. The actuation principle was demonstrated with a prototype microvalve produced.

  20. Quantitative evaluation of porous media wettability using NMR relaxometry.

    PubMed

    Fleury, M; Deflandre, F

    2003-01-01

    We propose a new method to determine wettability indices from NMR relaxometry. The new method uses the sensitivity of low field NMR relaxometry to the fluid distribution in oil-water saturated porous media. The model is based on the existence of a surface relaxivity for both oil and water, allowing the determination of the amount of surface wetted either by oil or by water. The proposed NMR wettability index requires the measurement of relaxation time distribution at four different saturation states. At the irreducible water saturation, we determine the dominant relaxation time of oil in the presence of a small amount of water, and at the oil residual saturation, we determine the dominant relaxation time of water in the presence of a small amount of oil. At 100% water and 100% oil saturation, we determine the surface relaxivity ratio. The interaction of oil with the surface is also evidenced by the comparison of the spin-lattice (T1) and spin-locking (T1rho) relaxation times. The new NMR index agrees with standard wettability measurements based on drainage-imbibition capillary pressure curves (USBM test) in the range [-0.3-1]. PMID:12850740

  1. Drop impact and wettability: From hydrophilic to superhydrophobic surfaces

    NASA Astrophysics Data System (ADS)

    Antonini, Carlo; Amirfazli, Alidad; Marengo, Marco

    2012-10-01

    Experiments to understand the effect of surface wettability on impact characteristics of water drops onto solid dry surfaces were conducted. Various surfaces were used to cover a wide range of contact angles (advancing contact angle from 48° to 166°, and contact angle hysteresis from 5° to 56°). Several different impact conditions were analyzed (12 impact velocities on 9 different surfaces, among which 2 were superhydrophobic). Results from impact tests with millimetric drops show that two different regimes can be identified: a moderate Weber number regime (30 < We < 200), in which wettability affects both drop maximum spreading and spreading characteristic time; and a high Weber number regime (We > 200), in which wettability effect is secondary, because capillary forces are overcome by inertial effects. In particular, results show the role of advancing contact angle and contact angle hysteresis as fundamental wetting parameters to allow understanding of different phases of drop spreading and beginning of recoiling. It is also shown that drop spreading on hydrophilic and superhydrophobic surfaces occurs with different time scales. Finally, if the surface is superhydrophobic, eventual impalement, i.e., transition from Cassie to Wenzel wetting state, which might occur in the vicinity of the drop impact area, does not influence drop maximum spreading.

  2. Femtosecond laser controlled wettability of solid surfaces.

    PubMed

    Yong, Jiale; Chen, Feng; Yang, Qing; Hou, Xun

    2015-12-14

    Femtosecond laser microfabrication is emerging as a hot tool for controlling the wettability of solid surfaces. This paper introduces four typical aspects of femtosecond laser induced special wettability: superhydrophobicity, underwater superoleophobicity, anisotropic wettability, and smart wettability. The static properties are characterized by the contact angle measurement, while the dynamic features are investigated by the sliding behavior of a liquid droplet. Using different materials and machining methods results in different rough microstructures, patterns, and even chemistry on the solid substrates. So, various beautiful wettabilities can be realized because wettability is mainly dependent on the surface topography and chemical composition. The distinctions of the underlying formation mechanism of these wettabilities are also described in detail. PMID:26415826

  3. Water wettability in nanoconfined environment

    NASA Astrophysics Data System (ADS)

    Zhou, YaHong; Guo, Wei; Jiang, Lei

    2014-05-01

    Water confined in nanoscale space behaves quite differently from that in the bulk. For example, in biological aquaporins and in carbon nanotubes, the traversing water molecules form a single file configuration. Water would stay in vapor state in extremely hydrophobic narrow nanopores owing to the physicochemical interactions between the water molecules and the surface of the nanopore. A spontaneous wet-dry transition has been identified in both biological and artificial nanopores. The nanopore is either fulfilled with liquid water or completely empty. Based on this mechanism, the wetting and dewetting processes inside nanopores have been further developed into highly efficient nanofluidic gates that can be switched by external stimuli, such as light irradiation, electric potential, temperature, and mechanical pressure. This review briefly covers the recent progress in the special wettability in nanoconfined environment, water transportation through biological or artificial nanochannels, as well as the smart nanofluidic gating system controlled by the water wettability.

  4. New concept for coal wettability evaluation and modulation. Technical progress report, April 1, 1993--June 30, 1993

    SciTech Connect

    Hu, W.

    1993-09-01

    This project is concerned with the new concept for coal surface wettability evaluation and modulation. The objective of the work is to study the fundamental surface chemistry features about the evaluation of the surface wettability of coal and pyrite and establish a new separation strategy which could contribute to the advanced coal-cleaning for premium fuel application. In the past quarter report, the capillary rise test results of three coal and mineral pyrite samples in distilled water, kerosene, and salt solution indicated that there are good agreements between the experimental observations and theoretical assumption. In this quarter, the further capillary rise tests were conducted for coal, pyrite and coal pyrite in distilled water, kerosene and benzene. The test results shown that surface wettability of coal, mineral pyrite, and coal pyrite have good correlation with the theoretical predictions.

  5. New concept for coal wettability evaluation and modulation. Technical progress report, October 1, 1993--December 31, 1993

    SciTech Connect

    Hu, Weibai

    1993-12-31

    This project is concerned concept for coal surface wettability evaluation and modulation. The objective of the work are to study the fundamental surface chemistry feature about the evaluation of the surface of coal, pyrite and coal pyrite, and also establish a new separation strategy which could contribute to the advanced coal cleaning for premium fuel application. In this quarter, the capillary rise of three coals, colorado mineral pyrite, and coal pyrite in butanol, pentanol, and butyl ether have been tested. The test results shown that the kinetic wettability of the five samples in the alcohol homolog are dependent on the carbon chain length, as the length of the carbon chain is shorter, the surface wettability is the better. Another test results shown that the kinetic wettability of coals are better than mineral pyrite and coal pyrite in the butyl ether.

  6. Electron-induced wettability modification

    SciTech Connect

    Aronov, Daniel; Molotskii, Michel; Rosenman, Gil

    2007-07-15

    The pioneering works by Lippmann [Ann. Chim. Phys. 5, 494 (1875)] and Frumkin [Actual. Sci. Ind. 373, 5 (1936)] reported on electrowetting phenomenon. It was shown that electric potential, applied to an interface between a conducting liquid droplet and solid surface, strengthened the wetting effect. Here, we describe pronounced decrease of wettability induced by a low-energy electron irradiation. We observe this effect in many materials of different origins. The proposed theory of this phenomenon explains the found growth of the hydrophobicity under an electron irradiation by decreasing solid/liquid and solid/vapor interfacial free energies, when reduction of the latter is always higher. This theory considers the droplet shape dependence on the incident electron charge density and energy of the incident electrons, as well as on the liquid and solid origins. The results of calculations are in a good agreement with the experimental data obtained for water droplet on amorphous silicon dioxide. The effect of the decrease of the wettability, induced by an electron irradiation at low incident charge, is completely reversible after subjection of the electron-irradiated material to ultraviolet illumination, which restores its initial wettability state.

  7. A pore-level scenario for the development of mixed-wettability in oil reservoirs

    SciTech Connect

    Kovscek, A.R.; Wong, H.; Radke, C.J.

    1992-09-01

    Understanding the role of thin films in porous media is vital if wettability is to be elucidated at the pore level. The type and thickness of films coating pore walls determines reservoir wettability and whether or not reservoir rock can be altered from its initial state of wettability. Pore shape, especially pore wall curvature, is an important factor in determining wetting-film thicknesses. Yet, pore shape and the physics of thin wetting films are generally neglected in models of flow in porous rocks. This paper incorporates thin-film forces into a collection of star-shaped capillary tubes model to describe the geological development of mixed-wettability in reservoir rock. Here, mixed-wettability refers to continuous and distinct oil and water-wetting surfaces coexisting in the porous medium. The proposed model emphasizes the remarkable role of thin films. New pore-level fluid configurations arise that are quite unexpected. For example, efficient water displacement of oil (i.e, low residual oil saturation) characteristic of mixed-wettability porous media is ascribed to interconnected oil lenses or rivulets which bridge the walls adjacent to a pore corner. Predicted residual oil saturations are approximately 35 % less in mixed-wet rock compared to completely water-wet rock. Calculated capillary pressure curves mimic those of mixed-wet porous media in the primary drainage of water, imbibition of water, and secondary drainage modes. Amott-Harvey indices range from {minus}0.18 to 0.36 also in good agreement with experimental values. (Morrow et al, 1986; Judhunandan and Morrow, 1991).

  8. Mechanistic study of wettability alteration using surfactants with applications in naturally fractured reservoirs.

    PubMed

    Salehi, Mehdi; Johnson, Stephen J; Liang, Jenn-Tai

    2008-12-16

    In naturally fractured reservoirs, oil recovery from waterflooding relies on the spontaneous imbibition of water to expel oil from the matrix into the fracture system. The spontaneous imbibition process is most efficient in strongly water-wet rock where the capillary driving force is strong. In oil- or mixed-wet fractured carbonate reservoirs, however, the capillary driving force for the spontaneous imbibition process is weak, and therefore the waterflooding oil recoveries are low. The recovery efficiency can be improved by dissolving low concentrations of surfactants in the injected water to alter the wettability of the reservoir rock to a more water-wet state. This wettability alteration accelerates the spontaneous imbibition of water into matrix blocks, thereby increasing the oil recovery during waterflooding. Several mechanisms have been proposed to explain the wettability alteration by surfactants, but none have been verified experimentally. Understanding of the mechanisms behind wettability alteration could help to improve the performance of the process and aid in identification of alternative surfactants for use in field applications. Results from this study revealed that ion-pair formation and adsorption of surfactant molecules through interactions with the adsorbed crude oil components on the rock surface are the two main mechanisms responsible for the wettability alteration. Previous researchers observed that, for a given rock type, the effectiveness of wettability alteration is highly dependent upon the ionic nature of the surfactant involved. Our experimental results demonstrated that ion-pair formation between the charged head groups of surfactant molecules and the adsorbed crude oil components on rock surface was more effective in changing the rock wettability toward a more water-wet state than the adsorption of surfactant molecules as a monolayer on the rock surface through hydrophobic interaction with the adsorbed crude oil components. By comparing two anionic surfactants with different charge densities, we propose that wettability alteration processes might be improved through the use of dimeric surfactants, which have two charged head groups and two hydrophobic tails. Gemini surfactants where the molecules are joined at the head end are likely to be effective when ion-pair formation is the wettability alteration mechanism, and bolaform surfactants, in which molecules are joined by the hydrophobic tails, should be more effective in the case of surfactant monolayer adsorption. PMID:19053658

  9. Diagenetic and compositional controls of wettability in siliceous sedimentary rocks, Monterey Formation, California

    NASA Astrophysics Data System (ADS)

    Hill, Kristina M.

    Modified imbibition tests were performed on 69 subsurface samples from Monterey Formation reservoirs in the San Joaquin Valley to measure wettability variation as a result of composition and silica phase change. Contact angle tests were also performed on 6 chert samples from outcrop and 3 nearly pure mineral samples. Understanding wettability is important because it is a key factor in reservoir fluid distribution and movement, and its significance rises as porosity and permeability decrease and fluid interactions with reservoir grain surface area increase. Although the low permeability siliceous reservoirs of the Monterey Formation are economically important and prolific, a greater understanding of factors that alter their wettability will help better develop them. Imbibition results revealed a strong trend of decreased wettability to oil with increased detrital content in opal-CT phase samples. Opal-A phase samples exhibited less wettability to oil than both opal-CT and quartz phase samples of similar detrital content. Subsurface reservoir samples from 3 oil fields were crushed to eliminate the effect of capillary pressure and cleansed of hydrocarbons to eliminate wettability alterations by asphaltene, then pressed into discs of controlled density. Powder discs were tested for wettability by dispensing a controlled volume of water and motor oil onto the surface and measuring the time required for each fluid to imbibe into the sample. The syringe and software of a CAM101 tensiometer were used to control the amount of fluid dispensed onto each sample, and imbibition completion times were determined by high-speed photography for water drops; oil drop imbibition was significantly slower and imbibition was timed and determined visually. Contact angle of water and oil drops on polished chert and mineral sample surfaces was determined by image analysis and the Young-Laplace equation. Oil imbibition was significantly slower with increased detrital composition and faster with increased silica content in opal-CT and quartz phase samples, implying decreased wettability to oil with increased detrital (clay) content. However, contact angle tests showed that opal-CT is more wetting to oil with increased detritus and results for oil on quartz-phase samples were inconsistent between different proxies for detritus over their very small compositional range. Water contact angle trends also showed inconsistent wetting trends compared to imbibition tests. We believe this is because the small range in bulk detrital composition between the "pure" samples used in contact angle tests was close to analytical error and because small-scale spatial compositional variability may be significant enough to effect wettability. These experiments show that compositional variables significantly affect wettability, outweighing the effect of silica phase.

  10. Wettability effects on droplet coalescence

    NASA Astrophysics Data System (ADS)

    Graham, Percival; de Pauw, Dennis; Dolatabadi, Ali

    2012-11-01

    Droplet impingement has been studied since 1895, with the works of A.M. Worthington. Throughout the past century, a variety of interesting phenomena have been uncovered. These include the bouncing of droplets off of each other or liquid pools, intricate droplet splashing mechanics, and droplets bouncing off of superhydrophobic surfaces; to name a few. In addition to intricate phenomena, droplet dynamics are relevant to many engineering applications, such as painting, spray coating ink-jet printing, and ice accumulation. These fields all involve interactions between droplets; therefore, studying droplet coalescence would benefit them greatly. The works presented include the coalescence of droplets with different impact conditions, various offsets, and at different wettabilities. Surface wettabilities studied are hydrophilic, hydrophobic and superhydrophobic. Fascinating phenomena observed include, bouncing of the impinging droplet off of the sessile droplet, sliding of the impinging droplet along the sessile droplet, and induced detachment on the sessile droplet on superhydrophobic surfaces. In order to capture the maximum spreading of the merged droplets, models related to coalescence of droplets in air and maximum spreading of a single droplet are combined to yield a new model to predict the maximum spreading of head-on droplet impact. Based on the free surface, and accuracy of the analytical model, droplet impact could be viewed as a mix of droplet coalescence in a gaseous media and droplet impact on a dry surface. Funding from NSERC.

  11. Capillary-Driven Flow in Liquid Filaments Connecting Orthogonal Channels

    NASA Technical Reports Server (NTRS)

    Allen, Jeffrey S.

    2005-01-01

    Capillary phenomena plays an important role in the management of product water in PEM fuel cells because of the length scales associated with the porous layers and the gas flow channels. The distribution of liquid water within the network of gas flow channels can be dramatically altered by capillary flow. We experimentally demonstrate the rapid movement of significant volumes of liquid via capillarity through thin liquid films which connect orthogonal channels. The microfluidic experiments discussed provide a good benchmark against which the proper modeling of capillarity by computational models may be tested. The effect of surface wettability, as expressed through the contact angle, on capillary flow will also be discussed.

  12. Effects of surface wettability and liquid viscosity on the dynamic wetting of individual drops.

    PubMed

    Chen, Longquan; Bonaccurso, Elmar

    2014-08-01

    In this paper, we experimentally investigated the dynamic spreading of liquid drops on solid surfaces. Drop of glycerol water mixtures and pure water that have comparable surface tensions (62.3-72.8 mN/m) but different viscosities (1.0-60.1 cP) were used. The size of the drops was 0.5-1.2 mm. Solid surfaces with different lyophilic and lyophobic coatings (equilibrium contact angle ?(eq) of 0-112) were used to study the effect of surface wettability. We show that surface wettability and liquid viscosity influence wetting dynamics and affect either the coefficient or the exponent of the power law that describes the growth of the wetting radius. In the early inertial wetting regime, the coefficient of the wetting power law increases with surface wettability but decreases with liquid viscosity. In contrast, the exponent of the power law does only depend on surface wettability as also reported in literature. It was further found that surface wettability does not affect the duration of inertial wetting, whereas the viscosity of the liquid does. For low viscosity liquids, the duration of inertial wetting corresponds to the time of capillary wave propagation, which can be determined by Lamb's drop oscillation model for inviscid liquids. For relatively high viscosity liquids, the inertial wetting time increases with liquid viscosity, which may due to the viscous damping of the surface capillary waves. Furthermore, we observed a viscous wetting regime only on surfaces with an equilibrium contact angle ?(eq) smaller than a critical angle ?(c) depending on viscosity. A scaling analysis based on Navier-Stokes equations is presented at the end, and the predicted ?(c) matches with experimental observations without any additional fitting parameters. PMID:25215736

  13. Capillary Hemangioma

    MedlinePLUS

    ... between 12 and 15 months of age. Most regress nearly completely by 5 or 6 years of ... away? Capillary hemangiomas typically take several years to regress. The involved skin may retain a red color ...

  14. Capillary electrophoresis.

    PubMed

    Gordon, M J; Huang, X; Pentoney, S L; Zare, R N

    1988-10-14

    Electrophoretic separations carried out in capillary tubes offer the possibilities of rapid and automated analyses of small volumes of complex mixtures with unprecedented resolution and sensitivity. Some emerging developments of this new instrumentation are reviewed. PMID:17787651

  15. Wettability of Aluminum on Alumina

    NASA Astrophysics Data System (ADS)

    Bao, Sarina; Tang, Kai; Kvithyld, Anne; Tangstad, Merete; Engh, Thorvald Abel

    2011-12-01

    The wettability of molten aluminum on solid alumina substrate has been investigated by the sessile drop technique in a 10-8 bar vacuum or under argon atmosphere in the temperature range from 1273 K to 1673 K (1000 C to 1400 C). It is shown that the reduction of oxide skin on molten aluminum is slow under normal pressures even with ultralow oxygen potential, but it is enhanced in high vacuum. To describe the wetting behavior of the Al-Al2O3 system at lower temperatures, a semiempirical calculation was employed. The calculated contact angle at 973 K (700 C) is approximately 97 deg, which indicates that aluminum does not wet alumina at aluminum casting temperatures. Thus, a priming height is required for aluminum to infiltrate a filter. Wetting in the Al-Al2O3 system increases with temperature.

  16. New concept for coal wettability evaluation and modulation. Technical progress report, July 1, 1993--September 30, 1993

    SciTech Connect

    Hu, Weibai

    1993-12-01

    The ratio of kinetics of capillary rise test between different media is a measure of relative wettability. From table 1, 2 and 3, the Hu`s evaluation of wettability of five samples in the methanol, ethanol and propanol are shown that the kinetic wettability is dependent on the carbon homologous series of alcohol, as shorter the carbon chain of the alcohol, the better surface wettability. The Hu`s evaluation of wettability of H{sub H2O}/H{sub methanol}, H{sub H2O}/H{sub ethanol}, and H{sub H2O}/H{sub propanol} for five samples are listed respectively in table 4, 5 and 6. It indicates that in the water/methanol, water/ethanol, and water/propanol system, Upper Freeport Coal is very little hydrophilicity, or better floatability than Coal Pyrite, it also can be seen that in these system, Pittsburgh No.8 Coal have a little hydrophilicity, or better floatability than Coal pyrite, it would mean that if Methanol, Ethanol, and Propanol are used as flotation collector, coal will be selectively separated from coal pyrite. This has been verified by our investigation elsewhere. The Hu`s evaluation of wettability of H{sub methanol}/H{sub kerosene} for five samples are listed in table 7. It is very interesting to note that the five samples have more methanol-philicity than kerosene. This is very useful for flotation reagents evaluation and selection in practice. The Hu`s evaluation of wettability of H{sub ethanol}/H{sub kerosene} for five samples are listed in table 8. It is indicated that ethanol also can be used as flotation collector. The Hu`s evaluation of wettability H{sub propanol}/H{sub kerosene} for five samples are listed in table 9. It shows that the five samples have lower propanol-philicity than kerosene.

  17. Influence of wettability on constitutive relations and its role in upscaling

    SciTech Connect

    Soll, W.E.; Gray, W.G.; Tompson, A.F.B.

    1998-07-01

    The lattice Boltzmann (LB) method is applied to simulating multifluid flow in porous media at sub-pore resolution to determine constitutive behaviors. The authors address the importance of the LB technique for identifying process based constitutive relationships, and demonstrate its application through analysis of the influence of wettability on interfacial areas and constitutive relationships. Porous media surface wettability is varied from uniformly strongly wetted by the resident fluid through strongly wetted by the displacing fluid. Spatially variable wettability is also demonstrated. Primary imbibition and drainage displacements are run, and interfacial areas (IFA) as a function of time are determined and compared. Results indicate that wettability is an important factor in displacement behavior and resulting interfacial area. Primary imbibition in a strongly wet material under capillary dominated flows produces film flow, resulting in high IFAs that decrease with increasing saturation and viscous forces. Primary drainage produces initially high IFA that decreases slightly with increasing saturation or pressure drop. Surfaces with spatially variable wetting can have a strong influence on resulting fluid distributions and fluid flow.

  18. A study of metal-ceramic wettability in SiC-Al using dynamic melt infiltration of SiC

    NASA Technical Reports Server (NTRS)

    Asthana, R.; Rohatgi, P. K.

    1993-01-01

    Pressure-assisted infiltration with a 2014 Al alloy of plain and Cu-coated single crystal platelets of alpha silicon carbide was used to study particulate wettability under dynamic conditions relevant to pressure casting of metal-matrix composites. The total penetration length of infiltrant metal in porous compacts was measured at the conclusion of solidification as a function of pressure, infiltration time, and SiC size for both plain and Cu-coated SiC. The experimental data were analyzed to obtain a threshold pressure for the effect of melt intrusion through SiC compacts. The threshold pressure was taken either directly as a measure of wettability or converted to an effective wetting angle using the Young-Laplace capillary equation. Cu coating resulted in partial but beneficial improvements in wettability as a result of its dissolution in the melt, compared to uncoated SiC.

  19. Asymmetric Wettability Directs Leidenfrost Droplets

    SciTech Connect

    Agapov, Rebecca L; Boreyko, Jonathan B; Briggs, Dayrl P; Srijanto, Bernadeta R; Retterer, Scott T; Collier, Pat; Lavrik, Nickolay V

    2014-01-01

    Leidenfrost phenomena on nano- and microstructured surfaces are of great importance for increasing control over heat transfer in high power density systems utilizing boiling phenomena. They also provide an elegant means to direct droplet motion in a variety of recently emerging fluidic systems. Here, we report the fabrication and characterization of tilted nanopillar arrays (TNPAs) that exhibit directional Leidenfrost water droplets under dynamic conditions, namely on impact with Weber numbers 40 at T 325 C. The batch fabrication of the TNPAs was achieved by glancing-angle anisotropic reactive ion etching of a thermally dewet platinum mask, with mean pillar diameters of 100 nm and heights of 200-500 nm. In contrast to previously implemented macro- and microscopic Leidenfrost ratchets, our TNPAs induce no preferential directional movement of Leidenfrost droplets under conditions approaching steady-state film boiling, suggesting that the observed droplet directionality is not a result of asymmetric vapor flow. Using high-speed imaging, phase diagrams were constructed for the boiling behavior upon impact for droplets falling onto TNPAs, straight nanopillar arrays, and smooth silicon surfaces. The asymmetric impact and directional trajectory of droplets was exclusive to the TNPAs for impacts corresponding to the transition boiling regime, revealing that asymmetric wettability upon impact is the mechanism for the droplet directionality.

  20. Wettability modification of rock cores by fluorinated copolymer emulsion for the enhancement of gas and oil recovery

    NASA Astrophysics Data System (ADS)

    Feng, Chunyan; Kong, Ying; Jiang, Guancheng; Yang, Jinrong; Pu, Chunsheng; Zhang, Yuzhong

    2012-07-01

    The fluorine-containing acrylate copolymer emulsion was prepared with butyl acrylate, methacrylic acid and 1H, 1H, 2H, 2H-perfluorooctyl acrylate as monomers. Moreover, the structure of the copolymer was verified by Fourier transform infrared (FTIR), nuclear magnetic resonance (1H NMR and 19F NMR) and X-ray photoelectron spectroscopy (XPS) analyses. The results showed that all the monomers had been copolymerized and the presence of fluorine moieties. The contact angle (CA) analyses, capillary rise and imbibition spontaneous tests were used to estimate the influence of the copolymer emulsion on the wettability of gas reservoirs. It was observed that the rock surface was of large contact angles of water, oilfield sewage, hexadecane and crude oil after treatment with the emulsion. The capillary rise results indicated that the contact angles of water/air and oil/air systems increased from 60 and 32 to 121 and 80, respectively, due to the emulsion treatment. Similarly, because of wettability alteration by the fluoropolymer, the imbibition of water and oil in rock core decreased significantly. Experimental results demonstrated that the copolymer emulsion can alter the wettability of porous media from strong liquid-wetting to gas-wetting. This work provides a cost-effective method to prepare the fluoropolymer which can increase gas deliverability by altering the wettability of gas-condensate reservoirs and mitigating the water block effect.

  1. Capillary filling dynamics of water in nanopores

    NASA Astrophysics Data System (ADS)

    Bakli, Chirodeep; Chakraborty, Suman

    2012-10-01

    We portray a universal description of dynamic slip-stick behavior of water flowing through nanoscale pores. Based on fundamental molecular transport considerations, we derive a generalized constitutive model for describing resistive forces acting on the water column in a capillary that is being dynamically filled, as a combined function of the meniscus height, surface wettability, and roughness. This effectively acts like a unique signature of nanopore imbibition characteristics of water, which, when substituted in a simple one-dimensional force balance model agrees quantitatively with results from molecular dynamics simulations for a general class of problems, without necessitating the employment of any artificially tunable fitting parameters.

  2. Wettability alteration by trimeric cationic surfactant at water-wet/oil-wet mica mineral surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, Rui; Qin, Ni; Peng, Lin; Tang, Ke; Ye, Zhongbin

    2012-08-01

    The wettability of oil reservoir rock affects the efficiency of the oil recovery process by reducing the capillary force. Methyldodecylbis [2-(dimethyldodecylammonio) ethyl] ammonium tribromide is a trimeric cationic surfactant that contains three dodecyl chains and three quaternary ammonium head groups connected by divinyl groups. The surfactant was synthesized, purified and used as a new wetting alteration agent. This paper focuses on the ability of this trimeric cationic surfactant to alter the wettability of water-wet and oil-wet mica mineral surfaces. The contact angle data of the solid-liquid interface in oil/water/solid three-phase system show that the trimeric cationic surfactant, when compared with single- and double-chain cationic surfactant, is a more effective wetting agent for water-wet and oil-wet mica surfaces at lower concentration. Measurements by atomic force microscopy (AFM) show that the surfactant molecules have formed a monolayer to reverse the wetting properties. On the water-wet surface, the surface is suffused with negative charge, which could attract the cationic head of surfactant, and leave the hydrophobic tails exposed. In contrast, on the oil-wet surface, the hydrophobic tails were attracted by hydrophobic interactions to the oil film between the surfactant and the crude oil. The hydrophilic heads were left outside to form a hydrophilic layer, which could explain the wettable to hydrophilic trend. Alteration to the degree of wettability is mainly dependent on the adsorption areas of the surfactant. The data show that the ability of the trimeric cationic surfactant affect the wettability is independent of surface tension.

  3. Nanofluid surface wettability through asymptotic contact angle.

    PubMed

    Vafaei, Saeid; Wen, Dongsheng; Borca-Tasciuc, Theodorian

    2011-03-15

    This investigation introduces the asymptotic contact angle as a criterion to quantify the surface wettability of nanofluids and determines the variation of solid surface tensions with nanofluid concentration and nanoparticle size. The asymptotic contact angle, which is only a function of gas-liquid-solid physical properties, is independent of droplet size for ideal surfaces and can be obtained by equating the normal component of interfacial force on an axisymmetric droplet to that of a spherical droplet. The technique is illustrated for a series of bismuth telluride nanofluids where the variation of surface wettability is measured and evaluated by asymptotic contact angles as a function of nanoparticle size, concentration, and substrate material. It is found that the variation of nanofluid concentration, nanoparticle size, and substrate modifies both the gas-liquid and solid surface tensions, which consequently affects the force balance at the triple line, the contact angle, and surface wettability. PMID:21338112

  4. Dynamics of capillary infiltration of liquids into a highly aligned multi-walled carbon nanotube film

    PubMed Central

    Walczak, Krzysztof Z; Koziol, Krzysztof K K

    2011-01-01

    Summary The physical compatibility of a highly aligned carbon nanotube (HACNT) film with liquids was established using a fast and convenient experimental protocol. Two parameters were found to be decisive for the infiltration process. For a given density of nanotube packing, the thermodynamics of the infiltration process (wettability) were described by the contact angle between the nanotube wall and a liquid meniscus (?). Once the wettability criterion (? < 90) was met, the HACNT film (of free volume equal to 91%) was penetrated gradually by the liquid in a rate that can be linearly correlated to dynamic viscosity of the liquid (?). The experimental results follow the classical theory of capillarity for a steady process (LucasWashburn law), where the nanoscale capillary force, here supported by gravity, is compensated by viscous drag. This most general theory of capillarity can be applied in a prediction of both wettability of HACNT films and the dynamics of capillary rise in the intertube space in various technological applications. PMID:21977444

  5. 21 CFR 864.6150 - Capillary blood collection tube.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Capillary blood collection tube. 864.6150 Section... blood collection tube. (a) Identification. A capillary blood collection tube is a plain or heparinized glass tube of very small diameter used to collect blood by capillary action. (b) Classification. Class...

  6. 21 CFR 864.6150 - Capillary blood collection tube.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Capillary blood collection tube. 864.6150 Section... blood collection tube. (a) Identification. A capillary blood collection tube is a plain or heparinized glass tube of very small diameter used to collect blood by capillary action. (b) Classification. Class...

  7. 21 CFR 864.6150 - Capillary blood collection tube.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Capillary blood collection tube. 864.6150 Section... blood collection tube. (a) Identification. A capillary blood collection tube is a plain or heparinized glass tube of very small diameter used to collect blood by capillary action. (b) Classification. Class...

  8. 21 CFR 864.6150 - Capillary blood collection tube.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Capillary blood collection tube. 864.6150 Section... blood collection tube. (a) Identification. A capillary blood collection tube is a plain or heparinized glass tube of very small diameter used to collect blood by capillary action. (b) Classification. Class...

  9. Polymeric surfaces exhibiting photocatalytic activity and controlled anisotropic wettability

    NASA Astrophysics Data System (ADS)

    Anastasiadis, Spiros H.; Frysali, Melani A.; Papoutsakis, Lampros; Kenanakis, George; Stratakis, Emmanuel; Vamvakaki, Maria; Mountrichas, Grigoris; Pispas, Stergios

    2015-03-01

    In this work we focus on surfaces, which exhibit controlled, switchable wettability in response to one or more external stimuli as well as photocatalytic activity. For this we are inspired from nature to produce surfaces with a dual-scale hierarchical roughness and combine them with the appropriate inorganic and/or polymer coating. The combination of the hierarchical surface with a ZnO coating and a pH- or temperature-responsive polymer results in efficient photo-active properties as well as reversible superhydrophobic / superhydrophilic surfaces. Furthermore, we fabricate surfaces with unidirectional wettability variation. Overall, such complex surfaces require advanced design, combining hierarchically structured surfaces with suitable polymeric materials. Acknowledgment: This research was partially supported by the European Union (European Social Fund, ESF) and Greek national funds through the ``ARISTEIA II'' Action (SMART-SURF) of the Operational Programme ``Education and Lifelong Learning,'' NSRF 2007-2013, via the General Secretariat for Research & Technology, Ministry of Education and Religious Affairs, Greece.

  10. Wettability inversion induced by weak electron irradiation

    SciTech Connect

    Aronov, Daniel; Molotskii, Michel

    2008-12-01

    We investigate a wettability modification of ultrathin dielectric films induced by an electron irradiation. The effect of wettability inversion, transition from hydrophobic to hydrophilic state, is predicted for low irradiation doses. It is supposed that the inversion is caused by a change in the basic mechanism of the influence of an electron irradiation on the interface free energy. For high irradiation doses, the effect of the decrease in wettability under electron irradiation is caused by the interactions of an excess charge in the film with its image charges. At low doses, the mechanism is referred to the interaction of surface charges, which function as hydrophilic adsorption centers, with water molecules. The predicted effect of the wettability inversion has been experimentally verified with electron irradiation of silicon dioxide ultrathin films. A dramatic reduction in water drop surface tension on the liquid/vapor interface has been observed. Such reduction is explained by drop charging as a result of carriers tunneling from semiconductor through ultrathin oxide layer.

  11. CO2 wettability of seal and reservoir rocks and the implications for carbon geo-sequestration

    NASA Astrophysics Data System (ADS)

    Iglauer, Stefan; Pentland, C. H.; Busch, A.

    2015-01-01

    We review the literature data published on the topic of CO2 wettability of storage and seal rocks. We first introduce the concept of wettability and explain why it is important in the context of carbon geo-sequestration (CGS) projects, and review how it is measured. This is done to raise awareness of this parameter in the CGS community, which, as we show later on in this text, may have a dramatic impact on structural and residual trapping of CO2. These two trapping mechanisms would be severely and negatively affected in case of CO2-wet storage and/or seal rock. Overall, at the current state of the art, a substantial amount of work has been completed, and we find that: Sandstone and limestone, plus pure minerals such as quartz, calcite, feldspar, and mica are strongly water wet in a CO2-water system. Oil-wet limestone, oil-wet quartz, or coal is intermediate wet or CO2 wet in a CO2-water system. The contact angle alone is insufficient for predicting capillary pressures in reservoir or seal rocks. The current contact angle data have a large uncertainty. Solid theoretical understanding on a molecular level of rock-CO2-brine interactions is currently limited. In an ideal scenario, all seal and storage rocks in CGS formations are tested for their CO2 wettability. Achieving representative subsurface conditions (especially in terms of the rock surface) in the laboratory is of key importance but also very challenging.

  12. Capillary rise in nanotubes coated with polymer brushes.

    PubMed

    Dimitrov, D I; Milchev, A; Binder, K

    2009-04-01

    The spontaneous rise of a fluid in a brush-coated nanocapillary is studied by molecular dynamics simulation of a coarse-grained model. The cases of changing wettability of both the capillary walls and the brush were examined. We also investigated the impact of polymer chain length on the transport of fluid along the nanotube. We found that capillary filling takes place in both lyophilic and lyophobic tubes, provided that the polymer brush coating is wetted by the fluid. In all the cases studied, capillary rise proceeds by a time-square law, but the mechanisms behind them (Lucas-Washburn or diffusive propagation) differ, depending on the chain length N. For a wettable wall, the speed of fluid imbibition decreases steadily with growing N, whereas the meniscus speed goes through a minimum at intermediate chain lengths. The polymer brush coating reorganizes into "channels" parallel to the tube axis and forms a dense plug of monomers in the vicinity of the meniscus, which moves with the meniscus along the nanotube. For lyophobic capillary walls (covered with a wettable polymer brush), depending on the chain length N, one finds three regimes: (1) short chains--one observes no meniscus motion, but an influx of fluid through the wet brush; (2) intermediate chain lengths--the fluid creates "fluid walls" inside the brush by diffusive spreading, whereby a meniscus is formed and moves up within the fluid walls; and (3) long chains--a "negative curvature" meniscus rises up the capillary by means of diffusive propagation. PMID:19426346

  13. Texture and wettability of metallic lotus leaves

    NASA Astrophysics Data System (ADS)

    Frankiewicz, C.; Attinger, D.

    2016-02-01

    Superhydrophobic surfaces with the self-cleaning behavior of lotus leaves are sought for drag reduction and phase change heat transfer applications. These superrepellent surfaces have traditionally been fabricated by random or deterministic texturing of a hydrophobic material. Recently, superrepellent surfaces have also been made from hydrophilic materials, by deterministic texturing using photolithography, without low-surface energy coating. Here, we show that hydrophilic materials can also be made superrepellent to water by chemical texturing, a stochastic rather than deterministic process. These metallic surfaces are the first analog of lotus leaves, in terms of wettability, texture and repellency. A mechanistic model is also proposed to describe the influence of multiple tiers of roughness on wettability and repellency. This demonstrated ability to make hydrophilic materials superrepellent without deterministic structuring or additional coatings opens the way to large scale and robust manufacturing of superrepellent surfaces.Superhydrophobic surfaces with the self-cleaning behavior of lotus leaves are sought for drag reduction and phase change heat transfer applications. These superrepellent surfaces have traditionally been fabricated by random or deterministic texturing of a hydrophobic material. Recently, superrepellent surfaces have also been made from hydrophilic materials, by deterministic texturing using photolithography, without low-surface energy coating. Here, we show that hydrophilic materials can also be made superrepellent to water by chemical texturing, a stochastic rather than deterministic process. These metallic surfaces are the first analog of lotus leaves, in terms of wettability, texture and repellency. A mechanistic model is also proposed to describe the influence of multiple tiers of roughness on wettability and repellency. This demonstrated ability to make hydrophilic materials superrepellent without deterministic structuring or additional coatings opens the way to large scale and robust manufacturing of superrepellent surfaces. Electronic supplementary information (ESI) available: Influence of the reaction parameters (temperature, concentration, time) on the surface texture and wettability, the estimation of roughness and solid fraction, drop impact measurements, EDS measurements, and durability tests. See DOI: 10.1039/c5nr04098a

  14. CO2 Reaction Induced Wettability Alteration and its Impacts on CO2 Storage: Pore to Core Scale Reservoir Condition Experimental Studies

    NASA Astrophysics Data System (ADS)

    Wan, J.; Tokunaga, T. K.; Kim, Y.; Jung, J.; Kim, T.; Dong, W.

    2013-12-01

    Wettability of the mineral surfaces plays an important role in subsurface multiphase flow and transport. Wettability affects the capillary pressure-saturation (Pc- S) relations, relative permeability (kr) of each fluid phase, and relative phase occupancy in reservoir pores. Although wettability issues have been studied extensively in other fields, significant knowledge gaps remain when applying the existing understanding to geological carbon sequestration; due largely to the unique physical-chemical properties of supercritical (sc) CO2 relative to other common non-wetting fluids such as air and oil. Here, we report our recent progress on wettability alteration upon reaction with CO2 and the resulting differences in capillary trapping of CO2 versus air. (1) Pore Scale Studies. There are conflict predictions in the literature concerning the effect of wettability on capillary trapping; some find that larger contact angles lead to lower capillary trapping while others have found opposite behavior. We hypothesized that spontaneous imbibition becomes energetically unfavorable with decreased wettability, so that increased residual trapping of scCO2 should occur during the post-injection inbibition stage. We developed a laboratory high-pressure and elevated temperature microscopic-micromodel system that is capable of controlling fine scale capillary pressure of scCO2-brine, and enabled us to conduct imbibition under controlled capillary pressures at the pore scale. We found that the de-wetting enhanced scCO2 capillary trapping is significant. These results suggest that scCO2 reaction induced dewetting can result in higher degrees of CO2 residual trapping in the post-injection stage than previously predicted. (2) Core Scale Studies. Capillary scaling is used routinely to predict Pc(S) relations for scCO2-brine systems at field scale, based on relations measured with air-water or mercury porosimetry. However, scaling-based predictions for CO2-brine systems have not been fully tested. Current limitations include the fact that imbibition curves are seldom measured due to experimental difficulties in controlling capillary pressure, and wettability (contact angles) is usually unknown and applied as adjustable parameters. Applying a new laboratory system to accurately control Pc at high total P, and we measured Pc(S) of a homogeneous quartz sand (selected because its 'normal' hydraulic properties are very well constrained). Drainage and imbibition experiments were conducted to directly measure Pc(S) with air-brine, then with scCO2-brine. With scCO2, intermediate levels of S shifted to Pc values 30% to 90% lower than predicted based on scaling with interfacial tension. Capillary trapping of CO2 were measured at Pc = 0 during brine imbibition, with trapped volumes for scCO2 significantly greater than for trapped air. We conclude that the observed deviations from scaling predictions make predicting the hydraulic behavior of scCO2 in reservoirs more challenging, and that an understanding of scCO2-induced wettability change is needed.

  15. Capillary muscle

    PubMed Central

    Cohen, Caroline; Mouterde, Timothée; Quéré, David; Clanet, Christophe

    2015-01-01

    The contraction of a muscle generates a force that decreases when increasing the contraction velocity. This “hyperbolic” force–velocity relationship has been known since the seminal work of A. V. Hill in 1938 [Hill AV (1938) Proc R Soc Lond B Biol Sci 126(843):136–195]. Hill’s heuristic equation is still used, and the sliding-filament theory for the sarcomere [Huxley H, Hanson J (1954) Nature 173(4412):973–976; Huxley AF, Niedergerke R (1954) Nature 173(4412):971–973] suggested how its different parameters can be related to the molecular origin of the force generator [Huxley AF (1957) Prog Biophys Biophys Chem 7:255–318; Deshcherevskiĭ VI (1968) Biofizika 13(5):928–935]. Here, we develop a capillary analog of the sarcomere obeying Hill’s equation and discuss its analogy with muscles. PMID:25944938

  16. Motion of Drops on Surfaces with Wettability Gradients

    NASA Technical Reports Server (NTRS)

    Subramanian, R. Shankar; McLaughlin, John B.; Moumen, Nadjoua; Qian, Dongying

    2002-01-01

    A liquid drop present on a solid surface can move because of a gradient in wettability along the surface, as manifested by a gradient in the contact angle. The contact angle at a given point on the contact line between a solid and a liquid in a gaseous medium is the angle between the tangent planes to the liquid and the solid surfaces at that point and is measured within the liquid side, by convention. The motion of the drop occurs in the direction of increasing wettability. The cause of the motion is the net force exerted on the drop by the solid surface because of the variation of the contact angle around the periphery. This force causes acceleration of an initially stationary drop, and leads to its motion in the direction of decreasing contact angle. The nature of the motion is determined by the balance between the motivating force and the resisting hydrodynamic force from the solid surface and the surrounding gaseous medium. A wettability gradient can be chemically induced as shown by Chaudhury and Whitesides who provided unambiguous experimental evidence that drops can move in such gradients. The phenomenon can be important in heat transfer applications in low gravity, such as when condensation occurs on a surface. Daniel et al have demonstrated that the velocity of a drop on a surface due to a wettability gradient in the presence of condensation can be more than two orders of magnitude larger than that observed in the absence of condensation. In the present research program, we have begun to study the motion of a drop in a wettability gradient systematically using a model system. Our initial efforts will be restricted to a system in which no condensation occurs. The experiments are performed as follows. First, a rectangular strip of approximate dimensions 10 x 20 mm is cut out of a silicon wafer. The strip is cleaned thoroughly and its surface is exposed to the vapor from an alkylchlorosilane for a period lasting between one and two minutes inside a desiccator. This is done using an approximate line source of the vapor in the form of a string soaked in the alkylchlorosilane. Ordinarily, many fluids, including water, wet the surface of silicon quite well. This means that the contact angle is small. But the silanized surface resists wetting, with contact angles that are as large as 100 degs. Therefore, a gradient of wettability is formed on the silicon surface. The region near the string is highly hydrophobic, and the contact angle decreases gradually toward a small value at the hydrophilic end away from this region. The change in wettability occurs over a distance of several mm. The strip is placed on a platform within a Plexiglas cell. Drops of a suitable liquid are introduced on top of the strip near the hydrophobic end. An optical system attached to a video camera is trained on the drop so that images of the moving drop can be captured on videotape for subsequent analysis. We have performed preliminary experiments with water as well as ethylene glycol drops. Results from these experiments will be presented in the poster. Future plans include the refinement of the experimental system so as to permit images to be recorded from the side as well as the top, and the conduct of a systematic study in which the drop size is varied over a good range. Experiments will be conducted with different fluids so as to obtain the largest possible range of suitably defined Reynolds and Capillary numbers. Also, an effort will be initiated on theoretical modeling of this motion. The challenges in the development of the theoretical description lie in the proper analysis of the region in the vicinity of the contact line, as well as in the free boundary nature of the problem. It is known that continuum models assuming the no slip condition all the way to the contact line fail by predicting that the stress on the solid surface becomes singular as the contact line is approached. One approach for dealing with this issue has been to relax the no-slip boundary condition using the Navier model. Molecular dynamics simulations of the contact li

  17. Motion of Drops on Surfaces with Wettability Gradients

    NASA Astrophysics Data System (ADS)

    Subramanian, R. Shankar; McLaughlin, John B.; Moumen, Nadjoua; Qian, Dongying

    2002-11-01

    A liquid drop present on a solid surface can move because of a gradient in wettability along the surface, as manifested by a gradient in the contact angle. The contact angle at a given point on the contact line between a solid and a liquid in a gaseous medium is the angle between the tangent planes to the liquid and the solid surfaces at that point and is measured within the liquid side, by convention. The motion of the drop occurs in the direction of increasing wettability. The cause of the motion is the net force exerted on the drop by the solid surface because of the variation of the contact angle around the periphery. This force causes acceleration of an initially stationary drop, and leads to its motion in the direction of decreasing contact angle. The nature of the motion is determined by the balance between the motivating force and the resisting hydrodynamic force from the solid surface and the surrounding gaseous medium. A wettability gradient can be chemically induced as shown by Chaudhury and Whitesides who provided unambiguous experimental evidence that drops can move in such gradients. The phenomenon can be important in heat transfer applications in low gravity, such as when condensation occurs on a surface. Daniel et al have demonstrated that the velocity of a drop on a surface due to a wettability gradient in the presence of condensation can be more than two orders of magnitude larger than that observed in the absence of condensation. In the present research program, we have begun to study the motion of a drop in a wettability gradient systematically using a model system. Our initial efforts will be restricted to a system in which no condensation occurs. The experiments are performed as follows. First, a rectangular strip of approximate dimensions 10 x 20 mm is cut out of a silicon wafer. The strip is cleaned thoroughly and its surface is exposed to the vapor from an alkylchlorosilane for a period lasting between one and two minutes inside a desiccator. This is done using an approximate line source of the vapor in the form of a string soaked in the alkylchlorosilane. Ordinarily, many fluids, including water, wet the surface of silicon quite well. This means that the contact angle is small. But the silanized surface resists wetting, with contact angles that are as large as 100 degs. Therefore, a gradient of wettability is formed on the silicon surface. The region near the string is highly hydrophobic, and the contact angle decreases gradually toward a small value at the hydrophilic end away from this region. The change in wettability occurs over a distance of several mm. The strip is placed on a platform within a Plexiglas cell. Drops of a suitable liquid are introduced on top of the strip near the hydrophobic end. An optical system attached to a video camera is trained on the drop so that images of the moving drop can be captured on videotape for subsequent analysis. We have performed preliminary experiments with water as well as ethylene glycol drops. Results from these experiments will be presented in the poster. Future plans include the refinement of the experimental system so as to permit images to be recorded from the side as well as the top, and the conduct of a systematic study in which the drop size is varied over a good range. Experiments will be conducted with different fluids so as to obtain the largest possible range of suitably defined Reynolds and Capillary numbers. Also, an effort will be initiated on theoretical modeling of this motion. The challenges in the development of the theoretical description lie in the proper analysis of the region in the vicinity of the contact line, as well as in the free boundary nature of the problem. It is known that continuum models assuming the no slip condition all the way to the contact line fail by predicting that the stress on the solid surface becomes singular as the contact line is approached. One approach for dealing with this issue has been to relax the no-slip boundary condition using the Navier model. Molecular dynamics simulations of the contact line region show that for a non-polar liquid on a solid surface, the no-slip boundary condition is in fact incorrect near the contact line. Furthermore, the same simulations also show that the usual relationship between stress and the rate of deformation breaks down in the vicinity of the contact line. In developing continuum theoretical models of the system, we shall accommodate this knowledge to the extent possible.

  18. Motion of Drops on Surfaces with Wettability Gradients

    NASA Technical Reports Server (NTRS)

    Subramanian, R. Shankar; McLaughlin, John B.; Moumen, Nadjoua; Qian, Dongying

    2002-01-01

    A liquid drop present on a solid surface can move because of a gradient in wettability along the surface, as manifested by a gradient in the contact angle. The contact angle at a given point on the contact line between a solid and a liquid in a gaseous medium is the angle between the tangent planes to the liquid and the solid surfaces at that point and is measured within the liquid side, by convention. The motion of the drop occurs in the direction of increasing wettability. The cause of the motion is the net force exerted on the drop by the solid surface because of the variation of the contact angle around the periphery. This force causes acceleration of an initially stationary drop, and leads to its motion in the direction of decreasing contact angle. The nature of the motion is determined by the balance between the motivating force and the resisting hydrodynamic force from the solid surface and the surrounding gaseous medium. A wettability gradient can be chemically induced as shown by Chaudhury and Whitesides who provided unambiguous experimental evidence that drops can move in such gradients. The phenomenon can be important in heat transfer applications in low gravity, such as when condensation occurs on a surface. Daniel et al have demonstrated that the velocity of a drop on a surface due to a wettability gradient in the presence of condensation can be more than two orders of magnitude larger than that observed in the absence of condensation. In the present research program, we have begun to study the motion of a drop in a wettability gradient systematically using a model system. Our initial efforts will be restricted to a system in which no condensation occurs. The experiments are performed as follows. First, a rectangular strip of approximate dimensions 10 x 20 mm is cut out of a silicon wafer. The strip is cleaned thoroughly and its surface is exposed to the vapor from an alkylchlorosilane for a period lasting between one and two minutes inside a desiccator. This is done using an approximate line source of the vapor in the form of a string soaked in the alkylchlorosilane. Ordinarily, many fluids, including water, wet the surface of silicon quite well. This means that the contact angle is small. But the silanized surface resists wetting, with contact angles that are as large as 100 degs. Therefore, a gradient of wettability is formed on the silicon surface. The region near the string is highly hydrophobic, and the contact angle decreases gradually toward a small value at the hydrophilic end away from this region. The change in wettability occurs over a distance of several mm. The strip is placed on a platform within a Plexiglas cell. Drops of a suitable liquid are introduced on top of the strip near the hydrophobic end. An optical system attached to a video camera is trained on the drop so that images of the moving drop can be captured on videotape for subsequent analysis. We have performed preliminary experiments with water as well as ethylene glycol drops. Results from these experiments will be presented in the poster. Future plans include the refinement of the experimental system so as to permit images to be recorded from the side as well as the top, and the conduct of a systematic study in which the drop size is varied over a good range. Experiments will be conducted with different fluids so as to obtain the largest possible range of suitably defined Reynolds and Capillary numbers. Also, an effort will be initiated on theoretical modeling of this motion. The challenges in the development of the theoretical description lie in the proper analysis of the region in the vicinity of the contact line, as well as in the free boundary nature of the problem. It is known that continuum models assuming the no slip condition all the way to the contact line fail by predicting that the stress on the solid surface becomes singular as the contact line is approached. One approach for dealing with this issue has been to relax the no-slip boundary condition using the Navier model. Molecular dynamics simulations of the contact line region show that for a non-polar liquid on a solid surface, the no-slip boundary condition is in fact incorrect near the contact line. Furthermore, the same simulations also show that the usual relationship between stress and the rate of deformation breaks down in the vicinity of the contact line. In developing continuum theoretical models of the system, we shall accommodate this knowledge to the extent possible.

  19. Immiscible fluids in mixed wet porous media: the role of wettability correlations

    NASA Astrophysics Data System (ADS)

    Murison, Julie; Semin, Benoit; Baret, Jean-Christophe; Herminghaus, Stephan; Schroeter, Matthias; Brinkmann, Martin

    2013-11-01

    Various phenomena observed during immiscible displacement in a porous medium can be related to pore wall wettability. Petroleum engineers traditionally quantify the overall wettability of a rock sample in terms of the Ammot-Harvey or USBM index. To establish a link between these gloabl quantities and the pore-scale distribution of surface energies, we developed a series of model porous media. Using a variety of preparation methods, we are able to create dense beds of glass beads with the same average surface energy, differing only in the typical extension of the wetting and non-wetting surface domains. Experimental measurements of capillary pressure saturation curves for repeated imbibition and drainage show that the work dissipated in a complete cycle is monotonically increasing with the correlation length ξ of the surface energies. To test whether capillary hysteresis can be linked to specific features of the front morphology, we visualized the distribution of liquids by means of X-ray microtomography. The Minkowski measures volume, surface area, and Euler number are employed to characterize the interfacial shape. Differences of the front morphology during imbibition and drainage match with trends observed for the hysteresis loop opening.

  20. Bioinspired steel surfaces with extreme wettability contrast

    NASA Astrophysics Data System (ADS)

    Her, Eun Kyu; Ko, Tae-Jun; Lee, Kwang-Ryeol; Oh, Kyu Hwan; Moon, Myoung-Woon

    2012-04-01

    The exterior structures of natural organisms have continuously evolved by controlling wettability, such as the Namib Desert beetle, whose back has hydrophilic/hydrophobic contrast for water harvesting by mist condensation in dry desert environments, and some plant leaves that have hierarchical micro/nanostructures to collect or repel liquid water. In this work, we have provided a method for wettability contrast on alloy steels by both nano-flake or needle patterns and tuning of the surface energy. Steels were provided with hierarchical micro/nanostructures of Fe oxides by fluorination and by a subsequent catalytic reaction of fluorine ions on the steel surfaces in water. A hydrophobic material was deposited on the structured surfaces, rendering superhydrophobicity. Plasma oxidization induces the formation of superhydrophilic surfaces on selective regions surrounded by superhydrophobic surfaces. We show that wettability contrast surfaces align liquid water within patterned hydrophilic regions during the condensation process. Furthermore, this method could have a greater potential to align other liquids or living cells.The exterior structures of natural organisms have continuously evolved by controlling wettability, such as the Namib Desert beetle, whose back has hydrophilic/hydrophobic contrast for water harvesting by mist condensation in dry desert environments, and some plant leaves that have hierarchical micro/nanostructures to collect or repel liquid water. In this work, we have provided a method for wettability contrast on alloy steels by both nano-flake or needle patterns and tuning of the surface energy. Steels were provided with hierarchical micro/nanostructures of Fe oxides by fluorination and by a subsequent catalytic reaction of fluorine ions on the steel surfaces in water. A hydrophobic material was deposited on the structured surfaces, rendering superhydrophobicity. Plasma oxidization induces the formation of superhydrophilic surfaces on selective regions surrounded by superhydrophobic surfaces. We show that wettability contrast surfaces align liquid water within patterned hydrophilic regions during the condensation process. Furthermore, this method could have a greater potential to align other liquids or living cells. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr11934j

  1. Nanowear of salivary films vs. substratum wettability.

    PubMed

    Sotres, J; Pettersson, T; Lindh, L; Arnebrant, T

    2012-10-01

    The pellicle serves as a multifunctional protective layer, providing, e.g., lubrication and remineralization and also acting as a diffusion barrier. In addition, since the formation of the pellicle precedes the adhesion of micro-organisms, it is also important as a conditioning film. We present a novel approach to study the influence of the water wettability of solid surfaces on the strength of adsorbed salivary films. It is based on studying the wear resistance of the films with an atomic force microscope operated in the friction force spectroscopy mode. This methodology provides the strength of the films in terms of the forces needed for breaking and removing them. Our results indicate that these forces are highly dependent on the water wettability of the underlying substrata, decreasing with increasing hydrophobicity. Thus, this study provides valuable information for the design of materials exposed in the oral cavity, i.e., materials that will minimize plaque formation and be easy to clean. PMID:22875480

  2. Texture and wettability of metallic lotus leaves.

    PubMed

    Frankiewicz, C; Attinger, D

    2016-02-11

    Superhydrophobic surfaces with the self-cleaning behavior of lotus leaves are sought for drag reduction and phase change heat transfer applications. These superrepellent surfaces have traditionally been fabricated by random or deterministic texturing of a hydrophobic material. Recently, superrepellent surfaces have also been made from hydrophilic materials, by deterministic texturing using photolithography, without low-surface energy coating. Here, we show that hydrophilic materials can also be made superrepellent to water by chemical texturing, a stochastic rather than deterministic process. These metallic surfaces are the first analog of lotus leaves, in terms of wettability, texture and repellency. A mechanistic model is also proposed to describe the influence of multiple tiers of roughness on wettability and repellency. This demonstrated ability to make hydrophilic materials superrepellent without deterministic structuring or additional coatings opens the way to large scale and robust manufacturing of superrepellent surfaces. PMID:26537609

  3. How does surface wettability influence nucleate boiling?

    NASA Astrophysics Data System (ADS)

    Phan, Hai Trieu; Caney, Nadia; Marty, Philippe; Colasson, Stphane; Gavillet, Jrme

    2009-05-01

    Although the boiling process has been a major subject of research for several decades, its physics still remain unclear and require further investigation. This study aims at highlighting the effects of surface wettability on pool boiling heat transfer. Nanocoating techniques were used to vary the water contact angle from 20 to 110 by modifying nanoscale surface topography and chemistry. The experimental results obtained disagree with the predictions of the classical models. A new approach of nucleation mechanism is established to clarify the nexus between the surface wettability and the nucleate boiling heat transfer. In this approach, we introduce the concept of macro- and micro-contact angles to explain the observed phenomenon. To cite this article: H.T. Phan et al., C. R. Mecanique 337 (2009).

  4. Nanofluids alter the surface wettability of solids.

    PubMed

    Lim, Sangwook; Horiuchi, Hiroki; Nikolov, Alex D; Wasan, Darsh

    2015-06-01

    We report the results of our studies on the changes in the contact angle and interfacial tension using a nanofluid composed of silica nanoparticles dispersed in water on three different solid substrates: gold (partially hydrophobic), glass (hydrophilic), and a silicon wafer (hydrophilic). We used both the goniometric method and drop-shape analysis to make the measurements. On the basis of the results of the drop-shape analysis using the Laplace equation, we evaluated the contributions of the interfacial tension change to the equilibrium contact angle and the presence of nanoparticles near the solid substrate, thereby elucidating the change in the wettability of the solid substrate. We found that the nanoparticles decrease the contact angle of the substrate with the increase in the nanoparticle concentration. To rationalize our experimental observations on the decrease in the contact angle of the solid substrate in the presence of nanoparticles, we calculated the surface volume fraction of the nanoparticles in the layer near the solid substrate using the particle layering model (based on the nanoparticles' excluded volume effect). We found that the volume fraction of the nanoparticles in the layer close to the substrate increased with an increase in the nanoparticle volume fraction in the bulk and correlated qualitatively with the change in the substrate wettability. The extent of the wettability alteration depends on the volume fraction of the nanoparticles, their size, and the type of substrate. We found a strong correlation between the change in the substrate wettability and the nanoparticle volume fraction in the layer closer to the substrate surface. PMID:25919686

  5. Dependence of capillary forces on relative humidity and the surface properties of femtosecond laser micromachined titanium.

    PubMed

    Lehr, Jorge; Kietzig, Anne-Marie

    2015-06-15

    Capillary forces were measured with colloidal atomic force microscopy at different levels of relative humidity on femtosecond laser micromachined titanium surfaces. After laser machining at different intensity levels, the titanium surfaces show a nanoscale ripple topology or microscopic bumpy structures. Different machining environments were chosen to influence the surface chemistry in addition to topology: while machining in pure oxygen and water resulted in surfaces consisting of TiO2, a composite surface of TiO2 and TiN was obtained after machining in pure nitrogen. All samples were subsequently exposed to pure oxygen, carbon dioxide or water, and showed different levels of wettability and capillary force. We have introduced the concept of humidity sensitivity as the relative increase of the capillary force with respect to the measured force at 0% humidity. We report that samples with a nanoscale ripple topology machined in pure oxygen exhibit the lowest level of capillary force and the lowest sensitivity towards humidity in the environment. Surfaces with low sensitivity towards changes of the relative humidity are good candidates for technical applications, where capillary forces have to be controlled. This study contributes to the development of such surfaces, to a better understanding of how capillary bridges are formed on rough surfaces and ultimately to the exploration of the relationship between surface wettability and capillary forces. PMID:25746189

  6. Rapid capillary filling via ion-water interactions over the nanoscale.

    PubMed

    Bakli, Chirodeep; Chakraborty, Suman

    2016-03-17

    Giant frictional resistances are grand challenges against the rapid filling of nanoscale capillaries, as encountered in a wide variety of applications ranging from nature to energy. It is commonly believed that partially wettable charged nanocapillaries fill up considerably slower, compared to completely wettable ones, under the influence of a complex interplay between interfacial tension and electrical interactions. In sharp contrast to this common belief, here we discover a new non-intuitive regime of rapid filling of charged capillaries over the nanometer scale, by virtue of which a partially wettable capillary may fill up comparatively faster than a completely wettable one. We attribute the fundamental origin of this remarkable behavior to ion-water interactions over interfacial scales. The underlying novel electro-hydrodynamic mechanism, as unveiled here, may provide deeper insights into the physico-chemical interactions leading to augmentations in the rates of nanocapillary filling over hydrophobic regimes, bearing far-reaching implications in the transport of biological fluids, enhanced oil recovery, and miniaturized energy harvesting applications. PMID:26935707

  7. Particle Segregation at Contact Lines of Evaporating Colloidal Drops: Influence of the Substrate Wettability and Particle Charge-Mass Ratio.

    PubMed

    Noguera-Marín, Diego; Moraila-Martínez, Carmen L; Cabrerizo-Vílchez, Miguel A; Rodríguez-Valverde, Miguel A

    2015-06-23

    Segregation of particles during capillary/convective self-assembly is interesting for self-stratification in colloidal deposits. In evaporating drops containing colloidal particles, the wettability properties of substrate and the sedimentation of particles can affect their accumulation at contact lines. In this work we studied the size segregation and discrimination of charged particles with different densities. We performed in-plane particle counting at evaporating triple lines by using fluorescence confocal microscopy. We studied separately substrates with very different wettability properties and particles with different charge-mass ratios at low ionic strength. We used binary colloidal suspensions to compare simultaneously the deposition of two different particles. The particle deposition rate strongly depends on the receding contact angle of the substrate. We further observed a singular behavior of charged polystyrene particles in binary mixtures under "salt-free" conditions explained by the "colloidal Brazil nut" effect. PMID:26000909

  8. Leaf wettability decreases along an extreme altitudinal gradient.

    PubMed

    Aryal, Biva; Neuner, Gilbert

    2010-01-01

    The duration and amount of water captured on leaves and its functional significance is highly varied. Leaf surface wettability influences water absorption, gas exchange, pathogen infection, nutrient leaching, contamination by pollutants, self-cleaning properties and in freezing environments the probability of extrinsic ice nucleation. To test the impact of environment on the development of leaf wettability, this functional trait was measured in 227 dominant plant species along an extreme altitudinal environment gradient (186-5,268 m) on the wet and dry slopes of the Nepalese Himalayas. Plants from the understorey and open places in woodlands were also compared. Leaf wettability was assessed by droplet contact angle (theta), retention and leaf inclination measurement. With increasing altitude leaf wettability decreased significantly parallel to the observed atmospheric temperature decrease (0.5 K/100 m). Leaves from non-freezing tropical and subtropical origins were highly wettable (theta < 90 degrees). Temperate leaves were non-wettable (110 degrees < theta < 130 degrees). Subalpine and alpine leaves were highly non-wettable (130 degrees < theta < 150 degrees) and adaxial pubescence occurred more frequently. Leaves taken from the understorey were more wettable but had a better droplet run off than leaves sampled in open places. In the semi-arid northern slopes (temperate to alpine) of the Himalayas leaf wettability was decreased in comparison to the southern humid side. The majority of the leaves had a low droplet retention <20 degrees ; higher values were linked to high non-wettability (theta > 130 degrees) which was more often observed at high altitude. Good droplet run off at +/-10 degrees inclination was found in highly wettable leaves (theta < 90 degrees) of tropical and subtropical origin and on leaves from the forest understorey. Structural properties for low wettability are developed in cold and dry environments and open sites with frequent dew formation as it appears to be an important functional trait to prevent a number of the negative effects adhering surface water may have. PMID:19727830

  9. Wettability patterning of hydroxyapatite nanobioceramics induced by surface potential modification

    SciTech Connect

    Aronov, D.; Rosenman, G.; Karlov, A.; Shashkin, A.

    2006-04-17

    Hydroxyapatite is known as a substrate for effective adhesion of various biological cells and bacteria as well implantable biomimetic material replacing defective bone tissues. It is found that low energy electron irradiation induces its strong surface potential variation and gives rise to pronounced wettability modification. The found electron-modulation method of the hydroxyapatite wettability enables both wettability switching and its microscopic patterning, which may be used for fabrication of spatially arrayed hydroxyapatite for biological cells immobilization, gene transfer, etc.

  10. Effect of wettability on scale-up of multiphase flow from core-scale to reservoir fine-grid-scale

    SciTech Connect

    Chang, Y.C.; Mani, V.; Mohanty, K.K.

    1997-08-01

    Typical field simulation grid-blocks are internally heterogeneous. The objective of this work is to study how the wettability of the rock affects its scale-up of multiphase flow properties from core-scale to fine-grid reservoir simulation scale ({approximately} 10{prime} x 10{prime} x 5{prime}). Reservoir models need another level of upscaling to coarse-grid simulation scale, which is not addressed here. Heterogeneity is modeled here as a correlated random field parameterized in terms of its variance and two-point variogram. Variogram models of both finite (spherical) and infinite (fractal) correlation length are included as special cases. Local core-scale porosity, permeability, capillary pressure function, relative permeability functions, and initial water saturation are assumed to be correlated. Water injection is simulated and effective flow properties and flow equations are calculated. For strongly water-wet media, capillarity has a stabilizing/homogenizing effect on multiphase flow. For small variance in permeability, and for small correlation length, effective relative permeability can be described by capillary equilibrium models. At higher variance and moderate correlation length, the average flow can be described by a dynamic relative permeability. As the oil wettability increases, the capillary stabilizing effect decreases and the deviation from this average flow increases. For fractal fields with large variance in permeability, effective relative permeability is not adequate in describing the flow.

  11. Capillary Driven Flows Along Differentially Wetted Interior Corners

    NASA Technical Reports Server (NTRS)

    Golliher, Eric L. (Technical Monitor); Nardin, C. L.; Weislogel, M. M.

    2005-01-01

    Closed-form analytic solutions useful for the design of capillary flows in a variety of containers possessing interior corners were recently collected and reviewed. Low-g drop tower and aircraft experiments performed at NASA to date show excellent agreement between theory and experiment for perfectly wetting fluids. The analytical expressions are general in terms of contact angle, but do not account for variations in contact angle between the various surfaces within the system. Such conditions may be desirable for capillary containment or to compute the behavior of capillary corner flows in containers consisting of different materials with widely varying wetting characteristics. A simple coordinate rotation is employed to recast the governing system of equations for flows in containers with interior corners with differing contact angles on the faces of the corner. The result is that a large number of capillary driven corner flows may be predicted with only slightly modified geometric functions dependent on corner angle and the two (or more) contact angles of the system. A numerical solution is employed to verify the new problem formulation. The benchmarked computations support the use of the existing theoretical approach to geometries with variable wettability. Simple experiments to confirm the theoretical findings are recommended. Favorable agreement between such experiments and the present theory may argue well for the extension of the analytic results to predict fluid performance in future large length scale capillary fluid systems for spacecraft as well as for small scale capillary systems on Earth.

  12. Water films, asphaltenes, and wettability alteration

    SciTech Connect

    Kaminsky, R.; Radke, C.J.

    1998-06-01

    We present a transport model for asphaltene diffusion from an oil/water interface through a water film followed by adsorption at a solid/water interface. Using a Langmuir adsorption isotherm, the effect of asphaltene aqueous solubility and adsorption constant K on equilibration time are established. For K greater than 1 nm and asphaltene solubilities down to 0.1 ppb, adsorption equilibrium, taken to be 1 mg/m{sup 2}, occurs within a few hours. Negligible asphaltene solubility does not explain why a water film prevents asphaltene adsorption and wettability alteration in reservoir rock.

  13. The effects of fractional wettability on microbial enhanced oil recovery

    NASA Astrophysics Data System (ADS)

    Wildenschild, D.; Armstrong, R. T.

    2011-12-01

    Microbial enhanced oil recovery (MEOR) is a tertiary oil recovery technology that has had inconsistent success at the field-scale, while lab-scale experiments are mostly successful. One potential reason for these inconsistencies is that the efficacy of MEOR in fractional-wet systems is unknown. Our MEOR strategy consists of the injection of ex situ produced metabolic byproducts produced by Bacillus mojavensis JF-2 (that lower interfacial tension via biosurfactant production) into fractional-wet cores containing residual oil. Fractional-wet cores tested were 50%, 25%, and 0% oil-wet and two different MEOR flooding solutions were tested; one solution contained both microbes and metabolic byproducts while the other contained only the metabolic byproducts. The columns were imaged with x-ray computed microtomography (CMT) after water flooding, and after MEOR, which allowed for the evaluation of the pore-scale processes taking place during MEOR and wettability effects. Results indicate that during MEOR the larger residual oil blobs in mostly fractional-wet pores and residual oil held under relatively low capillary pressures were the main fractions recovered, while residual oil blobs in purely oil-wet pores remained in place. Residual oil saturation, interfacial curvatures, and oil blob sizes were measured from the CMT images and used to develop a conceptual model for MEOR in fractional-wet systems. Overall, results indicate that MEOR was effective at recovering oil from fractional-wet systems with reported additional oil recovered (AOR) values between 44% and 80%; the highest AOR values were observed in the most oil-wet system.

  14. Capillary Origami Controlled by Electrowetting

    NASA Astrophysics Data System (ADS)

    Pineirua, Miguel; Bico, Jose; Roman, Benoit

    2010-03-01

    What happens if a water droplet is deposited over an elastic sheet? The sheet spontaneously wraps around droplet? This is possible if the capillary forces due to the liquid/air interface overcome the bending stiffness of the elastic sheet [1]. This technique called ``capillary origami'' could be used not only to encapsulate micro droplets but also to produce 3-D objects out from planar patterns. Once the microstructure has closed, could it be possible to reopen it at will? The wetting properties of liquids can be modified by the action of an electric field [2]. This phenomenon known as electrowetting can be seen as the electric energy minimization of a capacitor. In order to be capable of reopening the capillary origami, we propose to apply an electric field between the droplet and the substrate, with the flexible sheet as an isolating layer between them. The sheet will stay wrapping the droplet while the circuit is open and will eventually unwrap it if a sufficiently intense electric field is applied. We attempt to describe the original interaction between the electric field, capillarity and elasticity.[4pt] [1] C. Py, P. Reverdy, L. Doppler, J. Bico, B. Roman, C.N.Baroud, Capillary origami : spontaneous wrapping of a droplet with an elastic sheet, Phys. Rev. Lett., 98, 156103 (2007).[0pt] [2] F. Mugele, J.-C. Baret, Electrowetting : from basics to applications, J. Phys. Cond. Mat., 17, R705 (2005).

  15. Wettability gradient colorimetric sensing by amphiphilic molecular response.

    PubMed

    Hong, Wei; Li, Haoran; Hu, Xiaobin; Zhao, Binyuan; Zhang, Fan; Zhang, Di; Xu, Zhou

    2013-01-25

    Herein we present a highly sensitive sensing method combining amphiphilic molecules and wettability gradient photonic hydrogels for molecular recognition and chemical sensing applications. These wettability gradient photonic films exhibit low analyte amount, fast response, as well as interference resistance, which enable them for applications in forgery detection and visual determination of analyte concentrations. PMID:23228952

  16. Theoretical study on wettability of graphene/water interface

    NASA Astrophysics Data System (ADS)

    Ishimoto, Takayoshi

    2015-12-01

    We analyzed the interaction energy between water clusters and graphene model compound by using density functional theory. The mono- and multi-layer interaction of water on graphene models are regarded as the low and high contact angles, which correspond to the wettability of interface, respectively. We clearly found the size dependency of water molecules on graphene model compound for the wettability.

  17. Wettability control by DLC coated nanowire topography

    NASA Astrophysics Data System (ADS)

    Li, Zihui; Meng, Fanhao; Liu, Xuanyong

    2011-04-01

    Here we have developed a convenient method to fabricate wettability controllable surfaces that can be applied to various nanostructured surfaces with complex shapes for different industrial needs. Diamond-like carbon (DLC) films were synthesized on titanium substrate with a nanowire structured surface using plasma immersion ion implantation and deposition (PIII&D). The nanostructure of the DLC films was characterized by field emission scanning electron microscopy and found to grow in a rippling layer-by-layer manner. Raman spectroscopy was used to investigate the different bonding presented in the DLC films. To determine the wettability of the samples, water contact angles were measured and found to vary in the range of 50-141. The results indicated that it was critical to construct a proper surface topography for high hydrophobicity, while suitable ID/IG and sp2/sp3 ratios of the DLC films had a minor contribution. Superhydrophobicity could be achieved by further CF4 implantation on suitably structured DLC films and was attributed to the existence of fluorine. In order to maintain the nanostructure during CF4 implantation, it was favorable to pre-deposit an appropriate carbon content on the nanostructure, as a nanostructure with low carbon content would be deformed during CF4 implantation due to local accumulation of surface charge and the following discharge resulting from the low conductivity.

  18. Wettability control by DLC coated nanowire topography.

    PubMed

    Li, Zihui; Meng, Fanhao; Liu, Xuanyong

    2011-04-01

    Here we have developed a convenient method to fabricate wettability controllable surfaces that can be applied to various nanostructured surfaces with complex shapes for different industrial needs. Diamond-like carbon (DLC) films were synthesized on titanium substrate with a nanowire structured surface using plasma immersion ion implantation and deposition (PIII&D). The nanostructure of the DLC films was characterized by field emission scanning electron microscopy and found to grow in a rippling layer-by-layer manner. Raman spectroscopy was used to investigate the different bonding presented in the DLC films. To determine the wettability of the samples, water contact angles were measured and found to vary in the range of 50-141. The results indicated that it was critical to construct a proper surface topography for high hydrophobicity, while suitable I(D)/I(G) and sp/sp ratios of the DLC films had a minor contribution. Superhydrophobicity could be achieved by further CF? implantation on suitably structured DLC films and was attributed to the existence of fluorine. In order to maintain the nanostructure during CF? implantation, it was favorable to pre-deposit an appropriate carbon content on the nanostructure, as a nanostructure with low carbon content would be deformed during CF? implantation due to local accumulation of surface charge and the following discharge resulting from the low conductivity. PMID:21343636

  19. Pool boiling of nanoparticle-modified surface with interlaced wettability

    NASA Astrophysics Data System (ADS)

    Hsu, Chin-Chi; Su, Tsung-Wen; Chen, Ping-Hei

    2012-05-01

    This study investigated the pool boiling heat transfer under heating surfaces with various interlaced wettability. Nano-silica particles were used as the coating element to vary the interlaced wettability of the surface. The experimental results revealed that when the wettability of a surface is uniform, the critical heat flux increases with the more wettable surface; however, when the wettability of a surface is modified interlacedly, regardless of whether the modified region becomes more hydrophilic or hydrophobic, the critical heat flux is consistently higher than that of the isotropic surface. In addition, this study observed that critical heat flux was higher when the contact angle difference between the plain surface and the modified region was smaller.

  20. Pool boiling of nanoparticle-modified surface with interlaced wettability

    PubMed Central

    2012-01-01

    This study investigated the pool boiling heat transfer under heating surfaces with various interlaced wettability. Nano-silica particles were used as the coating element to vary the interlaced wettability of the surface. The experimental results revealed that when the wettability of a surface is uniform, the critical heat flux increases with the more wettable surface; however, when the wettability of a surface is modified interlacedly, regardless of whether the modified region becomes more hydrophilic or hydrophobic, the critical heat flux is consistently higher than that of the isotropic surface. In addition, this study observed that critical heat flux was higher when the contact angle difference between the plain surface and the modified region was smaller. PMID:22607462

  1. Water transport mechanism through open capillaries analyzed by direct surface modifications on biological surfaces

    NASA Astrophysics Data System (ADS)

    Ishii, Daisuke; Horiguchi, Hiroko; Hirai, Yuji; Yabu, Hiroshi; Matsuo, Yasutaka; Ijiro, Kuniharu; Tsujii, Kaoru; Shimozawa, Tateo; Hariyama, Takahiko; Shimomura, Masatsugu

    2013-10-01

    Some small animals only use water transport mechanisms passively driven by surface energies. However, little is known about passive water transport mechanisms because it is difficult to measure the wettability of microstructures in small areas and determine the chemistry of biological surfaces. Herein, we developed to directly analyse the structural effects of wettability of chemically modified biological surfaces by using a nanoliter volume water droplet and a hi-speed video system. The wharf roach Ligia exotica transports water only by using open capillaries in its legs containing hair- and paddle-like microstructures. The structural effects of legs chemically modified with a self-assembled monolayer were analysed, so that the wharf roach has a smart water transport system passively driven by differences of wettability between the microstructures. We anticipate that this passive water transport mechanism may inspire novel biomimetic fluid manipulations with or without a gravitational field.

  2. Wettability phenomena at the CO2-brine-mineral interface: implications for geologic carbon sequestration.

    PubMed

    Wang, Shibo; Edwards, Ian M; Clarens, Andres F

    2013-01-01

    Geologic carbon sequestration (GCS) in deep saline aquifers results in chemical and transport processes that are impacted by the wettability characteristics of formation solid phases in contact with connate brines and injected CO(2). Here, the contact angle (?) at the CO(2)-brine-mineral interface is studied for several representative solids including quartz, microcline, calcite, kaolinite, phlogopite, and illite under a range of GCS conditions. All were found to be water wetting (? < 30) with subtle but important differences in contact angles observed between the surfaces. Temperature and pressure conditions affected the results but did not produce discernible trends common to all surfaces. Brine composition, in terms of pH and ionic strength, was a better predictor of interfacial behavior. For the nonclays, the wettability is impacted by the pH at the point of zero charge of the solid. For the clays, the response was more complex. Under nonequilibrium conditions, hysteretic effects were observed when CO(2) was dissolving into the bulk fluid and this effect varied between minerals. Contact angle was found to decrease during the CO(2) phase transition from supercritical or liquid phase to gas phase. These results are useful for developing a more complete understanding of leakage through caprocks and capillary trapping in GCS. PMID:22857395

  3. Microscale fibre alignment by a three-dimensional sessile drop on a wettable pad

    NASA Astrophysics Data System (ADS)

    Reznik, S. N.; Salalha, W.; Yarin, A. L.; Zussman, E.

    Fluidic assembly provides solutions for assembling particles with sizes from nano- metres to centimetres. Fluidic techniques based on patterned shapes of monolayers and capillary forces are widely used to assemble microfabrication devices. Usually, for self-assembly, the precondition is that the components must be mobile in a fluidic environment. In the present work, a shape-directed fluidic self-assembly of rod-like microstructures, such as an optical fibre on a wettable pad is demonstrated experimentally with submicrometre positioning precision. A model of the process is proposed, which accounts for the following two stages of the orientation of a fibre submerged in a sessile drop: (i) the drop melting and spreading over a wettable pad; (ii) fibre reorientation related to the surface-tension-driven shrinkage of the drop surface area. At the end of stage (ii), the fibre is oriented along the pad. The experi- mental results for the optical-fibre assembly by a solder joint have been compared to the modelling results, and a reasonable agreement has been found. The major outcome of the experiments and modelling is that surface tension forces on the fibre piercing a drop align the fibre rather than the flow owing to the spreading of the drop over the horizontal pad, i.e. stage (ii) mostly contributes to the alignment.

  4. Wettability control and flow regulation using a nanostructure-embedded surface.

    PubMed

    Tafti, Ehsan Yakhshi; Londe, Ghanashyam; Chunder, Anindarupa; Zhai, Lei; Kumar, Ranganathan; Cho, Hyoung J

    2011-02-01

    This work addresses the synthesis, integration and characterization of a nanostructure-embedded thermoresponsive surface for flow regulation. In order to create a hierarchic structure which consists of microscale texture and nanoscale sub-texture, hybrid multilayers consisting of poly(allylamine hydrochloride) (PAH), poly(acrylic acid) (PAA) and colloidal silica nanoparticles (average diameter = 22 nm and 7 nm) were used. Based on the electrostatic interactions between the polyelectrolytes and nanoparticles, a layer-by-layer deposition technique in combination with photolithography was employed to obtain a localized, conformally-coated patch in a microchannel. Grafted with the thermoresponsive polymer, poly(N-isopropylacrylamide) (PNIPAAm), wettability of the surface could be tuned upon heating or cooling. The measurement of differential pressure at various stages of device verified the working conditions of the nanostructure-embedded surface for regulating a capillary flow in the microchannel. PMID:21456202

  5. Stick-Slip Control in Nanoscale Boundary Lubrication by Surface Wettability

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Foster, Adam S.; Alava, Mikko J.; Laurson, Lasse

    2015-03-01

    We study the effect of atomic-scale surface-lubricant interactions on nanoscale boundary-lubricated friction by considering two example surfaceshydrophilic mica and hydrophobic grapheneconfining thin layers of water in molecular dynamics simulations. We observe stick-slip dynamics for thin water films confined by mica sheets, involving periodic breaking-reforming transitions of atomic-scale capillary water bridges formed around the potassium ions of mica. However, only smooth sliding without stick-slip events is observed for water confined by graphene, as well as for thicker water layers confined by mica. Thus, our results illustrate how atomic-scale details affect the wettability of the confining surfaces and consequently control the presence or absence of stick-slip dynamics in nanoscale friction.

  6. Measurement of surface tension and viscosity by open capillary techniques

    DOEpatents

    Rye,Robert R. , Yost,Frederick G.

    1998-01-01

    An open-channel capillary is provided, having preferably a v-shaped groove in a flat wettable surface. The groove has timing marks and a source marker in which the specimen to be tested is deposited. The time of passage between the timing marks is recorded, and the ratio of surface tension .gamma. to viscosity .mu. is determined from the equation given below: ##EQU1## where h.sub.0 is the groove depth, .alpha. is the groove angle, .theta. is the liquid/solid contact angle, and t is the flow time. It has been shown by the

  7. Hydrodynamic confinement and capillary alignment of gold nanorods

    NASA Astrophysics Data System (ADS)

    Ahmad, Imtiaz; Jansen, H. Patrick; Zandvliet, Harold J. W.; Kooij, E. Stefan

    2016-01-01

    Controlling the alignment and orientation of nanorods on various surfaces poses major challenges. In this work, we investigate hydrodynamic confinement and capillary alignment of gold nanorod assembly on chemically stripe-patterned substrates. The surface patterns consist of alternating hydrophilic and hydrophobic micrometer wide stripes; a macroscopic wettability gradient enables controlling the dynamics of deposited suspension droplets. We show that drying of residual liquid on the hydrophilic stripes gives rise to spatially localized deposition and alignment of the nanorods. Moreover, a universal relation between the extent of order within the single layers of nanoparticles and the lateral dimension of the deposits is presented and discussed.

  8. Hydrodynamic confinement and capillary alignment of gold nanorods.

    PubMed

    Ahmad, Imtiaz; Jansen, H Patrick; Zandvliet, Harold J W; Kooij, E Stefan

    2016-01-15

    Controlling the alignment and orientation of nanorods on various surfaces poses major challenges. In this work, we investigate hydrodynamic confinement and capillary alignment of gold nanorod assembly on chemically stripe-patterned substrates. The surface patterns consist of alternating hydrophilic and hydrophobic micrometer wide stripes; a macroscopic wettability gradient enables controlling the dynamics of deposited suspension droplets. We show that drying of residual liquid on the hydrophilic stripes gives rise to spatially localized deposition and alignment of the nanorods. Moreover, a universal relation between the extent of order within the single layers of nanoparticles and the lateral dimension of the deposits is presented and discussed. PMID:26630013

  9. Nanoinjector for capillary electrophoresis and capillary electrochromatography.

    PubMed

    Iizuka, Eiji; Tsuda, Takao; Munesue, Motonori; Samizo, Shinichi

    2003-08-01

    A rotary valve nanoinjector was devised for use in capillary electrophoresis (CE) and capillary electrochromatography (CEC). A fused-silica capillary tip was inserted in a small through-hole in the rotor. The narrow and short capillary tip, with an inner volume of 6-24 nL, was embedded in the hole using epoxy resin. The injection volume was confirmed chromatographically by comparing the peak areas obtained with the nanoinjector to those of a conventional injector. In addition, both the rotor and stator of the injector were made of a nonconducting material, polyimide resin, to be utilized for CE and CEC. The application of the nanoinjector for CE was demonstrated. PMID:14572065

  10. IMPACT OF CAPILLARY AND BOND NUMBERS ON RELATIVE PERMEABILITY

    SciTech Connect

    Kishore K. Mohanty

    2002-09-30

    Recovery and recovery rate of oil, gas and condensates depend crucially on their relative permeability. Relative permeability in turn depends on the pore structure, wettability and flooding conditions, which can be represented by a set of dimensionless groups including capillary and bond numbers. The effect of flooding conditions on drainage relative permeabilities is not well understood and is the overall goal of this project. This project has three specific objectives: to improve the centrifuge relative permeability method, to measure capillary and bond number effects experimentally, and to develop a pore network model for multiphase flows. A centrifuge has been built that can accommodate high pressure core holders and x-ray saturation monitoring. The centrifuge core holders can operate at a pore pressure of 6.9 MPa (1000 psi) and an overburden pressure of 17 MPa (2500 psi). The effect of capillary number on residual saturation and relative permeability in drainage flow has been measured. A pore network model has been developed to study the effect of capillary numbers and viscosity ratio on drainage relative permeability. Capillary and Reynolds number dependence of gas-condensate flow has been studied during well testing. A method has been developed to estimate relative permeability parameters from gas-condensate well test data.

  11. Characterization of the Capillary Properties of Gas Diffusion Media

    NASA Astrophysics Data System (ADS)

    Gostick, Jeffrey T.; Ioannidis, Marios A.; Fowler, Michael W.; Pritzker, Mark D.

    The present generation of membrane materials used in polymer electrolyte membrane fuel cells (PEMFCs) requires high humidity to maintain sufficient proton conductivity. Mass transport through the porous electrodes, however, is most effective in dry conditions since the presence of liquid water in the pores reduces effective oxygen diffusivity to the catalytic sites. Management of these competing requirements is further complicated by the production of water inside the cell as a by-product of the cathode reaction. Maximizing fuel cell power density therefore requires effective water management techniques to prevent excessive liquid water from accumulating in the porous electrode components. Liquid water distribution and flow in the cathode gas diffusion media (GDM) of an operating PEMFC is critically affected by capillary forces. Perhaps the most widely employed technique for improving water management is to impregnate the fibrous GDM with a polymer, such as poly-tetra-fluoro-ethylene (PTFE), to coat the carbon fibers and thereby render the GDM more hydrophobic. It is thus important to understand the relationship between wettability and capillary properties of native (i.e., untreated) or PTFE-treated GDMs on the one hand and the relationship between GDM capillary properties and fuel cell performance on the other hand. Until recently, however, few experimental techniques were available to measure the capillary properties of GDMs. This chapter discusses the present understanding of the capillary properties of GDM-water-air systems and provides a critical analysis of reported experimental techniques that have recently contributed to this understanding.

  12. Multiple capillary biochemical analyzer

    DOEpatents

    Dovichi, N.J.; Zhang, J.Z.

    1995-08-08

    A multiple capillary analyzer allows detection of light from multiple capillaries with a reduced number of interfaces through which light must pass in detecting light emitted from a sample being analyzed, using a modified sheath flow cuvette. A linear or rectangular array of capillaries is introduced into a rectangular flow chamber. Sheath fluid draws individual sample streams through the cuvette. The capillaries are closely and evenly spaced and held by a transparent retainer in a fixed position in relation to an optical detection system. Collimated sample excitation radiation is applied simultaneously across the ends of the capillaries in the retainer. Light emitted from the excited sample is detected by the optical detection system. The retainer is provided by a transparent chamber having inward slanting end walls. The capillaries are wedged into the chamber. One sideways dimension of the chamber is equal to the diameter of the capillaries and one end to end dimension varies from, at the top of the chamber, slightly greater than the sum of the diameters of the capillaries to, at the bottom of the chamber, slightly smaller than the sum of the diameters of the capillaries. The optical system utilizes optic fibers to deliver light to individual photodetectors, one for each capillary tube. A filter or wavelength division demultiplexer may be used for isolating fluorescence at particular bands. 21 figs.

  13. Multiple capillary biochemical analyzer

    DOEpatents

    Dovichi, Norman J. (Edmonton, CA); Zhang, Jian Z. (Edmonton, CA)

    1995-01-01

    A multiple capillary analyzer allows detection of light from multiple capillaries with a reduced number of interfaces through which light must pass in detecting light emitted from a sample being analyzed, using a modified sheath flow cuvette. A linear or rectangular array of capillaries is introduced into a rectangular flow chamber. Sheath fluid draws individual sample streams through the cuvette. The capillaries are closely and evenly spaced and held by a transparent retainer in a fixed position in relation to an optical detection system. Collimated sample excitation radiation is applied simultaneously across the ends of the capillaries in the retainer. Light emitted from the excited sample is detected by the optical detection system. The retainer is provided by a transparent chamber having inward slanting end walls. The capillaries are wedged into the chamber. One sideways dimension of the chamber is equal to the diameter of the capillaries and one end to end dimension varies from, at the top of the chamber, slightly greater than the sum of the diameters of the capillaries to, at the bottom of the chamber, slightly smaller than the sum of the diameters of the capillaries. The optical system utilizes optic fibres to deliver light to individual photodetectors, one for each capillary tube. A filter or wavelength division demultiplexer may be used for isolating fluorescence at particular bands.

  14. Condensation heat transfer coefficient versus wettability

    NASA Astrophysics Data System (ADS)

    Roudgar, M.; De Coninck, J.

    2015-05-01

    In this paper we show how condensation on substrates can induce wetting behavior that is quite different from that of deposited or impinging drops. We describe surfaces with the same wettability in ambient conditions presenting different wetting behavior and growth of droplets in condensation. The experimental results show a rapid spread of droplets and formation of the film on the copper surface, while droplets on SU-8 surface remains on the regular shape while they grow within the time, without coalescence, as observed for Cu. Although the heat conductivity of SU-8 is much lower, due to a difference in wetting behavior, the heat transfer coefficient (h) is higher for dropwise condensation on Cu with a thin layer of SU-8 than filmwise on the bare copper.

  15. Wettability of graphene-laminated micropillar structures

    SciTech Connect

    Bong, Jihye; Seo, Keumyoung; Ju, Sanghyun E-mail: shju@kgu.ac.kr; Park, Ji-Hoon; Ahn, Joung Real E-mail: shju@kgu.ac.kr

    2014-12-21

    The wetting control of graphene is of great interest for electronic, mechanical, architectural, and bionic applications. In this study, the wettability of graphene-laminated micropillar structures was manipulated by changing the height of graphene-laminated structures and employing the trichlorosilane (HDF-S)-based self-assembly monolayer. Graphene-laminated micropillar structures with HDF-S exhibited higher hydrophobicity (contact angle of 129.5°) than pristine graphene thin film (78.8°), pristine graphene-laminated micropillar structures (97.5°), and HDF-S self-assembled graphene thin film (98.5°). Wetting states of the graphene-laminated micropillar structure with HDF-S was also examined by using a urea solution, which flowed across the surface without leaving any residues.

  16. Wettability Switching Techniques on Superhydrophobic Surfaces

    PubMed Central

    2007-01-01

    The wetting properties of superhydrophobic surfaces have generated worldwide research interest. A water drop on these surfaces forms a nearly perfect spherical pearl. Superhydrophobic materials hold considerable promise for potential applications ranging from self cleaning surfaces, completely water impermeable textiles to low cost energy displacement of liquids in lab-on-chip devices. However, the dynamic modification of the liquid droplets behavior and in particular of their wetting properties on these surfaces is still a challenging issue. In this review, after a brief overview on superhydrophobic states definition, the techniques leading to the modification of wettability behavior on superhydrophobic surfaces under specific conditions: optical, magnetic, mechanical, chemical, thermal are discussed. Finally, a focus on electrowetting is made from historical phenomenon pointed out some decades ago on classical planar hydrophobic surfaces to recent breakthrough obtained on superhydrophobic surfaces.

  17. Wettability of graphene-laminated micropillar structures

    NASA Astrophysics Data System (ADS)

    Bong, Jihye; Seo, Keumyoung; Park, Ji-Hoon; Ahn, Joung Real; Ju, Sanghyun

    2014-12-01

    The wetting control of graphene is of great interest for electronic, mechanical, architectural, and bionic applications. In this study, the wettability of graphene-laminated micropillar structures was manipulated by changing the height of graphene-laminated structures and employing the trichlorosilane (HDF-S)-based self-assembly monolayer. Graphene-laminated micropillar structures with HDF-S exhibited higher hydrophobicity (contact angle of 129.5) than pristine graphene thin film (78.8), pristine graphene-laminated micropillar structures (97.5), and HDF-S self-assembled graphene thin film (98.5). Wetting states of the graphene-laminated micropillar structure with HDF-S was also examined by using a urea solution, which flowed across the surface without leaving any residues.

  18. Molecular dynamics of wetting layer formation and forced water invasion in angular nanopores with mixed wettability

    SciTech Connect

    Sedghi, Mohammad Piri, Mohammad; Goual, Lamia

    2014-11-21

    The depletion of conventional hydrocarbon reservoirs has prompted the oil and gas industry to search for unconventional resources such as shale gas/oil reservoirs. In shale rocks, considerable amounts of hydrocarbon reside in nanoscale pore spaces. As a result, understanding the multiphase flow of wetting and non-wetting phases in nanopores is important to improve oil and gas recovery from these formations. This study was designed to investigate the threshold capillary pressure of oil and water displacements in a capillary dominated regime inside nanoscale pores using nonequilibrium molecular dynamics (NEMD) simulations. The pores have the same cross-sectional area and volume but different cross-sectional shapes. Oil and water particles were represented with a coarse grained model and the NEMD simulations were conducted by assigning external pressure on an impermeable piston. Threshold capillary pressures were determined for the drainage process (water replaced by oil) in different pores. The molecular dynamics results are in close agreements with calculations using the Mayer-Stowe-Princen (MS-P) method which has been developed on the premise of energy balance in thermodynamic equilibrium. After the drainage simulations, a change in wall particles’ wettability from water-wet to oil-wet was implemented based on the final configuration of oil and water inside the pore. Waterflooding simulations were then carried out at the threshold capillary pressure. The results show that the oil layer formed between water in the corner and in the center of the pore is not stable and collapses as the simulation continues. This is in line with the predictions from the MS-P method.

  19. Molecular dynamics of wetting layer formation and forced water invasion in angular nanopores with mixed wettability.

    PubMed

    Sedghi, Mohammad; Piri, Mohammad; Goual, Lamia

    2014-11-21

    The depletion of conventional hydrocarbon reservoirs has prompted the oil and gas industry to search for unconventional resources such as shale gas/oil reservoirs. In shale rocks, considerable amounts of hydrocarbon reside in nanoscale pore spaces. As a result, understanding the multiphase flow of wetting and non-wetting phases in nanopores is important to improve oil and gas recovery from these formations. This study was designed to investigate the threshold capillary pressure of oil and water displacements in a capillary dominated regime inside nanoscale pores using nonequilibrium molecular dynamics (NEMD) simulations. The pores have the same cross-sectional area and volume but different cross-sectional shapes. Oil and water particles were represented with a coarse grained model and the NEMD simulations were conducted by assigning external pressure on an impermeable piston. Threshold capillary pressures were determined for the drainage process (water replaced by oil) in different pores. The molecular dynamics results are in close agreements with calculations using the Mayer-Stowe-Princen (MS-P) method which has been developed on the premise of energy balance in thermodynamic equilibrium. After the drainage simulations, a change in wall particles' wettability from water-wet to oil-wet was implemented based on the final configuration of oil and water inside the pore. Waterflooding simulations were then carried out at the threshold capillary pressure. The results show that the oil layer formed between water in the corner and in the center of the pore is not stable and collapses as the simulation continues. This is in line with the predictions from the MS-P method. PMID:25416901

  20. Influence of Surface Wettability on Microbubble Formation.

    PubMed

    Wesley, Daniel J; Smith, Rachel M; Zimmerman, William B; Howse, Jonathan R

    2016-02-01

    The production and utilization of microbubbles are rapidly becoming of major importance in a number of global applications, from biofuel production to medical imaging contrast agents. Many aspects of bubble formation have been studied, with diffuser characteristics (such as pore size, pore orientation) and gas flow rate all being shown to influence the bubble formation process. However, very little attention has been paid to the influence of surface wettability of the diffuser and the detailed role it plays at the triple interface of gas-liquid-diffuser. Here, we investigate how the wettability of the diffuser surface impacts upon the dynamics of the bubble formation process and examine the effect both at the orifice and upon the bubble cloud produced as a result of the engineered wetting variations. Experimental data shown here indicate the presence of a switching point at a contact angle of ? = 90, where bubble size vastly changes. When a surface exhibits a contact angle below 90, bubbles emitted from it are considerably smaller than those emitted from a surface with an angle in excess of 90. This effect is observable over flow rates ranging from 2.5 to 60 mL min(-1) from a single pore, an array of controlled pores, and the industrially relevant and commercially available sintered metals and sintered ceramic diffusers. It is also observed for both thiol and silane modified surfaces, encompassing a range of contact angles from 10 to 110. In addition, the importance of the diffuser plate's surface topography is discussed, with elevated roughness acting to reduce the effect of surface chemistry in some instances. PMID:26754879

  1. Wettability analysis of tin-based, lead free solders

    SciTech Connect

    Vianco, P T; Hosking, F M; Rejent, J A

    1992-01-01

    The overall program is comprised of two efforts. The first effort studies the wettability of tin-based, lead free solders on two commonly used substrate materials: copper and gold-nickel plated Kovar{trademark}. The evaluation is being conducted by the meniscometer/wetting balance technique which uses the contact angle as the primary metric to quantify wettability. Information about the rate of wetting is also obtainable with this test. The second part of the program is comprised of an assessment of the solderability of actual circuit board assemblies (surface mount and through-hole). This report will describe data from the wettability analysis of lead free solders on copper.

  2. TEACHING PHYSICS: Capillary effects

    NASA Astrophysics Data System (ADS)

    Ivanov, Dragia; Petrova, Hristina

    2000-07-01

    We examine capillary tubes with a variable cross section, in which there is a column of fully wetting or fully non-wetting liquid. The direction in which the liquid moves when the tubes are placed horizontally is determined by means of Pascal's law. We promote the idea that the conical capillary tube is a hydraulic machine, whose two pistons are the liquid column's free surfaces, which have different radii. We propose a new way of demonstrating the described capillary effects by means of flat models of capillary tubes, constructed from glass plates. The demonstrations are presented in front of a large audience using an overhead projector.

  3. Water Tank with Capillary Air/Liquid Separation

    NASA Technical Reports Server (NTRS)

    Ungar, Eugene K.; Smith, Frederick; Edeen, Gregg; Almlie, Jay C.

    2010-01-01

    A bladderless water tank (see figure) has been developed that contains capillary devices that allow it to be filled and emptied, as needed, in microgravity. When filled with water, the tank shields human occupants of a spacecraft against cosmic radiation. A membrane that is permeable by air but is hydrophobic (neither wettable nor permeable by liquid water) covers one inside surface of the tank. Grooves between the surface and the membrane allow air to flow through vent holes in the surface as the tank is filled or drained. A margin of wettable surface surrounds the edges of the membrane, and all the other inside tank surfaces are also wettable. A fill/drain port is located in one corner of the tank and is covered with a hydrophilic membrane. As filling begins, water runs from the hydrophilic membrane into the corner fillets of the tank walls. Continued filling in the absence of gravity will result in a single contiguous air bubble that will be vented through the hydrophobic membrane. The bubble will be reduced in size until it becomes spherical and smaller than the tank thickness. Draining the tank reverses the process. Air is introduced through the hydrophobic membrane, and liquid continuity is maintained with the fill/drain port through the corner fillets. Even after the tank is emptied, as long as the suction pressure on the hydrophilic membrane does not exceed its bubble point, no air will be drawn into the liquid line.

  4. PWB solder wettability after simulated storage

    SciTech Connect

    Hernandez, C.L.; Hosking, F.M.

    1996-03-01

    A new solderability test method has been developed at Sandia National Laboratories that simulates the capillary flow physics of solders on circuit board surfaces. The solderability test geometry was incorporated on a circuit board prototype that was developed for a National Center for Manufacturing Sciences (NCMS) program. The work was conducted under a cooperative research and development agreement between Sandia National Laboratories, NCMS, and several PWB fabricators (AT&T, IBM, Texas Instruments, United Technologies/Hamilton Standard and Hughes Aircraft) to advance PWB interconnect technology. The test was used to investigate the effects of environmental prestressing on the solderability of printed wiring board (PWB) copper finishes. Aging was performed in a controlled chamber representing a typical indoor industrial environment. Solderability testing on as-fabricated and exposed copper samples was performed with the Sn-Pb eutectic solder at four different reflow temperatures (215, 230, 245 and 260{degrees}C). Rosin mildly activated (RMA), low solids (LS), and citric acid-based (CA) fluxes were included in the evaluation. Under baseline conditions, capillary flow was minimal at the lowest temperatures with all fluxes. Wetting increased with temperature at both baseline and prestressing conditions. Poor wetting, however, was observed at all temperatures with the LS flux. Capillary flow is effectively restored with the CA flux.

  5. Effect of rust on the wettability of steel by water

    SciTech Connect

    Lu, W.; Chung, D.D.L.

    1998-04-01

    Rust, as formed on steel by immersion of low-carbon steel in water, was found to improve the wettability of steel by water. The advancing contact angle decreased from 87{degree} to 32{degree}, and the receding contact angle decreased from 81{degree} to 29{degree}. Cleansing of steel by acetone also helped improve the wettability, but the advancing angle only decreased from 87{degree} to 73{degree}, and the receding angle only decreased from 81{degree} to 41{degree}.

  6. Wettability alteration of oil-wet carbonate by silica nanofluid.

    PubMed

    Al-Anssari, Sarmad; Barifcani, Ahmed; Wang, Shaobin; Maxim, Lebedev; Iglauer, Stefan

    2016-01-01

    Changing oil-wet surfaces toward higher water wettability is of key importance in subsurface engineering applications. This includes petroleum recovery from fractured limestone reservoirs, which are typically mixed or oil-wet, resulting in poor productivity as conventional waterflooding techniques are inefficient. A wettability change toward more water-wet would significantly improve oil displacement efficiency, and thus productivity. Another area where such a wettability shift would be highly beneficial is carbon geo-sequestration, where compressed CO2 is pumped underground for storage. It has recently been identified that more water-wet formations can store more CO2. We thus examined how silica based nanofluids can induce such a wettability shift on oil-wet and mixed-wet calcite substrates. We found that silica nanoparticles have an ability to alter the wettability of such calcite surfaces. Nanoparticle concentration and brine salinity had a significant effect on the wettability alteration efficiency, and an optimum salinity was identified, analogous to that one found for surfactant formulations. Mechanistically, most nanoparticles irreversibly adhered to the oil-wet calcite surface (as substantiated by SEM-EDS and AFM measurements). We conclude that such nanofluid formulations can be very effective as enhanced hydrocarbon recovery agents and can potentially be used for improving the efficiency of CO2 geo-storage. PMID:26414426

  7. Capillary rheometry for thermosets

    NASA Technical Reports Server (NTRS)

    Malguarnera, S. C.; Carroll, D. R.

    1982-01-01

    Capillary rheometry is effectively used with thermosets. Most important is providing a uniform temperature in the barrel. This was successfully accomplished by using a circulating hot oil system. Standard capillary rheometry methods provide the dependence of thermoset apparent viscosity on shear rate, temperature and time. Such information is very useful in evaluating resin processability and in setting preliminary fabrication conditions.

  8. Effective Wettability Measurements of CO2-Brine-Sandstone System at Different Reservoir Conditions

    NASA Astrophysics Data System (ADS)

    Al-Menhali, Ali; Krevor, Samuel

    2014-05-01

    The wetting properties of CO2-brine-rock systems will have a major impact on the management of CO2 injection processes. The wettability of a system controls the flow and trapping efficiency during the storage of CO2 in geological formations as well as the efficiency of enhanced oil recovery operations. Despite its utility in EOR and the continued development of CCS, little is currently known about the wetting properties of the CO2-brine system on reservoir rocks, and no investigations have been performed assessing the impact of these properties on CO2 flooding for CO2 storage or EOR. The wetting properties of multiphase fluid systems in porous media have major impacts on the multiphase flow properties such as the capillary pressure and relative permeability. While recent studies have shown CO2 to generally act as a non-wetting phase in siliciclastic rocks, some observations report that the contact angle varies with pressure, temperature and water salinity. Additionally, there is a wide range of reported contact angles for this system, from strongly to weakly water-wet. In the case of some minerals, intermediate wet contact angles have been observed. Uncertainty with regard to the wetting properties of CO2-brine systems is currently one of the remaining major unresolved issues with regards to reservoir management of CO2 storage. In this study, we make semi-dynamic capillary pressure measurements of supercritical CO2 and brine at reservoir conditions to observe shifts in the wetting properties. We utilize a novel core analysis technique recently developed by Pini et al in 2012 to evaluate a core-scale effective contact angle. Carbon dioxide is injected at constant flow rate into a core that is initially fully saturated with water, while maintaining a constant outlet pressure. In this scenario, the pressure drop across the core corresponds to the capillary pressure at the inlet face of the core. When compared with mercury intrusion capillary pressure measurements, core-scale effective contact angle can be determined. In addition to providing a quantitative measure of the core-averaged wetting properties, the technique allows for the observation of shifts in contact angle with changing conditions. We examine the wettability changes of the CO2-brine system in Berea sandstone with variations in reservoir conditions including supercritical, gaseous and liquid CO2injection. We evaluate wettability variation within a single rock with temperature, pressure, and salinity across a range of conditions relevant to subsurface CO2 storage. This study will include results of measurements in a Berea sandstone sample across a wide range of conditions representative of subsurface reservoirs suitable for CO2 storage (5-20 MPa, 25-90 oC, 0-5 mol kg-1). The measurement uses X-ray CT imaging in a state of the art core flooding laboratory designed to operate at high temperature, pressure, and concentrated brines.

  9. Wettability of impression materials treated with disinfectants.

    PubMed

    DeWald, J P; Nakajima, H; Schniederman, E; Okabe, T

    1992-04-01

    The purpose of this investigation was to comprehensively compare various combinations of impression materials, die stones and disinfectants so as to provide clinical guidelines for selection of materials. The effect of immersion disinfection on the wettability of five types of impression materials, polyether, light-cured polyether urethane dimethacrylate, polysulfide, hydrophilic and hydrophobic polyvinyl siloxanes, was evaluated. This evaluation was determined by contact angle measurement of two die stones on the impression materials and also by bubble formation in casts made from the same materials after disinfection. The disinfectants utilized were 0.5% sodium hypochlorite and 0.13% glutaraldehyde-phenate. There were significant interactive effects (P less than 0.02) on contact angle between stone and disinfectant, impression and disinfectant, and impression and stone. The effect of disinfection was found to vary among impression materials. Although there was a significant correlation found between contact angle and bubble formation, contact angle was not found to be a strong predictor of bubble formation in this study. For these findings, it is recommended to evaluate each disinfectant and impression material combination individually. PMID:1524745

  10. Evaluating the Influence of Pore Architecture and Initial Saturation on Wettability and Relative Permeability in Heterogeneous, Shallow-Shelf Carbonates

    SciTech Connect

    Alan P. Byrnes; Saibal Bhattacharya; John Victorine; Ken Stalder

    2007-09-30

    Thin (3-40 ft thick), heterogeneous, limestone and dolomite reservoirs, deposited in shallow-shelf environments, represent a significant fraction of the reservoirs in the U.S. midcontinent and worldwide. In Kansas, reservoirs of the Arbuckle, Mississippian, and Lansing-Kansas City formations account for over 73% of the 6.3 BBO cumulative oil produced over the last century. For these reservoirs basic petrophysical properties (e.g., porosity, absolute permeability, capillary pressure, residual oil saturation to waterflood, resistivity, and relative permeability) vary significantly horizontally, vertically, and with scale of measurement. Many of these reservoirs produce from structures of less than 30-60 ft, and being located in the capillary pressure transition zone, exhibit vertically variable initial saturations and relative permeability properties. Rather than being simpler to model because of their small size, these reservoirs challenge characterization and simulation methodology and illustrate issues that are less apparent in larger reservoirs where transition zone effects are minor and most of the reservoir is at saturations near S{sub wirr}. These issues are further augmented by the presence of variable moldic porosity and possible intermediate to mixed wettability and the influence of these on capillary pressure and relative permeability. Understanding how capillary-pressure properties change with rock lithology and, in turn, within transition zones, and how relative permeability and residual oil saturation to waterflood change through the transition zone is critical to successful reservoir management and as advanced waterflood and improved and enhanced recovery methods are planned and implemented. Major aspects of the proposed study involve a series of tasks to measure data to reveal the nature of how wettability and drainage and imbibition oil-water relative permeability change with pore architecture and initial water saturation. Focus is placed on carbonate reservoirs of widely varying moldic pore systems that represent the major of reservoirs in Kansas and are important nationally and worldwide. A goal of the project is to measure wettability, using representative oils from Kansas fields, on a wide range of moldic-porosity lithofacies that are representative of Kansas and midcontinent shallow-shelf carbonate reservoirs. This investigation will discern the relative influence of wetting and pore architecture. In the midcontinent, reservoir water saturations are frequently greater than 'irreducible' because many reservoirs are largely in the capillary transition zone. This can change the imbibition oil-water relative permeability relations. Ignoring wettability and transition-zone relative permeabilities in reservoir modeling can lead to over- and under-prediction of oil recovery and recovery rates, and less effective improved recovery management. A goal of this project is to measure drainage and imbibition oil-water relative permeabilities for a large representative range of lithofacies at differ ent initial water saturations to obtain relations that can be applied everywhere in the reservoir. The practical importance of these relative permeability and wettability models will be demonstrated by using reservoir simulation studies on theoretical/generic and actual reservoir architectures. The project further seeks to evaluate how input of these new models affects reservoir simulation results at varying scales. A principal goal is to obtain data that will allow us to create models that will show how to accurately simulate flow in the shallow-structure, complex carbonate reservoirs that lie in the transition zone. Tasks involved to meet the project objectives include collection and consolidation of available data into a publicly accessible relational digital database and collection of oil and rock samples from carbonate fields around the state (Task 1). Basic properties of these rocks and oils will be measured and used in wettability tests. Comparison will be performed between crude and synthetic oil wettability and evaluation made of how wettability is influenced by pore architecture (Task 2). Drainage and imbibition oil-water relative permeabilities will be measured on representative rock types obtained from across the state using crude and synthetic oil for a range of initial water saturations to evaluate the role that initial water saturation, wettability, and pore architecture play on relative permeability (Task 3). The new petrophysical models will be used to construct theoretical reservoir architecture models and new geomodels for two fields previously simulated using simpler models and for two new field locations in which native-state core will be obtained and analyzed (Task 4). Using the theoretical and real geomodels, simulations will both parametrically explore the influence of relative permeability differences and allow comparison with previous simulation models and results.

  11. Wettability of denture relining materials under water storage over time

    PubMed Central

    Jin, Na-Young; Lee, Ho-Rim; Lee, Heesu

    2009-01-01

    STATEMENT OF PROBLEM Poor wettability of denture relining materials may lead to retention problems and patient discomfort. PURPOSE Purpose of this study is to compare and evaluate wettability of nine denture relining materials using contact angle measurements under air and water storage over time. MATERIAL AND METHODS Nine denture relining materials were investigated in this study. Two heat-curing polymethyl-methacrylate (PMMA) denture base materials: Vertex RS, Lang, one self-curing polyethyl-methacrylate (PEMA) chairside reline resin: Rebase II, six silicone relining materials: Mucopren soft, Mucosoft, Mollosil plus, Sofreliner Touch, GC Reline Ultrasoft, Silagum automix comfort were used in this experiment. Contact angles were measured using high-resolution drop shape analysis system (DSA 10-MK2, KRUESS, Germany) under three conditions (in air after setting, 1 hour water storage, and 24 hours water storage). Nine materials were classified into three groups according to material composition (Group 1: PMMA, Group 2: PEMA, Group 3: Silicone). Mean values of contact angles were compared using independent samples t-test and one-way ANOVA, followed by a Scheffe's post hoc analysis (?= 0.01). RESULTS Contact angles of materials tested after air and water storage increased in the following order: Group 1 (PMMA), Group 2 (PEMA), Group 3 (Silicone). Heat-cured acrylic denture base resins had more wettability than silicone relining materials. Lang had the highest wettability after 24 hours of water storage. Silicone relining materials had lower wettability due to their hydrophobicity. Wettability of all denture relining materials, except Rebase II and Mollosil plus, increased after 24 hours of water storage. CONCLUSIONS Conventional heat-cured resin showed the highest wettability, therefore, it can be suggested that heat-cured acrylic resin is material of choice for denture relining materials. PMID:21165247

  12. Multiplexed capillary electrophoresis system

    DOEpatents

    Yeung, E.S.; Chang, H.T.; Fung, E.N.; Li, Q.; Lu, X.

    1996-12-10

    The invention provides a side-entry optical excitation geometry for use in a multiplexed capillary electrophoresis system. A charge-injection device is optically coupled to capillaries in the array such that the interior of a capillary is imaged onto only one pixel. In Sanger-type 4-label DNA sequencing reactions, nucleotide identification (``base calling``) is improved by using two long-pass filters to split fluorescence emission into two emission channels. A binary poly(ethyleneoxide) matrix is used in the electrophoretic separations. 19 figs.

  13. Multiplexed capillary electrophoresis system

    DOEpatents

    Yeung, E.S.; Li, Q.; Lu, X.

    1998-04-21

    The invention provides a side-entry optical excitation geometry for use in a multiplexed capillary electrophoresis system. A charge-injection device is optically coupled to capillaries in the array such that the interior of a capillary is imaged onto only one pixel. In Sanger-type 4-label DNA sequencing reactions, nucleotide identification (``base calling``) is improved by using two long-pass filters to split fluorescence emission into two emission channels. A binary poly(ethyleneoxide) matrix is used in the electrophoretic separations. 19 figs.

  14. Multiplexed capillary electrophoresis system

    DOEpatents

    Yeung, Edward S. (Ames, IA); Chang, Huan-Tsang (Silver Spring, MD); Fung, Eliza N. (Ames, IA); Li, Qingbo (Ames, IA); Lu, Xiandan (Ames, IA)

    1996-12-10

    The invention provides a side-entry optical excitation geometry for use in a multiplexed capillary electrophoresis system. A charge-injection device is optically coupled to capillaries in the array such that the interior of a capillary is imaged onto only one pixel. In Sanger-type 4-label DNA sequencing reactions, nucleotide identification ("base calling") is improved by using two long-pass filters to split fluorescence emission into two emission channels. A binary poly(ethyleneoxide) matrix is used in the electrophoretic separations.

  15. Multiplexed capillary electrophoresis system

    DOEpatents

    Yeung, Edward S. (Ames, IA); Li, Qingbo (Ames, IA); Lu, Xiandan (Ames, IA)

    1998-04-21

    The invention provides a side-entry optical excitation geometry for use in a multiplexed capillary electrophoresis system. A charge-injection device is optically coupled to capillaries in the array such that the interior of a capillary is imaged onto only one pixel. In Sanger-type 4-label DNA sequencing reactions, nucleotide identification ("base calling") is improved by using two long-pass filters to split fluorescence emission into two emission channels. A binary poly(ethyleneoxide) matrix is used in the electrophoretic separations.

  16. Switch isotropic/anisotropic wettability via dual-scale rods

    NASA Astrophysics Data System (ADS)

    He, Yang; Jiang, Chengyu; Wang, Shengkun; Ma, Zhibo; Yuan, Weizheng

    2014-10-01

    It is the first time to demonstrate the comparison of isotropic/anisotropic wettability between dual-scale micro-nano-rods and single-scale micro-rods. Inspired by the natural structures of rice leaf, a series of micro-nano-rods and micro-rods with different geometric parameters were fabricated using micro-fabrication technology. Experimental measured apparent contact angles and advancing and receding contact angles from orthogonal orientations were characterized. The difference of contact angles from orthogonal orientation on dual-scale rods was much smaller than those on single-scale rods in both static and dynamic situation. It indicated that the dual-scale micro-nano-rods showed isotropic wettability, while single-scale micro-rods showed anisotropic wettability. The switch of isotropic/anisotropic wettability could be illustrated by different wetting state and contact line moving. It offers a facial way to switch isotropic/anisotropic wettability of the surface via dual-scale or single-scale structure.

  17. Fabrication of high wettability gradient on copper substrate

    NASA Astrophysics Data System (ADS)

    Huang, Ding-Jun; Leu, Tzong-Shyng

    2013-09-01

    Copper is one of the most widely used materials in condensation heat transfer. Recently there has been great interest in improving the condensation heat transfer efficiency through copper surface modification. In this study, we describe the fabrication processes of how copper surfaces were modified to be superhydrophilic (CA ? 10) and superhydrophobic (CA > 150) by means of H2O2 immersion and fluorination with Teflon. The wettability gradient of copper surfaces with contact angles (CA) changing from superhydrophilic to superhydrophobic are also demonstrated. Unlike previous studies on gradient surfaces in which the wettability gradient is controlled either non-precisely or entirely uncontrolled, in this study, the contact angles along wettability gradient copper surfaces vary with a precisely designed gradient. It is demonstrated that a high wettability gradient copper surface can be successfully fabricated using photolithography to define the area ratios between superhydrophilic and superhydrophobic patterns within a short distance. The fabricated wettability gradient of copper surfaces is expected to be able to enhance the condensation heat transfer efficiency.

  18. Displaced capillary dies

    DOEpatents

    Kalejs, Juris P. (Wellesley, MA); Chalmers, Bruce (Falmouth, MA); Surek, Thomas (Englewood, CO)

    1982-01-01

    An asymmetrical shaped capillary die made exclusively of graphite is used to grow silicon ribbon which is capable of being made into solar cells that are more efficient than cells produced from ribbon made using a symmetrically shaped die.

  19. Displaced capillary dies

    DOEpatents

    Kalejs, Juris P. (Wellesley, MA); Chalmers, Bruce (Falmouth, MA); Surek, Thomas (Englewood, CO)

    1984-01-01

    An asymmetrical shaped capillary die made exclusively of graphite is used to grow silicon ribbon which is capable of being made into solar cells that are more efficient than cells produced from ribbon made using a symmetrically shaped die.

  20. A Comparison of Splash Erosion Behavior between Wettable and Water Repellent 'Soil' Particles

    NASA Astrophysics Data System (ADS)

    Ahn, S.; Hamlett, C. A.; Doerr, S.; Bryant, R.; Shirtcliffe, N.; McHale, G.; Newton, M.

    2011-12-01

    Wildfires remove vegetation and litter cover and expose soil surfaces to particle detachment by rain splash. This can serve as an agent of initial soil modification and erosion in the post-fire period. Splash behavior is mainly determined by the kinetic energy delivered by impacting water drops (erosivity), and the detachability (erodibility) of surface particles, affected by their size, aggregate stability and shear strength. Soil detachability may also be affected by water repellency (hydrophobicity). This soil characteristic is influenced by wildfire and may affect splash behavior by reducing capillary forces between particles. Previous work on splash behavior using cumulative drop impact reported larger ejection droplets and lower and shorter trajectories of ejections for water repellent soil compared with wettable soil (Terry and Shakesby 1993). A water film generated by delayed infiltration on water repellent soil was suggested to account for the difference. This study compares the trajectories of ejected wettable and hydrophobic model soil particles from single water drop impacts in order to isolate the effect of soil particle wettability on splash erosion behavior. Acid-washed (wettable) and hydrophobized (water repellent) glass beads used as model soil particles were held in an array within a squat cylinder of 1.5 cm diameter in the centre of a 20 cm diameter disk covered with a viscous adhesive film. A distilled water drop (20μL) was released 40 cm above the centre of the array and the resultant impact was recorded at 976 frames per second using a high speed video camera. The populations of, and distances travelled by, the particles were measured for three arrays of bead sizes within the range (180-400 μm). Three to five replications were made for each test. The trajectory of each ejected particle was traced on video frames and corrected for the actual distance and direction of travel measured from the adhesive film. The initial velocity and ejecting angle of individual particles were calculated from the equation of motion, ignoring the air resistance and in-flight evaporation. In contrast to Terry and Shakesby (1993), we observed that a single drop impact resulted mainly in dispersion (splash saltation) with few ejections of particles entrained by a water droplet (splashing), and the trajectories of ejections from water repellent particle arrays were higher than those from the hydrophilic arrays. These higher trajectories were driven by higher initial velocity for the water repellent particles, despite lower ejecting angles. This result suggests that water repellent soil is more vulnerable to initial splash detachment before a water film is generated by accumulation of rain drops. The distributions of initial velocity and ejecting angle of all particles are compared between wettable and water repellent particles and discussed in detail in this contribution. Terry JP and Shakesby RA, 1993. Earth Surface Processes and Landforms 18: 519-525. Acknowledgement: This study has been funded by Engineering and Physical Sciences Research Council of United Kingdom.

  1. Capillary discharge source

    DOEpatents

    Bender, III, Howard Albert

    2003-11-25

    Debris generation from an EUV electric discharge plasma source device can be significantly reduced or essentially eliminated by encasing the electrodes with dielectric or electrically insulating material so that the electrodes are shielded from the plasma, and additionally by providing a path for the radiation to exit wherein the electrodes are not exposed to the area where the radiation is collected. The device includes: (a) a body, which is made of an electrically insulating material, that defines a capillary bore that has a proximal end and a distal end and that defines at least one radiation exit; (b) a first electrode that defines a first channel that has a first inlet end that is connected to a source of gas and a first outlet end that is in communication with the capillary bore, wherein the first electrode is positioned at the distal end of the capillary bore; (c) a second electrode that defines a second channel that has a second inlet end that is in communication with the capillary bore and an outlet end, wherein the second electrode is positioned at the proximal end of the capillary bore; and (d) a source of electric potential that is connected across the first and second electrodes, wherein radiation generated within the capillary bore is emitted through the at least one radiation exit and wherein the first electrode and second electrode are shielded from the emitted radiation.

  2. Capillary saturation and desaturation

    NASA Astrophysics Data System (ADS)

    Hilfer, R.; Armstrong, R. T.; Berg, S.; Georgiadis, A.; Ott, H.

    2015-12-01

    Capillary desaturation experiments produce disconnected (trapped) ganglia of mesoscopic sizes intermediate between pore size and system size. Experimental evidence for interactions between these mesoscale clusters during desaturation is analyzed and discussed within the established microscopic and macroscopic laws of Newton, Young-Laplace, and Darcy. A theoretical expression for capillary number correlations is introduced that seems to have remained unnoticed. It expresses capillary desaturation curves in terms of stationary capillary pressures and relative permeabilities. The theoretical expression shows that the plateau saturation in capillary desaturation curves may in general differ from the residual nonwetting saturation defined through the saturation limit of the main hysteresis loop. Hysteresis effects as well as the difference between wetting and nonwetting fluids are introduced into the analysis of capillary desaturation experiments. The article examines experiments with different desaturation protocols and discusses the existence of a mesoscopic length scale intermediate between pore scale and sample scale. The theoretical expression is derived entirely within the existing traditional theory of two-phase flow in porous media and compared to a recent experiment.

  3. Environmental Applications of Interfacial Materials with Special Wettability.

    PubMed

    Wang, Zhangxin; Elimelech, Menachem; Lin, Shihong

    2016-03-01

    Interfacial materials with special wettability have become a burgeoning research area in materials science in the past decade. The unique surface properties of materials and interfaces generated by biomimetic approaches can be leveraged to develop effective solutions to challenging environmental problems. This critical review presents the concept, mechanisms, and fabrication techniques of interfacial materials with special wettability, and assesses the environmental applications of these materials for oil-water separation, membrane-based water purification and desalination, biofouling control, high performance vapor condensation, and atmospheric water collection. We also highlight the most promising properties of interfacial materials with special wettability that enable innovative environmental applications and discuss the practical challenges for large-scale implementation of these novel materials. PMID:26829583

  4. Impact of lipopolysaccharide coating on clay particle wettability.

    PubMed

    Chen, Gang; Zhu, Honglong

    2004-05-15

    Impact of lipopolysaccharide coating on kaolinite and Na-montmorillonite wettability was investigated. Kaolinite had greater diiodomethane contact angles, smaller water and formamide contact angles than Na-montmorillonite. After lipopolysaccharide coating, diiodomethane and formamide contact angles decreased, while water contact angles increased for both kaolinite and Na-montmorillonite. The decrease and increase in liquid contact angles after lipopolysaccharide coating were most pronounced for lipopolysaccharide extracted from Pseudomonas aeruginosa, followed by Pseudomonas fluorescens and Echerichia coli. Clay particle wettability was determined by particle surface thermodynamic properties. Both kaolinite and Na-montmorillonite exhibited a monopolar surface and the monopolarity decreased after lipopolysaccharide coating, indicating an increase in hydration or surface wetness. The origins of interactions of clay particles with water molecules were discussed and related to clay particle water wettability. PMID:15261047

  5. Water-collecting behavior of nanostructured surfaces with special wettability

    NASA Astrophysics Data System (ADS)

    Choo, Soyoung; Choi, Hak-Jong; Lee, Heon

    2015-01-01

    Dew is commonly formed even in dry regions, and we examined the suitability of surfaces with superhydrophilic patterns on a superhydrophobic background as a dew-harvesting system. Nanostructured surfaces with mixed wettability were fabricated by ZnO and TiO2 nanorods. The condensation properties were investigated by environmental scanning electron microscopy (ESEM), and the water-collecting function of the patterned surfaces in an artificial environment was confirmed. Condensation and water-collecting behavior were evaluated as a function of surface inclination angle and pattern shape. We examined the collecting efficiency among the different wettabilities at various inclination angles and observed the condensation behavior for various superhydrophilic shapes.

  6. Moisture and aging effects of solder wettability of copper surfaces

    SciTech Connect

    Hernandez, C.L.; Sorensen, N.R.; Lucero, S.J.

    1996-12-01

    Solderability is a critical property of electronic assembly that affects both manufacturing efficiency and product reliability. There is often a considerable time interval between initial fabrication of a circuit board or component and its use at the assembly level. Parts are often stored under a variety of conditions, usually not controlled. Solder wettability can soon deteriorate during storage, especially in extreme environments. This paper describes ongoing efforts at Sandia to quantify solder wettability on bare and aged Cu surfaces. In addition, organic solderability preservatives (OSPs) were applied to the bare Cu to retard solderability loss due to aging. The OSPs generally performed well, although wetting did decrease with exposure time.

  7. Fabrication of superhydrophobic polyaniline films with rapidly switchable wettability

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaoyan; Zhang, Zhaozhu; Men, Xuehu; Yang, Jin; Xu, Xianghui; Zhu, Xiaotao; Xue, Qunji

    2011-10-01

    A superhydrophobic polyaniline (PANI) film has been fabricated by using a facile one-step spraying method. The PANI was synthesized via in situ doping polymerization in the presence of perfluorooctanoic acid (PFOA) as the dopant. The water contact angle of this superhydrophobic surface reaches to 156°. Both the surface chemical compositions and morphological structures were analyzed. A granular morphology of PANI with a moderate amount of nanofibers was obtained. Moreover, a rapid surface wettability transition between superhydrophobicity and superhydrophilicity can be observed when it is doped with PFOA and de-doped with base. The mechanism for this tunable wettability has been discussed in detail.

  8. The tunable wettability in multistimuli-responsive smart graphene surfaces

    NASA Astrophysics Data System (ADS)

    Wan, Shanhong; Pu, Jibin; Zhang, Xiaoqian; Wang, Liping; Xue, Qunji

    2013-01-01

    The tunable wettability of smart graphene films onto stainless steel substrates with a multi-response to different environmental stimuli has been investigated including light irradiation, pH, electric field, and annealing temperature. Conductive graphene film exhibited the controllable transition from water-repellent to water-loving characteristic in response to different environment fields, which primarily resulted from the morpho-chemically synergistic effect as well as the restoration of electronic stucture. Based on the fundamental theories of wettability, mechanisms in switching from hydrophobicity to hydrophilicity for smart graphene surface including thermal chemistry, electrostatic, photo-induced surface chemistry, solvent, and pH methods were presented.

  9. Efficient water collection on integrative bioinspired surfaces with star-shaped wettability patterns.

    PubMed

    Bai, Hao; Wang, Lin; Ju, Jie; Sun, Ruize; Zheng, Yongmei; Jiang, Lei

    2014-08-01

    Inspired by the water-collecting strategies of desert beetles and spider silk, a novel kind of surface with star-shaped wettablity patterns has been developed. By combining both wettability and shape gradients, the as-prepared surface has gained higher efficiency in water collection compared to circle-shaped wettability patterns and uniformly superhydrophilic or superhydrophobic surfaces. PMID:24847736

  10. Capillary pressure and saturation relations for supercritical CO2 and brine in sand: High-pressure Pc(Sw) controller/meter measurements and capillary scaling predictions

    NASA Astrophysics Data System (ADS)

    Tokunaga, Tetsu K.; Wan, Jiamin; Jung, Jong-Won; Kim, Tae Wook; Kim, Yongman; Dong, Wenming

    2013-08-01

    In geologic carbon sequestration, reliable predictions of CO2 storage require understanding the capillary behavior of supercritical (sc) CO2. Given the limited availability of measurements of the capillary pressure (Pc) dependence on water saturation (Sw) with scCO2 as the displacing fluid, simulations of CO2 sequestration commonly rely on modifying more familiar air/H2O and oil/H2O Pc(Sw) relations, adjusted to account for differences in interfacial tensions. In order to test such capillary scaling-based predictions, we developed a high-pressure Pc(Sw) controller/meter, allowing accurate Pc and Sw measurements. Drainage and imbibition processes were measured on quartz sand with scCO2-brine at pressures of 8.5 and 12.0 MPa (45°C), and air-brine at 21°C and 0.1 MPa. Drainage and rewetting at intermediate Sw levels shifted to Pc values that were from 30% to 90% lower than predicted based on interfacial tension changes. Augmenting interfacial tension-based predictions with differences in independently measured contact angles from different sources led to more similar scaled Pc(Sw) relations but still did not converge onto universal drainage and imbibition curves. Equilibrium capillary trapping of the nonwetting phases was determined for Pc = 0 during rewetting. The capillary-trapped volumes for scCO2 were significantly greater than for air. Given that the experiments were all conducted on a system with well-defined pore geometry (homogeneous sand), and that scCO2-brine interfacial tensions are fairly well constrained, we conclude that the observed deviations from scaling predictions resulted from scCO2-induced decreased wettability. Wettability alteration by scCO2 makes predicting hydraulic behavior more challenging than for less reactive fluids.

  11. Gas-Filled Capillary Model

    SciTech Connect

    Steinhauer, L. C.; Kimura, W. D.

    2006-11-27

    We have developed a 1-D, quasi-steady-state numerical model for a gas-filled capillary discharge that is designed to aid in selecting the optimum capillary radius in order to guide a laser beam with the required intensity through the capillary. The model also includes the option for an external solenoid B-field around the capillary, which increases the depth of the parabolic density channel in the capillary, thereby allowing for propagation of smaller laser beam waists. The model has been used to select the parameters for gas-filled capillaries to be utilized during the Staged Electron Laser Acceleration -- Laser Wakefield (STELLA-LW) experiment.

  12. Droplet impact on a porous substrate: a capillary tube model

    NASA Astrophysics Data System (ADS)

    Ding, Hang; Theofanous, Theo

    2009-11-01

    The dynamics of impacting (spreading, penetrating) a droplet on a porous substrate, modeled by an array of capillary tubes, is studied numerically using diffuse interface methods. The absorption rate depends on the diameter ratio of the capillary tube to the droplet, wettability, and liquid properties. The flow dynamics is resolved by solving the Navier-Stokes equations and interface capturing is governed by the Cahn-Hilliard equation. Contact-angle hysteresis is included (Ding&Spelt 2008) and the stress singularity at moving contact lines is relieved using a diffuse interface model (Seppecher 1996; Jaqcmin 2000). The model is validated by studying the evolution of a droplet initially resting on a porous substrate and by comparison to drop-impact experiments involving just one capillary tube (Kogan et al 2008). Comparisons with analytical solutions and results available in the literature (e.g. Hilpert & Ben-David 2009) are presented. Through parametric simulations over relevant ranges of Reynolds and Ohnesorge numbers and contact angles, impact regime maps are derived.

  13. Capillary condenser/evaporator

    NASA Technical Reports Server (NTRS)

    Valenzuela, Javier A. (Inventor)

    2010-01-01

    A heat transfer device is disclosed for transferring heat to or from a fluid that is undergoing a phase change. The heat transfer device includes a liquid-vapor manifold in fluid communication with a capillary structure thermally connected to a heat transfer interface, all of which are disposed in a housing to contain the vapor. The liquid-vapor manifold transports liquid in a first direction and conducts vapor in a second, opposite direction. The manifold provides a distributed supply of fluid (vapor or liquid) over the surface of the capillary structure. In one embodiment, the manifold has a fractal structure including one or more layers, each layer having one or more conduits for transporting liquid and one or more openings for conducting vapor. Adjacent layers have an increasing number of openings with decreasing area, and an increasing number of conduits with decreasing cross-sectional area, moving in a direction toward the capillary structure.

  14. Capillary stretching of fibers

    NASA Astrophysics Data System (ADS)

    Duprat, C.; Protiere, S.

    2015-09-01

    We study the interaction of a finite volume of liquid with two parallel thin flexible fibers. A tension along the fibers is imposed and may be varied. We report two morphologies, i.e. two types of wet adhesion: a weak capillary adhesion, where a liquid drop bridges the fibers, and a strong elastocapillary adhesion where the liquid is spread between two collapsed fibers. We show that geometry, capillarity and stretching are the key parameters at play. We describe the collapse and detachment of the fibers as a function of two nondimensional parameters, arising from the geometry of the system and a balance between capillary and stretching energies. In addition, we show that the morphology, thus the capillary adhesion, can be controlled by changing the tension within the fibers.

  15. Wettability of Nafion and Nafion/Vulcan carbon composite films.

    PubMed

    Li, Xiaoan; Feng, Fangxia; Zhang, Ke; Ye, Siyu; Kwok, Daniel Y; Birss, Viola

    2012-04-24

    The wettability of the Pt/carbon/Nafion catalyst layer in proton exchange membrane fuel cells is critical to their performance and durability, especially the cathode, as water is needed for the transport of protons to the active sites and is also involved in deleterious Pt nanoparticle dissolution and carbon corrosion. Therefore, the focus of this work has been on the first-time use of the water droplet impacting method to determine the wettability of 100% Nafion films, as a benchmark, and then of Vulcan carbon (VC)/Nafion composite films, both deposited by spin-coating in the Pt-free state. Pure Nafion films, shown by SEM analysis to have a nanochanneled structure, are initially hydrophobic but become hydrophilic as the water droplet spreads, likely due to reorientation of the sulfonic acid groups toward water. The wettability of VC/Nafion composite films depends significantly on the VC/Nafion mass ratios, even though Nafion is believed to be preferentially oriented (sulfonate groups toward VC) in all cases. At low VC contents, a significant water droplet contact angle hysteresis is seen, similar to pure Nafion films, while at higher VC contents (>30%), the films become hydrophobic, also exhibiting superhydrophobicity, with surface roughness playing a significant role. At >80% VC, the surfaces become wettable again as there is insufficient Nafion loading present to fully cover the carbon surface, allowing the calculation of the Nafion:carbon ratio required for a full coverage of carbon by Nafion. PMID:22475507

  16. Dynamic wettability of pHEMA-based hydrogel contact lenses.

    PubMed

    Maldonado-Codina, Carole; Efron, Nathan

    2006-07-01

    Standard methods of contact angle analysis include sessile drop, captive bubble and Wilhelmy plate techniques; however, these methodologies are not particularly well suited for assessing the wettability of the surfaces of formed hydrogel contact lenses. This paper describes two methodologies that are adaptations of previously described techniques. The maximum adherent force method is an adaptation of the dynamic Wilhelmy plate technique that allows the assessment of whole, finished contact lenses. The dynamic photographic method allows the simultaneous assessment of the front and back surfaces of strip samples for the assessment of advancing and receding contact angles. Lenses investigated were made from polyhydroxyethyl methacrylate, hydroxyethyl methacrylate/methacrylic acid and hydroxyethyl methacrylate/glycerol methacrylate. The lenses were manufactured by lathing, spin-casting or cast-moulding techniques. Overall, both techniques demonstrated few differences between the wettability of different lens materials and no differences between materials of the 'same' lens type but manufactured by different methods. These findings are consistent with the results of clinical studies, which have shown little difference between contact lens surface wettability in vivo, which may be due to the apparent natural surface wettability-enhancing properties of the pre-lens tear film. PMID:16792741

  17. INFILTRATION OF PCE IN A SYSTEM CONTAINING SPATIAL WETTABILITY VARIATIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A two-dimensional infiltration experiment was conducted to investigate and quantify the effect of spatial wettability variations on DNAPL migration and entrapment in saturated sands. Visual observations of tetrachloroethylene (PCE) infiltration show that organic-wet sand lenses act as very effective...

  18. Directional liquid spreading over chemically defined radial wettability gradients.

    PubMed

    Bliznyuk, Olesya; Seddon, James R T; Veligura, Vasilisa; Kooij, E Stefan; Zandvliet, Harold J W; Poelsema, Bene

    2012-08-01

    We investigate the motion of liquid droplets on chemically defined radial wettability gradients. The patterns consist of hydrophobic fluorinated self-assembled monolayers (SAMs) on oxidized silicon substrates. The design comprises a central hydrophobic circle of unpatterned SAMs surrounded by annular regions of radially oriented stripes of alternating wettability, i.e., hydrophilic and hydrophobic. Variation in the relative width of the stripes allows control over the macroscopic wettability. When a droplet is deposited in the middle, it will start to move over to the radially defined wettability gradient, away from the center because of the increasing relative surface area of hydrophilic matter for larger radii in the pattern. The focus of this article is on a qualitative description of the characteristic motion on such types of anisotropic patterns. The influence of design parameters such as pattern dimensions, steepness of the gradient, and connection between different areas on the behavior of the liquid are analyzed and discussed in terms of advancing and receding contact lines, contact angles, spatial extent, and overall velocity of the motion. PMID:22839421

  19. Wettability investigating on the wet etching textured multicrystalline silicon wafer

    NASA Astrophysics Data System (ADS)

    Liu, Xiangju; Niu, Yuchao; Zhai, Tongguang; Ma, Yuying; Zhen, Yongtai; Ma, Xiaoyu; Gao, Ying

    2016-02-01

    In order to investigate the wettability properties of multicrystalline silicon (mc-Si), the different surface structures were fabricated on the as-cut p-type multi-wire slurry sawn mc-Si wafers, such as as-cut, polished and etched in various acid solutions. The contact angles and the XRD spectra of these samples were measured. It was noted that both the surface structures and the use of surfactant, such as Tween 80, made a stronger effect on wettability of the Si wafer. Due to the lipophilic groups of Tween 80 combined with the Si atoms while the hydrophilic groups of it were outward, a lipophilic surface of Si changed into a hydrophilic one and the rougher the surface, the stronger the hydrophily. Thus, it is feasible to add an appropriate surfactant into the etching solution during black-Si wafer fabrication for solar cells. In addition, different crystal plains of Si had different dangling bond density, so that their surface energies were different. A surface with higher surface energy could attract more water atoms and its wettability was better. However, the effect of crystal plain on the surface wettability was much weaker than surface morphology.

  20. Autoclaving as a mean of modifying the soil wettability characteristics

    NASA Astrophysics Data System (ADS)

    Urbanek, Emilia; Bodi, Merche; Shakesby, Rick; Doerr, Stefan

    2010-05-01

    Studies of soil water repellency have often attempted to isolate its hydrological impact by comparing responses of wettable and water repellent soils. It is, however, almost impossible to identify natural wettable and water repellent soils that are otherwise fully comparable. Furthermore no established methodology exists that allows changing a soil from wettable to water repellent (or vice versa) without affecting its chemical composition. Approaches used for rendering wettable soil (or sands) water repellent involve coating particles with hydrophobic or commercial water repellent spray. Heating soil to temperatures >300 °C has been used to eliminate existing water repellency from samples, but this can permanently alter the composition of organic matter. Here we report on a new technique for rendering wettable soil water repellent involving autoclaving. Autoclaving is commonly applied in medicine and biology for sterilization. It uses moist heat and pressure to destroy the bacteria, viruses and fungi. The same method has also been used in soil ecology studies for selective removal of certain micro-organisms. In our study, soils at various moisture contents were autoclaved in sealed bags for 1hr at 121°C. The soils became water repellent and the degree of water repellency was found to be dependent on the original soil moisture content and the soil wettability remained unchanged even with further drying of the soil up to 105°C. No changes in soil wettability were found after autoclaving very dry or wet soils. Only at certain intermediate water contents was the soil able to switch to a hydrophobic state. We suspect that the changes occurring during the autoclaving involve molecular orientation of hydrophobic and hydrophilic groups of soil organic matter, and moist heat and pressure cause the hydrophobic groups to be directed towards the outside of the soil particles which consequently repels water. Treatment of soil in this way presents a simple, inexpensive method of making a soil hydrophobic without changing its chemical composition. This has considerable potential for controlled experiments requiring both soils that differ only in terms of their degree of hydrophobicity.

  1. Microbial enhanced oil recovery and wettability research program

    SciTech Connect

    Thomas, C.P.; Bala, G.A.; Duvall, M.L.

    1991-07-01

    This report covers research results for the microbial enhanced oil recovery (MEOR) and wettability research program conducted by EG G Idaho, Inc. at the Idaho National Engineering Laboratory (INEL). The isolation and characterization of microbial species collected from various locations including target oil field environments is underway to develop more effective oil recovery systems for specific applications. The wettability research is a multi-year collaborative effort with the New Mexico Petroleum Recovery Research Center (NMPRRC), to evaluate reservoir wettability and its effects on oil recovery. Results from the wettability research will be applied to determine if alteration of wettability is a significant contributing mechanism for MEOR systems. Eight facultatively anaerobic surfactant producing isolates able to function in the reservoir conditions of the Minnelusa A Sands of the Powder River Basin in Wyoming were isolated from naturally occurring oil-laden environments. Isolates were characterized according to morphology, thermostability, halotolerance, growth substrates, affinity to crude oil/brine interfaces, degradative effects on crude oils, and biochemical profiles. Research at the INEL has focused on the elucidation of microbial mechanisms by which crude oil may be recovered from a reservoir and the chemical and physical properties of the reservoir that may impact the effectiveness of MEOR. Bacillus licheniformis JF-2 (ATCC 39307) has been used as a benchmark organism to quantify MEOR of medium weight crude oils (17.5 to 38.1{degrees}API) the capacity for oil recovery of Bacillus licheniformis JF-2 utilizing a sucrose-based nutrient has been elucidated using Berea sandstone cores. Spacial distribution of cells after microbial flooding has been analyzed with scanning electron microscopy. Also the effect of microbial surfactants on the interfacial tensions (IFT) of aqueous/crude oil systems has been measured. 87 refs., 60 figs., 15 tabs.

  2. Wettability changes in polyether impression materials subjected to immersion disinfection

    PubMed Central

    Shetty, Shweta; Kamat, Giridhar; Shetty, Rajesh

    2013-01-01

    Background: Disinfection of impression materials prevents cross-contamination; however, the disinfectants may alter the wettability property. The purpose of this investigation was to evaluate the wettability changes of polyether impression material after immersing in four different chemical disinfectant solutions for a period of 10 min and 30 min, respectively. Materials and Methods: A total of 45 samples of polyether dental impression material (Impregum soft, 3MESPE, St. Paul, MN, USA) were randomly divided into nine groups with five specimens each. Each specimen was disc shaped, flat of 32 mm diameter and 3 mm thickness. The samples were immersed in four disinfectant solutions: 2% Glutaraldehyde, 5% sodium hypochlorite, 0.05% iodophor, and 5.25% phenol for 10 min and 30 min, respectively. The control was without disinfection. Wettability of the samples was assessed by measuring the contact angle by using the Telescopic Goniometer. Data were subjected to analysis of variance (Fisher's test) and Tukey's post hoc test for multiple comparisons at 5% level of significance. Results: The contact angle of 20.21 0.22 were recorded in the control samples. After 10 min, the samples that were immersed in 5% sodium hypochlorite and 5.25% phenol showed significant statistical increase in the contact angle as compared to the control (P < 0.001). After 30 min of disinfection, only the samples immersed in 0.05% iodophor showed there were no significant changes in the contact angle, whereas the other disinfectants significantly increased the contact angle and decreased the wettability of the polyether material. Conclusion: Within the limitations of the study, 2% glutaraldehyde proved safe for 10 min of immersion disinfection while 0.05% iodophor holds promise as an effective disinfectant without affecting the wettability of the material. PMID:24130593

  3. Experimental study of heterogeneity-induced capillary trapping in the context of leakage from geologic carbon sequestration sites

    NASA Astrophysics Data System (ADS)

    Liang, B.; Clarens, A. F.

    2014-12-01

    Leakage of CO2 from geologic carbon sequestration sites could undermine the long-term goal of reducing emissions to the atmosphere. Despite this, leakage processes, especially the vertical transport of gases through geologic formations overlaying target repositories, are poorly characterized. The goal of this work was to experimentally assess how sub-basin scale heterogeneity in overlaying formations could reduce CO2 leakage. High-pressure columns packed with sand and glass beads of different sizes were used to create a capillary barrier, which is an analog of low-permeability inter-beds. Transport of the resulting plume was recorded in real time using electrical resistivity. The effect of pressure, temperature, permeability, surface wettability, and CO2 flow rate were all assessed. Real-time monitoring and quantification of CO2 saturation suggests that capillary heterogeneity trapping is primarily controlled by permeability contrast, pressure, temperature and water/CO2 wettability on mineral surfaces. The amount of trapping was considerably enhanced when permeability contrasted increased, showing a good agreement with equilibrium capillary pressure - saturation analysis in the literature. Temperature and pressure controlled experiments demonstrated the sensitivity of capillary trapping to geothermal and pressure gradient. Wettability alterations also increased initial trapping when more CO2-philic materials is presented and a much greater increase in residual trapping (defined as 10 pore volume water re-imbibition). Variation of leakage rate was not shown to result in significant difference in the overall saturation values, but the stability of the trapped plume was reduced at high CO2 injection rates. These results suggest that local capillary trapping could contribute to secondary trapping and slow the buoyancy-driven rise of CO2. These measurements could have important implications for minimizing risk associated with leakage from carbon sequestration sites.

  4. Investigating wettability alteration during MEOR process, a micro/macro scale analysis.

    PubMed

    Karimi, Mahvash; Mahmoodi, Maziyar; Niazi, Ali; Al-Wahaibi, Yahya; Ayatollahi, Shahab

    2012-06-15

    Wettability alteration is considered to be one of the important mechanisms that lead to increased oil recovery during microbial enhanced oil recovery (MEOR) processes. Changes in wettability will greatly influence the petrophysical properties of the reservoir rocks and determine the location, flow and distribution of different fluids inside the porous media. Understanding the active mechanisms of surface wettability changes by the bacteria would help to optimize the condition for more oil recovery. As the mechanisms behind wettability alteration are still poorly understood, the objective of this study is to investigate the wettability alteration at pore scale and find the most effective mechanism of wettability changes in different cases. The experiments were performed on different substrates at fresh condition or aged in crude oil to mimic various wetting conditions. Using an Enterobacter cloacae strain, the influence of bacterial metabolites, bacterial adhesion and bacterial solution with two different carbon sources on wettability were determined for different aging periods. Contact angle measurements were used to quantify the wettability alteration of the solid surfaces. Atomic force microscopy (AFM) experiments were also utilized to combine the macroscopic measurements of wettability with the microscopic study of the surface changes. It was found that the surface wettability could vary from neutral- or oil-wet to water-wet state. Bacterial adhesion and biofilm formation seems to be the dominant mechanism of wettability alteration. The aged glass surfaces regained their initial water wetness where the bacteria could remove the polar and asphaltene compounds from them. PMID:22445747

  5. Underwater Spontaneous Pumpless Transportation of Nonpolar Organic Liquids on Extreme Wettability Patterns.

    PubMed

    Huang, Shuai; Song, Jinlong; Lu, Yao; Chen, Faze; Zheng, Huanxi; Yang, Xiaolong; Liu, Xin; Sun, Jing; Carmalt, Claire J; Parkin, Ivan P; Xu, Wenji

    2016-02-10

    Spontaneous pumpless transportation (SPT) of liquids has generated tremendous demands in microfluidic systems and advanced devices. However, the transportation of nonpolar organic liquids on open platforms underwater remains a challenge because most existing SPT systems are only designed for use in air. Here, we report a surface-tension-driven SPT system to transport various nonpolar organic liquids using underwater extreme wettability patterns. The patterns were fabricated with a wedge-shaped superoleophilic track on a superoleophobic background by combining CuCl2 etching, stearic acid modification, and mask-based nitrogen cold plasma treatment. Three types of underwater SPT processes-horizontal transport, tilted transport, and directional transport-were studied experimentally and theoretically. For horizontal SPT and tilted SPT, the capillary force was the main driving force, which depended on the wedge angle of the superoleophilic track. The excellent transportation ability of horizontal SPT of underwater liquid droplets was obtained at a wedge angle of 3-5°. The maximum moving height of organic liquids on the tilted SPT transport was obtained at an angle of 8°. For directional SPT, organic liquids did not drop off in the moving process because of the constraint imposed by surface tension, resulting in the sustained directional transport with long distances and complex trajectories. PMID:26785602

  6. Numerical study of drop motion on a surface with stepwise wettability gradient and contact angle hysteresis

    NASA Astrophysics Data System (ADS)

    Huang, Jun-Jie; Huang, Haibo; Wang, Xinzhu

    2014-06-01

    In this work, the motion of a two-dimensional drop on a surface with stepwise wettability gradient (WG) is studied numerically by a hybrid lattice-Boltzmann finite-difference method. We incorporate the geometric wetting boundary condition that allows accurate implementation of a contact angle hysteresis (CAH) model. The method is first validated through a series of tests that check different constituents of the numerical model. Then, simulations of a drop on a wall with given stepwise WG are performed under different conditions. The effects of the Reynolds number, the viscosity ratio, the WG, as well as the CAH on the drop motion are investigated in detail. It was discovered that the shape of the drop in steady motion may be fitted by two arcs that give two apparent contact angles, which are related to the respective contact line velocities and the relevant contact angles (that specify the WG and CAH) through the relation derived by Cox ["The dynamics of the spreading of liquids on a solid surface. Part 1. viscous flow," J. Fluid Mech. 168, 169-194 (1986)] if the slip length in simulation is defined according to Yue et al. ["Sharp-interface limit of the Cahn-Hilliard model for moving contact lines," J. Fluid Mech. 645, 279-294 (2010)]. It was also found that the steady capillary number of the drop is significantly affected by the viscosity ratio, the magnitudes of the WG, and the CAH, whereas it almost shows no dependence on the Reynolds number.

  7. Retractable capillary doser

    NASA Astrophysics Data System (ADS)

    Fowler, G. L.; Panitz, J. A.

    1984-09-01

    A retractable capillary doser is described which can place a reproducible coverage of molecules on a substrate in an ultrahigh-vacuum environment. An integral valve assembly controls the flow of molecules from the doser volume to the substrate. Automatic operation is achieved by controlling the valve and the position of the doser orifice from a commercial IEEE interface.

  8. An improved capillary rheometer

    NASA Technical Reports Server (NTRS)

    Feinstein, S. P.

    1980-01-01

    Capillary rheometer incorporates cone-tipped preheated piston to compress plastized coal sample through narrow tube. Applied force is proportional to viscosity and is recorded on separate instrument. Samples are heated rapidly due to large area of cone surface. Device, primarily applied in designing efficient equipment for feeding coal into combustion chamber, may be readily used in other viscosity studies.

  9. Capillary tube wetting induced by particles: towards armoured bubbles tailoring.

    PubMed

    Zoueshtiagh, Farzam; Baudoin, Michael; Guerrin, David

    2014-12-21

    In this paper, we report on the strongly modified dynamics of a liquid finger pushed inside a capillary tube, when partially wettable particles are lying on the walls. Particles promote the appearance of new regimes and enable the tailored synthesis of bubbles encapsulated in a monolayer of particles (so-called "armoured bubbles"). This remarkable behavior arises due to the collection of particles at the air-liquid interface, which modify the global energy balance and stabilize the interface. Armoured-bubbles are of primary interest in industrial processes since they display increased stability, interfacial rigidity and can even sustain non-spherical shapes. This work opens perspective for a low cost bubbles-on-demand technology enabling the synthesis of armoured bubbles with specific sizes, shapes and composition. PMID:25271805

  10. LED-controlled tuning of ZnO nanowires’ wettability for biosensing applications

    PubMed Central

    Bhavsar, Kaushalkumar; Ross, Duncan; Prabhu, Radhakrishna; Pollard, Pat

    2015-01-01

    Background Wettability is an important property of solid materials which can be controlled by surface energy. Dynamic control over the surface wettability is of great importance for biosensing applications. Zinc oxide (ZnO) is a biocompatible material suitable for biosensors and microfluidic devices. Nanowires of ZnO tend to show a hydrophobic nature which decelerates the adhesion or adsorption of biomolecules on the surface and, therefore, limits their application. Methods Surface wettability of the ZnO nanowires can be tuned using light irradiation. However, the control over wettability using light-emitting diodes (LEDs) and the role of wavelength in controlling the wettability of ZnO nanowires are unclear. This is the first report on LED-based wettability control of nanowires, and it includes investigations on tuning the desired wettability of ZnO nanowires using LEDs as a controlling tool. Results The investigations on spectral properties of the LED emission on ZnO nanowires’ wettability have shown strong dependency on the spectral overlap of LED emission on ZnO absorption spectra. Results indicate that LEDs offer an advanced control on dynamically tuning the wettability of ZnO nanowires. Conclusion The spectral investigations have provided significant insight into the role of irradiating wavelength of light and irradiation time on the surface wettability of ZnO nanowires. This process is suitable to realize on chip based integrated sensors and has huge potential for eco-friendly biosensing and environmental sensing applications. PMID:25855065

  11. A surface with superoleophilic-to-superoleophobic wettability gradient.

    PubMed

    Zhang, Guangyu; Zhang, Xin; Li, Meng; Su, Zhaohui

    2014-02-12

    A strategy combining polyelectrolyte multilayer (PEM) deposition and counterion exchange was developed to fabricate wettability gradient surfaces on rough aluminum with wetting characters continuously varied from superoleophilic to superoleophobic. Counterion exchange kinetics was adopted as a means to tailor the surface chemical composition spatially, with the gradient ultimately reflecting position-dependent immersion time during the dipping of substrate in salt solution. Wettability depended on the identity and concentration of the counterion in the outermost PEM layer. Gradients could be erased and rewritten through the exchange of counterions, and the gradient's wetting character was evaluated by measuring both water and oil contact angles. The surface chemical composition gradient was further investigated by X-ray photoelectron spectroscopy. PMID:24417401

  12. Nanosecond laser texturing of aluminium for control of wettability

    NASA Astrophysics Data System (ADS)

    Sharp, Martin C.; Rosowski, Adam P.; French, Paul W.

    2015-07-01

    There is increasing interest in the use of lasers to modify the wettability of surfaces. Here we report on the use of a 20W nS pulsed IR fibre laser to create strong hydrophobicity on the surface of aluminium sheets. This is unexpected, hydrophobicity is usually associated solely with femto- or pico- second laser processing. At a 20W average power level the area coverage rate is too small for many industrial applications. Further trials using a 800W DPSS laser are described and the ability of this system to change surface wettability at a much higher production rate are indicated. There is little reported literature on surface texturing at higher average power levels. Indications of the productivity, or surface coverage rate, are given.

  13. The wettability of fluoropolymer surfaces: influence of surface dipoles.

    PubMed

    Lee, Sangwha; Park, Joon-Seo; Lee, T Randall

    2008-05-01

    The wettabilities of fluorinated polymers were evaluated using a series of contacting probe liquids ranging in nature from nonpolar aprotic to polar aprotic to polar protic. Fully fluorinated polymers were wet less than partially fluorinated polymers, highlighting the weak dispersive interactions of fluorocarbons. For partially fluorinated polymers, the interactions between the distributed dipoles along the polymer backbone and the dipoles of the contacting liquids were evaluated using both polar and nonpolar probe liquids. The results demonstrate that the surface dipoles of the fluoropolymers generated by substituting fluorine atoms with hydrogen or chlorine atoms can strongly interact with polar contacting liquids. The wettabilities of the partially fluorinated polymers were enhanced by increasing the density of dipoles across the surfaces and by introducing differentially distributed dipoles. PMID:18393484

  14. Evaluation of Reservoir Wettability and its Effect on Oil Recovery

    SciTech Connect

    Jill S. Buckley

    1998-06-12

    This project has three main goals. The first is to achieve improved understanding of the surface and interfacial properties of crude oils and their interactions with mineral surfaces. The second goal is to apply the results of surface studies to improved predictions of oil production in laboratory experiments. Finally, we aim to use the results of this research to recommend ways to improve oil recovery by waterflooding. In order to achieve these goals, the mechanisms of wetting alteration must be explained. We propose a methodology for studying those mechanisms on mineral surfaces, then applying the results to prediction and observation of wetting alteration in porous media. Improved understanding of the underlying mechanisms will show when and how wettability in the reservoir can be altered and under what circumstances that alteration would be beneficial in terms of increased production of oil. In the work reported this quarter, crude oil interactions with Berea sandstone have been used to prepare cores with mixed wettability.

  15. Capillary Isoelectric Focusing

    NASA Astrophysics Data System (ADS)

    Markuszewski, Micha? J.; Bujak, Renata; Daghir, Emilia

    Capillary isoelectric focusing (CIEF) is a widespread technique for the analysis of peptides and proteins in biological samples. CIEF is used to separate mixtures of compounds on the basis of differences in their isoelectric point. Aspects of sample preparation, capillary selection, zone mobilization procedures as well as various detection modes used have been described and discussed. Moreover CIEF, coupled to various types of detection techniques (MALDI or LIF), has increasingly been applied to the analysis of variety different high-molecular compounds. CIEF is considered as a highly specific analytical method which may be routinely used in the separation of rare hemoglobin variants. In addition, the application of CIEF in proteomic field have been discussed on the examples of analyses of glycoproteins and immunoglobins due to the meaning in clinical diagnostic.

  16. Nonlinear Gravity and Capillary-Gravity Waves

    NASA Astrophysics Data System (ADS)

    Dias, Frdric; Kharif, Christian

    1999-01-01

    This review deals primarily with the bifurcation, stability, and evolution of gravity and capillary-gravity waves. Recent results on the bifurcation of various types of capillary-gravity waves, including two-dimensional solitary waves at the minimum of the dispersion curve, are reviewed. A survey of various mechanisms (including the most recent ones) to explain the frequency downshift phenomenon is provided. Recent significant results are given on "horseshoe" patterns, which are three-dimensional structures observable on the sea surface under the action of wind or in wave tank experiments. The so-called short-crested waves are then discussed. Finally, the importance of surface tension effects on steep waves is studied.

  17. Comparison of capillary pressure relationships of organic liquid water systems containing an organic acid or base

    NASA Astrophysics Data System (ADS)

    Lord, D. L.; Demond, A. H.; Hayes, K. F.

    2005-04-01

    The presence of surface-active solutes such as organic acids and bases may have a profound influence on the transport of organic liquid contaminants through their impact on the constitutive relationship of capillary pressure vs. saturation. This relationship is a function of the interfacial tension and wettability of the system, which, in turn, depend on the pH and the concentration of organic acids and bases that are present. This study examines the impact of pH and the concentration on the interfacial tension, contact angle, and capillary pressure of systems consisting of tetrachloroethylene, water, and quartz containing either octanoic acid or dodecylamine. In general, the ionic form of the solute tended to remain in the aqueous phase and reduced the capillary pressure through its impact on the interfacial tension and contact angle; on the other hand, the neutral form of the solute partitioned into the organic liquid phase and had a lesser impact on the capillary pressure for the same total mass of solute. A comparison of these data with data generated in previous research in similar systems where o-xylene was the organic liquid showed that the trends are analogous. Thus, the behavior of these two solvent systems seems to be driven primarily by the aqueous phase speciation of the solute, and the differences between the capillary pressure relationships for the two systems could be attributed to the pure system interfacial tension.

  18. Soil Surface Composition Effects on the Wettability of Aquifer Materials

    NASA Astrophysics Data System (ADS)

    Ryder, J. L.; Demond, A. H.

    2004-05-01

    The wettability of subsurface porous media is critical for determining the distribution of non-aqueous phase liquids. Variations in the wettability of subsurface materials are generally attributed to sorption of hydrophobic contaminants. However, naturally occurring carbonaceous materials may influence the wettability as well. A series of seven soil materials were selected to determine the effect of organic carbon surfaces on soil wetting behavior. The materials represent organic carbon containing surfaces that may be found in soils from young humic matter to mature coal and shale kerogen. Measurements of organic liquid-water contact angle against cut rock faces reveal that surface composition alters the contact angle from the completely water wetted condition of quartz in the case of the mature carbon materials (Lachine Shale, Garfield Shale, Waynesburg Coal, and Plumbago Mineral Carbon). An examination of the soil elemental composition confirms that the bulk elemental composition of each material is separated on a plot of hydrogen to carbon versus oxygen to carbon ratios. The functional groups present at the surface of the soil materials were obtained with Fourier Transform Infrared Spectroscopy (FT-IR) analysis and indicate that the presence of oxygen containing surface functional groups is positively correlated with increased organic-liquid wetting. This study demonstrates that even in the absence of sorbing contaminants the subsurface is fractionally water-wet. This finding may help explain why subsurface distributions of non aqueous phase liquids can vary from those determined with laboratory sands.

  19. Bio-inspired electrospun micro/nanofibers with special wettability.

    PubMed

    Baji, Avinash; Abtahi, Mojtaba; Ramakrishna, Seeram

    2014-07-01

    Inspired by the extreme wetting states displayed by the natural materials, various techniques have been widely investigated to fabricate superhydrophobic and superhydrophilic surfaces. Electrospinning has gained huge amount of interest as fibers with suitable combination of surface chemistry and surface roughness can be easily obtained. This study provides a comprehensive overview of the progress that has been made on electrospun fibers that display superhydrophobicity, superhydrophilicity or a combination of both. The article discusses various modification techniques that can be implemented to obtain fibers with surface heterogeneity for improving its hydrophobicity or hydrophilicity. Both nanometer size of the fibers and secondary nanoscale structures ensure that the fibers have suitable surface topography to exhibit extreme wetting states. Additionally, for the first time, we critically review and identify the role of intrinsic structures such as crystallinity and chain orientation on the wettability of the fibers. We highlight some new emerging application areas that are being explored using superhydrophobic and superhydrophilic fibers. Further, methods for fabricating smart materials with special wettability are also discussed. Such fibers with special wettability show tremendous promise for water harvesting, unidirectional water collection and oil-water filtration applications. PMID:24757946

  20. Patterned wettability of oil and water in porous media.

    PubMed

    Kumar, Munish; Fogden, Andrew

    2010-03-16

    The microscopic wettability state of porous media, based on glass bead packings, after crude oil drainage of brine was investigated using X-ray micro-CT, white-light profilometry, and electron microscopy. Tomography revealed that the bulk residual brine occupied around 10% of void space, located in smaller pores and as pendular rings around bead contacts, in agreement with numerical simulations of drainage. The bead packing contained planar slabs of mica, quartz, and oxidized silicon wafer, which after flushing and disassembly of the pack allowed analysis of their wettability alteration due to deposition of asphaltenes from the crude oil. These substrates exhibited an overall pattern of rings with clean interiors, matching the brine pendular ring size inferred from experimental and simulated drainage, and asphaltene deposition in their exteriors, verifying the mixed wet model of oil reservoir wettability. The extent of asphaltene intrusion into ring interiors and completeness of asphaltene coverage of exteriors both increased with overall deposition tendency for the brine composition. The observed dependence on NaCl concentration and pH was consistent with expectations from DLVO and non-DLVO interactions governing brine thin film rupture and subsequent asphaltene deposition. PMID:19916532

  1. Surface morphology and wettability of sandblasted PEEK and its composites.

    PubMed

    Ourahmoune, R; Salvia, M; Mathia, T G; Mesrati, N

    2014-01-01

    PolyEtherEtherKetone (PEEK) is an advanced high-performance thermoplastic polymer, and its composites are used extensively in the aeronautical industry. This paper presents an experimental approach to determine the role of sandblasting treatment on surface morphology modifications of PEEK and its composites, with the aim of developing a topographic characterization in order to propose pertinent parameters that correlate with contact angles from wettability measurement. Sandblasting (fine abrasive particle projection) was selected as the surface treatment, in order to obtain various morphologically quasi-isotropic surfaces. Two surface metrological approaches to topographical characterization were used to correlate the wettability behavior with the surface roughness parameters, the first based on 2D profile analysis and the second on 3D topography analysis. Two different unreinforced grades of PEEK and four composites: discontinuous carbon fiber or glass fiber-reinforced, oriented, and unoriented, were studied. The experimental results indicated the sandblasting process duration necessary to reach a morphological steady state. It was stated that one of the pertinent parameters is the mean slope of roughness motif in 2D profile characterization, as confirmed by previous findings for anisotropic morphologies. However, for all cases, a new topographic parameter Sr , combining the surface amplitude and the summit density distribution, is proposed as a factor well-correlated with wettability characteristics. PMID:23553954

  2. Automated Parallel Capillary Electrophoretic System

    DOEpatents

    Li, Qingbo (State College, PA); Kane, Thomas E. (State College, PA); Liu, Changsheng (State College, PA); Sonnenschein, Bernard (Brooklyn, NY); Sharer, Michael V. (Tyrone, PA); Kernan, John R. (Loganton, PA)

    2000-02-22

    An automated electrophoretic system is disclosed. The system employs a capillary cartridge having a plurality of capillary tubes. The cartridge has a first array of capillary ends projecting from one side of a plate. The first array of capillary ends are spaced apart in substantially the same manner as the wells of a microtitre tray of standard size. This allows one to simultaneously perform capillary electrophoresis on samples present in each of the wells of the tray. The system includes a stacked, dual carousel arrangement to eliminate cross-contamination resulting from reuse of the same buffer tray on consecutive executions from electrophoresis. The system also has a gel delivery module containing a gel syringe/a stepper motor or a high pressure chamber with a pump to quickly and uniformly deliver gel through the capillary tubes. The system further includes a multi-wavelength beam generator to generate a laser beam which produces a beam with a wide range of wavelengths. An off-line capillary reconditioner thoroughly cleans a capillary cartridge to enable simultaneous execution of electrophoresis with another capillary cartridge. The streamlined nature of the off-line capillary reconditioner offers the advantage of increased system throughput with a minimal increase in system cost.

  3. Theory of Edge Capillary-Gravity Waves

    NASA Astrophysics Data System (ADS)

    Muzylev, S. V.; Bulgakov, S. N.

    2004-12-01

    We consider a body of fluid in equilibrium in a gravitational field and having a free surface and a plane-sloping beach with a straight coastline. If, under the action of some external disturbances, the surface is moved its equilibrium position, motion will occur in the fluid. This motion will be propagated along the coast in the form of waves, which are driven under the action of gravity and surface tension forces. We call these waves edge capillary-gravity waves, if their amplitude decays exponentially with distance from the coast. The fluid is considered inviscid, irrotational and incompressible. Under these conditions the velocity potencial satisfies the Laplace's equation everywhere in the fluid. The boundary conditions are such that the normal velocity at the bottom is zero and on the free surface in the presence of surface tension the linearized kinematic and dynamic boundary conditions are satisfied. The main difficulty for solution of this problem is that the variables are not separated. We present explicit solutions for all modes of the edge capillary-gravity waves and the dispersion equation. Capillary forces affect markedly the edge gravity waves profiles over the high frequency range. The peaks and lows have become larger as compared to pure edge gravity waves, dependence on the radial coordinate becomes more complicated, and a number of zeros of a mode might not coincide with the number of the mode. When ignoring capillary forces, our results are in complete agreement with the classic results of Ursell (1952) for the edge gravity waves on a sloping beach.

  4. Unaffectedness of improved wettability on critical heat flux enhancement with TiO2 sputtered surface

    NASA Astrophysics Data System (ADS)

    Maeng, Yun Hwan; Song, Sub Lee; Lee, Jae Young

    2016-02-01

    The improvement of surface wettability has been considered as a key factor of nanofluid critical heat flux (CHF) enhancement. However, the authors found that improved wettability did not influence on CHF at all. In this paper, the independent effect of surface wettability on CHF was experimentally investigated. The wettability of surface was controlled by DC plasma sputtering of TiO2 without any formation of porous structure. By controlling sputtering time of TiO2 from 12 s to 600 s, various contact angles were obtained from 62° to 11°. Compared to 82° of the bare surface, wettability was improved for all sputtered surface, but CHF was not changed meaningfully. The CHF data had no meaningful relationship at all with the variation of contact angle, so we concluded that wettability cannot be a main parameter of CHF and its enhancement.

  5. CHARACTERIZATION OF MIXED WETTABILITY AT DIFFERENT SCALES AND ITS IMPACT ON OIL RECOVERY EFFICIENCY

    SciTech Connect

    Mukul M. Sharma; George J. Hirasaki

    2003-09-01

    The objectives of the this research project were to: (1) Quantify the pore scale mechanisms that determine the wettability state of a reservoir; (2) Study the effect of crude oil, brine and mineral compositions in the establishment of mixed wet states; (3) Clarify the effect of mixed-wettability on oil displacement efficiency in waterfloods; and (4) Develop a new tracer technique to measure wettability, fluid distributions, residual saturations and relative permeabilities.

  6. Enhanced oil recovery. Reservoir engineer suggests working with capillary forces

    SciTech Connect

    Gill, D.

    1981-04-01

    Enhanced oil recovery (EOR) production results have been disappointing not only because of the low domestic prices that used to prevail, but also because technology has not been good enough. An entirely new EOR technology based on working with rather than against the natural capillary forces within a reservoir must be developed. There is a natural tendency of hydrocarbon fluids to flow under the twin forces of gravity and capillary action back into empty or watered-out sections of reservoirs that have already been produced to their economic limits. Mathematical models of how surfactants or solvents could be used to speed up this normal gravity resegregation of fluids in given types of reservoirs are being developed. The theory is that if solvents or surfactants are pumped into wells and allowed to speed up natural processes, gravity and natural capillary action will draw the oil into already depleted reservoirs so it can be pumped out.

  7. Characterization of Mixed Wettability at Different Scales and its Impact on Oil Recovery Efficiency

    SciTech Connect

    Sharma, Mukul M.; Hirasaki, George J.

    2002-01-28

    The objectives of this project was to: (1) quantify the pore scale mechanisms that determine the wettability state of a reservoir, (2) study the effect of crude oil, brine and mineral compositions in the establishment of mixed wet states, (3) clarify the effect of mixed - wettability on oil displacement efficiency in waterfloods, (4) develop a new tracer technique to measure wettability, fluid distributions, residual saturation's and relative permeabilities, and (5) develop methods for properly incorporating wettability in up-scaling from pore to core to reservoir scales.

  8. Capillary reference half-cell

    DOEpatents

    Hall, S.H.

    1996-02-13

    The present invention is a reference half-cell electrode wherein intermingling of test fluid with reference fluid does not affect the performance of the reference half-cell over a long time. This intermingling reference half-cell may be used as a single or double junction submersible or surface reference electrode. The intermingling reference half-cell relies on a capillary tube having a first end open to reference fluid and a second end open to test fluid wherein the small diameter of the capillary tube limits free motion of fluid within the capillary to diffusion. The electrode is placed near the first end of the capillary in contact with the reference fluid. The method of operation of the present invention begins with filling the capillary tube with a reference solution. After closing the first end of the capillary, the capillary tube may be fully submerged or partially submerged with the second open end inserted into test fluid. Since the electrode is placed near the first end of the capillary, and since the test fluid may intermingle with the reference fluid through the second open end only by diffusion, this intermingling capillary reference half-cell provides a stable voltage potential for long time periods. 11 figs.

  9. Capillary reference half-cell

    DOEpatents

    Hall, Stephen H.

    1996-01-01

    The present invention is a reference half-cell electrode wherein intermingling of test fluid with reference fluid does not affect the performance of the reference half-cell over a long time. This intermingling reference half-cell may be used as a single or double junction submersible or surface reference electrode. The intermingling reference half-cell relies on a capillary tube having a first end open to reference fluid and a second end open to test fluid wherein the small diameter of the capillary tube limits free motion of fluid within the capillary to diffusion. The electrode is placed near the first end of the capillary in contact with the reference fluid. The method of operation of the present invention begins with filling the capillary tube with a reference solution. After closing the first end of the capillary, the capillary tube may be fully submerged or partially submerged with the second open end inserted into test fluid. Since the electrode is placed near the first end of the capillary, and since the test fluid may intermingle with the reference fluid through the second open end only by diffusion, this intermingling capillary reference half-cell provides a stable voltage potential for long time periods.

  10. Enantioseparations by capillary electrochromatography.

    PubMed

    Fanali, S; Catarcini, P; Blaschke, G; Chankvetadze, B

    2001-09-01

    The review summarizes recent developments in enantioseparations by capillary electrochromatography (CEC). Selected fundamental aspects of CEC are discussed in order to stress those features which may allow the success of this technique in the competitive field of enantioseparations. In addition, the comparative characteristics of the different modes of chiral CEC and the stationary phases are presented. The effects of the characteristics of the stationary and liquid phases and operational conditions on the separation results are discussed. Finally, some future trends are briefly addressed. PMID:11589273

  11. Capillary suspensions: Particle networks formed through the capillary force

    PubMed Central

    Koos, Erin

    2014-01-01

    The addition of small amounts of a secondary fluid to a suspension can, through the attractive capillary force, lead to particle bridging and network formation. The capillary bridging phenomenon can be used to stabilize particle suspensions and precisely tune their rheological properties. This effect can even occur when the secondary fluid wets the particles less well than the bulk fluid. These materials, so-called capillary suspensions, have been the subject of recent research studying the mechanism for network formation, the properties of these suspensions, and how the material properties can be modified. Recent work in colloidal clusters is summarized and the relationship to capillary suspensions is discussed. Capillary suspensions can also be used as a pathway for new material design and some of these applications are highlighted. Results obtained to date are summarized and central questions that remain to be answered are proposed in this review. PMID:25729316

  12. Ultrasound assisted cleaning of ceramic capillary filter.

    PubMed

    Pirkonen, P; Grönroos, A; Heikkinen, J; Ekberg, B

    2010-08-01

    Research in the fields of filtration and dewatering connected with the use of ultrasound (US) has been carried out mainly with small laboratory-scale batch or continuously operating devices. So far the only large scale industrial cake filtration applications have been developed and manufactured by Larox Oyj for mining industry. These applications apply ultrasound for cleaning of ceramic capillary action elements having at maximum total filtration area of approximately 150 m(2). Several hundreds of filter units have been delivered worldwide during the past two decades. PMID:19932635

  13. Tapered capillary optics

    DOEpatents

    Hirsch, Gregory

    1998-01-01

    A metal or glass wire is etched with great precision into a very narrowly tapering cone which has the shape of the desired final capillary-optics bore. By controlling the rate of removal of the wire from an etchant bath, a carefully controlled taper is produced. A sensor measures the diameter of the wire as it leaves the surface of the etchant. This signal is used for feedback control of the withdrawal speed. The etched wire undergoes a treatment to produce an extremely low surface-roughness. The etched and smoothed wire is coated with the material of choice for optimizing the reflectivity of the radiation being focused. This could be a vacuum evaporation, sputtering, CVD or aqueous chemical process. The coated wire is either electroplated, built up with electroless plating, or encapsulated in a polymer cylinder such as epoxy to increase the diameter of the wire for easier handling and greater robustness. During this process, the wire is vertically oriented and tensioned to assure that the wire is absolutely straight. The coated and electroformed wire is bonded to a flat, rigid substrate and is then periodically segmented by cutting or etching a series of narrow slits or grooves into the wire. The wire is vertically oriented and tensioned during the bonding process to assure that it is straight. The original wire material is then chemically etched away through the slits or otherwise withdrawn to leave the hollow internal bore of the final tapered-capillary optical element.

  14. Surfactant loss: Effects of temperature, salinity, and wettability

    SciTech Connect

    Noll, L.A.; Gall, B.L.; Crocker, M.E.; Olsen, D.K.

    1989-05-01

    Adsorption of sodium dodecylsulfate, Triton X-100, decyltrimethylammonium bromide surfactants onto silica gel and Berea sandstone mineral surfaces has been studied as a function of temperature, solution salt concentration, and mineral surface wettability. Adsorption studies using a flow calorimeter were conducted using pure surfactants and minerals. The studies were then extended to the adsorption of one type of commercial surfactant onto both consolidated and crushed Berea sandstone using column techniques. This has allowed the comparison of different methods to evaluate surfactant losses from flowing rather than static surfactant solutions. 20 refs., 15 figs., 37 tabs.

  15. Morphology of adsorbed polymers and solid surface wettability.

    PubMed

    Kaggwa, Gillian B; Froebe, Stefanie; Huynh, Le; Ralston, John; Bremmell, Kristen

    2005-05-10

    The adsorption of a polyacrylamide (MW 14600) and two polysaccharides (MW 9260 and 706 x 10(3)) onto model silica surfaces of different hydrophobicities was investigated. In all cases, adsorption adhered to the Freundlich isotherm, reflecting the heterogeneous character of the solid substrates. The latter strongly influenced the character of the adsorbed polymer, with morphologies from chainlike structures to thin films and patches being observed. Surface roughness, polymer type, and molecular weight also play roles in controlling adsorbed polymer morphology. Surface wettability is strongly influenced by the thickness of the adsorbed layer. PMID:16032891

  16. Tailoring the wettability of nanocrystalline TiO 2 films

    NASA Astrophysics Data System (ADS)

    Liang, Qiyu; Chen, Yan; Fan, Yuzun; Hu, Yong; Wu, Yuedong; Zhao, Ziqiang; Meng, Qingbo

    2012-01-01

    The water contact angle (WCA) of nanocrystalline TiO2 films was adjusted by fluoroalkylsilane (FAS) modification and photocatalytic lithography. FAS modification made the surface hydrophobic with the WCA up to ?156, while ultraviolet (UV) irradiation changed surface to hydrophilic with the WCA down to ?0. Both the hydrophobicity and hydrophilicity were enhanced by surface roughness. The wettability can be tailored by varying the concentration of FAS solution and soaking time, as well as the UV light intensity and irradiation time. Additionally, with the help of photomasks, hydrophobic-hydrophilic micropatterns can be fabricated and manifested via area-selective deposition of polystyrene particles.

  17. Mercury ion responsive wettability and oil/water separation.

    PubMed

    Xu, Liangxin; Liu, Na; Cao, Yingze; Lu, Fei; Chen, Yuning; Zhang, Xiaoyong; Feng, Lin; Wei, Yen

    2014-08-27

    A novel Hg(2+) responsive oil/water separation mesh with poly(acrylic acid) hydrogel coating is reported. The mesh can separate oil and water because of the superhydrophilicity of the poly(acrylic acid) hydrogel coating on the mesh, and switch the wettability based on the chelation between Hg(2+) and poly(acrylic acid) . The reversible change in oil contact angle of as-prepared mesh is about 149 after immersion in Hg(2+) solution. This mesh is an ideal candidate for oil-polluted water purification, especially for water that contains Hg(2+) contaminant. PMID:25110804

  18. On Capillary Rise and Nucleation

    ERIC Educational Resources Information Center

    Prasad, R.

    2008-01-01

    A comparison of capillary rise and nucleation is presented. It is shown that both phenomena result from a balance between two competing energy factors: a volume energy and a surface energy. Such a comparison may help to introduce nucleation with a topic familiar to the students, capillary rise. (Contains 1 table and 3 figures.)

  19. Biomedical applications of capillary electrophoresis

    NASA Astrophysics Data System (ADS)

    Kartsova, L. A.; Bessonova, E. A.

    2015-08-01

    The review deals with modern analytical approaches used in capillary electrophoresis for solving medical and biological problems: search for biomarkers of various diseases and rapid diagnosis based on characteristic profiles of biologically active compounds by capillary electrophoresis with mass spectrometric detection; monitoring of the residual drugs in biological fluids for evaluating the efficiency of drug therapy; testing of the enantiomeric purity of pharmaceutical products; the use of novel materials as components of stationary and pseudo-stationary phases in capillary electrophoresis and capillary electrochromatography to increase the selectivity of separation of components of complex matrices; and identification of various on-line preconcentration techniques to reduce the detection limits of biologically active analytes. A topical trend in capillary electrophoresis required in clinical practice, viz., the design of microfluidic systems, is discussed. The bibliography includes 173 references.

  20. Noise suppressing capillary separation system

    DOEpatents

    Yeung, E.S.; Xue, Y.

    1996-07-30

    A noise-suppressing capillary separation system for detecting the real-time presence or concentration of an analyte in a sample is provided. The system contains a capillary separation means through which the analyte is moved, a coherent light source that generates a beam which is split into a reference beam and a sample beam that irradiate the capillary, and a detector for detecting the reference beam and the sample beam light that transmits through the capillary. The laser beam is of a wavelength effective to be absorbed by a chromophore in the capillary. The system includes a noise suppressing system to improve performance and accuracy without signal averaging or multiple scans. 13 figs.

  1. Capillary optics for radiation focusing

    SciTech Connect

    Peurrung, A.J.; Reeder, P.L.; Bliss, M.; Craig, R.A.; Lepel, E.A.; Stromswold, D.C.; Stoffels, J.; Sunberg, D.S.; Tenny, H.

    1996-11-01

    Capillary lens technology may ultimately bring benefits to neutron and x-ray-based science like conventional lenses with visible light. Although the technology is not yet 10 years old, these lenses have already had a significant impact in engineering, science, and medicine. Capillary lenses are advantageous when it is desirable to increase the radiation flux at a location without regard to its angular divergence. PNNL has worked to improve the technology in several ways. A single, optimally tapered capillary was manufactured, which allows intensity gains of a factor of 270 for an initially parallel, incident x-ray beam. Feasibility of constructing neutron lenses using {sup 58}Ni (particularly effective at reflecting neutrons) has been explored. Three applications for capillary optics have been identified and studied: neutron telescope, Gandolphi x-ray diffractometry, and neutron radiotherapy. A brief guide is given for determining which potential applications are likely to be helped by capillary optics.

  2. Pore-lining composition and capillary breakthrough pressure of mudstone caprocks : sealing efficiency at geologic CO2 storage sites.

    SciTech Connect

    Heath, Jason E.; Nemer, Martin B.; McPherson, Brian J. O. L.; Dewers, Thomas A.; Kotula, Paul Gabriel

    2010-12-01

    Subsurface containment of CO2 is predicated on effective caprock sealing. Many previous studies have relied on macroscopic measurements of capillary breakthrough pressure and other petrophysical properties without direct examination of solid phases that line pore networks and directly contact fluids. However, pore-lining phases strongly contribute to sealing behavior through interfacial interactions among CO2, brine, and the mineral or non-mineral phases. Our high resolution (i.e., sub-micron) examination of the composition of pore-lining phases of several continental and marine mudstones indicates that sealing efficiency (i.e., breakthrough pressure) is governed by pore shapes and pore-lining phases that are not identifiable except through direct characterization of pores. Bulk X-ray diffraction data does not indicate which phases line the pores and may be especially lacking for mudstones with organic material. Organics can line pores and may represent once-mobile phases that modify the wettability of an originally clay-lined pore network. For shallow formations (i.e., < {approx}800 m depth), interfacial tension and contact angles result in breakthrough pressures that may be as high as those needed to fracture the rock - thus, in the absence of fractures, capillary sealing efficiency is indicated. Deeper seals have poorer capillary sealing if mica-like wetting dominates the wettability. We thank the U.S. Department of Energy's National Energy Technology Laboratory and the Office of Basic Energy Sciences, and the Southeast and Southwest Carbon Sequestration Partnerships for supporting this work.

  3. Pore-lining composition and capillary breakthrough pressure of mudstone caprocks : sealing efficiency of geologic CO2 storage sites.

    SciTech Connect

    Petrusak, Robin; Heath, Jason E.; McPherson, Brian J. O. L.; Dewers, Thomas A.; Kotula, Paul Gabriel

    2010-08-01

    Subsurface containment of CO2 is predicated on effective caprock sealing. Many previous studies have relied on macroscopic measurements of capillary breakthrough pressure and other petrophysical properties without direct examination of solid phases that line pore networks and directly contact fluids. However, pore-lining phases strongly contribute to sealing behavior through interfacial interactions among CO2, brine, and the mineral or non-mineral phases. Our high resolution (i.e., sub-micron) examination of the composition of pore-lining phases of several continental and marine mudstones indicates that sealing efficiency (i.e., breakthrough pressure) is governed by pore shapes and pore-lining phases that are not identifiable except through direct characterization of pores. Bulk X-ray diffraction data does not indicate which phases line the pores and may be especially lacking for mudstones with organic material. Organics can line pores and may represent once-mobile phases that modify the wettability of an originally clay-lined pore network. For shallow formations (i.e., < {approx}800 m depth), interfacial tension and contact angles result in breakthrough pressures that may be as high as those needed to fracture the rock - thus, in the absence of fractures, capillary sealing efficiency is indicated. Deeper seals have poorer capillary sealing if mica-like wetting dominates the wettability.

  4. Capillary interconnect device

    DOEpatents

    Renzi, Ronald F. (Tracy, CA)

    2007-12-25

    A manifold for connecting external capillaries to the inlet and/or outlet ports of a microfluidic device for high pressure applications is provided. The fluid connector for coupling at least one fluid conduit to a corresponding port of a substrate that includes: (i) a manifold comprising one or more channels extending therethrough wherein each channel is at least partially threaded, (ii) one or more threaded ferrules each defining a bore extending therethrough with each ferrule supporting a fluid conduit wherein each ferrule is threaded into a channel of the manifold, (iii) a substrate having one or more ports on its upper surface wherein the substrate is positioned below the manifold so that the one or more ports is aligned with the one or more channels of the manifold, and (iv) means for applying an axial compressive force to the substrate to couple the one or more ports of the substrate to a corresponding proximal end of a fluid conduit.

  5. Designer-Wet Micromodels for Studying Potential Changes in Wettability during Microbial Enhanced Oil Recovery

    NASA Astrophysics Data System (ADS)

    Armstrong, R. T.; Wildenschild, D.

    2010-12-01

    Microbial Enhanced Oil Recovery (MEOR) is a process where microorganisms are used for tertiary recovery of oil. Some bacteria can facilitate the mobilization of oil through the production of amphiphilic compounds called biosurfactants that reduce the interfacial tension (IFT) between immiscible phases. Additionally, most bacteria have an inclination to colonize surfaces and form biofilm, which can change a reservoir's wetting properties or clog preferential flow paths. Herein, we aim to understand changes in wettability during MEOR under mixed wettability conditions within silicon etched micromodels and to identify the type of oil field (i.e. based on wettability) in which MEOR is likely to be most profitable. To quantify porous media wettability, macro-scale indexes (obtained with techniques such as the Carter or Amott methods) are used regularly. However, these measurements lack the capability for characterization of changes in wettability during MEOR treatment, and only provide macro-scale information. In an effort to understand micro-scale temporal and spatial changes in wettability we measure interfacial curvature from stereo microscope images using level set methods. Curvature, from the perspective of the oil phase, is positive for a concave interface (i.e. water-wet surface) and negative for a convex interface (i.e. oil-wet surface). Thus, shifts in the radius of curvature distribution (i.e. from positive to negative or conversely) are indicative of wettability changes. Both curvature distributions using level-set methods and the Carter method are used to characterize wettability before and after microbial treatment. In preliminary studies aimed at understanding wettability changes due to microbial surface interactions by Bacillus mojavensis JF-2, oil droplets were placed on glass slides suspended in growth media and the resulting contact angle was measured over time. Results showed that a water-wet surface will become more water wet as JF-2 accumulated in the growth media and/or at the oil/water/solid interfaces. Conversely, an oil-wet surface would not become water-wet. These experiments demonstrated that a microbes ability to change wettability, as measured by contact angle, is dependent upon the initial wettability state. To study the dependence of wettability changes on initial wettability designer-wet micromodels were prepared by freezing a liquid within a fraction of a micromodel pore space followed by treatment with octodecylthrichlorosilane (OTS). Locations within the micromodel where the liquid was frozen remained water-wet and water-wet to oil-wet surface ratios were produced in ratios: 1:5, 5:5, and 5:1. The method for creating designer-wet micromodels and preliminary results on wettability change using JF-2 within the micromodel system will be presented.

  6. Capillaries for use in a multiplexed capillary electrophoresis system

    DOEpatents

    Yeung, E.S.; Chang, H.T.; Fung, E.N.

    1997-12-09

    The invention provides a side-entry optical excitation geometry for use in a multiplexed capillary electrophoresis system. A charge-injection device is optically coupled to capillaries in the array such that the interior of a capillary is imaged onto only one pixel. In Sanger-type 4-label DNA sequencing reactions, nucleotide identification (``base calling``) is improved by using two long-pass filters to split fluorescence emission into two emission channels. A binary poly(ethyleneoxide) matrix is used in the electrophoretic separations. 19 figs.

  7. Capillary ratchet: Hydrodynamics of capillary feeding in shorebirds

    NASA Astrophysics Data System (ADS)

    Prakash, Manu; Quere, David; Bush, John

    2008-03-01

    Bill morphologies are highly specialized to particular foraging strategies in birds, as is apparent from the large diversity of beak shapes observed in nature. Here we present an experimental and analytical study of capillary feeding in shorebirds. We highlight the critical role of contact angle hysteresis in capillary feeding. Our study provides a simple physical rationalization for the observation of multiple mandibular spreading cycles in feeding, necessary to overcome contact line resistance. We also find a unique geometrical optima in beak opening and closing angles for the most efficient drop transport. This capillary ratchet mechanism may also find applications in micro scale fluid transport, such as valveless pumping of fluid drops.

  8. Capillaries for use in a multiplexed capillary electrophoresis system

    DOEpatents

    Yeung, Edward S. (Ames, IA); Chang, Huan-Tsang (Silver Spring, MD); Fung, Eliza N. (Ames, IA)

    1997-12-09

    The invention provides a side-entry optical excitation geometry for use in a multiplexed capillary electrophoresis system. A charge-injection device is optically coupled to capillaries in the array such that the interior of a capillary is imaged onto only one pixel. In Sanger-type 4-label DNA sequencing reactions, nucleotide identification ("base calling") is improved by using two long-pass filters to split fluorescence emission into two emission channels. A binary poly(ethyleneoxide) matrix is used in the electrophoretic separations.

  9. Controllable wettability and morphology of electrodeposited surfaces on zinc substrates

    NASA Astrophysics Data System (ADS)

    Zhang, Binyan; Lu, Shixiang; Xu, Wenguo; Cheng, Yuanyuan

    2016-01-01

    Superhydrophobic surfaces combining hierarchical micro/nanostructures were fabricated on zinc substrates by etching in hydrochloric acid solution, electrodeposition of ZnO coatings and subsequent thermal annealing. The optimal coatings were electrodeposited at -1.25 V for 900 s on the etched zinc substrates and then annealed at 200 °C for 60 min, which could achieve a maximum water contact angle of 170 ± 2° and an ultra-low sliding angle of approximately 0°. By conducting SEM and water CA analysis, we found that the morphology and wettability of prepared samples were controllable by the fabrication process. Interestingly, even without any additional modification, the samples prepared under different electrodeposition conditions (including Zn(CH3COO)2 concentration from 5 mM to 40 mM and deposition time from 300 s to 1500 s) exhibited superhydrophobic character. The influences of the Zn(CH3COO)2 concentration, deposition time, annealing temperature and annealing time on the wetting behaviors were also discussed in detail. Such superhydrophobic surfaces possess long-term stability, and good corrosion resistance as well as self-cleaning ability. In addition, the anti-icing properties of the ZnO films were investigated. These surfaces could be rapidly and reversibly switched between superhydrophobicity and superhydrophilicity by alternating UV illumination and dark storage or thermal annealing. The intelligent switchable surfaces with controllable wettability and morphology offer possibilities for chemical, biological, electronic and microfluidic applications.

  10. Effects of surface wettability on fast liquid transfer

    NASA Astrophysics Data System (ADS)

    Chen, H.; Tang, T.; Amirfazli, A.

    2015-11-01

    A systematic experimental study was performed to understand the role of surface contact angles in affecting the process of fast liquid transfer. Surfaces with different wettabilities were used, and the transfer ratio (α, the amount of liquid transferred to the acceptor surface over the total amount of liquid) was measured for each pair of surfaces. A numerical model based on the volume of fluid method was developed to help understand the experimental results. The surface wettability was shown to significantly affect the boundaries between three regimes based on stretching speeds: quasi-static (surface force dominated), transition (surface/viscous/inertia forces all important) and dynamic (viscous/inertia forces dominated). Specifically, the values of the boundary speeds were found to increase with |α0 - 0.5|, where α0 is the transfer ratio in the quasi-static regime, and α0 is governed by the surface receding contact angles. Based on our results, an empirical equation to describe the transfer ratio as function of stretching speed was proposed. This equation can also be used as a prediction tool for the value of α for a fast transfer system.

  11. Wettability of low temperature solder alloys for step-soldering

    SciTech Connect

    Hosking, F.M.; Vianco, P.T.; Frear, D.R.

    1991-01-01

    The electronics industry relies on step-soldering during device attachment or subsequent reworking of heavily populated hybrid microcircuits and multilevel networks. Although there are many low to intermediate melting solder alloys that are commercially available, their wettability on typical base metals, such as Cu, Ni, Au, and Sn, are not well characterized. This investigation examines the wetting behavior of several In, Sn, Pb, Bi, and Ag containing solder alloys on Ni-Sn plated aluminum alloy substrates with soldering temperatures ranging from 145 to 200{degrees}C. Two rosin mildly activated (RMA) fluxes were included in the study. The wettability experiments were conducted with a Sandia designed wetting balance system. Wetting differences were observed between the two fluxes. The more active flux gave better wetting results and less variability in the meniscus terminations at the lower soldering temperatures. Wetting generally varied from adequate to very good. The Bi-bearing alloys generally gave the lowest wetting values. Work is in progress to determine the effects of aging on intermetallic growth and subsequent mechanical strength. 12 refs., 12 figs., 2 tabs.

  12. Initial biocompatibility of plasma polymerized hexamethyldisiloxane films with different wettability

    NASA Astrophysics Data System (ADS)

    Krasteva, N. A.; Toromanov, G.; Hristova, K. T.; Radeva, E. I.; Pecheva, E. V.; Dimitrova, R. P.; Altankov, G. P.; Pramatarova, L. D.

    2010-11-01

    Understanding the relationships between material surface properties, behaviour of adsorbed proteins and cellular responses is essential to design optimal material surfaces for tissue engineering. In this study we modify thin layers of plasma polymerized hexamethyldisiloxane (PPHMDS) by ammonia treatment in order to increase surface wettability and the corresponding biological response. The physico-chemical properties of the polymer films were characterized by contact angle (CA) measurements and Fourier Transform Infrared Spectroscopy (FTIR) analysis.Human umbilical vein endothelial cells (HUVEC) were used as model system for the initial biocompatibility studies following their behavior upon preadsorption of polymer films with three adhesive proteins: fibronectin (FN), fibrinogen (FG) and vitronectin (VN). Adhesive interaction of HUVEC was evaluated after 2 hours by analyzing the overall cell morphology, and the organization of focal adhesion contacts and actin cytoskeleton. We have found similar good cellular response on FN and FG coated polymer films, with better pronounced vinculin expression on FN samples while. Conversely, on VN coated surfaces the wettability influenced significantly initial celular interaction spreading. The results obtained suggested that ammonia plasma treatment can modulate the biological activity of the adsorbed protein s on PPHMDS surfaces and thus to influence the interaction with endothelial cells.

  13. Fog collecting biomimetic surfaces: Influence of microstructure and wettability.

    PubMed

    Azad, M A K; Ellerbrok, D; Barthlott, W; Koch, K

    2015-01-01

    We analyzed the fog collection efficiency of three different sets of samples: replica (with and without microstructures), copper wire (smooth and microgrooved) and polyolefin mesh (hydrophilic, superhydrophilic and hydrophobic). The collection efficiency of the samples was compared in each set separately to investigate the influence of microstructures and/or the wettability of the surfaces on fog collection. Based on the controlled experimental conditions chosen here large differences in the efficiency were found. We found that microstructured plant replica samples collected 2-3 times higher amounts of water than that of unstructured (smooth) samples. Copper wire samples showed similar results. Moreover, microgrooved wires had a faster dripping of water droplets than that of smooth wires. The superhydrophilic mesh tested here was proved more efficient than any other mesh samples with different wettability. The amount of collected fog by superhydrophilic mesh was about 5 times higher than that of hydrophilic (untreated) mesh and was about 2 times higher than that of hydrophobic mesh. PMID:25599517

  14. Improved Surface wettability of polyurethane films by Ultraviolet Ozone treatment

    SciTech Connect

    Kuang, Ping; Lee, Jae-Hwang; Kim, Chang-Hwang; Ho, Kai-Ming; Constant, Kristen

    2010-07-01

    The wettability of polyurethane (PU) was altered using ultraviolet ozone (UVO) treatment. The effect of UVO treatment on PU surface chemistry was investigated with various experiments. The direct measurement of sessile drops was employed to quantify the static contact angle of different wetting liquids on homogeneous PU films with various UVO treatment times. The contact angle of DI water droplets was decreased to 17.2{sup o} from 70.04{sup o} after 5 min UVO treatment. The surface free energy of PU films was 51.46 mN m{sup -1} before treatment and was increased to 71.5 mN m{sup -1} after being fully treated. X-ray photoelectron spectroscopy (XPS) analysis shows a significant amount of polar functional species (C-O and C-O bonding) were formed on the PU surface by UVO treatment. atomic force microscopy (AFM) characterization shows the PU surface morphology was different before and after UVO treatment. The effect of water washing on UVO treated surface was also investigated. An aging effect study indicates the UVO modification can sustain the improved wettability with limited hydrophobic recovery, where the DI water contact angle remains constant at around 22{sup o} after the UVO treatment.

  15. Wettability of AlSi5Mg on Spodumene

    NASA Astrophysics Data System (ADS)

    Fankhnel, Beate; Stelter, Michael; Voigt, Claudia; Aneziris, Christos G.

    2015-02-01

    The development of new filters for the aluminum industry requires investigations on the wettability of aluminum and its alloys on novel filter materials. The requested filter effects require not only an adequate wetting but also information about the interaction between the filter material and the metal. In the present work the wettability of an AlSi5Mg alloy on spodumene (LiAl[Si2O6]) containing substrates is investigated using the sessile drop technique. These measurements were carried out at 1223 K (950 C) under vacuum. The spodumene-based substrates showed a completely different wetting behavior compared with an alumina substrate. The contact angel reduced more quickly and leveled out at a lower value (75 2 deg) than in case of a pure alumina substrate (90 1 deg). The reason for this behavior is a reaction between the LiAl(Si2O6) and the alloy droplet which supported deoxidation and formed a silica-rich reaction layer at the droplet/substrate interface.

  16. Effects of aluminium surface morphology and chemical modification on wettability

    NASA Astrophysics Data System (ADS)

    Rahimi, M.; Fojan, P.; Gurevich, L.; Afshari, A.

    2014-03-01

    Aluminium alloys are some of the predominant metals in industrial applications such as production of heat exchangers, heat pumps. They have high heat conductivity coupled with a low specific weight. In cold working conditions, there is a risk of frost formation on the surface of aluminium in the presence of water vapour, which can lead to the deterioration of equipment performance. This work addresses the methods of surface modification of aluminium and their effect of the underlying surface morphology and wettability, which are the important parameters for frost formation. Three groups of real-life aluminium surfaces of different morphology: unpolished aluminium, polished aluminium, and aluminium foil, were subjected to surface modification procedures which involved the formation of a layer of hydrophilic hyperbranched polyethyleneglycol via in situ polymerization, molecular vapour deposition of a monolayer of fluorinated silane, and a combination of those. The effect of these surface modification techniques on roughness and wettability of the aluminium surfaces was elucidated by ellipsometry, contact angle measurements and atomic force microscopy. We demonstrated that by employing different types of surface modifications the contact angle of water droplets on aluminium samples can be varied from 12° to more than 120°. A crossover from Cassie-Baxter to Wenzel regime upon changing the surface roughness was also observed.

  17. Impact of Wettability on Fracturing of Nano-Granular Materials

    NASA Astrophysics Data System (ADS)

    Trojer, M.; Juanes, R.

    2014-12-01

    Hydraulic fracturing, or fracking, is a well-known reservoir stimulation technique, by which the permeability of the near-wellbore region is enhanced through the creation of tensile fractures within the rock, formed in the direction perpendicular to the least principal stress. While it is well known that fracturing of granular media strongly depends on the type of media, the pore fluids, and the fracking fluids, the interplay between multiphase flow, wettability and fracture mechanics of shale-like (nano-granular) materials remains poorly understood. Here, we study experimentally the dynamics of multiphase-flow fracking in nano-porous media and its dependence on the wetting properties of the system. The experiments consist in saturating a thin bed of glass beads with a viscous fluid, injecting a less viscous fluid, and imaging the invasion morphology. We investigate three control parameters: the injection rate of the less-viscous invading phase, the confining stress, and the contact angle, which we control by altering the surface chemistry of the beads and the Hele-Shaw cell. We quantify the dynamic fracture pattern by means of particle image velocimetry (PIV), and elucidate the role of wettability on the emerging flow physics at the length scale of the viscous-frictional instability.

  18. Salinity Influence on Interfacial Area, Wettability, and NAPL Recovery

    NASA Astrophysics Data System (ADS)

    Zhong, L.; Valenta, M. M.

    2007-12-01

    Wettability, the tendency of rock or sediment particle surfaces to be preferentially wet by one fluid phase, has a strong influence on the distribution and flow of immiscible fluids in oil reservoirs or aquifers. The efficiency of oil and non-aqueous phase liquid (NAPL) recovery processes and the displacement and production of oil/NAPL by fluids injected into the reservoir or aquifer depend on the wetting properties of the rock/sediment particle surfaces. Effects of salinity on wettability and residual oil saturation during water flooding are of particular interest in the petroleum industry with some reservoirs. It was indicated that the residual oil saturation may be reduced significantly by flooding with low salinity water instead of seawater or brine. This observation may be also true in NAPL recovery from contaminated aquifers. NAPL recovery enhancement may be achieved by manipulating the salinity of the remedial fluid. Two sets of 8 core-flooding column experiments have been completed, using decane and Alaska North Slope (ANS) crude oil as surrogate NAPLs. Unconsolidated sand packs were used as representative porous media. NAPL removal was conducted by flushing column at residual NAPL saturation using water with salinity ranging from 0% to 8% wt of NaCl. The NAPL-water interfacial area (anw, cm-1) was measured and used as an indicator for the wettability characteristics of the packed sand. Sodium Dodecyl Benzene Sulfonate (SDBS) was used as an interfacial partitioning tracer and Pentafluoro Benzoic acid (PFBA) was used as a non-reactive and non-partitioning tracer. NAPL was imbibed into an initially water saturated column, using positive displacement methods. NAPL was then flushed out using water at certain salinity. When the column attained a residual NAPL saturation after each water flushing displacement, the partitioning and conservative tracer experiments were conducted separately, to characterize the specific NAPL-water interfacial areas, and the wettability status. Water with 8%, 4%, 2%, 0% wt NaCl salinity was used to displace NAPL from the sand column sequentially. The interfacial tension (IFT) between the salinity water and the ANS oil was monitored. The residual oil saturations indicated that the fraction of NAPL retained in the column increased after water flushing as the salinity in the displacing water increased from 0 to 8%, clearly confirming the earlier findings that lower salinity may cause additional oil to be released. The NAPL-water interfacial area, anw, does not show a monotonic dependence on salinity; instead, anw shows an increasing trend with increasing salinity in the lower salinity range, and the opposite trend at high salinity values. The maximum anw was obtained in systems flushed with 2% salinity water. This trend appears to be consistent with a similar nonlinear dependence of interfacial tension on salinity, and might be an indication of wettability alternation. The observation of this research shread lights on the optimum operation in NAPL removal. The IFT change between NAPL and the salinity water might be attributed to the enhanced NAPL recovery.

  19. Integrated multiplexed capillary electrophoresis system

    DOEpatents

    Yeung, Edward S. (Ames, IA); Tan, Hongdong (Ames, IA)

    2002-05-14

    The present invention provides an integrated multiplexed capillary electrophoresis system for the analysis of sample analytes. The system integrates and automates multiple components, such as chromatographic columns and separation capillaries, and further provides a detector for the detection of analytes eluting from the separation capillaries. The system employs multiplexed freeze/thaw valves to manage fluid flow and sample movement. The system is computer controlled and is capable of processing samples through reaction, purification, denaturation, pre-concentration, injection, separation and detection in parallel fashion. Methods employing the system of the invention are also provided.

  20. Crystal growth from the melt by capillary shaping techniques

    NASA Astrophysics Data System (ADS)

    Ossipyan, Y. A.; Tatarchenko, V. A.

    A method based on the Lyapunov stability theory has been developed for studying the stability of crystallization by capillary shaping techniques (including Czochralski, Stepanov, EFG, Verneuil and floating zone methods). The preliminary results of the analysis of stability shows that the crystallization by capillary shaping technique under microgravitation conditions is more stable in some cases than under the action of gravitation. To get deeper into details of the capillary shaping technique under microgravitation conditions, we have carried out model experiments using two immiscible liquids of equal density and crystallization of sapphire in terrestrial conditions with small Bond number. The experiments on the copper crystallization were realized in the high-altitude rockets. Our experiments on indium crystallization carried out in the orbital space probe Salyut yielded cylindrical specimens.

  1. Capillary-driven self-assembly of microchips on oleophilic/oleophobic patterned surface using adhesive droplet in ambient air

    NASA Astrophysics Data System (ADS)

    Chang, Bo; Sariola, Veikko; Aura, Susanna; Ras, Robin H. A.; Klonner, Maria; Lipsanen, Harri; Zhou, Quan

    2011-07-01

    This letter describes a capillary-driven self-assembly technique using oleophilic/oleophobic patterned surface and adhesive in ambient air environment. We use a topographical microstructure of porous ormocer functionalized with a fluorinated trichlorosilane for the oleophobic area and gold patterns for the oleophilic area. The resulted oleophilic/oleophobic patterns show significant wettability contrast for adhesive (Delo 18507), with a contact angle of 119 on oleophobic part and 53 on the oleophilic part. Self-alignment of SU-8 microchips on the oleophilic/oleophobic patterns has been demonstrated. The results provide a promising solution for self-alignment of microparts using commercial adhesives in ambient air environment.

  2. Evaluation of Reservoir Wettability and its Effect on Oil Recovery.

    SciTech Connect

    Buckley, J.S.

    1998-01-15

    We report on the first year of the project, `Evaluation of Reservoir Wettability and its Effect on Oil Recovery.` The objectives of this five-year project are (1) to achieve improved understanding of the surface and interfacial properties of crude oils and their interactions with mineral surfaces, (2) to apply the results of surface studies to improve predictions of oil production from laboratory measurements, and (3) to use the results of this research to recommend ways to improve oil recovery by waterflooding. During the first year of this project we have focused on understanding the interactions between crude oils and mineral surfaces that establish wetting in porous media. As background, mixed-wetting and our current understanding of the influence of stable and unstable brine films are reviewed. The components that are likely to adsorb and alter wetting are divided into two groups: those containing polar heteroatoms, especially organic acids and bases; and the asphaltenes, large molecules that aggregate in solution and precipitate upon addition of n-pentane and similar agents. Finally, the test procedures used to assess the extent of wetting alteration-tests of adhesion and adsorption on smooth surfaces and spontaneous imbibition into porous media are introduced. In Part 1, we report on studies aimed at characterizing both the acid/base and asphaltene components. Standard acid and base number procedures were modified and 22 crude oil samples were tested. Our approach to characterizing the asphaltenes is to focus on their solvent environment. We quantify solvent properties by refractive index measurements and report the onset of asphaltene precipitation at ambient conditions for nine oil samples. Four distinct categories of interaction mechanisms have been identified that can be demonstrated to occur when crude oils contact solid surfaces: polar interactions can occur on dry surfaces, surface precipitation is important if the oil is a poor solvent for its asphaltenes, and acid/base and ion-binding interactions occur in the presence of water. Specific instances when each of these mechanisms is dominant can be identified using crude oils of different acid number, base number, and solvent quality. Part 2 of this project is devoted to improved assessment of wetting. We report on a baseline study of crude oil interactions with mica surfaces that shows wettability alteration characteristics that are comparable to those reported previously for glass surfaces. Mica has advantages over amorphous glass that make it a better choice as a standard surface for wettability testing, especially for tests at high temperatures.

  3. Surface Tension and Capillary Rise

    ERIC Educational Resources Information Center

    Walton, Alan J.

    1972-01-01

    Discussion of the shortcomings of textbook explanations of surface tension, distinguishing between concepts of tension and capillary rise. The arguments require only a clear understanding of Newtonian mechanics, notably potential energy. (DF)

  4. Capillary-gravity wave drag

    NASA Astrophysics Data System (ADS)

    Sun, Shu-Ming; Keller, Joseph B.

    2001-08-01

    Drag due to the production of capillary-gravity waves is calculated for an object moving along the surface of a liquid. Both two and three dimensional objects, moving at large Froude and Weber numbers, are treated.

  5. DNA typing by capillary electrophoresis

    SciTech Connect

    Zhang, N.

    1997-10-08

    Capillary electrophoresis is becoming more and more important in nucleic acid analysis including DNA sequencing, typing and disease gene measurements. This work summarized the background of DNA typing. The recent development of capillary electrophoresis was also discussed. The second part of the thesis showed the principle of DNA typing based on using the allelic ladder as the absolute standard ladder in capillary electrophoresis system. Future work will be focused on demonstrating DNA typing on multiplex loci and examples of disease diagnosis in the on-line format of PCR-CE. Also capillary array electrophoresis system should allow high throughput, fast speed DNA typing. Only the introduction and conclusions for this report are available here. A reprint was removed for separate processing.

  6. Capillary electrophoresis electrospray ionization mass spectrometry interface

    DOEpatents

    Smith, Richard D. (Richland, WA); Severs, Joanne C. (Hayward, CA)

    1999-01-01

    The present invention is an interface between a capillary electrophoresis separation capillary end and an electrospray ionization mass spectrometry emitter capillary end, for transporting an anolyte sample from a capillary electrophoresis separation capillary to a electrospray ionization mass spectrometry emitter capillary. The interface of the present invention has: (a) a charge transfer fitting enclosing both of the capillary electrophoresis capillary end and the electrospray ionization mass spectrometry emitter capillary end; (b) a reservoir containing an electrolyte surrounding the charge transfer fitting; and (c) an electrode immersed into the electrolyte, the electrode closing a capillary electrophoresis circuit and providing charge transfer across the charge transfer fitting while avoiding substantial bulk fluid transfer across the charge transfer fitting. Advantages of the present invention have been demonstrated as effective in providing high sensitivity and efficient analyses.

  7. Effect of wettability alteration on long-term behavior of fluids in subsurface

    NASA Astrophysics Data System (ADS)

    Bandara, Uditha C.; Palmer, Bruce J.; Tartakovsky, Alexandre M.

    2016-01-01

    Wettability is an important factor affecting fluid behavior in the subsurface, including oil, gas, and supercritical {CO}_2 in deep geological reservoirs. For example, {CO}_2 is generally assumed to behave as a non-wetting fluid, which favors safe storage. However, because of chemical heterogeneity of the reservoirs, mixed wettability conditions can exist. Furthermore, recent experiments suggest that with time, the wettability of super-critical {CO}_2 may change from non-wetting to partially wetting due to changes in electrostatic interactions. These changes are caused by chemical reactions between dissolved {CO}_2 and its environment. To date, the effect of wettability alteration and mixed wettability on the long-term fate of injected {CO}_2 has not well been studied. Here, we use the multiphase pairwise force smoothed particle hydrodynamics model to study complex pore-scale processes involved in geological {CO}_2 sequestration, including the effect of spatial and temporal wettability variations on long-term distribution of {CO}_2 in porous media. Results reveal that in the absence of dissolution of supercritical {CO}_2 and precipitation of carbonate minerals (mineral trapping), the amount of trapped supercritical {CO}_2 significantly decreases as the wettability of the porous media changes from brine-wet to partial-wet or {CO}_2 -wet.

  8. Wettability of Oil-Producing Reservoir Rocks as Determined from X-ray Photoelectron Spectroscopy

    PubMed

    Toledo; Araujo; Leon

    1996-11-10

    Wettability has a dominant effect in oil recovery by waterflooding and in many other processes of industrial and environmental interest. Recently, the suggestion has been made that surface science analytical techniques (SSAT) could be used to rapidly determine the wettability of reservoir materials. Here, we bring the capability of X-ray photoelectron spectroscopy (XPS) to bear on the wettability evaluation of producing reservoir rocks. For a suite of freshly exposed fracture surfaces of rocks we investigate the relationship between wettability and surface composition as determined from XPS. The classical wettability index as measured with the Amott-Harvey test is used here as an indicator of the wettability of natural sandstones. The XPS spectra of oil-wet surfaces of rocks reveal the existence of organic carbon and also of an "organic" silicon species, of the kind Si-CH relevant to silanes, having a well-defined binding energy which differs from that of the Si-O species of mineral grains. We provide quantifiable evidence that chemisorbed organic material on the pore surfaces defines the oil-wetting character of various reservoir sandstones studied here which on a mineralogic basis are expected to be water-wet. This view is supported by a strong correlation between C content of pore surfaces and rock wettability. The results also suggest a correlation between organic silicon content on the pore surfaces and rock hydrophobicity. PMID:8954667

  9. An Alternative Approach to Evaluate the Wettability of Carbon Fiber Substrates.

    PubMed

    Sow, Pradeep Kumar; Prass, Sebastian; Mrida, Walter

    2015-10-01

    The wettability of carbon fiber substrate plays an important role in a vast number of electrochemical energy production and storage technologies. Here, we report an alternative approach to evaluate the relative wettability for three substrates with the solid-liquid (S-L) interfacial area as the wettability parameter. We applied electrochemical techniques to quantify the S-L interfacial area and obtained the relative wettability on for three substrates with varying fiber morphology. This work proposes and validates a methodology to experimentally measure the substrate wettability and elucidates important aspects of the relevant wetting phenomena. Our results indicate that the wettability of carbon fiber substrate is affected by the liquid intrusion resulting from the instability of the Cassie-Baxter wetting state and that the contact angle is not dependent on the S-L interfacial area under the droplet. The present technique can be used to characterize the surface wettability of a wide range of conductive surfaces with irregular and multiscale surface roughness features. PMID:26375575

  10. Automatic droplet transportation on a plastic microfluidic device having wettability gradient surface

    NASA Astrophysics Data System (ADS)

    Nakashima, Y.; Nakanishi, Y.; Yasuda, T.

    2015-01-01

    This paper presents a microfluidic device that can automatically transport a droplet on a plastic plate. This device consists of a Cyclo Olefin Polymer (COP) plate and a SiO2 membrane and has wettability gradient surface. Lithographic patterns of hydrophilic SiO2 permitted wettability modification of a hydrophobic COP surface. A series of alternate hydrophobic and hydrophilic wedge-shaped patterns generated a required gradient in wettability. When we dropped a droplet on the wettability gradient surface, it moved along the wettability gradient due to an imbalance between surface tension forces acting on the opposite sides of the droplet edge. The droplet transportation test was carried out using water of 5 ?l. As a result, we succeeded in automatically transporting the droplet on the SiO2/COP wettability gradient pattern. We also carried out droplet transportation in an enclosed microchannel for preventing droplet evaporation using DI (Deionized) water of 5 ?l. In this case, the droplet was automatically transported by forming the wettability gradient pattern at the top and bottom in an enclosed microchannel without evaporation.

  11. Inverse Problem of Capillary Filling

    NASA Astrophysics Data System (ADS)

    Elizalde, Emanuel; Urteaga, Raúl; Koropecki, Roberto R.; Berli, Claudio L. A.

    2014-04-01

    The inverse problem of capillary filling, as defined in this work, consists in determining the capillary radius profile from experimental data of the meniscus position l as a function of time t. This problem is central in diverse applications, such as the characterization of nanopore arrays or the design of passive transport in microfluidics; it is mathematically ill posed and has multiple solutions; i.e., capillaries with different geometries may produce the same imbibition kinematics. Here a suitable approach is proposed to solve this problem, which is based on measuring the imbibition kinematics in both tube directions. Capillary filling experiments to validate the calculation were made in a wide range of length scales: glass capillaries with a radius of around 150 μm and anodized alumina membranes with a pores radius of around 30 nm were used. The proposed method was successful in identifying the radius profile in both systems. Fundamental aspects also emerge in this study, notably the fact that the l(t)∝t1/2 kinematics (Lucas-Washburn relation) is not exclusive of uniform cross-sectional capillaries.

  12. Inverse problem of capillary filling.

    PubMed

    Elizalde, Emanuel; Urteaga, Ral; Koropecki, Roberto R; Berli, Claudio L A

    2014-04-01

    The inverse problem of capillary filling, as defined in this work, consists in determining the capillary radius profile from experimental data of the meniscus position l as a function of time t. This problem is central in diverse applications, such as the characterization of nanopore arrays or the design of passive transport in microfluidics; it is mathematically ill posed and has multiple solutions; i.e., capillaries with different geometries may produce the same imbibition kinematics. Here a suitable approach is proposed to solve this problem, which is based on measuring the imbibition kinematics in both tube directions. Capillary filling experiments to validate the calculation were made in a wide range of length scales: glass capillaries with a radius of around 150???m and anodized alumina membranes with a pores radius of around 30??nm were used. The proposed method was successful in identifying the radius profile in both systems. Fundamental aspects also emerge in this study, notably the fact that the l(t)?t1/2 kinematics (Lucas-Washburn relation) is not exclusive of uniform cross-sectional capillaries. PMID:24745427

  13. Filling of charged cylindrical capillaries.

    PubMed

    Das, Siddhartha; Chanda, Sourayon; Eijkel, J C T; Tas, N R; Chakraborty, Suman; Mitra, Sushanta K

    2014-10-01

    We provide an analytical model to describe the filling dynamics of horizontal cylindrical capillaries having charged walls. The presence of surface charge leads to two distinct effects: It leads to a retarding electrical force on the liquid column and also causes a reduced viscous drag force because of decreased velocity gradients at the wall. Both these effects essentially stem from the spontaneous formation of an electric double layer (EDL) and the resulting streaming potential caused by the net capillary-flow-driven advection of ionic species within the EDL. Our results demonstrate that filling of charged capillaries also exhibits the well-known linear and Washburn regimes witnessed for uncharged capillaries, although the filling rate is always lower than that of the uncharged capillary. We attribute this to a competitive success of the lowering of the driving forces (because of electroviscous effects), in comparison to the effect of weaker drag forces. We further reveal that the time at which the transition between the linear and the Washburn regime occurs may become significantly altered with the introduction of surface charges, thereby altering the resultant capillary dynamics in a rather intricate manner. PMID:25375597

  14. Carbonaceous cathode with enhanced wettability for aluminum production

    DOEpatents

    Keller, Rudolf; Gatty, David G.; Barca, Brian J.

    2003-09-09

    A method of preparing carbonaceous blocks or bodies for use in a cathode in an electrolytic cell for producing aluminum wherein the cell contains an electrolyte and has molten aluminum contacting the cathode, the cathode having improved wettability with molten aluminum. The method comprises the steps of providing a carbonaceous block and a boron oxide containing melt. The carbonaceous block is immersed in the melt and pressure is applied to the melt to impregnate the melt into pores in the block. Thereafter, the carbonaceous block is withdrawn from the melt, the block having boron oxide containing melt intruded into pores therein, the boron oxide capable of reacting with a source of titanium or zirconium or like metal to form titanium or zirconium diboride during heatup or operation of said cell.

  15. Impact of particle laden drops onto surfaces of various wettability

    NASA Astrophysics Data System (ADS)

    Grishaev, Viktor; Iorio, Carlo Saverio; Amirfazli, Alidad

    2013-11-01

    Understanding characteristics of the impact of complex drops (liquid and solid particles) onto substrates is important for many applications, e.g. for additive manufacturing. Complex drops (diameter ~ 3.8 mm) were produced using polyethylene microspheres dispersed in deionized water. Drop impact was investigated on substrates with different wettability (contact angles <5 and 95) using high-speed cameras and image processing methods. By varying speed of the drops (1.7 to 3.7 m/s), diameter of the particles (200 and 500 ?m) and particles volume fraction (0 to 35 %), the influence of these variables on the impact dynamics of the drop and the distribution of particles after the impact was studied. For hydrophilic substrate, drops with 200 ?m particles are arranged in a ring after the impact. For hydrophobic substrate, drops can split into several drops depending on drop velocity, size and volume fraction of particles. Also, the dynamics of drop spreading was elucidated.

  16. Evaluation of Reservoir Wettability and its Effect on Oil Recovery

    SciTech Connect

    Buckley, Jill S.

    1999-11-09

    This project has three main goals. The first is to achieve improved understanding of the surface and interfacial properties of crude oils and their interactions with mineral surfaces. The second goal is to apply the results of surface studies to improved predictions of oil production in laboratory experiments. Finally, we aim to use the results of this research to recommend ways to improve oil recovery by waterflooding. In order to achieve these goals, the mechanisms of wetting alteration must be explained. We propose a methodology for studying those mechanisms on mineral surfaces, then applying the results to prediction and observation of wetting alteration in porous media. Improved understanding of the underlying mechanisms will show when and how wettability in the reservoir can be altered and under what circumstances that alteration would be beneficial in terms of increased production of oil.

  17. Evaluation of Reservoir Wettability and its Effect on Oil Recovery

    SciTech Connect

    Jill S. Buckley

    1998-04-13

    This project has three main goals. The first is to achieve improved understanding of the surface and interfacial properties of crude oils and their interactions with mineral surfaces. The second goal is to apply the results of surface studies to improved predictions of oil production in laboratory experiments. Finally, we aim to use the results of this research to recommend ways to improve oil recovery by waterflooding. In order to achieve these goals, the mechanisms of wetting alteration must be explained. We propose a methodology for studying those mechanisms on mineral surfaces, then applying the results to prediction and observation of wetting alteration in porous media. Improved understanding of the underlying mechanisms will show when and how wettability in the reservoir can be altered and under what circumstances that alteration would be beneficial in terms of increased production of oil.

  18. Substrate wettability requirement for the direct transfer of graphene

    NASA Astrophysics Data System (ADS)

    Du, F.; Duan, H. L.; Xiong, C. Y.; Wang, J. X.

    2015-10-01

    The direct transfer method, wherein graphene is transferred from its growth metal to a soft substrate, is widely used to fabricate various devices, and the interfacial bonding condition between the substrate and the graphene is vital for transfer success. In this letter, we present a theoretical model to derive the wettability requirements of the soft substrate to sustain the direct transfer of graphene, and verify the theoretical analysis with experiments. We find that the surface energy components of the substrate have a crucial effect upon the graphene transfer, and that substrates possessing a strong polar surface energy are not suitable for transfer. The theoretical model predicts the critical water contact angle of the soft substrate for graphene transfer to be about 50, and the experiments measure it to be about 60. These results provide guidelines for choosing proper substrates to transfer graphene during the fabrication of graphene-based flexible devices.

  19. Methods and preliminary measurement results of liquid Li wettability

    SciTech Connect

    Zuo, G. Z. Hu, J. S.; Ren, J.; Sun, Z.; Yang, Q. X.; Li, J. G.; Zakharov, L. E.; Mansfield, D. K.

    2014-02-15

    A test of lithium wettability was performed in high vacuum (< 3 × 10{sup −4} Pa). High magnification images of Li droplets on stainless steel substrates were produced and processed using the MATLAB{sup ®} program to obtain clear image edge points. In contrast to the more standard “θ/2” or polynomial fitting methods, ellipse fitting of the complete Li droplet shape resulted in reliable contact angle measurements over a wide range of contact angles. Using the ellipse fitting method, it was observed that the contact angle of a liquid Li droplet on a stainless steel substrate gradually decreased with increasing substrate temperature. The critical wetting temperature of liquid Li on stainless steel was observed to be about 290 °C.

  20. Local wettability tuning with laser ablation redeposits on PDMS

    NASA Astrophysics Data System (ADS)

    van Pelt, Stijn; Frijns, Arjan; Mandamparambil, Rajesh; den Toonder, Jaap

    2014-06-01

    In this paper, we present a method to locally control the wettability behavior of PDMS surfaces by excimer laser ablation. In the ablation process, a micrometer scale roughness is formed in the irradiated regions while a nanometer scale roughness is formed by the redeposits surrounding the irradiated regions. The increase in surface roughness results in a change of the wettability behavior of the PDMS surface. By using a hexagonal pattern and tuning the patterning pitch, two different wetting behaviors were realized. A pitch smaller than 300 ?m resulted in a superhydrophobic surface with an advancing contact angle of ?adv = 165 and a receding contact angle of ?rec = 160. A pitch between 300 and 500 ?m resulted in a sticky superhydrophobic surface with ?adv = 120-150 and ?rec = 80. The contact angle hysteresis for the latter was larger than for untreated PDMS resulting in very sticky surfaces with high sliding angles. This gives the method great versatility since the two wetting behaviors are very different. By combining both behaviors, local surface features like pinning sites, non-wetting sites, barriers and guides can all be fabricated by a single method. As an application demonstrator of the method, we show that drops can be caught and released depending on size and tilting angle by creating slippery surfaces with sticky barriers. Additionally, the method is ideal for rapid prototyping as it consist of only a single step. It is a direct write method requiring no lithographic mask. Also the process works in ambient atmosphere, so it can be used for temperature or pressure sensitive applications.

  1. Separate effects of surface roughness, wettability, and porosity on the boiling critical heat flux

    NASA Astrophysics Data System (ADS)

    O'Hanley, Harry; Coyle, Carolyn; Buongiorno, Jacopo; McKrell, Tom; Hu, Lin-Wen; Rubner, Michael; Cohen, Robert

    2013-07-01

    The separate effects of surface wettability, porosity, and roughness on the critical heat flux (CHF) of water were examined using engineered surfaces. Values explored were 0, 5, 10, and 15 μm for Rz (roughness), <5°, ˜75°, and >110° for static contact angle (wettability), and 0 and 50% for pore volume fraction. The porous hydrophilic surface enhanced CHF by 50%-60%, while the porous hydrophobic surface resulted in a reduction of CHF by 97%. Wettability had little effect on the smooth non-porous surface CHF. Surface roughness (Ra, Rq, Rz) had no effect on CHF within the limit of this database.

  2. Biocompatible patterning of proteins on wettability gradient surface by thermo-transfer printing.

    PubMed

    Kim, Sungho; Ryu, Yong-Sang; Suh, Jeng-Hun; Keum, Chang-Min; Sohn, Youngjoo; Lee, Sin-Doo

    2014-08-01

    We develop a simple and biocompatible method of patterning proteins on a wettability gradient surface by thermo-transfer printing. The wettability gradient is produced on a poly(dimethylsiloxane) (PDMS)-modified glass substrate through the temperature gradient during thermo-transfer printing. The water contact angle on the PDMS-modified surface is found to gradually increase along the direction of the temperature gradient from a low to a high temperature region. Based on the wettability gradient, the gradual change in the adsorption and immobilization of proteins (cholera toxin B subunit) is achieved in a microfluidic cell with the PDMS-modified surface. PMID:25936059

  3. Experimental Studies of Surface-Driven Capillary Flow in PMMA Microfluidic Devices Prepared by Direct Bonding Technique and Passive Separation of Microparticles in Microfluidic Laboratory-On Systems

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Subhadeep; Banerjee, J. P.; Mathur, Ashish; Tweedie, M.; McLaughlin, J. A.; Roy, Susanta Sinha

    2015-05-01

    Proper bonding technique is investigated to achieve leakage-free surface-driven capillary flow in polymethylmethacrylate (PMMA) microfluidic devices. SU-8-based silicon stamp is fabricated by maskless lithography. This stamp is used to produce PMMA microchannel structure by hot embossing lithography. A direct bonding technique is mainly employed for leakage-free sealing inside PMMA microfluidic devices. The effect of surface wettability on surface-driven capillary flow is also investigated in PMMA microfluidic devices. The separation of polystyrene microparticles in PMMA laboratory-on-a-chip systems is investigated with the reduction of separation time by air dielectric barrier discharge (DBD) plasma processing of channel surfaces. This study is useful to fabricate the microfluidic laboratory-on-a-chip systems and to understand the surface-driven capillary flow.

  4. The responses to surface wettability gradients induced by chitosan nanofilms on microtextured titanium mediated by specific integrin receptors

    PubMed Central

    Park, Jung Hwa; Wasilewski, Christine E.; Almodovar, Noelia; Olivares-Navarrete, Rene; Boyan, Barbara D.; Tannenbaum, Rina; Schwartz, Zvi

    2013-01-01

    Microtexture and chemistry of implant surfaces are important variables for modulating cellular responses. Surface chemistry and wettability are connected directly. While each of these surface properties can influence cell response, it is difficult to decouple their specific contributions. To address this problem, the aims of this study were to develop a surface wettability gradient with a specific chemistry without altering micron scale roughness and to investigate the role of surface wettability on osteoblast response. Microtextured sandblasted/acid-etched (SLA, Sa = 3.1 μm) titanium disks were treated with oxygen plasma to increase reactive oxygen density on the surface. At 0, 2, 6, 10, and 24 h after removing them from the plasma, the surfaces were coated with chitosan for 30 min, rinsed and dried. Modified SLA surfaces are denoted as SLA/h in air prior to coating. Surface characterization demonstrated that this process yielded differing wettability (SLA0 < SLA2 < SLA10 < SLA24) without modifying the micron scale features of the surface. Cell number was reduced in a wettability-dependent manner, except for the most water-wettable surface, SLA24. There was no difference in alkaline phosphatase activity with differing wettability. Increased wettability yielded increased osteocalcin and osteoprotegerin production, except on the SLA24 surfaces. mRNA for integrins α1, α2, α5, β1, and β3 was sensitive to surface wettability. However, surface wettability did not affect mRNA levels for integrin α3. Silencing β1 increased cell number with reduced osteocalcin and osteoprotegerin in a wettability-dependent manner. Surface wettability as a primary regulator enhanced osteoblast differentiation, but integrin expression and silencing β1 results indicate that surface wettability regulates osteoblast through differential integrin expression profiles than microtexture does. The results may indicate that both microtexture and wettability with a specific chemistry have important regulatory effects on osseointegration. Each property had different effects, which were mediated by different integrin receptors. PMID:22835642

  5. Multifunctional commercially pure titanium for the improvement of bone integration: Multiscale topography, wettability, corrosion resistance and biological functionalization.

    PubMed

    Ferraris, Sara; Vitale, Alessandra; Bertone, Elisa; Guastella, Salvatore; Cassinelli, Clara; Pan, Jinshan; Spriano, Silvia

    2016-03-01

    The objects of this research are commercially pure titanium surfaces, with multifunctional behavior, obtained through a chemical treatment and biological functionalization. The explored surfaces are of interest for dental implants, in contact with bone, where several simultaneous and synergistic actions are needed, in order to get a fast and effective osseointegration. The here described modified surfaces present a layer of titanium oxide, thicker than the native one, with a multi-scale surface topography (a surface roughness on the nano scale, which can be overlapped to a micro or macro roughness of the substrate) and a high density of OH groups, that increase surface wettability, induce a bioactive behavior (hydroxyapatite precipitation in simulated body fluid) and make possible the grafting of biomolecules (alkaline phosphatase, ALP, in the present research). The surface oxide is an efficient barrier against corrosion, with passive behavior both with and without application of an external voltage. PMID:26706544

  6. Capillary pressure - saturation relations for supercritical CO2 and brine: Implications for capillary/residual trapping in carbonate reservoirs during geologic carbon sequestration

    NASA Astrophysics Data System (ADS)

    Wang, S.; Tokunaga, T. K.

    2014-12-01

    In geologic carbon sequestration (GCS), data on capillary pressure (Pc) - saturation (Sw) relations are routinely needed to appraise reservoir processes. Capillarity and its hysteresis have been often experimentally studied in oil-water, gas-water and three phase gas-oil-water systems, but fewer works have been reported on scCO2-water under in-situ reservoir conditions. Here, Pc-Sw relations of supercritical (sc) CO2 displacing brine, and brine rewetting the porous medium to trap scCO2 were studied to understand CO2 transport and trapping behavior in carbonate reservoirs under representative reservoir conditions. High-quality drainage and imbibition (and associated capillary pressure hysteresis) curves were measured under elevated temperature and pressure (45 C, 8.5 and 12 MPa) for scCO2-brine as well as at room temperature and pressure (23 C, 0.1 MPa) for air-brine in unconsolidated limestone and dolomite sand columns using newly developed semi-automated multistep outflow-inflow porous plate apparatus. Drainage and imbibition curves for scCO2-brine deviated from the universal scaling curves for hydrophilic interactions (with greater deviation under higher pressure) and shifted to lower Pc than predicted based on interfacial tension (IFT) changes. Augmented scaling incorporating differences in IFT and contact angle improved the scaling results but the scaled curves still did not converge onto the universal curves. Equilibrium residual trapping of the nonwetting phase was determined at Pc =0 during imbibition. The capillary-trapped amounts of scCO2 were significantly larger than for air. It is concluded that the deviations from the universal capillary scaling curves are caused by scCO2-induced wettability alteration, given the fact that pore geometry remained constant and IFT is well constrained. In-situ wettability alteration by reactive scCO2 is of critical importance and must be accounted for to achieve reliable predictions of CO2 behavior in GCS reservoirs.

  7. Pulmonary capillary pressure. A review.

    PubMed

    Ganter, C C; Ganter, C G; Jakob, S M; Takala, J

    2006-01-01

    Pulmonary capillary pressure (Pcap) is the predominant force that drives fluid out of the pulmonary capillaries into the interstitium. Increasing hydrostatic capillary pressure is directly proportional to the lung's transvascular filtration rate, and in the extreme leads to pulmonary edema. In the pulmonary circulation, blood flow arises from the transpulmonary pressure gradient, defined as the difference between pulmonary artery (diastolic) pressure and left atrial pressure. The resistance across the pulmonary vasculature consists of arterial and venous components, which interact with the capacitance of the compliant pulmonary capillaries. In pathological states such as acute respiratory distress syndrome, sepsis, and high altitude or neurogenic lung edema, the longitudinal distribution of the precapillary arterial and the postcapillary venous resistance varies. Subsequently, the relationship between Pcap and pulmonary artery occlusion pressure (PAOP) is greatly variable and Pcap can no longer be predicted from PAOP. In clinical practice, PAOP is commonly used to guide fluid therapy, and Pcap as a hemodynamic target is rarely assessed. This approach is potentially misleading. In the presence of a normal PAOP and an increased pressure gradient between Pcap and PAOP, the tendency for fluid leakage in the capillaries and subsequent edema development may substantially be underestimated. Tho-roughly validated methods have been developed to assess Pcap in humans. At the bedside, measurement of Pcap can easily be determined by analyzing a pressure transient after an acute pulmonary artery occlusion with the balloon of a Swan-Ganz catheter. PMID:16407804

  8. Research progress in TiB2 wettable cathode for aluminum reduction

    NASA Astrophysics Data System (ADS)

    Li, Jie; Lü, Xiao-Jun; Lai, Yan-Qing; Li, Qing-Yu; Liu, Ye-Xiang

    2008-08-01

    Titanium diboride wettable cathodes are regarded as ideal for aluminum reduction because of their excellent wettability with molten aluminum. The TiB2 inert wettable cathode materials for aluminum reduction may be divided into three groups: pure TiB2 ceramic cathode, TiB2 composite cathode, and TiB2 coating. This paper briefly describes international research progress on TiB2 inert wettable cathodes as well as problems faced, and concentrates on the activities of Central South University, Changsha, China, in researching the ambient-temperature solidified TiB2 cathode coating. At the same time, the results of the coating applied in many aluminum smelters in China are presented, and the pattern of cathode surface of 160 kA cells coated with the ambient-temperature-solidified TiB2 cathode coating after one year operation is discussed in comparison with the normal cells.

  9. Capillary flow enhancement in rectangular polymer microchannels with a deformable wall

    NASA Astrophysics Data System (ADS)

    Anoop, R.; Sen, A. K.

    2015-07-01

    We report the capillary flow enhancement in rectangular polymer microchannels, when one of the channel walls is a deformable polymer membrane. We provide detailed insight into the physics of elastocapillary interaction between the capillary flow and elastic membrane, which leads to significant improvements in capillary flow performance. As liquid flows by capillary action in such channels, the deformable wall deflects inwards due to the Young-Laplace pressure drop across the liquid meniscus. This, in turn, decreases the radius of curvature of the meniscus and increases the driving capillary pressure. A theoretical model is proposed to predict the resultant increase in filling speed and rise height, respectively, in deformable horizontal and vertical microchannels having large aspect ratios. A non-dimensional parameter J , which represents the ratio of the capillary force to the mechanical restoring force, is identified to quantify the elastocapillary effects in terms of the improvement in filling speed (for J >0.238 ) and the condition for channel collapse (J >1 ). The theoretical predictions show good agreement with experimental data obtained using deformable rectangular poly(dimethylsiloxane) microchannels. Both model predictions and experimental data show that over 15% improvement in the Washburn coefficient in horizontal channels, and over 30% improvement in capillary rise height in vertical channels, are possible prior to channel collapse. The proposed technique of using deformable membranes as channel walls is a viable method for capillary flow enhancement in microfluidic devices.

  10. Capillary filling under electro-osmotic effects in the presence of electromagneto-hydrodynamic effects

    NASA Astrophysics Data System (ADS)

    Desai, Nikhil; Ghosh, Uddipta; Chakraborty, Suman

    2014-06-01

    We report various regimes of capillary filling dynamics under electromagneto-hydrodynamic interactions, in the presence of electrical double layer effects. Our chosen configuration considers an axial electric field and transverse magnetic field acting on an electrolyte. We demonstrate that for positive interfacial potential, the movement of the capillary front resembles capillary rise in a vertical channel under the action of gravity. We also evaluate the time taken by the capillary front to reach the final equilibrium position for positive interfacial potential and show that the presence of a transverse magnetic field delays the time of travel of the liquid front, thereby sustaining the capillary motion for a longer time. Our scaling estimates reveal that the initial linear regime starts, as well as ends, much earlier in the presence of electrical and magnetic body forces, as compared to the corresponding transients observed under pure surface tension driven flow. We further obtain a long time solution for the capillary imbibition for positive interfacial potential, and derive a scaling estimate of the capillary stopping time as a function of the applied magnetic field and an intrinsic length scale delineating electromechanical influences of the electrical double layer. Our findings are likely to offer alternative strategies of controlling dynamical features of capillary imbibition, by modulating the interplay between electromagnetic interactions, electrical double layer phenomena, and hydrodynamics over interfacial scales.

  11. Reduced soil wettability can affect greenhouse gas fluxes

    NASA Astrophysics Data System (ADS)

    Urbanek, Emilia; Qassem, Khalid

    2015-04-01

    Soil moisture is known to be an important factor affecting the carbon (C) dynamics in soils including decomposition of organic matter and exchange of gases like CO2 and CH4 between the soil and the atmosphere. Most studies and process models looking at the soil C dynamics assume, however, that soils are easily wettable and water is relatively uniformly distributed within the soil pores. Most soils, however, do not wet spontaneously when dry or moderately moist, but instead exhibit some degree of soil water repellency (i.e. hydrophobicity), which can restrict infiltration and conductivity of water for weeks or months. This is world-wide occurring phenomenon which affects all soil textural types but is particularly common under permanent vegetation e.g. forest, grass and shrub vegetation. Soil water repellency is most profound during drier seasons, when the soil moisture content is relatively low. Although prolonged contact with water can gradually decrease water repellency, some soils do not recover to being completely wettable even after very wet winter months or substantial rainfall events. It has been recognized that with the predicted climatic changes the phenomenon of soil water repellency will become even more pronounced and severe, additionally it may occur in the areas and climatic zones where the effect have not been currently recognized. One of the main implications of soil water repellency is restricted water infiltration and reduced conductivity, which results in reduced soil water availability for plants and soil biota, even after prolonged periods of rainfall. As the process of C mineralization and consequently CO2 efflux from soil is driven by the accessibility of organic matter to decomposing organisms, which in turn is directly dependent on (i) soil moisture and (ii) soil temperature it is, therefore hypothesised that carbon decomposition and CO2 efflux in water repellent soils will also be affected when soil in the water repellent state. The CO2 fluxes will, however, increase once the soil switches to wettable conditions. In a similar way the water repellency affects soil CH4 fluxes favouring the process of oxidation by methanotrophs in water repellent soils. The results of the interdisciplinary study of CH4 and CO2 fluxes from water repellent soils in field and laboratory conditions will be presented. The study sites located in the Netherlands and United Kingdom and include the areas under climatic drought and temperature simulations in the heath-land areas, as well as the sites under natural climatic conditions under grassland and forest land use in the temperate climate. The results available to date provide a strong indication that C mineralization is reduced in water repellent soil, and, given that the total plant biomass in naturally water repellent soil-vegetation systems appears unaffected, this could enhance soil C sequestration on the long term.

  12. Non-Aqueous Capillary Electrophoresis

    NASA Astrophysics Data System (ADS)

    Szumski, Michał; Buszewski, Bogusław

    Non-aqueous capillary electrophoresis and capillary electrochromatography are special variants of these techniques. Here, organic solvents or their mixtures with or without dissolved electrolytes are used as separation buffer or mobile phase, respectively. The most important features of non-aqueous systems are: better solubility of more hydrophobic ionic substances (many natural products) than in water, much less current and Joule heating allows for using highly concentrated buffers and/or larger capillary internal diameters, polar interactions are enhanced in organic solvents which is often highly advantageous in chiral separation systems. This chapter presents most frequently used solvents, their properties, as well as shows pH* scale which is often used in non-aqueous systems.

  13. Paramecium swimming in capillary tube

    NASA Astrophysics Data System (ADS)

    Jana, Saikat; Um, Soong Ho; Jung, Sunghwan

    2012-04-01

    Swimming organisms in their natural habitat need to navigate through a wide range of geometries and chemical environments. Interaction with boundaries in such situations is ubiquitous and can significantly modify the swimming characteristics of the organism when compared to ideal laboratory conditions. We study the different patterns of ciliary locomotion in glass capillaries of varying diameter and characterize the effect of the solid boundaries on the velocities of the organism. Experimental observations show that Paramecium executes helical trajectories that slowly transition to straight lines as the diameter of the capillary tubes decreases. We predict the swimming velocity in capillaries by modeling the system as a confined cylinder propagating longitudinal metachronal waves that create a finite pressure gradient. Comparing with experiments, we find that such pressure gradient considerations are necessary for modeling finite sized ciliary organisms in restrictive geometries.

  14. A review on the wettability of dental implant surfaces I: theoretical and experimental aspects.

    PubMed

    Rupp, Frank; Gittens, Rolando A; Scheideler, Lutz; Marmur, Abraham; Boyan, Barbara D; Schwartz, Zvi; Geis-Gerstorfer, Jrgen

    2014-07-01

    The surface wettability of biomaterials determines the biological cascade of events at the biomaterial/host interface. Wettability is modulated by surface characteristics, such as surface chemistry and surface topography. However, the design of current implant surfaces focuses mainly on specific micro- and nanotopographical features, and is still far from predicting the concomitant wetting behavior. There is an increasing interest in understanding the wetting mechanisms of implant surfaces and the role of wettability in the biological response at the implant/bone or implant/soft tissue interface. Fundamental knowledge related to the influence of surface roughness (i.e. a quantification of surface topography) on titanium and titanium alloy surface wettability, and the different associated wetting regimes, can improve our understanding of the role of wettability of rough implant surfaces on the biological outcome. Such an approach has been applied to biomaterial surfaces only in a limited way. Focusing on titanium dental and orthopaedic implants, the present study reviews the current knowledge on the wettability of biomaterial surfaces, encompassing basic and applied aspects that include measurement techniques, thermodynamic aspects of wetting and models predicting topographical and roughness effects on the wetting behavior. PMID:24590162

  15. Wettability of silane-treated glass slides as determined from X-ray photoelectron spectroscopy

    SciTech Connect

    Araujo, Y.C.; Toledo, P.G.; Leon, V.; Gonzalez, H.Y.

    1995-12-15

    The wettability and stability of silane-treated substrates are central in many processes of industrial and environmental interest. Here, the authors bring the capability of X-ray photoelectron spectroscopy (XPS) to bear on the wettability evaluation of treated glass. For a suite of silane-treated slides the authors investigate the relationship between wettability and surface composition as determined from XPS. The adhesion behavior and contact angle of mineral oil on brine-covered surfaces are used here as surface wettability indicators. The XPS spectra of silanes and silane-treated glass slides indicate that silicon species of the kind Si-CH exhibit a well-defined binding energy which differs from that of the Si-O species of the glass. The presence of the Si-CH species reveals glass surfaces that have been rendered hydrophobic by chemisorption of organic matter. The surface carbon content as determined from XPS correlates strongly with the equilibrium contact angle, contact angle hysteresis, adhesion behavior, and wettability state. This correlation can be used to rapidly determine the wettability of treated glass.

  16. Adhesion of mouse fibroblasts on hexamethyldisiloxane surfaces with wide range of wettability.

    PubMed

    Wei, Jianhua; Yoshinari, Masao; Takemoto, Shinji; Hattori, Masayuki; Kawada, Eiji; Liu, Baolin; Oda, Yutaka

    2007-04-01

    Surface wettability is an important physicochemical property of biomaterials, and it would be more helpful for understanding this property if a wide range of wettability are employed. This study focused on the effect of surface wettability on fibroblast adhesion over a wide range of wettability using a single material without changing surface topography. Plasma polymerization with hexamethyldisiloxane followed by oxygen (O2)-plasma treatment was employed to modify the surfaces. The water contact angle of sample surfaces varied from 106 degrees (hydrophobicity) to almost 0 degrees (super-hydrophilicity). O2 functional groups were introduced on polymer surfaces during O2-plasma treatment. The cell attachment study confirmed that the more hydrophilic the surface, the more fibroblasts adhered in the initial stage that includes super-hydrophilic surfaces. Cells spread much more widely on the hydrophilic surfaces than on the hydrophobic surfaces. There was no significant difference in fibroblast proliferation, but cell spreading was much greater on the hydrophilic surfaces. The fibronectin adsorbed much more on a hydrophilic surface while albumin dominated on a hydrophobic surface in a competing mode. These findings suggest the importance of the surface wettability of biomaterials on initial cell attachment and spreading. The degree of wettability should be taken into account when a new biomaterial is to be employed. PMID:16924616

  17. Wettability measurement apparatus for porous material using the modified Washburn method

    NASA Astrophysics Data System (ADS)

    Thakker, Manish; Karde, Vikram; Shah, Dinesh O.; Shukla, Premal; Ghoroi, Chinmay

    2013-12-01

    In this work a cost-effective instrument for measuring the wettability of powder materials was designed and developed, which works on the modified Washburn method. The instrument measures the mass gain against time due to penetration of the liquid into the powder materials using a microbalance and LabVIEW-based data acquisition system. The wettability characteristic of different powders was determined from the contact angle using the modified Washburn equation. To demonstrate the performance of the developed instrument, the wettability of as-received corn starch and nano-coated corn starch powders was estimated with water as a test liquid. The corn starch powders coated with hydrophilic grade (Aerosil 200P) and hydrophobic grade (Aerosil R972) nanoparticles at different coating levels showed expected changes in their contact angle. Some of the results were also verified against the available standard instrument for wettability measurement and found to be consistent. The present configuration of the instrument costs about 500 US which is 15 to 20 times less than the available advanced models. The developed instrument is thus a cost-effective solution for wettability measurement which can be used for materials in food processing, pharmaceuticals, horticulture, textile manufacturing, civil engineering etc. The developed instrument is expected to help many small scale industries or research labs who cannot afford an expensive instrument for wettability studies.

  18. Laser processing of metallic biomaterials: An approach for surface patterning and wettability control

    NASA Astrophysics Data System (ADS)

    Razi, Sepehr; Mollabashi, Mahmoud; Madanipour, Khosro

    2015-12-01

    Q -switched Nd:YAG laser is used to manipulate the surface morphology and wettability characteristic of 316L stainless steel (SS) and titanium biomaterials. Water and glycerol are selected as wettability testing liquids and the sessile drop method is used for the contact angle measurements. Results indicate that on both of the metals, wettability toward water improves significantly after the laser treatment. Different analyses including the study of the surface morphology, free energy and oxidation are assessed in correlation with wettability. Beside the important role of the laser-induced surface patterns, the increase in the surface roughness, oxygen content and the polar component of the surface energy, are detected as the most important physical and chemical phenomena controlling the improvement in the wettability. However, all the processed hydrophilic surfaces that are exposed to air become hydrophobic over time. The time dependency of the surface wettability is related to the chemical activities on the treated surfaces and the reduction of oxygen/carbon (O/C) ratio on them. The behavior is further studied with investigating the effect of the keeping environment and changes of the components of the surface tension. Results show that the pulsed laser treatment is a versatile approach to create either hydrophobic or super hydrophilic surfaces for industrial and medical applications.

  19. A Review on the Wettability of Dental Implant Surfaces: Theoretical and Experimental Aspects

    PubMed Central

    Rupp, Frank; Gittens, Rolando A.; Scheideler, Lutz; Marmur, Abraham; Boyan, Barbara D.; Schwartz, Zvi; Geis-Gerstorfer, Jürgen

    2014-01-01

    The surface wettability of biomaterials determines the biological cascade of events at the biomaterial/host interface. Wettability is modulated by surface characteristics, such as surface chemistry and surface topography. However, the design of current implant surfaces focuses mainly on specific micro- and nanotopographical features and is still far from predicting the concomitant wetting behavior. There is an increasing interest in understanding the wetting mechanisms of implant surfaces and the role of wettability on the biological response at the implant/bone or implant/soft tissue interface. Fundamental knowledge related to the influence of surface roughness (i.e., a quantification of surface topography) on titanium and titanium alloy surface wettability, and the different associated wetting regimes, can improve our understanding of the role of wettability of rough implant surfaces on the biological outcome. Such an approach has been applied to biomaterial surfaces only in a limited way. Focusing on titanium dental and orthopaedic implants, the present study reviews the current knowledge on the wettability of biomaterial surfaces, encompassing basic and applied aspects that include measurement techniques, thermodynamic aspects of wetting, and models predicting topographical and roughness effects on the wetting behavior. PMID:24590162

  20. Surface energy and wettability of van der Waals structures

    NASA Astrophysics Data System (ADS)

    Annamalai, Meenakshi; Gopinadhan, Kalon; Han, Sang A.; Saha, Surajit; Park, Hye Jeong; Cho, Eun Bi; Kumar, Brijesh; Patra, Abhijeet; Kim, Sang-Woo; Venkatesan, T.

    2016-03-01

    The wetting behaviour of surfaces is believed to be affected by van der Waals (vdW) forces; however, there is no clear demonstration of this. With the isolation of two-dimensional vdW layered materials it is possible to test this hypothesis. In this paper, we report the wetting behaviour of vdW heterostructures which include chemical vapor deposition (CVD) grown graphene, molybdenum disulfide (MoS2) and tungsten disulfide (WS2) on few layers of hexagon boron nitride (h-BN) and SiO2/Si. Our study clearly shows that while this class of two-dimensional materials are not completely wetting transparent, there seems to be a significant amount of influence on their wetting properties by the underlying substrate due to dominant vdW forces. Contact angle measurements indicate that graphene and graphene-like layered transitional metal dichalcogenides invariably have intrinsically dispersive surfaces with a dominating London-vdW force-mediated wettability.The wetting behaviour of surfaces is believed to be affected by van der Waals (vdW) forces; however, there is no clear demonstration of this. With the isolation of two-dimensional vdW layered materials it is possible to test this hypothesis. In this paper, we report the wetting behaviour of vdW heterostructures which include chemical vapor deposition (CVD) grown graphene, molybdenum disulfide (MoS2) and tungsten disulfide (WS2) on few layers of hexagon boron nitride (h-BN) and SiO2/Si. Our study clearly shows that while this class of two-dimensional materials are not completely wetting transparent, there seems to be a significant amount of influence on their wetting properties by the underlying substrate due to dominant vdW forces. Contact angle measurements indicate that graphene and graphene-like layered transitional metal dichalcogenides invariably have intrinsically dispersive surfaces with a dominating London-vdW force-mediated wettability. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06705g

  1. Weight-controlled capillary viscometer

    NASA Astrophysics Data System (ADS)

    Digilov, Rafael M.; Reiner, M.

    2005-11-01

    The draining of a water column through a vertical discharge capillary tube is examined with the aid of a force sensor. The change of the mass of the liquid in the column with time is found to be not purely exponential as implied by Poiseuille's law. Using observed residuals associated with a kinetic energy correction, an approximate formula for the mass as a function of time is derived and excellent agreement with experimental data is attained. These results are verified by a viscosity test of distilled water at room temperature. A simple and inexpensive weight-controlled capillary viscometer is proposed that is especially suitable for undergraduate physics and chemistry laboratories.

  2. Nonsteady Flow in Capillary Tubes

    NASA Astrophysics Data System (ADS)

    Hara, Ayako

    2000-03-01

    Surface phenomena in the field of electron devices and the problem of how long. It takes plants to absorb water during their growth in hydroponic cultivation is attraching the attention of riseachers. However, the related study of non-steady flow in capillary tubes has a number of issues that require investigation. In response to this situation, we made attempted to assess nonsteady fiow in capillary tubes, the liquid rise time and other issues, using a motion equation that takes factors including the friction force of the tube and the surface tension into consideration.

  3. Surface wettability plays a significant role in gecko adhesion underwater

    PubMed Central

    Stark, Alyssa Y.; Badge, Ila; Wucinich, Nicholas A.; Sullivan, Timothy W.; Niewiarowski, Peter H.; Dhinojwala, Ali

    2013-01-01

    Although we now have thousands of studies focused on the nano-, micro-, and whole-animal mechanics of gecko adhesion on clean, dry substrates, we know relatively little about the effects of water on gecko adhesion. For many gecko species, however, rainfall frequently wets the natural surfaces they navigate. In an effort to begin closing this gap, we tested the adhesion of geckos on submerged substrates that vary in their wettability. When tested on a wet hydrophilic surface, geckos produced a significantly lower shear adhesive force (5.4 1.33 N) compared with a dry hydrophilic surface (17.1 3.93 N). In tests on an intermediate wetting surface and a hydrophobic surface, we found no difference in shear adhesion between dry and wet contact. Finally, in tests on polytetrafluoroethylene (PTFE), we found that geckos clung significantly better to wet PTFE (8.0 1.09 N) than dry PTFE (1.6 0.66 N). To help explain our results, we developed models based on thermodynamic theory of adhesion for contacting surfaces in different media and found that we can predict the ratio of shear adhesion in water to that in air. Our findings provide insight into how geckos may function in wet environments and also have significant implications for the development of a synthetic gecko mimic that retains adhesion in water. PMID:23576727

  4. AFM study of mineral wettability with reservoir oils.

    PubMed

    Kumar, K; Dao, E; Mohanty, K K

    2005-09-01

    Wettability plays a key role in determining fluid distributions and consequently the multiphase flow and transport in petroleum reservoirs. Many crude oils have polar organic components that collect at oil-water interfaces and can adsorb onto the mineral surface if the brine film breaks, rendering the medium oil-wet or mixed-wet. Mica and silica surfaces have been aged with brine and crude oils to induce oil component adsorption. Bulk oil is eventually replaced by water in these experiments by washing with common solvents without ever drying the mineral surface. The organic deposit on the mineral surface is studied by atomic force microscopy in the tapping mode under water. Drying the surface during the removal of bulk oil induces artifacts; it is essential to keep the surface wet at all times before atomic force microscopy or contact angle measurement. As the mean thickness of the organic deposit increases, the oil-water contact angle increases. The organic deposits left behind after extraction of oil by common aromatic solvents used in core studies, such as toluene and decalin, are thinner than those left behind by non-aromatic solvents, such as cyclohexane. The force of adhesion with a probe sphere for minerals aged with just the asphaltene fraction is similar to that of the whole oil. The force of adhesion for the minerals aged with just the resin fraction is the highest of all SARA (saturates, aromatics, resins, and asphaltenes) fractions. PMID:16009229

  5. Biphilicity and Superbiphilicity for Wettability Control of Multiphase Heat Transfer

    NASA Astrophysics Data System (ADS)

    Attinger, Daniel; Betz, Amy Rachel; Schutzius, T. M.; Jenkins, J.; Kim, C.-J.; Megaridis, C. M.

    2012-11-01

    Multiphase energy transport, such as in boiling, suggests contradictory requirements on the wettability of the solid surfaces coming into contact with the working fluid. On the one hand, a hydrophobic wall promotes nucleation. On the other hand, a hydrophilic wall promotes water contact and enhances the critical heat flux. An analogous situation appears in the opposite thermodynamic process, i.e. condensation. These apparently contradictory requirements can be accommodated with biphilic surfaces, which juxtapose hydrophilic and hydrophobic regions. Biphilic surfaces were first manufactured in 1964 by Young and Hummel, who sprayed Teflon drops onto a smooth steel surface: they showed enhanced heat transfer coefficient during boiling of water. Our recent work has revisited the manufacturing of biphilic surfaces using micro- and nanofabrication processes (Betz et al. 2010, Schutzius et al. 2012); for instance, we fabricated the first superbiphilic surfaces, which juxtapose superhydrophobic and superhydrophilic areas. Using these surfaces, we measured significant enhancement during pool boiling of both the heat transfer coefficient and the critical heat flux. This enhanced performance can be explained by the inherent ability of the surfaces to control multiphase flow, decreasing nucleation energies and shaping drops, bubbles and jets, to maximize transport and prevent instabilities.

  6. Surface energy and wettability of van der Waals structures.

    PubMed

    Annamalai, Meenakshi; Gopinadhan, Kalon; Han, Sang A; Saha, Surajit; Park, Hye Jeong; Cho, Eun Bi; Kumar, Brijesh; Patra, Abhijeet; Kim, Sang-Woo; Venkatesan, T

    2016-03-01

    The wetting behaviour of surfaces is believed to be affected by van der Waals (vdW) forces; however, there is no clear demonstration of this. With the isolation of two-dimensional vdW layered materials it is possible to test this hypothesis. In this paper, we report the wetting behaviour of vdW heterostructures which include chemical vapor deposition (CVD) grown graphene, molybdenum disulfide (MoS2) and tungsten disulfide (WS2) on few layers of hexagon boron nitride (h-BN) and SiO2/Si. Our study clearly shows that while this class of two-dimensional materials are not completely wetting transparent, there seems to be a significant amount of influence on their wetting properties by the underlying substrate due to dominant vdW forces. Contact angle measurements indicate that graphene and graphene-like layered transitional metal dichalcogenides invariably have intrinsically dispersive surfaces with a dominating London-vdW force-mediated wettability. PMID:26910437

  7. Development of functional polymer surfaces with controlled wettability.

    PubMed

    Anastasiadis, Spiros H

    2013-07-30

    There is a demand for surfaces with new functional properties in almost all industrial branches. During the next few years, research input will be required for the development of coatings exhibiting an easy-to-clean or self-cleaning ability, switchability so that they can act as sensors/actuators, and defined tribological/mechanical properties and long-term stability. To achieve such behavior, the development of new advanced functional coatings that exhibit the proper chemistry and surface structure is necessary. In this Feature Article, we provide a review of the research activities in our laboratory on the development of functional and, especially, reversibly switchable polymer surfaces where the emphasis is on controlling their wettability. We will first discuss the fabrication of superhydrophobic surfaces by hierarchically micro- and nanostructuring a substrate surface with an ultrafast laser followed by appropriate hydrophobization. Then, we will summarize the development of surfaces that can alter their wetting behavior in response to changes in external stimuli such as humidity and light illumination. Finally, we will present our investigations on utilizing responsive (organic) coatings on hierarchically roughened substrates for the development of surfaces, which would be able to switch reversibly from superhydrophilic to superhydrophobic and water-repellent in response to an external stimulus (in this case, pH). PMID:23789943

  8. Wettability of naturally aged silicone and EPDM composite insulators

    SciTech Connect

    Gubanski, S.M. ); Vlastos, A.E. )

    1990-07-01

    This paper reports the wettability of aged surfaces and of the bulk of naturally aged silicone and EPDM insulator housings and of silicone elastomer insulator coatings studied. The samples were taken either directly from the insulators or treated by exposing them to corona discharges and/or to saline pollution. The results show that the contact angles of the silicone rubber insulator surfaces are larger than the contact angles of the RTV silicone rubber coating and of the EPDM rubber insulator surfaces, especially when the surfaces are aged. When the insulators were exposed to corona discharges, the contact angles of the silicone rubber insulators are reduced but after the exposure they recover with time. The contact angles of the EPDM rubber insulators, however, after the exposure, continue to reduce. When exposed to artificial saline pollution, the silicone rubber insulators show a limited recovery of their contact angles with time, while, when exposed to corona discharge, they show a recovery of the contact angle after the exposure. The time for recovery is dependent on the exposure time to the corona discharges.

  9. Particle trajectories in linear periodic capillary and capillary-gravity water waves.

    PubMed

    Henry, David

    2007-09-15

    Surface tension plays a significant role as a restoration force in the setting of small-amplitude waves, leading to pure capillary and gravity-capillary waves. We show that within the framework of linear theory, the particle paths in a periodic gravity-capillary or pure capillary wave propagating at the surface of water over a flat bed are not closed. PMID:17360262

  10. Multiplexed fluorescence detector system for capillary electrophoresis

    DOEpatents

    Yeung, Edward S. (Ames, IA); Taylor, John A. (Nevada, IA)

    1996-03-12

    A fluorescence detection system for capillary electrophoresis is provided wherein the detection system can simultaneously excite fluorescence and substantially simultaneously monitor separations in multiple capillaries. This multiplexing approach involves laser irradiation of a sample in a plurality of capillaries through optical fibers that are coupled individually with the capillaries. The array is imaged orthogonally through a microscope onto a charge-coupled device camera for signal analysis.

  11. Multiplexed fluorescence detector system for capillary electrophoresis

    DOEpatents

    Yeung, Edward S. (Ames, IA); Taylor, John A. (Nevada, IA)

    1994-06-28

    A fluorescence detection system for capillary electrophoresis is provided wherein the detection system can simultaneously excite fluorescence and substantially simultaneously monitor separations in multiple capillaries. This multiplexing approach involves laser irradiation of a sample in a plurality of capillaries through optical fibers that are coupled individually with the capillaries. The array is imaged orthogonally through a microscope onto a charge-coupled device camera for signal analysis.

  12. Multiplexed fluorescence detector system for capillary electrophoresis

    DOEpatents

    Yeung, E.S.; Taylor, J.A.

    1994-06-28

    A fluorescence detection system for capillary electrophoresis is provided wherein the detection system can simultaneously excite fluorescence and substantially simultaneously monitor separations in multiple capillaries. This multiplexing approach involves laser irradiation of a sample in a plurality of capillaries through optical fibers that are coupled individually with the capillaries. The array is imaged orthogonally through a microscope onto a charge-coupled device camera for signal analysis. 14 figures.

  13. Multiplexed fluorescence detector system for capillary electrophoresis

    DOEpatents

    Yeung, E.S.; Taylor, J.A.

    1996-03-12

    A fluorescence detection system for capillary electrophoresis is provided wherein the detection system can simultaneously excite fluorescence and substantially simultaneously monitor separations in multiple capillaries. This multiplexing approach involves laser irradiation of a sample in a plurality of capillaries through optical fibers that are coupled individually with the capillaries. The array is imaged orthogonally through a microscope onto a charge-coupled device camera for signal analysis. 14 figs.

  14. Ash wettability conditions splash erosion in the postfire

    NASA Astrophysics Data System (ADS)

    Gordillo-Rivero, Ángel J.; de Celis, Reyes; García-Moreno, Jorge; Jiménez-Compán, Elizabeth; Alanís, Nancy; Cerdà, Artemi; Pereira, Paulo; Zavala, Lorena M.; Jordán, Antonio

    2015-04-01

    1. INTRODUCTION Soil sustainability and recovery after fire depend on physical, chemical and biological processes and fire severity (Neary et al., 1999; Mataix-Solera and Guerrero, 2007). Fire effects on soils are divided in two types: direct effects, as a consequence of combustion and temperature reached and indirect effects (Neary et al., 1999) as consequence of changes in other ecosystem components, such as decrease in vegetal coverage or ash and partially burned litter contribution including changes in flora (Pausas and Verdú, 2005; Trabaud, 2000). Low intensity fires, during which high temperatures are not reached, affect vegetal coverage but will not cause major impacts on soil. In contrast, prolonged, recurrent, or high-intensity fires may cause important impacts on the soil system functioning (De Celis et al., 2013; DeBano, 1991; Mataix-Solera et al., 2009; Zavala et al., 2014), aggregation (Mataix-Solera et al., 2011), organic matter content and quality (Sevink et al., 1989), water repellency (DeBano, 2000; Doerr et al., 2000), soil nutrients (Stark, 1977), soil erosion (Larsen et al., 2009) and others. In these cases, the restoration period of the initial conditions can be very long and changes may become permanent (DeBano, 1991). During combustion, fuel (biomass, necromass and soil organic matter) is transformed in materials with new physical and chemical properties. After burn, the soil surface is covered by a layer of ash and charred organic residues. Ash has important ecological, hydrological and geomorphological effects, even after being rearranged or mobilized by runoff or wind (Bodí et al., 2014). Ash properties will depend on the burned species, the amount of affected biomass, fuel flammability and structure, temperature and the residence time of thermal peaks (Pereira et al., 2009). Some studies have emphasized the role of ash on soil protection during the after fire period, in which the vegetable coverage could be drastically decreased (Cerdà and Doerr, 2008; Woods and Balfour, 2008; Zavala et al., 2009). The presence of an ash layer may be ephemeral, as it often is quickly removed or redistributed by water and wind erosion, animals or traffic (Zavala et al., 2009a). Many authors have observed that the capacity of ash to protect soil depends on properties as the topography, the meteorological conditions and the thickness of ash coverage (Cerdà and Doerr, 2008; Pereira et al., 2013; Woods and Balfour, 2010; Zavala et al., 2009). Taking this into account, in this study we hypothesized that the wettability / hydrophobicity of the ash layer may have a significant effect on the soil response to splash erosion. Therefore, the aim of this study is to evaluate the dispersion of sediments produced by the impact of raindrops in function of ash wettability after a prescribed fire at plot scale. 2. MATERIAL AND METHODS In 20 November 2012, a prescribed fire was carried out in an area located in the public mount "Las Navas", near Almaden de la Plata, Sevilla (approx. 37° 50' 44.44'' N / 6° 3' 7.44''W and 428 masl). Soils are acidic and shallow, developed from acidic metamorphic rocks (schists, slates and pyrophyllites). Vegetation is dominated by shrub legumes (Calicotome villosa and several species of Ulex and Genista). The experimental area was framed and plowed to eliminate the risk of fire spreading during the experiment. Previously to burn, level staffs were installed for determination of flame height. The temperature reached in the soil was monitored during the fire by a set of six thermocouples which were buried in soil (2 cm depth) and connected to a data-logger for monitoring the topsoil temperature every 60 s. The environmental conditions were also monitored during the experiment by a mobile weather station. At the moment of the ignition, the temperature was around 20 °C and the wind speed was near 0.0 m/s. After ignition, the experimental area was allowed to burn during 2.5 h. During burning, flames reached 200 cm height, although thermal peaks recorded 2 cm depth were relatively low (not surpassing 80 °C). After burning, the soil surface was covered by a pattern of white and black ash, indicating varying degrees of fire severity, and areas covered by water repellent or hydrophilic ash were selected using the ethanol percentage test (EPT). The EPT provides an indirect measurement of the surface tension of the ground and, therefore, indicates the intensity of soil water repellency and is based on the different surface tension of a number of standardized solutions of ethanol in water. The procedure consists in applying drops (0.05 mL) of different ethanol solutions with different concentrations onto the surface of the ash layer observing if infiltration occurs in a period that not exceed 5 s (Jordán et al., 2010) . Every drop is allowed to fall from a distance not bigger than 15 mm to avoid the excess of kinetic energy that can affect infiltration. Applying drops with decreasing surface tension (that is, with concentrations of increasing ethanol) until a drop resists the infiltration allows the classification of the ground in a particular class of surface tension between two concentrations of ethanol: that in which infiltration occurs immediately (in less than 5 s) and the above solution of weaker concentration. Thus, it is assumed that solution whose drop is infiltrated within the first 5 s after application has a lower surface tension than soil surface. Fifteen representative points were selected at wettable or water-repellent ash zone. At each selected point, surrounded by white/wettable or dark/water-repellent ash to a minimum distance of 0.5 m, splash sediment collection device was installed. This system consist on a couple of funnels (100 mm in diameter) arranged one inside the other, with a paper filter beween both. Each device was inserted in soil until only 10 mm protruding the ground surface in order to avoid capturing runoff sediments. Sediments collected at each point of study were collected monthly and determined gravimetrically after oven drying between November 2012 and May 2013. 3. RESULTS AND DISCUSSION Depending on the intensity of the water repellency, the ash layer fluctuated between wettable and very strongly water repellent. The ash has a high permeability and water storage. However, its hydrophilic character has been emphasized rarely (Cerdà and Doerr, 2008). Different authors have described hydrophobic behaviors depending on the burned vegetation such as oak (Gabet and Sternberg, 2008) or pine forest (Stark, 1977) in the United States, eucalyptus forest in Australia (Khanna et al., 1996 ) or Mediterranean tree and shrub species in Spain (Bodí et al., 2011). In the latter case, Bodí et al. (2011) observed that ash has different properties depending on the combustion conditions, organic carbon content and color. This variability of behavior agrees with the results obtained in the present work. Significant differences between splash erosion from wettable and water-repellent ash zones were found (p < 0.0001). In the water-repellent ash zone, large differences were found among samples. The amount of sediment displaced by splash increased rapidly up to 264.10% (from 3.90 ± 0.44 to 14.20 ± 1.75 g) during the first four months after burn (November 2012 - February 2013). In contrast, during the last three months (March - May 2013), the amount of displaced sediments remained high, but with low growing rate (28.11%, from 16.97 ± 1.66 to 21.74 ± 3.27 g). In the wettable ash zone, the amount of sediment displaced was much smaller, with mean values between 1.29 (November 2012) and 6.14 g (May 2013). During the first two sampling dates after burn, data did not differ significantly among sites (1.38 ± 0.18 g on average), but the amount of sediment collected grew slowly during the experimental period between 3.06 ± 0.39 and 6.14 ± 0.69 g (January - May 2013). Several authors have suggested that ash acts protecting soil from the direct impact of raindrops and thus reduce sediment dispersion by splash (Cerdà and Doerr, 2008, Larsen et al, 2009; Woods and Balfour, 2008, Zavala et al, 2009). However, there is very little information about the effect of hydrophobicity on splash erosion. In a rainfall simulation experiment under laboratory conditions, Bodí et al. (2012) observed that splash erosion was at least two times higher in samples of water repellent soil than in hydrophilic soil, but no differences in ash loss or thickness of ash layer were observed. 4. CONCLUSIONS Our results highlight the role played by ash water repellency and the influence of burn severity on the development of a pattern of splash erosion intensities. Splash erosion was reduced in one order of magnitude on wettable ash zones. In contrast, the presence of a water-repellent ash layer increases the mobilization of sediments at plot scale. Further research should focus on the impacts of ash wettability on splash erosion at hillslope scale in the post fire. REFERENCES Bodí MB, Doerr SH, Cerdà A, Mataix-Solera J. 2012. Hydrological effects of a layer of vegetation ash on underlying wettable and water repellent soil. Geoderma 191, 14-23. Bodí MB, Martin DA, Balfour VN, Santín C, Doerr SJ, Pereira P, Cerdà A. Mataix-Solera J. 2014. Wildland fire ash: Production, composition and eco-hydro-geomorphic effects. Earth-Sciece Reviews 130, 103-127. Cerdà A, Doerr, SH. 2008. The effect of ash and needle cover on surface runoff and erosion in the immediate post-fire period. Catena 74, 256-263. De Celis R, Jordán A, Zavala LM. 2013. Efectos del fuego en las propiedades biológicas, físicas y químicas del suelo. In: Bento-Gonçalves A, Vieira A (Eds.), Grandes incêndios florestais, erosão, degradação e medidas de recuperação dos solos. Núcleo de Investigação en Geografia e Planeamento (NIGP), Universidade do Minho. Guimaraes. Pp.: 145-160. DeBano LF. 1991. The effect of fire on soil. In: Harvey AE; Neuenschwander LF.(Eds.), Management and productivity of western-montane forest soils. General Technical Report INT-280. Intermountain Forest and Range Experimental Station, United States Department of Agriculture, Forest Service. Ogden, UT. DeBano LF. 2000. Water repellency in soils: a historical overview. Journal of Hydrology 231-232, 4-32. Doerr SH, Shakesby RA, Walsh RPD. 2000. Soil water repellency: its causes, characteristics and hydro-geomorphological significance. Earth-Science Reviews 51, 33-65. Larsen I, MacDonald LH, Brown E, Rough D, Welsh MJ, Pietraszek JH, Libohava Z, Benavides-Solorio JD, Schaffrath K. 2009. Causes of post-fire runoff and erosion: water repellency, cover or soil heating?. Soil Science Society of America Journal 73, 1393-1407. Mataix-Solera J, Guerrero C. 2007. Efecto de los incendios forestales sobre las propiedades edáficas. In: J. Mataix-Solera (Ed.) Incendios Forestales, Suelos y Erosión Hídrica. Caja Mediterráneo CENACAM Font Roja-Alcoi. Alicante. Pp.: 5-40. Mataix-Solera J, Guerrero C, Arcenegui V, Bárcenas G, Zornoza R, Pérez-Bejarano A, Bodí MB, Mataix-Beneyto J, Gómez I, García-Orenes F, Navarro-Pedreño J, Jordán MM, Cerdà A, Doerr SH, Úbeda X, Outeiro L, Jordán A, Zavala LM. 2009. Los incendios forestales y el suelo: un resumen de la investigación realizada por el Grupo de Edafología Ambiental de la UMH en colaboración con otros grupos. In: Cerdà A, Mataix-Solera J. (Eds.). El efecto de los incendios forestales sobre los suelos en España. El estado de la cuestión visto por los científicos españoles. Universitat de Valencia. Valencia. Pp.: 185-218. Mataix-Solera J, Cerdà A, Arcenegui V, Jordán A, Zavala LM. 2011. Fire efects on soil aggregation: a review. Earth-Science Reviews 109, 44-60 Neary DG, Klopatek CC, DeBano LF, Ffolliott PF. 1999. Fire effects on belowground sustainability: a review and synthesis. Forest Ecology and Management 122, 51-71. Pausas JG, Verdú M. 2005. Plant persistence traits in fire-prone ecosystems of the Mediterranean Basin: a phylogenetic approach. Oikos 109, 196-202. Pereira P, Úbeda X, Outeiro L, Martin D. 2009. Factor analysis applied to fire temperature effects on water quality. In: Gómez E, Álvarez K (Eds.), Forest Fires: Detection, Suppression and Prevention. Series Natural Disaster Research, Prediction and Mitigation, Nova Science Publishers, New York, NY. Pp.: 273-285 Pereira P, Cerdà A, Úbeda X, Mataix-Solera J, Martin D, Jordán A, Burguet M. 2013. Spatial models for monitoring the spatio-temporal evolution of ashes after fire - a case study of a burnt grassland in Lithuania. Solid Earth 4, 153-165. Sevink J, Imeson AC, Verstraten JM. 1989. Humus form development and hillslope runoff, and the effects of fire and management, under Mediterranean forest in N.E. Spain. Catena 16, 461-475. Stark NM, 1977. Fire and nutrient cycling in a Douglas-fir/larch forest. Ecology, 58, 16-30. Trabaud L. 2000. Post-fire regeneration of Pinus halepensis forest in the west Mediterranean. In: Ne'eman G, Trabaud L (Eds.), Ecology, biogeography and management of Pinus halepensis and P. brutia forest ecosystems in the Mediterranean basin. Backhuys Publishers. Leiden. Pp.: 257-268. Woods SW, Balfour VN. 2008. Vegetative ash: an important factor in the short term response to rainfall in the post-fire environment. Geophysical Research Abstracts 10, EGU2008-A-00556. Woods SW, Balfour VN. 2010. The effects of soil texture and ash thickness on the post-fire hydrological response from ash-covered soils. Journal of Hydrology 393, 274-286. Zavala LM, Jordán A, Gil J, Bellinfante N, Pain C. 2009. Intact ash and charred litter reduces susceptibility to rain splash erosion post-wildfire Earth Surface Processes and Landforms, 34, 1522-1532. Zavala LM, De Celis R, Jordán A. 2014. How wildfires affect soil properties. A brief review Cuadernos de Investigación Geográfica 40, 311-331. AKNOWLEDGEMENTS This research is part of the POSTFIRE Project (ref. CGL2013-47862-C2-1-R), funded by the Spanish Ministry of Economy and Competitiveness. The authors are also grateful to the Environmental Management Centre (Mykolas Romeris University, Lithuania) and the Michoacan University (Morelia, Mexico) for their support.

  15. Capillary Force between Flexible Filaments.

    PubMed

    Soleimani, Majid; Hill, Reghan J; van de Ven, Theo G M

    2015-08-01

    Liquid droplets bridging filaments are ubiquitous in nature and technology. Although the liquid-surface shape and the capillary force and torque have been studied extensively, the effect of filament flexibility is poorly understood. Here, we show that elastic deformation (at large values of the elasto-capillary number) can significantly affect the liquid-surface shape and capillary force. The equilibrium state of parallel filaments is calculated using analytical approximations and numerical solutions for the fluid interface. The results compare well, and the numerical solution is then applied to crossing filaments. In the investigated range of parameters, the capillary force increases rapidly when the filaments touch. The force decreases continuously when decreasing the liquid volume for parallel hydrophilic filaments but produces a maximum for crossed filaments. The liquid volume at the maximum force is reported when changing the filament flexibility, crossing angle, and contact angle. These results may be beneficial in applications where the strength and structure of wet fibrous materials are important, such as in paper formation and when welding flexible components. PMID:26158380

  16. Capillary electrophoresis for drug analysis

    NASA Astrophysics Data System (ADS)

    Lurie, Ira S.

    1999-02-01

    Capillary electrophoresis (CE) is a high resolution separation technique which is amenable to a wide variety of solutes, including compounds which are thermally degradable, non-volatile and highly polar, and is therefore well suited for drug analysis. Techniques which have been used in our laboratory include electrokinetic chromatography (ECC), free zone electrophoresis (CZE) and capillary electrochromatography (CEC). ECC, which uses a charged run buffer additive which migrates counter to osmotic flow, is excellent for many applications, including, drug screening and analyses of heroin, cocaine and methamphetamine samples. ECC approaches include the use of micelles and charged cyclodextrins, which allow for the separation of complex mixtures. Simultaneous separation of acidic, neutral and basic solutes and the resolution of optical isomers and positional isomers are possible. CZE has been used for the analysis of small ions (cations and anions) in heroin exhibits. For the ECC and CZE experiments performed in our laboratory, uncoated capillaries were used. In contrast, CEC uses capillaries packed with high performance liquid chromatography stationary phases, and offers both high peak capacities and unique selectivities. Applications include the analysis of cannabinoids and drug screening. Although CE suffers from limited concentration sensitivity, it is still applicable to trace analysis of drug samples, especially when using injection techniques such as stacking, or detection schemes such as laser induced fluorescence and extended pathlength UV.

  17. Bacterial motion in narrow capillaries.

    PubMed

    Ping, Liyan; Wasnik, Vaibhav; Emberly, Eldon

    2015-02-01

    Motile bacteria often have to pass through small tortuous pores in soil or tissue of higher organisms. However, their motion in this prevalent type of niche is not fully understood. Here, we modeled it with narrow glass capillaries and identified a critical radius (Rc) for bacterial motion. Near the surface of capillaries narrower than that, the swimming trajectories are helices. In larger capillaries, they swim in distorted circles. Under non-slip condition, the peritrichous Escherichia coli swam in left-handed helices with an Rc of ~10 ?m near glass surface. However, slipping could occur in the fast monotrichous Pseudomonas fluorescens, when a speed threshold was exceeded, and thus both left-handed and right-handed helices were executed in glass capillaries. In the natural non-cylindrical pores, the near-surface trajectories would be spirals and twisted loops. Engaging in such motions reduces the bacterial migration rate. With a given pore size, the run length and the tumbling angle of the bacterium determine the probability and duration of their near-surface motion. Shear flow and chemotaxis potentially enhance it. Based on this observation, the puzzling previous observations on bacterial migration in porous environments can be interpreted. PMID:25764548

  18. Packing columns for capillary electrochromatography.

    PubMed

    Coln, L A; Maloney, T D; Fermier, A M

    2000-07-28

    Considering the current interest in capillary electrochromatography (CEC), performed in packed columns, we present the different methods used to pack capillary columns for use in CEC. General considerations on column packing are given and the column fabrication process is discussed in sufficient detail to allow instruction to those who are not experienced in the field. Five different packing methods are discussed to deliver packing material into the capillary column from a practical view point: slurry pressure packing, packing with supercritical CO2, electrokinetic packing, using centripetal forces, and packing by gravity. Entrapment of particulate material by sintering and sol-gel technology is also mentioned. Although slurry pressure packing procedures are most common, higher separation efficiencies are obtained using other packing approaches. Electrokinetic packing seems to be the simplest technique to deliver the packing material into the capillary columns. Nevertheless, as with the other packing techniques, skill and experience are required to complete all the steps involved in the fabrication of packed columns for CEC. PMID:10961303

  19. Capillary Rise in a Wedge

    ERIC Educational Resources Information Center

    Piva, M.

    2009-01-01

    In introductory-level physics courses, the concept of surface tension is often illustrated using the example of capillary rise in thin tubes. In this paper the author describes experiments conducted using a planar geometry created with two small plates forming a thin wedge. The distribution of the fluid entering the wedge can be studied as a

  20. Capillary Rise in a Wedge

    ERIC Educational Resources Information Center

    Piva, M.

    2009-01-01

    In introductory-level physics courses, the concept of surface tension is often illustrated using the example of capillary rise in thin tubes. In this paper the author describes experiments conducted using a planar geometry created with two small plates forming a thin wedge. The distribution of the fluid entering the wedge can be studied as a…

  1. Bacterial motion in narrow capillaries

    PubMed Central

    Ping, Liyan; Wasnik, Vaibhav; Emberly, Eldon

    2014-01-01

    Motile bacteria often have to pass through small tortuous pores in soil or tissue of higher organisms. However, their motion in this prevalent type of niche is not fully understood. Here, we modeled it with narrow glass capillaries and identified a critical radius (Rc) for bacterial motion. Near the surface of capillaries narrower than that, the swimming trajectories are helices. In larger capillaries, they swim in distorted circles. Under non-slip condition, the peritrichous Escherichia coli swam in left-handed helices with an Rc of ∼10 μm near glass surface. However, slipping could occur in the fast monotrichous Pseudomonas fluorescens, when a speed threshold was exceeded, and thus both left-handed and right-handed helices were executed in glass capillaries. In the natural non-cylindrical pores, the near-surface trajectories would be spirals and twisted loops. Engaging in such motions reduces the bacterial migration rate. With a given pore size, the run length and the tumbling angle of the bacterium determine the probability and duration of their near-surface motion. Shear flow and chemotaxis potentially enhance it. Based on this observation, the puzzling previous observations on bacterial migration in porous environments can be interpreted. PMID:25764548

  2. Motion of an isolated liquid plug inside a capillary tube: effect of contact angle hysteresis

    NASA Astrophysics Data System (ADS)

    Srinivasan, Vyas; Khandekar, Sameer; Bouamrane, Nathan; Lefevre, Frederic; Bonjour, Jocelyn

    2015-01-01

    Dynamics of a single, small and isolated partially wetting liquid plug (of known length L and wettability), placed at rest inside a long, dry, circular capillary tube ( D = 1.5 mm), and subsequently quasi-statically pushed from one end by applying air pressure, the other end being kept exposed to atmosphere, are reported. The air pressure first overcomes the `static' friction manifested by the three-phase contact line at the advancing and receding menisci, and then, the plug motion gets initiated, eventually leading to a terminal velocity (Ca ~ 2.8 × 10-5), when pressure force balances net frictional resistance due to viscous and surface forces. It is seen that, under steady motion, the curvature profiles of the advancing and receding menisci of liquid plug, respectively, remain the same, independent of the plug length. Steady-state pressure drop is dominated by the contribution due to contact angle hysteresis, which is also independent of the plug length. Increasing the system wettability drastically decreased the contact angle hysteresis and the associated net pressure drop.

  3. Gradient elution in capillary electrochromatography

    SciTech Connect

    Anex, D.; Rakestraw, D.J.; Yan, Chao; Dadoo, R.; Zare, R.N.

    1997-08-01

    In analogy to pressure-driven gradient techniques in high-performance liquid chromatography, a system has been developed for delivering electroosmotically-driven solvent gradients for capillary electrochromatography (CEC). Dynamic gradients with sub-mL/min flow rates are generated by merging two electroosmotic flows that are regulated by computer-controlled voltages. These flows are delivered by two fused-silica capillary arms attached to a T-connector, where they mix and then flow into a capillary column that has been electrokinetically packed with 3-mm reversed-phase particles. The inlet of one capillary arm is placed in a solution reservoir containing one mobile phase and the inlet of the other is placed in a second reservoir containing a second mobile phase. Two independent computer-controlled programmable high-voltage power supplies (0-50 kV)--one providing an increasing ramp and the other providing a decreasing ramp--are used to apply variable high-voltage potentials to the mobile phase reservoirs to regulate the electroosmotic flow in each arm. The ratio of the electroosmotic flow rates between the two arms is changed with time according to the computer-controlled voltages to deliver the required gradient profile to the separation column. Experiments were performed to confirm the composition of the mobile phase during a gradient run and to determine the change of the composition in response to the programmed voltage profile. To demonstrate the performance of electroosmotically-driven gradient elution in CEC, a mixture of 16 polycyclic aromatic hydrocarbons (PAHs) was separated in less than 90 minutes. This gradient technique is expected to be well-suited for generating not only solvent gradients in CEC, but also other types of gradients such as pH- and ionic-strength gradients in capillary electrokinetic separations and analyses.

  4. Determination of Labeled Fatty Acids Content in Milk Products, Infant Formula, and Adult/Pediatric Nutritional Formula by Capillary Gas Chromatography: Single-Laboratory Validation, First Action 2012.13.

    PubMed

    Golay, Pierre-Alain; Dong, Yan

    2015-01-01

    The method described is intended for the quantification of all fatty acids, including commercially important groups of fatty acids used for labeling reasons [i. e., trans fatty acids, saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids (PUFA), omega-3, omega-6, and omega-9] and/or individual fatty acids (i. e., linoleic acid, ?-linolenic acid, arachidonic acid, ecosapentaenoic acid, and docosahexaenoic acid) in milk products, infant formula, and adult/pediatric nutritional formula. These products often contain milk fat and/or vegetable oils and are supplemented or not supplemented with oils rich in long-chain PUFA. The determination is performed by direct transesterification of ready-to-feed (RTF) liquid concentrate or powder products without prior fat extraction. Single-laboratory validation (SLV) data were submitted to the AOAC Expert Review Panel (ERP) on Nutrient Methods for review at the AOAC Annual Meeting held on September 30 to October 3, 2012, in Las Vegas, NV. The ERP determined that the data reviewed met the Standard Method Performance Requirements (SMPR 2012.011) set by the AOAC Stakeholder Panel on Infant Formula and Adult Nutritionals (SPIFAN) and was approved as an AOAC Official First Action method. The analytical range for SPIFAN samples was between 0.001 and 7.94 g/100 g reconstituted product or RTF liquid. LOQ was estimated as 0.001 g/100 g, while repeatability and intermediate precision were both less than 1.8% RSD above 0.05 g/100 g and <3.5% RSD at 0.005 g/100 g. Recovery values based on spiking experiments at two different levels of linoleic and linolenic acids ranged from 100.0 to 102.9% for three different SPIFAN products. All the parameters evaluated during the SLV were well within the values defined in SMPR 2012.011. PMID:26651581

  5. On numerical modeling of capillary barriers

    SciTech Connect

    Oldenburg, C.M.; Pruess, K.

    1993-04-01

    Because of their ability to protect underground regions from wetting by downward infiltration, capillary barriers have been objects of considerable interest. A capillary barrier consists of a layer of fine soil overlying a layer of coarse soil. In unsaturated conditions, infiltrating water may be held in the fine medium by capillary force and resist moving into the coarse layer. If the contact is tilted, infiltrating water in the fine layer will build up and flow downdip along the contact, a process known as capillary diversion. Capillary barriers occur naturally or can be created artifically. Recently progress has been made in the theoretical, laboratory, and field study of capillary barriers. Because of the potential significance of capillary barriers on important questions of hazardous waste isolation, and in light of intriguing results of laboratory and field experiments of capillary barriers as well as the simple theoretical results, numerical experiments are presented of an idealized field-scale capillary barrier system with the objective of further understanding the behavior of capillary barriers. An additional objective is the evaluation of the accuracy with which numerical methods can be expected to model the full complement of complicated flow processes associated with the potential high-level nuclear waste repository at Yucca Mountain. To this end, different mobility weighting schemes and grid orientation effects in the flow in the model capillary barrier system are investigated.

  6. Controlled wettability based on reversible micro-cracking on a shape memory polymer surface.

    PubMed

    Han, Yu; Liu, Yuxuan; Wang, Wenxin; Leng, Jinsong; Jin, Peng

    2016-03-14

    Wettability modification on a polymer surface is of immense importance for flexible electronics and biomedical applications. Herein, controlled wettability of a styrene-based shape memory polymer has been realized by introducing micro-cracks on the polymer surface for the first time. The cracks were purposely prepared by thin metal film constrained deformation on the polymer. After the removal of the metallic film, wettability was dramatically enhanced by showing a remarkable reduction in the contact angle with water droplets from 85° to 25°. Subsequent systematic characterization techniques like XPS and SEM revealed that such observation could be attributed to the increased density of hydrophilic groups and the roughened surface. In addition, by controlling the temperature for annealing the treated polymer, the surface could be switched reversely to water-repellent. Therefore, this paper offers a smart tactic to manipulate the surface wettability of a shape memory polymer freely. The features of the controlled wettability surface such as high tenability, high stability and easy fabrication are promising for microfluidic switching and molecule/cell capture-release. PMID:26865175

  7. Mechanistic study of wettability alteration of oil-wet sandstone surface using different surfactants

    NASA Astrophysics Data System (ADS)

    Hou, Bao-feng; Wang, Ye-fei; Huang, Yong

    2015-03-01

    Different analytical methods including Fourier transform infrared (FTIR), atomic force microscopy (AFM), zeta potential measurements, contact angle measurements and spontaneous imbibition tests were utilized to make clear the mechanism for wettability alteration of oil-wet sandstone surface using different surfactants. Results show that among three types of surfactants including cationic surfactants, anionic surfactants and nonionic surfactants, the cationic surfactant CTAB demonstrates the best effect on the wettability alteration of oil-wet sandstone surface. The positively charged head groups of CTAB molecules and carboxylic acid groups from crude oil could interact to form ion pairs, which could be desorbed from the solid surface and solubilized into the micelle formed by CTAB. Thus, the water-wetness of the solid surface is improved. Nonionic surfactant TX-100 could be adsorbed on oil-wet sandstone surface through hydrogen bonds and hydrophobic interaction to alter the wettability of oil-wet solid surface. The wettability alteration of oil-wet sandstone surface using the anionic surfactant POE(1) is caused by hydrophobic interaction. Due to the electrostatic repulsion between the anionic surfactant and the negatively charged surface, POE(1) shows less effect on the wettability alteration of oil-wet sandstone surface.

  8. Time dependent wettability of graphite upon ambient exposure: The role of water adsorption

    NASA Astrophysics Data System (ADS)

    Amadei, Carlo A.; Lai, Chia-Yun; Heskes, Daan; Chiesa, Matteo

    2014-08-01

    We report the temporal evolution of the wettability of highly ordered pyrolytic graphite (HOPG) exposed to environmental conditions. Macroscopic wettability is investigated by static and dynamic contact angles (SCA and DCA) obtaining values comparable to the ones presented in the literature. SCA increases from 68 to 90 during the first hour of exposure after cleaving, whereas DCA is characterized by longer-scale (24 h) time evolution. We interpret these results in light of Fourier transform infrared spectroscopy, which indicates that the evolution of the HOPG wettability is due to adsorption of molecules from the surrounding atmosphere. This hypothesis is further confirmed by nanoscopic observations obtained by atomic force microscope (AFM)-based force spectroscopy, which monitor the evolution of surface properties with a spatial resolution superior to macroscopic experiments. Moreover, we observe that the results of macro- and nanoscale measurements evolve in similar fashion with time and we propose a quantitative correlation between SCA and AFM measurements. Our results suggest that the cause of the transition in the wettability of HOPG is due to the adsorption of hydrocarbon contaminations and water molecules from the environment. This is corroborated by annealing the HOPG is vacuum conditions at 150, allowing the desorption of molecules on the surface, and thus re-establishing the initial macro and nano surface properties. Our findings can be used in the interpretation of the wettability of more complicated systems derived from HOPG (i.e., graphene).

  9. Time dependent wettability of graphite upon ambient exposure: The role of water adsorption

    SciTech Connect

    Amadei, Carlo A.; Lai, Chia-Yun; Heskes, Daan; Chiesa, Matteo

    2014-08-28

    We report the temporal evolution of the wettability of highly ordered pyrolytic graphite (HOPG) exposed to environmental conditions. Macroscopic wettability is investigated by static and dynamic contact angles (SCA and DCA) obtaining values comparable to the ones presented in the literature. SCA increases from ∼68° to ∼90° during the first hour of exposure after cleaving, whereas DCA is characterized by longer-scale (24 h) time evolution. We interpret these results in light of Fourier transform infrared spectroscopy, which indicates that the evolution of the HOPG wettability is due to adsorption of molecules from the surrounding atmosphere. This hypothesis is further confirmed by nanoscopic observations obtained by atomic force microscope (AFM)-based force spectroscopy, which monitor the evolution of surface properties with a spatial resolution superior to macroscopic experiments. Moreover, we observe that the results of macro- and nanoscale measurements evolve in similar fashion with time and we propose a quantitative correlation between SCA and AFM measurements. Our results suggest that the cause of the transition in the wettability of HOPG is due to the adsorption of hydrocarbon contaminations and water molecules from the environment. This is corroborated by annealing the HOPG is vacuum conditions at 150°, allowing the desorption of molecules on the surface, and thus re-establishing the initial macro and nano surface properties. Our findings can be used in the interpretation of the wettability of more complicated systems derived from HOPG (i.e., graphene)

  10. Effects of initial surface wettability on biofilm formation and subsequent settlement of Hydroides elegans.

    PubMed

    Huggett, Megan J; Nedved, Brian T; Hadfield, Michael G

    2009-01-01

    Hydroides elegans is a major fouling organism in tropical waters around the world, including Pearl Harbor, Hawaii. To determine the importance of initial surface characteristics on biofilm community composition and subsequent colonization by larvae of H. elegans, the settlement and recruitment of larvae to biofilmed surfaces with six different initial surface wettabilities were tested in Pearl Harbor. Biofilm community composition, as determined by a combined approach of denaturing gradient gel electrophoresis and fluorescence in situ hybridization, was similar across all surfaces, regardless of initial wettability, and all surfaces had distinct temporal shifts in community structure over a 10 day period. Larvae settled and recruited in higher numbers to surfaces with medium to low wettability in both May and August, and also to slides with high wettability in August. Pearl Harbor biofilm communities developed similarly on a range of surface wettabilities, and after 10 days in Pearl Harbor all surfaces were equally attractive to larvae of Hydroides elegans, regardless of initial surface properties. PMID:19306143

  11. Dropwise Evaporative Cooling of Heated Surfaces with Various Wettability Characteristics Obtained by Nanostructure Modifications.

    PubMed

    Chen, Jian-Nan; Zhang, Zhen; Ouyang, Xiao-Long; Jiang, Pei-Xue

    2016-12-01

    A numerical and experimental investigation was conducted to analyze dropwise evaporative cooling of heated surfaces with various wettability characteristics. The surface wettability was tuned by nanostructure modifications. Spray-cooling experiments on these surfaces show that surfaces with better wettability have better heat transfer rate and higher critical heat flux (CHF). Single droplet impingement evaporative cooling of a heated surface was then investigated numerically with various wettability conditions to characterize the effect of contact angle on spray-cooling heat transfer. The volume of fluid (VOF) model with variable-time stepping was used to capture the time-dependent liquid-gas interface motion throughout the computational domain with the kinetic theory model used to predict the evaporation rate at the liquid-gas interface. The numerical results agree with the spray-cooling experiments that dropwise evaporative cooling is much better on surfaces with better wettability because of the better liquid spreading and convection, better liquid-solid contact, and stronger liquid evaporation. PMID:27003427

  12. Capillary electrophoresis systems and methods

    DOEpatents

    Dorairaj, Rathissh (Hillsboro, OR); Keynton, Robert S. (Louisville, KY); Roussel, Thomas J. (Louisville, KY); Crain, Mark M. (Georgetown, IN); Jackson, Douglas J. (New Albany, IN); Walsh, Kevin M. (Louisville, KY); Naber, John F. (Goshen, KY); Baldwin, Richard P. (Louisville, KY); Franco, Danielle B. (Mount Washington, KY)

    2011-08-02

    An embodiment of the invention is directed to a capillary electrophoresis apparatus comprising a plurality of separation micro-channels. A sample loading channel communicates with each of the plurality of separation channels. A driver circuit comprising a plurality of electrodes is configured to induce an electric field across each of the plurality of separation channels sufficient to cause analytes in the samples to migrate along each of the channels. The system further comprises a plurality of detectors configured to detect the analytes.

  13. Microfluidic design rules for capillary slot-based electrospray sources

    NASA Astrophysics Data System (ADS)

    Brinkmann, M.; Blossey, R.; Arscott, S.; Druon, C.; Tabourier, P.; Le Gac, S.; Rolando, C.

    2004-09-01

    We formulate microfluidic design principles for electrospray ionization sources based on a rectangular capillary slot formed by two triangular cantilevers. Spontaneous imbibition of the test liquids into the slot by capillary action provides a robust mechanism for liquid transport from a reservoir to the cantilever tip where an electrospray is generated upon application of a voltage. The correct functioning of the source requires the liquid bridging the slot to have a negative Laplace pressure. Imbibition is controlled by the ratio of slot width to height w /h and the intrinsic contact angles ?w, ?s of the liquid with the slot walls and the cantilever faces, respectively. Based on these parameters we derive a simple criterion for the complete filling of the slot.

  14. Development of a Contingency Capillary Wastewater Management Device

    NASA Technical Reports Server (NTRS)

    Thomas, Evan A.

    2010-01-01

    The Personal Body .Attached Liquid Liquidator (PBALL) is conceived as a passive, capillary driven contingency wastewater disposal device. In this contingency scenario, the airflow system on the NASA Crew Exploration Vehicle (CEV) is assumed to have failed, leaving only passive hardware and vacuum vent to dispose of the wastewater. To meet these needs, the PBALL was conceived to rely on capillary action and urine wetting design considerations. The PBALL is designed to accommodate a range of wetting conditions, from 0deg < (theta)adv approx. 90deg, be adaptable for both male and female use, collect and retain up to a liter of urine, minimize splash-back, and allow continuous drain of the wastewater to vacuum while minimizing cabin air loss. A sub-scale PBALL test article was demonstrated on NASA's reduced gravity aircraft in April, 2010.

  15. Force Measurements Using Capillary Instabilities

    NASA Astrophysics Data System (ADS)

    Steiner, Ullrich

    2005-03-01

    Planar surfaces are stabilized by the Laplace pressure, which dampens the entire capillary wave spectrum of a liquid surface. Pattern formation at surfaces and in thin films are therefore the consequence of a destabilizing pressure. The analysis of pattern formation processes can therefore be used to quantitatively measure the destabilizing force. My presentation will focus on three examples for such force measurements: *Electrohydrodynamic Instabilities. It is long known that electric fields destabilize liquid surfaces. An electric field applied across at thin polymer film causes the amplification of a single capillary mode, which is quantitatively predicted by a linear stability analysis. The good quantitative agreement of experimental results and theoretical predictions illustrates the usefulness of our approach. *Acoustic Casimir Effect. We show that the confinement of thermal modes (acoustic phonons) in thin films lead toe a Casimir-type force that leads to the breakup of thin polymer films. *Film Instabilities caused by temperature gradients. A high temperature gradient across a thin polymer film causes a amplified capillary instability. This non-convective effect is driven by the diffusion of heat across a polymer-air double layer and is a function of the acoustic impedance of the polymer-air interface.

  16. Treelike networks accelerating capillary flow

    NASA Astrophysics Data System (ADS)

    Shou, Dahua; Ye, Lin; Fan, Jintu

    2014-05-01

    Transport in treelike networks has received wide attention in natural systems, oil recovery, microelectronic cooling systems, and textiles. Existing studies are focused on transport behaviors under a constant potential difference (including pressure, temperature, and voltage) in a steady state [B. Yu and B. Li, Phys. Rev. E 73, 066302 (2006), 10.1103/PhysRevE.73.066302; J. Chen, B. Yu, P. Xu, and Y. Li, Phys. Rev. E 75, 056301 (2007), 10.1103/PhysRevE.75.056301]. However, dynamic (time-dependent) transport in such systems has rarely been concerned. In this work, we theoretically investigate the dynamics of capillary flow in treelike networks and design the distribution of radius and length of local branches for the fastest capillary flow. It is demonstrated that capillary flow in the optimized tree networks is faster than in traditional parallel tube nets under fixed constraints. As well, the flow time of the liquid is found to increase approximately linearly with penetration distance, which differs from Washburn's classic description that flow time increases as the square of penetration distance in a uniform tube.

  17. Treelike networks accelerating capillary flow.

    PubMed

    Shou, Dahua; Ye, Lin; Fan, Jintu

    2014-05-01

    Transport in treelike networks has received wide attention in natural systems, oil recovery, microelectronic cooling systems, and textiles. Existing studies are focused on transport behaviors under a constant potential difference (including pressure, temperature, and voltage) in a steady state [B. Yu and B. Li, Phys. Rev. E 73, 066302 (2006); J. Chen, B. Yu, P. Xu, and Y. Li, Phys. Rev. E 75, 056301 (2007)]. However, dynamic (time-dependent) transport in such systems has rarely been concerned. In this work, we theoretically investigate the dynamics of capillary flow in treelike networks and design the distribution of radius and length of local branches for the fastest capillary flow. It is demonstrated that capillary flow in the optimized tree networks is faster than in traditional parallel tube nets under fixed constraints. As well, the flow time of the liquid is found to increase approximately linearly with penetration distance, which differs from Washburn's classic description that flow time increases as the square of penetration distance in a uniform tube. PMID:25353880

  18. Manipulating surface wettability and oil absorbency of diatomite depending on processing and ambient conditions

    NASA Astrophysics Data System (ADS)

    Özen, İlhan; Şimşek, Süleyman; Okyay, Gamze

    2015-03-01

    In this study, a diatomite sample, which is a natural inorganic mineral with inherently high water and oil absorption capacity, was subjected to grinding before surface modification. Afterwards, the diatomite surface was modified via facile methods using a fluorocarbon (FC) chemical and stearic acid (SA) in addition to the sol-gel fluorosilanization (FS) process. The water and oil wettability, and oil absorbency properties of the unmodified and modified diatomites were investigated in addition to diatomite characterizations such as chemical content, surface area, particle size distribution, morphology, and modification efficiency. It was revealed that the wettability was changed completely depending on the surface modification agent and the media used, while the oil absorbency property surprisingly did not change. On the other hand, the oil absorbency was worsened by the grinding process, whereas the wettability was not affected.

  19. Radial Wettable Gradient of Hot Surface to Control Droplets Movement in Directions

    PubMed Central

    Feng, Shile; Wang, Sijie; Tao, Yuanhao; Shang, Weifeng; Deng, Siyan; Zheng, Yongmei; Hou, Yongping

    2015-01-01

    A radial wettable gradient was fabricated on the surface of graphite plate by a simple one-step anodic oxidation process. It was found that the direction and value of the wettable gradient could be easily controlled by adjusting current and oxidation time gradient. With the increase of surface temperature, droplets on surface not only exhibited the transition of boiling mode, but also showed the controlled radial spreading, evaporation and movement behaviors. These phenomena could be attributed to the cooperation of wettability force, hysteresis force and vapor pressure (Leidenfrost effect). Especially, the controlled radial convergence or divergence of droplets with high velocity were realized on the surfaces with either inside or outside radial gradient, which would have crucial applications in the design of microfluidic devices and the exploration of the biotechnology. PMID:25975722

  20. Wettability study of modified silicon dioxide surface using environmental scanning electron microscopy

    SciTech Connect

    Aronov, Daniel; Rosenman, Gil; Barkay, Zahava

    2007-04-15

    The wettability analysis is often used to characterize a surface in micro and nanometer scale. At these small scales, effects of the contact line tension are also expected to play a significant role. Wettability effect is studied using environmental scanning electron microscopy on silicon dioxide surface modified by a low-energy electron irradiation method. Electron-induced wettability variation and patterning at micrometer scale on silicon dioxide substrate allow investigating the contact angle dependence on the water droplet line curvature and calculating values of the line tension of a three-phase system (solid-liquid-vapor) of about 10{sup -9} J/m that is consistent with theoretical estimations. It is found that the sign of the line tension alters from positive for hydrophilic surface to negative for hydrophobic one.

  1. Radial Wettable Gradient of Hot Surface to Control Droplets Movement in Directions

    NASA Astrophysics Data System (ADS)

    Feng, Shile; Wang, Sijie; Tao, Yuanhao; Shang, Weifeng; Deng, Siyan; Zheng, Yongmei; Hou, Yongping

    2015-05-01

    A radial wettable gradient was fabricated on the surface of graphite plate by a simple one-step anodic oxidation process. It was found that the direction and value of the wettable gradient could be easily controlled by adjusting current and oxidation time gradient. With the increase of surface temperature, droplets on surface not only exhibited the transition of boiling mode, but also showed the controlled radial spreading, evaporation and movement behaviors. These phenomena could be attributed to the cooperation of wettability force, hysteresis force and vapor pressure (Leidenfrost effect). Especially, the controlled radial convergence or divergence of droplets with high velocity were realized on the surfaces with either inside or outside radial gradient, which would have crucial applications in the design of microfluidic devices and the exploration of the biotechnology.

  2. Fabrication of a wettability-gradient surface on copper by screen-printing techniques

    NASA Astrophysics Data System (ADS)

    Huang, Ding-Jun; Leu, Tzong-Shyng

    2015-08-01

    In this study, a screen-printing technique is utilized to fabricate a wettability-gradient surface on a copper substrate. The pattern definitions on the copper surface were freely fabricated to define the regions with different wettabilities, for which the printing definition technique was developed as an alternative to the existing costly photolithography techniques. This fabrication process using screen printing in tandem with chemical modification methods can easily realize an excellent wettability-gradient surface with superhydrophobicity and superhydrophilicity. Surface analyses were performed to characterize conditions in some fabrication steps. A water droplet movement sequence is provided to clearly demonstrate the droplet-driving effectiveness of the fabricated gradient surface. The droplet-driving efficiency offers a promising solution for condensation heat transfer applications in the foreseeable future.

  3. Influence of surface contamination on the wettability of heat transfer surfaces

    DOE PAGESBeta

    Forrest, Eric Christopher; Schulze, Roland; Liu, Cheng; Dombrowski, David

    2015-08-08

    In this study, the wettability of heat transfer surfaces plays an important role in liquid–vapor phase change phenomena, including boiling incipience, the critical heat flux, the Leidenfrost transition, and condensation. The influence of adsorbed surface contamination at the nanoscale, though seldom considered, can have a profound impact on wetting behavior. This study quantitatively investigates the impact of contaminant layer thickness on wettability. Various cleaning treatments are explored on zirconium and 6061 aluminum to determine the effect on contaminant and oxide layer thickness. Angle-resolved X-ray photoelectron spectroscopy can be used to measure the thickness of oxide and contaminant layers, which ismore » then correlated to wettability by measuring the equilibrium contact angle. Results indicate that even after solvent cleaning, the contact angle of water on practical heat transfer surfaces is dominated by a hydrocarbon contaminant overlayer around five nanometers thick.« less

  4. Influence of surface contamination on the wettability of heat transfer surfaces

    SciTech Connect

    Forrest, Eric Christopher; Schulze, Roland; Liu, Cheng; Dombrowski, David

    2015-08-08

    In this study, the wettability of heat transfer surfaces plays an important role in liquid–vapor phase change phenomena, including boiling incipience, the critical heat flux, the Leidenfrost transition, and condensation. The influence of adsorbed surface contamination at the nanoscale, though seldom considered, can have a profound impact on wetting behavior. This study quantitatively investigates the impact of contaminant layer thickness on wettability. Various cleaning treatments are explored on zirconium and 6061 aluminum to determine the effect on contaminant and oxide layer thickness. Angle-resolved X-ray photoelectron spectroscopy can be used to measure the thickness of oxide and contaminant layers, which is then correlated to wettability by measuring the equilibrium contact angle. Results indicate that even after solvent cleaning, the contact angle of water on practical heat transfer surfaces is dominated by a hydrocarbon contaminant overlayer around five nanometers thick.

  5. Radial wettable gradient of hot surface to control droplets movement in directions.

    PubMed

    Feng, Shile; Wang, Sijie; Tao, Yuanhao; Shang, Weifeng; Deng, Siyan; Zheng, Yongmei; Hou, Yongping

    2015-01-01

    A radial wettable gradient was fabricated on the surface of graphite plate by a simple one-step anodic oxidation process. It was found that the direction and value of the wettable gradient could be easily controlled by adjusting current and oxidation time gradient. With the increase of surface temperature, droplets on surface not only exhibited the transition of boiling mode, but also showed the controlled radial spreading, evaporation and movement behaviors. These phenomena could be attributed to the cooperation of wettability force, hysteresis force and vapor pressure (Leidenfrost effect). Especially, the controlled radial convergence or divergence of droplets with high velocity were realized on the surfaces with either inside or outside radial gradient, which would have crucial applications in the design of microfluidic devices and the exploration of the biotechnology. PMID:25975722

  6. Surface free energy predominates in cell adhesion to hydroxyapatite through wettability.

    PubMed

    Nakamura, Miho; Hori, Naoko; Ando, Hiroshi; Namba, Saki; Toyama, Takeshi; Nishimiya, Nobuyuki; Yamashita, Kimihiro

    2016-05-01

    The initial adhesion of cells to biomaterials is critical in the regulation of subsequent cell behaviors. The purpose of this study was to investigate a mechanism through which the surface wettability of biomaterials can be improved and determine the effects of biomaterial surface characteristics on cellular behaviors. We investigated the surface characteristics of various types of hydroxyapatite after sintering in different atmospheres and examined the effects of various surface characteristics on cell adhesion to study cell-biomaterial interactions. Sintering atmosphere affects the polarization capacity of hydroxyapatite by changing hydroxide ion content and grain size. Compared with hydroxyapatite sintered in air, hydroxyapatite sintered in saturated water vapor had a higher polarization capacity that increased surface free energy and improved wettability, which in turn accelerated cell adhesion. We determined the optimal conditions of hydroxyapatite polarization for the improvement of surface wettability and acceleration of cell adhesion. PMID:26952425

  7. WETTABILITY AND PREDICTION OF OIL RECOVERY FROM RESERVOIRS DEVELOPED WITH MODERN DRILLING AND COMPLETION FLUIDS

    SciTech Connect

    Jill S. Buckley; Norman R. Morrow

    2003-05-01

    This report summarizes the experimental results of some baseline imbibition tests on recovery of mineral oil at very strongly water wet conditions (VSWW) from sandstones with air permeability ranging from 80 to 360 md. Mixed wettability cores were prepared by adsorption from either Minnelusa or Gullfaks crude oil using either synthetic Minnelusa reservoir brine or sea water. Recovery of two synthetic-based mud (SBM) base oils, Petrofree(reg sign)SF and LVT 200 from mixed wettability cores gave results that correlated closely with results for refined oils with viscosities ranging from 3.8 to 84 cp. Two synthetic-based mud emulsifiers (LE SUPERMUL and EZ MUL(reg sign)NT) were added to mineral oil and tested for their effect on the wettability of MXW-F core samples as indicated by spontaneous imbibition. In both cases a significant decrease in water wetness was obtained.

  8. Fluid Delivery System For Capillary Electrophoretic Applications.

    DOEpatents

    Li, Qingbo (State College, PA); Liu, Changsheng (State College, PA); Kane, Thomas E. (State College, PA); Kernan, John R. (Loganton, PA); Sonnenschein, Bernard (Brooklyn, NY); Sharer, Michael V. (Tyrone, PA)

    2002-04-23

    An automated electrophoretic system is disclosed. The system employs a capillary cartridge having a plurality of capillary tubes. The cartridge has a first array of capillary ends projecting from one side of a plate. The first array of capillary ends are spaced apart in substantially the same manner as the wells of a microtitre tray of standard size. This allows one to simultaneously perform capillary electrophoresis on samples present in each of the wells of the tray. The system includes a stacked, dual carrousel arrangement to eliminate cross-contamination resulting from reuse of the same buffer tray on consecutive executions from electrophoresis. The system also has a gel delivery module containing a gel syringe/a stepper motor or a high pressure chamber with a pump to quickly and uniformly deliver gel through the capillary tubes. The system further includes a multi-wavelength beam generator to generate a laser beam which produces a beam with a wide range of wavelengths. An off-line capillary reconditioner thoroughly cleans a capillary cartridge to enable simultaneous execution of electrophoresis with another capillary cartridge. The streamlined nature of the off-line capillary reconditioner offers the advantage of increased system throughput with a minimal increase in system cost.

  9. Time Evolution of the Wettability of Supported Graphene under Ambient Air Exposure

    PubMed Central

    2016-01-01

    The wettability of graphene is both fundamental and crucial for interfacing in most applications, but a detailed understanding of its time evolution remains elusive. Here we systematically investigate the wettability of metal-supported, chemical vapor deposited graphene films as a function of ambient air exposure time using water and various other test liquids with widely different surface tensions. The wettability of graphene is not constant, but varies with substrate interactions and air exposure time. The substrate interactions affect the initial graphene wettability, where, for instance, water contact angles of ∼85 and ∼61° were measured for Ni and Cu supported graphene, respectively, after just minutes of air exposure. Analysis of the surface free energy components indicates that the substrate interactions strongly influence the Lewis acid–base component of supported graphene, which is considerably weaker for Ni supported graphene than for Cu supported graphene, suggesting that the classical van der Waals interaction theory alone is insufficient to describe the wettability of graphene. For prolonged air exposure, the effect of physisorption of airborne contaminants becomes increasingly dominant, resulting in an increase of water contact angle that follows a universal linear-logarithmic relationship with exposure time, until saturating at a maximum value of 92–98°. The adsorbed contaminants render all supported graphene samples increasingly nonpolar, although their total surface free energy decreases only by 10–16% to about 37–41 mJ/m2. Our finding shows that failure to account for the air exposure time may lead to widely different wettability values and contradicting arguments about the wetting transparency of graphene. PMID:26900413

  10. Influence of biochar and terra preta substrates on wettability and erodibility of soils

    NASA Astrophysics Data System (ADS)

    Smetanova, A.; Dotterweich, M.; Diehl, D.; Ulrich, U.; Fohrer, N.

    2012-04-01

    Biochar (BC) and terra preta substrates (TPS) have recently been promoted as soil amendments suitable for soil stabilization, soil amelioration and long-term carbon sequestration. BC is a carbon-enriched substance produced by thermal decomposition of organic material. TPS is composed of liquid and solid organic matter, including BC, altered by acid-lactic fermentation. Their effect on wettability, soil erodibility and nutrient discharge through overland flow was studied by laboratory experiments. At water contents between 0 and 100% BC is water repellent, while TPS changes from a wettable into a repellent state. The 5 and 10 vol % mixtures of BC and 10 and 20 vol% mixtures of TPS with sand remain mainly wettable during drying but repellency maxima are shifted to higher water contents with respect to pure sand and are mainly of subcritical nature. The runoff response was dominated by infiltration properties of the substrates rather than their wettability.Only one mixtures (20% TPS) produced more runoff than sandy-loamy soil on a 15% slope at an intensity of 25 mmh-1. The 10% BC decreased runoff by up to 40%. At higher rainfall intensities (45 and 55 mmh-1) the 10% TPS7 was up to 35% less erodible than 10% BC. Despite the TPS containing more nutrients, nutrient discharge varied between types of nutrients, slopes, rainfall intensities and mixtures. The application of a 1 cm layer onto the soil surface instead of 10% mixtures is not recommended due to high nutrient concentrations in the runoff and the wettability of pure substrates. The usage of 10% BC in lowland areas with low frequency and low-intensity precipitation and 10% TPS7 in areas with higher rainfall intensities appears to be appropriate and commendable according to current results. However, together with reversibility of repellency, it needs to undergo further examination in the field under different environmental and land use conditions Key words: biochar, terra preta substrate, wettability, erodibility, nutrient discharge

  11. Altering Reservoir Wettability to Improve Production from Single Wells

    SciTech Connect

    W. W. Weiss

    2006-09-30

    Many carbonate reservoirs are naturally fractured and typically produce less than 10% original oil in place during primary recovery. Spontaneous imbibition has proven an important mechanism for oil recovery from fractured reservoirs, which are usually weak waterflood candidates. In some situations, chemical stimulation can promote imbibition of water to alter the reservoir wettability toward water-wetness such that oil is produced at an economic rate from the rock matrix into fractures. In this project, cores and fluids from five reservoirs were used in laboratory tests: the San Andres formation (Fuhrman Masho and Eagle Creek fields) in the Permian Basin of Texas and New Mexico; and the Interlake, Stony Mountain, and Red River formations from the Cedar Creek Anticline in Montana and South Dakota. Solutions of nonionic, anionic, and amphoteric surfactants with formation water were used to promote waterwetness. Some Fuhrman Masho cores soaked in surfactant solution had improved oil recovery up to 38%. Most Eagle Creek cores did not respond to any of the tested surfactants. Some Cedar Creek anticline cores had good response to two anionic surfactants (CD 128 and A246L). The results indicate that cores with higher permeability responded better to the surfactants. The increased recovery is mainly ascribed to increased water-wetness. It is suspected that rock mineralogy is also an important factor. The laboratory work generated three field tests of the surfactant soak process in the West Fuhrman Masho San Andres Unit. The flawlessly designed tests included mechanical well clean out, installation of new pumps, and daily well tests before and after the treatments. Treatments were designed using artificial intelligence (AI) correlations developed from 23 previous surfactant soak treatments. The treatments were conducted during the last quarter of 2006. One of the wells produced a marginal volume of incremental oil through October. It is interesting to note that the field tests were conducted in an area of the field that has not met production expectations. The dataset on the 23 Phosphoria well surfactant soaks was updated. An analysis of the oil decline curves indicted that 4.5 lb of chemical produced a barrel of incremental oil. The AI analysis supports the adage 'good wells are the best candidates.' The generally better performance of surfactant in the high permeability core laboratory tests supports this observation. AI correlations were developed to predict the response to water-frac stimulations in a tight San Andres reservoir. The correlations maybe useful in the design of Cedar Creek Anticline surfactant soak treatments planned for next year. Nuclear Magnetic Resonance scans of dolomite cores to measure porosity and saturation during the high temperature laboratory work were acquired. The scans could not be correlated with physical measurement using either conventional or AI methods.

  12. New concept for coal wettability evaluation and modulation. Technical progress report, April 1, 1994--June 30, 1994

    SciTech Connect

    Hu, W.

    1994-08-01

    This project is concerned with the new concept for coal surface wettability and floatability and modulation. The objective of this work is to study the fundamental surface chemistry features about the evaluation of the surface wettability and floatability of coal and pyrite, and establish a new separation strategy which could contribute to advanced coal-cleaning for premium fuel applications.

  13. Brain capillaries in Alzheimer's disease.

    PubMed

    Baloyannis, Stavros J

    2015-01-01

    Alzheimer's disease is the most common cause of irreversible dementia, affecting mostly the presenile and senile age, shaping a tragic profile in the epilogue of the life of the suffering people. Due to the severity and the social impact of the disease an ongoing research activity is in climax nowadays, associated with many legal, social, ethical, humanitarian, philosophical and economic considerations. From the neuropathological point of view the disease is characterized by dendritic pathology, loss of synapses and dendritic spines, affecting mostly selective neuronal networks of critical importance for memory and cognition, such as the basal forebrain cholinergic system, the medial temporal regions, the hippocampus and many neocortical association areas. Tau pathology consisted of intracellular accumulation of neurofibrillary tangles of hyperphosphorilated tau protein and accumulation of Aβ-peptide's deposits, defined as neuritic plaques, are the principal neuropathological diagnostic criteria of the disease. The neurotoxic properties of the oligomerics of the Aβ-peptide and tau mediated neurodegeneration are among the main causative factors of impaired synaptic plasticity, neuronal loss, dendritic alterations and tremendous synaptic loss. The gradual degeneration of the organelles, particularly mitochondria, smooth endoplasmic reticulum and Golgi apparatus, visualized clearly by electron microscopy (EM), emphasize the importance of the oxidative stress and amyloid toxicity in the pathogenetic cascade of the disease. The vascular factor may be an important component of the whole spectrum of the pathogenesis of AD. It is of substantial importance the concept that the structural alterations of the brain capillaries, may contribute in the pathology of AD, given that the disruption of the BBB may induce exacerbation of AD pathology, by promoting inflammation around the blood capillaries and in the neuropile space diffusely. From the morphological point of view, silver impregnation techniques revealed a marked tortuosity of the capillaries in early cases of AD. In addition, the distance between two branch points is longer in capillaries of AD brains, whereas the branch point density as well as the ratio of the branch point density to astrocytic density is substantially decreased in AD in comparison with age matched normal controls. EM revealed, that the most frequent morphological alterations of the brain capillaries in AD consist of thickness, splitting and duplication of the basement membrane, reduction of the length of tight junctions, decrease of the number of tight junctions per vessel length, associated as a rule, with morphological alterations of the mitochondria of the endothelial cells, the pericytes and the perivascular astrocytic processes. The number of the pinocytotic vesicles is substantially increase in the endothelium of the brain capillaries in AD in comparison with age matched normal controls. Endothelial cells play a very important role in the transport systems in the brain. Subsequently, the dysfunction of the endothelial cells and the disruption of the BBB may induce serious impairment in the transport system. The dysfunction of the brain capillaries may result in releasing neurotoxic factors, such as thrombin, pro-inflammatory cytokines, nitric oxide and leukocyte adhesion molecules, and in abnormal regulation of Aβ-peptide homeostasis in the brain. The impairment of the brain capillaries in structures of the brain, which are crucial for the homeostatic equilibrium, such as the hypothalamic nuclei, may induce autonomic dysfunction, which usually occur in the advanced stages of AD, affecting dramatically the viability of the patients. Degeneration of the pericytes is also observed emphasizing even more the importance of the vascular factor in AD. Pericytes may serve as integrators, coordinators and effectors of blood-brain barrier structure and maintenance, and play a key role in microvascular stability, capillary density and angiogenesis. The correlation between AD pathology and vascular pathology, at the level of brain capillaries and BBB, raises the rational question, whether the efficient treatment of the vascular factor might be beneficial for the patients who suffer from AD. It is reasonable that any protection of the brain capillaries at the initial stages of the disease might contribute in the abbreviation of the long chain of pathological alteration, which occur following the disruption of the BBB, which serves as the essential interface between the vascular system and the brain. PMID:26665235

  14. Surface treatment of polymer microfibrillar structures for improved surface wettability and adhesion

    NASA Astrophysics Data System (ADS)

    Peyvandi, Amirpasha; Abideen, Saqib Ul; Huang, Yue; Lee, Ilsoon; Soroushian, Parviz; Lu, Jue

    2014-01-01

    The effects of altering the polymer surface characteristics on adhesion qualities of bio-inspired fibrillar adhesives were found to be significant. Treatment of fibril tip surfaces in polymer fibrillar adhesives improved their wettability and adhesion capacity. Surface modifications of fibril tips involved UV/Ozone and oxygen plasma treatments for making the fibril tips more hydrophilic. These surface treatment effects, however, tend to degrade over time (rendering hydrophobic recovery). The stability of treated (hydrophilic) surfaces was improved, while retaining their wettability, through coating with a polyelectrolyte such as polyethyleneimine (PEI) via self-assembly.

  15. CO2 -Responsive Nanofibrous Membranes with Switchable Oil/Water Wettability.

    PubMed

    Che, Hailong; Huo, Meng; Peng, Liao; Fang, Tommy; Liu, Na; Feng, Lin; Wei, Yen; Yuan, Jinying

    2015-07-27

    Responsive polymer interfacial materials are ideal candidates for controlling surface wetting behavior. Here we developed smart nanostructured electrospun polymer membranes which are capable of switching oil/water wettability using CO2 as the trigger. In particular, the combination of CO2 -responsiveness and porous nanostructure enables the as-prepared membranes to be used as a novel oil/water on-off switch. We anticipate that the promising versatility and simplicity of this system would not only open up a new way of surface wettability change regulation by gas, but also have obvious advantages in terms of highly controlled oil/water separation and CO2 applications. PMID:26079643

  16. WETTABILITY AND PREDICTION OF OIL RECOVERY FROM RESERVOIRS DEVELOPED WITH MODERN DRILLING AND COMPLETION FLUIDS

    SciTech Connect

    Jill S. Buckley; Norman R. Morrow

    2006-01-01

    The objectives of this project are: (1) to improve understanding of the wettability alteration of mixed-wet rocks that results from contact with the components of synthetic oil-based drilling and completion fluids formulated to meet the needs of arctic drilling; (2) to investigate cleaning methods to reverse the wettability alteration of mixed-wet cores caused by contact with these SBM components; and (3) to develop new approaches to restoration of wetting that will permit the use of cores drilled with SBM formulations for valid studies of reservoir properties.

  17. Polymer stretch in two-phase microfluidics: Effect of wall wettability

    PubMed Central

    Hu, Ssu-Wei; Sheng, Yu-Jane; Tsao, Heng-Kwong

    2012-01-01

    Polymer stretching in two-phase microfluidics is investigated by dissipative particle dynamics. The flow patterns can be controlled by wall wettability, flowrate ratio between two phases, and Reynolds number (Re). For neutral and partially wettable walls, segmented flows are formed and polymer stretching can be controlled by Re and segment length. At high Re, stratified flows are observed and the extension ratio can be tuned by the flowrate ratio. For nonwettable walls, slug flows are formed and polymer stretching can be controlled by Re and slug length. At high Re or flowrate ratio, annular flows are observed and high extension ratio can be easily attained. PMID:23762212

  18. Ion guiding in curved glass capillaries

    NASA Astrophysics Data System (ADS)

    Kojima, Takao M.; Ikeda, Tokihiro; Kanai, Yasuyuki; Yamazaki, Yasunori

    2015-07-01

    Straight and curved glass capillaries were tested for the guiding of 8 keV Ar8+ ion beams. The straight capillary was about 50 mm long and 0.87 mm/1.1 mm in inner/outer diameter. One of the two curved capillaries was similar, but was curved with a 270 mm radius. The other was 53 mm long, had diameters of 2.34 mm/2.99 mm, and was curved with a 150 mm radius. The corresponding bending angles of the two curved capillaries were 9.6 and 17.5, respectively. Transmission through the straight capillary disappeared when the tilt angle was larger than 5. The curved capillaries guided the ion beams into their corresponding bending angles, which were much larger than 5, with transmission efficiencies of a few tens percent. This demonstrates the possibility of developing a new scheme of simple small beam deflectors and related beam optics.

  19. Capillary pumped loop body heat exchanger

    NASA Technical Reports Server (NTRS)

    Swanson, Theodore D. (Inventor); Wren, deceased, Paul (Inventor)

    1998-01-01

    A capillary pumped loop for transferring heat from one body part to another body part, the capillary pumped loop comprising a capillary evaporator for vaporizing a liquid refrigerant by absorbing heat from a warm body part, a condenser for turning a vaporized refrigerant into a liquid by transferring heat from the vaporized liquid to a cool body part, a first tube section connecting an output port of the capillary evaporator to an input of the condenser, and a second tube section connecting an output of the condenser to an input port of the capillary evaporator. A wick may be provided within the condenser. A pump may be provided between the second tube section and the input port of the capillary evaporator. Additionally, an esternal heat source or heat sink may be utilized.

  20. Microfluidic PMMA interfaces for rectangular glass capillaries

    NASA Astrophysics Data System (ADS)

    Evander, Mikael; Tenje, Maria

    2014-02-01

    We present the design and fabrication of a polymeric capillary fluidic interface fabricated by micro-milling. The design enables the use of glass capillaries with any kind of cross-section in complex microfluidic setups. We demonstrate two different designs of the interface; a double-inlet interface for hydrodynamic focusing and a capillary interface with integrated pneumatic valves. Both capillary interfaces are presented together with examples of practical applications. This communication shows the design optimization and presents details of the fabrication process. The capillary interface opens up for the use of complex microfluidic systems in single-use glass capillaries. They also enable simple fabrication of glass/polymer hybrid devices that can be beneficial in many research fields where a pure polymer chip negatively affects the device's performance, e.g. acoustofluidics.

  1. DNA Sequencing Using capillary Electrophoresis

    SciTech Connect

    Dr. Barry Karger

    2011-05-09

    The overall goal of this program was to develop capillary electrophoresis as the tool to be used to sequence for the first time the Human Genome. Our program was part of the Human Genome Project. In this work, we were highly successful and the replaceable polymer we developed, linear polyacrylamide, was used by the DOE sequencing lab in California to sequence a significant portion of the human genome using the MegaBase multiple capillary array electrophoresis instrument. In this final report, we summarize our efforts and success. We began our work by separating by capillary electrophoresis double strand oligonucleotides using cross-linked polyacrylamide gels in fused silica capillaries. This work showed the potential of the methodology. However, preparation of such cross-linked gel capillaries was difficult with poor reproducibility, and even more important, the columns were not very stable. We improved stability by using non-cross linked linear polyacrylamide. Here, the entangled linear chains could move when osmotic pressure (e.g. sample injection) was imposed on the polymer matrix. This relaxation of the polymer dissipated the stress in the column. Our next advance was to use significantly lower concentrations of the linear polyacrylamide that the polymer could be automatically blown out after each run and replaced with fresh linear polymer solution. In this way, a new column was available for each analytical run. Finally, while testing many linear polymers, we selected linear polyacrylamide as the best matrix as it was the most hydrophilic polymer available. Under our DOE program, we demonstrated initially the success of the linear polyacrylamide to separate double strand DNA. We note that the method is used even today to assay purity of double stranded DNA fragments. Our focus, of course, was on the separation of single stranded DNA for sequencing purposes. In one paper, we demonstrated the success of our approach in sequencing up to 500 bases. Other application papers of sequencing up to this level were also published in the mid 1990's. A major interest of the sequencing community has always been read length. The longer the sequence read per run the more efficient the process as well as the ability to read repeat sequences. We therefore devoted a great deal of time to studying the factors influencing read length in capillary electrophoresis, including polymer type and molecule weight, capillary column temperature, applied electric field, etc. In our initial optimization, we were able to demonstrate, for the first time, the sequencing of over 1000 bases with 90% accuracy. The run required 80 minutes for separation. Sequencing of 1000 bases per column was next demonstrated on a multiple capillary instrument. Our studies revealed that linear polyacrylamide produced the longest read lengths because the hydrophilic single strand DNA had minimal interaction with the very hydrophilic linear polyacrylamide. Any interaction of the DNA with the polymer would lead to broader peaks and lower read length. Another important parameter was the molecular weight of the linear chains. High molecular weight (> 1 MDA) was important to allow the long single strand DNA to reptate through the entangled polymer matrix. In an important paper, we showed an inverse emulsion method to prepare reproducibility linear polyacrylamide polymer with an average MWT of 9MDa. This approach was used in the polymer for sequencing the human genome. Another critical factor in the successful use of capillary electrophoresis for sequencing was the sample preparation method. In the Sanger sequencing reaction, high concentration of salts and dideoxynucleotide remained. Since the sample was introduced to the capillary column by electrokinetic injection, these salt ions would be favorably injected into the column over the sequencing fragments, thus reducing the signal for longer fragments and hence reading read length. In two papers, we examined the role of individual components from the sequencing reaction and then developed a protocol to reduce the deleterious salts. We demonstrated a robust method for achieving long read length DNA sequencing. Continuing our advances, we next demonstrated the achievement of over 1000 bases in less than one hour with a base calling accuracy of between 98 and 99%. In this work, we implemented energy transfer dyes which allowed for cleaner differentiation of the 4 dye labeled terminal nucleotides. In addition, we developed improved base calling software to help read sequencing when the separation was only minimal as occurs at long read lengths. Another critical parameter we studied was column temperature. We demonstrated that read lengths improved as the column temperature was increased from room temperature to 60 C or 70 C. The higher temperature relaxed the DNA chains under the influence of the high electric field.

  2. Malpighi and the discovery of capillaries.

    PubMed

    Pearce, J M S

    2007-01-01

    Leonardo da Vinci clearly observed and described capillaries. Using the microscope, Marcello Malpighi examined the brain and major organs to demonstrate their finer anatomical features. This led to his discovery in 1661, of capillaries that proved fundamental to our understanding of the vascular system in the brain and cord. He hypothesized that capillaries were the connection between arteries and veins that allowed blood to flow back to the heart in the circulation of the blood, as first asserted by William Harvey. PMID:17851250

  3. Microlithographic wet chemical processing in a capillary space

    NASA Astrophysics Data System (ADS)

    Morgan, Russell

    1994-05-01

    The patented device and procedure described provide a method of processing the flat, thin-film coated surfaces encountered in the ultraclean manufacture of integrated circuit wafers, photomasks, panel displays or other similar substrates. The device provides a means of delivering liquids and vapors to those surfaces while temperature, evaporation and particulate contamination are controlled as a natural consequent of its physical configuration. The essential mechanism exploits the surface tension of liquids and the differences in the wettability of surfaces. By juxtaposing the target surface with a prepared surface on the processing device and maintaining a separation of a few millimeters, the gap formed provides a reaction space into which liquids are easily distributed exploiting so-called capillary behavior. While placing the liquid reagent on the hydrophobic, horizontal surface of the processor, the hydrophilic substrate surface suspended above it is transported laterally. The substrate surface then engages the liquid edge which, driven by its own surface tension, quickly fills the gap. The ending of the reaction and removal of the liquid is effected by further transporting the substrate with its captive liquid reactants to a trench provided in the processor surface where the liquid flows down and away. Thus, the processor surface is seen as a series of 'mesas' allowing a sequence of wet process, rinse and vapor treatments, all with the simple lateral movement of the substrate. The effects of improved reaction kinetics on process precision as well as the benefits mentioned above are discussed and compared to previous immersion and spin methods. Critical dimension measurement data are presented from large photomask substrates processed by the instrument.

  4. Hydrodynamics of nanoscopic capillary waves.

    PubMed

    Delgado-Buscalioni, R; Chacon, E; Tarazona, P

    2008-09-01

    The dynamics of nanoscopic capillary waves on simple liquid surfaces is analyzed using molecular dynamics simulations. Each Fourier mode of the surface is obtained from the molecular positions, and its time behavior compared with the hydrodynamic prediction. We trace the transition from propagating to overdamped modes, at short wavelengths. The damping rate is in very good agreement with the hydrodynamic theory up to surprisingly small wavelengths, of about four molecular diameters, but only if the wave number dependent surface tension is considered. At shorter scales, surface tension hydrodynamics break down and we find a transition to a molecular diffusion regime. PMID:18851230

  5. High pressure pulsed capillary viscometry

    NASA Technical Reports Server (NTRS)

    Smith, R. L.; Walowitt, J. A.; Pan, C. H. T.

    1972-01-01

    An analytical and test program was conducted in order to establish the feasibility of a multichamber pulsed-capillary viscometer. The initial design incorporated a piston, ram, and seals which produced measured pulses up to 30,000 psi in the closed chamber system. Pressure pulses from one to ten milliseconds were investigated in a system volume of 1 cuin. Four test fluids: a MIL-L-7808, a 5P4E polyphenyl ether, a MIL-L-23699A, and a synthetic hydrocarbon were examined in the test pressure assembly. The pressure-viscosity coefficient and viscosity delay time were determined for the MIL-L-7808 lubricant tested.

  6. Influence of surface wettability on competitive protein adsorption and initial attachment of osteoblasts.

    PubMed

    Wei, Jianhua; Igarashi, Toshio; Okumori, Naoto; Igarashi, Takayasu; Maetani, Takashi; Liu, Baolin; Yoshinari, Masao

    2009-08-01

    This study investigated the influence of surface wettability on competitive protein adsorption and the initial attachment of osteoblasts. A thin-film coating of hexamethyldisiloxane (HMDSO) and subsequent O(2)-plasma treatment was carried out on substrates with a mirror surface in order to create a wide range of wettabilities. The adsorption behavior of fibronectin (Fn) and albumin (Alb) in both individual and competitive mode, and the initial attachment of mouse osteoblastic cells (MC3T3-E1) over a wide range of wettabilities were investigated. The contact angle of HMDSO coatings without O(2)-plasma treatment against double-distilled water was more than 100 degrees, whereas it dramatically decreased after the O(2)-plasma treatment to almost 0 degrees, resulting in super-hydrophilicity. Individually, Fn adsorption showed a biphasic inclination, whereas Alb showed greater adsorption to hydrophobic surfaces. In the competitive mode, in a solution containing both Fn and Alb, Fn showed greater adsorption on hydrophilic surfaces, whereas Alb predominantly adsorbed on hydrophobic surfaces. The initial attachment of osteoblastic cells increased with an increase in surface wettability, in particular, on a super-hydrophilic surface, which correlated well with Fn adsorption in the competitive mode. These results suggest that Fn adsorption may be responsible for increasing cell adhesion on hydrophilic surfaces in a body fluid or culture media under physiological conditions. PMID:19525576

  7. Bioinspired conical copper wire with gradient wettability for continuous and efficient fog collection.

    PubMed

    Ju, Jie; Xiao, Kai; Yao, Xi; Bai, Hao; Jiang, Lei

    2013-11-01

    Inspired by the efficient fog collection on cactus spines, conical copper wires with gradient wettability are fabricated through gradient electrochemical corrosion and subsequent gradient chemical modification. These dual-gradient copper wires' fog-collection ability is demonstrated to be higher than that of conical copper wires with pure hydrophobic surfaces or pure hydrophilic surfaces, and the underlying mechanism is also analyzed. PMID:24038211

  8. Surface roughness and wettability of dentin ablated with ultrashort pulsed laser.

    PubMed

    Liu, Jing; L, Peijun; Sun, Yuchun; Wang, Yong

    2015-05-01

    The aim of this study was to evaluate the surface roughness and wettability of dentin following ultrashort pulsed laser ablation with different levels of fluence and pulse overlap (PO). Twenty-five extracted human teeth crowns were cut longitudinally into slices of approximately 1.5-mm thick and randomly divided into nine groups of five. Samples in groups 1 to 8 were ablated with an ultrashort pulsed laser through a galvanometric scanning system. Samples in group 9 were prepared using a mechanical rotary instrument. The surface roughness of samples from each group was then measured using a three-dimensional profile measurement laser microscope, and wettability was evaluated by measuring the contact angle of a drop of water on the prepared dentin surface using an optical contact angle measuring device. The results showed that both laser fluence and PO had an effect on dentin surface roughness. Specifically, a higher PO decreased dentin surface roughness and reduced the effect of high-laser fluence on decreasing the surface roughness in some groups. Furthermore, all ablated dentin showed a contact angle of approximately 0 deg, meaning that laser ablation significantly improved wettability. Adjustment of ultrashort pulsed laser parameters can, therefore,significantly alter dentin surface roughness and wettability. PMID:26018789

  9. Novel Convenient Method to Determine Wettability and Dispersibility of Dairy Powders.

    PubMed

    Lee, Jeae; Chai, Changhoon; Park, Dong June; Lim, Kwangsei; Imm, Jee-Young

    2014-01-01

    This study was carried out to develop a simple, convenient, and reproducible testing device to determine wettability and dispersibility of dairy powders. The testing device consists of a sieve (150 ?m) attached to a sample chamber, sensors mounted on a supporting body and a main control unit containing a display panel. The sensors detect the difference in electrical resistance between air and water. A timer is automatically triggered by the sensor when the bottom of sample-loaded chamber contacts water in the petri dish. Wettability and dispersibility of commercial skim milk powders (SMPs) produced at different heating strengths (low-, medium-, and high-heat SMP) are compared using the new testing device. Wettability of the SMPs were correlated with particle size and are found to increase in the order of medium-, low-, and high-heat SMP regardless of the amount of sample tested. Dispersibility of SMPs showed the same trend and high heat-SMP which has the smallest particle size resulted in the lowest dispersibility. Unlike existing methods, the new testing device can determine both wettability and dispersibility of powders and successfully detected differences among the samples. PMID:26761684

  10. Surfactant and irrigation effects on wettable soils: Runoff, erosion, and water retention responses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surfactants are chemical compounds that change the contact angle of water on solid surfaces and are commonly used to increase infiltration into hydrophobic soil. Since production fields with water-repellent soil often contain areas of wettable soil, surfactants applied to such fields will likely be ...

  11. Surface roughness and wettability of dentin ablated with ultrashort pulsed laser

    NASA Astrophysics Data System (ADS)

    Liu, Jing; L, Peijun; Sun, Yuchun; Wang, Yong

    2015-05-01

    The aim of this study was to evaluate the surface roughness and wettability of dentin following ultrashort pulsed laser ablation with different levels of fluence and pulse overlap (PO). Twenty-five extracted human teeth crowns were cut longitudinally into slices of approximately 1.5-mm thick and randomly divided into nine groups of five. Samples in groups 1 to 8 were ablated with an ultrashort pulsed laser through a galvanometric scanning system. Samples in group 9 were prepared using a mechanical rotary instrument. The surface roughness of samples from each group was then measured using a three-dimensional profile measurement laser microscope, and wettability was evaluated by measuring the contact angle of a drop of water on the prepared dentin surface using an optical contact angle measuring device. The results showed that both laser fluence and PO had an effect on dentin surface roughness. Specifically, a higher PO decreased dentin surface roughness and reduced the effect of high-laser fluence on decreasing the surface roughness in some groups. Furthermore, all ablated dentin showed a contact angle of approximately 0 deg, meaning that laser ablation significantly improved wettability. Adjustment of ultrashort pulsed laser parameters can, therefore, significantly alter dentin surface roughness and wettability.

  12. Investigation of wettability by NMR microscopy and spin-lattice relaxation

    SciTech Connect

    Doughty, D.A.; Tomutsa, Liviu

    1993-11-01

    The wettability of reservoir rock has an important impact on the efficiency of oil recovery processes and the distribution of oil and water within the reservoir. One of the potentially useful tools for wettability measurements is nuclear magnetic resonance (NMR) and spin-lattice relaxation. More recently using NMR microscopy NIPER has developed the capability of imaging one- and two-phase fluid systems in reservoir rock at resolutions to 25 microns. Effects seen in the images of fluids within the pore space of rocks near the rock grain surfaces hinted at the possibility of using NMR microscopy to map the wettability variations at grain sites within the pore space. Investigations were begun using NMR microscopy and spin-lattice relaxation time measurements on rock/fluid systems and on well-defined fractional wet model systems to study these effects. Relaxation data has been modelled using the stretched exponential relationship recently introduced. Comparisons of the NMR microscopy results of the model system with the rock results indicate that the observed effects probably do not reflect actual wettability variations within the pore space. The results of the relaxation time measurements reveal that even in the simple model studied, the behavior of two phases is somewhat ambiguous and much more complex and requires more study.

  13. Femtosecond laser induced hierarchical ZnO superhydrophobic surfaces with switchable wettability.

    PubMed

    Yong, Jiale; Chen, Feng; Yang, Qing; Fang, Yao; Huo, Jinglan; Hou, Xun

    2015-06-18

    A simple and one-step method to form a rough ZnO layer consisting of micro/nanoscale hierarchical structures via direct femtosecond laser ablation of the Zn surface is reported for the first time. The resultant surfaces show switchable wettability between superhydrophobicity and quasi-superhydrophilicity via alternate UV irradiation and dark storage. PMID:25987485

  14. Multifunctional superamphiphobic TiO2 nanostructure surfaces with facile wettability and adhesion engineering.

    PubMed

    Huang, Jian-Ying; Lai, Yue-Kun; Pan, Fei; Yang, Lei; Wang, Hui; Zhang, Ke-Qin; Fuchs, Harald; Chi, Li-Feng

    2014-12-10

    Compared to conventional top-down photo-cleavage method, a facile bottom-up ink-combination method to in situ and rapidly achieve water wettability and adhesion transition, with a great contrast on the superamphiphobic TiO2 nanostructured film, is described. Moreover, such combination method is suitable for various kinds of superamphiphobic substrate. Oil-based ink covering or removing changes not only the topographical morphology but also surface chemical composition, and these resultant topographical morphology and composition engineering realize the site-selectively switchable wettability varying from superamphiphobicity to amphiphilicity, and water adhesion between sliding superamphiphobicity and sticky superamphiphobicity in micro-scale. Additionally, positive and negative micro-pattern can be achieved by taking advantage of the inherent photocatalytic property of TiO2 with the assistance of anti-UV light ink mask. Finally, the potential applications of the site-selectively sticky superamphiphobic surface were demonstrated. In a proof-of-concept study, the microdroplet manipulation (storage, moving, mixing, and transfer), specific gas sensing, wettability template for positive and negative ZnO patterning, and site-selective cell immobilization have been demonstrated. This study will give an important input to the field of advanced functional material surfaces with special wettability. PMID:25070619

  15. Effect of surface wettability on carbon nanotube water-based nanofluid droplet impingement heat transfer

    NASA Astrophysics Data System (ADS)

    Jackson, Robert Gordon; Kahani, Mostafa; Karwa, Nitin; Wu, Alex; Lamb, Robert; Taylor, Robert; Rosengarten, Gary

    2014-07-01

    Recent studies into droplet impingement heat transfer have demonstrated that it has great potential for providing high heat flux cooling in areas such as thermal management of electronics. The wettability of the surface affects the flow dynamics of the impingement process and the resulting heat transfer. In this study, the effect of surface wettability on carbon nanotube water-based nanofluid droplet impingement heat transfer has been studied and compared with water. Superhydrophobic or hydrophilic coatings are applied on one face of monocrystalline silicon wafers (the drop impinges on this face) while the other face is painted matt black to permit infrared thermography. The silicon wafer is preheated to 40 C and a single droplet impinges normally on the top facing coated surface of the monocrystalline silicon wafer. The inverse heat conduction problem has been solved using the measured black face temperature. For both the water and nanofluid droplets, the convective heat transfer coefficient reduces with the decrease in surface wettability. It is found that the nanofluid produce a significantly higher convective heat transfer coefficient during droplet impingement than water, with the enhancement increasing with increasing wettability.

  16. The impact of wettability and connectivity on relative permeability in carbonates: A pore network modeling analysis

    NASA Astrophysics Data System (ADS)

    Gharbi, Oussama; Blunt, Martin J.

    2012-12-01

    We use pore network modeling to study the impact of wettability and connectivity on waterflood relative permeability for a set of six carbonate samples. Four quarry samples are studied, Indiana, Portland, Guiting, and Mount Gambier, along with two subsurface samples obtained from a deep saline Middle Eastern aquifer. The pore space is imaged in three dimensions using X-ray microtomography at a resolution of a few microns. The images are segmented into pore and solid, and a topologically representative network of pores and throats is extracted from these images. We then simulate quasi-static displacement in the networks. We represent mixed-wet behavior by varying the oil-wet fraction of the pore space. The relative permeability is strongly dependent on both the wettability and the average coordination number of the network. We show that traditional measures of wettability based on the point where the relative permeability curves cross are not reliable. Good agreement is found between our calculations and measurements of relative permeability on carbonates in the literature. This work helps establish a library of benchmark samples for multiphase flow and transport computations. The implications of the results for field-scale displacement mechanisms are discussed, and the efficiency of waterflooding as an oil recovery process in carbonate reservoirs is assessed depending on the wettability and pore space connectivity.

  17. Enhanced wettability performance of ultrathin ZnO nanotubes by coupling morphology and size effects

    NASA Astrophysics Data System (ADS)

    Yang, Peihua; Wang, Kun; Liang, Zhiwen; Mai, Wenjie; Wang, Cheng-Xin; Xie, Weiguang; Liu, Pengyi; Zhang, Long; Cai, Xiang; Tan, Shaozao; Song, Jinhui

    2012-08-01

    In this work, we report on the detailed characterization and mechanism analysis of the improved wettability performance of a new type of ZnO nanostructure, the ultrathin ZnO nanotube, whose growth is induced by screw-dislocation. The newly discovered enhanced wettability properties are suggested to be caused by coupling the morphology and size effects of the nanostructured surface. These ultrathin nanotubes with low density and small dimension form a wet-hair-like hierarchical morphology, which shows a further improved superhydrophobic property with an 8.6 +/- 1.6° larger contact angle than that of ZnO nanorods due to the morphology effect. In addition, owing to the large surface to volume ratio and increased effective UV-irradiated area of the ultrathin tubular structure, the ZnO nanotubes exhibit ~5 times faster superhydrophobicity to superhydrophilicity conversion speed than nanorods under 254 nm UV illumination. Furthermore, UV light with a wavelength of 254 nm exhibits ~40 times faster wettability conversion speed for nanotubes than that of 365 nm, which is suggested to be a result of the band gap shift at the nanoscale. The combined advantages of enhanced superhydrophobicity, improved sensitivity, and faster conversion speed by coupling morphology and size effects of these ZnO nanotubes should give them broad applications in self-cleaning surfaces and wettability switches.

  18. Thermal Annealing Treatment to Achieve Switchable and Reversible Wettability on ZnO Nanowires Surface

    NASA Astrophysics Data System (ADS)

    Liu, Changsong; Zheng, Dongmei; Zhou, Jigen; Wan, Yong; Li, Zhiwen

    2011-06-01

    Zinc oxide (ZnO) nanostructured surfaces can be reversibly altered from hydrophobicity to hydrophilicity in response to ultraviolet light or plasma treatment. In this paper, a thermal annealing procedure was used to tune ZnO nanowires' surface wettability, and the switchable reversible wettability was achieved. ZnO nanowires were synthesized by a simple solution method. The surfaces of as-synthesized ZnO nanowires demonstrated a superhydrophobicity with water contact angle of 151. After a high temperature treatment (>300C) for 20 minutes, their superhydrophobicity was transited to superhydrophilicity with water contact angle of < 10. It was noted that this transition was very short (less than half minutes) when the annealing temperature is more than 400 C. The high-thermal annealed superhydrophilic ZnO surfaces were recovered to superhydrophobicity after a low-temperature (~100 C) procedure in 4 days. Thus, the tunable properties of ZnO surface energy result in reversible wettability between superhydrophobicity and superhydrophilicity. This tunable wettability can be explained based on ZnO as a semiconductor material, which provides different numbers of oxygen vacancies under different temperatures. This result will extend applications of ZnO nanomaterials to many important fields, such as microfluidic devices, chemical sensors and biosensors.

  19. Surfactant and Irrigation Effects on Runoff, Erosion, and Water Retention of Three Wettable Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surfactants are chemical compounds that change the contact angle of water on solid surfaces and are commonly used to increase infiltration into hydrophobic soil. Since production fields with water-repellent soil often contain areas of wettable soil, surfactants applied to such fields will likely be ...

  20. Novel Convenient Method to Determine Wettability and Dispersibility of Dairy Powders

    PubMed Central

    Park, Dong June; Lim, Kwangsei

    2014-01-01

    This study was carried out to develop a simple, convenient, and reproducible testing device to determine wettability and dispersibility of dairy powders. The testing device consists of a sieve (150 ?m) attached to a sample chamber, sensors mounted on a supporting body and a main control unit containing a display panel. The sensors detect the difference in electrical resistance between air and water. A timer is automatically triggered by the sensor when the bottom of sample-loaded chamber contacts water in the petri dish. Wettability and dispersibility of commercial skim milk powders (SMPs) produced at different heating strengths (low-, medium-, and high-heat SMP) are compared using the new testing device. Wettability of the SMPs were correlated with particle size and are found to increase in the order of medium-, low-, and high-heat SMP regardless of the amount of sample tested. Dispersibility of SMPs showed the same trend and high heat-SMP which has the smallest particle size resulted in the lowest dispersibility. Unlike existing methods, the new testing device can determine both wettability and dispersibility of powders and successfully detected differences among the samples.

  1. Surfactant Effects on the Water-stable Aggregation of Wettable and Nonwettable Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Surfactants may affect soil structure differently, depending upon a soil’s wettability or the quality of rainfall or irrigation water. This study evaluated the effects of two nonionic surfactants and a surfactant-free water control on the water drop penetration time (WDPT) and mean weight diameter ...

  2. Pharmacological effects of various venoms on cutaneous capillary leakage.

    PubMed

    Burnett, J W; Calton, G J

    1986-01-01

    Studies to counteract the cutaneous vasopermeability actions of a wasp (Vespa orientalis), an anemone (Bolocera tuediae) and three jellyfish (Chironex fleckeri, Chrysaora quinquecirrha and Physalia physalis) venoms were conducted by using various pharmacological antagonists. Piripost (a leukotriene inhibitor) reduced vasopermeability if administered 5 min prior to challenge with the jellyfish venoms. Methysergide counteracted the vasopermeability of three of four coelenterate venoms, whereas indomethacin was effective against capillary leakage induced by Chironex venom. These studies indicate that anti-dermonecrotic therapy against various venoms will have to be species-specific. PMID:2875548

  3. Treatment of septic tank effluents by a full-scale capillary seepage soil biofiltration system.

    PubMed

    Fan, Chihhao; Chang, Fang-Chih; Ko, Chun-Han; Teng, Chia-Ji; Chang, Tzi-Chin; Sheu, Yiong-Shing

    2009-03-01

    The purpose of this study is to evaluate the efficiency of septic tank effluent treatment by an underground capillary seepage soil biofiltration system in a suburban area of Taipei, Taiwan. In contrast to traditional subsurface wastewater infiltration systems, capillary seepage soil biofiltration systems initially draw incoming influent upwards from the distribution pipe by capillary and siphonage actions, then spread influent throughout the soil biofiltration bed. The underground capillary seepage soil biofiltration system consists of a train of underground treatment units, including one wastewater distribution tank, two capillary seepage soil biofiltration units in series, and a discharge tank. Each capillary seepage soil biofiltration unit contains one facultative digestion tank and one set of biofiltration beds. At the flow rate of 50 m3/day, average influent concentrations of biochemical oxygen demand (BOD), suspended solid (SS), ammonia nitrogen (NH3-N), and total phosphates (TP), were 36.15 mg/L, 29.14 mg/L, 16.05 mg/L, and 1.75 mg/L, respectively. After 1.5 years of system operation, the measured influent and effluent results show that the treatment efficiencies of the soil biofiltration system for BOD, SS, NH3-N, TP, and total coliforms are 82.96%, 60.95%, 67.17%, 74.86%, and 99.99%, respectively. PMID:19326671

  4. Evaluation of capillary reinforced composites

    NASA Technical Reports Server (NTRS)

    Cahill, J. E.; Halase, J. F.; South, W. K.; Stoffer, L. J.

    1985-01-01

    Anti-icing of the inlet of jet engines is generally performed with high pressure heated air that is directed forward from the compressor through a series of pipes to various manifolds located near the structures to be anti-iced. From these manifolds, the air is directed to all flowpath surfaces that may be susceptible to ice formation. There the anti-icing function may be performed by either heat conduction or film heating. Unfortunately, the prospect of utilizing lighweight, high strength composites for inlet structures of jet engines has been frustrated by the low transverse thermal conductivity of such materials. It was the objective of this program to develop an advanced materials and design concept for anti-icing composite structures. The concept that was evaluated used capillary glass tubes embedded on the surface of a composite structure with heated air ducted through the tubes. An analytical computer program was developed to predict the anti-icing performance of such tubes and a test program was conducted to demonstrate actual performance of this system. Test data and analytical code results were in excellent agreement. Both indicate feasibility of using capillary tubes for surface heating as a means for composite engine structures to combat ice accumulation.

  5. Wettability and Oil Recovery by Imbibition and Viscous Displacement from Fractured and Heterogeneous Carbonates

    SciTech Connect

    Norman R. Morrow; Jill Buckley

    2006-04-01

    About one-half of U.S. oil reserves are held in carbonate formations. The remaining oil in carbonate reservoirs is regarded as the major domestic target for improved oil recovery. Carbonate reservoirs are often fractured and have great complexity even at the core scale. Formation evaluation and prediction is often subject to great uncertainty. This study addresses quantification of crude oil/brine/rock interactions and the impact of reservoir heterogeneity on oil recovery by spontaneous imbibition and viscous displacement from pore to field scale. Wettability-alteration characteristics of crude oils were measured at calcite and dolomite surfaces and related to the properties of the crude oils through asphaltene content, acid and base numbers, and refractive index. Oil recovery was investigated for a selection of limestones and dolomites that cover over three orders of magnitude in permeability and a factor of four variation in porosity. Wettability control was achieved by adsorption from crude oils obtained from producing carbonate reservoirs. The induced wettability states were compared with those measured for reservoir cores. The prepared cores were used to investigate oil recovery by spontaneous imbibition and viscous displacement. The results of imbibition tests were used in wettability characterization and to develop mass transfer functions for application in reservoir simulation of fractured carbonates. Studies of viscous displacement in carbonates focused on the unexpected but repeatedly observed sensitivity of oil recovery to injection rate. The main variables were pore structure, mobility ratio, and wettability. The potential for improved oil recovery from rate-sensitive carbonate reservoirs by increased injection pressure, increased injectivity, decreased well spacing or reduction of interfacial tension was evaluated.

  6. Wettability of terminally anchored polymer brush layers on a polyamide surface.

    PubMed

    Varin, Kari J Moses; Cohen, Yoram

    2014-12-15

    Surface wettability of terminally anchored hydrophilic polymer brush layers on polyamide-silicon (PA-Si) surfaces was evaluated with respect to surface topography at the nanoscale. Hydrophilic polyvinylpyrrolidone (PVP) and polyacrylamide (PAAm) brush layers were synthesized via graft polymerization onto a PA-Si surface previously activated by surface treatment with atmospheric pressure plasma. Hydrophilicity (or wettability) of the PA substrate, as quantified by the free energy of hydration, was increased upon surface coverage with the PVP and PAAm brush layers by 13-24% (-101.4 to -111.3 mJ/m(2)) and 19-37% (-106.1 to -122.4 mJ/m(2)), respectively. Surface hydrophilicity increased with both increasing surface roughness (0.55-2.89 nm and 1.54-5.84 nm for PVP and PAAm, respectively) and polymer volume (1.3×10(6)-7.3×10(6) nm(3)/μm(2) and 3.3×10(6)-2.8×10(7) nm(3)/μm(2) for PVP and PAAm surfaces, respectively). The present study suggests that a specific level of surface wettability can be attained by tailor-designing the polymer brush layer's physicochemical characteristics (e.g., surface roughness, wettability, and polymer water affinity) by adjusting surface topography and surface chemistry, which are controlled by surface activation and polymerization conditions. The above indicates that there is merit in structuring various surfaces with hydrophilic brush layers to increase surface wettability in membrane filtration, biomedical devices, and lubrication applications. PMID:25305445

  7. Microbial Enhanced Oil Recovery and Wettability Research Program. Annual report, FY 1991

    SciTech Connect

    Bala, G.A.; Barrett, K.B.; Eastman, S.L.; Herd, M.D.; Jackson, J.D.; Robertson, E.P.; Thomas, C.P.

    1993-09-01

    This report covers research results for fiscal year 1991 for the Microbial Enhanced Oil Recovery (MEOR) and Wettability Research Program conducted by EG&G Idaho, Inc. at the Idaho National Engineering Laboratory ONEL) for the US Department of Energy Idaho Field Office (DOE-ID). The program is funded by the Assistant Secretary of Fossil Energy, and managed by DOE-ID and the Bartlesville Project Office (BPO). The objectives of this multi-year program are to develop MEOR systems for application to reservoirs containing medium to heavy crude oils and to design and implement an industry cost-shared field demonstration project of the developed technology. An understanding of the controlling mechanisms will first be developed through the use of laboratory scale testing to determine the ability of microbially mediated processes to recover oil under reservoir conditions and to develop the design criteria for scale-up to the field. Concurrently with this work, the isolation and characterization of microbial species collected from various locations including target oil field environments is underway to develop more effective oil recovery systems for specific applications. Research focus includes the study of biogenic product and formation souring processes including mitigation and prevention. Souring research performed in FY 1991 also included the development of microsensor probe technology for the detection of total sulfide in collaboration with the Montana State University Center for Interfacial Microbial Process Engineering (CIMPE). Wettability research is a multi-year collaborative effort with the New Mexico Petroleum Recovery Research Center (NMPRRC) at the New Mexico institute of Mining and Technology, Socorro, NM to evaluate reservoir wettability and its effects on oil recovery. Results from the wettability research will be applied to determine if alteration of wettability is a significant contributing mechanism for MEOR systems.

  8. Sheathless interface for coupling capillary electrophoresis with mass spectrometry

    SciTech Connect

    Wang, Chenchen; Tang, Keqi; Smith, Richard D.

    2014-06-17

    A sheathless interface for coupling capillary electrophoresis (CE) with mass spectrometry is disclosed. The sheathless interface includes a separation capillary for performing CE separation and an emitter capillary for electrospray ionization. A portion of the emitter capillary is porous or, alternatively, is coated to form an electrically conductive surface. A section of the emitter capillary is disposed within the separation capillary, forming a joint. A metal tube, containing a conductive liquid, encloses the joint.

  9. Capillary gas chromatography of lupin alkaloids.

    PubMed

    Priddis, C R

    1983-05-20

    The resolution and identification of twelve lupin alkaloids are demonstrated using capillary gas chromatography and gas chromatography-mass spectrometry. The quantitative capabilities of capillary gas chromatography are illustrated by specific reference to the four major alkaloids of lupinus angustifolius, namely lupanine, 13-hydroxylupanine, augustifoline and alpha-isolupanine. PMID:6874800

  10. Streptomycetes can grow through small filter capillaries.

    PubMed

    Wolf, H; Schoppmann, H

    1989-02-01

    Streptomycetes are Gram-positive bacteria growing as branching filaments. The filaments are able to deform. This ability allows the cells to squeeze through capillaries as small as 0.2 micron in diameter. After passage through the capillaries, numerous hyphae are morphologically altered to a helical structure. PMID:2721918

  11. Wettability of poultry litter biochars at variable pyrolysis temperatures and their impact on soil wettability and water retention relationships

    NASA Astrophysics Data System (ADS)

    Yi, S. C.; Witt, B.; Guo, M.; Chiu, P.; Imhoff, P. T.

    2012-12-01

    To reduce the impact of poultry farming on greenhouse gas emissions, poultry farming waste - poultry litter - can be converted to biofuel and biochar through slow-pyrolysis, with the biochar added to agricultural soil for nutrient enrichment and carbon sequestration. While biochars from source materials other than poultry litter have been shown to sequester carbon and increase soil fertility, there is considerable variability in biochar behavior - even with biochars created from the same source material. This situation is exacerbated by our limited understanding of how biochars alter physical, chemical, and biological processes in agricultural soils. The focus of this work is to develop a mechanistic understanding of how poultry litter (PL) biochars affect the hydrology, microbial communities, N2O emissions, and nitrogen cycling in agricultural soils. The initial focus is on the impact of PL biochar on soil hydrology. PL from Perdue AgriRecycle, LLC (Seaford, Delaware) was used to produce biochars at pyrolysis temperatures from 300°C to 600°C. To explore the impact of these biochars on soil wettability, the PL biochars were mixed with a 30/40 Accusand in mass fractions from 0% to 100%. The water contact angle was then measured using a goniometer on these sand/biochar mixtures using the sessile drop method and a single layer of sample particles. The PL biochars produced at temperatures between 300°C to 400°C were hydrophobic, while those pyrolized at > 400°C were hydrophilic. Water contact angles for samples with 100% biochar varied systematically with pyrolysis temperature, decreasing from 101.12° to 20.57° as the pyrolysis temperature increased from 300 to 600°C. Even for small amounts of hydrophobic biochar added to the hydrophilic sand, the contact angle of the mixture was altered: for sand/biochar mixtures containing only 2% hydrophobic PL biochar by weight, the contact angle of the mixture increased from ~ 8° (0% biochar) to 20° (2% biochar). For higher mass fractions, the impact of hydrophobic PL biochar on the sand/mixture contact angle was more dramatic: for a sand/biochar mixture with 15% PL biochar, the contact angle was 40.12°. Water drop penetration tests were also performed on these samples, and results were consistent with contact angles measured with the sessile drop method. To further explore the cause of the varying contact angle with pyrolysis temperature, the PL biochars were vigorously rinsed with deionized water or heated for 24 hours at 105°C, and the contact angle measurements repeated. Both rinsing and heating samples rendered hydrophobic PL biochar hydrophilic. Rinsate samples were analyzed for total organic carbon and with GC-MS. These data suggest that bio-oils produced during slow-pyrolysis at temperatures < 400°C condensed on biochar and caused hydrophobicity. These bio-oils could be removed through vigorous washing with deionized water or heating to 105°C. The implication of these changes in water contact angle from PL biochar addition on water retention relationships for soil and on water distribution within pores will be discussed.

  12. Isolation of intact capillaries and capillary plasma membranes from frozen human brain.

    PubMed

    Pardridge, W M; Yang, J; Eisenberg, J; Tourtellotte, W W

    1987-01-01

    The development of methods for the isolation of brain capillaries and brain capillary plasma membranes makes possible biochemical studies of the blood-brain barrier (BBB), which is made up of brain capillaries. Studies aimed at assessing the role of the BBB in the pathogenesis of specific neurologic diseases, e.g., Alzheimer's disease or multiple sclerosis, will necessitate the isolation of capillaries from brain involved with specific pathology. Such tissue is most readily available from banks containing frozen human brain. The present studies show that intact capillaries and capillary plasma membranes can be isolated from frozen human brain, including as little as five g of multiple sclerosis plaque tissue. Capillaries from frozen human brain are enriched in gamma-glutamyl transpeptidase, factor VIII antigen, and a 46K protein which has recently been shown to be a BBB-specific protein. These studies provide the basis for future biochemical studies of human brain microvessels in neurologic disease. PMID:3694717

  13. Intracranial capillary hemangioma in an elderly patient

    PubMed Central

    Okamoto, Ai; Nakagawa, Ichiro; Matsuda, Ryosuke; Nishimura, Fumihiko; Motoyama, Yasushi; Park, Young-Su; Nakamura, Mitsutoshi; Nakase, Hiroyuki

    2015-01-01

    Background: Capillary hemangiomas are neoplasms involving skin and soft tissue in infants. These lesions rarely involved an intracranial space and reported age distribution ranges from infancy to middle age. We report an extremely rare case of rapidly rising intracranial capillary hemangioma in an elderly woman. Case Description: The 82-year-old woman presented with vomiting, reduced level of consciousness, and worsening mental state. Computed tomography showed a contrast-enhanced extra-axial lesion in the left frontal operculum, although no intracranial mass lesion was identifiable from magnetic resonance imaging taken 2 years earlier. Complete surgical excision was performed and histopathological examination diagnosed benign capillary hemangioma consisting of a variety of dilated capillary blood vessels lined by endothelial cells. Conclusion: This is the first description of rapid growth of an intracranial capillary hemangioma in an elderly woman. These lesions are exceedingly rare in the elderly population, but still show the capacity for rapid growth. Complete excision would prevent further recurrence. PMID:26664868

  14. Wettability measurement under high P-T conditions using X-ray imaging with application to the brine-supercritical CO2 system

    NASA Astrophysics Data System (ADS)

    Chaudhary, Kuldeep; Guiltinan, Eric J.; Cardenas, M. Bayani; Maisano, Jessica A.; Ketcham, Richard A.; Bennett, Philip C.

    2015-09-01

    We present a new method for measuring wettability or contact angle of minerals at reservoir pressure-temperature conditions using high-resolution X-ray computed tomography (HRXCT) and radiography. In this method, a capillary or a narrow slot is constructed from a mineral or a rock sample of interest wherein two fluids are allowed to form an interface that is imaged using X-rays. After some validation measurements at room pressure-temperature conditions, we illustrate this method by measuring the contact angle of CO2-brine on quartz, muscovite, shale, borosilicate glass, polytetrafluoroethylene (PTFE or Teflon), and polyether ether ketone (PEEK) surfaces at 60-71°C and 13.8-22.8 MPa. At reservoir conditions, PTFE and PEEK surfaces were found to be CO2-wet with contact angles of 140° and 127°, respectively. Quartz and muscovite were found to be water-wet with contact angles of 26° and 58°, respectively, under similar conditions. Borosilicate glass-air-brine at room conditions showed strong water-wet characteristics with a contact angle of 9°, whereas borosilicate glass-CO2-brine at 13.8 MPa and 60°C showed a decrease in its water-wetness with contact angle of 54°. This method provides a new application for X-ray imaging and an alternative to other methods.

  15. Wettability of amorphous and nanocrystalline Fe78B13Si9 substrates by molten Sn and Bi

    PubMed Central

    2011-01-01

    The wettability of amorphous and annealing-induced nanocrystalline Fe78B13Si9 ribbons by molten Sn and Bi at 600 K was measured using an improved sessile drop method. The results demonstrate that the structural relaxation and crystallization in the amorphous substrates do not substantially change the wettability with molten Bi because of their invariable physical interaction, but remarkably deteriorate the wettability and interfacial bonding with molten Sn as a result of changing a chemical interaction to a physical one for the atoms at the interface. PMID:21711852

  16. New concept for coal wettability evaluation and modulation. Technical progress report, January 1, 1994--March 31, 1994

    SciTech Connect

    Hu, W.

    1994-05-01

    This project is concerned with the new concept for coal surface wettability and floatability evaluation and modulation. During this quarter the Hallimond-tube tests were conducted for the three coals, mineral pyrite, and coal pyrite samples. The kinetic floatability of the five samples have been tested without collector, with kerosene and with benzene as collector. The test results indicate that there are good agreements between the experimental observation and the theoretical assumption hypothesis about the new concept of the surface wettability and floatability of the coal and pyrite. These test results also shown that wettability is incompatible with floatability.

  17. Influence of pore morphology and topology on capillary trapping in geological carbon dioxide sequestration

    NASA Astrophysics Data System (ADS)

    Andersson, L.; Harper, E.; Herring, A. L.; Wildenschild, D.

    2012-12-01

    Current carbon capture and storage (CCS) techniques could reduce the release of anthropogenic CO2 into the atmosphere by subsurface sequestration of CO2 in saline aquifers. In geological storage CO2 is injected into deep underground porous formations where CO2 is in the supercritical state. Deep saline aquifers are particularly attractive because of their abundance and potentially large storage volumes. Despite very broad research efforts there are still substantial uncertainties related to the effectiveness of the trapping, dissolution, and precipitation processes controlling the permanent storage of CO2. After injection of CO2 the saline water (brine) will imbibe back and reoccupy the pore space as the CO2 moves upwards, trapping a large part of the CO2. This trapping mechanism is known as capillary trapping and occurs as isolated CO2 bubbles are locked in the brine inside the pores of the porous rock. The large-scale movement of CO2 within the brine is thereby prevented. This mechanism thus constitutes an important storage mechanism after the CO2 injection until the subsequent dissolution trapping and precipitation of carbonate mineral. The capillary trapping of CO2 depends largely on the shape and interconnectivity of the pore space and it is therefore important to study the influence of pore scale morphology and topology to understand and optimize large scale capillary trapping. We use a high pressure set-up, designed for supercritical CO2 conditions, with a flow cell compatible with synchrotron-based X-ray computed micro-tomography (CMT) to generate high-resolution images to study capillary trapping. We use sintered glass bead columns as an approximation for unconsolidated reservoir systems. The smooth surface glass bead data allow us to separate the chemistry and surface roughness effects of the porous medium from the effect of the morphology and topology on the capillary trapping. We will relate these aspects of the pore space to the distribution of the fluids (wetting and non-wetting) and initial and residual non-wetting phase saturations. Potential wettability alteration due to exposure of the beads to supercritical CO2 is also explored by comparing high-pressure and low-pressure experimental results.

  18. Capillary Crack Imbibition: A Theoretical and Experimental Study Using a Hele-Shaw Cell

    NASA Astrophysics Data System (ADS)

    Schütt, H.; Spetzler, H.

    - We study the filling of horizontal cracks with constant aperture driven by capillary forces. The physical model of the crack consists of a narrow gap between two flat glass plates (Hele-Shaw cell). The liquid enters the gap through a hole in the bottom plate. The flow is driven purely by the force acting on the contact lines between solid, liquid, and gas. We developed a theoretical model for this type of flow on the basis of Darcy's law; it allows for the consideration of different surface conditions.We run the experiment for two surface conditions: Surfaces boiled in hydrogen peroxide to remove initial contamination, and surfaces contaminated with 2-propanol after boiling in hydrogen peroxide. The flow rate depends on the gap aperture and on the interaction of the liquid with the air and the solid surfaces: The smaller the aperture, the lower the flow rate due to viscous resistance of the liquid. The flow rate is also reduced when the glass surfaces are contaminated with 2-propanol. The contact line force per unit length is approximately 60% higher on clean glass surfaces than it is on glass surfaces with the 2-propanol contamination. These experimental results are in agreement with our theoretical model and are confirmed by independent measurements of the liquid-solid interaction in capillary rise experiments under static conditions with the same Hele-Shaw cell.Another aspect of this study is the distribution of the liquid for the different surface conditions. The overall shape is a circular disk, as assumed in the theoretical model. However, a pronounced contact line roughness develops in case of the surfaces contaminated with 2-propanol, and air bubbles are trapped behind the contact line. A further analysis of the flow regime using the capillary number and the ratio of the viscosities of the involved fluids (water and air) reveals that the experiments take place in the transition zone between stable displacement and capillary fingering, i.e., neither viscous nor capillary fingers develop under the conditions of the experiment. The contact line roughness and the trapped air bubbles in the contaminated cell reflect local inhomogeneities of the surface wettability.

  19. Two-dimensional capillary origami

    NASA Astrophysics Data System (ADS)

    Brubaker, N. D.; Lega, J.

    2016-01-01

    We describe a global approach to the problem of capillary origami that captures all unfolded equilibrium configurations in the two-dimensional setting where the drop is not required to fully wet the flexible plate. We provide bifurcation diagrams showing the level of encapsulation of each equilibrium configuration as a function of the volume of liquid that it contains, as well as plots representing the energy of each equilibrium branch. These diagrams indicate at what volume level the liquid drop ceases to be attached to the endpoints of the plate, which depends on the value of the contact angle. As in the case of pinned contact points, three different parameter regimes are identified, one of which predicts instantaneous encapsulation for small initial volumes of liquid.

  20. Copolymers For Capillary Gel Electrophoresis

    SciTech Connect

    Liu, Changsheng; Li, Qingbo

    2005-08-09

    This invention relates to an electrophoresis separation medium having a gel matrix of at least one random, linear copolymer comprising a primary comonomer and at least one secondary comonomer, wherein the comonomers are randomly distributed along the copolymer chain. The primary comonomer is an acrylamide or an acrylamide derivative that provides the primary physical, chemical, and sieving properties of the gel matrix. The at least one secondary comonomer imparts an inherent physical, chemical, or sieving property to the copolymer chain. The primary and secondary comonomers are present in a ratio sufficient to induce desired properties that optimize electrophoresis performance. The invention also relates to a method of separating a mixture of biological molecules using this gel matrix, a method of preparing the novel electrophoresis separation medium, and a capillary tube filled with the electrophoresis separation medium.

  1. Capillary Separation: Micellar Electrokinetic Chromatography

    NASA Astrophysics Data System (ADS)

    Terabe, Shigeru

    2009-07-01

    Micellar electrokinetic chromatography (MEKC), a separation mode of capillary electrophoresis (CE), has enabled the separation of electrically neutral analytes. MEKC can be performed by adding an ionic micelle to the running solution of CE without modifying the instrument. Its separation principle is based on the differential migration of the ionic micelles and the bulk running buffer under electrophoresis conditions and on the interaction between the analyte and the micelle. Hence, MEKC's separation principle is similar to that of chromatography. MEKC is a useful technique particularly for the separation of small molecules, both neutral and charged, and yields high-efficiency separation in a short time with minimum amounts of sample and reagents. To improve the concentration sensitivity of detection, several on-line sample preconcentration techniques such as sweeping have been developed.

  2. Gravity Capillary Standing Water Waves

    NASA Astrophysics Data System (ADS)

    Alazard, Thomas; Baldi, Pietro

    2015-09-01

    The paper deals with the 2D gravity-capillary water waves equations in their Hamiltonian formulation, addressing the question of the nonlinear interaction of a plane wave with its reflection off a vertical wall. The main result is the construction of small amplitude, standing (namely periodic in time and space, and not travelling) solutions of Sobolev regularity, for almost all values of the surface tension coefficient, and for a large set of time-frequencies. This is an existence result for a quasi-linear, Hamiltonian, reversible system of two autonomous pseudo-PDEs with small divisors. The proof is a combination of different techniques, such as a Nash-Moser scheme, microlocal analysis and bifurcation analysis.

  3. Capillary Forces in Suspension Rheology

    NASA Astrophysics Data System (ADS)

    Koos, Erin; Willenbacher, Norbert

    2011-02-01

    The rheology of suspensions (solid particles dispersed in a fluid) is controlled primarily through the volume fraction of solids. We show that the addition of small amounts of a secondary fluid, immiscible with the continuous phase of the suspension, causes agglomeration due to capillary forces and creates particle networks, dramatically altering the bulk rheological behavior from predominantly viscous or weakly elastic to highly elastic or gel-like. This universal phenomenon is observed for a rich variety of particle/liquid systems, independent of whether the second liquid wets the particles better or worse than the primary liquid. These admixtures form stable suspensions where settling would otherwise occur and may serve as a precursor for microporous polymer foams, or lightweight ceramics.

  4. Capillary forces in suspension rheology.

    PubMed

    Koos, Erin; Willenbacher, Norbert

    2011-02-18

    The rheology of suspensions (solid particles dispersed in a fluid) is controlled primarily through the volume fraction of solids. We show that the addition of small amounts of a secondary fluid, immiscible with the continuous phase of the suspension, causes agglomeration due to capillary forces and creates particle networks, dramatically altering the bulk rheological behavior from predominantly viscous or weakly elastic to highly elastic or gel-like. This universal phenomenon is observed for a rich variety of particle/liquid systems, independent of whether the second liquid wets the particles better or worse than the primary liquid. These admixtures form stable suspensions where settling would otherwise occur and may serve as a precursor for microporous polymer foams, or lightweight ceramics. PMID:21330542

  5. Technology Solutions Case Study: Capillary Break Beneath a Slab: Polyethylene Sheeting over Aggregate, Southwestern Pennsylvania

    SciTech Connect

    2014-07-01

    In this project, Building America team IBACOS worked with a builder of single- and multifamily homes in southwestern Pennsylvania (climate zone 5) to understand its methods of successfully using polyethylene sheeting over aggregate as a capillary break beneath the slab in new construction. This builder’s homes vary in terms of whether they have crawlspaces or basements. However, in both cases, the strategy protects the home from water intrusion via capillary action (e.g., water wicking into cracks and spaces in the slab), thereby helping to preserve the durability of the home.

  6. Gold nanoparticle-modified etched capillaries for open-tubular capillary electrochromatography.

    PubMed

    Yang, Li; Guihen, Elizabeth; Holmes, Justin D; Loughran, Michael; O'sullivan, Gerard P; Glennon, Jeremy D

    2005-03-15

    The use of gold nanoparticles in conjunction with etched capillary-based open-tubular capillary electrochromatography (OTCEC) to improve the efficiency of separation and the selectivity between selected solutes is described. The fused-silica capillaries (50-microm i.d.) were etched with ammonium hydrogen difluoride, followed by prederivatization of the new surface with (3-mercaptopropyl)trimethoxysilane (MPTMS) for the immobilization of dodecanethiol gold nanoparticles, for OTCEC. The electrochromatography of a "reversed-phase" test mixture and of selected polycylic aromatic hydrocarbons was investigated, and efficient separations and high theoretical plate numbers per meter were obtained. The electroosmotic flow characteristics of the etched gold nanoparticle capillary, unetched gold nanoparticle capillary, bare capillary, and etched bare capillary were studied by varying the percentage of organic modifier in buffer, buffer pH, and separation voltage. Optical microscopy and scanning electron microscopy were used to examine the process of etching and modification and the surface features of the etched gold nanoparticle capillary. The results confirm that dodecanethiol gold nanoparticles bonded on the etched inner wall of the fused-silica capillary can provide sufficient solute-bonded phase interactions to obtain OTCEC separations with reproducible retention, as well as characteristic reversed-phase behavior, even with the inner diameter of the capillary of 50 microm. PMID:15762594

  7. Preparation of a sulfonated fused-silica capillary and its application in capillary electrophoresis and electrochromatography.

    PubMed

    Xu, Li; Feng, Yu-Qi; Shi, Zhi-Guo; Da, Shi-Lu; Wei, Fang

    2004-04-01

    In the present paper, two new methods, sol-gel and chemical bonding methods, were proposed for preparation of sulfonated fused-silica capillaries. In the sol-gel method, a fused-silica capillary was coated with the sol solution obtained by hydrolysis of 3-mercaptopropyltrimethoxysilane (MPTS) and tetramethoxysilane, and followed by age; while in the chemical bonding method, a capillary was chemically bonded directly with MPTS. Then, both the resulting capillaries were oxidized with an aqueous solution of hydrogen peroxide solution (H2O2) (30%, m/m) to obtain the sulfonated capillaries. The electroosmotic flow (EOF) for the sulfonated capillaries was found to remain almost constant within the studied pH range, and greater than that of the uncoated capillary. However, the coating efficiency of the capillary prepared by chemical bonding method was higher than that by sol-gel method, by comparing their magnitude of the EOF, the degree of disguise of the silanol and reproducibility of preparation procedure. The effects of the electrolyte's concentration and the content of methanol (MeOH) on the EOF were also studied. Especially, the study of the apparent pH (pH*) on the EOF in a water-MeOH system was reported. Finally, capillary electrophoretic separation of seven organic acids was achieved within 6.5 min under optimal condition using the chemically bonded sulfonated capillary. Moreover, separation of four alkaloids on the sulfonated capillary was compared with that on uncoated capillary in different conditions. Ion-exchange mechanism was found to play a key role for separation of these four basic analytes on the sulfonated capillary. PMID:15072301

  8. Towards new applications using capillary waveguides

    PubMed Central

    Stasio, Nicolino; Shibukawa, Atsushi; Papadopoulos, Ioannis N.; Farahi, Salma; Simandoux, Olivier; Huignard, Jean-Pierre; Bossy, Emmanuel; Moser, Christophe; Psaltis, Demetri

    2015-01-01

    In this paper we demonstrate the enhancement of the sensing capabilities of glass capillaries. We exploit their properties as optical and acoustic waveguides to transform them potentially into high resolution minimally invasive endoscopic devices. We show two possible applications of silica capillary waveguides demonstrating fluorescence and optical-resolution photoacoustic imaging using a single 330 μm-thick silica capillary. A nanosecond pulsed laser is focused and scanned in front of a capillary by digital phase conjugation through the silica annular ring of the capillary, used as an optical waveguide. We demonstrate optical-resolution photoacoustic images of a 30 μm-thick nylon thread using the water-filled core of the same capillary as an acoustic waveguide, resulting in a fully passive endoscopic device. Moreover, fluorescence images of 1.5 μm beads are obtained collecting the fluorescence signal through the optical waveguide. This kind of silica-capillary waveguide together with wavefront shaping techniques such as digital phase conjugation, paves the way to minimally invasive multi-modal endoscopy. PMID:26713182

  9. Towards new applications using capillary waveguides.

    PubMed

    Stasio, Nicolino; Shibukawa, Atsushi; Papadopoulos, Ioannis N; Farahi, Salma; Simandoux, Olivier; Huignard, Jean-Pierre; Bossy, Emmanuel; Moser, Christophe; Psaltis, Demetri

    2015-12-01

    In this paper we demonstrate the enhancement of the sensing capabilities of glass capillaries. We exploit their properties as optical and acoustic waveguides to transform them potentially into high resolution minimally invasive endoscopic devices. We show two possible applications of silica capillary waveguides demonstrating fluorescence and optical-resolution photoacoustic imaging using a single 330 μm-thick silica capillary. A nanosecond pulsed laser is focused and scanned in front of a capillary by digital phase conjugation through the silica annular ring of the capillary, used as an optical waveguide. We demonstrate optical-resolution photoacoustic images of a 30 μm-thick nylon thread using the water-filled core of the same capillary as an acoustic waveguide, resulting in a fully passive endoscopic device. Moreover, fluorescence images of 1.5 μm beads are obtained collecting the fluorescence signal through the optical waveguide. This kind of silica-capillary waveguide together with wavefront shaping techniques such as digital phase conjugation, paves the way to minimally invasive multi-modal endoscopy. PMID:26713182

  10. Fractal properties of capillary imbibition of rocks

    NASA Astrophysics Data System (ADS)

    Barabanov, V. L.; Lyubushin, A. A.

    2013-01-01

    In a series of laboratory experiments, the deterministic and fractal parameters of spontaneous capillary imbibition of rocks have been investigated. The capillary imbibition of higher-permeability samples was characterized by a sharp increase in the saturation at the initial stage and a further increase that is not described by the power law. Analysis of the parameters of the multifractal spectrum of water-saturation variations of the investigated samples in the process of capillary imbibition has shown that the generalized Hurst constant tends to decrease with time in the process of imbibition.

  11. Capillary force repels coffee-ring effect

    NASA Astrophysics Data System (ADS)

    Weon, Byung Mook; Je, Jung Ho

    2010-07-01

    When a coffee drop dries on a solid surface, it leaves a ringlike deposit along the edge and this is known as the coffee-ring effect. We find a different motion of particles repelling the coffee-ring effect in drying droplets; the motion of particles that is initially toward the edge by the coffee-ring effect is reversed toward the center by a capillary force. The reversal takes place when the capillary force prevails over the outward coffee-ring flow. We discuss the geometric constraints for the capillary force and the reverse motion. Our findings of reversal phenomena would be important in many scenarios of drying colloidal fluids.

  12. Arrested segregative phase separation in capillary tubes.

    PubMed

    Tromp, R Hans; Lindhoud, Saskia

    2006-09-01

    Phase separation in a capillary tube with one of the phases fully wetting the capillary wall is arrested when the typical size of the phase domains reaches the value of the diameter of the tube. The arrested state consists of an alternating sequence of concave-capped and convex-capped cylindrical domains, called "plugs," "bridges," or "lenses," of wetting and nonwetting phase, respectively. A description of this arrested plug state for an aqueous mixture of two polymer solutions is the subject of this work. A phase separating system consisting of two incompatible polymers dissolved in water was studied. The phase volume ratio was close to unity. The initial state from which plugs evolve is characterized by droplets of wetting phase in a continuous nonwetting phase. Experiments show the formation of plugs by a pathway that differs from the theoretically well-described instabilities in the thickness of a fluid thread inside a confined fluid cylinder. Plugs appear to form after the wetting layer (the confined fluid cylinder) has become unstable after merging of droplet with the wetting layer. The relative density of the phases could be set by the addition of salt, enabling density matching. As a consequence, the capillary length can in principle be made infinitely large and the Bond number (which represents the force of gravity relative to the capillary force) zero, without considerably changing the interfacial tension. Using the possibility of density matching, the relations among capillary length and capillary diameter on the one hand, and the presence of plugs and their average size on the other were studied. It was found that stable plugs are present when the capillary radius does not exceed a certain value, which is probably smaller than the capillary length. However, the average plug size is independent of capillary length. At constant capillary length, average plug size was found to scale with the capillary diameter to a power 1.3, significantly higher than the expected value of 1. Plug sizes had a polydispersity between 1.1 and 1.2 for all capillary radii for which this number could be reliably determined, suggesting a universal plug size distribution. Within plug sequences, size correlations were found between plugs with one to three plugs in between. This suggests the presence of an additional length scale. PMID:17025640

  13. Instability of capillary jets with thermocapillarity

    NASA Technical Reports Server (NTRS)

    Xu, J.-J.; Davis, S. H.

    1985-01-01

    Long axisymmetric liquid zones are subject to axial temperature gradients which induce steady viscous flows driven by thermocapillarity. The approximately parallel flow in a cylindrical zone is examined for linearized instabilities. Capillary, surface-wave and thermal modes are found. Capillary breakup can be retarded or even suppressed for small Prandtl number and large Biot number B, which measures heat transfer from the liquid to the surrounding atmosphere. In the limiting case B approaches infinity the zone becomes an isothermal jet subject to axial 'wind stress' on its interface. It is then possible to suppress capillary breakup entirely so that one can maintain long coherent jets.

  14. Micromechanism linear actuator with capillary force sealing

    DOEpatents

    Sniegowski, Jeffry J. (Albuquerque, NM)

    1997-01-01

    A class of micromachine linear actuators whose function is based on gas driven pistons in which capillary forces are used to seal the gas behind the piston. The capillary forces also increase the amount of force transmitted from the gas pressure to the piston. In a major subclass of such devices, the gas bubble is produced by thermal vaporization of a working fluid. Because of their dependence on capillary forces for sealing, such devices are only practical on the sub-mm size scale, but in that regime they produce very large force times distance (total work) values.

  15. Correlation between surface properties and wettability of multi-scale structured biocompatible surfaces

    NASA Astrophysics Data System (ADS)

    Gorodzha, S. N.; Surmeneva, M. A.; Prymak, O.; Wittmar, A.; Ulbricht, M.; Epple, M.; Teresov, A.; Koval, N.; Surmenev, R. A.

    2015-11-01

    The influence of surface properties of radio-frequency (RF) magnetron deposited hydroxyapatite (HA) and Si-containing HA coatings on wettability was studied. The composition and morphology of the coatings fabricated on titanium (Ti) were characterized using atomic force microscopy (AFM) and X-ray diffraction (XRD). The surface wettability was studied using contact angle analysis. Different geometric parameters of acid-etched (AE) and pulse electron beam (PEB)-treated Ti substrates and silicate content in the HA films resulted in the different morphology of the coatings at micro- and nano- length scales. Water contact angles for the HA coated Ti samples were evaluated as a combined effect of micro roughness of the substrate and nano-roughness of the HA films resulting in higher water contact angles compared with acid-etched (AE) or pulse electron beam (PEB) treated Ti substrates.

  16. Influences of ambient temperature, surface fluctuation and charge density on wettability properties of graphene film.

    PubMed

    Wang, Weidong; Zhang, Haiyan; Li, Shuai; Zhan, Yongjie

    2016-02-19

    Some molecular dynamics simulations focusing on the interactions between graphene films and water droplets are carried out in this article to investigate the fluid-solid interfacial behavior of surface wettability. The wettability of an ideal graphene film is investigated at room temperature at the beginning of the simulations, then the influences of ambient temperature, surface fluctuation and charge density of the graphene film on the wetting behaviors of water droplets on the film are also discussed from three points of view, namely the interaction energy of the graphene and the water droplet, the mass density of water and the water contact angle on the graphene film. The simulation results indicate that the ideal graphene film is slightly hydrophobic and that both the ambient temperature and the fluctuation of the graphene film play a negative role during the wetting processes. The observations also show that, once charged, the wetting property of graphene changes massively, from slightly hydrophobic to super-hydrophilic. PMID:26783182

  17. Influences of ambient temperature, surface fluctuation and charge density on wettability properties of graphene film

    NASA Astrophysics Data System (ADS)

    Wang, Weidong; Zhang, Haiyan; Li, Shuai; Zhan, Yongjie

    2016-02-01

    Some molecular dynamics simulations focusing on the interactions between graphene films and water droplets are carried out in this article to investigate the fluidsolid interfacial behavior of surface wettability. The wettability of an ideal graphene film is investigated at room temperature at the beginning of the simulations, then the influences of ambient temperature, surface fluctuation and charge density of the graphene film on the wetting behaviors of water droplets on the film are also discussed from three points of view, namely the interaction energy of the graphene and the water droplet, the mass density of water and the water contact angle on the graphene film. The simulation results indicate that the ideal graphene film is slightly hydrophobic and that both the ambient temperature and the fluctuation of the graphene film play a negative role during the wetting processes. The observations also show that, once charged, the wetting property of graphene changes massively, from slightly hydrophobic to super-hydrophilic.

  18. Influence of Substratum Wettability on Attachment of Freshwater Bacteria to Solid Surfaces

    PubMed Central

    Pringle, James H.; Fletcher, Madilyn

    1983-01-01

    We studied the attachment of a number of freshwater bacteria from River Sowe, Coventry, England, to test substrata. The attachment of each organism to hydrophobic and hydrophilic surfaces was evaluated, and further studies evaluated the attachment of selected isolates to a number of substrata with a range of water wettabilities. The wettability of each substratum was determined by contact angle measurements and was expressed as the work of adhesion (WA). No generic pattern of attachment to the test surfaces was found, although the majority of the organisms isolated showed a preference for the hydrophobic surface. A more detailed study of selected isolates showed a relationship between WA and number of attached cells. Each bacterium attached in maximum numbers to a surface that was characteristic of that organism and that had a WA between 75 and 105 mJ m?2. PMID:16346243

  19. Wettability Stabilizes Fluid Invasion into Porous Media via Nonlocal, Cooperative Pore Filling

    NASA Astrophysics Data System (ADS)

    Holtzman, Ran; Segre, Enrico

    2015-10-01

    We study the impact of the wetting properties on the immiscible displacement of a viscous fluid in disordered porous media. We present a novel pore-scale model that captures wettability and dynamic effects, including the spatiotemporal nonlocality associated with interface readjustments. Our simulations show that increasing the wettability of the invading fluid (the contact angle) promotes cooperative pore filling that stabilizes the invasion and that this effect is suppressed as the flow rate increases, due to viscous instabilities. We use scaling analysis to derive two dimensionless numbers that predict the mode of displacement. By elucidating the underlying mechanisms, we explain classical yet intriguing experimental observations. These insights could be used to improve technologies such as hydraulic fracturing, CO2 geosequestration, and microfluidics.

  20. A superhydrophobic to superhydrophilic in situ wettability switch of microstructured polypyrrole surfaces.

    PubMed

    Chang, Jean H; Hunter, Ian W

    2011-05-18

    We present an electrochemical layered system that allows for the fast, in situ wettability switch of microstructured PPy upon the application of an electric stimulus. We have eliminated the need for PPy to be immersed in an electrolyte to switch between wetting states, laying the groundwork for PPy to be used as a viable material in many applications, including microfluidics or smart textiles. The PPy surface was switched from the superhydrophobic state (contact angle=159) to the superhydrophilic state (contact angle=0) in 3 s. A wettability gradient was also created on a PPy surface using the layered system, causing a 3 µL droplet to travel approximately 2 mm in 0.8 s. PMID:21544891

  1. Tunable Surface Wettability of ZnO Nanoparticle Arrays for Controlling the Alignment of Liquid Crystals.

    PubMed

    Chung, Yueh-Feng; Chen, Mu-Zhe; Yang, Sheng-Hsiung; Jeng, Shie-Chang

    2015-05-13

    The control of the liquid crystal (LC) alignment is very important for both academic research and practical applications. LC molecules aligned on the ZnO nanoparticle arrays (ZnO NPAs) are demonstrated and the pretilt angles of LCs can be controlled by using ZnO NPAs with different surface wettability. The wettability of ZnO NPAs fabricated by the solution-based hydrothermal method can be controlled by changing the annealing temperature of the as-prepared ZnO NPAs. The measurements of the energy-dispersive spectra and photoluminescence have shown that the chemical properties of ZnO NPAs have been changed with the annealing temperature. Our results show that the pretilt angle of LCs can be tuned continuously from ?0 to ?90 as the contact angle of water on ZnO NPAs changes from 33 to 108. PMID:25895105

  2. Wettability Stabilizes Fluid Invasion into Porous Media via Nonlocal, Cooperative Pore Filling.

    PubMed

    Holtzman, Ran; Segre, Enrico

    2015-10-16

    We study the impact of the wetting properties on the immiscible displacement of a viscous fluid in disordered porous media. We present a novel pore-scale model that captures wettability and dynamic effects, including the spatiotemporal nonlocality associated with interface readjustments. Our simulations show that increasing the wettability of the invading fluid (the contact angle) promotes cooperative pore filling that stabilizes the invasion and that this effect is suppressed as the flow rate increases, due to viscous instabilities. We use scaling analysis to derive two dimensionless numbers that predict the mode of displacement. By elucidating the underlying mechanisms, we explain classical yet intriguing experimental observations. These insights could be used to improve technologies such as hydraulic fracturing, CO2 geosequestration, and microfluidics. PMID:26550879

  3. Structural, surface wettability and antibacterial properties of HPMC-ZnO nanocomposite

    NASA Astrophysics Data System (ADS)

    Rao, B. Lakshmeesha; Asha, S.; Madhukumar, R.; Latha, S.; Gowda, Mahadeva; Shetty, G. Rajesha; Chandra, K. Sharath; Naik, Prashantha; Sangappa

    2014-04-01

    The developed hydroxypropyl methylcellulose (HPMC)/Zinc oxide (ZnO) nanocomposite films were examined for structural property and surface wettability using X-ray diffraction and contact angle measurement. Antibacterial activity of these films was evaluated as a function of ZnO concentration. The microstructuralline parameters ( and (g in %)) decreased with increasing concentration of ZnO nanoparticles and there was increase in hydrophilicity. Addition of ZnO nanoparticles in films resulted in antimicrobial activity against tested microorganisms.

  4. Effect of Microstructural Evolution on Wettability of Laser Coated Calcium Phosphate on Titanium Alloy

    SciTech Connect

    Kurella, Anil K; Hu, Michael Z.; Dahotre, Narendra B

    2008-01-01

    Surface engineering of synthetic implant materials provides an exciting opportunity to mimic natural biomaterials. Surface that are bioactive and textured at multi scale have the potential for easier osseointegration. Ti alloy surfaces known for their biocompatibility are coated with bioactive Calcium Phosphate using a laser source at multiple processing speeds. The resulting surface has multiscale morphology and multi-phase chemical nature. Faster processing speeds showed improved wettability to water along with higher degree of crystallinity in the phases present.

  5. On the enhancement of probability of ion induced nucleation on partially wettable, water insoluble planar substrate

    NASA Astrophysics Data System (ADS)

    Singh, N.; Rai, J.; Varshneya, N. C.

    1990-06-01

    The nucleating behavior of partially wettable, water insoluble planar substrate has been studied. The rate and probability of nucleation were found to be enhanced in ion induced nucleation. It is found that there exists a threshold for angle of contact above which the effect of ions is dominant. The effect of ions is more pronounced at low supersaturation ratios and low temperatures for the material of large angle of contact w.r.t. water.

  6. Contact Lenses Wettability In Vitro: Effect of Surface-Active Ingredients

    PubMed Central

    Lin, Meng C.; Svitova, Tatyana F.

    2010-01-01

    Purpose To investigate the release of surface-active agents (surfactants) from unworn soft contact lenses and their influence on the lens surface wettability in vitro. Methods Surface tension (ST) of blister pack solutions was measured by pendant-drop technique. STs at the air-aqueous interface and contact angles (CAs) of four conventional and seven silicone hydrogel (SiH) soft contact lenses (SCLs) were evaluated in a dynamic-cycling regime using a modified captive-bubble tensiometer-goniometer. Measurements were performed immediately after removal from blister packs, and after soaking in a glass vial filled with a surfactant-free solution, which was replaced daily for one week. Lens surface wettability was expressed as adhesion energy (AE) according to Young’s equation. Results STs of all blister pack solutions were lower than the reference ST of pure water (72.5 mN/m), indicating the presence of surfactants. When lenses were depleted of surfactants by soaking, the STs of all studied lenses and advancing CAs of selected lenses increased (p < 0.001). Receding CAs of all studied lenses were 12° ± 5° and were not affected by the presence of surfactants. For most of the conventional lenses, the surface wettability was largely dependent on surfactants, and reduced significantly after surfactant depletion. In contrast, most SiH lenses exhibited stable and self-sustained surface wettability in vitro. Conclusions The manufacturer-added surfactants affected wetting properties of all studied SCLs, although to different degrees. PMID:20400924

  7. Metal oxide-based nanoparticles: revealing their potential to enhance oil recovery in different wettability systems

    NASA Astrophysics Data System (ADS)

    Hendraningrat, Luky; Torster, Ole

    2015-02-01

    This paper presents systematic studies of hydrophilic metal oxide nanoparticles (NPs) dispersed in brine intended to reveal their potential to enhance oil recovery (EOR) in various rock wettability systems. The stability in suspension (nanofluid) of the NPs has been identified as a key factor related to their use as an EOR agent. Experimental techniques have been developed for nanofluid stability using three coupled methods: direct visual observation, surface conductivity and particle size measurements. The use of a dispersant has been investigated and has been shown to successfully improve metal oxide nanofluid stability as a function of its concentration. The dispersant alters the nanofluid properties, i.e. surface conductivity, pH and particle size distribution. A two-phase coreflood experiment was conducted by injecting the stable nanofluids as a tertiary process (nano-EOR) through core plugs with various wettabilities ranging from water-wet to oil-wet. The combination of metal oxide nanofluid and dispersant improved the oil recovery to a greater extent than either silica-based nanofluid or dispersant alone in all wettability systems. The contact angle, interfacial tension (IFT) and effluent were also measured. It was observed that metal oxide-based nanofluids altered the quartz plates to become more water-wet, and the results are consistent with those of the coreflood experiment. The particle adsorption during the transport process was identified from effluent analysis. The presence of NPs and dispersant reduced the IFT, but its reduction is sufficient to yield significant additional oil recovery. Hence, wettability alteration plays a dominant role in the oil displacement mechanism using nano-EOR.

  8. Wettability of dentin after Yb:KYW thin-disk femtosecond ablation.

    PubMed

    Liu, Jing; L, Peijun; Sun, Yuchun; Wang, Yong

    2015-08-01

    The aim of this study was to quantitatively evaluate the wettability of dentin after Yb:KYW thin-disk femtosecond-pulsed laser ablation by measuring the contact angle. Different laser parameters were used including different fluences (F), scanning speeds, and scanning line spacings. Crowns of 15 extracted human teeth were cut longitudinally into slices approximately 1.5-mm thick with a cutting instrument. The samples were randomly divided into ten groups (n?=?3/group). Samples in groups 1-8 were irradiated with a femtosecond-pulsed laser. The dentin samples were fixed on a stage at the focal plane, and the laser beam irradiated the samples through a galvanometric scanning system so rectangular movement could be achieved. Samples in groups 9 and 10 were prepared with grinding instruments. Following ablation and preparation, the samples were examined for contact angle with an optical contact angle measuring instrument. The results showed that scanning speed and scanning line spacing had little influence on the wettability of dentin following femtosecond-pulsed laser ablation, except when F?=?6J/cm(2). For six out of the eight laser ablation groups, when a lower fluence was used, the dentin contact angle was higher and vice versa. Most of the dentin which had been ablated using the femtosecond-pulsed laser had improved wettability compared to samples prepared with the grinding instruments. This study showed that various laser fluences, scanning speeds, and scanning line spacings can alter dentin wettability. Therefore, adequate parameters should be chosen to achieve proper therapeutic benefits. PMID:25213830

  9. Surface roughness and wettability of enamel and dentine surfaces prepared with different dental burs.

    PubMed

    Al-Omari, W M; Mitchell, C A; Cunningham, J L

    2001-07-01

    The aim of dental adhesive restorations is to produce a long lasting union between the restoration and the tooth structure. This bond depends on many variables including the geometry of the preparation and the type of bonding agent or luting cement. It is therefore suggested that the topography of the tooth surface may influence the wettability and the bonding quality of adhesive systems. This study measured the surface roughness and wettability of enamel and dentine after preparation with different dental burs. The mesial and distal surfaces of 15 extracted sound human premolar teeth were prepared with a tungsten carbide crown bur, a diamond bur and a tungsten carbide finishing bur and finished in enamel or dentin, respectively. The prepared surfaces were analysed with a surface profilometer and scanning electron microscopy (SEM). The contact angle of distilled water on each of the prepared surfaces was used as the measure of wettability. The differences in average surface roughness (Ra) were significant between the rotary instrument groups, as revealed by a two-way ANOVA test. No differences were detected between enamel and dentine surfaces prepared with the same type of dental bur. The smoothest surfaces were those completed with tungsten carbide finishing burs. The diamond bur preparations were intermediate in the roughness assessment and the tungsten carbide crown burs gave the roughest surfaces. There were no significant differences in the contact angle measurements for the various groups. It was concluded that the surface roughness of enamel and dentine prepared by different rotary instruments had no significant influence on the wettability of distilled water on these surfaces. PMID:11422697

  10. WETTABILITY AND PREDICTION OF OIL RECOVERY FROM RESERVOIRS DEVELOPED WITH MODERN DRILLING AND COMPLETION FLUIDS

    SciTech Connect

    Jill S. Buckley; Norman R. Morrow

    2005-04-01

    Exposure to crude oil in the presence of an initial brine saturation can render rocks mixed-wet. Subsequent exposure to components of synthetic oil-based drilling fluids can alter the wetting toward less water-wet or more oil-wet conditions. Mixing of the non-aromatic base oils used in synthetic oil-based muds (SBM) with an asphaltic crude oil can destabilize asphaltenes and make cores less water-wet. Wetting changes can also occur due to contact with the surfactants used in SBM formulations to emulsify water and make the rock cuttings oil-wet. Reservoir cores drilled with SBMs, therefore, show wetting properties much different from the reservoir wetting conditions, invalidating laboratory core analysis using SBM contaminated cores. Core cleaning is required in order to remove all the drilling mud contaminants. In theory, core wettability can then be restored to reservoir wetting conditions by exposure to brine and crude oil. The efficiency of core cleaning of SBM contaminated cores has been explored in this study. A new core cleaning procedure was developed aimed to remove the adsorbed asphaltenes and emulsifiers from the contaminated Berea sandstone cores. Sodium hydroxide was introduced into the cleaning process in order to create a strongly alkaline condition. The high pH environment in the pore spaces changed the electrical charges of both basic and acidic functional groups, reducing the attractive interactions between adsorbing materials and the rock surface. In cores, flow-through and extraction methods were investigated. The effectiveness of the cleaning procedure was assessed by spontaneous imbibition tests and Amott wettability measurements. Test results indicating that introduction of sodium hydroxide played a key role in removing adsorbed materials were confirmed by contact angle measurements on similarly treated mica surfaces. Cleaning of the contaminated cores reversed their wettability from oil-wet to strongly water-wet as demonstrated by spontaneous imbibition rates and Amott wettability indices.

  11. Structural, surface wettability and antibacterial properties of HPMC-ZnO nanocomposite

    SciTech Connect

    Rao, B. Lakshmeesha; Asha, S.; Madhukumar, R.; Latha, S.; Gowda, Mahadeva; Shetty, G. Rajesha; Sangappa; Chandra, K. Sharath; Naik, Prashantha

    2014-04-24

    The developed hydroxypropyl methylcellulose (HPMC)/Zinc oxide (ZnO) nanocomposite films were examined for structural property and surface wettability using X-ray diffraction and contact angle measurement. Antibacterial activity of these films was evaluated as a function of ZnO concentration. The microstructuralline parameters ( and (g in %)) decreased with increasing concentration of ZnO nanoparticles and there was increase in hydrophilicity. Addition of ZnO nanoparticles in films resulted in antimicrobial activity against tested microorganisms.

  12. Contact angles and wettability of ionic liquids on polar and non-polar surfaces.

    PubMed

    Pereira, Matheus M; Kurnia, Kiki A; Sousa, Filipa L; Silva, Nuno J O; Lopes-da-Silva, Jos A; Coutinho, Joo A P; Freire, Mara G

    2015-11-25

    Many applications involving ionic liquids (ILs) require the knowledge of their interfacial behaviour, such as wettability and adhesion. In this context, herein, two approaches were combined aiming at understanding the impact of the IL chemical structures on their wettability on both polar and non-polar surfaces, namely: (i) the experimental determination of the contact angles of a broad range of ILs (covering a wide number of anions of variable polarity, cations, and cation alkyl side chain lengths) on polar and non-polar solid substrates (glass, Al-plate, and poly-(tetrafluoroethylene) (PTFE)); and (ii) the correlation of the experimental contact angles with the cation-anion pair interaction energies generated by the Conductor-like Screening Model for Real Solvents (COSMO-RS). The combined results reveal that the hydrogen-bond basicity of ILs, and thus the IL anion, plays a major role through their wettability on both polar and non-polar surfaces. The increase of the IL hydrogen-bond accepting ability leads to an improved wettability of more polar surfaces (lower contact angles) while the opposite trend is observed on non-polar surfaces. The cation nature and alkyl side chain lengths have however a smaller impact on the wetting ability of ILs. Linear correlations were found between the experimental contact angles and the cation-anion hydrogen-bonding and cation ring energies, estimated using COSMO-RS, suggesting that these features primarily control the wetting ability of ILs. Furthermore, two-descriptor correlations are proposed here to predict the contact angles of a wide variety of ILs on glass, Al-plate, and PTFE surfaces. A new extended list is provided for the contact angles of ILs on three surfaces, which can be used as a priori information to choose appropriate ILs before a given application. PMID:26554705

  13. New concept for coal wettability evaluation and modulation. Technical progress report, April 1--June 30, 1995

    SciTech Connect

    Hu, W.

    1996-05-01

    The objective of this project is to evaluate the surface wettability and flotation of coal and pyrite in order to establish a new separation strategy for advanced coal cleaning for premium fuel applications. During this quarter, mini-cell flotation tests were carried out on Upper Freeport, Pittsburgh No. 8, and Illinois No. 6 coals, and two pyrite samples. Flotation media used were kerosene, benzene, and amyl-xanthate. Test results are given and discussed.

  14. Improving the wettability of 2024 aluminium alloy by means of cold plasma treatment

    NASA Astrophysics Data System (ADS)

    Polini, W.; Sorrentino, L.

    2003-05-01

    Aluminium alloys are heavily used to manufacture structural parts in the aeronautic industry because of its lightness and its corrosion resistance. These alloys are successfully used in other industrial fields too, such as railway, automotive and naval industries. The need to contrast the severe use conditions and the heavy stresses developing in aeronautic field implies to protect the surfaces of the structures in aluminium alloy by any deterioration. To preserve by deterioration, it is necessary to make aluminium more suitable to be coated by protective paint. In the aeronautic industry, a complex and critical process is used in order to enhance both wettability and adhesive properties of aluminium alloy surfaces. Cold plasma treatment represents an efficient, clean and economic alternative to activate aluminium surfaces. The present work deals with air cold plasma treatment of 2024 aluminium alloy surfaces. The influence of dc electrical discharge cold plasma parameters on wettability of 2024 aluminium alloy surfaces has been studied. A set of process variables (voltage, time and air flow rate) has been identified and used to conduct some experimental tests on the basis of design of experiment (DOE) techniques. The experimental results show that the proposed plasma process may considerably increase aluminium alloy wettability. These results represent the first step in trying to optimise the aluminium adhesion by means of this non-conventional manufacturing process.

  15. A Review on the Wettability of Dental Implant Surfaces II: Biological and Clinical Aspects

    PubMed Central

    Gittens, Rolando A.; Scheideler, Lutz; Rupp, Frank; Hyzy, Sharon L.; Geis-Gerstorfer, Jürgen; Schwartz, Zvi; Boyan, Barbara D.

    2014-01-01

    Dental and orthopaedic implants have been under continuous advancement to improve their interactions with bone and ensure a successful outcome for patients. Surface characteristics such as surface topography and surface chemistry can serve as design tools to enhance the biological response around the implant, with in vitro, in vivo and clinical studies confirming their effects. However, the comprehensive design of implants to promote early and long-term osseointegration requires a better understanding of the role of surface wettability and the mechanisms by which it affects the surrounding biological environment. This review provides a general overview of the available information about the contact angle values of experimental and of marketed implant surfaces, some of the techniques used to modify surface wettability of implants, and results from in vitro and clinical studies. We aim to expand the current understanding on the role of wettability of metallic implants at their interface with blood and the biological milieu, as well as with bacteria, and hard and soft tissues. PMID:24709541

  16. Controlling wettability and hydrophobicity of organoclays modified with quaternary ammonium surfactants.

    PubMed

    Shah, Kinjal J; Mishra, Manish Kumar; Shukla, Atindra D; Imae, Toyoko; Shah, Dinesh O

    2013-10-01

    The montmorillonite clays were modified with quaternary ammonium salts (QASs) having different alkyl chain lengths and a benzyl substitute group. The modified organoclays were characterized by different analytical techniques. The wettability and hydrophilicity/hydrophobicity of the modified clays was evaluated using water or oil penetration (adsorption) and contact angle measurements. The loading of QASs was in the range of 0.60-0.75 mmol/g per clay, irrespective of the type of QAS used for the modification of the clay. From the analytical investigations, it was elucidated that the modification of clay with QAS affected the structural, textural, and surface properties. Moreover, it should be noted that the modification with QAS having benzyl substitute group resulted in water-non-wettable and superhydrophobic surface, whereas clays modified with QAS without benzyl substitute group became more water-wettable and hydrophilic than the pristine clay. The presence of benzyl groups on the clay prevents water from penetration into the inter-clay or interlayer spacing, which yields the hydrophobic surface. These behaviors can arise from molecular arrangement of QAS on clay but not be attributable to the amount of QASs, and the surface area, size, and zeta potential of particles. PMID:23830282

  17. Interfacial dynamics of two immiscible fluids in spatially periodic porous media: The role of substrate wettability

    NASA Astrophysics Data System (ADS)

    Mondal, Pranab Kumar; DasGupta, Debabrata; Chakraborty, Suman

    2014-07-01

    We delineate the contact line dynamics of two immiscible fluids in a medium having spatially periodic porous structures. The flow is driven by an external applied pressure gradient. We bring out the combined consequences of the solid fraction distribution and the substrate wettability on the resulting dynamics of the contact line, by employing phase-field formalism. We capture the sequence of spatiotemporal events leading to formation of liquid bridges by trapping a small amount of displaced phase fluid between two consecutive porous blocks, as dictated by the combinations of substrate wettability and solid fraction. We also demonstrate the existence of a regime of complete interfacial recovery, depending on the parametric space of the governing parameters under concern. Our results essentially demonstrate the intricate mechanisms by virtue of which the wettabilities of the substrates alter the dynamical evolutions of interfaces and the subsequent shapes and sizes of the adsorbed dispersed phases, bearing far-ranging consequences in several practical applications ranging from oil recovery to groundwater flow.

  18. Mussel (Mytilus edulis) byssus deposition in response to variations in surface wettability

    PubMed Central

    Aldred, N; Ista, L.K; Callow, M.E; Callow, J.A; Lopez, G.P; Clare, A.S

    2005-01-01

    Mussels (Mytilus edulis) are economically important in their role as an aquaculture species and also with regard to marine biofouling. They attach tenaciously to a wide variety of submerged surfaces by virtue of collagenous attachment threads termed byssi. The aim of this study was to characterize the spreading of the byssal attachment plaque, which mediates attachment to the surface, on a range of surfaces in response to changes in wettability. To achieve this, well characterized self-assembled monolayers of ?-terminated alkanethiolates on gold were used, allowing correlation of byssal plaque spreading with a single surface characteristicwettability. The present results were inconsistent with those from previous studies, in that there was a positive correlation between plaque size and surface wettability; a trend which is not explained by conventional wetting theory for a three-phase system. A recent extension to wetting theory with regard to hydrophilic proteins is discussed and the results of settlement assays are used to attempt reconciliation of these results with those of similar previous studies and, also, with recent data presented for the spreading of Ulva linza spore adhesive. PMID:16849215

  19. Supercritical CO2 and Ionic Strength Effects on Wettability of Silica Surfaces: Equilibrium Contact Angle Measurements

    SciTech Connect

    Jung, J. W.; Wan, Jiamin

    2012-09-20

    Wettability of reservoir mineral surfaces is a critical factor controlling CO{sub 2} mobility, trapping, and safe-storage in geological carbon sequestration. Although recent studies have begun to show that wettability of some minerals can change in the presence of supercritical CO{sub 2} (scCO{sub 2}), different laboratories have reported significantly different wetting behavior. We studied wettability alteration of silica in CO{sub 2}brine systems through measuring equilibrium water contact angles under wide ranges of pressures (0.1 to 25 MPa) and ionic strengths (0 to 5.0 M NaCl), at 45 C. Using two independent approaches for each of the experiments, we found the following: (1) Equilibrium water contact angles on silica increased up to 17.6 2.0 as a result of reactions with scCO{sub 2}. This increase occurred primarily within the pressure range 710 MPa, and the contact angles remain nearly constant at pressure greater than 10 MPa. (2) The contact angle increased with ionic strength nearly linearly, with a net increase of 19.6 2.1 at 5.0 M NaCl. These changes in contact angle induced by changes in scCO{sub 2} pressure and aqueous solution ionic strength are approximately additive over the range of tested conditions. These findings can be used to estimate the wetting behavior of silica surfaces in reservoirs containing supercritical CO{sub 2}.

  20. Morphing and vectoring impacting droplets by means of wettability-engineered surfaces

    PubMed Central

    Schutzius, Thomas M.; Graeber, Gustav; Elsharkawy, Mohamed; Oreluk, James; Megaridis, Constantine M.

    2014-01-01

    Driven by its importance in nature and technology, droplet impact on solid surfaces has been studied for decades. To date, research on control of droplet impact outcome has focused on optimizing pre-impact parameters, e.g., droplet size and velocity. Here we follow a different, post-impact, surface engineering approach yielding controlled vectoring and morphing of droplets during and after impact. Surfaces with patterned domains of extreme wettability (high or low) are fabricated and implemented for controlling the impact process during and even after rebound a previously neglected aspect of impact studies on non-wetting surfaces. For non-rebound cases, droplets can be morphed from spheres to complex shapes without unwanted loss of liquid. The procedure relies on competition between surface tension and fluid inertial forces, and harnesses the naturally occurring contact-line pinning mechanisms at sharp wettability changes to create viable dry regions in the spread liquid volume. Utilizing the same forces central to morphing, we demonstrate the ability to rebound orthogonally-impacting droplets with an additional non-orthogonal velocity component. We theoretically analyze this capability and derive a We?.25 dependence of the lateral restitution coefficient. This study offers wettability-engineered surfaces as a new approach to manipulate impacting droplet microvolumes, with ramifications for surface microfluidics and fluid-assisted templating applications. PMID:25392084

  1. Switchable Wettability of the Honeybee’s Tongue Surface Regulated by Erectable Glossal Hairs

    PubMed Central

    Chen, Ji; Wu, Jianing; Yan, Shaoze

    2015-01-01

    Various nectarivorous animals apply bushy-hair-equipped tongues to lap nectar from nectaries of flowers. A typical example is provided by the Italian honeybee (Apis mellifera ligustica), who protracts and retracts its tongue (glossa) through a temporary tube, and actively controls the erectable glossal hairs to load nectar. We first examined the microstructure of the honeybee’s glossal surface, recorded the kinematics of its glossal hairs during nectar feeding process and observed the rhythmical hair erection pattern clearly. Then we measured the wettability of the glossal surface under different erection angles (EA) in sugar water of the mass concentration from 25 to 45%, mimicked by elongating the glossa specimens. The results show that the EA in retraction approximately remains stable under different nectar concentrations. In a specific concentration (35, 45, or 55%), the contact angle decreases and glossal surface area increases while the EA of glossal hairs rises, the glossa therefore could dynamically alter the glossal surface and wettability in foraging activities, not only reducing the energy consumption for impelling the nectar during tongue protraction, but also improving the nectar-trapping volume for feeding during glossa retraction. The dynamic glossal surface with switchable wettability regulated by erectable hairs may reveal the effective adaptation of the honeybee to nectar intake activities. PMID:26643560

  2. Tuning the surface wettability of carbon nanotube carpets in multiscale hierarchical solids

    NASA Astrophysics Data System (ADS)

    Karumuri, Anil K.; He, Lvmeng; Mukhopadhyay, Sharmila M.

    2015-02-01

    An attractive approach of increasing functionality of solid surfaces is to create hierarchical multiscale morphology by attaching tailored carpet-like arrays of Carbon nanotubes (CNT) on them. Such surfaces offer fractal morphology along with unprecedented increase in specific surface areas, and significantly boost the potency of porous materials used in surface-active applications. However, full utilization of these structures will require intimate interaction between the solid surface and its environmental fluid. CNT arrays tend to be hydrophobic, which limit their effectiveness in aqueous environments. In this research, we investigated two different surface modifications methods to induce hydrophilic property to CNT nano-carpets on graphitic substrates: dry oxygen plasma treatment and wet sol-gel oxide coating. Structure, morphology, composition and chemistry of these multiscale surfaces have been related to wettability and water flow properties. Plasma oxygen treatments did not alter the surface morphology, but induced temporary wettability, that could be reversed by heat treatment. On the other hand, sol-gel treatment permanently coated the nanotubes with a strongly bonded layer of amorphous SiO2. This coating imparts permanent alterations in surface chemistry, contact angle, wettability and water flow. Porous carbon foams were coated with CNT arrays and their water permeability measured before and after sol-gel silica coating. The hydrophilic coating was seen to increase flow rate and reduce pressure build-up. These results have important implications on all devices that utilize surface activity of porous solids, such as catalytic membranes, antimicrobial filters, and microfluidic sensors.

  3. Wettability of brazing alloys on molybdenum and TZM (Mo-Ti-Zr alloy)

    SciTech Connect

    McDonald, M.M.; Keller, D.L.; Heiple, C.R.; Hofmann, W.E.

    1988-01-01

    Vacuum brazing studies have been performed on molybdenum and TZM (0.5Ti-0.08Zr-Mo). Wettability tests have been conducted for nineteen braze metal filler alloys on molybdenum and thirty-two braze metal filler alloys on TZM over a wide range of temperatures. A wetting index, which is a function of contact angle and braze alloy contact area, was determined for each filler alloy at each brazing temperature. The nature and extent of interaction between the brazing alloys and the base metals was analyzed by conventional metallography, scanning-electron microscopy, and electron microprobe analysis. A comparison is made between the behavior of filler alloys on molybdenum and TZM -- filler alloys consistently exhibited less wettability on TZM than on molybdenum. The lower wettability of TZM is believed to be due to a small amount of titanium in the surface oxide on TZM. Cracking was observed in the base metal under some of the high temperature braze deposits. The cracking is shown to arise from liquid metal embrittlement from nickel in the high temperature braze alloys. 7 refs., 11 figs., 2 tabs.

  4. Wettability and Coalescence of Cu Droplets Subjected to Two-Wall Confinement

    PubMed Central

    Li, Xiongying; Ren, Hongru; Wu, Weikang; Li, Hui; Wang, Long; He, Yezeng; Wang, Junjun; Zhou, Yi

    2015-01-01

    Controlling droplet dynamics via wettability or movement at the nanoscale is a significant goal of nanotechnology. By performing molecular dynamics simulations, we study the wettability and spontaneous coalescence of Cu droplets confined in two carbon walls. We first focus on one drop in the two-wall confinement to reveal confinement effects on wettability and detaching behavior of metallic droplets. Results show that Cu droplets finally display three states: non-detachment, semi-detachment and full detachment, depending on the height of confined space. The contact angle ranges from 125° to 177°, and the contact area radius ranges from 12 to ~80 Å. The moving time of the detached droplet in the full detachment state shows a linear relationship with the height of confined space. Further investigations into two drops subjected to confinement show that the droplets, initially distant from each other, spontaneously coalesce into a larger droplet by detachment. The coalescing time and final position of the merged droplet are precisely controlled by tailoring surface structures of the carbon walls, the height of the confined space or a combination of these approaches. These findings could provide an effective method to control the droplet dynamics by confinement. PMID:26459952

  5. Switchable Wettability of the Honeybee's Tongue Surface Regulated by Erectable Glossal Hairs.

    PubMed

    Chen, Ji; Wu, Jianing; Yan, Shaoze

    2015-01-01

    Various nectarivorous animals apply bushy-hair-equipped tongues to lap nectar from nectaries of flowers. A typical example is provided by the Italian honeybee (Apis mellifera ligustica), who protracts and retracts its tongue (glossa) through a temporary tube, and actively controls the erectable glossal hairs to load nectar. We first examined the microstructure of the honeybee's glossal surface, recorded the kinematics of its glossal hairs during nectar feeding process and observed the rhythmical hair erection pattern clearly. Then we measured the wettability of the glossal surface under different erection angles (EA) in sugar water of the mass concentration from 25 to 45%, mimicked by elongating the glossa specimens. The results show that the EA in retraction approximately remains stable under different nectar concentrations. In a specific concentration (35, 45, or 55%), the contact angle decreases and glossal surface area increases while the EA of glossal hairs rises, the glossa therefore could dynamically alter the glossal surface and wettability in foraging activities, not only reducing the energy consumption for impelling the nectar during tongue protraction, but also improving the nectar-trapping volume for feeding during glossa retraction. The dynamic glossal surface with switchable wettability regulated by erectable hairs may reveal the effective adaptation of the honeybee to nectar intake activities. PMID:26643560

  6. Improved wettability of an experimental silicone rubber denture soft lining material.

    PubMed

    Waters, M; Jagger, R

    1999-01-01

    The purpose of this study was to improve the wettability of an experimental silicone rubber soft lining material (Sildent) to increase patient comfort. Sildent was modified by the addition of polyalkylene oxide poly(dimethylsiloxane) surfactants. The various surfactants were added directly to the polymeric matrix in the quantities 5, 10, 20% w/w. The surfactants were also added to a one part silicone sealant, which was then painted onto the surface of already cured Sildent. Contact angle measurements were made on samples using a dynamic contact angle analyzer. Results showed that incorporation of surfactants A (Silwet L7600) and B (Silwet L7607) effectively improved the wettability of Sildent. This improvement was still evident after 6 months storage in distilled water at 37 degrees C suggesting retention of the surfactants matrix via physio-chemical bonding. Formulations with surfactants added directly to the matrix showed unacceptable water absorption after 2 months in distilled water. Samples with surfactant charged sealant painted on the surface showed a lower water absorption. In conclusion, Sildent formulations modified with polyalkylene silicone surfactants showed improved wettability compared to unmodified Sildent. Further work is needed to reduce water uptake and determine the effect on key mechanical properties. PMID:10556838

  7. Wettability and Coalescence of Cu Droplets Subjected to Two-Wall Confinement

    NASA Astrophysics Data System (ADS)

    Li, Xiongying; Ren, Hongru; Wu, Weikang; Li, Hui; Wang, Long; He, Yezeng; Wang, Junjun; Zhou, Yi

    2015-10-01

    Controlling droplet dynamics via wettability or movement at the nanoscale is a significant goal of nanotechnology. By performing molecular dynamics simulations, we study the wettability and spontaneous coalescence of Cu droplets confined in two carbon walls. We first focus on one drop in the two-wall confinement to reveal confinement effects on wettability and detaching behavior of metallic droplets. Results show that Cu droplets finally display three states: non-detachment, semi-detachment and full detachment, depending on the height of confined space. The contact angle ranges from 125 to 177, and the contact area radius ranges from 12 to ~80?. The moving time of the detached droplet in the full detachment state shows a linear relationship with the height of confined space. Further investigations into two drops subjected to confinement show that the droplets, initially distant from each other, spontaneously coalesce into a larger droplet by detachment. The coalescing time and final position of the merged droplet are precisely controlled by tailoring surface structures of the carbon walls, the height of the confined space or a combination of these approaches. These findings could provide an effective method to control the droplet dynamics by confinement.

  8. Laser surface modification of AZ31B Mg alloy for bio-wettability.

    PubMed

    Ho, Yee-Hsien; Vora, Hitesh D; Dahotre, Narendra B

    2015-02-01

    Magnesium alloys are the potential degradable materials for load-bearing implant application due to their comparable mechanical properties to human bone, excellent bioactivity, and in vivo non-toxicity. However, for a successful load-bearing implant, the surface of bio-implant must allow protein absorption and layer formation under physiological environment that can assist the cell/osteoblast growth. In this regard, surface wettability of bio-implant plays a key role to dictate the quantity of protein absorption. In light of this, the main objective of the present study was to produce favorable bio-wettability condition of AZ31B Mg alloy bio-implant surface via laser surface modification technique under various laser processing conditions. In the present efforts, the influence of laser surface modification on AZ31B Mg alloy surface on resultant bio-wettability was investigated via contact-angle measurements and the co-relationships among microstructure (grain size), surface roughness, surface energy, and surface chemical composition were established. In addition, the laser surface modification technique was simulated by computational (thermal) model to facilitate the prediction of temperature and its resultant cooling/solidification rates under various laser processing conditions for correlating with their corresponding composition and phase evolution. These predicted thermal properties were later used to correlate with the corresponding microstructure, chemical composition, and phase evolution via experimental analyses (X-ray diffractometer, scanning electron microscope, energy-dispersive spectroscopy). PMID:25201909

  9. Thermal singularity and contact line motion in pool boiling: Effects of substrate wettability

    NASA Astrophysics Data System (ADS)

    Taylor, M. T.; Qian, Tiezheng

    2016-03-01

    The dynamic van der Waals theory [Phys. Rev. E 75, 036304 (2007), 10.1103/PhysRevE.75.036304] is employed to model the growth of a single vapor bubble in a superheated liquid on a flat homogeneous substrate. The bubble spreading dynamics in the pool boiling regime has been numerically investigated for one-component van der Waals fluids close to the critical point, with a focus on the effect of the substrate wettability on bubble growth and contact line motion. The substrate wettability is found to control the apparent contact angle and the rate of bubble growth (the rate of total evaporation), through which the contact line speed is determined. An approximate expression is derived for the contact line speed, showing good agreement with the simulation results. This demonstrates that the contact line speed is primarily governed by (1) the circular shape of interface (for slow bubble growth), (2) the constant apparent contact angle, and (3) the constant bubble growth rate. It follows that the contact line speed has a sensitive dependence on the substrate wettability via the apparent contact angle which also determines the bubble growth rate. Compared to hydrophilic surfaces, hydrophobic surfaces give rise to a thinner shape of bubble and a higher rate of total evaporation, which combine to result in a much faster contact line speed. This can be linked to the earlier formation of a vapor film and hence the onset of boiling crisis.

  10. Amino acid conjugated self assembling molecules for enhancing surface wettability of fiber laser treated titanium surfaces

    NASA Astrophysics Data System (ADS)

    Akkan, Cagri K.; Hür, Deniz; Uzun, Lokman; Garipcan, Bora

    2016-03-01

    Surface wetting properties of implants are one of the most critical parameter, which determine the interaction of proteins and cells with the implant surface. In this regards, acid etching and sand blasting are the mostly used methods at surface modification of Titanium (Ti) for enhanced surface wettability. Besides, these kinds of modifications may cause a conflict whether the surface wettability is influenced by the process related surface contaminations or by the surface roughness. In contrast, lasers might be an option for the alteration of surface wetting properties via supporting micro and/or nano surface topographies while preventing surface chemical contaminations. In this work, we focused on two steps of surface processing approaches of Ti surface: physical and chemical modifications. Herein, we hierarchically structured Ti surfaces by using microsecond modulated pulsed fiber laser. Subsequently, laser structured and non-structured Ti surfaces were further modified with novel histidine and leucine Amino Acid conjugated Self-Assembled Molecules (His1-SAMs2 and Leu3-SAMs) to alter the surface wettability by introducing biologically hydrophilic and hydrophobic groups. Modification of Ti surfaces with His-SAMs and Leu-SAMs ended up with stable wetting properties when compared to non-modified surfaces after 7 days which may enhances the cell-surface interaction.

  11. Water-wettable polypropylene fibers by facile surface treatment based on soy proteins.

    PubMed

    Salas, Carlos; Genzer, Jan; Lucia, Lucian A; Hubbe, Martin A; Rojas, Orlando J

    2013-07-24

    Modification of the wetting behavior of hydrophobic surfaces is essential in a variety of materials, including textiles and membranes that require control of fluid interactions, adhesion, transport processes, sensing, etc. This investigation examines the enhancement of wettability of an important class of textile materials, viz., polypropylene (PP) fibers, by surface adsorption of different proteins from soybeans, including soy flour, isolate,glycinin, and ?-conglycinin. Detailed investigations of soy adsorption from aqueous solution (pH 7.4, 25 C) on polypropylene thin films is carried out using quartz crystal microbalance (QCM) and surface plasmon resonance (SPR). A significant amount of protein adsorbs onto the PP surfaces primarily due to hydrophobic interactions. We establish that adsorption of a cationic surfactant, dioctadecyldimethylammonium bromide (DODA) onto PP surfaces prior to the protein deposition dramatically enhances its adsorption. The adsorption of proteins from native (PBS buffer, pH 7.4, 25 C) and denatured conditions (PBS buffer, pH 7.4, 95 C) onto DODA-treated PP leads to a high coverage of the proteins on the PP surface as confirmed by a significant improvement in water wettability. A shift in the contact angle from 128 to completely wettable surfaces (?0) is observed and confirmed by imaging experiments conducted with fluorescence tags. Furthermore, the results from wicking tests indicate that hydrophobic PP nonwovens absorb a significant amount of water after protein treatment, i.e., the PP-modified surfaces become completely hydrophilic. PMID:23789986

  12. Influence of surface topography and surface physicochemistry on wettability of zirconia (tetragonal zirconia polycrystal).

    PubMed

    Noro, Akio; Kaneko, Morio; Murata, Isao; Yoshinari, Masao

    2013-02-01

    Surface modification technologies are available for tetragonal zirconia polycrystal (TZP) to enhance its bioactivity and osseointegration capability. The surface wettability of an implant material is one of the important factors in the process of osseointegration, possibly regulating protein adsorption, and subsequent cell behavior. The aim of this study was to clarify the effect of topographical or physicochemical modification of TZP ceramics on wettability to determine the potential of such treatment in application to implants. Several types of surface topography were produced by alumina blasting and acid etching with hydrofluoric acid; surface physicochemistry was modified with oxygen (O(2)) plasma, ultraviolet (UV) light, or hydrogen peroxide treatment. The obtained specimens were also subjected to storage under various conditions to evaluate their potential to maintain superhydrophilicity. The results showed that surface modification of surface topography or physicochemistry, especially of blast/acid etching as well as O(2) plasma and UV treatment, greatly increased the surface wettability, resulting in superhydrophilicity. X-ray photoelectron spectroscopy revealed that a remarkable decrease in carbon content and the introduction of hydroxyl groups were responsible for the observed superhydrophilicity. Furthermore, superhydrophilicity was maintained, even after immersion in an aqueous solution, an important consideration in the clinical application of this technology. PMID:23165774

  13. Surface energy engineering for tunable wettability through controlled synthesis of MoS2.

    PubMed

    Gaur, Anand P S; Sahoo, Satyaprakash; Ahmadi, Majid; Dash, Saroj P; Guinel, Maxime J-F; Katiyar, Ram S

    2014-08-13

    MoS2 is an important member of the transition metal dichalcogenides that is emerging as a potential 2D atomically thin layered material for low power electronic and optoelectronic applications. However, for MoS2 a critical fundamental question of significant importance is how the surface energy and hence the wettability is altered at the nanoscale in particular, the role of crystallinity and orientation. This work reports on the synthesis of large area MoS2 thin films on insulating substrates (SiO2/Si and Al2O3) with different surface morphology via vapor phase deposition by varying the growth temperatures. The samples were examined using transmission electron microscopy and Raman spectroscopy. From contact angle measurements, it is possible to correlate the wettability with crystallinity at the nanoscale. The specific surface energy for few layers MoS2 is estimated to be about 46.5 mJ/m(2). Moreover a layer thickness-dependent wettability study suggests that the lower the thickness is, the higher the contact angle will be. Our results shed light on the MoS2-water interaction that is important for the development of devices based on MoS2 coated surfaces for microfluidic applications. PMID:25073904

  14. Experiments on the Motion of Drops on a Horizontal Solid Surface due to a Wettability Gradient

    NASA Technical Reports Server (NTRS)

    Moumen, Nadjoua; Subramanian, R, Shankar; MLaughlin, john B.

    2006-01-01

    Results from experiments performed on the motion of drops of tetraethylene glycol in a wettability gradient present on a silicon surface are reported and compared with predictions from a recently developed theoretical model. The gradient in wettability was formed by exposing strips cut from a silicon wafer to decyltrichlorosiland vapors. Video images of the drops captured during the experiments were subsequently analyzed for drop size and velocity as functions of position along the gradient. In separate experiments on the same strips, the static contact angle formed by small drops was measured and used to obtain the local wettability gradient to which a drop is subjected. The velocity of the drops was found to be a strong function of position along the gradient. A quasi-steady theoretical model that balances the local hydrodynamic resistance with the local driving force generally describes the observations; possible reasons for the remaining discrepancies are discussed. It is shown that a model in which the driving force is reduced to accomodate the hysteresis effect inferred from the data is able to remove most of the discrepancy between the observed and predicted velocities.

  15. WETTABILITY ALTERATION OF CARBONATE ROCK MEDIATED BY BIOSURFACTANT PRODUCED FROM HIGH-STARCH AGRICULTURAL EFFLUENTS

    SciTech Connect

    Mehdi Salehi; Stephen Johnson; Gregory Bala; Jenn-Tai Liang

    2006-09-01

    Surfactants can be used to alter wettability of reservoir rock, increasing spontaneous imbibition and thus improving oil yields. Commercial synthetic surfactants are often prohibitively expensive and so a crude preparation of the anionic biosurfactant, surfactin, from Bacillus subtilis grown on high-starch industrial and agricultural effluents has been proposed as an economical alternative. To assess the effectiveness of the surfactin, it is compared to commercially available surfactants. In selecting a suitable benchmark surfactant, two metrics are examined: the ability of the surfactants to alter wettability at low concentrations, and the degree to which they are absorbed onto reservoir matrix. We review the literature to survey the adsorption models that have been developed to describe surfactant adsorption in porous media. These models are evaluated using the experimental data from this study. Crushed carbonate rock samples are cleaned and aged in crude oil. The wettability change mediated by dilute solutions of commercial anionic surfactants and surfactin is assessed using a two-phase separation; and surfactant loss due to retention and adsorption the rock is determined.

  16. CAPILLARY ELECTROPHORETIC BEHAVIOR OF SEVEN SULFONYLUREAS

    EPA Science Inventory

    The electrophoretic behavior of bensulfuron Me, sulfometuron Me, nicosulfuron (Accent), chlorimuron Et, thifensulfuron Me (Harmony), metsulfuron Me, and chlorsulfuron was studied under capillary zone electrophoresis (CZE) and micellar electrokinetic chromatography (MEKC) conditio...

  17. DNA sequencing using capillary array electrophoresis

    SciTech Connect

    Huang, X.C.; Quesada, M.A.; Mathies, R.A.

    1992-09-15

    A DNA sequencing method is presented that utilizes capillary array electrophoresis, two-color fluorescence detection, and a two-dye labeling protocol. Sanger DNA sequencing fragments are separated on an array of capillaries and detected on-column using a two-color, laser-excited, confocal-fluorescence scanner. The four set of DNA sequencing fragments are separated in a single capillary and then distinguished by using a binary coding scheme where each fragment set is labeled with a characteristic ratio of two dye-labeled primers. Since only two dye-labeled primers are required, it is possible to select dyes that have identical mobility shifts. It is also shown that the ratio of the signal in the two detection channels provides a reliable identification of the sequencing fragment. DNA sequencing results on a 25-capillary array are presented. 30 refs., 6 figs, 1 tab.

  18. Multistaged stokes injected Raman capillary waveguide amplifier

    DOEpatents

    Kurnit, Norman A.

    1980-01-01

    A multistaged Stokes injected Raman capillary waveguide amplifier for providing a high gain Stokes output signal. The amplifier uses a plurality of optically coupled capillary waveguide amplifiers and one or more regenerative amplifiers to increase Stokes gain to a level sufficient for power amplification. Power amplification is provided by a multifocused Raman gain cell or a large diameter capillary waveguide. An external source of CO.sub.2 laser radiation can be injected into each of the capillary waveguide amplifier stages to increase Raman gain. Devices for injecting external sources of CO.sub.2 radiation include: dichroic mirrors, prisms, gratings and Ge Brewster plates. Alternatively, the CO.sub.2 input radiation to the first stage can be coupled and amplified between successive stages.

  19. CAPILLARY BARRIERS IN UNSATURATED FRACTURED ROCKS

    SciTech Connect

    Y.S. Wu; W. Zhang; L. Pan; J. Hinds; G. Bodvarsson

    2000-10-01

    This work presents modeling studies investigating the effects of capillary barriers on fluid-flow and tracer-transport processes in the unsaturated zone of Yucca Mountain, Nevada, a potential site for storing high-level radioactive waste. These studies are designed to identify factors controlling the formation of capillary barriers and to estimate their effects on the extent of possible large-scale lateral flow in unsaturated fracture rocks. The modeling approach is based on a continuum formulation of coupled multiphase fluid and tracer transport through fractured porous rock. Flow processes in fractured porous rock are described using a dual-continuum concept. In addition, approximate analytical solutions are developed and used for assessing capillary-barrier effects in fractured rocks. This study indicates that under the current hydrogeologic conceptualization of Yucca Mountain, strong capillary-barrier effects exist for significantly diverting moisture flow.

  20. Capillary electrochromatography using fibers as stationary phases.

    PubMed

    Jinno, K; Watanabe, H; Saito, Y; Takeichi, T

    2001-10-01

    Fiber-packed capillary columns have been evaluated in chromatographic performance in capillary electrochromatography (CEC). The change of electroosmotic flow (EOF) velocity and selectivity using different kinds of fiber materials was examined. Although the EOF velocity among the different fiber packed columns was almost the same, retention of parabens was larger on the Kevlar-packed column than on the Zylon-packed one, and was larger on the as-span-type fiber-packed column than on the high-modulus-type packed one. Using 200 microm ID x 5 cm Kevlar packed column combined with a 100 microm ID x 20 cm precolumn capillary and a 530 microm ID x 45 cm postcolumn capillary, the separation of three parabens within 30 s was achieved. Other compounds were also separated in a few minutes by the fiber-packed CEC method. PMID:11669512

  1. Capillary Flow Resistors: Local and Global Resistors.

    PubMed

    Berthier, Jean; Gosselin, David; Pham, Andrew; Delapierre, Guillaume; Belgacem, Naceur; Chaussy, Didier

    2016-01-26

    The use of capillary systems in space and biotechnology applications requires the regulation of the capillary flow velocity. It has been observed that constricted sections act as flow resistors. In this work, we also show that enlarged sections temporarily reduce the velocity of the flow. In this work, the theory of the dynamics of capillary flows passing through a constricted or an enlarged channel section is presented. It is demonstrated that the physics of a capillary flow in a channel with a constriction or an enlargement is different and that a constriction acts as a global flow resistor and an enlargement as a local flow resistor. The theoretical results are checked against experimental approaches. PMID:26704147

  2. Characterising Microstructured Materials Using a Capillary Rheometer

    NASA Astrophysics Data System (ADS)

    Hicks, Christopher I.; See, Howard; Arabo, Emad Y. M.

    2008-07-01

    A parallel plate and capillary rheometer have been used to rheologically characterize an Australian hard wheat flour-water dough over an extensive range of shear rates (10-3-104 s-1). Torsional measurements showed that the shear viscosity of dough increased with strain to a maximum value then decreased, suggesting a breakdown of the dough structure. This was consistent with other published data on doughs. Capillary experiments revealed the shear thinning behavior of dough, which was described by a power-law model. The wall slip behavior of dough was examined, revealing a critical shear stress at which slip occurs for a 1 mm diameter capillary. The capillary data was best linked to the torsional data at low strain values (0.1) as expected given the nature of sampling in the two rheometers.

  3. Thin film capillary process and apparatus

    DOEpatents

    Yu, Conrad M.

    2003-11-18

    Method and system of forming microfluidic capillaries in a variety of substrate materials. A first layer of a material such as silicon dioxide is applied to a channel etched in substrate. A second, sacrificial layer of a material such as a polymer is deposited on the first layer. A third layer which may be of the same material as the first layer is placed on the second layer. The sacrificial layer is removed to form a smooth walled capillary in the substrate.

  4. A single-probe capillary microgripper induced by dropwise condensation and inertial release

    NASA Astrophysics Data System (ADS)

    Fan, Zenghua; Rong, Weibin; Wang, Lefeng; Sun, Lining

    2015-11-01

    A micromanipulation method based on liquid droplets is widely used as a non-destructive technology to pick-and-place micrometer-scale objects. We focus on the development of a single-probe capillary microgripper to execute reliable micromanipulation tasks. By controlling dropwise condensation on a probe tip, the water droplet volume on the hydrophobic tip surface can be varied dynamically, which helps establish appropriate capillary lifting forces during capturing tasks. An inertia-releasing strategy was utilized to implement a piezoelectric actuator integrated with the capillary microgripper and to address release problems caused by adhesion force action. The influence of droplet formation and the capillary lifting force generated during the manipulation process were characterized experimentally. Micromanipulation tests were conducted using a customized motion platform with viewing microscopes to verify the performance potential of the capillary microgripping tool. Experimental results indicated that polystyrene microspheres with 20-100 μm radii and micro-silicon chips (1.63-12.1 μN) were grasped reliably, and that adhered micro-objects could be placed on a target using the proposed microhandling technique of inertial release in ambient conditions.

  5. Particulate matter contamination of intravenous antibiotics aggravates loss of functional capillary density in postischemic striated muscle.

    PubMed

    Lehr, Hans-Anton; Brunner, Joachim; Rangoonwala, Ramzan; Kirkpatrick, C James

    2002-02-15

    Through the increased use of less expensive and counterfeit medicines, the contamination of parenteral fluids and drugs by particulate matter poses an increasing health hazard worldwide. However, the mechanism of action of such contamination has never been conclusively demonstrated. We have systemically injected the particles contained in three different 1-g preparations of the antibiotic cefotaxime into hamsters and visualized the functional capillary density in striated skin muscle, using intravital fluorescence microscopy. Injection of particles from either of the three preparations did not affect capillary perfusion in normal muscle (n = 3 hamsters, each). However, injection of particles from two generic drug preparations, but not the original preparation or the saline control, significantly reduced capillary perfusion in muscle tissue that had previously been exposed to 4 h of pressure-induced ischemia and 2 h of reperfusion (n = 9 hamsters per group). Histological sections demonstrated birefringent particles mechanically obliterating the microcirculation of the striated muscle. The loss of capillary perfusion due to particle injection or injection of standardized microspheres was dependent on the extent of ischemia/reperfusion-induced muscle injury, with more capillaries lost in the more severely compromised muscle areas. These findings suggest that particle contaminants may not pose a major threat in intact tissue, but may severely compromise tissue perfusion in patients with prior microvascular compromise of vital organs (i.e., after trauma, major surgery, or sepsis) and thus predispose to complications such as acute respiratory distress syndrome or multiple organ failure. PMID:11850345

  6. Capillary attraction between floating cylinders

    NASA Astrophysics Data System (ADS)

    Dixit, Harish; Homsy, George M. (Bud)

    2011-11-01

    Capillary attraction between floating particles is a phenomenon of everyday experience and causes the particles at fluid interfaces to agglomerate. This is sometimes called the ``Cheerios effect.'' The calculation of the force of attraction for even simple particle shapes is enormously difficult due to the presence of nonlinearity in the equations governing the interface shape. Most of the earlier approaches to obtained analytical expression for the force of attraction rely on the ``superposition principle'' by linearizing the Young-Laplace equation. We use a systematic perturbation technique in the limit of small Bond number. We present asymptotic solutions in a static configuration obtained for two problems: (i) attraction between two isolated cylinders, and (ii) attraction for an infinite array of cylinders. It is also found that the background curvature of an interface modifies the force of attraction. These forces are important in many technological applications: one such example is the problem of dip-coating of plates which will be discussed during the meeting.

  7. Capillary electrophoresis of phytochemical substances.

    PubMed

    Suntornsuk, Leena

    2002-02-01

    Applications of capillary electrophoresis (CE) for analysis of phytochemical substances (e.g. flavonoids, alkaloids, terpenoids, phenolic acid, quinones and coumarins) are reviewed. For example, CE analysis of sixteen tea ingredients were achieved within 10 min with the good precision (RSDs% <1% for intra-day and 2% for inter-day) and linearity (R(2)>0.990). Quantitation of sanguinarine and chelerythrine, alkaloids from Sanguinaria canadensis L. or Macleaya cordata (Wild) Br. R. by CE showed excellent linearity (R(2)>0.998), precision (RSD%=1.8%) and detection limit (2.4-3.0 microM). Determination of antraquinone-1-sulphonate was also obtained by this technique with good linearity (R(2)>0.9999), precision (RSD%=2%) and detection limit (0.7 microg/ml). Results of CE analysis from several studies are comparable to those of high performance liquid chromatography (HPLC), but the former is more useful for complex mixture samples where the analysis demands higher resolving power. Advantages of CE are high efficiency, low cost, short analysis time and simplicity, whereas disadvantages include low sensitivity comparing to HPLC and limitation of the preparative scale. PMID:11814710

  8. Nonlinear waves in capillary electrophoresis

    PubMed Central

    Ghosal, Sandip; Chen, Zhen

    2011-01-01

    Electrophoretic separation of a mixture of chemical species is a fundamental technique of great usefulness in biology, health care and forensics. In capillary electrophoresis the sample migrates in a microcapillary in the presence of a background electrolyte. When the ionic concentration of the sample is sufficiently high, the signal is known to exhibit features reminiscent of nonlinear waves including sharp concentration shocks. In this paper we consider a simplified model consisting of a single sample ion and a background electrolyte consisting of a single co-ion and a counterion in the absence of any processes that might change the ionization states of the constituents. If the ionic diffusivities are assumed to be the same for all constituents the concentration of sample ion is shown to obey a one dimensional advection diffusion equation with a concentration dependent advection velocity. If the analyte concentration is sufficiently low in a suitable non-dimensional sense, Burgers equation is recovered, and thus, the time dependent problem is exactly solvable with arbitrary initial conditions. In the case of small diffusivity either a leading edge or trailing edge shock is formed depending on the electrophoretic mobility of the sample ion relative to the background ions. Analytical formulas are presented for the shape, width and migration velocity of the sample peak and it is shown that axial dispersion at long times may be characterized by an effective diffusivity that is exactly calculated. These results are consistent with known observations from physical and numerical simulation experiments. PMID:20238181

  9. Multiple capillary biochemical analyzer with barrier member

    DOEpatents

    Dovichi, Norman J. (Edmonton, CA); Zhang, Jian Z. (Edmonton, CA)

    1996-01-01

    A multiple capillary biochemical analyzer for sequencing DNA and performing other analyses, in which a set of capillaries extends from wells in a microtiter plate into a cuvette. In the cuvette the capillaries are held on fixed closely spaced centers by passing through a sandwich construction having a pair of metal shims which squeeze between them a rubber gasket, forming a leak proof seal for an interior chamber in which the capillary ends are positioned. Sheath fluid enters the chamber and entrains filament sample streams from the capillaries. The filament sample streams, and sheath fluid, flow through aligned holes in a barrier member spaced close to the capillary ends, into a collection chamber having a lower glass window. The filament streams are illuminated above the barrier member by a laser, causing them to fluoresce. The fluorescence is viewed end-on by a CCD camera chip located below the glass window. The arrangement ensures an equal optical path length from all fluorescing spots to the CCD chip and also blocks scattered fluorescence illumination, providing more uniform results and an improved signal to noise ratio.

  10. Multiple capillary biochemical analyzer with barrier member

    DOEpatents

    Dovichi, N.J.; Zhang, J.Z.

    1996-10-22

    A multiple capillary biochemical analyzer is disclosed for sequencing DNA and performing other analyses, in which a set of capillaries extends from wells in a microtiter plate into a cuvette. In the cuvette the capillaries are held on fixed closely spaced centers by passing through a sandwich construction having a pair of metal shims which squeeze between them a rubber gasket, forming a leak proof seal for an interior chamber in which the capillary ends are positioned. Sheath fluid enters the chamber and entrains filament sample streams from the capillaries. The filament sample streams, and sheath fluid, flow through aligned holes in a barrier member spaced close to the capillary ends, into a collection chamber having a lower glass window. The filament streams are illuminated above the barrier member by a laser, causing them to fluoresce. The fluorescence is viewed end-on by a CCD camera chip located below the glass window. The arrangement ensures an equal optical path length from all fluorescing spots to the CCD chip and also blocks scattered fluorescence illumination, providing more uniform results and an improved signal-to-noise ratio. 12 figs.

  11. Capillary fracture of soft gels.

    PubMed

    Bostwick, Joshua B; Daniels, Karen E

    2013-10-01

    A liquid droplet resting on a soft gel substrate can deform that substrate to the point of material failure, whereby fractures develop on the gel surface that propagate outwards from the contact line in a starburst pattern. In this paper, we characterize (i) the initiation process, in which the number of arms in the starburst is controlled by the ratio of the surface tension contrast to the gel's elastic modulus, and (ii) the propagation dynamics showing that once fractures are initiated they propagate with a universal power law L[proportional]t(3/4). We develop a model for crack initiation by treating the gel as a linear elastic solid and computing the deformations within the substrate from the liquid-solid wetting forces. The elastic solution shows that both the location and the magnitude of the wetting forces are critical in providing a quantitative prediction for the number of fractures and, hence, an interpretation of the initiation of capillary fractures. This solution also reveals that the depth of the gel is an important factor in the fracture process, as it can help mitigate large surface tractions; this finding is confirmed with experiments. We then develop a model for crack propagation by considering the transport of an inviscid fluid into the fracture tip of an incompressible material and find that a simple energy-conservation argument can explain the observed material-independent power law. We compare predictions for both linear elastic and neo-Hookean solids, finding that the latter better explains the observed exponent. PMID:24229192

  12. Slope wavenumber spectrum models of capillary and capillary-gravity waves

    NASA Astrophysics Data System (ADS)

    Jia, Yongjun; Zhang, Jie; Wang, Yanfeng

    2010-03-01

    Capillary and capillary-gravity waves possess a random character, and the slope wavenumber spectra of them can be used to represent mean distributions of wave energy with respect to spatial scale of variability. But simple and practical models of the slope wavenumber spectra have not been put forward so far. In this article, we address the accurate definition of the slope wavenumber spectra of water surface capillary and capillary-gravity waves. By combining the existing slope wavenumber models and using the dispersion relation of water surface waves, we derive the slope wavenumber spectrum models of capillary and capillary-gravity waves. Simultaneously, by using the slope wavenumber models, the dependence of the slope wavenumber spectrum on wind speed is analyzed using data obtained in an experiment which was performed in a laboratory wind wave tank. Generally speaking, the slope wavenumber spectra are influenced profoundly by the wind speed above water surface. The slope wavenumber spectrum increases with wind speed obviously and do not cross each other for different wind speeds. But, for the same wind speed, the slope wavenumber spectra are essentially identical, even though the capillary and capillary-gravity waves are excited at different times and locations. Furthermore, the slope wavenumber spectra obtained from the models agree quite well with experimental results as regards both the values and the shape of the curve.

  13. N2 and CO2 capillary breakthrough experiments on Opalinus Clay

    NASA Astrophysics Data System (ADS)

    Amann, Alexandra; Busch, Andreas; Krooss, Bernhard M.

    2013-04-01

    The aim of this project was to identify the critical capillary pressures on the drainage and the imbibition path for clay-rich rocks, at a burial depth of 1500 m (30 MPa confining pressure, 45C). The experiments were performed on fully water-saturated sample plugs of 38 mm diameter and 5 to 20 mm length. The capillary breakthrough pressure was determined by step-wise increase of the differential pressure (drainage), the capillary snap-off pressure was determined from the final pressure difference at the end of a spontaneous imbibition phase. The confining pressure was kept constant throughout the experiment, which resulted in a continuous change of effective stress. The measurements were performed in a closed system and the pressure response was interpreted in terms of different flow mechanisms (diffusion-controlled vs. viscous flow). In total, four breakthrough experiments with N2 and five experiments with CO2 were conducted. Because of very low flow rates and high critical capillary pressures the experiments took rather long. In some cases the experiments were allowed to run for half a year (drainage experiments). Substantial differences were observed between gas breakthrough (drainage) and snap-off (imbibition) pressures. As expected, breakthrough pressures were always higher than the snap-off pressures. For three samples a pbreakthrough/psnap-off ratio of 1.6 to 1.9 was observed, for one sample a ratio of 4. A clear permeability-capillary pressure relationship could not be identified. Based on (omnidirectional) Hg-injection porosimetry results, and assuming perfectly water wet mineral surfaces, gas breakthrough pressures were predicted to occur at approximately 16 MPa for N2 and 5.7 MPa for CO2. The gas breakthrough experiments, however, produced different results. Even though a relatively homogeneous sample set was chosen, with permeability coefficients ranging between 1E-21 and 6E-21 m, the critical capillary breakthrough pressures for nitrogen ranged between 3.4 and 12.3 MPa and snap-off pressures from 0.5 to 6.4 MPa. The CO2 experiments yielded breakthrough pressures of 14.0 to 17.5 MPa and snap-off pressures of 3.5 to 10 MPa. No significant changes in single-phase water permeability coefficients before and after the gas breakthrough experiments were observed. In our contribution we will discuss the following points: 1. Gas fluxes occurring during gas breakthrough experiments may be extremely low. Therefore an unambigous identification of gas breakthrough is not always possible. Besides viscous or diffusive transport, dissolution of CO2 in the pore water may affect the observed pressure changes in the upstream and downstream compartments. All of these processes occur simultaneously and can only be partly discriminated. Gas fluxes detected during the diffusion-controlled flow regimes result in nominal effective gas permeability coefficients as low as 6E-25 m to 7E-24m. 2. The application of purely capillary-controlled flow models may not be justified. o Gas breakthrough is controlled by effective stress, i.e. the opening of pores or small fissures. o Assumptions about wettability (completely water-wet mineral surfaces) may be incorrect.

  14. Critical Velocities in Open Capillary Flow

    NASA Technical Reports Server (NTRS)

    Dreyer, Michael; Langbein, Dieter; Rath, Hans J.

    1996-01-01

    This paper describes the proposed research program on open capillary flow and the preliminary work performed theoretically and in drop tower experiments. The work focuses on the fundamental physical understanding of the flow through capillary bound geometries, where the circumference of the cross section of the flow path contains free surfaces. Examples for such a flow configuration are capillary vanes in surface tension tanks, flow along edges and corners and flow through liquid bridges. The geometries may be classified by their cross section areas, wetted circumferences and the radii of curvature of the free surfaces. In the streaming float zone the flow path is bound by a free surface only. The ribbon vane is a model for vane types used in surface tension tanks, where a structure in proximity to the tank wall forms a capillary gap. A groove is used in heat pipes for the transportation of the condensed working fluid to the heat source and a wedge may occur in a spaceborne experiment where fluid has to be transported by the means of surface tension. The research objectives are the determination of the maximum volume flux, the observation of the free surfaces and the liquid flow inside the flow path as well as the evaluation of the limiting capillary wave speed. The restriction of the maximum volume flux is due to convective forces (flow velocity exceeding the capillary wave speed) and/or viscous forces, i.e. the viscous head loss along the flow path must be compensated by the capillary pressure due to the curved free surface. Exceeding the maximum volume flux leads to the choking of the flow path, thus the free surface collapses and.gas ingestion occurs at the outlet. The means are ground-based experimental work with plateau tanks and in a drop tower, a sounding rocket flight, and theoretical analysis with integral balances as well as full three dimensional CFD solutions for flow with free surfaces.

  15. High speed and reproducible analysis of nitrosamines by capillary electrophoresis with a sulfonated capillary.

    PubMed

    Taga, Atsushi; Nishi, Tomoko; Honda, Yoshitaka; Sato, Atsushi; Terashima, Hiroyuki; Suzuki, Kentaro; Kodama, Shuji; Boki, Keito

    2007-01-01

    Recently environmental control is regarded as important for good human health conditions, and toxic substances, including carcinogens and endocrine disruptors should be eliminated from our living environment. Hence easy quantitative methods are expected for a high level of environmental control. Our previous paper describes an easy quantitative analysis of nitrosamines (NAs) by capillary electrophoresis with an untreated fused silica capillary installed in an ordinary apparatus. In this paper, utilizing a novel type capillary column having sulfonated inner wall was investigated for improvements of separation performance and reproducibility. A sulfonated capillary causes fast and stabile electroosmotic flow because its inner wall is strongly negative charged. On a performance comparison of a sulfonated capillary with an untreated fused silica, analysis time reduction of c.a. forty percent was achieved, and relative standard deviations of migration times and peak responses were less than one third. In addition sample concentrations giving detection and quantitation limits were also reduced to a half. PMID:17898509

  16. Carbonic anhydrase--a marker for fenestrated capillaries in psoriasis.

    PubMed

    Jungkunz, W; Eichhorn, M; Wrl, J; Marsch, W C; Holzmann, H

    1992-01-01

    A strong correlation between capillary fenestrations and the demonstration of carbonic anhydrase (CA) has previously been shown. In the present histochemical study we sought to determine whether CA could serve as a marker for fenestrated capillaries in psoriasis. In normal human skin capillary staining for CA was found only in the fenestrated capillaries of the perifollicular and periglandular plexus. In psoriatic skin lesions, however, the intrapapillary capillaries also reacted for CA. From ultrastructural investigations it is known that these capillaries are fenestrated. Our findings have shown that there is a strong correlation between fenestrated and CA-positive capillaries in normal human skin as well as in the lesional skin of psoriatics. Therefore, the demonstration of CA activity may serve as a specific and sensitive marker for fenestrated capillaries in psoriasis using an uncomplicated method, which makes it possible to detect numerous fenestrated capillaries in a single histological section. PMID:1503498

  17. Capillary liquid chromatography using laser-based and mass spectrometric detection. [Capillary zone electrophoresis (CZE); micellar electrokinetic capillary kchromatography (MECC)

    SciTech Connect

    Sepaniak, M.J.; Cook, K.D.

    1992-01-01

    In the years following the 1986 seminal paper (J. Chromatogr. Sci., 24, 347-352) describing modern capillary zone electrophoresis (CZE), the prominence of capillary electrokinetic separation techniques has grown. A related electrochromatographic technique is micellar electrokinetic capillary chromatography (MECC). This report presents a brief synopsis of research efforts during the current 3-year period. In addition to a description of analytical separations-based research, results of efforts to develop and expand spectrometric detection for the techniques is reviewed. Laser fluorometric detection schemes have been successfully advanced. Mass spectrometric research was less fruitful, largely owing to personnel limitations. A regenerable fiber optic sensor was developed that can be used to remotely monitor chemical carcinogens, etc. (DLC)

  18. Passive Reactor Cooling Using Capillary Porous Wick

    SciTech Connect

    Miller, Christopher G.; Lin, Thomas F.

    2006-07-01

    Long-term reliability of actively pumped cooling systems is a concern in space-based nuclear reactors. Capillary-driven passive cooling systems are being considered as an alternative to gravity-driven systems. The high surface tension of liquid lithium makes it attractive as the coolant in a capillary-driven cooling system. A system has been conceived in which the fuel rod of a reactor is surrounded by a concentric wick through which liquid lithium flows to provide cooling under normal and emergency operating conditions. Unheated wicking experiments at three pressures using four layered screen mesh wicks of different porosities and three relatively high surface tension fluids have been conducted to gain insight into capillary phenomena for such a capillary cooling system. All fluids tested demonstrated wicking ability in each of the wick structures for all pressures, and wicking ability for each fluid increased with decreasing wick pore size. An externally heated wicking experiment with liquid lithium as the wicking fluid was also conducted. In addition to wicking experiments, a heater rod is under development to simulate the fuel rod of a space based nuclear reactor by providing a heat flux of up to 110 kW/m{sup 2}. Testing of this heater rod has shown its ability to undergo repeated cycling from below 533 K to over 1255 K without failure. This heater rod will be integrated into lithium wicking experiments to provide more realistic simulation of the proposed capillary-driven space nuclear reactor cooling system. (authors)

  19. Micro-injector for capillary electrophoresis.

    PubMed

    Siz, Jorge; Koenka, Israel Joel; Garca-Ruiz, Carmen; Mller, Beat; Chwalek, Thomas; Hauser, Peter C

    2015-08-01

    A novel micro-injector for capillary electrophoresis for the handling of samples with volumes down to as little as 300 nL was designed and built in our laboratory for analyses in which the available volume is a limitation. The sample is placed into a small cavity located directly in front of the separation capillary, and the injection is then carried out automatically by controlled pressurization of the chamber with compressed air. The system also allows automated flushing of the injection chamber as well as of the capillary. In a trial with a capillary electrophoresis system with contactless conductivity detector, employing a capillary of 25 ?m diameter, the results showed good stability of migration times and peak areas. To illustrate the technique, the fast separation of five inorganic cations (Na(+) , K(+) , NH4 (+) , Ca(2+) , and Mg(2+) ) was set up. This could be achieved in less than 3 min, with good limits of detection (10 ?M) and linear ranges (between about 10 and 1000 ?M). The system was demonstrated for the determination of the inorganic cations in porewater samples of a lake sediment core. PMID:25752271

  20. Switchable capillary bridges in sphere packings

    NASA Astrophysics Data System (ADS)

    Ggelein, Christoph; Brinkmann, Martin; Schrter, Matthias; Herminghaus, Stephan

    2011-03-01

    If one adds a small amount of water to a heap of sand, it becomes paste-like since the grains get interconnected by capillary bridges. Due to this effect, we can easily sculpture wet sand (e.g., building a sand castle), whereas a heap of dry grains ripples away and cannot sustain any shape. In the present work, we use a non-Brownian suspension of glass spheres immersed in a binary liquid mixture. The suspending water-lutidine mixture exhibits a well studied lower critical point slightly above ambient temperature. Hence, the mixture starts to phase separate upon heating. Since the water-rich phase wets the hydrophilic glass spheres, capillary bridges are formed between adjacent particles. If the system is cooled below the demixing temperature, the bridges disappear within a few seconds by intermolecular diffusion. Thus, this systems offers the opportunity to switch the capillary bridges on and off by altering the temperature. In this presentation, we will show the temperature-induced formation of capillary bridges using confocal and bright light microscopy. Furthermore, we will discuss the effect of capillary bridges on random sphere packings using a fluidized bed setup.

  1. Synthetic Capillaries to Control Microscopic Blood Flow

    PubMed Central

    Sarveswaran, K.; Kurz, V.; Dong, Z.; Tanaka, T.; Penny, S.; Timp, G.

    2016-01-01

    Capillaries pervade human physiology. The mean intercapillary distance is only about 100 μm in human tissue, which indicates the extent of nutrient diffusion. In engineered tissue the lack of capillaries, along with the associated perfusion, is problematic because it leads to hypoxic stress and necrosis. However, a capillary is not easy to engineer due to its complex cytoarchitecture. Here, it is shown that it is possible to create in vitro, in about 30 min, a tubular microenvironment with an elastic modulus and porosity consistent with human tissue that functionally mimicks a bona fide capillary using “live cell lithography”(LCL) to control the type and position of cells on a composite hydrogel scaffold. Furthermore, it is established that these constructs support the forces associated with blood flow, and produce nutrient gradients similar to those measured in vivo. With LCL, capillaries can be constructed with single cell precision—no other method for tissue engineering offers such precision. Since the time required for assembly scales with the number of cells, this method is likely to be adapted first to create minimal functional units of human tissue that constitute organs, consisting of a heterogeneous population of 100–1000 cells, organized hierarchically to express a predictable function. PMID:26905751

  2. Synthetic Capillaries to Control Microscopic Blood Flow

    NASA Astrophysics Data System (ADS)

    Sarveswaran, K.; Kurz, V.; Dong, Z.; Tanaka, T.; Penny, S.; Timp, G.

    2016-02-01

    Capillaries pervade human physiology. The mean intercapillary distance is only about 100 μm in human tissue, which indicates the extent of nutrient diffusion. In engineered tissue the lack of capillaries, along with the associated perfusion, is problematic because it leads to hypoxic stress and necrosis. However, a capillary is not easy to engineer due to its complex cytoarchitecture. Here, it is shown that it is possible to create in vitro, in about 30 min, a tubular microenvironment with an elastic modulus and porosity consistent with human tissue that functionally mimicks a bona fide capillary using “live cell lithography”(LCL) to control the type and position of cells on a composite hydrogel scaffold. Furthermore, it is established that these constructs support the forces associated with blood flow, and produce nutrient gradients similar to those measured in vivo. With LCL, capillaries can be constructed with single cell precision—no other method for tissue engineering offers such precision. Since the time required for assembly scales with the number of cells, this method is likely to be adapted first to create minimal functional units of human tissue that constitute organs, consisting of a heterogeneous population of 100–1000 cells, organized hierarchically to express a predictable function.

  3. Modeling aerobic biodegradation in the capillary fringe.

    PubMed

    Luo, Jian; Kurt, Zohre; Hou, Deyi; Spain, Jim C

    2015-02-01

    Vapor intrusion from volatile subsurface contaminants can be mitigated by aerobic biodegradation. Laboratory column studies with contaminant sources of chlorobenzene and a mixture of chlorobenzene, 1,2-dichlorobenzene, and 1,4-dichlorobenzene showed that contaminants were rapidly degraded in thin reactive zones with high biomass and low substrate concentrations in the vicinity of the capillary fringe. Such behavior was well characterized by a model that includes oxygen-, substrate-, and biomass-dependent biodegradation kinetics along with diffusive transport processes. An analytical solution was derived to provide theoretical support for the simplification of reaction kinetics and the approximation of reactive zone location and mass flux relationships at steady state. Results demonstrate the potential of aerobic natural attenuation in the capillary fringe for preventing contaminant migration in the unsaturated zone. The solution indicates that increasing contaminant mass flux into the column creates a thinner reactive zone and pushes it toward the oxygen boundary, resulting in a shorter distance to the oxygen source and a larger oxygen mass flux that balances the contaminant mass flux. As a consequence, the aerobic biodegradation can reduce high contaminant concentrations to low levels within the capillary fringe and unsaturated zone. The results are consistent with the observations of thin reactive layers at the interface in unsaturated zones. The model considers biomass while including biodegradation in the capillary fringe and unsaturated zone and clearly demonstrates that microbial communities capable of using the contaminants as electron donors may lead to instantaneous degradation kinetics in the capillary fringe and unsaturated zone. PMID:25548946

  4. Restructuring and aging in a capillary suspension

    PubMed Central

    Koos, Erin; Kannowade, Wolfgang; Willenbacher, Norbert

    2014-01-01

    The rheological properties of capillary suspensions, suspensions with small amounts of an added immiscible fluid, are dramatically altered with the addition of the secondary fluid. We investigate a capillary suspension to determine how the network ages and restructures at rest and under applied external shear deformation. The present work uses calcium carbonate suspended in silicone oil (11 % solids) with added water as a model system. Aging of capillary suspensions and their response to applied oscillatory shear is distinctly different from particulate gels dominated by the van der Waals forces. The suspensions dominated by the capillary force are very sensitive to oscillatory flow, with the linear viscoelastic regime ending at a deformation of only 0.1% and demonstrating power-law aging behavior. This aging persists for long times at low deformations or for shorter times with a sudden decrease in the strength at higher deformations. This aging behavior suggests that the network is able to rearrange and even rupture. This same sensitivity is not demonstrated in shear flow where very high shear rates are required to rupture the agglomerates returning the apparent viscosity of capillary suspensions to the same viscosity as for the pure vdW suspension. A transitional region is also present at intermediate water contents wherein the material response depends very strongly on the type, strength, and duration of the external forcing. PMID:25729113

  5. Capillary effects on floating cylindrical particles

    NASA Astrophysics Data System (ADS)

    Dixit, Harish N.; Homsy, G. M.

    2012-12-01

    In this study, we develop a systematic perturbation procedure in the small parameter, B1/2, where B is the Bond number, to study capillary effects on small cylindrical particles at interfaces. Such a framework allows us to address many problems involving particles on flat and curved interfaces. In particular, we address four specific problems: (i) capillary attraction between cylinders on flat interface, in which we recover the classical approximate result of Nicolson ["The interaction between floating particles," Proc. Cambridge Philos. Soc. 45, 288-295 (1949), 10.1017/S0305004100024841], thus putting it on a rational basis; (ii) capillary attraction and aggregation for an infinite array of cylinders arranged on a periodic lattice, where we show that the resulting Gibbs elasticity obtained for an array can be significantly larger than the two cylinder case; (iii) capillary force on a cylinder floating on an arbitrary curved interface, where we show that in the absence of gravity, the cylinder experiences a lateral force which is proportional to the gradient of curvature; and (iv) capillary attraction between two cylinders floating on an arbitrary curved interface. The present perturbation procedure does not require any restrictions on the nature of curvature of the background interface and can be extended to other geometries.

  6. Capillary sensors: a design concept for optrodes

    NASA Astrophysics Data System (ADS)

    Weigl, Bernhard H.; Wolfbeis, Otto S.

    1994-10-01

    We describe the use of glass or plastic capillaries in optical chemical sensing. They possess several attractive features in that (a) they can act as a mechanical support for optically sensitive materials (coatings); (b), they represent an optical waveguide structure and enable various methods of optical interrogation; and (c) they can serve as a sample cavity of well-defined volume and are suitable for direct sampling, e.g. when drawing blood. The method of immobilization and the performance of such 'capillary sensors' is exemplified by a fast- responding carbon dioxide sensor chemistry. Its response times vary from 100 to 300 ms. Such capillary sensors have, in general, extremely short response times for three reasons, namely (a), because the two sensing layers passed by the light beam when penetrating the capillary can be made very thin; (b), equilibration of two thin layers is faster than that of a single layer of the same total thickness; and (c), the sample flow is laminar, resulting in a fast and homogeneous exchange of sample volume. We also give arrangements for optical readout devices and show that capillary sensors can overcome some of the problems of optrode membranes mounted in flow cells or on fiber tips.

  7. EUV radiation from nitrogen capillary discharge

    NASA Astrophysics Data System (ADS)

    Frolov, Oleksandr; Kolacek, Karel; Schmidt, Jiri; Straus, Jaroslav

    2014-08-01

    In the last decade EUV sources attract interest from researchers over the world. One of the main motivations is EUV lithography, which could lead to further miniaturization in electronics. Nitrogen recombination laser at wavelength of 13.4 nm based on capillary discharge Z-pinch configuration could be used in experiments with testing of resolution of photoresist for EUV lithography (close to wavelength of 13.5 nm Si/Mo multilayer mirrors have a high reflectivity at normal incidence angles). In this work, pinching of nitrogen-filled capillary discharge is studied for the development of EUV laser, which is based on recombination pumping scheme. The goal of this study is achieving the required plasma conditions using a capillary discharge Z-pinch apparatus. In experiments with nitrogen, the capillary length was shortened from 232 mm to 90 mm and current quarter-period was changed from 60 ns to 50 ns in contrast with early experiments with Ne-like argon laser. EUV radiation from capillary discharge was registered by X-ray vacuum diode for different pressure, amplitude and duration of pre-pulse and charging voltage of the Marx generator.

  8. Synthetic Capillaries to Control Microscopic Blood Flow.

    PubMed

    Sarveswaran, K; Kurz, V; Dong, Z; Tanaka, T; Penny, S; Timp, G

    2016-01-01

    Capillaries pervade human physiology. The mean intercapillary distance is only about 100??m in human tissue, which indicates the extent of nutrient diffusion. In engineered tissue the lack of capillaries, along with the associated perfusion, is problematic because it leads to hypoxic stress and necrosis. However, a capillary is not easy to engineer due to its complex cytoarchitecture. Here, it is shown that it is possible to create in vitro, in about 30 min, a tubular microenvironment with an elastic modulus and porosity consistent with human tissue that functionally mimicks a bona fide capillary using "live cell lithography"(LCL) to control the type and position of cells on a composite hydrogel scaffold. Furthermore, it is established that these constructs support the forces associated with blood flow, and produce nutrient gradients similar to those measured in vivo. With LCL, capillaries can be constructed with single cell precision-no other method for tissue engineering offers such precision. Since the time required for assembly scales with the number of cells, this method is likely to be adapted first to create minimal functional units of human tissue that constitute organs, consisting of a heterogeneous population of 100-1000 cells, organized hierarchically to express a predictable function. PMID:26905751

  9. WETTABILITY ALTERATION OF POROUS MEDIA TO GAS-WETTING FOR IMPROVING PRODUCTIVITY AND INJECTIVITY IN GAS-LIQUID FLOWS

    SciTech Connect

    Abbas Firoozabadi

    2001-10-15

    The wettability of Berea and chalk samples for gas-oil and gas-water fluids were altered from strong liquid-wetting to intermediate gas-wetting. Two polymers, FC-722 and FC-759, were used to alter the wettability. FC-759 is soluble in water and some 20 times less expensive than FC-722. Gas and liquid relative permeabilities were measured before and after wettability alteration. The results demonstrate a significant increase in liquid-phase relative permeability. Gas-phase relative permeability for a fixed saturation may increase or decrease. However, because of the very high liquid mobility and reduced liquid saturation, the gas mobility also increases for a fixed pressure drop. A number of liquid injectivity tests were also carried out. The results reveal that the liquid-phase mobility can increase significantly when the wettability of rocks is altered from strong liquid-wetting to intermediate gas-wetting. All the results show clearly that the application of wettability alteration to intermediate gas-wetting may significantly increase deliverability in gas condensate reservoirs.

  10. WETTABILITY ALTERATION OF POROUS MEDIA TO GAS-WETTING FOR IMPROVING PRODUCTIVITY AND INJECTIVITY IN GAS-LIQUID FLOWS

    SciTech Connect

    Abbas Firoozabadi

    2003-12-01

    Wettability alteration to intermediate gas-wetting in porous media by treatment with FC-759, a fluoropolymer polymer, has been studied experimentally. Berea sandstone was used as the main rock sample in our work and its wettability before and after chemical treatment was studied at various temperatures from 25 to 93 C. We also studied recovery performance for both gas/oil and oil/water systems for Berea sandstone before and after wettability alteration by chemical treatment. Our experimental study shows that chemical treatment with FC-759 can result in: (1) wettability alteration from strong liquid-wetting to stable intermediate gas-wetting at room temperature and at elevated temperatures; (2) neutral wetting for gas, oil, and water phases in two-phase flow; (3) significant increase in oil mobility for gas/oil system; and (4) improved recovery behavior for both gas/oil and oil/water systems. This work reveals a potential for field application for improved gas-well deliverability and well injectivity by altering the rock wettability around wellbore in gas condensate reservoirs from strong liquid-wetting to intermediate gas-wetting.

  11. Capillary Flow of Oil in a Single Foam Microchannel

    NASA Astrophysics Data System (ADS)

    Piroird, Keyvan; Lorenceau, lise

    2013-12-01

    When using appropriate surfactants, oil and aqueous foam can be intimately mixed without the foam being destroyed. In this Letter, we show that a foam, initially free of oil, can draw an oil drop under the action of capillary forces and stretch it through the aqueous network. We focus on the suction of oil by a single horizontal foam channel, known as a Plateau border. In such confined channels, imbibition dynamics are governed by a balance between capillarity and viscosity. Yet, the scaling law for our system differs from that of classical imbibition in porous media such as aqueous foam. This is due to the particular geometry of the liquid channels: Plateau borders filled with foaming solution are always concave whereas they can be convex or flat when filled with oil. Finally, the oil slug, confined in the Plateau border, fragments into droplets following a film breakup.

  12. Pinchoff Structures resulting from Capillary-driven Breakup

    NASA Astrophysics Data System (ADS)

    Steen, P. H.; Chen, Y.-J.

    1997-11-01

    Understanding the way in which a connected volume of fluid becomes disconnected under the action of surface tension is of practical and scientific value. By its very nature, many decades of length scales are probed when a fluid body splits into two or more pieces. The relevance or not of these scales to observed structures depends on the active capillary length scale. A framework for predicting pinchoff structures based on the limiting case of inviscid breakup is presented. The length scale at which the competition between growth of axial and radial curvatures is cut off is key to predicting such structures. This framework is illustrated through the variety of structures observed in the collapse of soap-film bridges.

  13. Wettability patterning for high-rate, pumpless fluid transport on open, non-planar microfluidic platforms.

    PubMed

    Ghosh, Aritra; Ganguly, Ranjan; Schutzius, Thomas M; Megaridis, Constantine M

    2014-05-01

    Surface tension driven transport of liquids on open substrates offers an enabling tool for open micro total analysis systems that are becoming increasingly popular for low-cost biomedical diagnostic devices. The present study uses a facile wettability patterning method to produce open microfluidic tracks that - due to their shape, surface texture and chemistry - are capable of transporting a wide range of liquid volumes (~1-500 ?L) on-chip, overcoming viscous and other opposing forces (e.g., gravity) at the pertinent length scales. Small volumes are handled as individual droplets, while larger volumes require repeated droplet transport. The concept is developed and demonstrated with coatings based on TiO2 filler particles, which, when present in adequate (~80 wt.%) quantities within a hydrophobic fluoroacrylic polymer matrix, form composites that are intrinsically superhydrophobic. Such composite coatings become superhydrophilic upon exposure to UV light (390 nm). A commercial laser printer-based photo-masking approach is used on the coating for spatially selective wettability conversion from superhydrophobic to superhydrophilic. Carefully designed wedge-patterned surface tension confined tracks on the open-air devices move liquid on them without power input, even when acting against gravity. Simple designs of wettability patterning are used on versatile substrates (e.g., metals, polymers, paper) to demonstrate complex droplet handling tasks, e.g., merging, splitting and metered dispensing, some of which occur in 3-D geometries. Fluid transport rates of up to 350 ?L s(-1) are attained. Applicability of the design on metal substrates allows these devices to be used also for other microscale engineering applications, e.g., water management in fuel cells. PMID:24622962

  14. An investigation into a micro-sized droplet impinging on a surface with sharp wettability contrast

    NASA Astrophysics Data System (ADS)

    Lim, C. Y.; Lam, Y. C.

    2014-10-01

    An experimental investigation was conducted into a micro-sized droplet jetted onto a surface with sharp wettability contrast. The dynamics of micro-sized droplet impingement on a sharp wettability contrast surface, which is critical in inkjet printing technology, has not been investigated in the literature. Hydrophilic lines with line widths ranging from 27 to 53 m, and contact angle ranging from 17 to 77, were patterned on a hydrophobic surface with a contact angle of 107. Water droplets with a diameter of 81 m were impinged at various offset distances from the centre of the hydrophilic line. The evolution of the droplet upon impingement can be divided into three distinct phases, namely the kinematic phase, the translating phase where the droplet moves towards the centre of the hydrophilic line, and the conforming phase where the droplet spreads along the line. The key parameters affecting the conformability of the droplet to the hydrophilic line pattern are the ratio of the line width to the initial droplet diameter and the contact angle of the hydrophilic line. The droplet will only conform completely to the hydrophilic pattern if the line width is not overly small relative to the droplet and the contact angle of the hydrophilic line is sufficiently low. The impact offset distance does not affect the final shape and final location of the droplet, as long as part of the droplet touches the hydrophilic line upon impingement. This process has a significant impact on inkjet printing technology as high accuracy of inkjet droplet deposition and shape control can be achieved through wettability patterning.

  15. Extragingival pyogenic granuloma histologically mimicking capillary hemangioma

    PubMed Central

    Dahiya, Ritu; Kathuria, Abhinav

    2014-01-01

    Pyogenic granuloma is a tumor-like proliferation to a non-specific infection. The tumor-like growth is considered to be non-neoplastic in nature and presents in various clinical and histological forms in the oral cavity. Hemangiomas are benign vascular anomalies characterized by benign proliferation of blood vessels. The aim of this article is to drive attention toward the uncommon location of capillary hemangioma on the palate. In spite of their benign nature, intraoral capillary hemangiomas are always clinically important to be diagnosed well in time and suitably managed. The lesion in the present case although clinically diagnosed as pyogenic granuloma gave a histological picture of capillary hemangioma when surgically excised. PMID:25425828

  16. Novel absorption detection techniques for capillary electrophoresis

    SciTech Connect

    Xue, Y.

    1994-07-27

    Capillary electrophoresis (CE) has emerged as one of the most versatile separation methods. However, efficient separation is not sufficient unless coupled to adequate detection. The narrow inner diameter (I.D.) of the capillary column raises a big challenge to detection methods. For UV-vis absorption detection, the concentration sensitivity is only at the {mu}M level. Most commercial CE instruments are equipped with incoherent UV-vis lamps. Low-brightness, instability and inefficient coupling of the light source with the capillary limit the further improvement of UV-vis absorption detection in CE. The goals of this research have been to show the utility of laser-based absorption detection. The approaches involve: on-column double-beam laser absorption detection and its application to the detection of small ions and proteins, and absorption detection with the bubble-shaped flow cell.

  17. Capillary movement of liquid in granular beds

    NASA Technical Reports Server (NTRS)

    Yendler, Boris; Webbon, Bruce

    1993-01-01

    Knowledge of capillary migration of liquids in granular beds in microgravity is essential for the development of a substrate based nutrient delivery sytem for the growth of plants in space. This problem is also interesting from the theoretical as well as the practical point of view. The purpose of this study was to model capillary water propagation through a granular bed in microgravity. In our ground experiments, water propagation is driven primarily by capillary force. Data for spherical partical sizes in the range from 0.46 to 2 mm have been obtained. It was shown that the velocity of water propagation is very sensitive to particle size. Theoretical consideration is also provided. Actual space flight experiments are planned for the future to confirm our results.

  18. Diode array detection in capillary electrophoresis.

    PubMed

    Heiger, D N; Kaltenbach, P; Sievert, H J

    1994-10-01

    Diode array detection (DAD) in capillary electrophoresis (CE) offers similar advantages over single-wavelength detection as it does in high performance liquid chromatography (HPLC). Thus, confirmation of compound identity and establishment of peak purity are critical issues in CE, necessitating sensitive and specific detection. With an optimized optical system, DAD yields sensitivity comparable to that of single or variable wavelength detectors. Sensitivity can be further improved three to five times by use of expanded pathlength capillaries employing the so-called bubble cell. Optimization of optical design, as well as maintenance of spectral fidelity, will be discussed in this work. A variety of applications of CE, and specifically of micellar electrokinetic capillary chromatography (MEKC), with emphasis on quantitative analysis, sensitivity, linearity, spectral identification, and peak purity verification will be presented. The use of spectral information for peak tracking in MEKC method development and for the assessment of purity of electrodistorted peaks will also be illustrated. PMID:7895713

  19. Analysis of glycated hemoglobin A1c by capillary electrophoresis and capillary isoelectric focusing.

    PubMed

    Koval, Duan; Kai?ka, Vclav; Cottet, Herv

    2011-06-01

    Two capillary electrophoretic methods were developed and evaluated for measurement of glycated hemoglobin A1c (HbA1c). First, a capillary electrophoresis analysis is performed with a sodium tetraborate buffer (pH 9.3) as background electrolyte in a neutrally coated capillary. HbA1c is separated from HbA0 due to specific interactions of borate anions with the cis-diol pattern in the saccharide moiety of glycohemoglobin. Second, a capillary isoelectric focusing method, which exploits a difference in pI values of HbA0 and HbA1c, is performed with Servalyt pH 6-8 or alternatively with Biolyte pH 6-8 carrier ampholytes spiked with a narrow pH cut of pH 7.2 prepared by preparative fractionation of Servalyt pH 4-9 carrier ampholytes. Both methods reflect recent developments in the methodology of capillary electrophoresis. They allow quantifying HbA1c in generic capillary electrophoresis analyzer with specificity that is consistent with previously reported electrophoretic assays in slab gels and capillaries. PMID:21300018

  20. Simple relations for wettability of a droplet on a low-surface-energy solid

    SciTech Connect

    Yonemoto, Yukihiro; Kunugi, Tomoaki

    2014-04-11

    A treatment of the contact angle is very difficult because it exhibits a hysteresis such as dynamic contact angle and does not necessarily take a constant value. For understanding such complicated behavior of droplet, simple but fundamental consideration is very important. In the present study, wettability of a binary mixture droplet on low surface energy solid is experimentally and theoretically investigated. A simple theoretical model is applied to the droplet behavior considering a situation before and after touching the solid surface from a view point of thermodynamic surface energy. The model can explain the relationships among the contact angle (θ), surface energy of liquid (σ{sub lg}) and the droplet radius (R)

  1. Self-erasing and rewritable wettability patterns on ZnO thin films

    SciTech Connect

    Kekkonen, Ville; Hakola, Antti; Kajava, Timo; Ras, Robin H. A.; Sahramo, Elina; Malm, Jari; Karppinen, Maarit

    2010-07-26

    Self-erasing patterns allow a substrate to be patterned multiple times or could store temporary information for secret communications, and are mostly based on photochromic molecules to change the color of the pattern. Herein we demonstrate self-erasing patterns of wettability on thin ZnO films made by atomic layer deposition. Hydrophilic patterns are written using UV light and decay spontaneously, i.e. become hydrophobic, or are erased aided by vacuum conditions or heat. We demonstrate that these patterns can be applied for channels to confine flow of water without physical walls.

  2. The effect of surface wettability on water vapor condensation in nanoscale

    NASA Astrophysics Data System (ADS)

    Niu, D.; Tang, G. H.

    2016-01-01

    The effect of surface wettability on condensation heat transfer in a nanochannel is studied with the molecular dynamics simulations. Different from the conventional size, the results show that the filmwise mode leads to more efficient heat transfer than the dropwise mode, which is attributed to a lower interfacial thermal resistance between the hydrophilic surface and the condensed water compared with the hydrophobic case. The observed temperature jump at the solid-liquid surface confirms that the hydrophilic properties of the solid surface can suppress the interfacial thermal resistance and improve the condensation heat transfer performance effectively.

  3. Reversible wettability conversion of electrodeposited graphene oxide/titania nanocomposite coating: Investigation of surface structures

    NASA Astrophysics Data System (ADS)

    Naghdi, Samira; Jaleh, Babak; Shahbazi, Nima

    2016-04-01

    Graphene oxide/titania (GO/TiO2) nanocomposite have been successfully prepared by a simple method and deposited on the surface of aluminum (Al) by the electrophoretic deposition method. The effect of thermal annealing on wettability of GO/TiO2 coating has been investigated. According to the obtained results, the water contact angle (WCA) increased with an increase in annealing temperature which may be attributed to the regulation of coating from superhydrophilic (WCA ≈ 5°) to superhydrophobic (WCA ≈ 148°) via thermal annealing. Moreover, the superhydrophobic coating was changed to a superhydrophilic one by using ultraviolet irradiation and this effect was reversible by heat treatment.

  4. Photo-induced wettability of TiO{sub 2} film with Au buffer layer

    SciTech Connect

    Purkayastha, Debarun Dhar; Sangani, L. D. Varma; Krishna, M. Ghanashyam; Madhurima, V.

    2014-04-24

    The effect of thickness of Au buffer layer (15-25 nm) between TiO{sub 2} film and substrate on the wettability of TiO{sub 2} films is reported. TiO{sub 2} films grown on Au buffer layer have a higher contact angle of 96-;100° as compared to 47.6o for the film grown without buffer layer. The transition from hydrophobicity to hydrophilicity under UV irradiation occurs within 10 min. for the buffer layered films whereas it is almost 30 min. for the film grown without buffer layer. The enhanced photo induced hydrophilicity is shown to be surface energy driven.

  5. Simple relations for wettability of a droplet on a low-surface-energy solid

    NASA Astrophysics Data System (ADS)

    Yonemoto, Yukihiro; Kunugi, Tomoaki

    2014-04-01

    A treatment of the contact angle is very difficult because it exhibits a hysteresis such as dynamic contact angle and does not necessarily take a constant value. For understanding such complicated behavior of droplet, simple but fundamental consideration is very important. In the present study, wettability of a binary mixture droplet on low surface energy solid is experimentally and theoretically investigated. A simple theoretical model is applied to the droplet behavior considering a situation before and after touching the solid surface from a view point of thermodynamic surface energy. The model can explain the relationships among the contact angle (?), surface energy of liquid (?lg) and the droplet radius (R).

  6. The effect of surface wettability on water vapor condensation in nanoscale.

    PubMed

    Niu, D; Tang, G H

    2016-01-01

    The effect of surface wettability on condensation heat transfer in a nanochannel is studied with the molecular dynamics simulations. Different from the conventional size, the results show that the filmwise mode leads to more efficient heat transfer than the dropwise mode, which is attributed to a lower interfacial thermal resistance between the hydrophilic surface and the condensed water compared with the hydrophobic case. The observed temperature jump at the solid-liquid surface confirms that the hydrophilic properties of the solid surface can suppress the interfacial thermal resistance and improve the condensation heat transfer performance effectively. PMID:26754316

  7. The effect of surface wettability on water vapor condensation in nanoscale

    PubMed Central

    Niu, D.; Tang, G. H.

    2016-01-01

    The effect of surface wettability on condensation heat transfer in a nanochannel is studied with the molecular dynamics simulations. Different from the conventional size, the results show that the filmwise mode leads to more efficient heat transfer than the dropwise mode, which is attributed to a lower interfacial thermal resistance between the hydrophilic surface and the condensed water compared with the hydrophobic case. The observed temperature jump at the solid-liquid surface confirms that the hydrophilic properties of the solid surface can suppress the interfacial thermal resistance and improve the condensation heat transfer performance effectively. PMID:26754316

  8. Mach-like capillary-gravity wakes.

    PubMed

    Moisy, Frdric; Rabaud, Marc

    2014-08-01

    We determine experimentally the angle ? of maximum wave amplitude in the far-field wake behind a vertical surface-piercing cylinder translated at constant velocity U for Bond numbers Bo(D)=D/?(c) ranging between 0.1 and 4.2, where D is the cylinder diameter and ?(c) the capillary length. In all cases the wake angle is found to follow a Mach-like law at large velocity, ??U(-1), but with different prefactors depending on the value of Bo(D). For small Bo(D) (large capillary effects), the wake angle approximately follows the law ??c(g,min)/U, where c(g,min) is the minimum group velocity of capillary-gravity waves. For larger Bo(D) (weak capillary effects), we recover a law ???[gD]/U similar to that found for ship wakes at large velocity [Rabaud and Moisy, Phys. Rev. Lett. 110, 214503 (2013)]. Using the general property of dispersive waves that the characteristic wavelength of the wave packet emitted by a disturbance is of order of the disturbance size, we propose a simple model that describes the transition between these two Mach-like regimes as the Bond number is varied. We show that the new capillary law ??c(g,min)/U originates from the presence of a capillary cusp angle (distinct from the usual gravity cusp angle), along which the energy radiated by the disturbance accumulates for Bond numbers of order of unity. This model, complemented by numerical simulations of the surface elevation induced by a moving Gaussian pressure disturbance, is in qualitative agreement with experimental measurements. PMID:25215822

  9. Mach-like capillary-gravity wakes

    NASA Astrophysics Data System (ADS)

    Moisy, Frdric; Rabaud, Marc

    2014-08-01

    We determine experimentally the angle ? of maximum wave amplitude in the far-field wake behind a vertical surface-piercing cylinder translated at constant velocity U for Bond numbers BoD=D/?c ranging between 0.1 and 4.2, where D is the cylinder diameter and ?c the capillary length. In all cases the wake angle is found to follow a Mach-like law at large velocity, ? U-1, but with different prefactors depending on the value of BoD. For small BoD (large capillary effects), the wake angle approximately follows the law ? ?cg ,min/U, where cg ,min is the minimum group velocity of capillary-gravity waves. For larger BoD (weak capillary effects), we recover a law ? ?gD /U similar to that found for ship wakes at large velocity [Rabaud and Moisy, Phys. Rev. Lett. 110, 214503 (2013), 10.1103/PhysRevLett.110.214503]. Using the general property of dispersive waves that the characteristic wavelength of the wave packet emitted by a disturbance is of order of the disturbance size, we propose a simple model that describes the transition between these two Mach-like regimes as the Bond number is varied. We show that the new capillary law ? ?cg ,min/U originates from the presence of a capillary cusp angle (distinct from the usual gravity cusp angle), along which the energy radiated by the disturbance accumulates for Bond numbers of order of unity. This model, complemented by numerical simulations of the surface elevation induced by a moving Gaussian pressure disturbance, is in qualitative agreement with experimental measurements.

  10. Capillary Penetration into Inclined Circular Glass Tubes.

    PubMed

    Trabi, Christophe L; Ouali, F Fouzia; McHale, Glen; Javed, Haadi; Morris, Robert H; Newton, Michael I

    2016-02-01

    The spontaneous penetration of a wetting liquid into a vertical tube against the force of gravity and the imbibition of the same liquid into a horizontal tube (or channel) are both driven by capillary forces and described by the same fundamental equations. However, there have been few experimental studies of the transition from one orientation to the other. We report systematic measurements of capillary penetration of polydimethylsiloxane oils of viscosities 9.6, 19.2, and 48.0 mPas into glass capillary tubes. We first report the effect of tube radii R between 140 and 675 ?m on the dynamics of spontaneous imbibition. We show that the data can be fitted using the exact numerical solution to the governing equations and that these are similar to fits using the analytical viscogravitational approximation. However, larger diameter tubes show a rate of penetration slower than expected using an equilibrium contact angle and the known value of liquid viscosity. To account for the slowness, an increase in viscosity by a factor (?/?)scaling is needed. We show full agreement with theory requires the ratio R/?(-1) ? 0.1 or less, where ?(-1) is the capillary length. In addition, we propose an experimental method that enables the determination of the dynamic contact angle during imbibition, which gives values that agree with the literature values. We then report measurements of dynamic penetration into the tubes of R = 190 and 650 ?m for a range of inclination angles to the horizontal, ?, from 5 to 90. We show that capillary penetration can still be fitted using the viscogravitational solution, rather than the Bosanquet solution which describes imbibition without gravity, even for inclination angles as low as 10. Moreover, at these low angles, the effect of the tube radius is found to diminish and this appears to relate to an effective capillary length, ?(-1)(?) = (?LV/?g sin ?)(1/2). PMID:26738739

  11. Spatiotemporal instability of a confined capillary jet.

    PubMed

    Herrada, M A; Gañán-Calvo, A M; Guillot, P

    2008-10-01

    Recent experimental studies on the instability of capillary jets have revealed the suitability of a linear spatiotemporal instability analysis to ascertain the parametrical conditions for specific flow regimes such as steady jetting or dripping. In this work, an extensive analytical, numerical, and experimental description of confined capillary jets is provided, leading to an integrated picture both in terms of data and interpretation. We propose an extended, accurate analytic model in the low Reynolds number limit, and introduce a numerical scheme to predict the system response when the liquid inertia is not negligible. Theoretical predictions show remarkable accuracy when compared with the extensive experimental mapping. PMID:18999531

  12. Use of Plastic Capillaries for Macromolecular Crystallization

    NASA Technical Reports Server (NTRS)

    Potter, Rachel R.; Hong, Young-Soo; Ciszak, Ewa M.

    2003-01-01

    Methods of crystallization of biomolecules in plastic capillaries (Nalgene 870 PFA tubing) are presented. These crystallization methods used batch, free-interface liquid- liquid diffusion alone, or a combination with vapor diffusion. Results demonstrated growth of crystals of test proteins such as thaumatin and glucose isomerase, as well as protein studied in our laboratory such dihydrolipoamide dehydrogenase. Once the solutions were loaded in capillaries, they were stored in the tubes in frozen state at cryogenic temperatures until the desired time of activation of crystallization experiments.

  13. Control of electroosmosis in coated quartz capillaries

    NASA Technical Reports Server (NTRS)

    Herren, Blair J.; Van Alstine, James; Snyder, Robert S.; Shafer, Steven G.; Harris, J. Milton

    1987-01-01

    The effectiveness of various coatings for controlling the electroosmotic fluid flow that hinders electrophoretic processes is studied using analytical particle microelectrophoresis. The mobilities of 2-micron diameter glass and polystyrene latex spheres (exhibiting both negative and zero effective surface charge) were measured in 2-mm diameter quartz capillaries filled with NaCl solutions within the 3.5-7.8 pH range. It is found that capillary inner surface coatings using 5000 molecular weight (or higher) poly(ethylene glycol): significantly reduced electroosmosis within the selected pH range, were stable for long time periods, and appeared to be more effective than dextran, methylcellulose, or silane coatings.

  14. Lobular capillary hemangioma of the trachea.

    PubMed

    Xu, Qingqing; Yin, Xindao; Sutedjo, Janesya; Sun, Jun; Jiang, Liang; Lu, Lingquan

    2015-02-01

    As a polypoid form of capillary hemangioma, lobular capillary hemangioma (LCH) most commonly occurs on the cutaneous and mucosal surfaces and is frequently benign in children. Tracheal LCH is a rare benign tumor in adults, with hemoptysis being one of the most serious forms of presentation. A definite diagnosis of LCH depends on its histopathology. In clinical practice, however, radiological characteristics are an important component for making a suggestive diagnosis. We present a case of tracheal LCH and describe its features on computed tomography, pathology, and differential diagnosis. A review of the relevant literature is also provided. PMID:25644803

  15. Pharmaceutical analysis using micellar electrokinetic capillary chromatography.

    PubMed

    Swaile, D F; Burton, D E; Balchunas, A T; Sepaniak, M J

    1988-08-01

    The potential utility in pharmaceutical analysis of a capillary electrokinetic separation technique that employs a micellar "pseudo-stationary phase" is discussed and illustrated. Chromatograms of separations of vitamin metabolites and derivatized amino acids are presented to illustrate the high efficiency of the technique and the ability to simultaneously separate the charged and neutral components of pharmaceutical samples. The analytical characteristics of the technique and the importance of optimizing experimental parameters, such as surfactant concentration and capillary column diameter, are discussed and demonstrated with the aid of chromatograms. PMID:3215989

  16. Biological Application of Capillary Discharge in Water

    NASA Astrophysics Data System (ADS)

    Guan, Weimin; Ihara, Satoshi; Satoh, Saburoh; Yamabe, Chobei

    This paper presents a capillary discharge in water, which was applied to sterilize tiny apertures of medical equipments due to the penetration of dissolved sterilization agent in water. In order to obtain stable and energetic discharge for sterilization, a capillary dielectric tube was used as a barrier material. Discharges in the tube can generate high electrical fields, ultraviolet rays, as well as various chemically active species which can be utilized for sterilization and decomposition of toxins and bacteria in water. The sterilization results of Escherichia coli (E. coli) were successful after 1 hour of treatment.

  17. DEVELOPMENT OF A CAPILLARY WICK UNSATURATED ZONE PORE WATER SAMPLER

    EPA Science Inventory

    Existing unsaturated zone soil water samplers have several deficiencies which jeopardize their utility for field sampling. A capillary wick sampler was developed to overcome these problems. Materials for its construction were selected and tested for conductivity, capillary rise, ...

  18. Effects of Er: YAG laser irradiation on wettability, surface roughness, and biocompatibility of SLA titanium surfaces: an in vitro study.

    PubMed

    Ayobian-Markazi, Nader; Karimi, Mohammadreza; Safar-Hajhosseini, Ali

    2015-02-01

    The erbium: yttrium-aluminum-garnet (Er: YAG) laser has been introduced as an effective method in the decontamination of implant surfaces. Data concerning the effects of the Er: YAG laser on the biological and surface properties of titanium are conflicting. Cellular behavior is greatly affected by surface properties, including composition, roughness, wettability, and morphology of the titanium surface. The aim of this study was to investigate the influence of the Er: YAG laser on the biocompatibility, surface roughness, and wettability of sandblasted and acid-etched (SLA) titanium surfaces. Twenty-one SLA titanium disks were irradiated by the Er: YAG laser at a pulse energy of 100mJ, with a pulse frequency of 10Hz under water irrigation for 1min. Cell viability, surface roughness, and wettability alterations were evaluated. Thirteen nonirradiated SLA disks were used as the control groups. Human osteoblast-like SaOs-2 cells were seeded onto the disks in culture media. Cell viability was evaluated using the methylthiazol tetrazolium assay. The surface roughness and wettability of the test and control groups were measured using profilometer and tensiometer devices, respectively. A significantly higher cell viability rate was observed in the test group (p?=?0.032). The surface roughness was significantly reduced in the test group compared with the control group (p?=?0.008). The surface wettability was significantly higher in the test group (p?=?0.004). Within the limits of this study, the application of the Er: YAG laser with the previously described properties did not appear to have adverse effects on the biocompatibility of the SLA titanium surfaces. Application of this laser decreased the surface roughness and increased the wettability of the SLA titanium surfaces. PMID:23760881

  19. Integrated, Multi-Scale Characterization of Imbibition and Wettability Phenomena Using Magnetic Resonance and Wide-Band Dielectric Measurements

    SciTech Connect

    Mukul M. Sharma; Steven L. Bryant; Carlos Torres-Verdin; George Hirasaki

    2007-09-30

    The petrophysical properties of rocks, particularly their relative permeability and wettability, strongly influence the efficiency and the time-scale of all hydrocarbon recovery processes. However, the quantitative relationships needed to account for the influence of wettability and pore structure on multi-phase flow are not yet available, largely due to the complexity of the phenomena controlling wettability and the difficulty of characterizing rock properties at the relevant length scales. This project brings together several advanced technologies to characterize pore structure and wettability. Grain-scale models are developed that help to better interpret the electric and dielectric response of rocks. These studies allow the computation of realistic configurations of two immiscible fluids as a function of wettability and geologic characteristics. These fluid configurations form a basis for predicting and explaining macroscopic behavior, including the relationship between relative permeability, wettability and laboratory and wireline log measurements of NMR and dielectric response. Dielectric and NMR measurements have been made show that the response of the rocks depends on the wetting and flow properties of the rock. The theoretical models can be used for a better interpretation and inversion of standard well logs to obtain accurate and reliable estimates of fluid saturation and of their producibility. The ultimate benefit of this combined theoretical/empirical approach for reservoir characterization is that rather than reproducing the behavior of any particular sample or set of samples, it can explain and predict trends in behavior that can be applied at a range of length scales, including correlation with wireline logs, seismic, and geologic units and strata. This approach can substantially enhance wireline log interpretation for reservoir characterization and provide better descriptions, at several scales, of crucial reservoir flow properties that govern oil recovery.

  20. Spectrometer capillary vessel and method of making same

    DOEpatents

    Linehan, J.C.; Yonker, C.R.; Zemanian, T.S.; Franz, J.A.

    1995-11-21

    The present invention is an arrangement of a glass capillary tube for use in spectroscopy. In particular, the invention is a capillary arranged in a manner permitting a plurality or multiplicity of passes of a sample material through a spectroscopic measurement zone. In a preferred embodiment, the multi-pass capillary is insertable within a standard NMR sample tube. The present invention further includes a method of making the multi-pass capillary tube and an apparatus for spinning the tube. 13 figs.