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1

Exploring Capillary Action  

NSDL National Science Digital Library

Students observe multiple examples of capillary action. First they observe the shape of a glass-water meniscus and explain its shape in terms of the adhesive attraction of the water to the glass. Then they study capillary tubes and observe water climbing due to capillary action in the glass tubes. Finally, students experience a real-world application of capillary action by designing and using "capillary siphons" to filter water.

NSF CAREER Award and RET Program, Mechanical Engineering and Material Science,

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

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.

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

2006-02-01

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

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.

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

2006-06-08

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

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.

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

2006-12-08

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

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.

Norman R. Morrow

2004-05-01

6

Capillary, wettability and interfacial dynamics in polymer electrolyte fuel cells  

SciTech Connect

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.

Mukherjee, Partha P [Los Alamos National Laboratory

2009-01-01

7

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

NASA Astrophysics Data System (ADS)

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 ( ?CRM; liquid penetration into a 3-d system), the Wilhelmy plate method ( ?WPM; measurement of capillary forces acting on a plane sample) and the Sessile Drop Method ( ?SDM; optical CA analysis of drop contour on a plane sample). Results were compared with the CAs calculated from capillary rise in long vertical columns ( ?ECR), 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 ( ?EWPM), as well as the Sessile Drop CA, ?SDM, were close to the ones of ?ECR. We concluded that ?EWPM and ?SDM 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.

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

2010-03-01

8

Moving On Up: Capillary Action II  

NSDL National Science Digital Library

Learners explore capillary action in plants (such as plants ability to move water from roots to leaves) in an investigation called Paper Blooms. Placing paper flowers in water mixed with food coloring, learners observe how water moves through a flower. Students can then try the activity using different fluids such as soapy water or salty water. In the investigation Toothpick Tricks learners observe slightly different capillary action in simple models of flowers made with toothpicks.

2013-12-18

9

Moving On Up: Capillary Action 1  

NSDL National Science Digital Library

Over the course of several days, learners explore the property of water that helps plants move water from roots to leaves or gives paper towels the capacity to soak up water. Learners will observe water's ability to move through narrow tube-like spaces known as capillaries, in an investigation called Colorizing Carnations. Learners then modify the variables in their activity to test how capillary action is affected by soapy water, salty water, different liquids and/or different plants.

2013-12-18

10

AA Parametric Model for Predicting Relative Permeability-Saturation-Capillary Pressure Relationships of Oil?Water Systems in Porous Media with Mixed Wettability  

SciTech Connect

A parametric two-phase, oil-water relative permeability/capillary pressure model for petroleum engineering and environmental applications is developed for porous media in which the smaller pores are strongly water-wet and the larger pores tend to be intermediate- or oil-wet. A saturation index, which can vary from 0 to 1, is used to distinguish those pores that are strongly water-wet from those that have intermediate- or oil-wet characteristics. The capillary pressure submodel is capable of describing main-drainage and hysteretic saturation-path saturations for positive and negative oil-water capillary pressures. At high oil-water capillary pressures, an asymptote is approached as the water saturation approaches the residual water saturation. At low oil-water capillary pressures (i.e., negative), another asymptote is approached as the oil saturation approaches the residual oil saturation. Hysteresis in capillary pressure relations, including water entrapment, is modeled. Relative permeabilities are predicted using parameters that describe main drainage capillary pressure relations and accounting for how water and oil are distributed throughout the pore spaces of a porous medium with mixed wettability. The capillary pressure submodel is tested against published experimental data, and an example of how to use the relative permeability/capillary pressure model for a hypothetical saturation-path scenario involving several imbibition and drainage paths is given. Features of the model are also explained. Results suggest that the proposed model is capable of predicting relative permeability/capillary pressure characteristics of porous media mixed wettability.

Lenhard, Robert J.(INEEL) [INEEL; Oostrom, Mart (BATTELLE (PACIFIC NW LAB)) [BATTELLE (PACIFIC NW LAB)

1998-01-01

11

Capillary pressure-saturation relations in porous media including the effect of wettability  

Microsoft Academic Search

In this work a functional relationship between capillary pressure and wetting phase saturation has been developed. Both the imbibition and drainage of a wetting phase liquid into a porous medium consisting of clean unconsolidated silica particles have been considered. In all, two bead packings, with average particle diameters of 120 ?m and 360 ?m, and three liquids—water, ethanol, and refrigerant-113—were

William A. Moseleya; Vijay K. Dhir

1996-01-01

12

Fractional wettability effects on two-and three-fluid capillary pressure-saturation relations  

Microsoft Academic Search

Studies of the relation between capillary pressure (Pc) and fluid saturation (S) for porous media containing oil-water or air-oil-water, often assume that the medium is strongly water-wet. Natural porous media, however, are composed of a variety of mineral constituents; such media are typically composed of water- and oil-wet fractions. This study reports on two- and three-fluid Pc-S data for media

Scott A. Bradford; Feike J. Leij

1995-01-01

13

The effects of wettability and trapping on relationships between interfacial area, capillary pressure and saturation in porous media: A pore-scale network modeling approach  

NASA Astrophysics Data System (ADS)

SummaryWe use a three-dimensional mixed-wet random pore-scale network model to investigate the impact of wettability and trapping on the relationship between interfacial area, capillary pressure and saturation in two-phase drainage and imbibition processes. The model is a three-dimensional network of interconnected pores and throats of various geometrical shapes. It allows multiple phases to be present in each capillary element in wetting and spreading layers, as well as occupying the center of the pore space. Two different random networks that represent the pore space in Berea and a Saudi Arabia reservoir sandstone are used in this study. We allow the wettability of the rock surfaces contacted by oil to alter after primary drainage. The model takes into account both contact angle and trapping hystereses. We model primary oil drainage and water flooding for mixed-wet conditions, and secondary oil injection for a water-wet system. The total interfacial area for pores and throats are calculated when the system is at capillary equilibrium. They include contributions from the arc menisci (AMs) between the bulk and corner fluids, and from the main terminal menisci (MTMs) between different bulk fluids. We investigate hysteresis in these relationships by performing water injection into systems of varying wettability and initial water saturation. We show that trapping and contact angle hystereses significantly affect the interfacial area. In a strongly water-wet system, a sharp increase is observed at the beginning of water flood, which shifts the area to a higher level than primary drainage. As we change the wettability of the system from strongly water-wet to strongly oil-wet, the trapped oil saturation decreases significantly. Starting water flood from intermediate water saturations, greater than the irreducible water saturation, can also affect the non-wetting phase entrapment, resulting in different interfacial area behaviors. This can increase the interfacial area significantly in oil-wet systems. A qualitative comparison of our results with the experimental data available in literature for glass beads shows, with some expected differences, an encouraging agreement. Also, our results agree well with those generated by the previously developed models.

Raeesi, Behrooz; Piri, Mohammad

2009-10-01

14

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

Microsoft Academic Search

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

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

2003-01-01

15

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

PubMed

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

Hammond, Paul S; Unsal, Evren

2011-04-19

16

Algorithms in Series Form for the Calculation of Capillary Action in Cylindrical Tubes  

Microsoft Academic Search

Algorithms in series form are derived, suitable for computer calculation of capillary action in vertical cylindrical tubes. Concerning the capillary depression of mercury barometers and manometers they are shown to give, in the entire range of practical interest, results at least as accurate as tables based on numerical integration. They have, however, far more general application, since with their help

J. F. Ury

1969-01-01

17

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

NASA Astrophysics Data System (ADS)

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 36°C 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 36°C), point towards a wettability alteration of the Bentheimer sandstone upon contact with supercritical CO2.

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

2013-12-01

18

Simulation of Oil Displacement from Oil-Wet Cores by Interfacial Tension Reduction and Wettability Alteration  

E-print Network

wettability toward water-wet may increase spontaneous imbibition of water. This change in rock wettability leads to positive capillary pressure and results in higher brine counter-current imbibition and therefore a higher oil production rate. A three...

Kalaei, Mohammad Hosein

2010-01-29

19

Capillary Action may be used in feeding Particles and as calorimeters in Accelerators  

NASA Astrophysics Data System (ADS)

Capillary Action was first proposed to be a Quantum Mechanical Effect by this Author. In plants it takes no work for water to travel up a tree, a flow of fluid begins when a thermal photon causes the water at the top of the column to evaporate. When the molecule evaporates a ``hole'' is transfered down the water column to the roots where apparently the ``hole'' establishes a ``current'' of ``holes'' in the manner of theory which is superior to the theory of ``solid-state'' physics. The ``hole'' can also be used in a ``path-integral'' formulation as is done in particle physics. A particle (a thermal photon) would strike the surface at the top of the column in through some ``spring'' method cause the whole column to rise--which is an interesting variation of the ``spring-in-mattress'' model used in Quantum Field Theory. Obviously a proper size tube- say a nanotube could be coupled to an Accelerator and the Quantum Field Theory Calculation of the Beam could be used to couple with the ``spring'' field available in the Tube. For the right sized tube, a Calorimeter would be the result. For other sized tubes, the beam could be fed with molecules and particles that have similar characteristics to water. Capillary Action is an example of Particle Physics seen in directly in the Classical world.

Kriske, Richard

2012-11-01

20

Surface wettability of macroporous anodized aluminum oxide.  

PubMed

The correlation between the structural characteristics and the wetting of anodized aluminum oxide (AAO) surfaces with large pore sizes (>100 nm) is discussed. The roughness-induced wettability is systematically examined for oxide films grown by a two-step, high-field anodization in phosphoric acid of three different concentrations using a commercial aluminum alloy. This is done for the as-synthesized AAO layers, after various degrees of pore widening by a wet chemical etching in phosphoric acid solution, and upon surface modification by either Lauric acid or a silane. The as-grown AAO films feature structurally disordered pore architectures with average pore openings in the range 140-190 nm but with similar interpore distances of about 405 nm. The formation of such AAO structures induces a transition from slightly hydrophilic to moderately hydrophobic surfaces up to film thicknesses of about 6 ?m. Increased hydrophobicity is obtained by pore opening and a maximum value of the water contact angle (WCA) of about 128° is measured for AAO arrays with a surface porosity close to 60%. Higher surface porosity by prolonged wet chemical etching leads to a rapid decrease in the WCA as a result of the limited pore wall thickness and partial collapse of the dead-end pore structures. Modification of the AAO surfaces by Lauric acid results in 5-30° higher WCA's, whereas near-superhydrophobicity (WCA ~146°) is realized through silane coating. The "rose petal effect" of strongly hydrophobic wetting with high adhesive force on the produced AAO surfaces is explained by a partial penetration of water through capillary action into the dead-end pore cavities which leads to a wetting state in-between the Wenzel and Cassie states. Moreover, practical guidelines for the synthesis of rough, highly porous AAO structures with controlled wettability are provided and the possibility of forming superhydrophobic surfaces is evaluated. PMID:23506401

Buijnsters, Josephus G; Zhong, Rui; Tsyntsaru, Natalia; Celis, Jean-Pierre

2013-04-24

21

Thin films, asphaltenes, and reservoir wettability  

SciTech Connect

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.

Kaminsky, R.; Bergeron, V.; Radke, C.J. [Lawrence Berkeley Lab., CA (United States)]|[California Univ., Berkeley, CA (United States). Dept. of Chemical Engineering

1993-04-01

22

Wettability of graphene.  

PubMed

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

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

2013-04-10

23

Analysis of endoproteinase Arg C action on adrenocorticotrophic hormone by capillary electrophoresis and reversed-phase high-performance liquid chromatography.  

PubMed

The specificity and rate of cleavage of adrenocorticotrophic hormone (ACTH) peptide bonds by endoproteinase Arg C were analyzed using capillary electrophoresis (CE) and reversed-phase (C18) high-performance liquid chromatography (HPLC). Acidic cleavage products were readily resolved by CE in uncoated capillaries using low ionic strength electrolytes. However, products predicted to have a net positive charge greater than 2 or more than 4 positively charged groups per peptide did not migrate out from the capillary at low ionic strength. Addition of salts and zwitterions to the electrolyte decreased capillary-peptide interactions such that all of the ACTH peptides examined were eluted with high efficiency separation by CE. Commercially obtained endoproteinase Arg C preparations exhibited peptidase activity at Lys-15-Lys16 and at Lys16-Arg17 in addition to the expected cleavage at Arg-X bonds. ACTH peptide bond cleavage rates for Arg8-Trp9, Arg17-Arg-18, Lys15-Lys16, and Lys16-Arg17 were 1.46, 0.096, 0.57, and 0.029 mumol min-1 mg-1 respectively. CE separations generally exhibited better resolution and were accomplished in shorter times than C18 HPLC separations. These properties make CE a particularly appropriate method for kinetic analysis of proteolytic enzyme action on peptide substrates. PMID:1652592

Krueger, R J; Hobbs, T R; Mihal, K A; Tehrani, J; Zeece, M G

1991-05-10

24

Enhancing dropwise condensation through bioinspired wettability patterning.  

PubMed

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

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

2014-11-01

25

Capillary sample  

MedlinePLUS

... in the diagnosis of medical conditions. Capillary blood sampling offers several advantages over drawing blood from a ... sugar several times a day using capillary blood sampling. Disadvantages to capillary blood sampling include: Only a ...

26

Wettability Modification of Nanomaterials by Low-Energy Electron Flux  

PubMed Central

Controllable modification of surface free energy and related properties (wettability, hygroscopicity, agglomeration, etc.) of powders allows both understanding of fine physical mechanism acting on nanoparticle surfaces and improvement of their key characteristics in a number of nanotechnology applications. In this work, we report on the method we developed for electron-induced surface energy and modification of basic, related properties of powders of quite different physical origins such as diamond and ZnO. The applied technique has afforded gradual tuning of the surface free energy, resulting in a wide range of wettability modulation. In ZnO nanomaterial, the wettability has been strongly modified, while for the diamond particles identical electron treatment leads to a weak variation of the same property. Detailed investigation into electron-modified wettability properties has been performed by the use of capillary rise method using a few probing liquids. Basic thermodynamic approaches have been applied to calculations of components of solid–liquid interaction energy. We show that defect-free, low-energy electron treatment technique strongly varies elementary interface interactions and may be used for the development of new technology in the field of nanomaterials. PMID:20596284

2009-01-01

27

Evaluation of Reservoir Wettability and its Effect on Oil Recovery  

SciTech Connect

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.

Buckley, Jill S.

1999-07-01

28

Metallic surfaces with special wettability.  

PubMed

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

Liu, Kesong; Jiang, Lei

2011-03-01

29

Microvalve actuation with wettability conversion through darkness/UV application  

NASA Astrophysics Data System (ADS)

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.

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

2011-02-01

30

Drop impact and wettability: From hydrophilic to superhydrophobic surfaces  

NASA Astrophysics Data System (ADS)

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.

Antonini, Carlo; Amirfazli, Alidad; Marengo, Marco

2012-10-01

31

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

PubMed

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

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

2015-04-01

32

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

SciTech Connect

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.

Hu, W.

1993-09-01

33

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

SciTech Connect

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.

Hu, Weibai

1993-12-31

34

The effect of wettability on capillary pressure and oil recovery  

E-print Network

and residual oil saturation after waterflood in a reservoir. Cleaned cores, which are extracted with strong solvents followed by drying in an oven, have pore surfaces that are strongly wet by water and should be used only for porosity and/or permeability... on the following pages follow the style of the Journal of Petroleum Technology. which are extracted with strong solvents and dried in the oven. This normal cleaning procedure for the cores renders the wettabil- ity of the pore surfaces to be strongly wet...

Chon, Bohyun

1987-01-01

35

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

SciTech Connect

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).

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

1992-09-01

36

Tunable wettability of microstructured polypyrrole films  

E-print Network

This thesis presents the development of the conducting polymer polypyrrole as a viable material for applications requiring switchable wettability. A fabrication procedure that produces robust microstructured polypyrrole ...

Chang, Jean H

2010-01-01

37

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

NASA Astrophysics Data System (ADS)

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.

Chen, Longquan; Bonaccurso, Elmar

2014-08-01

38

Photocontrolled wettability changes in polymer microchannels doped with photochromic molecules  

NASA Astrophysics Data System (ADS)

The authors demonstrate the possibility to control the fluid flow inside microfluidic networks by photoresponsive capillaries. The approach relies on the use of photochromic molecules undergoing reversible changes in their polarity when irradiated with light of specific wavelength, thus varying the wettability of cyclic olefin copolymer microchannels. The realized photoresponsive elements exhibit a decrease up to 20° between the water contact angles of the native and the irradiated surfaces, which could be exploited for enhancing the penetration flow rate of fluids inside microfluidic channels up to 25%. The photocontrollable microfluidic circuitry presents on-off valve behavior, allowing or blocking liquid filling processes on the base of optical control, thus allowing one to manipulate liquid flow within microfluidic networks without mechanical actuation parts.

Caprioli, Lucia; Mele, Elisa; Angilè, Francesco Elio; Girardo, Salvatore; Athanassiou, Athanassia; Camposeo, Andrea; Cingolani, Roberto; Pisignano, Dario

2007-09-01

39

Capillary Hemangioma  

MedlinePLUS

... called the conjunctiva, and the eye socket or orbit. Why do capillary hemangiomas on the eyelids cause ... socket (the area around the eye called the orbit) can put pressure on the eye and result ...

40

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

SciTech Connect

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.

Hu, Weibai

1993-12-01

41

High-throughput screening using the differential radial capillary action of ligand assay identifies ebselen as an inhibitor of diguanylate cyclases.  

PubMed

The rise of bacterial resistance to traditional antibiotics has motivated recent efforts to identify new drug candidates that target virulence factors or their regulatory pathways. One such antivirulence target is the cyclic-di-GMP (cdiGMP) signaling pathway, which regulates biofilm formation, motility, and pathogenesis. Pseudomonas aeruginosa is an important opportunistic pathogen that utilizes cdiGMP-regulated polysaccharides, including alginate and pellicle polysaccharide (PEL), to mediate virulence and antibiotic resistance. CdiGMP activates PEL and alginate biosynthesis by binding to specific receptors including PelD and Alg44. Mutations that abrogate cdiGMP binding to these receptors prevent polysaccharide production. Identification of small molecules that can inhibit cdiGMP binding to the allosteric sites on these proteins could mimic binding defective mutants and potentially reduce biofilm formation or alginate secretion. Here, we report the development of a rapid and quantitative high-throughput screen for inhibitors of protein-cdiGMP interactions based on the differential radial capillary action of ligand assay (DRaCALA). Using this approach, we identified ebselen as an inhibitor of cdiGMP binding to receptors containing an RxxD domain including PelD and diguanylate cyclases (DGC). Ebselen reduces diguanylate cyclase activity by covalently modifying cysteine residues. Ebselen oxide, the selenone analogue of ebselen, also inhibits cdiGMP binding through the same covalent mechanism. Ebselen and ebselen oxide inhibit cdiGMP regulation of biofilm formation and flagella-mediated motility in P. aeruginosa through inhibition of diguanylate cyclases. The identification of ebselen provides a proof-of-principle that a DRaCALA high-throughput screening approach can be used to identify bioactive agents that reverse regulation of cdiGMP signaling by targeting cdiGMP-binding domains. PMID:24134695

Lieberman, Ori J; Orr, Mona W; Wang, Yan; Lee, Vincent T

2014-01-17

42

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

NASA Technical Reports Server (NTRS)

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.

Asthana, R.; Rohatgi, P. K.

1993-01-01

43

Wettability of azobenzene self-assembled monolayers.  

PubMed

The wettability properties of azobenzene self-assembled monolayers (SAMs), in the trans and cis forms, are investigated herein by classical Molecular Dynamics simulations of validated assembly structures described with a dedicated force field. The two different methodologies used for the calculation of the contact angle, one based on the Young's equation and the other on geometrical models, have provided a consistent description of the SAMs wettability in line with available experimental results. Furthermore, we provide an atomistic description of the first layers of water molecules at the solvent-SAM interface, which rationalizes the wettability difference between the cis- and trans-SAMs. PMID:24673397

Pipolo, Silvio; Corni, Stefano

2014-04-22

44

Impact of surfactant-induced wettability alterations on DNAPL invasion in quartz and iron oxide-coated sand systems.  

PubMed

Dense non-aqueous phase liquids (DNAPLs) present in the subsurface may contain surface active compounds that impact DNAPL migration and distribution. While a number of studies have revealed the role surface active compounds play in altering the wettability of quartz sand, few have considered the implications for other minerals common to contaminated sites. This study extends understanding of DNAPL/surfactant wettability to iron oxide surfaces. Specifically, quartz and iron oxide-coated sands in a tetrachloroethene (PCE)/water system containing the organic base (an organic molecule that acts as a base) dodecylamine (DDA) were compared at a variety of scales. Wettability of the minerals' surfaces, and the impact of wettability on capillary resistance to DNAPL entry, were assessed as a function of pH through: (i) advancing and receding contact angles, (ii) primary drainage capillary pressure-saturation experiments, and (iii) small, two-dimensional, flow cell experiments. The work revealed that, at neutral pH and under identical boundary capillary pressures, DNAPL invaded quartz sand but not iron oxide-coated sand; however, at low pH, DNAPL invaded both sands equally. These differences were demonstrated to be due to wettability alterations associated with the strength of attractive forces between DDA and the mineral surface, dictated by the isolectric point of the minerals and system pH. Observed differences in DNAPL invasion behavior were consistent with measured intrinsic contact angles and P(c)-S relationships, the latter requiring scaling by the operative contact angle inside the porous medium for a meaningful comparison. This study suggests that the distribution of minerals (and, more specifically, their isoelectric points), as well as the aqueous phase pH at a given site, may have a significant impact on the DNAPL source zone architecture. PMID:20880604

Molnar, Ian L; O'Carroll, Denis M; Gerhard, Jason I

2011-01-25

45

Pulsating flow driven alteration in moving contact-line dynamics on surfaces with patterned wettability gradients  

NASA Astrophysics Data System (ADS)

The contact line dynamics over surfaces patterned with wettability gradients under pulsating flow condition are of essential importance in application areas ranging from the design of smart and effective microfluidic devices to the understanding of blood flow dynamics in narrow conduits. In the present study, we probe the capillary filling dynamics in a pulsatile flow environment, in an effort to explore the underlying flow physics. Presenting the results of frequency assisted contact line motion of two immiscible fluids over surfaces patterned with wettability gradients, we show how the interfacial dynamics are affected by the interplay of both the surface characteristics and flow pulsation. Our results reveal that the competition between two control parameters, the frequency and the amplitude of the imposed flow pulsation, may effectively be tuned to control the capillary filling dynamics significantly. The study, we present here, also suggests that by suitably tuning the control parameters, it is possible to control the capillary residence time over engineered locations which may, in turn, facilitate improved mixing and/or design of chemically active reaction stations.

Mondal, Pranab Kumar; DasGupta, Debabrata; Bandopadhyay, Aditya; Chakraborty, Suman

2014-08-01

46

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

NASA Astrophysics Data System (ADS)

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.

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

2012-08-01

47

Asymmetric Wettability Directs Leidenfrost Droplets  

SciTech Connect

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.

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

2014-01-01

48

Capillary breakup of Discontinuously Rate Thickening Suspensions  

E-print Network

In this study, we investigated the behavior of Discontinuously Rate Thickening Suspensions (DRTS) in capillary breakup, where a thin suspension filament breaks up under the action of surface tension forces. We performed ...

Zimoch, Pawel

2012-01-01

49

Nanofluid surface wettability through asymptotic contact angle.  

PubMed

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

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

2011-03-15

50

Autoclaving as a mean of modifying the soil wettability characteristics  

Microsoft Academic Search

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

Emilia Urbanek; Merche Bodi; Rick Shakesby; Stefan Doerr

2010-01-01

51

The Wettability of a Multi-Component DNAPL on Quartz and Iron Oxide Sands  

NASA Astrophysics Data System (ADS)

Dense nonaqueous phase liquids (DNAPLs) released to the subsurface often contain a variety of chemical constituents, via either co-disposal or intentional modification to increase their industrial efficacy. These additional constituents are often surface active compounds (surfactants)that partition to soil surfaces. The role that these surface active compounds that sorb to soil surfaces have on DNAPL migration is still poorly understood despite an increasing amount of work in the area. Most studies have focused on the role surface active chemicals play in altering the wettability of quartz sands. This research aims to extend the understanding of multi-component DNAPL transport to other porous media and under a variety of pH conditions. Specifically, the objective of this study was to compare the changes in the wettability of quartz and iron oxide sands in a tetrachloroethylene (PCE)/water system spiked with dodecylamine, a representative cationic surfactant. Wettability was assessed through: (i) contact angles measured on representative quartz and iron oxide-coated plates as well as (ii) contact angles measured directly on sands using an Axial Drop Symmetrical Analyzer apparatus; and (iii) capillary pressure-saturation relationships obtained via multi-step outflow experiments. In addition, two-dimensional sandbox experiments explored the influences of iron oxide and quartz sands on multicomponent DNAPL migration. Results suggest that quartz and iron oxide-coated sands exhibit different wetting characteristics under similar subsurface conditions.

Molnar, I.; O'Carroll, D.; Gerhard, J.

2009-05-01

52

Control of surface wettability via strain engineering  

NASA Astrophysics Data System (ADS)

Reversible control of surface wettability has wide applications in lab-on-chip systems, tunable optical lenses, and microfluidic tools. Using a graphene sheet as a sample material and molecular dynamic simulations, we demonstrate that strain engineering can serve as an effective way to control the surface wettability. The contact angles ? of water droplets on a graphene vary from 72.5° to 106° under biaxial strains ranging from -10% to 10% that are applied on the graphene layer. For an intrinsic hydrophilic surface (at zero strain), the variation of ? upon the applied strains is more sensitive, i.e., from 0° to 74.8°. Overall the cosines of the contact angles exhibit a linear relation with respect to the strains. In light of the inherent dependence of the contact angle on liquid-solid interfacial energy, we develop an analytic model to show the cos ? as a linear function of the adsorption energy E ads of a single water molecule over the substrate surface. This model agrees with our molecular dynamic results very well. Together with the linear dependence of E ads on biaxial strains, we can thus understand the effect of strains on the surface wettability. Thanks to the ease of reversibly applying mechanical strains in micro/nano-electromechanical systems, we believe that strain engineering can be a promising means to achieve the reversibly control of surface wettability.

Xiong, Wei; Liu, Jefferson Zhe; Zhang, Zhi-Liang; Zhen, Quan-Shui

2013-08-01

53

Droplet motion in one-component fluids on solid substrates with wettability gradients.  

PubMed

Droplet motion on solid substrates has been widely studied not only because of its importance in fundamental research but also because of its promising potentials in droplet-based devices developed for various applications in chemistry, biology, and industry. In this paper, we investigate the motion of an evaporating droplet in one-component fluids on a solid substrate with a wettability gradient. As is well known, there are two major difficulties in the continuum description of fluid flows and heat fluxes near the contact line of droplets on solid substrates, namely, the hydrodynamic (stress) singularity and thermal singularity. To model the droplet motion, we use the dynamic van der Waals theory [Phys. Rev. E 75, 036304 (2007)] for the hydrodynamic equations in the bulk region, supplemented with the boundary conditions at the fluid-solid interface. In this continuum hydrodynamic model, various physical processes involved in the droplet motion can be taken into account simultaneously, e.g., phase transitions (evaporation or condensation), capillary flows, fluid velocity slip, and substrate cooling or heating. Due to the use of the phase field method (diffuse interface method), the hydrodynamic and thermal singularities are resolved automatically. Furthermore, in the dynamic van der Waals theory, the evaporation or condensation rate at the liquid-gas interface is an outcome of the calculation rather than a prerequisite as in most of the other models proposed for evaporating droplets. Numerical results show that the droplet migrates in the direction of increasing wettability on the solid substrates. The migration velocity of the droplet is found to be proportional to the wettability gradients as predicted by Brochard [Langmuir 5, 432 (1989)]. The proportionality coefficient is found to be linearly dependent on the ratio of slip length to initial droplet radius. These results indicate that the steady migration of the droplets results from the balance between the (conservative) driving force due to the wettability gradient and the (dissipative) viscous drag force. In addition, we study the motion of droplets on cooled or heated solid substrates with wettability gradients. The fast temperature variations from the solid to the fluid can be accurately described in the present approach. It is observed that accompanying the droplet migration, the contact lines move through phase transition and boundary velocity slip with their relative contributions mostly determined by the slip length. The results presented in this paper may lead to a more complete understanding of the droplet motion driven by wettability gradients with a detailed picture of the fluid flows and phase transitions in the vicinity of the moving contact line. PMID:23004770

Xu, Xinpeng; Qian, Tiezheng

2012-05-01

54

Motion of Drops on Surfaces with Wettability Gradients  

NASA Technical Reports Server (NTRS)

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

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

2002-01-01

55

Motion of Drops on Surfaces with Wettability Gradients  

NASA Astrophysics Data System (ADS)

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

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

2002-11-01

56

Effect of the interfacial tension and wettability on the behaviour of unsaturated granular media  

NASA Astrophysics Data System (ADS)

The concept of "effective stress extended to unsaturated soils" is one of the most discussed concepts in soil mechanics today. This concept enters in the formulation of the constitutive laws of elastic as well as elastoplastic solid phases, and controls the stress-strain relations, the volume changes and the strength of the solid skeleton, independently of the amplitude of the pore water pressure. These last years, several researchers showed that the extended effective stress concept remains an effective tool to describe qualitatively and quantitatively the unified mechanical behavior of the soils, assuring continuity between saturated and unsaturated domains. This paper presents the effect of the air-water surface tension and wettability of the solid particles by the liquid in the formulation of the capillary force between the particles; this force, integrated in a representative elementary volume (REV), makes it possible to define a "capillary" stress ?'cap(pc), function of the capillary pressure pc. Taking into account the surface tension in the formulation of the capillary stress ?' cap is far from being negligible. Whereas this effect is negligible when the water content tends towards 0, it quickly becomes very important when the water content reaches a few percents. Validations were carried out on various loading paths and various materials.

Taibi, Said; Dumont, Matthieu; Fleureau, Jean-Marie

2009-06-01

57

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

SciTech Connect

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

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

2007-09-30

58

Versatile aluminum alloy surface with various wettability  

NASA Astrophysics Data System (ADS)

Various geometric microstructures on aluminum alloy surfaces were fabricated simply through SiC paper rubbing, and the wettability of the obtained surfaces was investigated thoroughly. The water contact angle increased firstly with the increasing particle size of the sandpaper, and then declined with further increase of the grits size, exhibiting a hydrophilic-hydrophobic-hydrophilic transition. The effect of surface geometric microstructure on the wetting behavior of aluminum alloy can be well rationalized in terms of the Cassie-Baxter model by considering the surface energy gradient. The present results not only enhance the in-depth understanding of the mechanism for the significant role of surface microstructure on the wettability of aluminum alloy, but also explore promising applications of versatile metallic surface in industries.

Lu, Baiping; Li, Ning

2015-01-01

59

Wettability of transition metal oxide surfaces  

Microsoft Academic Search

The wettability of transition metal oxide surfaces (TiO2, ZrO2 and HfO2) by water was investigated by measuring the contact angles using the sessile drop method. The oxide surfaces were prepared by thermal oxidation of polished metal foils of Ti, Zr and Hf, which had been polished to different levels of surface roughness. The surfaces were also characterized by optical microscopy,

Aiguo Feng; Benjamin J McCoy; Zuhair A Munir; Domenick Cagliostro

1998-01-01

60

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

SciTech Connect

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.

Chang, Y.C.; Mani, V.; Mohanty, K.K. [Univ. of Houston, TX (United States)

1997-08-01

61

Wettability patterning of hydroxyapatite nanobioceramics induced by surface potential modification  

NASA Astrophysics Data System (ADS)

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.

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

2006-04-01

62

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

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

63

The effects of fractional wettability on microbial enhanced oil recovery  

NASA Astrophysics Data System (ADS)

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.

Wildenschild, D.; Armstrong, R. T.

2011-12-01

64

Measurement of surface tension and viscosity by open capillary techniques  

DOEpatents

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

Rye,Robert R. (Albuquerque, NM), Yost,Frederick G. (Cedar Crest, NM)

1998-01-01

65

Wettability Induced Crack Dynamics and Morphology  

E-print Network

Substrate wettability alteration induced control over crack formation process in thin colloidal films has been addressed in the present study. Colloidal nanosuspension (53nm, mean particle diameter) droplets have been subjected to natural drying to outline the effects of substrate surface energies over the dry-out characteristics with emphasis on crack dynamics, crack morphology and underlying particle arrangements. Experimental findings indicate that number of cracks formed decreases with increase in substrate hydrophobicity. These physical phenomena have been explained based on the magnitude of stress dissipation incurred by the substrate. DLVO predictions are also found to be in tune with the reported experimental investigations.

Udita Uday Ghosh; Monojit Chakraborty; Aditya Bikram Bhandari; Suman Chakraborty; Sunando DasGupta

2014-12-03

66

IMPACT OF CAPILLARY AND BOND NUMBERS ON RELATIVE PERMEABILITY  

SciTech Connect

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.

Kishore K. Mohanty

2002-09-30

67

Pool boiling of nanoparticle-modified surface with interlaced wettability  

PubMed Central

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

2012-01-01

68

Multiple capillary biochemical analyzer  

DOEpatents

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.

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

1995-01-01

69

Water Tank with Capillary Air/Liquid Separation  

NASA Technical Reports Server (NTRS)

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.

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

2010-01-01

70

Capillary rheometry for thermosets  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

71

Surface wettability studies of PDMS using flame plasma treatment  

E-print Network

The flame plasma treatment studied in this thesis was able to oxidize the surface of Polydimethylsiloxane (PDMS) in a fraction of a second. It was found to be a much faster way to modify PDMS surface wettability than the ...

Wang, Xin C

2009-01-01

72

Effect of rust on the wettability of steel by water  

SciTech Connect

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}.

Lu, W.; Chung, D.D.L. [State Univ. of New York, Buffalo, NY (United States). Composite Materials Research Lab.] [State Univ. of New York, Buffalo, NY (United States). Composite Materials Research Lab.

1998-04-01

73

Leaf wettability decreases along an extreme altitudinal gradient  

Microsoft Academic Search

The duration and amount of water captured on leaves and its functional significance is highly varied. Leaf surface wettability\\u000a influences water absorption, gas exchange, pathogen infection, nutrient leaching, contamination by pollutants, self-cleaning\\u000a properties and in freezing environments the probability of extrinsic ice nucleation. To test the impact of environment on\\u000a the development of leaf wettability, this functional trait was measured

Biva Aryal; Gilbert Neuner

2010-01-01

74

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

NASA Astrophysics Data System (ADS)

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.

Al-Menhali, Ali; Krevor, Samuel

2014-05-01

75

Displaced capillary dies  

DOEpatents

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.

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

1982-01-01

76

Displaced capillary dies  

DOEpatents

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.

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

1984-01-01

77

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

NASA Astrophysics Data System (ADS)

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 (20?L) 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 ?m). 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.

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

2011-12-01

78

Switch isotropic/anisotropic wettability via dual-scale rods  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

79

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)

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.

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

2013-08-01

80

Forest Service -U.S. Department of Agriculture Soil Wettability and Wetting Agents...  

E-print Network

: soil formation; fire effects; soil erosion control; soil wettability; wetting agents; saturation.2 5 :116.6 Retrieval Terms: soil formation; fire effects; soil erosion control; soil wettability ------------------------------------------------------------- 10 Controlling Soil Erosion --------------------------------------------------------- 11 Applying

Standiford, Richard B.

81

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

PubMed

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

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

2014-08-01

82

Water-collecting behavior of nanostructured surfaces with special wettability  

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

83

Instant capillary origami  

NASA Astrophysics Data System (ADS)

A liquid drop impacting a thin elastic membrane forms a "dynamical capillary origami" on the very rapid capillary timescale. Dynamics is here a key ingredient that allows for shape selection of the elastocapillary bundle based only on the impact velocity. We study this phenomenon using a simplified 2D setup, where a drop impacts a narrow polymer strip. This experiment exhibits a surprisingly rich variety of phenomena: coupled capillary and elastic waves, drop breakup, jet ejection...We propose a very simple rod dynamics numerical model that mimics the complex fluid-structure interactions at play. The results of this model are in close agreement with the full experiment, both in the qualitative dynamics of folding and in the quantitative representation of the phase diagram of encapsulation. Eventually, we discuss how drop dynamics may induce anomalous encapsulation events where unexpectedly long strips are wrapped around drops.

Rivetti, Marco; Audoly, Basile; Neukirch, Sebastien; Josserand, Christophe; Antkowiak, Arnaud

2010-11-01

84

Capillary condenser/evaporator  

NASA Technical Reports Server (NTRS)

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.

Valenzuela, Javier A. (Inventor)

2010-01-01

85

Wettability of Nafion and Nafion/Vulcan carbon composite films.  

PubMed

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

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

2012-04-24

86

Wettability of Freon hydrates in crude oil\\/brine emulsions  

Microsoft Academic Search

The surface energy of petroleum hydrates is believed to be a key parameter with regard to hydrate morphology and plugging tendency in petroleum production. As of today, the surface energy of natural gas hydrates is unknown, but will depend on the fluids in which they grow. In this work, the wettability of Freon hydrates is evaluated from their behavior in

S. Høiland; K. M. Askvik; P. Fotland; E. Alagic; T. Barth; F. Fadnes

2005-01-01

87

Capillary electrophoresis - electrospray ionization mass spectrometry in small diameter capillaries  

SciTech Connect

Methods (such as small inner diameter capillaries) are being explored to increase analyte sensitivity in capillary electrophoresis- electrospray ionization/mass spectroscopy(CE-ESI/MS). Results are reported for melittin in a protein mixture, with 10 to 100 {mu}m ID capillaries; and for a mixture of aprotinin, cytochrome c, myoglobin, and carbonic anhydrase, with 5 to 50 {mu}m ID capillaries. It is shown that an increase in solute sensitivity occurs when small ID capillaries ({lt} 20 {mu}m) are used in CE-ESI/MS for both a peptide and a protein mixture. 3 figs. (DLC)

Wahl, J.H.; Goodlett, D.R.; Udseth, H.R.; Smith, R.D.

1992-06-01

88

Capillary origami Charlotte Pya  

E-print Network

spontaneously wrap the droplet? Yes, if driving capillary forces overcome the elastic bending resistance microsystems. However, capillarity may also drive the association of such microstructures into well- defined: spontaneous wrapping of a droplet with an elastic sheet," Phys. Rev. Lett. 98, 156103 2007 . a Present address

Bico,José

89

Microbial enhanced oil recovery and wettability research program  

SciTech Connect

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.

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

1991-07-01

90

Plant pathology Effects of adjuvants on herbicidal action.  

E-print Network

Plant pathology Effects of adjuvants on herbicidal action. III. Effects of petroleum and rapeseed after 24 h was 20% of the applied herbicide on the adaxial surface (poorly wettable), but only 4 Résumé — Effet d'adjuvants sur l'action herbicide. III. Effets d'huiles minérale et végétale sur l

Paris-Sud XI, Université de

91

Noise suppressing capillary separation system  

DOEpatents

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.

Yeung, Edward S. (Ames, IA); Xue, Yongjun (Norwich, NY)

1996-07-30

92

Trap state spectroscopy studies and wettability modification of hydroxyapatite nanobioceramics  

NASA Astrophysics Data System (ADS)

Sintered hydroxyapatite coatings on titanium-based implants demonstrate beneficial biocompatibility and osteoconductivity. It has been shown that charged surface states and bulk traps located in the vicinity of the surface of the hydroxyapatite coatings strongly influence wettability properties of the hydroxyapatite and may modify biocompatibility of these nanostructured bioceramics. Combination of high-resolution electron state spectroscopy methods, thermostimulated exoelectron emission, and thermoluminescence methods, applied in this work, have allowed studying electron trap energy spectrum of the hydroxyapatite bioceramics.

Aronov, Daniel; Rosenman, Gil

2007-02-01

93

Poor Soil Wettability: Does moisture alter measurement results?  

NASA Astrophysics Data System (ADS)

Poor soil wettability is a global problem, creating challenges to agriculture by plant drought stress and to soil stability in natural environments. Events that lead to poor soil wettability are varied, including natural and manmade events such as forest fires, hot dry environments, poor soil management or the application of post-consumer materials. Even though options offered in the literature for amelioration of the symptoms of hydrophobicity greatly differ, the basic techniques used to identify hydrophobic soil have changed very little over the past half-century. Recently, however, scientists have begun to question what these traditional techniques are actually measuring. One of the areas of interest is the relationship of hydrophobicity to moisture content, also termed reversible or seasonal hydrophobicity. Many studies suggest that changes in the organic matter structure as it is exposed to soil moisture leads to a reduction of the surface energy of particle surfaces. This study further complements that work by investigating how testing methods and soil-sample treatment impact water sorption of hydrophobic media, so as to make it appear that the surface energy has changed. The understanding of this phenomenon can lead to improved techniques for testing of hydrophobicity soil and also for soil management in agricultural areas by understanding the impact of soil moisture regimes on wettability.

Dragila, M. I.; Woolverton, P.; Horneck, D.; Kleber, M.

2013-12-01

94

Wettability changes of TiO2 nanotube surfaces  

NASA Astrophysics Data System (ADS)

This study examines the effect of environmental and experimental conditions, such as temperature and time, on the wettability properties of titania nanotube (TNT) surfaces fabricated by anodization. The fabricated TNTs are 60-130 nm inner diameter and 7-10 µm height. One-microliter water droplets were used to define the wettability of the TNT surfaces by measuring the contact angles. A digital image analysis algorithm was developed to obtain contact angles, contact radii and center heights of the droplets on the TNT surfaces. Bare titanium foil is inherently less hydrophilic with approximately 60°-80° contact angle. The as-anodized TNT surfaces are more hydrophilic and annealing further increases this hydrophilic property. Furthermore, it was found that the TNT surface became more hydrophobic when aged in air over a period of three months. It is believed that the surface wettability can be changed due to alkane contamination and organic contaminants in an ambient atmosphere. This work can provide guidelines to better specify the environmental conditions that changes surface properties of TNT surfaces and therefore affect their desirable function in specific applications such as orthopedic implants.

Shin, Dong Hwan; Shokuhfar, Tolou; Choi, Chang Kyoung; Lee, Seong-Hyuk; Friedrich, Craig

2011-08-01

95

Ultrasound assisted cleaning of ceramic capillary filter.  

PubMed

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

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

2010-08-01

96

The Effect of Contamination on Adhesive Strength: Wettability Characterization by the CSC Method  

Microsoft Academic Search

The correlation between the adhesive strength of joints of aluminum alloys and the wettability of their surfaces was studied. Two alloys, Al-1100 and Al-2024, were used, with two commercial epoxy adhesives, FM-73 and FM-300K, and the BR-127 primer. The wettability of the surfaces was modified by applying coatings of silicone oil and stearic acid at various concentrations. Wettability was characterized

Abraham Marmur; Hanna Dodiuk; Dora Pesach

1987-01-01

97

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

SciTech Connect

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.

Mukul M. Sharma; George J. Hirasaki

2003-09-01

98

Fingering Instabilities during Capillary Imbibition into Paper  

NASA Astrophysics Data System (ADS)

When a porous medium, such as a piece of paper, is placed into contact with a liquid reservoir, capillary action drives the liquid through the porous medium. The penetration distance L(t) of the liquid/air interface is typically described by the Lucas-Washburn equation, with any deviations normally occurring on a length scale set by the average pore size. Here we report that solutions with a sufficient amount of hydrophobic solute undergo a fingering instability during capillary imbibition into paper. The finger amplitudes are two to three orders of magnitude larger than the average pore size, suggesting that the typical capillary fingering mechanism is not operative. Instead, we demonstrate that the finger growth rate is directly proportional to the solute concentration, and is strongly mediated by the ambient relative humidity. We interpret the fingering in terms of an instability driven by solutal effects on the local imbibition velocity, and we discuss the implications for various applications including thin layer chromatography and paper-based microfluidics.

Young, N.; Higgins, B. G.; Ristenpart, W. D.

2010-11-01

99

Investigations on surface wettability of ZnO nanowires using UV LEDs for biosensing applications  

NASA Astrophysics Data System (ADS)

ZnO is a biocompatible material suitable for biosensors and microfluidic devices. Nanowires of ZnO tend to show hydrophobic nature which decelerates the adhesion/adsorption of biomolecules on the surface. This paper discusses the investigations on tuning the wettability of ZnO nanowires using UV LEDs. The spectral effect of LED emission on ZnO nanowires wettability has been studied. Results indicate that UV LEDs offer an advanced control on tuning the wettability of ZnO nanowires. The spectral investigations have provided significant insight into the role of irradiating wavelength of light on the wettability.

Bhavsar, K.; Prabhu, R.; Pollard, P.

2014-08-01

100

Alveolar Capillary Dysplasia  

PubMed Central

Alveolar capillary dysplasia with misalignment of the pulmonary veins (ACD/MPV) is a rare, fatal developmental lung disorder of neonates and infants. This review aims to address recent findings in the etiology and genetics of ACD/MPV and to raise awareness of this poorly known disease, which may also present as milder, unclassified forms. Successively discussed are what is known about the epidemiology, pathogenesis, pathophysiology, diagnostic indicators and approaches, genetic testing, treatment, and cases of delayed onset. The review concludes with suggestions for future directions to answer the many unknowns about this disorder. PMID:21471096

Stankiewicz, Pawel; Steinhorn, Robin H.

2011-01-01

101

Capillary suspensions: Particle networks formed through the capillary force  

E-print Network

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.

Erin Koos

2014-10-21

102

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

SciTech Connect

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.

Heath, Jason E.; Nemer, Martin B.; McPherson, Brian J. O. L. (University of Utah, Salt Lake City, UT); Dewers, Thomas A.; Kotula, Paul Gabriel

2010-12-01

103

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

SciTech Connect

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.

Petrusak, Robin (Advanced Resources International, Inc., Arlington, VA); Heath, Jason E.; McPherson, Brian J. O. L. (University of Utah, Salt Lake City, UT); Dewers, Thomas A.; Kotula, Paul Gabriel

2010-08-01

104

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

PubMed

Injection of carbon dioxide in deep saline aquifers is considered as a method of carbon sequestration. The efficiency of this process is dependent on the fluid-fluid and rock-fluid interactions inside the porous media. For instance, the final storage capacity and total amount of capillary-trapped CO2 inside an aquifer are affected by the interfacial tension between the fluids and the contact angle between the fluids and the rock mineral surface. A thorough study of these parameters and their variations with temperature and pressure will provide a better understanding of the carbon sequestration process and thus improve predictions of the sequestration efficiency. In this study, the controversial concept of wettability alteration of quartz surfaces in the presence of supercritical carbon dioxide (sc-CO2) was investigated. A novel apparatus for measuring interfacial tension and contact angle at high temperatures and pressures based on Axisymmetric Drop Shape Analysis with no-Apex (ADSA-NA) method was developed and validated with a simple system. Densities, interfacial tensions, and dynamic contact angles of CO2/water/quartz systems were determined for a wide range of pressures and temperatures relevant to geological sequestration of CO2 in the subcritical and supercritical states. Image analysis was performed with ADSA-NA method that allows the determination of both interfacial tensions and contact angles with high accuracy. The results show that supercritical CO2 alters the wettability of quartz surface toward less water-wet conditions compared to subcritical CO2. Also we observed an increase in the water advancing contact angles with increasing temperature indicating less water-wet quartz surfaces at higher temperatures. PMID:23627310

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

2013-06-11

105

Tapered capillary optics  

DOEpatents

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.

Hirsch, Gregory (365 Talbot Ave., Pacifica, CA 94044)

1998-01-01

106

Noise suppressing capillary separation system  

DOEpatents

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.

Yeung, E.S.; Xue, Y.

1996-07-30

107

Capillary optics for radiation focusing  

SciTech Connect

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.

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

108

Tailoring the wettability of nanocrystalline TiO 2 films  

NASA Astrophysics Data System (ADS)

The water contact angle (WCA) of nanocrystalline TiO 2 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.

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

2012-01-01

109

The wettability of selected organic soils in Poland  

NASA Astrophysics Data System (ADS)

The wettability was measured in the laboratory by means of two methods: Water Drop Penetration Time (WDPT) test and Thin Column Wicking (TCW) method. WDPT is fast and simple method and was used to investigate potential water repellency of analyzed samples. TCW is an indirect method and was used to determine contact angles and surface free energy components. The measurement was performed in horizontal teflon chambers for thin-layer chromatography, adapted for tubes 10 cm long. The experiment was carried out on muck soils (samples were taken from two levels of soil profile: 0-20 cm and 20-40 cm) and peat soils. There were two types of peats: low-moor peats and high moor peats. Samples of low-moor peats were taken from level 25-75 cm (alder peat) and 75-125cm (sedge peat) and 25-75 cm (peloid peat). Samples of high moor peats from level 25-175 cm (sphagnum peat) and 175-225 cm (sphagnum peat with Eriophorum). There was found no variability in persistence of potential water repellency but there were differences in values of contact angles of individual soil samples. Both muck and peat samples are extremely water repellent soils. Water droplets persisted on the surface of soils for more than 24 hours. Contact angles and surface free energy components for all samples were differentiated. Ranges of water contact angles for organic soils are from 27,54o to 96,50o. The highest values of contact angles were for sphagnum peats, and the lowest for muck soil from 20-40 cm level. It means, that there are differences in wettability between these samples. Muck soil is the best wettable and sphagnum peats is the worst wettable soil. If the content of organic compounds in the soil exceeds 40% (like in peats), the tested material displays only dispersion-type interactions. Therefore for peat soils, the technique of thin column wicking could only be used to determine the dispersive component γiLW. For muck soils it was also determined electron-acceptor (Lewis acid) γ+ and electron-donor (Lewis base) γ- surface free energy components. The authors gratefully acknowledge the Ministry of Science and Higher Education for financial support of this work (grant No. N N310 149335).

Ca?ka, A.; Hajnos, M.

2009-04-01

110

The impact of additives found in industrial formulations of TCE on the wettability of sandstone  

E-print Network

The impact of additives found in industrial formulations of TCE on the wettability of sandstone) that are often encountered in industrial solvent formulations. Wettability assessments were made on sandstone wetting preference of sandstone which frequently resulted in neutral wetting conditions. The large volume

Sheffield, University of

111

A COMPARATIVE STUDY OF THE WETTABILITY OF STEEL, CARBON, AND POLYETHYLENE FIBERS BY WATER  

E-print Network

A COMPARATIVE STUDY OF THE WETTABILITY OF STEEL, CARBON, AND POLYETHYLENE FIBERS BY WATER W. Lu, X at Buffalo, Buffalo, NY 14260-4400, USA (Received March 9, 1998; in final form April 10, 1998) ABSTRACT The wettability of fibers by water was found to increase in this order: polyethylene fiber, steel fiber

Chung, Deborah D.L.

112

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

NASA Astrophysics Data System (ADS)

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.

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

2011-07-01

113

Benign sinonasal capillary haemangioma.  

PubMed

Haemangiomas are benign fibrovascular tumours relatively that are common in the head and neck, where 60% of them occur Among the various categories of haemangiomas, lobular capillary haemangiomas (LCH) occur frequently on the skin, lips, buccal mucosa, tongue and gingiva. However, they are vanishingly rare in the paranasal sinuses. The imaging features of LCH are non-specific. The histological characteristics of LCH can also make diagnosis difficult as sometimes resemble highly vascular malignant tumours. This leads to the false preoperative diagnosis of suspected malignancy in many cases, which places the patient under unnecessary distress and anxiety. We present a case of LCH appearing as a suspicious nasal lesion of the lateral nasal wall with unilateral nasal obstruction, necrotic centre and epistaxis. The tumour was excised endoscopically in one operation including endoscopic medial maxillectomy. Further education about this lesion is deemed important as preoperative embolisation may be needed for a safe operation. PMID:25287393

Stubbs, Darren; Poulios, Aristotelis; Khalil, Hisham

2014-01-01

114

Applications of capillary optical fibers  

NASA Astrophysics Data System (ADS)

The paper updates and summarizes contemporary applications of capillary optical fibers. Some of these applications are straight consequence of the classical capillary properties and capillary devices like: rheometry, electrophoresis, column chromatography (gas and liquid). Some new applications are tightly connected with co-propagation (or counter-propagation) of micro-mass together with optical wave - evanescent or of considerable intensity. In the first case, the optical wave is propagated in a narrow (more and more frequently single-mode) optical ring core adjacent to the capillary hole. The optical propagation is purely refractive. In the second case, the intensity maximum of optical wave is on the capillary long axis, i.e. in the center of the hole. The optical propagation is purely photonic, i.e. in a Bragg waveguide (one dimensional photonic band-gap). The capillary hole is filled with vacuum or with propagated matter (gas, liquid, single atoms, continuous particle arrangement). Optical capillaries, filamentary and embedded, are turning to a fundamental component of nano- and micro-MOEMS.

Romaniuk, Ryszard

2006-10-01

115

Integrated multiplexed capillary electrophoresis system  

DOEpatents

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.

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

2002-05-14

116

Fog collecting biomimetic surfaces: Influence of microstructure and wettability.  

PubMed

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

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

2015-01-01

117

Improved Surface wettability of polyurethane films by Ultraviolet Ozone treatment  

SciTech Connect

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.

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

2010-07-01

118

Morphology modulating the wettability of a diamond film.  

PubMed

Control of the wetting property of diamond surface has been a challenge because of its maximal hardness and good chemical inertness. In this work, the micro/nanoarray structures etched into diamond film surfaces by a maskless plasma method are shown to fix a surface's wettability characteristics, and this means that the change in morphology is able to modulate the wettability of a diamond film from weakly hydrophilic to either superhydrophilic or superhydrophobic. It can be seen that the etched diamond surface with a mushroom-shaped array is superhydrophobic following the Cassie mode, whereas the etched surface with nanocone arrays is superhydrophilic in accordance with the hemiwicking mechnism. In addition, the difference in cone densities of superhydrophilic nanocone surfaces has a significant effect on water spreading, which is mainly derived from different driving forces. This low-cost and convenient means of altering the wetting properties of diamond surfaces can be further applied to underlying wetting phenomena and expand the applications of diamond in various fields. PMID:25280079

Tian, Shibing; Sun, Weijie; Hu, Zhaosheng; Quan, Baogang; Xia, Xiaoxiang; Li, Yunlong; Han, Dong; Li, Junjie; Gu, Changzhi

2014-10-28

119

Capillary electrophoresis electrospray ionization mass spectrometry interface  

DOEpatents

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.

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

1999-01-01

120

Impact of wettability alteration on two-phase flow characteristics of sandstones: A quasi-static description  

NASA Astrophysics Data System (ADS)

We describe a two-phase pore network simulator of drainage and imbibition which integrates a realistic representation of pore connectivity and morphology, a quasi-static description of fluid displacement mechanisms, and a sound representation of the wetting properties of a sedimentary rock and of their alteration. The simulator works with 3-D disordered networks of cylindrical ducts with triangular, square, and circular cross sections obtained directly from the analysis of microfocused computed tomography (CT) images of rock samples. All pore-level displacement mechanisms (piston type, snap off, and cooperative pore body filling) are considered with arbitrary receding and advancing contact angles. Bond invasion percolation description is used in primary drainage, while bond site invasion percolation with ordinary percolation on a dual network and compact cluster growth is used in secondary imbibition. In this paper, we resolve how to calculate the relative permeability of nonaqueous phase liquid (NAPL) in the quasi-static approximation of imbibition and illustrate spatial distribution of the clusters of trapped NAPL using our generalization to disordered networks of the Hoshen-Kopelman cluster-labeling algorithm. To understand the impact of wettability alteration on the capillary pressure and relative permeability functions, we perform a series of drainage and imbibition simulations by changing the range of advancing contact angles. Our study indicates that in imbibition, transport properties of a permeable solid are quite sensitive to the hysteresis between the receding and advancing contact angle. This sensitivity reflects competition among the different displacement mechanisms, which shapes the relative permeabilities, capillary pressures, and the distribution of the trapped NAPL.

Al-Futaisi, Ahmed; Patzek, Tad W.

2003-02-01

121

Electromagnetic Activation of Capillary Switches  

Microsoft Academic Search

By designing coupled droplet pairs with the appropriate length scale to promote surface tension as the dominant force, one can create bi-stable capillary switches. This bi-stability can be triggered by pressure pulses, surface chemistry, electroosmosis, or body forces. To exploit the latter, we designed a capillary switch with electromagnetic activation. The resulting setup consists of a sub-millimeter tube, overfilled with

Bernie Malouin; Rohan Dayal; Leila Parsa; Amir Hirsa

2008-01-01

122

Filling of charged cylindrical capillaries  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

123

Inverse Problem of Capillary Filling  

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

124

Tailoring surface hydrophilicity of porous electrospun nanofibers to enhance capillary and push-pull effects for moisture wicking.  

PubMed

In this article, liquid moisture transport behaviors of dual-layer electrospun nanofibrous mats are reported for the first time. The dual-layer mats consist of a thick layer of hydrophilic polyacrylonitrile (PAN) nanofibers with a thin layer of hydrophobic polystyrene (PS) nanofibers with and without interpenetrating nanopores, respectively. The mats are coated with polydopamine (PDOPA) to different extents to tailor the water wettability of the PS layer. It is found that with a large quantity of nanochannels, the porous PS nanofibers exhibit a stronger capillary effect than the solid PS nanofibers. The capillary motion in the porous PS nanofibers can be further enhanced by slight surface modification with PDOPA while retaining the large hydrophobicity difference between the two layers, inducing a strong push-pull effect to transport water from the PS to the PAN layer. PMID:25020135

Dong, Yuliang; Kong, Junhua; Phua, Si Lei; Zhao, Chenyang; Thomas, Noreen L; Lu, Xuehong

2014-08-27

125

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

126

Evaluation of Reservoir Wettability and its Effect on Oil Recovery.  

SciTech Connect

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.

Buckley, J.S.

1998-01-15

127

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

NASA Astrophysics Data System (ADS)

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.

Desai, Nikhil; Ghosh, Uddipta; Chakraborty, Suman

2014-06-01

128

Surface charges of oxides and wettability: Application to TiO2-SiO2 composite films  

NASA Astrophysics Data System (ADS)

The super-hydrophilicity which can exist at the interface between oxides and aqueous solutions is able to sustain industrial and domestic applications. Several experimental results obtained on TiO2-SiO2 composite thin films via a sol-gel route have confirmed a natural and persistent super hydrophilicity under standard atmosphere. This property can be easily photo-regenerated after a long aging period in ambient atmosphere using a short UV illumination. The electrochemical double layer which classically exists between oxide surfaces and aqueous solution is unfavorable to high wettability properties of ideal flat surfaces. The present study indicates how the surface rugosity and the disjoining pressure caused by surface charges are able to explain the stability of a prewetting film. This film can withstand to vaporization in a weakly under saturated atmosphere, having a protective action despite a carbon contamination brought by standard atmosphere.

Joud, J.-C.; Houmard, M.; Berthomé, G.

2013-12-01

129

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

NASA Astrophysics Data System (ADS)

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 ?m 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.

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

2013-07-01

130

Methods and preliminary measurement results of liquid Li wettability  

SciTech Connect

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 “?/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.

Zuo, G. Z., E-mail: zuoguizh@ipp.ac.cn; Hu, J. S.; Ren, J.; Sun, Z.; Yang, Q. X.; Li, J. G. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)] [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); Zakharov, L. E.; Mansfield, D. K. [Princeton Plasma Physics Laboratory, MS-27 P.O. Box 451, Princeton, New Jersey 08543 (United States)] [Princeton Plasma Physics Laboratory, MS-27 P.O. Box 451, Princeton, New Jersey 08543 (United States)

2014-02-15

131

Atmospheric plasma torch treatment of aluminium: Improving wettability with silanes  

NASA Astrophysics Data System (ADS)

This study investigates the effect of atmospheric pressure plasma torch (APPT) treatments on the surface of aluminium alloys. The influence of torch-to-sample distance, speed of treatment and ageing time is analyzed in terms of contact angles and surface energy. Results show that APPT treatment strongly increases the surface energy and wettability of aluminium surfaces. This is related to the formation of polar groups, as Fourier transform infrared (FTIR) spectroscopy has confirmed. In all conditions, hydrophobic recovery of aluminium surfaces takes place. Finally, the compatibility of the APPT treated aluminium substrate with ?-methacryloxypropyltrimethoxysilane (MPS) has been evaluated through adhesion work and spread tension, showing that it is possible to achieve a spontaneous wetting process of silane on aluminium.

Díaz-Benito, B.; Velasco, F.

2013-12-01

132

Evaluation of Reservoir Wettability and its Effect on Oil Recovery  

SciTech Connect

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.

Buckley, Jill S.

1999-11-09

133

Design and fabrication of zwitter-wettable nanostructured films.  

PubMed

Manipulating surface properties using chemistry and roughness has led to the development of advanced multifunctional surfaces. Here, in a nanostructured polymer film consisting of a hydrophilic reservoir of chitosan/carboxymethyl cellulose capped with various hydrophobic layers, we demonstrate the role of a third design factor, water permeation rate. We use this additional design criterion to produce antifogging coatings that readily absorb water vapor while simultaneously exhibiting hydrophobic character to liquid water. These zwitter-wettable films, produced via aqueous layer-by-layer assembly, consist of a nanoscale thin hydrophobic capping layer (chitosan/Nafion) that enables water vapor to diffuse rapidly into the underlying hydrophilic reservoir rather than nucleating drops of liquid water on the surface. We characterize these novel films using a quartz crystal microbalance with dissipation monitoring (QCM-D) and via depth-profiling X-ray photoelectron spectroscopy (XPS) in addition to extensive testing for fogging/antifogging performance. PMID:25494724

Lee, Hyomin; Gilbert, Jonathan B; Angilè, Francesco E; Yang, Rong; Lee, Daeyeon; Rubner, Michael F; Cohen, Robert E

2015-01-14

134

Local wettability tuning with laser ablation redeposits on PDMS  

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

135

Capillary wave measurements on helically-supported capillary channels  

NASA Astrophysics Data System (ADS)

NASA is considering power generation by the Rankine cycle to save weight on long-duration manned missions to the moon or Mars. Phase separation technology is critical to this process in microgravity. Arrays of capillary channels might be useful for filtering liquid drops from a flowing vapor. The efficiency of droplet capture by a helically-supported capillary channel is being studied. A droplet impinging on the channel launches capillary waves that propagate down the channel helping to dissipate some of the drop's kinetic energy. High-speed video of the channel combined with image processing allows for measurement of the amplitude and speed of the wave packets. Increasing the pitch of the support structure decreases the wave speed. An understanding of the dynamic response of the channel to drop impact is a first step in predicting drop-capture efficiency.

Chandurwala, Fahim; Thiessen, David

2010-10-01

136

Treatment process for capillary hemangioma  

PubMed Central

Background Hemangiomas, usually, present at the first few months of life and are the most common benign tumor in children. There are various therapeutic methods for hemangioma. Capillary hemangioma is a type of hemangiomas. The steps of treatment of a child with capillary hemangioma in Taleghani Hospital of Gorgan, Iran, are reported. Case report In this report, it is described an 18-month-old child with capillary hemangioma on the right side of face. She was presented to the hematologic clinic of Taleghani Hospital of Gorgan. Three drugs, including prednisolon, propranolol and interferon alpha-2b (IFN-?-2b), were used for treating this patient. At the end of treatment, good results were obtained. After that, laser therapy was performed for fading the lesions. Conclusion Prescription of drug was our first choice for treating capillary hemangioma and it had a positive result without any complications. We used propranolol and IFN-?-2b for treating capillary hemangioma because of their better effect on this patient. PMID:25254092

Mirbehbahani, NB; Rashidbaghan, A

2014-01-01

137

Western Blotting using Capillary Electrophoresis  

PubMed Central

A microscale Western blotting system based on separating sodium-dodecyl sulfate protein complexes by capillary gel electrophoresis followed by deposition onto a blotting membrane for immunoassay is described. In the system, the separation capillary is grounded through a sheath capillary to a mobile X-Y translation stage which moves a blotting membrane past the capillary outlet for protein deposition. The blotting membrane is moistened with a methanol and buffer mixture to facilitate protein adsorption. Although discrete protein zones could be detected, bands were broadened by ~1.7-fold by transfer to membrane. A complete Western blot for lysozyme was completed in about one hour with 50 pg mass detection limit from low microgram per milliliter samples. These results demonstrate substantial reduction in time requirements and improvement in mass sensitivity compared to conventional Western blots. Western blotting using capillary electrophoresis shows promise to analyze low volume samples with reduced reagents and time, while retaining the information content of a typical Western blot. PMID:21265514

Anderson, Gwendolyn J.; Cipolla, Cynthia; Kennedy, Robert T.

2011-01-01

138

Wettability conundrum: Discrepancies of soft contact lens performance in vitro and in vivo  

NASA Astrophysics Data System (ADS)

The recognition and appreciation of soft contact lenses as simple, efficient and aesthetically gratifying vision-correction devices is ever growing, especially among younger population. Stable thin tear film uniformly spread over corrective lens surface is essential for acute vision, and also for comfortable and safe contact lens wear. The significant efforts have been invested by the contact lens industry to develop soft lens surface that is completely wet by tear aqueous in the ocular environment. Number of the publications dedicated to the wettability properties of the soft hydrogel lenses is on the steady rise. However, the clinical results show that no unambiguous correlation emerges when lens surface wettability in vitro is judged against tear film stability evaluated in vivo. This paper assesses and compares the modern techniques used for evaluation of soft contact lens surface wettability and reports some findings regarding relations between lens surface wettability in vitro and in vivo.

Svitova, T. F.; Lin, M. C.

2011-08-01

139

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

E-print Network

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??m for Rz (roughness), <5°, ?75°, ...

O'Hanley, Harry

140

Wettability of electroless Ni in the under bump metallurgy with lead free solder  

Microsoft Academic Search

This study investigates the wettability of several lead-free solders, including Sn, Sn?Ag, and Sn?Bi, on electroless Ni (EN)\\u000a with various phosphorus content. The role of phosphorus on solder wettability is studied. Microstructure evolution in the\\u000a lead-free solder\\/EN joint is investigated with the aid of electron probe microanalyzer (EPMA) to relate metallurgical reactions\\u000a between the solder and the EN. The SN

Bi-Lian Young; Jenq-Gong Duh; Bi-Shiou Chiou

2001-01-01

141

Nonsteady Flow in Capillary Tubes  

NASA Astrophysics Data System (ADS)

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.

Hara, Ayako

2000-03-01

142

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

143

Wettability measurement apparatus for porous material using the modified Washburn method  

NASA Astrophysics Data System (ADS)

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.

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

2013-12-01

144

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

PubMed

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

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

2014-07-01

145

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

PubMed

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

Henry, David

2007-09-15

146

Multiplexed fluorescence detector system for capillary electrophoresis  

DOEpatents

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.

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

1996-03-12

147

Multiplexed fluorescence detector system for capillary electrophoresis  

DOEpatents

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.

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

1994-06-28

148

Multiplexed fluorescence detector system for capillary electrophoresis  

DOEpatents

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.

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

1994-06-28

149

On numerical modeling of capillary barriers  

Microsoft Academic Search

A capillary barrier arises in unsaturated conditions at the contact of a fine layer of soil overlying a coarse layer of soil. If such a contact is tilted, infiltrating moisture in the fine layer will be diverted and flow down the contact as capillary diversion. Capillary barriers can occur naturally in layered heterogeneous systems, or they can be engineered for

Curtis M. Oldenburg; Karsten Pruess

1993-01-01

150

Recent advances in pressurized capillary electrochromatography  

Microsoft Academic Search

Pressurized capillary electrochromatography (pCEC) is an analytical technique that has attracted increased interests in recent years. In pCEC, both pressure and electric field are applied to a capillary column to achieve separation of analytes. It combines various aspects of capillary electrochromatography (CEC) and liquid chromatography (LC). In this review, recent developments, both theoretical and experimental, were presented. The practical aspects

Xue Gu; Xiaojing Huang; Chao Yan

151

Malpighi and the Discovery of Capillaries  

Microsoft Academic Search

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

J. M. S. Pearce

2007-01-01

152

Consistency of three-phase capillary entry pressures and pore phase occupancies  

NASA Astrophysics Data System (ADS)

Using the general equation for the true three-phase capillary entry pressures [van Dijke MIJ, Sorbie KS. Three-phase capillary entry conditions in pores of non-circular cross-section. J Colloid Interf Sci 2003;260:385-97, van Dijke MIJ, Lago M, Sorbie KS, Araujo M. Free energy balance for three fluid phases in a capillary of arbitrarily shaped cross-section: capillary entry pressures and layers of the intermediate-wetting phase. J Colloid Interf Sci 2004;277:184-201], we investigate for a single pore of uniform but arbitrary wettability the consistency of the relation between the pressure combinations and the pore phase occupancies in a three-phase system. The solutions of this equation corresponding to all possible displacements arising in three-phase flow are plotted in a single graph for two of the radii of curvature, which are equivalent to the phase pressure combinations. Consequently, this graph presents a delineation of the radius (pressure) space corresponding to different pore phase occupancies and we show that the underlying pressure-occupancy relation is unique using a free energy argument. The relation is presented for two very different parameter combinations. We explore how it can be extended when additional restrictions apply, for example those arising from lack of phase availability in an interconnected network. Using a capillary bundle of pores with triangular cross-section, we show the consequences for three-phase displacement processes if capillary entry pressures are and are not chosen consistently, the latter being common practice in all current three-phase pore network models. Displacements in both a water-wet and in a mixed-wet system are studied. The main conclusions from this work are that for a single pore different parameter combinations may lead to very different, but unique, pressure-occupancy relations. The saturation paths resulting from three-phase flow calculations in a capillary bundle of triangular pores are often significantly different using the true three-phase conditions as opposed to using inconsistent (two-phase) conditions, in particular in a mixed-wet system. Such large differences may also occur in interconnected pore network models, but only when continuity of the phases is high. The results indicate that, when the true conditions are used, there exists also a unique relation between the pressure combinations and the (bulk) occupancies in a bundle of pores with non-circular cross-section, similar to the relation for a bundle of cylindrical pores.

van Dijke, M. I. J.; Sorbie, K. S.

2007-02-01

153

Chemical modification of polymeric surfaces to promote wettability and reactivity  

NASA Astrophysics Data System (ADS)

For the past few years, low-k dielectric polymers have had a major impact on the advanced integrate circuit technologies. Their potential use as interlayer dielectric combined with a low resistivity metal as the conducting line (e.g. copper) in interconnects can reduce the resistivity-capacity delay. However, in order to successfully integrate copper and low-k dielectrics for further use, it is first necessary to understand the interfacial interaction between copper and low-k dielectric. This thesis work presents a systematic study with the primary goal of improving the polymer surface wettability and reactivity. Two hydrocarbon polymers, SiLK(TM) and Parylene, were used in this study, and the polymer surfaces were modified by either acid or plasma treatments. The change of surface morphology and surface chemistry due to the treatment was analyzed by atomic force microscopy (AFM) and x-ray photoelectron spectroscopy (XPS), respectively. A significant decrease of water droplet contact angle after the surface treatment reveals that the polymer surface wettability increases. It is found that the main factor in reducing the water droplet contact angle is the formation of oxygen and/or nitrogen functional groups on the polymer surface rather than an increase in the polymer surface roughness. The plasma treatment introduces a larger amount of functional groups onto the polymer surface than the acid treatment. The SiLK's crosslink structure is better withstanding the plasma force than the Parylene's linear polymer. Consequently, there are larger amounts of functional groups formed on the SILK surface than on the Parylenc surface. An additional study reveals that the formation of functional groups on the polymer surface also increases the polymer surface reactivity and allows Tetrasulfide self-assembled monolayer growth on the treated polymer surfaces. The existence of functional groups and Tetrasulfide moiety markedly improves the copper interfacial interaction. It was observed that copper undergoes a reaction with oxygen functional groups, nitrogen functional groups and Tetrasulfide moiety. Further study of metallorganic Cu(hfac)2 adsorption indicates that the existence of functional groups on the plasma-treated polymer surface significantly enhances the Cu(hfac)2 chemisorption onto the polymer surface. The Cu(hfac)2 self-limiting growth behavior remains after it is adsorbed onto the polymer surface.

Pimanpang, Samuk

154

Capillary forces between sediment particles and an air-water interface.  

PubMed

In the vadose zone, air-water interfaces play an important role in particle fate and transport, as particles can attach to the air-water interfaces by action of capillary forces. This attachment can either retard or enhance the movement of particles, depending on whether the air-water interfaces are stationary or mobile. Here we use three standard PTFE particles (sphere, circular cylinder, and tent) and seven natural mineral particles (basalt, granite, hematite, magnetite, mica, milky quartz, and clear quartz) to quantify the capillary forces between an air-water interface and the different particles. Capillary forces were determined experimentally using tensiometry, and theoretically assuming volume-equivalent spherical, ellipsoidal, and circular cylinder shapes. We experimentally distinguished between the maximum capillary force and the snap-off force when the air-water interface detaches from the particle. Theoretical and experimental values of capillary forces were of similar order of magnitude. The sphere gave the smallest theoretical capillary force, and the circular cylinder had the largest force due to pinning of the air-water interface. Pinning was less pronounced for natural particles when compared to the circular cylinder. Ellipsoids gave the best agreement with measured forces, suggesting that this shape can provide a reasonable estimation of capillary forces for many natural particles. PMID:22423648

Chatterjee, Nirmalya; Lapin, Sergey; Flury, Markus

2012-04-17

155

Capillary electrophoresis for drug analysis  

NASA Astrophysics Data System (ADS)

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.

Lurie, Ira S.

1999-02-01

156

Gradient elution in capillary electrochromatography  

SciTech Connect

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.

Anex, D.; Rakestraw, D.J. [Sandia National Labs., Livermore, CA (United States); Yan, Chao; Dadoo, R.; Zare, R.N. [Stanford Univ., CA (United States). Dept. of Chemistry

1997-08-01

157

Influence of variable substrate geometry on wettability and cellular responses.  

PubMed

In this report, we evaluate the impact of a systematic change to the extracellular environment on cell morphology and functionality by combining the inherent properties of biocompatible polymers such as polydimethylsiloxane and polycaprolactone with a specific surface response. By microstructuring pillars and pits on the substrates, varying spacing and height of the structures, we investigate the role of topography in fibroblast cell adhesion and viability. The change of wetting behaviour was tailored and evaluated in terms of contact angle measurements. It was shown that the range of micro-scale physical cues at the interface between the cells and the surrounding environment affects cell shape and migrations, indicating a tendency to respond differently to higher features of the micro-scale. We found that surface topography seems dominant over material wettability, fibroblasts responded to variations in topography by altering morphology and migrating along the direction of spacing among the features biased by the height of structures and not by the material. It is therefore possible to selectively influence either cell adhesion or morphology by choosing adequate topography of the surface. This work can impact in the design of biomaterials and can be applied to implanted biomedical devices, tissue engineering scaffolds and lab on chip devices. PMID:23270757

Cortese, Barbara; Riehle, Mathis O; D'Amone, Stefania; Gigli, Giuseppe

2013-03-15

158

Wettability model for various-sized droplets on solid surfaces  

NASA Astrophysics Data System (ADS)

The wetting phenomenon is crucial for the formation of stable liquid films on solid surfaces. The wettability of a liquid on a solid surface is characterized by the Young equation, which represents an equilibrium condition of a droplet at the three phase contact line. In general, the surface force in the vertical direction on a solid surface is ignored because of the resistance of the solid surface. However, considering the adhesion energy of the droplet rather than the force balance at the contact line, the vertical component of the surface force can be expected to be an important factor during wetting. Based on this concept, an analytical model is developed herein by considering the energy balance including adhesion forces acting not only in the horizontal but also in the vertical direction, in addition to the effect of gravity on the droplet. The validity of the developed model is then evaluated by experimental observation of the wetting phenomena of droplets on low- and high-surface-energy solids. Existing data are also used for evaluation of our model. The developed model describes the wetting phenomena of droplets with sizes ranging from nano- to millimeters under all experimental conditions and exhibits universality. In addition, on the basis of our model, the line tension is discussed. The results indicate that the line tension approach may be considered as a method to explain wetting phenomena by considering gravitational potential and other macroscopic parameters as a single parameter (i.e., line tension).

Yonemoto, Yukihiro; Kunugi, Tomoaki

2014-08-01

159

Surface wettability of titania thin films with increasing Nb content  

NASA Astrophysics Data System (ADS)

TiO2 and TiO2/Nb amorphous thin films were grown on glass substrates by a sol-gel technique (spin coating). Films' surface composition, structure, and morphology were derived from x-ray photoelectron spectroscopy, x-ray diffraction, and atomic force microscopy data. The investigated films showed a smooth surface (roughness values below 5 nm). A separate surface wettability investigation showed that by increasing the Nb amount in pristine titania films results in a decrease of contact angle (CA) values from 40° to nearly 0°, thus, indicating a super-hydrophilic conversion under UV illumination. This conversion rate is greatly enhanced by increasing the Nb content, the surface super-hydrophilic behavior occurring after a couple of minutes in the TiO2/Nb samples, but after 4 h in the pristine titania specimen. The current results are discussed in terms of the optical band gap shift towards higher energies, by increasing the Nb content in the films, a process explained based on small polaron hopping model.

Mardare, Diana; Yildiz, Abdullah; Girtan, Mihaela; Manole, Alina; Dobromir, Marius; Irimia, Mihaela; Adomnitei, Catalin; Cornei, Nicoleta; Luca, Dumitru

2012-10-01

160

Development of functional polymer surfaces with controlled wettability.  

PubMed

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

Anastasiadis, Spiros H

2013-07-30

161

Surface wettability plays a significant role in gecko adhesion underwater  

PubMed Central

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

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

2013-01-01

162

Pore-Lining Composition and Capillary Breakthrough Pressure of Mudstone Caprocks: Sealing Efficiency of Geologic CO2 Storage Sites  

NASA Astrophysics Data System (ADS)

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., < ~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. Sandia National Laboratories is a multi-program laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000.

Heath, J. E.; Dewers, T. A.; McPherson, B. J.; Kotula, P. G.

2010-12-01

163

Capillary filling dynamics of viscoelastic fluids  

NASA Astrophysics Data System (ADS)

We consider the filling of a capillary by a viscoelastic fluid described by the Phan-Thien-Tanner (PTT) constitutive behavior. By considering both vertical capillary filling and horizontal capillary filling, we demarcate the role played by gravity and fluid rheology towards long-time oscillations in the capillary penetration depth. We also consider the isothermal filling of the capillary for a closed channel and thus bring out the fundamental differences in the nature of capillary filling for PTT and Newtonian fluids for closed channels in comparison to open channels. Through a scaling analysis, we highlight a distinct viscoelastic regime in the horizontal capillary filling which is in contrast to the Washburn scaling seen in the case of Newtonian fluids. Such an analysis with a very general constitutive behavior is therefore expected to shed light on many areas of microfluidics which focus on biofluids that are often well described by the PTT constitutive behavior.

Bandopadhyay, Aditya; Ghosh, Uddipta; Chakraborty, Suman

2014-05-01

164

Geological applications of capillary pressure: A review  

SciTech Connect

Capillary pressure concepts can be used to evaluate reservoir rock quality, expected reservoir fluid saturations and depths of fluid contacts, thickness of transition zone, seal capacity, and pay versus nonpay, and to approximate recovery efficiency. Mercury-injection capillary pressure is typically favored for geological applications, such as inferring the size and sorting of pore throats. The differences between mercury injection and withdrawal curves can provide information on recovery efficiency. The height above free water level can be determined by comparing capillary pressure data to hydrocarbon shows and measured fluid saturations. Capillary pressure data can also be used to distinguish reservoir from nonreservoir rocks and pay from nonpay on the basis of nonwetting-phase saturations. Other applications of capillary pressure data include relating capillary pressure to absolute and relative permeabilities, and using porosimetry to investigate pore-level heterogeneity. This paper reviews geological applications and interpretation of capillary pressure in reservoir studies.

Vavra, C.L.; Kaldi, J.G. (ARCO Exploration and Production Technology, Plano, TX (United States)); Sneider, R.M. (Robert M. Sneider Exploration, Inc., Houston, TX (United States))

1992-06-01

165

Development of a Contingency Capillary Wastewater Management Device  

NASA Technical Reports Server (NTRS)

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.

Thomas, Evan A.

2010-01-01

166

Leukocyte margination in alveolar capillaries: interrelationship with functional capillary geometry and microhemodynamics.  

PubMed

The pulmonary capillary microvasculature harbors a large pool of intravascularly marginated leukocytes. In this study, we investigated the interrelationship of leukocyte margination with characteristics of functional capillary geometry and microhemodynamics in alveolar capillary networks. In 22 anesthetized rabbits we assessed functional capillary density, average capillary length, red blood cell velocity and leukocyte kinetics in alveolar capillary networks in vivo by intravital fluorescence microscopy. In alveolar wall areas of 12,800 +/- 1,800 microm(2), we detected 3.6 +/- 0.5 sticking leukocytes and 21.0 +/- 1.9 functional capillary segments with an average capillary length of 35.7 +/- 2.1 microm. We calculated that approximately 15% of functional capillary segments are blocked by marginated leukocytes. Leukocyte margination was predominantly observed in capillary networks characterized by a high functional capillary density, short capillary segments and low red blood cell velocities. The multitude of interconnected capillary channels in these networks may allow alveolar blood flow to bypass marginated leukocytes. Hence, this interrelationship may be relevant for maintenance of adequate alveolar perfusion and low capillary network resistance despite excessive leukocyte margination in the pulmonary microvasculature. Local microhemodynamic factors may play a regulatory role in the spatial distribution of leukocyte margination. PMID:10474041

Kuebler, W M; Kuhnle, G E; Goetz, A E

1999-01-01

167

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

PubMed

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)/?m(2) and 3.3×10(6)-2.8×10(7) nm(3)/?m(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

Varin, Kari J Moses; Cohen, Yoram

2014-12-15

168

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

PubMed

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). PMID:25173032

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

2014-08-28

169

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

PubMed

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

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

2009-01-01

170

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

NASA Astrophysics Data System (ADS)

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).

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

2014-08-01

171

Capillary electrophoresis systems and methods  

SciTech Connect

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.

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

172

Evaluation of Reservoir Wettability and its Effect on Oil Recovery.  

SciTech Connect

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. Crude Oil/Brine/Solid Interactions The interactions between crude oils, brines, and solid surfaces have been studied using a variety of core materials as well as in two-dimensional micromodels of interconnecting pores and throats. In the work reported this quarter, these same interactions have been applied to create mixed-wet conditions in a very simple model porous material, namely square glass tubes which have the advantage of permitting dual occupancy by both wetting and nonwetting phases simultaneously. The interactions between crude oil samples from Prudhoe Bay have been studied on a variety of surfaces. Figure 1 outlines the regions of stable and unstable brine compositions with A-93, a sample from Prudhoe Bay, and glass surfaces. A brine with pH 8 and 1 M concentration of NaCl produces a stable water film between glass and A-93 crude oil. If the brine has pH 4 and 0.01M NaCl, thin films of water are unstable and oil contacts the glass. Between these extremes is a wide band of brine compositions for which film stability is conditional.

Buckley, J.S.

1997-10-01

173

Treelike networks accelerating capillary flow  

NASA Astrophysics Data System (ADS)

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.

Shou, Dahua; Ye, Lin; Fan, Jintu

2014-05-01

174

Treelike networks accelerating capillary flow.  

PubMed

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

Shou, Dahua; Ye, Lin; Fan, Jintu

2014-05-01

175

A molecular dynamics study of the force between planar substrates due to capillary bridges.  

PubMed

Molecular dynamics simulations are used to study capillary liquid bridges between two planar substrates and the origin, strength and range of the resulting force between them. Pairwise interactions are described by the Lennard-Jones potential. Surface wettability is tuned by varying the fluid-substrate well depth interaction parameter. The force between the substrates due to a bridge of liquid is estimated by different methods including non-equilibrium simulations of moving substrates connected by liquid bridges and macroscopic balance of forces. The latter involves knowledge of liquid-vapor interfacial free energy, curvature radii, radius of wetted area and contact angle at the triple-phase contact line. All these physical quantities are estimated from equilibrium simulations. The force is attractive when the substrates are solvophilic or moderately solvophobic; and thus for cavities surrounded by the same liquid the force is attractive even when the substrates are moderately solvophilic. Two threshold values for the fluid-substrate potential interaction parameter can be identified; one for which the effective interaction between substrates due to liquid bridges changes from repulsive to attractive and another for which the capillary bridge becomes mechanically unstable and breaks into droplets. PMID:24863777

Saavedra, Jorge H; Rozas, Roberto E; Toledo, Pedro G

2014-07-15

176

The conversion of wettability in transparent conducting Al-doped ZnO thin film  

NASA Astrophysics Data System (ADS)

We report on the systematic changes of surface wettability in one of the most promising transparent conducting oxide materials, Al-doped ZnO (AZO) thin films. It was revealed that the characteristic surface wettability, which would make a key role in adhesion with other layers of optoelectronic device, can be largely changed by Al concentrations and film growth temperature. Keeping the electrical conductivity constant, the water contact angle (WCA) of a 2 mol% AZO film was changed by about 50 ?C depending on the surface roughness. In the samples grown at 300 ?C, the roughness enhancement was large and a hydrophobic surface formed, whereas in the samples grown at 500 ?C a hydrophilic surface formed. We attributed the variation in surface wettability with growth temperature to changes in surface morphology. This result suggests that 2 mol% Al doping concentration can be considered as a critical concentration in changing of surface morphology of AZO as well as in electrical properties.

Cho, Yong Chan; Cha, Su-Young; Shin, Jong Moon; Park, Jeong Hun; Park, Sang Eon; Cho, Chae Ryong; Park, Sungkyun; Pak, Hyuk K.; Jeong, Se-Young; Lim, Ae-Ran

2009-04-01

177

Janus si micropillar arrays with thermal-responsive anisotropic wettability for manipulation of microfluid motions.  

PubMed

In this paper, Janus micropillar array (MPA) with fore-aft controllable wettability difference was demonstrated. With two-step modification process, we successfully decorate the Janus pillar skeletons with wettability-switchable polymer brush on one side and hydrophilic self-assembled monolayer on the other. Owing to the switchable wettability of the polymer brush, the patterned surface could switch between anisotropic wetting and isotropic wetting at different temperatures, which gives the possibility of coupling the well-designed surface with microfluidic channel to manipulate the microfluid motion. Additionally, a further photothermal control of microfluid was also established based on the thermal-responsive Janus MPA through introducing infrared light to adjust the temperature of the microfluidic system. We believe that the thermal-responsive Janus micropillar arrays would provide a new strategy to control the flow and motion of fluids in microfluidic channels and show potential applications in the future microfluidic chips. PMID:25479323

Wang, Tieqiang; Chen, Hongxu; Liu, Kun; Wang, Shuli; Xue, Peihong; Yu, Ye; Ge, Peng; Zhang, Junhu; Yang, Bai

2015-01-14

178

PUBLISHED ONLINE: 10 NOVEMBER 2014 | DOI: 10.1038/NPHYS3145 Wettability-independent bouncing on flat surfaces  

E-print Network

LETTERS PUBLISHED ONLINE: 10 NOVEMBER 2014 | DOI: 10.1038/NPHYS3145 Wettability millimetres to a few centimetres to fall onto carefully cleaned and dust-free surfaces of variable wettability =90 (Supplementary Movie 2). This remarkable independence of liquid­substrate interaction strongly

Loss, Daniel

179

EFFECT OF RUST ON THE WETTABILITY OF STEEL BY WATER W. Lu and D.D.L. Chung1  

E-print Network

EFFECT OF RUST ON THE WETTABILITY OF STEEL BY WATER W. Lu and D.D.L. Chung1 Composite Materials Research Laboratory, State University of New York at Buffalo, Buffalo, NY 14260-4400, USA (Received-carbon steel in water, was found to improve the wettability of steel by water. The advancing contact angle

Chung, Deborah D.L.

180

Materials Science and Engineering A245 (1998) 293299 The wettability of silicon carbide by AuSi alloys  

E-print Network

Materials Science and Engineering A245 (1998) 293­299 The wettability of silicon carbide by Au. Keywords: Wettability; Contact angle; Liquid metals; Silicon carbide 1. Introduction The interface properties of silicon carbide­liquid metals (wetting, adhesion, contact interaction) are im- portant

Grigoriev, Alexei

181

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

SciTech Connect

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.

Hu, W.

1994-08-01

182

Mathematical modeling of heat transfer, condensation, and capillary flow in porous insulation on a cold pipe  

Microsoft Academic Search

Porous insulation used on pipes carrying cold fluids suffers thermal degradation due to condensation of water vapor and the build up of water in the insulation. Recently, it has been suggested that the thermal degradation can be significantly reduced by wrapping a hydrophilic wick fabric on the cold pipe. The capillary action of the fabric, aided by gravity, allows the

M. K. Choudhary; K. C. Karki; S. V. Patankar

2004-01-01

183

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

NASA Astrophysics Data System (ADS)

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 mm•h-1. The 10% BC decreased runoff by up to 40%. At higher rainfall intensities (45 and 55 mm•h-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

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

2012-04-01

184

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

SciTech Connect

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.

Jill S. Buckley; Norman R. Morrow

2006-01-01

185

Pharmacological effects of various venoms on cutaneous capillary leakage.  

PubMed

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

Burnett, J W; Calton, G J

1986-01-01

186

Capillary rise kinetics of some building materials.  

PubMed

The presence of water in masonry is one of the main factors in deterioration. Capillary rise is the most usual mechanism of water penetration into building materials. In this study the kinetics of the capillary rise phenomenon was studied for various building materials: four stones, two bricks, and six plasters. A first-order kinetic model was proposed, in which the equilibrium moisture height derived from Darcy law. The capillary height time constant found to be strongly affected by the material characteristics. Moreover, the capillary height time constant can be predicted if the average pore radius of the materials is known. PMID:15752811

Karoglou, M; Moropoulou, A; Giakoumaki, A; Krokida, M K

2005-04-01

187

Morphometric analysis of sparse capillary networks.  

PubMed

Two methods were used to assess the heterogeneity of capillary supply to muscles of widely differing metabolic capacity and fibre size. Using the method of capillary domains (DOM; Hoofd et al., 1985) and the closest-individual method (CI; Kayar et al., 1981) radii of Kroghian cylinders (R) can be calculated, and the heterogeneity of their lognormal distribution represented by the logarithmic standard deviation (Log SD). Both methods yield similar values for mean R in a tissue. DOM is more direct and quicker than CI, and may be particularly useful in the analysis of capillary oxygen supply during functional hypertrophy and in muscle regeneration where a broad distribution of fibre areas may be found. Despite a 500-fold range of capillary density, to a minimum of 20 capillaries mm-2, heterogeneity of capillary supply was similar in all muscles, indicating a functionally homologous spatial distribution. The relationship between number of fibres overlapped by a capillary domain, and domain area has zero correlation in most tissues but shows a negative trend in fish fast muscle, reflecting hyperplastic and hypertrophic growth. Capillary/fibre ratio is inappropriate for sparse networks whereas the cumulative fraction of domains vs fibre area shows a strong correlation, suggesting that maximal oxygen supply to muscle fibres is not restricted to contiguous capillaries, but also involves those remote from the fibre surface. PMID:3673711

Egginton, S; Turek, Z; Hoofd, L

1987-01-01

188

Factors in snake venoms that increase capillary permeability.  

PubMed

Capillary permeability increasing (CPI) activity is a phenomenon of the microvasculature caused by many agents such as snake venoms, histamine, 5-hydroxytryptamine (5-HT), prostaglandins and leukotrienes. Since no systematic study has been done to determine what components of snake venom cause CPI activity, a CPI factor from Naja naja atra (Taiwan cobra) venom was isolated using intravenous injections of Evan's blue dye as the indicator of increased permeability and the factor's properties were extensively studied. Cardiotoxin from Naja naja kaouthia (Thailand cobra) and Mojave toxin from Crotalus scutulatus scutulatus (Mojave rattlesnake) venoms demonstrated CPI activity. Postsynaptic neurotoxins from an elapid and a hydrophid and myotoxin a from Crotalus viridis viridis (prairie rattlesnake) showed no CPI activity at the dose studied. The purified CPI active component from Naja naja atra venom was found to have cardiotoxic activity. Therefore, Elapidae cardiotoxins are CPI active factors. However, CPI activity is not due to cardiotoxins alone as the presynaptic neurotoxin, Mojave toxin, also showed CPI activity. Selective inhibitors were used to indicate possible mechanisms of action on the capillaries by Naja naja atra venom and Crotalus scutulatus scutulatus venom. The histamine H1-receptor blockers diphenhydramine, promethazine, and cyproheptadine were effective against both venoms in preventing increased capillary permeability. These results suggested that histamine release activity is the most likely mechanism resulting in CPI activity from these venoms. PMID:2576052

Miller, R A; Tu, A T

1989-11-01

189

A variational approach to the study of capillary phenomena  

NASA Technical Reports Server (NTRS)

The problem of determining the free surface of a liquid in a capillary tube, and of a liquid drop, sitting first on a horizontal plane and then on more general surfaces is considered. With some modifications, the method applies to the study of pendent drops and of rotating drops as well. The standard capillary problem, i.e. the determination of the free surface of a liquid in a thin tube of general cross section, which resuls from the simultaneous action of surface tension, boundary adhesion and gravity is discussed. It turns out that in this case the existence of the solution surface depends heavily on the validity of a simple geometric condition about the mean curvature of the boundary curve of the cross section of the capillary tube. Some particular examples of physical interest are also be discussed. Liquid drops sitting on or hanging from a fixed horizontal plane are discussed. The symmetry of the solutions (which can actually be proved, as consequence of a general symmetrization argument) now plays the chief role in deriving both the existence and the regularity of energy-minimizing configurations. When symmetry fails (this is the case, for example, when the contact angle between the drop and the plate is not constant, or when the supporting surface is not itself symmetric), then more sophisticated methods must be used. Extensions in this direction are outlined.

Emmer, M.; Gonzalez, E.; Tamanini, I.

1982-01-01

190

Interface motion of capillary-driven flow in rectangular microchannel.  

PubMed

In microchannel flow, gas-liquid interface behavior is important for developing a wide range of microfluidic applications, especially in passive microfluidic systems. This paper presents a discussion of interface motion driven by capillary action in a microchannel. We have extended the theory beyond the previous theory of capillary rise problem for a circular tube, to a rectangular microchannel. The same formula for the relation between nondimensional time and interface position is obtained as for a circular tube. We examined rectangular microchannels with several sizes (about 50 to 100 microm square) of glass capillaries and 85 x 68 microm and 75 x 45 microm polydimethylsiloxane (PDMS) microchannels fabricated by photolithography technique, respectively. We observed movement of the gas-liquid interface position and compared it to the dimensionless relation. We obtained the value of a dimensionless variable of driving force that is related to dynamic contact angles for glass-water, glass-ethanol, and PDMS-ethanol. Using this variable, interface motion can be predicted for any size of rectangular channels. PMID:15476786

Ichikawa, Naoki; Hosokawa, Kazuo; Maeda, Ryutaro

2004-12-01

191

Use of dynamically coated capillaries with added cyclodextrins for the analysis of opium using capillary electrophoresis  

Microsoft Academic Search

A rapid, precise, accurate, and robust method using capillary electrophoresis (CE) with dynamically coated capillaries for the analysis of the major opium alkaloids in opium is presented. Dynamic coating of the capillary surface is accomplished using a commercially available reagent kit (polycation coating followed by polyanion coating). The addition of dual cyclodextrins (hydroxypropyl-?-cyclodextrin and dimethyl-?-cyclodextrin) to the run buffer imparts

Ira S Lurie; Sini Panicker; Patrick A Hays; Agnes D Garcia; Bryan L Geer

2003-01-01

192

Tapers and restrictors for capillary electrochromatography and capillary electrochromatography-mass spectrometry  

Microsoft Academic Search

Tapered and narrow restrictor capillaries have been investigated for use in capillary electrochromatography (CEC) and have been shown to offer viable, more reproducible, alternatives to silica frits and may aid in suppression of bubble formation, a recognised problem in CEC. In addition, these capillaries have been coupled to mass spectrometry, especially for low-flow and nano-flow electrospray ionisation, where results have

G. A. Lord; D. B. Gordon; P. Myers; B. W. King

1997-01-01

193

21 CFR 864.6150 - Capillary blood collection tube.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Capillary blood collection tube. 864.6150 Section...Hematology Devices § 864.6150 Capillary blood collection tube. (a) Identification. A capillary blood collection tube is a plain or...

2011-04-01

194

21 CFR 864.6150 - Capillary blood collection tube.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Capillary blood collection tube. 864.6150 Section...Hematology Devices § 864.6150 Capillary blood collection tube. (a) Identification. A capillary blood collection tube is a plain or...

2014-04-01

195

21 CFR 864.6150 - Capillary blood collection tube.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Capillary blood collection tube. 864.6150 Section...Hematology Devices § 864.6150 Capillary blood collection tube. (a) Identification. A capillary blood collection tube is a plain or...

2012-04-01

196

21 CFR 864.6150 - Capillary blood collection tube.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Capillary blood collection tube. 864.6150 Section...Hematology Devices § 864.6150 Capillary blood collection tube. (a) Identification. A capillary blood collection tube is a plain or...

2013-04-01

197

21 CFR 864.6150 - Capillary blood collection tube.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Capillary blood collection tube. 864.6150 Section...Hematology Devices § 864.6150 Capillary blood collection tube. (a) Identification. A capillary blood collection tube is a plain or...

2010-04-01

198

Electromigration dispersion in Capillary Electrophoresis  

PubMed Central

In a previous paper (S. Ghosal and Z. Chen Bull. Math. Biol. 2010 72, pg. 2047) it was shown that the evolution of the solute concentration in capillary electrophoresis is described by a nonlinear wave equation that reduced to Burger’s equation if the nonlinearity was weak. It was assumed that only strong electrolytes (fully dissociated) were present. In the present paper it is shown that the same governing equation also describes the situation where the electrolytic buffer consists of a single weak acid (or base). A simple approximate formula is derived for the dimensionless peak variance which is shown to agree well with published experimental data. PMID:22147104

Chen, Zhen; Ghosal, Sandip

2012-01-01

199

Capillary electrophoresis for pharmaceutical analysis.  

PubMed

This chapter describes the application of capillary electrophoresis (CE) to pharmaceutical analysis. The areas of pharmaceutical analysis covered are enantiomer separation, analysis of small molecules such as amino acids or drug counter-ions, pharmaceutical assay, related substances determinations, and physiochemical measurements such as log P and pKa of compounds. The different electrophoretic modes available and their advantages for pharmaceutical analysis are described. Recent applications of CE for each subject area are tabulated with electrolyte details. Information on electrolyte choice and method optimization to obtain optimal separations is included. PMID:18392572

Marsh, Alex; Broderick, Margo; Altria, Kevin; Power, Joe; Donegan, Sheila; Clark, Brian

2008-01-01

200

High pressure pulsed capillary viscometry  

NASA Technical Reports Server (NTRS)

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.

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

1972-01-01

201

Sheathless interface for coupling capillary electrophoresis with mass spectrometry  

SciTech Connect

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.

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

2014-06-17

202

Guided Organization of ?-DNAs into Microring-Arrays from Liquid Capillary Microbridges  

NASA Astrophysics Data System (ADS)

Well-ordered, mesoscale ?-DNA ring-arrays have been successfully produced via controlled evaporative self-assembly with capillary actions in liquid capillary microbridges. The dimension of the ?-DNA microrings can be readily tuned by the choice of the PDMS molds. This approach opens a new avenue to utilize evaporative self-assembly as an alternative to conventional lithographic techniques for generating biomolecular patterned arrays in a simple, precise, and cost-effective manner. Using this facile and robust route, a great variety of biomaterials can easily and precisely organized into well-ordered ring arrays, which may have potential applications in functional scaffolds for cell and tissue growth, biosensors, etc.

Byun, Myunghwan; Hong, Suck Won; Cho, Jin-Woo; Lin, Zhiqun

2010-03-01

203

APPLICATIONS OF LASERS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Laser absorption waves in metal capillaries  

NASA Astrophysics Data System (ADS)

Experimental and numerical investigations were made of the propagation of laser absorption waves in metal capillaries subjected to CO2 laser pulses. The dependence of the velocity of propagation of a plasma front on the initial pressure of air in a capillary was determined. It was found that in a wide range of parameters the time needed for the formation of a layer of an optically opaque plasma was governed by the total energy of a pulse from the beginning from its action to the moment of appearance of screening and was not greatly affected by the pulse profile or by the gas pressure.

Anisimov, V. N.; Arutyunyan, R. V.; Bol'shov, Leonid A.; Kanevski?, M. F.; Kondrashov, V. V.; Krivoruchko, K. A.; Malyuta, D. D.; Reshetin, V. P.; Sebrant, A. Yu; Stepanova, M. A.

1987-07-01

204

Chocked flows in open capillary channels  

Microsoft Academic Search

Capillary systems provide a passive means to control fluids and are widely used for space craft fuel management. In the present study the forced liquid flow through an open capillary channel under low gravity conditions is investigated. Due to convective and viscous momentum transport the pressure along the flow path decreases and causes the free surface to bend inwards the

Joerg Klatte; U. Rosendahl; D. Haake; A. Grah; M. Dreyer

2007-01-01

205

Gravity Capillary Standing Water Waves Pietro Baldi  

E-print Network

Gravity Capillary Standing Water Waves Pietro Baldi Universit`a di Napoli Federico II Joint work with Thomas Alazard (ENS Paris) Pienza, 29 October 2014 Pietro Baldi Gravity Capillary Standing Water Waves Standing Water Waves #12;Preliminary discussion: interaction of progressive waves One gravity

Thomann, Laurent

206

Capillary flow properties of porous wicks  

Microsoft Academic Search

Results are presented for the capillary pressure versus saturation for square mesh screen wicks. The capillary pressure curves are shown to correlate well when cast in terms of the dimensionless Leverett function. Results of transient wicking rise tests are also presented. The transient saturation distributions are used to calculate the relative permeability of the partially saturated wick structures.

J. H. Ambrose; L. C. Chow; J. E. Beam

1988-01-01

207

Capillary Physiology and Drug Delivery in Central  

E-print Network

Capillary Physiology and Drug Delivery in Central Nervous System Lymphomas Peter C. Warnke, MD,1 drug delivery, we quantita- tively assessed pharmacokinetic factors in seven patients. The capillary the chemosensitivity of primary cen- tral nervous system lymphomas to water-soluble drugs could result from improved

Timmer, Jens

208

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

NASA Astrophysics Data System (ADS)

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.

Gharbi, Oussama; Blunt, Martin J.

2012-12-01

209

Effects on wettability by surfactant accumulation\\/depletion in bulk polydimethylsiloxane (PDMS)  

Microsoft Academic Search

Polydimethylsiloxane (PDMS) is an appealing silicone elastomer as a base material for microfluidic biomedical applications. Its ability to easily cross-link as well as its favorable physical and chemical properties has enabled a large number of micro- and nano-cast applications. However, PDMS’ hydrophobic surface can be problematic. Two methods presented here address the wettability of PDMS by accumulating or depleting surfactant

Jeonggi Seo; Luke P. Lee

2006-01-01

210

Influence of surface modification on wettability and surface energy characteristics of pharmaceutical excipient powders.  

PubMed

Influence of surface modification on wettability and surface energy characteristics of three micron size pharmaceutical excipient powders was studied using hydrophilic and hydrophobic grades of nano-silica. The wetting behavior assessed from contact angle measurements using sessile drop and liquid penetration (Washburn) methods revealed that both techniques showed similar wettability characteristics for all powders depending on the hydrophilic or hydrophobic nature of nano-coating achieved. The polar (?s(p)) and dispersive (?s(d)) components of surface energies determined using extended Fowke's equation with contact angle data from sessile drop method and inverse gas chromatography (IGC) at infinite dilution suggested a general trend of decrease in ?s(d) for all the surface modified powders due to passivation of most active sites on the surface. However, depending on the nature of the functional groups present in nano-silica, ?s(p) was found to be either higher or lower for hydrophilic or hydrophobic coating respectively. Results show that wettability increases with increasing ?s(p). Both the techniques of surface energy determination provided comparable and similar trends in ?s(p) and ?s(d) components of surface energies for all excipients. The study also successfully demonstrated that surface wettability and energetics of powders can be modified by varying the level of surface coating. PMID:25195729

Karde, Vikram; Ghoroi, Chinmay

2014-11-20

211

Cellular Behavior of Human Adipose-Derived Stem Cells on Wettable Gradient Polyethylene Surfaces  

PubMed Central

Appropriate surface wettability and roughness of biomaterials is an important factor in cell attachment and proliferation. In this study, we investigated the correlation between surface wettability and roughness, and biological response in human adipose-derived stem cells (hADSCs). We prepared wettable and rough gradient polyethylene (PE) surfaces by increasing the power of a radio frequency corona discharge apparatus with knife-type electrodes over a moving sample bed. The PE changed gradually from hydrophobic and smooth surfaces to hydrophilic (water contact angle, 90º to ~50º) and rough (80 to ~120 nm) surfaces as the power increased. We found that hADSCs adhered better to highly hydrophilic and rough surfaces and showed broadly stretched morphology compared with that on hydrophobic and smooth surfaces. The proliferation of hADSCs on hydrophilic and rough surfaces was also higher than that on hydrophobic and smooth surfaces. Furthermore, integrin beta 1 gene expression, an indicator of attachment, and heat shock protein 70 gene expression were high on hydrophobic and smooth surfaces. These results indicate that the cellular behavior of hADSCs on gradient surface depends on surface properties, wettability and roughness. PMID:24477265

Ahn, Hyun Hee; Lee, Il Woo; Lee, Hai Bang; Kim, Moon Suk

2014-01-01

212

Investigation of wettability by NMR microscopy and spin-lattice relaxation  

SciTech Connect

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.

Doughty, D.A.; Tomutsa, Liviu

1993-11-01

213

Frontispiece: Wettability-Regulated Extracellular Electron Transfer from the Living Organism of Shewanella loihica PV-4.  

PubMed

Electron Transfer Extracellular electron transfer from living microbes can be regulated by altering the surface wettability of the electrode. In their Communication on page?1446?ff., H. Liu, Y. Zhu, et?al. report that the electron transfer activity on a hydrophilic electrode is more than five times higher than that on a hydrophobic one. PMID:25612176

Ding, Chun-Mei; Lv, Mei-Ling; Zhu, Ying; Jiang, Lei; Liu, Huan

2015-01-26

214

Effect of Crude-Oil-Induced Wettability Changes on Oil Recovery  

Microsoft Academic Search

Displacements in strongly water-wet cores are compared with results of similar tests for a mixed wettability condition induced by a selected crude oil. Cores exposed to crude oil showed weakly water-wet imbibition behavior and 30 to 65% improvement in microscopic displacement efficiency. Other characteristics included clean breakthrough and low relative permeability to water at residual oil saturation. Flow visualization experiments

Norman Morrow; Hau Lim; Jill Ward

1986-01-01

215

Contact Lenses Wettability In Vitro: Effect of Surface-Active Ingredients  

PubMed Central

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

Lin, Meng C.; Svitova, Tatyana F.

2010-01-01

216

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 ...

217

Voltammetric detection for capillary electrophoresis.  

PubMed

Several approaches to implementing amperometric detection for capillary electrophoresis have been reported. This report describes the development of a voltammetric detector for CE. The detector is designed to minimize distortion of the voltammetry due to ohmic potential drop. This was accomplished by using a cast Nafion detection cell at the end of the separation capillary. The cast Nafion detection cell provided a low-dead-volume, low-resistance cell that minimized ohmic potential drop and peak band broadening. The ability to detect the current due to oxidation of analytes superimposed on a large background current was also improved. A dynamic background subtraction scheme was used in which a second working electrode, positioned in the electrochemical cell but outside of the detection cell, was used to compensate for the background current in real time. The output of the compensating working electrode was subtracted from the output of the detecting working electrode prior to analog-to-digital conversion. Postexperimental digital background subtraction was also implemented. This approach provided optimal elimination of the background current with maximal detection of the analytical signal. The voltammetric detector developed produced high-quality voltammetric response of analytes with injected concentrations as low as 0.20 microM. The system was evaluated by obtaining CE voltammograms of a mixture of eight test phenolic acids. PMID:9253250

Park, S; McGrath, M J; Smyth, M R; Diamond, D; Lunte, C E

1997-08-01

218

Cryogenic Capillary Screen Heat Entrapment  

NASA Technical Reports Server (NTRS)

Cryogenic liquid acquisition devices (LADs) for space-based propulsion interface directly with the feed system, which can be a significant heat leak source. Further, the accumulation of thermal energy within LAD channels can lead to the loss of sub-cooled propellant conditions and result in feed system cavitation during propellant outflow. Therefore, the fundamental question addressed by this program was: "To what degree is natural convection in a cryogenic liquid constrained by the capillary screen meshes envisioned for LADs.?"Testing was first conducted with water as the test fluid, followed by LN2 tests. In either case, the basic experimental approach was to heat the bottom of a cylindrical column of test fluid to establish stratification patterns measured by temperature sensors located above and below a horizontal screen barrier position. Experimentation was performed without barriers, with screens, and with a solid barrier. The two screen meshes tested were those typically used by LAD designers, "200x1400" and "325x2300", both with Twill Dutch Weave. Upon consideration of both the water and LN2 data it was concluded that heat transfer across the screen meshes was dependent upon barrier thermal conductivity and that the capillary screen meshes were impervious to natural convection currents.

Bolshinskiy, L.G.; Hastings, L.J.; Stathman, G.

2007-01-01

219

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

SciTech Connect

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.

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

1993-09-01

220

Two-dimensional capillary electrophoresis: capillary isoelectric focusing and capillary zone electrophoresis with laser-induced fluorescence detection  

PubMed Central

Capillary isoelectric focusing and capillary zone electrophoresis are coupled with laser-induced fluorescence detection to create an ultrasensitive two-dimensional separation method for proteins. In this method, two capillaries are joined through a buffer filled interface. Separate power supplies control the potential at the injection end of the first capillary and at the interface; the detector is held at ground potential. Proteins are labeled with the fluorogenic reagent Chromeo P503, which preserves the isoelectric point of the labeled protein. The labeled proteins were mixed with ampholytes and injected into the first dimension capillary. A focusing step was performed with the injection end of the capillary at high pH and the interface at low pH. To mobilize components, the interface was filled with a high pH buffer, which was compatible with the second dimension separation. A fraction was transferred to the second dimension capillary for separation. The process of fraction transfer and second dimension separation was repeated two dozen times. The separation produced a spot capacity of 125. PMID:20603830

Dickerson, Jane A.; Ramsay, Lauren M.; Dada, Oluwatosin O.; Cermak, Nathan

2011-01-01

221

New concept for coal wettability evaluation and modulation. Technical progress report, January 1, 1994--March 31, 1994  

SciTech Connect

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.

Hu, W.

1994-05-01

222

Excitation of Capillary Waves in Strongly Absorbing Liquids by a Modulated Laser Beam  

NASA Astrophysics Data System (ADS)

Several mechanisms for the excitation of capillary waves and for the development of the average deformation of a liquid surface under the action of a modulated laser beam are considered. The amplitude of the capillary wave in a strongly absorbing solution of the dye LDS 751 in ethylene glycol is experimentally studied as a function of laser intensity. Consecutive changes in the predominant mechanism of the excitation with increasing laser intensity are observed and described. At low laser intensities the mechanism connected with the creation of a surface tension gradient prevails. This mechanism becomes nonlinear with increasing influence of the convective motion. In addition, pressure pulsations of the convective flow start to contribute significantly to the generation process. The resonances of capillary waves in a cylindrical container are also investigated and used for determining the surface tension and viscosity of the liquid.

Kolomenskii, Alexandre A.; Schuessler, Hans A.

1999-10-01

223

Copolymers For Capillary Gel Electrophoresis  

DOEpatents

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.

Liu, Changsheng (State College, PA); Li, Qingbo (State College, PA)

2005-08-09

224

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

225

Capillary-based x-ray filters  

SciTech Connect

The results of computer simulation and experimental investigation of different capillary-based filters are presented. Filters with multiple reflections in polycapillaries, filters with single reflections, combinations of capillary structures with crystals and conventional x-ray absorption filters are considered. Capillary-based x-ray filters effectively suppress the high-energy part of radiation while the supplementary elements suppress the soft part of spectrum. The possibility of application of such filters in laboratory set-up and in synchrotron beam line is discussed.

Arkadiev, V.A. [Inst. fuer Geraetebau GmbH, Berlin (Germany); [Kurchatov Inst., Moscow (Russian Federation); Bzhaumikhov, A.A.; Gorny, H.E.; Langhoff, N.; Schmalz, J. [Inst. fuer Geraetebau GmbH, Berlin (Germany)

1996-12-31

226

Capillary force repels coffee-ring effect  

NASA Astrophysics Data System (ADS)

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.

Weon, Byung Mook; Je, Jung Ho

2010-07-01

227

Plasma of capillary discharge of low pressure  

NASA Astrophysics Data System (ADS)

Ionization equilibrium is considered for a capillary plasma of low pressure within a scheme where a tail of the energy distribution function of electrons at energies above the atom excitation energy includes a small portion of electrons. The kinetics of a gas discharge plasma in strong fields is developed and allows one to determine the drift velocity of electrons and other parameters of a capillary plasma. The results are applied to a capillary plasma of helium and argon. The analysis leads to the optimal shape of the gas discharge chamber for the formation of a plasma torch with fast electrons.

Smirnov, B. M.; Tereshonok, D. V.

2014-02-01

228

Micromechanism linear actuator with capillary force sealing  

DOEpatents

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.

Sniegowski, Jeffry J. (Albuquerque, NM)

1997-01-01

229

Analysis of Simple Carbohydrates by Capillary Electrophoresis and Capillary Electrophoresis–Mass Spectrometry  

Microsoft Academic Search

\\u000a An overview of the application of capillary electrophoresis and ­capillary electrophoresis–mass spectrometry in the analysis\\u000a of simple carbohydrates without any previous derivatization step is given. Besides electrolyte systems for ­carbohydrate separation,\\u000a detection techniques employed in capillary electrophoresis, such as ­spectrophotometric detection, electrochemical detection,\\u000a and mass spectrometric ­detection, are discussed, as are less common detection techniques. Thus, the chapter focuses on

Christian W. Klampfl; Markus Himmelsbach; Wolfgang Buchberger

230

PLUMAGE WETTABILITY OF THE AFRICAN DARTER ANHINGA MELANOGASTER COMPARED WITH THE DOUBLE-CRESTED CORMORANT PHALACROCORAX AURITUS  

Microsoft Academic Search

Rijke, A. M., Jesser, W. A. & Mahoney, S. A. 1989. Plumage wettability of the African Darter Anhinga melanogaster compared with the Double-crested Cormorant Phalacrocarax auritus. Ostrich 60:128-132.Darters emerge from water “dripping wet” but are able to become airborne without delay. Their plumage is, on the whole, three times more wettable than that of cormorants. We investigated the microscopic structure

Arie M. Rijke; William A. Jesser; Sheila A. Mahoney

1989-01-01

231

Micro-nano hybrid structures with manipulated wettability using a two-step silicon etching on a large area  

Microsoft Academic Search

Nanoscale surface manipulation technique to control the surface roughness and the wettability is a challenging field for performance\\u000a enhancement in boiling heat transfer. In this study, micro-nano hybrid structures (MNHS) with hierarchical geometries that\\u000a lead to maximizing of surface area, roughness, and wettability are developed for the boiling applications. MNHS structures\\u000a consist of micropillars or microcavities along with nanowires having

Beom Seok Kim; Sangwoo Shin; Seung Jae Shin; Kyung Min Kim; Hyung Hee Cho

2011-01-01

232

Influence of textural and wettability variations on predictions of DNAPL persistence and plume development in saturated porous media  

Microsoft Academic Search

Numerical simulations examine the migration, entrapment, and mass recovery behavior of DNAPLs in aquifer systems with coupled textural and wettability variations. Permeability fields of varying degrees of heterogeneity (i.e., differing ?ln(k)2) were generated with sequential Gaussian simulation, using geostatistical parameters derived from core grain size measurements in a sandy glacial outwash aquifer. Organic-wet mass fraction, a representative metric for wettability,

Thomas J. Phelan; Lawrence D. Lemke; Scott A. Bradford; Denis M. O'Carroll; Linda M. Abriola

2004-01-01

233

Upscaling capillary pressure-saturation curves in heterogeneous porous media  

Microsoft Academic Search

Numerical models of flow in the vadose zone require capillary pressure-saturation relationships for the grid blocks discretizing the medium. However, the scale of these grid blocks is generally much larger than the sample scale at which capillary pressure-saturation relationships are measured. This study investigates the upscaling of capillary curves under static conditions of capillary-gravity equilibrium. The upscaling of capillary curves

A. J. Desbarats

1995-01-01

234

Improved column preparation and performance in capillary electrochromatography.  

PubMed

Problems encountered in capillary electrochromatography, i.e. non-reproducible column manufacture, bubble formation during usage, short column lifetimes and limited choice of packing particles are addressed by the development of fritless or single-frit, internally tapered, segmented and dead-volume free coupled capillary columns. The Van Deemter plots measured demonstrate the performance of these high-quality capillaries which are suitable for capillary electrochromatography as well as for capillary high-performance liquid chromatographic applications. PMID:10961327

Rapp, E; Bayer, E

2000-07-28

235

Capillary Pressure - Mac OS 10.7  

NSDL National Science Digital Library

Computer program for Mac OS 10.7 to illustrate the vascular control of capillary hydrostatic pressure. Possible simulations include arteriolar vasoconstriction and dilation, venous obstruction, hypotension, reflex vasoconstriction, etc.

2004-10-01

236

Multistaged stokes injected Raman capillary waveguide amplifier  

DOEpatents

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.

Kurnit, Norman A. (Santa Fe, NM)

1980-01-01

237

Geometry and wetting of capillary folding  

E-print Network

Capillary forces are involved in a variety of natural phenomena, ranging from droplet breakup to the physics of clouds. The forces from surface tension can also be exploited in industrial applications provided the length ...

Lauga, Eric

238

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...

239

Effects of aqueous polymeric surfactants on silicone-hydrogel soft- contact-lens wettability and bacterial adhesion of Pseudomonas aeruginosa.  

PubMed

Prevention of Pseudomonas aeruginosa binding to soft-contact lenses (SCLs) may curtail sight-threatening microbial keratitis. Substrate surface wettability is known to modulate adhesion of P. aeruginosa. This study investigates the use of aqueous alkoxylate block co-polymer surfactants for enhanced wettability and antibacterial adhesion of SCLs under leaching conditions. Specifically, Pluronic(®) F127 (PF) and three ethylene oxide-butylene oxide (EOBO) surfactants were studied with four commercially available silicone-hydrogel contact lenses: Pure Vision™, Acuvue Advance™, Acuvue Oasys™ and O(2)Optix™. Dilute aqueous PF and EOBO surfactants impregnated all four soft-contact lenses, as demonstrated by surface-tension decline for leached surfactant. For PF surfactant, significant surface-wettability improvement upon rinsing occurred only after overnight leaching. EOBO surfactant showed a similar pattern with O(2)Optix™ lenses. EOBO-pretreated Pure Vision™ lenses, however, showed fast leaching and a significant change in surface energy towards improved wettability. Adhesion assays of P. aeruginosa displayed a small decrease in the binding rate of PAK bacteria for EOBO-pretreated Pure Vision™ lenses, but not for EOBO-pretreated O(2)Optix™ lenses. P. aeruginosa strain-PAO1 bacteria adhesion to all lenses was independent of surface wettability. Despite the ability of polymeric surfactants to lower advancing contact angles under leaching conditions, increased lens wettability is not a universal panacea for antifouling of soft-contact lenses. PMID:22456099

Tran, Victoria B; Sung, Ye Suel; Copley, Kendra; Radke, C J

2012-08-01

240

Boiling Point of Capillary-condensed Water  

Microsoft Academic Search

A CONSIDERABLE amount of experimental work on freezing-point depressions of capillary condensates has been reported in the literature in recent years1. Carman2 has given an account of a few more properties in which capillary-held liquids differ from the same materials in bulk conditions. Boiling points of condensates, however, do not appear to have been studied in detail. We have devised

M. L. Lakhanpal; B. R. Puri

1953-01-01

241

Capillary Electrophoresis Applied to Polysaccharide Characterization  

Microsoft Academic Search

\\u000a Capillary electrophoresis is a consolidated analytical approach for the structural characterization of polysaccharide mono-\\u000a and oligomer constituents, as demonstrated in this chapter, which surveys several applications of this technique on chemically\\u000a and enzymatically degraded polysaccharides, covering the last 10 to 12 years. Capillary electrophoresis is also demonstrated\\u000a to be highly reliable for determination of polysaccharides in biological samples, as it

Mila Toppazzini; Anna Coslovi; Sergio Paoletti

242

Capillary rise between planar surfaces  

NASA Astrophysics Data System (ADS)

Minimization of free energy is used to calculate the equilibrium vertical rise and meniscus shape of a liquid column between two closely spaced, parallel planar surfaces that are inert and immobile. States of minimum free energy are found using standard variational principles, which lead not only to an Euler-Lagrange differential equation for the meniscus shape and elevation, but also to the boundary conditions at the three-phase junction where the liquid meniscus intersects the solid walls. The analysis shows that the classical Young-Dupré equation for the thermodynamic contact angle is valid at the three-phase junction, as already shown for sessile drops with or without the influence of a gravitational field. Integration of the Euler-Lagrange equation shows that a generalized Laplace-Young (LY) equation first proposed by O’Brien, Craig, and Peyton [J. Colloid Interface Sci. 26, 500 (1968)] gives an exact prediction of the mean elevation of the meniscus at any wall separation, whereas the classical LY equation for the elevation of the midpoint of the meniscus is accurate only when the separation approaches zero or infinity. When both walls are identical, the meniscus is symmetric about the midpoint, and the midpoint elevation is a more traditional and convenient measure of capillary rise than the mean elevation. Therefore, for this symmetric system a different equation is fitted to numerical predictions of the midpoint elevation and is shown to give excellent agreement for contact angles between 15° and 160° and wall separations up to 30mm . When the walls have dissimilar surface properties, the meniscus generally assumes an asymmetric shape, and significant elevation of the liquid column can occur even when one of the walls has a contact angle significantly greater than 90°. The height of the capillary rise depends on the spacing between the walls and also on the difference in contact angles at the two surfaces. When the contact angle at one wall is greater than 90° but the contact angle at the other wall is less than 90°, the meniscus can have an inflection point separating a region of positive curvature from a region of negative curvature, the inflection point being pinned at zero height. However, this condition arises only when the spacing between the walls exceeds a threshold value that depends on the difference in contact angles.

Bullard, Jeffrey W.; Garboczi, Edward J.

2009-01-01

243

Tailoring the wettability of patterned silicon surfaces with dual-scale pillars: From hydrophilicity to superhydrophobicity  

NASA Astrophysics Data System (ADS)

Wettability tailoring of patterned silicon surface has great potential in fields producing integrated circuits, solar cells, sensors, detectors, and micro/nano electromechanical systems. The present paper presents a convenient yet effective method of combining reactive ion etching and catalyzed etching to prepare silicon surface with micro-nano dual-scale pillars. The experimental results indicate that the hydrophilic surface transformed to a superhydrophobic surface when micro-nano dual-scale pillars were formed. The surface preserved superhydrophobicity even when the geometric parameters of the micropillars were changed. Overhangs of water drops on steep micro-nano dual-scale pillars result in superhydrophobicity. This method offers a new way for tailoring the wettability of patterned silicon surfaces.

He, Yang; Jiang, Chengyu; Yin, Hengxu; Yuan, Weizheng

2011-06-01

244

Dynamical surface affinity of diphasic liquids as a probe of wettability of multimodal porous media  

NASA Astrophysics Data System (ADS)

We introduce a method for estimating the wettability of rock/oil/brine systems using noninvasive in situ nuclear magnetic relaxation dispersion. This technique scans over a large range of applied magnetic fields and yields unique information about the extent to which a fluid is dynamically correlated with a solid rock surface. Unlike conventional transverse relaxation studies, this approach is a direct probe of the dynamical surface affinity of fluids. To quantify these features we introduce a microscopic dynamical surface affinity index which measures the dynamical correlation (i.e., the microscopic wettability) between the diffusive fluid and the fixed paramagnetic relaxation sources at the pore surfaces. We apply this method to carbonate reservoir rocks which are known to hold about two thirds of the world’s oil reserves. Although this nondestructive method concerns here an application to rocks, it could be generalized as an in situ liquid/surface affinity indicator for any multimodal porous medium including porous biological media.

Korb, J.-P.; Freiman, G.; Nicot, B.; Ligneul, P.

2009-12-01

245

Modulation of structure, morphology and wettability of polytetrafluoroethylene surface by low energy ion beam irradiation  

NASA Astrophysics Data System (ADS)

Polytetrafluoroethylene (PTFE) films were irradiated under vacuum with 3 keV Argon ions (Ar+) and fluences ranging from 0.5 × 1018 to 2 × 1018 ions/cm2. Ion induced PTFE surface modifications of structural, morphological and wettability nature were studied by means of Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy, atomic force microscopy and force spectroscopy, and contact angle measurements. FTIR analysis indicated defluorination of PTFE due to the rupture of C-C and C-F bonds. The values of droplet contact angle of the irradiated samples decreased gradually with the increasing ion flux, and were found to be very sensitive to the environmental humidity under which the measurements were made. The experimental results show that the surface chemical bond, morphology, and wettability of irradiated PTFE samples depend closely on the argon ion flux.

Atta, Ali; Fawzy, Yasser H. A.; Bek, Alpan; Abdel-Hamid, Hassan M.; El-Oker, Mohamed M.

2013-04-01

246

Regulating surface wettability of PEO/PLLA composite electrospun nanofibrous membrane for liquid phase filtration  

NASA Astrophysics Data System (ADS)

The PEO/PLLA composite nanofibrous membranes were prepared by electrospinning technique for liquid phase filtration application. In this experiment, PLLA homopolymer and PLLA-PEG copolymer were added into PEO solution to increase hydrophobicity of nanofibrous membrane surface. PLLA content was fixed at 30% by weight of total solid. Morphology and fiber diameter were characterized from scanning electron microscope (SEM) images. Fiber diameters of PEO/PLLA homopolymer and PEO/PLLA-PEG copolymer are 582+/-78 nm and 657+/-167 nm, respectively. Surface wettability property of PEO/PLLA composite nanofibrous membranes were measured by apparent water contact angle. The apparent water contact angle value of PEO/PLLA is 120°+/-2°, while PEO/PEG-b-PLLA is 99°+/-7°. The surface wettability of PEO/PLLA composite nanofibrous membranes can be modified by varying type of polymer.

Poonsit, Lalada; Sunthornvarabhas, Jackapon; Akira, Ito; Lertworasirikul, Amornrat

2014-06-01

247

Wettability-Regulated Extracellular Electron Transfer from the Living Organism of Shewanella loihica PV-4.  

PubMed

C-type cytochromes located on the outer membrane (OMCs) of genus Shewanella act as the main redox-active species to mediate extracellular electron transfer (EET) from the inside of the outer membrane to the external environment: the central challenge that must be met for successful EET. The redox states of OMCs play a crucial role in dictating the rate and extent of EET. Here, we report that the surface wettability of the electrodes strongly influences the EET activity of living organisms of Shewanella loihica PV-4 at a fixed external potential: the EET activity on a hydrophilic electrode is more than five times higher than that on a hydrophobic one. We propose that the redox state of OMCs varies significantly at electrodes with different wettability, resulting in different EET activities. PMID:25470810

Ding, Chun-Mei; Lv, Mei-Ling; Zhu, Ying; Jiang, Lei; Liu, Huan

2015-01-26

248

Correlation between sol-gel reactivity and wettability of silica films deposited on stainless steel  

NASA Astrophysics Data System (ADS)

Sol-gel silica films were deposited on 316L and 409 stainless steel substrates in order to investigate their wettability properties. These films were deposited by dip-coating varying some parameters of the sol-gel process, including the acid used in the synthesis, its concentration, and the heat treatment temperature. Water and oil contact angles were measured on the surfaces and discussed regarding the physico-chemical and morphological properties of the prepared films. The findings shown in this work allow correlating the wettability behavior of silica coatings with the sol-gel reactivity of sols prepared using various amounts of nitric acid. It was observed that the more reactive the silica sol, the more hydrophilic and oleophilic the prepared coating. The presence in the films of alkoxy residues due to an incomplete condensation reaction could decrease both the polar and dispersive components of the coating surface energy, respectively responsible for water and oil wetting.

Houmard, M.; Nunes, E. H. M.; Vasconcelos, D. C. L.; Berthomé, G.; Joud, J.-C.; Langlet, M.; Vasconcelos, W. L.

2014-01-01

249

Bundled capillary electrophoresis using microstructured fibres.  

PubMed

Joule heating, arising from the electric current passing through the capillary, causes many undesired effects in CE that ultimately result in band broadening. The use of narrow-bore capillaries helps to solve this problem as smaller cross-sectional area results in decreased Joule heating and the rate of heat dissipation is increased by the larger surface-to-volume ratio. Issues arising from such small capillaries, such as poor detection sensitivity, low loading capacity and high flow-induced backpressure (complicating capillary loading) can be avoided by using a bundle of small capillaries operating simultaneously that share buffer reservoirs. Microstructured fibres, originally designed as waveguides in the telecommunication industry, are essentially a bundle of parallel ?5??m id channels that extend the length of a fibre having otherwise similar dimensions to conventional CE capillaries. This work presents the use of microstructured fibres for CZE, taking advantage of their relatively high surface-to-volume ratio and the small individual size of each channel to effect highly efficient separations, particularly for dye-labelled peptides. PMID:21254119

Rogers, Benjamin; Gibson, Graham T T; Oleschuk, Richard D

2011-01-01

250

Multiple capillary biochemical analyzer with barrier member  

DOEpatents

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.

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

1996-01-01

251

Multiple capillary biochemical analyzer with barrier member  

DOEpatents

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.

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

1996-10-22

252

Structure and Wettability of Methoxy-Terminated Self-Assembled Monolayers on Gold  

Microsoft Academic Search

This manuscript describes the structure and wettability of self-assembled monolayers (SAMs) derived from the adsorption of a series of ˆ-methoxyalkanethiols (CH3O(CH2)nSH, where n ) 9-14) onto the surface of gold. Using ellipsometry, polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), and contact angle measurements, the interfacial properties were examined as a function of chain length. Analysis by ellipsometry revealed a progressive

Irmgard Wenzl; Chi Ming Yam; David Barriet; T. Randall Lee

2003-01-01

253

Effect of Microstructural Evolution on Wettability of Laser Coated Calcium Phosphate on Titanium Alloy  

SciTech Connect

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.

Kurella, Anil K [ORNL; Hu, Michael Z. [ORNL; Dahotre, Narendra B [ORNL

2008-01-01

254

Relationship between wettability and sizing degree of paper containing bulking agent  

Microsoft Academic Search

The addition of a bulking agent achieves the bulking of paper and increases the pore volume. In this study, the effect of\\u000a adding bulking agents with various alkyl chain lengths (C14, C18, and C22) on the bulk of paper, the sizing performance, and sheet wettability was evaluated. The bulking effect of a bulking agent\\u000a with a short alkyl chain length

Hailan Jin; Takayuki Okayama; Ryota Arai; Hajime Ohtani

2011-01-01

255

A photoresponsive wettability switch based on a dimethylamino calix[4]arene.  

PubMed

A photoreversible switch based on a photoresponsive host-guest system consisting of dimethylamino calix[4]arene L and 4-(phenylazo)benzoic acid (O) is reported. The host L exhibited selective binding and release of O on UV and visible irradiation at 450 and 365?nm, respectively. Moreover, the photoresponsive host-guest complex was applied as a photocontrolled wettability switch on a functional micro/nanostructured silicon surface, and is thus promising for applications in sensors and microfluidic devices. PMID:24820202

Zhang, Xiaoyan; Zhao, Haiyang; Tian, Demei; Deng, Hongtao; Li, Haibing

2014-07-21

256

Metal oxide-based nanoparticles: revealing their potential to enhance oil recovery in different wettability systems  

NASA Astrophysics Data System (ADS)

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.

Hendraningrat, Luky; Torsæter, Ole

2015-02-01

257

Metal oxide-based nanoparticles: revealing their potential to enhance oil recovery in different wettability systems  

NASA Astrophysics Data System (ADS)

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.

Hendraningrat, Luky; Torsæter, Ole

2014-03-01

258

Structural, surface wettability and antibacterial properties of HPMC-ZnO nanocomposite  

SciTech Connect

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.

Rao, B. Lakshmeesha; Asha, S.; Madhukumar, R.; Latha, S.; Gowda, Mahadeva; Shetty, G. Rajesha; Sangappa, E-mail: syhalabhavi@yahoo.co.in [Department of Studies in Physics, Mangalore University, Mangalagangotri - 574199 (India); Chandra, K. Sharath; Naik, Prashantha [Department of Biosciences, Mangalore University, Mangalagangotri - 574199 (India)

2014-04-24

259

Evaporation of Picolitre Droplets on Surfaces with a Range of Wettabilities and Thermal Conductivities  

E-print Network

Talbot, E.L., Berson, A., Brown, P.S. and Bain, C.D., Submitted to Physical Review E, 'Evaporation of Picolitre Droplets on Surfaces with a Range of Wettabilities and Thermal Conductivities' (accepted) Evaporation of Picolitre Droplets on Surfaces... , Durham, DH1 3LE, United Kingdom (Dated: June 8, 2012) The evaporation of picolitre water and ethanol droplets generated by Drop-on-Demand inkjet printing was investigated on substrates with apparent contact angles between 10? and 135? and thermal...

Talbot, E.L.; Berson, A.; Brown, P.S.; Bain, C.D.

2012-01-01

260

New concept for coal wettability evaluation and modulation. Technical progress report, April 1--June 30, 1995  

SciTech Connect

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.

Hu, W.

1996-05-01

261

Interfacial dynamics of two immiscible fluids in spatially periodic porous media: The role of substrate wettability  

NASA Astrophysics Data System (ADS)

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.

Mondal, Pranab Kumar; DasGupta, Debabrata; Chakraborty, Suman

2014-07-01

262

Substrate material affects wettability of surfaces coated and sintered with silica nanoparticles  

NASA Astrophysics Data System (ADS)

Silica nanoparticles coating and sintering is a widely-used approach for creating hydrophobic and superhydrophobic surfaces. The role of substrate material in this process, however, has not been thoroughly investigated. In this work, the role of substrate material is examined by measuring surface wettability of three different substrate materials (glass, polyimide and copper) under systematically varied conditions. These surfaces are modulated from hydrophilic (water contact angle (WCA) < 90°) to superhydrophobic (WCA > 150°) by coating and sintering silica nanoparticles, followed by assembling a layer of fluorine compound. Static WCA characterization shows that surface wettability is not solely dependent on the concentration of the coating colloidal, but is also on the substrate material. In particular, copper substrate exhibits a larger WCA than glass and polyimide substrates. Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS) and Atomic Force Microscopy (AFM) characterizations show that the substrate material-dependent wettability is attributed to thermal-induced nanostructures on the copper surface, which contributes to the hierarchical micro-/nano- topography. This finding is important for designing hydrophobic/superhydrophobic surfaces comprised of different materials, especially those that would experience thermal cycles in surface functionalization and subsequent use.

Wei, Kang; Zeng, Hansong; Zhao, Yi

2013-05-01

263

Surface energy engineering for tunable wettability through controlled synthesis of MoS2.  

PubMed

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

Gaur, Anand P S; Sahoo, Satyaprakash; Ahmadi, Majid; Dash, Saroj P; Guinel, Maxime J-F; Katiyar, Ram S

2014-08-13

264

Morphing and vectoring impacting droplets by means of wettability-engineered surfaces.  

PubMed

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

Schutzius, Thomas M; Graeber, Gustav; Elsharkawy, Mohamed; Oreluk, James; Megaridis, Constantine M

2014-01-01

265

Wettability control of BeO surfaces by alpha-irradiation-induced nuclear transmutation  

NASA Astrophysics Data System (ADS)

A simple method to control the wettability of BeO surfaces is developed on the base of alpha irradiation. In this research, BeO disks were irradiated with an alpha beam under conditions of ?25 MeV in alpha particle energy and ?315 nA/cm2 in beam current density. After the alpha irradiation, changes in morphology and chemical composition of BeO surfaces were analyzed using a field emission scanning electron microscopy and X-ray photoelectron spectroscopy. The wettability of pristine and alpha-irradiated BeO surfaces was analyzed by measuring water contact angles (CAs). The result of analysis indicated that C and F atoms were produced by the alpha irradiation. 12C atoms were mainly produced by (?, n) nuclear reaction when 9Be atoms collide with energetic alpha particles. On the other hand, 19F atoms were mostly created by (?, n) reaction and following ?+ decay when 16O atoms collide with alpha particles. Moreover, CF2 functional groups, which provide hydrophobic property, were formed by the combination of produced C and F atoms. The amount of CF2 functional groups produced on the surface increased as the fluence increased while no significant change in the surface roughness was observed. Accordingly, the CA of alpha-irradiated BeO surfaces gradually increased as the fluence increased. In conclusion, the wettability of BeO surfaces could be easily and precisely controlled by the alpha irradiation, from hydrophilicity to hydrophobicity.

Lee, Eun Je; Hur, Min Goo; Kong, Young Bae; Son, Jeong Mun; Park, Yong Dae; Park, Jeong Hoon; Yang, Seung Dae

2014-08-01

266

Enhancing the effect of the nanofiber network structure on thermoresponsive wettability switching.  

PubMed

This letter reports the enhancing effects of a nanofiber network structure on stimuli-responsive wettability switching. Thermoresponsive coatings composed of nanofibers were prepared by electrospinning from thermoresponsive polymer poly(N-isopropylacrylamide) (PNIPAAm). The nanofiber coatings showed a large amplitude of thermoresponsive change in the wettability from hydrophilic to hydrophobic states compared to a smooth cast film. In particular, the combination of the surface chemistry and unique topology of the electrospun nanofiber coatings enables a transition from the Wenzel state to the metastable Cassie-Baxter state with an increase in temperature and consequently an enhanced amplitude of change in the water contact angles: the apparent contact angle differences between 25 and 50 °C are ??*(25-50 °C )= 108 and 10° for the nanofiber coatings with a diameter of 830 nm and a smooth cast film, respectively. The fabrication of the 3D nanofiber network structure by electrospinning from stimuli-responsive materials is a promising option for highly responsive surfaces in wettability. PMID:22098173

Konosu, Yuichi; Matsumoto, Hidetoshi; Tsuboi, Kazuma; Minagawa, Mie; Tanioka, Akihiko

2011-12-20

267

Wettability of brazing alloys on molybdenum and TZM (Mo-Ti-Zr alloy)  

SciTech Connect

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.

McDonald, M.M.; Keller, D.L.; Heiple, C.R.; Hofmann, W.E.

1988-01-01

268

Controlling wettability and hydrophobicity of organoclays modified with quaternary ammonium surfactants.  

PubMed

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

Shah, Kinjal J; Mishra, Manish Kumar; Shukla, Atindra D; Imae, Toyoko; Shah, Dinesh O

2013-10-01

269

Morphing and vectoring impacting droplets by means of wettability-engineered surfaces  

PubMed Central

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

Schutzius, Thomas M.; Graeber, Gustav; Elsharkawy, Mohamed; Oreluk, James; Megaridis, Constantine M.

2014-01-01

270

Capillary fracture of soft gels  

NASA Astrophysics Data System (ADS)

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?t3/4. 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.

Bostwick, Joshua B.; Daniels, Karen E.

2013-10-01

271

Nonlinear waves in capillary electrophoresis  

PubMed Central

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

Ghosal, Sandip; Chen, Zhen

2011-01-01

272

OCT methods for capillary velocimetry  

PubMed Central

To date, two main categories of OCT techniques have been described for imaging hemodynamics: Doppler OCT and OCT angiography. Doppler OCT can measure axial velocity profiles and flow in arteries and veins, while OCT angiography can determine vascular morphology, tone, and presence or absence of red blood cell (RBC) perfusion. However, neither method can quantify RBC velocity in capillaries, where RBC flow is typically transverse to the probe beam and single-file. Here, we describe new methods that potentially address these limitations. Firstly, we describe a complex-valued OCT signal in terms of a static scattering component, dynamic scattering component, and noise. Secondly, we propose that the time scale of random fluctuations in the dynamic scattering component are related to red blood cell velocity. Analysis was performed along the slow axis of repeated B-scans to parallelize measurements. We correlate our purported velocity measurements against two-photon microscopy measurements of RBC velocity, and investigate changes during hypercapnia. Finally, we image the ischemic stroke penumbra during distal middle cerebral artery occlusion (dMCAO), where OCT velocimetry methods provide additional insight that is not afforded by either Doppler OCT or OCT angiography. PMID:22435106

Srinivasan, Vivek J.; Radhakrishnan, Harsha; Lo, Eng H.; Mandeville, Emiri T.; Jiang, James Y.; Barry, Scott; Cable, Alex E.

2012-01-01

273

N2 and CO2 capillary breakthrough experiments on Opalinus Clay  

NASA Astrophysics Data System (ADS)

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, 45°C). 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 m², 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 m² to 7E-24m². 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.

Amann, Alexandra; Busch, Andreas; Krooss, Bernhard M.

2013-04-01

274

Determination of chlorhexidine digluconate and polyhexamethylene biguanide in eye drops by capillary electrophoresis with contactless conductivity detection  

Microsoft Academic Search

Polyhexamethylene biguanide hydrochloride (PHMB-HCl) and chlorhexidine digluconate (CHG) are cationic disinfectants widely used in aqueous personal products such as eye drops, lotions and creams. The antiseptics belong to the biguanide group, which are cationic substances well known for their effective action against microbial infection. In this work, capillary electrophoresis combined with contactless conductivity detection was used to determinate these substances

Eva M. Abad-Villar; Susanne F. Etter; Michael A. Thiel; Peter C. Hauser

2006-01-01

275

Modeling the effect of surface forces on the equilibrium liquid profile of a capillary meniscus.  

PubMed

The equilibrium profile of a capillary meniscus formed under combined action of disjoining/conjoining and capillarity pressures is investigated. Attention is focused on the shape of a transition zone between a spherical meniscus and a thin liquid film in front of the meniscus. The Poisson-Boltzmann equation is used for calculations of electrostatic contribution to the disjoining/conjoining pressure and the liquid shape inside the transition zone. Both complete and partial wetting conditions are investigated. PMID:24998938

Kuchin, Igor V; Matar, Omar K; Craster, Richard V; Starov, Victor M

2014-08-28

276

Critical Velocities in Open Capillary Flow  

NASA Technical Reports Server (NTRS)

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.

Dreyer, Michael; Langbein, Dieter; Rath, Hans J.

1996-01-01

277

Capillary adhesion at the nanometer scale  

NASA Astrophysics Data System (ADS)

Molecular dynamics simulations are used to study the capillary adhesion from a nonvolatile liquid meniscus between a spherical tip and a flat substrate. The atomic structure of the tip, the tip radius, the contact angles of the liquid on the two surfaces, and the volume of the liquid bridge are varied. The capillary force between the tip and substrate is calculated as a function of their separation h. The force agrees with continuum predictions based on macroscopic theory for h down to ˜5 to 10 nm. At smaller h, the force tends to be less attractive than predicted and has strong oscillations. This oscillatory component of the capillary force is completely missed in the macroscopic theory, which only includes contributions from the surface tension around the circumference of the meniscus and the pressure difference over the cross section of the meniscus. The oscillation is found to be due to molecular layering of the liquid confined in the narrow gap between the tip and substrate. This effect is most pronounced for large tip radii and/or smooth surfaces. The other two components considered by the macroscopic theory are also identified. The surface tension term, as well as the meniscus shape, is accurately described by the macroscopic theory for h down to ˜1 nm, but the capillary pressure term is always more positive than the corresponding continuum result. This shift in the capillary pressure reduces the average adhesion by a factor as large as 2 from its continuum value and is found to be due to an anisotropy in the pressure tensor. The component in the plane of the substrate is consistent with the capillary pressure predicted by the macroscopic theory (i.e., the Young-Laplace equation), but the normal pressure that determines the capillary force is always more positive than the continuum counterpart.

Cheng, Shengfeng; Robbins, Mark O.

2014-06-01

278

Capillary Adhesion at the Nanometer Scale  

E-print Network

Molecular dynamics simulations are used to study the capillary adhesion from a nonvolatile liquid meniscus between a spherical tip and a flat substrate. The atomic structure of the tip, the tip radius, the contact angles of the liquid on the two surfaces, and the volume of the liquid bridge are varied. The capillary force between the tip and substrate is calculated as a function of their separation h. The force agrees with continuum predictions for h down to ~ 5 to 10nm. At smaller h, the force tends to be less attractive than predicted and has strong oscillations. This oscillatory component of the capillary force is completely missed in the continuum theory, which only includes contributions from the surface tension around the circumference of the meniscus and the pressure difference over the cross section of the meniscus. The oscillation is found to be due to molecular layering of the liquid confined in the narrow gap between the tip and substrate. This effect is most pronounced for large tip radii and/or smooth surfaces. The other two components considered by the continuum theory are also identified. The surface tension term, as well as the meniscus shape, is accurately described by the continuum prediction for h down to ~ 1nm, but the capillary pressure term is always more positive than the corresponding continuum result. This shift in the capillary pressure reduces the average adhesion by a factor as large as 2 from its continuum value and is found to be due to an anisotropy in the pressure tensor. The cross-sectional component is consistent with the capillary pressure predicted by the continuum theory (i.e., the Young-Laplace equation), but the normal pressure that determines the capillary force is always more positive than the continuum counterpart.

Shengfeng Cheng; Mark O. Robbins

2014-03-18

279

High speed and reproducible analysis of nitrosamines by capillary electrophoresis with a sulfonated capillary.  

PubMed

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

Taga, Atsushi; Nishi, Tomoko; Honda, Yoshitaka; Sato, Atsushi; Terashima, Hiroyuki; Suzuki, Kentaro; Kodama, Shuji; Boki, Keito

2007-01-01

280

Novel insights into capillary vessel basement membrane damage by snake venom hemorrhagic metalloproteinases: A biochemical and immunohistochemical study  

Microsoft Academic Search

The hemorrhagic activity characteristic of viperid snake envenomations is due to the action of venom metalloproteinases (SVMPs) on the capillary vessel basement membrane (BM). This study compared the action of two SVMPs on BM in vitro (degradation of Matrigel) and in vivo (immunohistochemical assessment of BM markers in mouse gastrocnemius muscle). SVMPs BaP1 (belonging to the P-I class) and jararhagin

Teresa Escalante; John Shannon; Ana M. Moura-da-Silva; José María Gutiérrez; Jay W. Fox

2006-01-01

281

Choosing Actions  

PubMed Central

Actions that are chosen have properties that distinguish them from actions that are not. Of the nearly infinite possible actions that can achieve any given task, many of the unchosen actions are irrelevant, incorrect, or inappropriate. Others are relevant, correct, or appropriate but are disfavored for other reasons. Our research focuses on the question of what distinguishes actions that are chosen from actions that are possible but are not. We review studies that use simple preference methods to identify factors that contribute to action choices, especially for object-manipulation tasks. We can determine which factors are especially important through simple behavioral experiments. PMID:23761769

Rosenbaum, David A.; Chapman, Kate M.; Coelho, Chase J.; Gong, Lanyun; Studenka, Breanna E.

2013-01-01

282

Capillary Flow of Oil in a Single Foam Microchannel  

E-print Network

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.

Keyvan Piroird; Élise Lorenceau

2013-05-23

283

High performance of cyclic olefin copolymer-based capillary electrophoretic chips.  

PubMed

This paper demonstrates a simple, one step, and low cost surface modification technique for producing cyclic olefin copolymer (COC) polymer-based microcapillary electrophoresis chips consisting highly hemocompatible microchannels by UV-photografting with N-vinylpyrrolidone (NVP) monomer. An optimal condition has been identified to achieve the best surface grafting process. It has been found that this surface treatment enables extremely high surface wettability, hemocompatibility, and bond strength to the microchannels. The surface grafting was confirmed by attenuated total reflection Fourier transform-infrared spectroscopic (ATR-FTIR) study. In vitro protein adsorption using fluorescent labeled bovine serum albumin (FITC-BSA) into the COC microchannel results indicates that the modified chips have excellent protein resistance ability because of the increase of surface hydrophilicity. Hence, the modified chips showed fast, reproducible and high efficient separations of proteins (up to 51,000 theoretical plates per meter). Moreover, this surface modification process show no loss in the optical transparency to the modified microchannel surfaces: an important requirement for real capillary electrophoresis since the fluorescent intensity is directly related to the amount of adsorbed protein on the surface. Therefore, we believe that this simple and promising route of surface modification could be very useful for developing high performance COC microfluidic devices for the separation of proteins, amino acids, and other biomolecules. PMID:23748936

Roy, Sunanda; Das, Tanya; Yue, C Y

2013-06-26

284

Capillary liquid chromatography using laser-based and mass spectrometric detection. [Capillary zone electrophoresis (CZE); micellar electrokinetic capillary kchromatography (MECC)  

SciTech Connect

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)

Sepaniak, M.J.; Cook, K.D.

1992-01-01

285

Capillaries in the epithelium of pterygium  

PubMed Central

AIM—To present new morphological observations of intraepithelial capillaries in pterygium and to provide some explanations for this phenomenon.?METHODS—The ultrastructural features of pterygia from 26 patients were examined. Surgically excised tissue was processed for conventional light and transmission electron microscopy.?RESULTS—Individual capillaries within the epithelium of the anterior half towards the head of pterygia were identified in 11 specimens out of 26 pterygia examined (42.3%). The perivascular connective tissue of the intraepithelial capillaries contained fibroblasts, collagen fibrils, and elastin-like material. Epithelial cells surrounding these capillaries showed defects in the basal lamina in contrast with the continuous basal lamina of the endothelium. In the intercellular space of the epithelium an amorphous substance, occasional fibroblast processes, and collagen fibrils were frequently observed.?CONCLUSION—Capillaries in the epithelium of pterygia are rare, but not exceptional. The ingrowth of these vessels from the stroma into the epithelium can be interpreted as a reaction to hypoxia or deficiency of any other substance transported via the bloodstream. Apparently, the perivascular connective tissue can be used by ingrowing fibroblasts as a migration pathway. The migrating fibroblasts appear to use the defects of the epithelial basal lamina (whether partially or complete) in order to reach the intercellular space. It is possible that collagen fibrils in the epithelial intercellular space have been laid down by fibroblasts which contribute to the pathological dedifferentiation of the conjunctival epithelium.?? Keywords: pterygium; ultrastructure; epithelium; blood vessels PMID:9536887

Seifert, P.; Sekundo, W.

1998-01-01

286

Restructuring and aging in a capillary suspension  

E-print Network

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.

Erin Koos; Wolfgang Kannowade; Norbert Willenbacher

2014-10-07

287

Electrical resistance of muscle capillary endothelium.  

PubMed

A recently developed technique for in vivo determination of the electrical resistance of vascular endothelium in microvessels was applied to the vessels in a thin frog muscle, m. cutaneus pectoris. The technique consists of injection of current via a glass micropipette into a capillary and measurement of the resulting intra- and extravascular potential profiles with another micropipette placed at various distances from the current source. The theory of Peskoff and Eisenberg (1974) was used to handle the problems arising from distributed extravascular resistances and was experimentally shown to describe the external field satisfactorily. With this extension of one-dimensional cable theory the specific electrical resistance of arterial microvessels was 33 omega cm2 and of venous capillaries 23 omega cm2. The "length constants" were 135 and 112 micrometers, respectively. If results from arterial and venous vessels are taken together, the ionic permeabilities at 20 degrees C were PNa = 3.9 X 10(-5) cm X s-1, PK = 5.7 X 10(-5) cm X s-1, PCl = 5.9 X 10(-5) cm X s-1 and PHCO3 = 3.4 X 10(-5) cm X s-1. These figures agree with figures for capillary permeability obtained in tracer experiments on whole muscle. The study bridges a gap between single capillary and whole organ techniques with the conclusion that the two different approaches lead to similar results in muscle capillaries. PMID:6601500

Olesen, S P; Crone, C

1983-04-01

288

Modeling aerobic biodegradation in the capillary fringe.  

PubMed

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

Luo, Jian; Kurt, Zohre; Hou, Deyi; Spain, Jim C

2015-02-01

289

Permeability of muscle capillaries to microperoxidase  

PubMed Central

In this study we attempted to identify a morphologic counterpart of the small pore of muscle capillaries. The existence of such a pore has been postulated by physiologists to explain the permeability of muscle capillaries to small macromolecules. We injected mice intravenously with microperoxidase (MP) and fixed specimens of diaphragm at intervals of 0-250 s after the injection to localize the tracer by electron microscopy. The small size of MP (1,900 mol wt and 20 A molecular diameter [MD]) ensures its ready passage through the small pore since the latter is thought to be either a cylindrical channel 90 A in diameter or a slit 55 A wide. MP appears in the pericapillary interstitium within 30 s of initiation of its intravenous injection. The patterns of localization of MP observed within clefts between adjacent capillary endothelial cells indicate that some endothelial junctions are permeable to this tracer. Although small vesicles transfer MP across the endothelium, we do not believe that the vesicles transfer substantial amounts of MP into the pericapillary interstitium. We did not obtain evidence that MP crosses the endothelium of capillaries through channels formed either by a single vesicle or by a series of linked vesicles opening simultaneously at both surfaces of the endothelial cell. From our observations we conclude that some endothelial junctions of capillaries are permeable to MP, and that these permeable junctions are a plausible morphologic counterpart of the small pore. PMID:10605442

Wissig, S. L.; Williams, M. C.

1978-01-01

290

Micro-scale electrochemically actuated capillary lens  

NASA Astrophysics Data System (ADS)

This work demonstrates a variable-focus micro-capillary lens device fabricated using MEMS technology. The lens actuation principle is based on electrochemically-induced changes in surface tension of the redox surfactant solution that makes up the lens body. The changes in surface tension control the radius of curvature of the lens/air interface. The micro-capillary lens is obtained by filling with a water/surfactant solution of 100 micron diameter holes etched in a glass substrate. Electrodes are microfabricated adjacent to the air/liquid/solid contact line and used to individually address each capillary surface. Device micro-fabrication, testing of the focal lens changes, and time response will be presented.

Hwang, Wootaek; Ciuryla, Marcus; Hirsa, Amir; Borca-Tasciuc, Theodorian

2004-11-01

291

Extragingival pyogenic granuloma histologically mimicking capillary hemangioma  

PubMed Central

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

Dahiya, Ritu; Kathuria, Abhinav

2014-01-01

292

[Increased capillary vulnerability in diabetic retinopathy].  

PubMed

The retinal capillary network is isolated by Cogan and Kuwabara's method. During prolonged trypsinization the capillaries lose their endothelial cells and pericytes and are transformed into cell-free tubes consisting of basement membranes. This occurs earlier in patients with stage I or II retinopathy than in controls with normal carbohydrate metabolism and patients with stage I hypertension. Therefore, the intercellular junctions and the adhesion between endothelial cells and subendothelial basement lamella are more loosely structured in diabetics than normal subjects, and the cells do not resist the tryptic attack as well. The higher capillary vulnerability demonstrated in these experiments contributes to bleeding and exudation. Whether the local loss of cells in the microcirculation of diabetics occurs primarily in vivo or is only unmasked in vitro manifesting pre-existing cellular damage is discussed. PMID:3374013

Fuchs, U; Tinius, W; Gonschorek, S; vom Scheidt, J

1988-03-01

293

Novel absorption detection techniques for capillary electrophoresis  

SciTech Connect

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.

Xue, Y.

1994-07-27

294

Analysis of glycated hemoglobin A1c by capillary electrophoresis and capillary isoelectric focusing.  

PubMed

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

Koval, Dušan; Kaši?ka, Václav; Cottet, Hervé

2011-06-01

295

Mach-like capillary-gravity wakes  

NASA Astrophysics Data System (ADS)

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.

Moisy, Frédéric; Rabaud, Marc

2014-08-01

296

Mach-like capillary-gravity wakes.  

PubMed

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

Moisy, Frédéric; Rabaud, Marc

2014-08-01

297

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, ...

298

POLYSILOXANE DEACTIVATED FUSED SILICA CAPILLARIES CONTAINING IMMOBILIZED STATIONARY PHASES  

EPA Science Inventory

This article describes a method of preparing immobilized stationary phases which has arisen from the author's work on polysiloxane deactivation of fused silica capillaries. Although acid treatment is often omitted with fused silica capillaries, there are good reasons for hydrothe...

299

Research Article Mesenchymal cells stimulate capillary morphogenesis via distinct  

E-print Network

demonstrated that MSC-stimulated capillary formation relied solely on membrane-type matrix metalloproteinases: Capillary morphogenesis Angiogenesis Fibroblasts Mesenchymal stem cells Matrix metalloproteinases metalloproteinase; MSC, mesenchymal stem cell; MT-MMP, membrane-type matrix metalloproteinase; PA, plasminogen

George, Steven C.

300

Integrated Refractive Index Optical Ring Resonator Detector for Capillary Electrophoresis  

E-print Network

Integrated Refractive Index Optical Ring Resonator Detector for Capillary Electrophoresis Hongying Engineering, 240D Life Sciences Center, University of Missouri-Columbia, Columbia, Missouri 65211 a novel miniaturized and multiplexed, on- capillary, refractive index (RI) detector using liquid core

Fan, Xudong "Sherman"

301

Spatiotemporal instability of a confined capillary jet.  

PubMed

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

Herrada, M A; Gañán-Calvo, A M; Guillot, P

2008-10-01

302

Use of Plastic Capillaries for Macromolecular Crystallization  

NASA Technical Reports Server (NTRS)

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.

Potter, Rachel R.; Hong, Young-Soo; Ciszak, Ewa M.

2003-01-01

303

Observation of gravity-capillary wave turbulence.  

PubMed

We report the observation of the crossover between gravity and capillary wave turbulence on the surface of mercury. The probability density functions of the turbulent wave height are found to be asymmetric and thus non-Gaussian. The surface wave height displays power-law spectra in both regimes. In the capillary region, the exponent is in fair agreement with weak turbulence theory. In the gravity region, it depends on the forcing parameters. This can be related to the finite size of the container. In addition, the scaling of those spectra with the mean energy flux is found in disagreement with weak turbulence theory for both regimes. PMID:17359160

Falcon, Eric; Laroche, Claude; Fauve, Stéphan

2007-03-01

304

Skeletal muscle capillary density and fiber type are possible determinants of in vivo insulin resistance in man.  

PubMed Central

We have compared the capillary density and muscle fiber type of musculus vastus lateralis with in vivo insulin action determined by the euglycemic clamp (M value) in 23 Caucasians and 41 Pima Indian nondiabetic men. M value was significantly correlated with capillary density (r = 0.63; P less than or equal to 0.0001), percent type I fibers (r = 0.29; P less than 0.02), and percent type 2B fibers (r = -0.38; P less than 0.003). Fasting plasma glucose and insulin concentrations were significantly negatively correlated with capillary density (r = -0.46, P less than or equal to 0.0001; r = -0.47, P less than or equal to 0.0001, respectively). Waist circumference/thigh circumference ratio was correlated with percent type 1 fibers (r = -0.39; P less than 0.002). These results suggest that diffusion distance from capillary to muscle cells or some associated biochemical change, and fiber type, could play a role in determining in vivo insulin action. The association of muscle fiber type with body fat distribution may indicate that central obesity is only one aspect of a more generalized metabolic syndrome. The data may provide at least a partial explanation for the insulin resistance associated with obesity and for the altered kinetics of insulin action in the obese. PMID:3301899

Lillioja, S; Young, A A; Culter, C L; Ivy, J L; Abbott, W G; Zawadzki, J K; Yki-Järvinen, H; Christin, L; Secomb, T W; Bogardus, C

1987-01-01

305

Upscaling Capillary Pressure-Saturation Curves in Heterogeneous Porous Media  

Microsoft Academic Search

Numerical models of flow in the vadose zone require capillary pressure-saturation relationships for the grid blocks discretizing the medium. However, the scale of these grid blocks is generally much larger than the sample scale at which capillary pressure-saturation relationships are measured. This study investigates the upscaling of capillary curves under static conditions of capillary-gravity equilibrium. The averaging regions are horizontal

A. J. Desbarats

1995-01-01

306

Spectrometer capillary vessel and method of making same  

DOEpatents

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.

Linehan, John C. (Richland, WA); Yonker, Clement R. (Kennewick, WA); Zemanian, Thomas S. (Richland, WA); Franz, James A. (Kennewick, WA)

1995-01-01

307

Spectrometer capillary vessel and method of making same  

DOEpatents

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.

Linehan, J.C.; Yonker, C.R.; Zemanian, T.S.; Franz, J.A.

1995-11-21

308

Improved column preparation and performance in capillary electrochromatography  

Microsoft Academic Search

Problems encountered in capillary electrochromatography, i.e. non-reproducible column manufacture, bubble formation during usage, short column lifetimes and limited choice of packing particles are addressed by the development of fritless or single-frit, internally tapered, segmented and dead-volume free coupled capillary columns. The Van Deemter plots measured demonstrate the performance of these high-quality capillaries which are suitable for capillary electrochromatography as well

Erdmann Rapp; Ernst Bayer

2000-01-01

309

Investigation into the photo-induced change in wettability of hydrophobized TiO 2 films  

NASA Astrophysics Data System (ADS)

The photo-induced change in wettability of hydrophobized TiO 2 films has been investigated for steel coated with acidic TiO 2 nanosols containing varying concentrations of dispersed nanocrystalline titania, such as Degussa P25. The photo-induced change in wettability was evaluated by measuring the time-dependent drop of water contact angle (WCA) after samples had been soaked in either n-octyltriethoxysilane (OTS) or decanoic acid (DA). TiO 2 films treated in this way exhibit superhydrophobic behaviour, with WCA greater than 160°. After radiation with UV (black light), the superhydrophobic properties are transformed into superhydrophilic properties, with WCA of almost 0°. As P25 content and layer thickness increase, high rates of photo-induced change are found, but a moderate calcination regime is required. On the other hand, hardness and E modulus pass through a maximum at 25 wt% P25, so that a P25 content between 25 and 50 wt% is the optimum for practical uses. With such stable coatings, wettability can be controlled over a wide range, and the switch between hydrophobic and hydrophilic states can be carried out repeatedly when DA is used as the hydrophobizing agent. Use of a low calcination temperature (450 °C) for the intermediate annealing of the single layers in multilayer coatings and a short final sintering step at a relatively high temperature (e.g. 630 °C for 10 min) allow the preparation of relatively thin TiO 2 films on steel with a high photoactivity.

Risse, Gunter; Matys, Sabine; Böttcher, Horst

2008-07-01

310

Wettability alteration upon reaction with scCO2: Silica, mica, and calcite  

NASA Astrophysics Data System (ADS)

When brine and supercritical CO2 (scCO2) contact with a substrate (mineral surface), the equilibrium configuration among the three interfacial tensions determines the wetting property (measured by contact angles) of the substrate. Wettability is one of the most important reservoir properties in geological carbon sequestration, which largely impacts mobility of the injected CO2, and CO2 storage capacity of the reservoir. Although CO2 is commonly assumed to be the non-wetting phase in the current predictive models for CO2 storage capacity, a few recent studies have begun to show that the wettability of caprock minerals can be altered in the presence of scCO2 under pressures and temperatures representative of geological storage conditions. However results from these studies are not consistent and few data are available. In this paper we report our studies on wettability alteration of three minerals: silica, mica, and calcite, with contact angle measurements at varied pressures (7 to 25 MPa) and at temperature 45C, under different ionic strengths (1.0 to 5.0 M NaCl) of the brine phase. We will also report the effects of roughness of the mineral surfaces, and droplet sizes of the fluid phases on contact angle values. The results show that the contact angles largely increased in the presence of scCO2 with increased pressure and ion-strength for mica and silica. In contrast, only small changes in contact angles were obtained in measurements on calcite. The mechanisms responsible for these changes, and influences of the different substrates will be discussed.

Jung, J.; Wan, J.

2011-12-01

311

Incorporation of polymerizable surfactants in hydroxyethyl methacrylate lenses for improving wettability and lubricity.  

PubMed

Dryness and discomfort are the main reasons for dropouts in contact lens wearers. Incorporating surfactants in lens formulations could improve wettability and lubricity, which can improve comfort. We have focused on incorporating polymerizable surfactants in hydroxyethyl methacrylate lenses to improve comfort, while minimizing the potential for surfactant release into the tears. The surfactants were added to the polymerization mixture, followed by UV curing and extraction of leachables in hot water. Wettability and lubricity were characterized by measuring the contact angle and coefficient of friction. Lenses were also characterized by measuring transmittance, loss and storage moduli and ion permeability. Incorporation of surfactants significantly reduced contact angle from 90° for p-HEMA gels to about 10° for 2.43% (w/w) surfactant loading in hydrated gel. The coefficient of friction also decreased from about 0.16 for HEMA gels to 0.05 for the gels with 2.43% surfactant loading. There was a good correlation between the contact angle and coefficient of friction suggesting that both effects can be related to the stretching of the surfactant tails near the surface into the aqueous phase. The water content was also correlated with the surfactant loading but the contact angle was more sensitive suggesting that the observed improvements in wettability and lubricity arise from the protrusion of the surfactant tails in into the liquid, and not purely from the increase in the water content. The gels were clear and certain compositions also have the capability to block UVC and UVB radiation. The results suggest that incorporation of polymerizable surfactants could be useful in improving surface properties without significantly impacting any bulk property. PMID:25596369

Bengani, Lokendrakumar C; Scheiffele, Gary W; Chauhan, Anuj

2015-05-01

312

Enhancement of Surface Wettability via the Modification of Microtextured Titanium Implant Surfaces with Polyelectrolytes  

PubMed Central

Micrometer- and submicrometer-scale surface roughness enhances osteoblast differentiation on titanium (Ti) substrates and increases bone-to-implant contact in vivo. However, the low surface wettability induced by surface roughness can retard initial interactions with the physiological environment. We examined chemical modifications of Ti surfaces [pretreated (PT), Ra ? 0.3 ?m; sand blasted/acid etched (SLA), Ra ? 3.0 ?m] in order to modify surface hydrophilicity. We designed coating layers of polyelectrolytes that did not alter the surface microstructure but increased surface ionic character, including chitosan (CHI), poly(l-glutamic acid) (PGA), and poly(l-lysine) (PLL). Ti disks were cleaned and sterilized. Surface chemical composition, roughness, wettability, and morphology of surfaces before and after polyelectrolyte coating were examined by X-ray photoelectron spectroscopy (XPS), contact mode profilometry, contact angle measurement, and scanning electron microscopy (SEM). High-resolution XPS spectra data validated the formation of polyelectrolyte layers on top of the Ti surface. The surface coverage of the polyelectrolyte adsorbed on Ti surfaces was evaluated with the pertinent SEM images and XPS peak intensity as a function of polyelectrolyte adsorption time on the Ti surface. PLL was coated in a uniform thin layer on the PT surface. CHI and PGA were coated evenly on PT, albeit in an incomplete monolayer. CHI, PGA, and PLL were coated on the SLA surface with complete coverage. The selected polyelectrolytes enhanced surface wettability without modifying surface roughness. These chemically modified surfaces on implant devices can contribute to the enhancement of osteoblast differentiation. PMID:21513319

Park, Jung Hwa; Schwartz, Zvi; Olivares-Navarrete, Rene; Boyan, Barbara D.; Tannenbaum, Rina

2014-01-01

313

?-cyclodextrin and its hyperbranched polymers-induced micro/nanopatterns and tunable wettability on polymer surfaces  

NASA Astrophysics Data System (ADS)

This paper reports an efficient strategy to fabricate micro/nanopatterns on the surfaces of polymers for obtaining tunable wettability. Tepee-like bundles as micro/nanopatterns, composed of irregular polygon ``podium'' and ``valley'' structures, are formed by adding ?-cyclodextrin (?-CD) or its hyperbranched polymers [HBP(?-CD)s] into a polystyrene (PS) matrix in the process of anodized aluminum oxide (AAO) template wetting. The degree and region of micro/nanopatterns are evidently enlarged with the increase of ?-CD content or the molecular weight (Mw) of HBP(?-CD). The formation of micro/nanopatterns is mainly dependant on the self-organization of long and flexible aligned nanofiber/nanotube arrays with high aspect ratios, which are generated by the enhanced nanoflow behaviors of ?-CD or HBP(?-CD)-containing PS melts in AAO templates. The final topographies of micro/nanopatterns are determined by the dilation stress and the interactions of nanofibers/nanotubes during the template's removal and solvent evaporation process. The static and dynamic water contact angle measurements show that the wettability of micro/nanopatterned surfaces is systematically tuned from being merely hydrophobic to being highly hydrophobic, and to being finally superhydrophobic by simply adjusting the content of ?-CD or the Mw of HBP(?-CD) due to the decrease of the contact area fraction of the water droplet and solid polymer. The reported novel method, using nanoparticles or hyperbranched polymers as processing aids to induce micro/nanopatterns and tunable wettability on polymer surfaces, may be extended to various polymeric matrices to realize nanopatterns, and is useful for tailoring artificial superhydrophobic surfaces as well.

Tian, Wei; Xu, Yan; Huang, Longbiao; Yung, Kai-Leung; Xie, Yunchuan; Chen, Wei

2011-12-01

314

Photo-induced wettability of TiO{sub 2} film with Au buffer layer  

SciTech Connect

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.

Purkayastha, Debarun Dhar; Sangani, L. D. Varma; Krishna, M. Ghanashyam [School of Physics, University of Hyderabad, Hyderabad-500046 (India); Madhurima, V., E-mail: madhurima.v@gmail.com [Department of Physics, Central University of Tamil Nadu, Thiruvarur-610004 (India)

2014-04-24

315

Selective catalytic production of 5-hydroxymethylfurfural from glucose by adjusting catalyst wettability.  

PubMed

The development of highly-efficient catalysts for conversion of glucose and fructose to 5-hydroxymethylfurfural (HMF) is of great importance. In this work, theoretical simulations form the basis for rational design and synthesis of a superhydrophobic mesoporous acid, that can completely prevent HMF hydration, giving HMF as sole product from full conversion of fructose. Interestingly, the combined superhydrophobic solid acid and superhydrophilic solid base catalysts are very efficient for one-pot conversion of glucose to HMF, giving a yield as high as 95.4 %. The excellent catalytic data in the conversion of glucose to HMF is attributed to the unique wettabilities of the solid acid and base catalysts. PMID:24399510

Wang, Liang; Wang, Hong; Liu, Fujian; Zheng, Anmin; Zhang, Jian; Sun, Qi; Lewis, James P; Zhu, Longfeng; Meng, Xiangju; Xiao, Feng-Shou

2014-02-01

316

Wettability of a glass surface in the presence of two nonionic surfactant mixtures.  

PubMed

Measurements of the advancing contact angle (theta) were carried out for aqueous solution of p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycol), Triton X-100 (TX100), and Triton X-165 (TX165) mixtures on glass. The obtained results indicate that the wettability of glass depends on the concentration and composition of the surfactant mixture. The relationship between the contact angle and concentration suggests that the lowest wettability corresponds to the concentration of TX100 and TX165 and their mixture near the critical micelle concentration (CMC). The minimum of the dependence between the contact angle and composition of the mixtures for each concentration at a monomer mole fraction of TX100, alpha, equals 0.2 and 0.4 points to synergism in the wettability of the glass surface. In contrast to the results of Zisman ( Zisman, W. A. In Contact Angle, Wettability and Adhesion; Gould, R. F., Ed.; Advances in Chemistry Series 43; American Chemical Society Washington, DC, 1964; p 1 ) there was no linear dependence between cos theta and the surface tension of aqueous solutions of TX100 and TX165 mixtures for all studied systems, but a linear dependence exists between the adhesional tension and surface tension for glass, practically, in the whole concentration range of surfactants studied, the slopes of which are positive in the range of 0.43-0.67. These positive slopes indicate that the interactions between the water molecules and glass surface might be stronger than those between the surface and surfactant molecules. So, the surface excess of surfactant concentration at the glass-water interface is probably negative, and the possibility for surfactant to adsorb at the glass/water film-water interface is higher than that at the glass-water interface. This conclusion is confirmed by the values of the work of adhesion of "pure" surfactants, aqueous solutions of surfactants, and aqueous solutions of their mixtures to the glass surface and by the negative values of glass-water interfacial tension determined from the Young equation in the range of surfactant concentrations corresponding to their unsaturated monolayer at the water-air interface. PMID:18572957

Szymczyk, Katarzyna; Ja?czuk, Bronis?aw

2008-08-01

317

Reversible wettability of electron-beam deposited indium-tin-oxide driven by ns-UV irradiation  

SciTech Connect

Indium tin oxide (ITO) is one of the most widely used semiconductor oxides in the field of organic optoelectronics, especially for the realization of anode contacts. Here the authors report on the control of the wettability properties of ITO films deposited by reactive electron beam deposition and irradiated by means of nanosecond-pulsed UV irradiation. The enhancement of the surface water wettability, with a reduction of the water contact angle larger than 50 deg., is achieved by few tens of seconds of irradiation. The analyzed photo-induced wettability change is fully reversible in agreement with a surface-defect model, and it can be exploited to realize optically transparent, conductive surfaces with controllable wetting properties for sensors and microfluidic circuits.

Persano, Luana [NNL, National Nanotechnology Laboratory of CNR-Istituto Nanoscienze, Universita del Salento, via Arnesano, I-73100 Lecce (Italy); Center for Biomolecular Nanotechnologies UNILE, Istituto Italiano di Tecnologia, Via Barsanti, I-73010 Arnesano-LE (Italy); Del Carro, Pompilio [NNL, National Nanotechnology Laboratory of CNR-Istituto Nanoscienze, Universita del Salento, via Arnesano, I-73100 Lecce (Italy); Pisignano, Dario [NNL, National Nanotechnology Laboratory of CNR-Istituto Nanoscienze, Universita del Salento, via Arnesano, I-73100 Lecce (Italy); Center for Biomolecular Nanotechnologies UNILE, Istituto Italiano di Tecnologia, Via Barsanti, I-73010 Arnesano-LE (Italy); Dipartimento di Matematica e Fisica ''Ennio De Giorgi'', Universita del Salento, via Arnesano, I-73100 Lecce (Italy)

2012-04-09

318

Experimental analysis of refrigerant mixtures flow through adiabatic capillary tubes  

Microsoft Academic Search

This paper presents an experimental study on HCFC 22 alternative refrigerant mixtures flow through capillary tubes. Results for R-410A and R-407C show that the main operational parameters affect in a similar way the performance of capillary tubes for both refrigerants. The influence of geometry on the bahaviour of capillary tubes in refrigeration systems is characterised. An analysis on the differences

Flávio Augusto Sanzovo Fiorelli; Alex Alberto Silva Huerta; Otávio de Mattos Silvares

2002-01-01

319

SEPARATION OF GLUTEN PROTEINS BY HIGH PERFORMANCE CAPILLARY ELECTROPHORESIS  

Technology Transfer Automated Retrieval System (TEKTRAN)

High performance capillary electrophoresis (HPCE) is an analytical method that uses a voltage differential to accurately move solvents and solutes through a capillary. HPCE is a relative newcomer to the field of cereal chemistry, it utilizes small inner diameter capillaries as an anti-convective med...

320

Development of capillary optics for microbeam applications with synchrotron radition  

Microsoft Academic Search

Capillary optics have been suggested some time ago to confine x-ray beams to the size of a few microns. First experiments using glass capillaries of various sizes and shapes have been reported recently. We discuss the design and fabrication of capillary optics at CHESS, the Cornell High Energy Synchrotron Source, for applications such as Laue diffraction, x-ray fluorescence, and small

Reinhard Pahl; Donald H. Bilderback

1996-01-01

321

Laser illumination of multiple capillaries that form a waveguide  

DOEpatents

A system and method are disclosed for efficient laser illumination of the interiors of multiple capillaries simultaneously, and collection of light emitted from them. Capillaries in a parallel array can form an optical waveguide wherein refraction at the cylindrical surfaces confines side-on illuminating light to the core of each successive capillary in the array. Methods are provided for determining conditions where capillaries will form a waveguide and for assessing and minimizing losses due to reflection. Light can be delivered to the arrayed capillaries through an integrated fiber optic transmitter or through a pair of such transmitters aligned coaxially at opposite sides of the array. Light emitted from materials within the capillaries can be carried to a detection system through optical fibers, each of which collects light from a single capillary, with little cross talk between the capillaries. The collection ends of the optical fibers can be in a parallel array with the same spacing as the capillary array, so that the collection fibers can all be aligned to the capillaries simultaneously. Applicability includes improving the efficiency of many analytical methods that use capillaries, including particularly high-throughput DNA sequencing and diagnostic methods based on capillary electrophoresis. 35 figs.

Dhadwal, H.S.; Quesada, M.A.; Studier, F.W.

1998-08-04

322

Laser illumination of multiple capillaries that form a waveguide  

DOEpatents

A system and method are disclosed for efficient laser illumination of the interiors of multiple capillaries simultaneously, and collection of light emitted from them. Capillaries in a parallel array can form an optical waveguide wherein refraction at the cylindrical surfaces confines side-on illuminating light to the core of each successive capillary in the array. Methods are provided for determining conditions where capillaries will form a waveguide and for assessing and minimizing losses due to reflection. Light can be delivered to the arrayed capillaries through an integrated fiber optic transmitter or through a pair of such transmitters aligned coaxially at opposite sides of the array. Light emitted from materials within the capillaries can be carried to a detection system through optical fibers, each of which collects light from a single capillary, with little cross talk between the capillaries. The collection ends of the optical fibers can be in a parallel array with the same spacing as the capillary array, so that the collection fibers can all be aligned to the capillaries simultaneously. Applicability includes improving the efficiency of many analytical methods that use capillaries, including particularly high-throughput DNA sequencing and diagnostic methods based on capillary electrophoresis.

Dhadwal, Harbans S. (Setauket, NY); Quesada, Mark A. (Middle Island, NY); Studier, F. William (Stony Brook, NY)

1998-08-04

323

Effects of Er: YAG laser irradiation on wettability, surface roughness, and biocompatibility of SLA titanium surfaces: an in vitro study.  

PubMed

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 100 mJ, with a pulse frequency of 10 Hz under water irrigation for 1 min. 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

Ayobian-Markazi, Nader; Karimi, Mohammadreza; Safar-Hajhosseini, Ali

2013-06-13

324

Integrated, Multi-Scale Characterization of Imbibition and Wettability Phenomena Using Magnetic Resonance and Wide-Band Dielectric Measurements  

SciTech Connect

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.

Mukul M. Sharma; Steven L. Bryant; Carlos Torres-Verdin; George Hirasaki

2007-09-30

325

Analytical biotechnology: Capillary electrophoresis and chromatography  

SciTech Connect

The papers describe the separation, characterization, and equipment required for the electrophoresis or chromatography of cyclic nucleotides, pharmaceuticals, therapeutic proteins, recombinant DNA products, pheromones, peptides, and other biological materials. One paper, On-column radioisotope detection for capillary electrophoresis, has been indexed separately for inclusion on the data base.

Horvath, C.; Nikelly, J.G. (eds.)

1990-01-01

326

Illposedness of the gravity-capillary equations  

E-print Network

We prove via explicitly constructed initial data that solutions to the gravity-capillary wave system in $\\mathbb{R}^3$ representing a 2d air-water interface immediately fails to be $C^3$ with respect to the initial data if the initial data $(h_0, \\psi_0) \\in H^{s+\\frac12} \\otimes H^{s}$ for $swater wave system.

Chen, Robin Ming; Spirn, Daniel; Wright, J Douglas

2011-01-01

327

Micromolding in capillaries: Applications in materials science  

Microsoft Academic Search

Procedures based on micromolding in capillaries (MIMIC) were used to pattern a surface of a substrate with micrometer- and submicrometer-scale structures. An elastomer stamp made of poly(dimethylsiloxane) and having relief features in its surface was placed on a substrate; contact between the elastomeric stamp and the substrate formed a network of interconnected channels. A fluid - a precursor to a

Enoch Kim; Younan Xia; George M. Whitesides

1996-01-01

328

Sliding discharge in capillary for honeycomb catalyst  

Microsoft Academic Search

Condition of sliding discharge has been investigated to ionize inside honeycomb catalysts for exhaust gas cleaning. In order to improve selectivity and energy efficiency to promote plasma chemical reactions, combination of plasma and catalyst is effective. Packed bed is connected to capillary tubes. Ac discharge is formed in the packed bed, and with the dc electric field ionization can be

Satoshi Sato; Hiroki Yamauchi; Kazunori Takashima; Akira Mizuno

329

Derive capillary pressure from well logs  

SciTech Connect

A new approach has been developed to estimate in-situ capillary pressure and relative permeability characteristics in the transition zone. The technique is based on incorporating petrophysical data measured on core samples with well log analysis. Relative permeability can be determined for both drainage and inhibition conditions using the matched capillary pressure data. A technique has been developed to extrapolate petro-physical data where core data is absent or not representative of in-situ conditions. It is based on using log data to derive a water saturation vs. depth profile in the transition zone of the formation of interest. The log-derived water saturation distribution is then correlated to generalized capillary pressure curves typical of the formation studied. The capillary pressure type curves are generated from available core data and other petrophysical information. Relative permeability curves are then generated using correlations based on Purcell's model. The technique can be used in multi-layered and homogeneous reservoirs provided that one homogeneous layer is at least 20 ft thick.

Ibrahim, A. (Suez Canal Univ. (Egypt)); Desbrandes, R.; Bassiouni, Z. (Louisiana State Univ., Baton Rouge, LA (United States))

1994-07-01

330

Recent enhancements to capillary pumped loop systems  

Microsoft Academic Search

Design modifications to the evaporator pump and condenser section of an ammonia capillary pumped loop (CPL) system were tested to assess their effects on CPL performance. Vaporization enhancement grooves (VEGs) machined into the lands of the evaporator pump extrusion succeeded in increasing the heat transfer coefficient between the evaporator pump wall and CPL vapor by a factor of two. A

John Pohner; David Antoniuk

1991-01-01

331

Electromagnetically-driven capillary switches and oscillators  

Microsoft Academic Search

By designing pinned-contact, coupled droplet pairs at the appropriate length scale to promote surface tension as the dominant force, one can create bi-stable capillary switches and natural oscillators. These systems have been triggered by pressure pulses, electrochemistry, and electroosmosis. These methods are typically accompanied by bulky setups or slow response times. An alternate approach exploits electromagnetic activation. Our device consists

Bernard Malouin; Amir Hirsa; Michael Vogel

2009-01-01

332

Photodynamic Therapy for Juxtapapillary Retinal Capillary Hemangioma  

PubMed Central

Various treatment modalities have been described for retinal capillary hemangioma. Our purpose is to present a case of juxtapapillary retinal capillary hemangioma treated with photodynamic therapy. A 69-year-old woman with no previous ocular history presented with blurred vision and photopsias in the right eye three months ago. At presentation, her best corrected visual acuity was 6/9 in the right eye and 6/6 in the left eye. The anterior segment was totally normal and IOP was normal in both eyes as well. Dilated fundoscopy revealed a yellowish, well-circumscribed, elevated area with blood vessels, on the inferior margin of the right optic disc, as optic disc edema. Fluorescein angiography and angiogram with indocyanine green confirmed the diagnosis of juxtapapillary retinal capillary hemangioma. The patient was treated with photodynamic therapy with verteporfin and three months later her visual acuity was 6/7.5 in the right eye, while the lesion was slightly smaller. These findings remained stable at the one-year follow-up. In conclusion, photodynamic therapy offers promising anatomical and functional results for juxtapapillary retinal capillary hemangioma, providing visual acuity improvement or even stabilization and restriction of enlargement of the lesion. PMID:24716060

Mitropoulos, Panagiotis G.; Chatziralli, Irini P.; Peponis, Vasileios G.; Tsiotra, Vasileia A.; Parikakis, Efstratios A.

2014-01-01

333

DNA ADDUCT RESEARCH WITH CAPILLARY ELECTROPHORESIS  

EPA Science Inventory

DNA's central importance in all biological systems dictates a wide variety of DNA-related research. or much of this research, the utilization of capillary electrophoresis (CE) can be of significant advantage. pen-tube CE yields excellent separations of DNA components, which can b...

334

Protein Charge Ladders, Capillary Electrophoresis, and  

E-print Network

Protein Charge Ladders, Capillary Electrophoresis, and the Role of Electrostatics in Biomolecular Introduction Life rests on a web of molecular recognition;1,2 the folding of proteins, the hybridization the recognition site of the protein. Hydrophobic interactions, although still a challenge to describe

Prentiss, Mara

335

A novel capillary polymerase chain reaction machine  

E-print Network

I built a novel prototype capillary polymerase chain reaction machine. The purpose was to perform a single reaction as fast as possible with a reaction volume - 100 nl. The PCR mix is in the form of a 1 /1 droplet that ...

Chiou, Jeffrey Tsungshuan

2001-01-01

336

Planetary In Situ Capillary Electrophoresis System (PISCES)  

NASA Astrophysics Data System (ADS)

We propose to develop PISCES, a 3-kg, 2W, flight-capable microfluidic lab-on-a-chip capillary electrophoresis analyzer capable of ingesting solid, liquid, or gas samples and performing a suite of chemical analyses with parts per trillion sensitivity.

Willis, P. A.; Stockton, A. M.; Mora, M. F.; Cable, M. L.; Bramall, N. E.; Jensen, E. C.; Jiao, H.; Lynch, E.; Mathies, R. A.

2012-10-01

337

Dynamics of a capillary invasion in a closed-end capillary.  

PubMed

The position of fluid invasion in an open capillary increases as the square root of time and ceases when the capillary and hydrostatic forces are balanced, when viscous and inertia terms are negligible. Although this fluid invasion into open-end capillaries has been well described, detailed studies of fluid invasion in closed-end capillaries have not been explored thoroughly. Thus, we demonstrated, both theoretically and experimentally, a fluid invasion in closed-end capillaries, where the movement of the meniscus and the invasion velocity are accompanied by adiabatic gas compression inside the capillary. Theoretically, we found the fluid oscillations during invasion at short time scales by solving the one-dimensional momentum balance. This oscillatory motion is evaluated to determine which physical forces dominate the different conditions, and is further described by a damped driven harmonic oscillator model. However, this oscillating motion is not observed in the experiments. This inconsistency is due to the following: first, a continuous decrease in the radius of the curvature caused by decreasing the invasion velocity and increasing pressure inside the closed-end capillary, and second, the shear stress increase in the short time scale by the plug like velocity profile within the entrance length. The viscous term of modified momentum equation can be written as K(8?l/rc(2))(dl/dt) by using the multiplying factor K, which represents the increase of shear stress. The K is 7.3, 5.1, and 4.8 while capillary aspect ratio ?c is 740, 1008, and 1244, respectively. PMID:24984765

Lim, Hosub; Tripathi, Anubhav; Lee, Jinkee

2014-08-12

338

Modelling capillary oxygen supply capacity in mixed muscles: capillary domains revisited.  

PubMed

Developing effective therapeutic interventions for pathological conditions associated with abnormal oxygen transport to muscle fibres critically depends on the objective characterisation of capillarity. Local indices of capillary supply have the potential to identify the onset of fine-scale tissue pathologies and dysregulation. Detailed tissue geometry, such as muscle fibre size, has been incorporated into such measures by considering the distribution of Voronoi polygons (VP) generated from planar capillary locations as a representation of capillary supply regions. Previously, detailed simulations have predicted that this is generally accurate for muscle tissue with uniform oxygen uptake. Here we extend this modelling framework to heterogeneous muscle for the assessment of capillary supply capacity under maximal sustainable oxygen consumption. We demonstrate for muscle with heterogeneous fibre properties that VP theoretically provide a computationally simple but often accurate representation of trapping regions (TR), which are predicted from biophysical transport models to represent the areas of tissue supplied by individual capillaries. However, this use of VP may become less accurate around large fibres, and at the interface of fibres of largely different oxidative capacities. In such cases, TR may provide a more robust representation of capillary supply regions. Additionally, given VP can only approximate oxygen delivery by capillaries, we show that their generally close relationship to TR suggests that (1) fibre type distribution may be tightly regulated to avoid large fibres with high oxidative capacities, (2) the anatomical fibre distribution is also tightly regulated to prevent a large surface area of interaction between metabolically dissimilar fibres, and (3) in chronically hypoxic tissues capillary distribution is more important in determining oxygen supply than the spatial heterogeneity of fibre demand. PMID:24768706

Al-Shammari, Abdullah A; Gaffney, Eamonn A; Egginton, Stuart

2014-09-01

339

New concept for coal wettability evaluation and modulation. Technical progress report for the project, July 1, 1995--September 30, 1995  

SciTech Connect

This project is concerned with the new concept for coal surface wettability and floatability evaluation and modulation. the objective of the work is 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 application. In this quarter, the mini-cell flotation tests are conducted to study kinetic floatability and kinetic collectability of coal and pyrite. The kinetic floatability of the five samples have been tested with methanol, butanol, and hexanol as collector.

Hu, W.

1995-12-31

340

Nonlinear wave processes in porous waterlike media containing a system of capillaries partially filled with a viscous liquid  

NASA Astrophysics Data System (ADS)

A nonlinear dynamic state equation of waterlike porous material that contains a system of cylindrical capillaries partially filled with viscous liquid was received. It is shown that an acoustic nonlinearity of such media contains the relaxation elastic and inelastic components due to the nonlinear dependence of the capillary and viscous pressure in fluid on the capillary diameter. For the medium, theoretical study of such nonlinear phenomena as generation of the second harmonic and a difference frequency wave, self-demodulation of high-frequency pulses as well as the change in the propagation velocity and absorption coefficient of a test wave being under an action of static loading have been carried out. The frequency dependences of medium nonlinearity parameters for these processes were determined.

Nazarov, V. E.; Kiyashko, S. B.

2013-03-01

341

Neutrophil transit times through pulmonary capillaries: the effects of capillary geometry and fMLP-stimulation.  

PubMed Central

The deformations of neutrophils as they pass through the pulmonary microcirculation affect their transit time, their tendency to contact and interact with the endothelial surface, and potentially their degree of activation. Here we model the cell as a viscoelastic Maxwell material bounded by constant surface tension and simulate indentation experiments to quantify the effects of (N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP)-stimulation on its mechanical properties (elastic shear modulus and viscosity). We then simulate neutrophil transit through individual pulmonary capillary segments to determine the relative effects of capillary geometry and fMLP-stimulation on transit time. Indentation results indicate that neutrophil viscosity and shear modulus increase by factors of 3.4, for 10(-9) M fMLP, and 7.3, for 10(-6) M fMLP, over nonstimulated cell values, determined to be 30.8 Pa.s and 185 Pa, respectively. Capillary flow results indicate that capillary entrance radius of curvature has a significant effect on cell transit time, in addition to minimum capillary radius and neutrophil stimulation level. The relative effects of capillary geometry and fMLP on neutrophil transit time are presented as a simple dimensionless expression and their physiological significance is discussed. PMID:12324412

Bathe, Mark; Shirai, Atsushi; Doerschuk, Claire M; Kamm, Roger D

2002-01-01

342

Method of making tapered capillary tips with constant inner diameters  

DOEpatents

Methods of forming electrospray ionization emitter tips are disclosed herein. In one embodiment, an end portion of a capillary tube can be immersed into an etchant, wherein the etchant forms a concave meniscus on the outer surface of the capillary. Variable etching rates in the meniscus can cause an external taper to form. While etching the outer surface of the capillary wall, a fluid can be flowed through the interior of the capillary tube. Etching continues until the immersed portion of the capillary tube is completely etched away.

Kelly, Ryan T. (West Richland, WA); Page, Jason S. (Kennewick, WA); Tang, Keqi (Richland, WA); Smith, Richard D. (Richland, WA)

2009-02-17

343

Tolerance to systemic isotretinoin therapy in two patients using highly wettable contact lenses.  

PubMed

Purpose. Numerous ocular side effects have been reported with the use of systemic isotretinoin therapy. Herein, we presented two contact lens user patients who did not have contact lens intolerance during systemic isotretinoin therapy. Methods. 25-year-old male and 20-year-old female patients with severe acne vulgaris who were using highly wettable silicone hydrogel contact lenses which increase tear film stability were examined. Tear film function tests including Schirmer tests and tear break up time (TBUT) test and ocular surface staining with fluorescein were done. Subjective ocular complaints were scored with ocular surface disease index (OSDI) questionnaire. Patients were followed up monthly and examinations were repeated at each visit. Results. Both patients completed the therapy after a cumulative dose of 140?mg/kg isotretinoin in 6 months. The OSDI score and tear film function tests before and after treatment were all within normal limits. Discussion. Highly wettable contact lenses that provide increase in the tear film stability may be used during systemic retinoid therapy under close followups. Although isotretinoin affects ocular glands, the differences between tolerances to this retinoid therapy need to be investigated in larger patient groups using contact lenses. PMID:24707422

Arman, Ay?egül; Demirseren, D Deniz; Akoglu, Gulsen

2014-01-01

344

Tolerance to Systemic Isotretinoin Therapy in Two Patients Using Highly Wettable Contact Lenses  

PubMed Central

Purpose. Numerous ocular side effects have been reported with the use of systemic isotretinoin therapy. Herein, we presented two contact lens user patients who did not have contact lens intolerance during systemic isotretinoin therapy. Methods. 25-year-old male and 20-year-old female patients with severe acne vulgaris who were using highly wettable silicone hydrogel contact lenses which increase tear film stability were examined. Tear film function tests including Schirmer tests and tear break up time (TBUT) test and ocular surface staining with fluorescein were done. Subjective ocular complaints were scored with ocular surface disease index (OSDI) questionnaire. Patients were followed up monthly and examinations were repeated at each visit. Results. Both patients completed the therapy after a cumulative dose of 140?mg/kg isotretinoin in 6 months. The OSDI score and tear film function tests before and after treatment were all within normal limits. Discussion. Highly wettable contact lenses that provide increase in the tear film stability may be used during systemic retinoid therapy under close followups. Although isotretinoin affects ocular glands, the differences between tolerances to this retinoid therapy need to be investigated in larger patient groups using contact lenses. PMID:24707422

Arman, Ay?egül; Demirseren, D. Deniz

2014-01-01

345

Morphology and wettability of ZnO nanostructures prepared by hydrothermal method on various buffer layers  

NASA Astrophysics Data System (ADS)

Zinc oxide (ZnO) nanostructures were prepared by hydrothermal method on glass substrates with various buffer layers: Ag, Al, aluminum-doped zinc oxide (AZO) and tin-doped indium oxide (ITO). The structure, morphology and wettability of the ZnO nanostructured surfaces were investigated by using X-ray diffraction, scanning electron microscopy and water contact angle (WCA) analysis methods, respectively. All the nanostructures grown on glass with various buffer layers exhibited strong growth orientation along the (1 0 1) plane. The nature of the buffer layer was found to have remarkable effect on the morphology and wettability of the ZnO nanostructures. Whether the buffer layers were hydrophilic or low hydrophobic, all the ZnO nanostructures grown on the various buffer layers showed high hydrophobic property, and that grown on the AZO buffer layer even exhibited superhydrophobicity with a WCA of 151.1°. This work may provide a scientific basis for self-cleaning ZnO-based optoelectronic device applications.

Li, Bao-jia; Huang, Li-jing; Zhou, Ming; Ren, Nai-fei

2013-12-01

346

Wettability, polarity, and water absorption of holm oak leaves: effect of leaf side and age.  

PubMed

Plant trichomes play important protective functions and may have a major influence on leaf surface wettability. With the aim of gaining insight into trichome structure, composition, and function in relation to water-plant surface interactions, we analyzed the adaxial and abaxial leaf surface of holm oak (Quercus ilex) as a model. By measuring the leaf water potential 24 h after the deposition of water drops onto abaxial and adaxial surfaces, evidence for water penetration through the upper leaf side was gained in young and mature leaves. The structure and chemical composition of the abaxial (always present) and adaxial (occurring only in young leaves) trichomes were analyzed by various microscopic and analytical procedures. The adaxial surfaces were wettable and had a high degree of water drop adhesion in contrast to the highly unwettable and water-repellent abaxial holm oak leaf sides. The surface free energy and solubility parameter decreased with leaf age, with higher values determined for the adaxial sides. All holm oak leaf trichomes were covered with a cuticle. The abaxial trichomes were composed of 8% soluble waxes, 49% cutin, and 43% polysaccharides. For the adaxial side, it is concluded that trichomes and the scars after trichome shedding contribute to water uptake, while the abaxial leaf side is highly hydrophobic due to its high degree of pubescence and different trichome structure, composition, and density. Results are interpreted in terms of water-plant surface interactions, plant surface physical chemistry, and plant ecophysiology. PMID:24913938

Fernández, Victoria; Sancho-Knapik, Domingo; Guzmán, Paula; Peguero-Pina, José Javier; Gil, Luis; Karabourniotis, George; Khayet, Mohamed; Fasseas, Costas; Heredia-Guerrero, José Alejandro; Heredia, Antonio; Gil-Pelegrín, Eustaquio

2014-09-01

347

The effect of oxygen vacancies on water wettability of a ZnO surface.  

PubMed

In this study, the effect of oxygen vacancies on the water wettability of a hydrated ZnO(100) surface has been examined via molecular dynamics simulations with a reactive force field (ReaxFF). The results show that the oxygen vacancies on the ZnO surface change the structures of the ZnO surface and subsequently its water adsorption capability. While a 1 : 1 ratio of water to hydroxyl is observed for a water monolayer absorbed on ZnO(100) without oxygen vacancies, additional water adsorption as coordinate hydroxyl that resides on the vacancy site and bonds with three lattice zinc atoms is observed on the surfaces with oxygen vacancies. The results also show that the energy of the interaction per unit area between water and the hydrated ZnO surface is 55.1% higher in the presence of the oxygen vacancies than that without oxygen vacancies. This leads to a water contact angle of ~115° for the hydrated ZnO(100) surface in the absence of vacancies and ~21° with vacancies. The wetting kinetics of a water droplet on a ZnO(100) surface with and without oxygen vacancies are compared with the diffusion-limited reactive wetting and molecular kinetics models, respectively. In addition, the ordering of the vacancy sites is found not to significantly affect the wettability of the ZnO(100) surface. PMID:23949186

Hu, Han; Ji, Hai-Feng; Sun, Ying

2013-10-21

348

Biofilm formation on a TiO2 nanotube with controlled pore diameter and surface wettability.  

PubMed

Titania (TiO2) nanotube arrays (TNAs) with different pore diameters (140 - 20 nm) are fabricated via anodization using hydrofluoric acid (HF) containing ethylene glycol (EG) by changing the HF-to-EG volume ratio and the anodization voltage. To evaluate the effects of different pore diameters of TiO2 nanotubes on bacterial biofilm formation, Shewanella oneidensis (S. oneidensis) MR-1 cells and a crystal-violet biofilm assay are used. The surface roughness and wettability of the TNA surfaces as a function of pore diameter, measured via the contact angle and AFM techniques, are correlated with the controlled biofilm formation. Biofilm formation increases with the decreasing nanotube pore diameter, and a 20 nm TiO2 nanotube shows the maximum biofilm formation. The measurements revealed that 20 nm surfaces have the least hydrophilicity with the highest surface roughness of ?17 nm and that they show almost a 90% increase in the effective surface area relative to the 140 nm TNAs, which stimulate the cells more effectively to produce the pili to attach to the surface for more biofilm formation. The results demonstrate that bacterial cell adhesion (and hence, biofilm formation) can effectively be controlled by tuning the roughness and wettability of TNAs via controlling the pore diameters of TNA surfaces. This biofilm formation as a function of the surface properties of TNAs can be a potential candidate for both medical applications and as electrodes in microbial fuel cells. PMID:25604920

Anitha, V C; Lee, Jin-Hyung; Lee, Jintae; Narayan Banerjee, Arghya; Woo Joo, Sang; Ki Min, Bong

2015-02-13

349

Biofilm formation on a TiO2 nanotube with controlled pore diameter and surface wettability  

NASA Astrophysics Data System (ADS)

Titania (TiO2) nanotube arrays (TNAs) with different pore diameters (140 ? 20 nm) are fabricated via anodization using hydrofluoric acid (HF) containing ethylene glycol (EG) by changing the HF-to-EG volume ratio and the anodization voltage. To evaluate the effects of different pore diameters of TiO2 nanotubes on bacterial biofilm formation, Shewanella oneidensis (S. oneidensis) MR-1 cells and a crystal-violet biofilm assay are used. The surface roughness and wettability of the TNA surfaces as a function of pore diameter, measured via the contact angle and AFM techniques, are correlated with the controlled biofilm formation. Biofilm formation increases with the decreasing nanotube pore diameter, and a 20 nm TiO2 nanotube shows the maximum biofilm formation. The measurements revealed that 20 nm surfaces have the least hydrophilicity with the highest surface roughness of ?17 nm and that they show almost a 90% increase in the effective surface area relative to the 140 nm TNAs, which stimulate the cells more effectively to produce the pili to attach to the surface for more biofilm formation. The results demonstrate that bacterial cell adhesion (and hence, biofilm formation) can effectively be controlled by tuning the roughness and wettability of TNAs via controlling the pore diameters of TNA surfaces. This biofilm formation as a function of the surface properties of TNAs can be a potential candidate for both medical applications and as electrodes in microbial fuel cells.

Anitha, V. C.; Lee, Jin-Hyung; Lee, Jintae; Narayan Banerjee, Arghya; Joo, Sang Woo; Min, Bong Ki

2015-02-01

350

Electrochemical machining of super-hydrophobic Al surfaces and effect of processing parameters on wettability  

NASA Astrophysics Data System (ADS)

Super-hydrophobic aluminum (Al) surfaces were successfully fabricated via electrochemical machining in neutral NaClO3 electrolyte and subsequent fluoroalkylsilane (FAS) modification. The effects of the processing time, processing current density, and electrolyte concentration on the wettability, morphology, and roughness were studied. The surface morphology, chemical composition, and wettability of the Al surfaces were investigated using scanning electron microscopy (SEM) equipped with energy-dispersive spectroscopy (EDS), white-light interferometry, roughness measurements, X-ray diffraction (XRD), Fourier-transform infrared spectrometry (FTIR), and optical contact angle measurements. The results show that hierarchical rough structures and low surface energy films were present on the Al surfaces after electrochemical machining and FAS modification. The combination of the rough structures and the low surface energy materials plays a crucial role in achieving super-hydrophobicity. Compared with the anodic oxidation and chemical etching method, the method proposed in our work does not require strong acid or alkali, and causes less harm to the environment and operators but with high processing efficiency. The rough structures required by the super-hydrophobic surfaces were obtained at 30-s processing time and the best super-hydrophobicity with 164.6? water contact angle and 2? tilting angle was obtained at 360 s. The resulting super-hydrophobic Al surfaces have a long-time stability in air and an excellent resistance to corrosive liquids.

Song, Jin-long; Xu, Wen-ji; Liu, Xin; Lu, Yao; Sun, Jing

2012-09-01

351

Bioanalytical profile of the L-arginine/nitric oxide pathway and its evaluation by capillary electrophoresis?  

PubMed Central

This review briefly summarizes recent progress in fundamental understanding and analytical profiling of the L-arginine/nitric oxide (NO) pathway. It focuses on key analytical references of NO actions and on the experimental acquisition of these references in vivo, with capillary electrophoresis (CE) and high-performance capillary electrophoresis (HPCE) comprising one of the most flexible and technologically promising analytical platform for comprehensive high-resolution profiling of NO-related metabolites. Second aim of this review is to express demands and bridge efforts of experimental biologists, medical professionals and chemical analysis-oriented scientists who strive to understand evolution and physiological roles of NO and to develop analytical methods for use in biology and medicine. PMID:17329176

Boudko, Dmitri Y.

2007-01-01

352

Sterility Testing by Capillary Electrophoresis: A Comparison of On-line Preconcentration Approaches in Capillaries with Greater Internal Diameters  

PubMed Central

Detection of microbial contamination is of critical importance in the medical and the food industry. Rapid tests for the absence or presence of viable microorganisms are in urgent demand. Capillary electrophoresis is a modern analytical technique that can be adapted for rapid screening of microbial contamination. However, the small dimensions of capillaries allow introduction of only a small fraction of the sample, which can be problematic when examining large samples. In this article, we examine the possibilities of introducing larger sample volumes using capillaries with greater internal diameters (i.d.) together with different stacking techniques. The use of 0.32 mm i.d. capillary and the injection of 60 % of the capillary volume led to approximately 120-fold improvement of the injected sample volume over the classical injection 5% of a 0.10 mm i.d. capillary. The setup we described opens new possibilities in sterility testing using capillary electrophoresis. PMID:19847804

Petr, Jan; Jiang, Chunxia; Sevcik, Juraj; Tesarova, Eva; Armstrong, Daniel W.

2015-01-01

353

WATER RESOURCES RESEARCH, VOL. , NO. , PAGES 110, The Impact of Wettability Alteration on Two-Phase Flow  

E-print Network

WATER RESOURCES RESEARCH, VOL. , NO. , PAGES 1­10, The Impact of Wettability Alteration on Two (NAPLs) and gases that co-exist with water in soils and rocks, is of fundamental interest to subsurface water management. Any prediction of temporal and spatial distributions of these fluids is sensitive

Patzek, Tadeusz W.

354

Correlation between corrosion performance and surface wettability in ZrTiCuNiBe bulk metallic glasses  

E-print Network

Correlation between corrosion performance and surface wettability in ZrTiCuNiBe bulk metallic June 2010 The corrosion properties of two Zr-based bulk metallic glass, Zr41Ti14Cu12Ni10Be23 LM1 and Zr potential, LM1b showed superior corrosion resistance to LM1. Under identical sample preparation and testing

Zheng, Yufeng

355

Calcination-free micropatterning of rare-earth-ion-doped nanoparticle films on wettability-patterned surfaces of plastic sheets.  

PubMed

We demonstrate a patterning technique of rare-earth-ion-doped (RE) nanoparticle films directly on wettability-patterned surfaces fabricated on plastic sheets in one step. Self-assembled monolayers consisting of silane-coupling agent with hydrophobic groups were fabricated on plastic sheets. UV-ozone treatments were performed through a metal mask to selectively remove the self-assembled monolayers in a patterned manner, resulting in the formation of wettability-patterned surfaces on plastic sheets. Using a water dispersion of Er(3+) and Yb(3+)-codoped Y2O3 nanoparticles at a diameter of 100 nm, RE-nanoparticle films were fabricated on the wettability-patterned surfaces by a dip-coating technique. By adjusting the concentration of RE-nanoparticle dispersion, withdrawal speed, and withdrawal angle, amount of RE-nanoparticles, we were able to control the structures of the RE-nanoparticle films. Fluorescence microscope observations demonstrate that visible upconversion luminescence and near-infrared fluorescence were emitted from the RE-nanoparticle films on the wettability-patterned surfaces. This technique allows for the fabrication of flexible emitting devices with long-operating life time with minimized material consumption and few fabrication steps, and for the application to sensors, emitting devices, and displays in electronics, photonics, and bionics in the future. PMID:24655829

Watanabe, Satoshi; Hamada, Yudai; Hyodo, Hiroshi; Soga, Kohei; Matsumoto, Mutsuyoshi

2014-05-15

356

Capillary-Based Multi-Nanoelectrospray Emitters  

PubMed Central

We describe the coupling of liquid chromatography (LC) separations with mass spectrometry (MS) using nanoelectrospray ionization (nanoESI) multi-emitters. The array of 19 emitters reduced the flow rate delivered to each emitter, allowing the enhanced sensitivity that is characteristic of nanoESI to be extended to higher flow rate separations. The signal for peptides from spiked proteins in a human plasma tryptic digest increased 11-fold on average when the multi-emitters were employed, due to increased ionization efficiency and improved ion transfer efficiency through a newly designed heated multi-capillary MS inlet. Additionally, the LC peak signal-to-noise ratio increased ?7-fold when the multi-emitter configuration was used. The low dead volume of the emitter arrays preserved peak shape and resolution for robust capillary LC separations using total flow rates of 2-?L/min. PMID:18044958

Kelly, Ryan T.; Page, Jason S.; Zhao, Rui; Qian, Wei-Jun; Mottaz, Heather M.; Tang, Keqi; Smith, Richard D.

2008-01-01

357

Transversally periodic solitary gravity–capillary waves  

PubMed Central

When both gravity and surface tension effects are present, surface solitary water waves are known to exist in both two- and three-dimensional infinitely deep fluids. We describe here solutions bridging these two cases: travelling waves which are localized in the propagation direction and periodic in the transverse direction. These transversally periodic gravity–capillary solitary waves are found to be of either elevation or depression type, tend to plane waves below a critical transverse period and tend to solitary lumps as the transverse period tends to infinity. The waves are found numerically in a Hamiltonian system for water waves simplified by a cubic truncation of the Dirichlet-to-Neumann operator. This approximation has been proved to be very accurate for both two- and three-dimensional computations of fully localized gravity–capillary solitary waves. The stability properties of these waves are then investigated via the time evolution of perturbed wave profiles. PMID:24399922

Milewski, Paul A.; Wang, Zhan

2014-01-01

358

The geometry and wetting of capillary folding  

E-print Network

Capillary forces are involved in a variety of natural phenomena, ranging from droplet breakup to the physics of clouds. The forces from surface tension can also be exploited in industrial application provided the length scales involved are small enough. Recent experimental investigations showed how to take advantage of capillarity to fold planar structures into three-dimensional configurations by selectively melting polymeric hinges joining otherwise rigid shapes. In this paper we use theoretical calculations to quantify the role of geometry and fluid wetting on the final folded state. Considering folding in two and three dimensions, studying both hydrophilic and hydrophobic situations with possible contact angle hysteresis, and addressing the shapes to be folded to be successively infinite, finite, curved, kinked, elastic, we are able to derive an overview of the geometrical parameter space available for capillary folding.

Jean-Philippe Péraud; Eric Lauga

2014-03-18

359

Wetting kinetics in surface capillary grooves  

SciTech Connect

For V-shaped surface grooves in copper, we have obtained the capillary driven flow kinetics for two liquids: unreactive 1-heptanol and eutectic Sn/Pb solder, which is known to react with copper. We show experimentally that the flow of both liquids in these grooves follows the classical Washburn kinetics, i.e., a Poiseuille flow process, modified to include a dynamic contact angle. Because no subsidiary processes are necessary to fit our data, we propose that in this geometry capillary driven solder flow is too rapid for reaction to provide an appreciable effect. Thus, to observe the effects of Sn/Cu reaction kinetics, the flow rate must be decreased, which the present experiments allow through redesign of the groove geometry and size. 16 refs., 4 figs.

Rye, R.R.; Yost, F.G. [Sandia National Lab., Albuquerque, NM (United States)] [Sandia National Lab., Albuquerque, NM (United States); Mann, J.A. Jr. [Case Western Reserve Univ., Cleveland, OH (United States)] [Case Western Reserve Univ., Cleveland, OH (United States)

1996-10-02

360

Transversally periodic solitary gravity-capillary waves.  

PubMed

When both gravity and surface tension effects are present, surface solitary water waves are known to exist in both two- and three-dimensional infinitely deep fluids. We describe here solutions bridging these two cases: travelling waves which are localized in the propagation direction and periodic in the transverse direction. These transversally periodic gravity-capillary solitary waves are found to be of either elevation or depression type, tend to plane waves below a critical transverse period and tend to solitary lumps as the transverse period tends to infinity. The waves are found numerically in a Hamiltonian system for water waves simplified by a cubic truncation of the Dirichlet-to-Neumann operator. This approximation has been proved to be very accurate for both two- and three-dimensional computations of fully localized gravity-capillary solitary waves. The stability properties of these waves are then investigated via the time evolution of perturbed wave profiles. PMID:24399922

Milewski, Paul A; Wang, Zhan

2014-01-01

361

Capillary flow through heat-pipe wicks  

NASA Technical Reports Server (NTRS)

Theoretical expressions are obtained for the capillary-pressure limit and permeability of a fibrous wick in terms of the porosity and fiber diameter. Hysteresis in capillary pressure is included through the introduction of an empirical hysteresis constant. A partial-saturation model based on the statistical distribution of local porosity requires an additional empirical constant, the standard deviation. The theory is compared to results of a beta-ray absorption experiment that measured the liquid content of a partially saturated wick and to results of permeability measurements on partially and fully saturated wicks. A simple wick-weighing experiment is described that yields values for the empirical hysteresis constant and the standard deviation. Theoretical results are used to design an optimum wick.

Eninger, J. E.

1975-01-01

362

Finite-depth capillary-gravity dromions.  

PubMed

It is known that the governing equations for the evolution of the envelope of weakly nonlinear capillary-gravity wave packets, the so-called Davey-Stewartson equation, admit dromion solutions in the limit of shallow water and strong surface tension, i.e., when kh?1 and the Bond number (Bo) ?T/?gh^{2}>1/3 (where T is the surface tension coefficient and h the water depth). Here we show that capillary-gravity dromions exist beyond this limit for a broad range of finite water depths, i.e., for kh ? O(1), as well as for subcritical Bond numbers, i.e., for Bo < 1/3. PMID:24125393

Liang, Yong; Alam, Mohammad-Reza

2013-09-01

363

Capillary Study - Skylab Student Experiment ED-72  

NASA Technical Reports Server (NTRS)

This chart describes the Skylab student experiment ED-72, Capillary Study, proposed by Roger G. Johnson of St. Paul, Mirnesota. Johnson theorized that capillary rise might continue to infinity in Skylab's zero-gravity environment. The behavior of fluids, particularly their flow properties in a low-gravity environment, had been important from the time that Robert H. Goddard launched his liquid-fueled rockets in the 1920's to the more sophisticated space systems of the day. It was necessary to design fluid-flow systems that would not only overcome the lack of gravity but also overcome, or take advantage of, the effect of surface tension. In March 1972, NASA and the National Science Teachers Association selected 25 experiment proposals for flight on Skylab. Science advisors from the Marshall Space Flight Center aided and assisted the students in developing the proposals for flight on Skylab.

1973-01-01

364

Characterization and Alteration of Wettability States of Alaskan Reserviors to Improve Oil Recovery Efficiency (including the within-scope expansion based on Cyclic Water Injection - a pulsed waterflood for Enhanced Oil Recovery)  

SciTech Connect

Numerous early reports on experimental works relating to the role of wettability in various aspects of oil recovery have been published. Early examples of laboratory waterfloods show oil recovery increasing with increasing water-wetness. This result is consistent with the intuitive notion that strong wetting preference of the rock for water and associated strong capillary-imbibition forces gives the most efficient oil displacement. This report examines the effect of wettability on waterflooding and gasflooding processes respectively. Waterflood oil recoveries were examined for the dual cases of uniform and non-uniform wetting conditions. Based on the results of the literature review on effect of wettability and oil recovery, coreflooding experiments were designed to examine the effect of changing water chemistry (salinity) on residual oil saturation. Numerous corefloods were conducted on reservoir rock material from representative formations on the Alaska North Slope (ANS). The corefloods consisted of injecting water (reservoir water and ultra low-salinity ANS lake water) of different salinities in secondary as well as tertiary mode. Additionally, complete reservoir condition corefloods were also conducted using live oil. In all the tests, wettability indices, residual oil saturation, and oil recovery were measured. All results consistently lead to one conclusion; that is, a decrease in injection water salinity causes a reduction in residual oil saturation and a slight increase in water-wetness, both of which are comparable with literature observations. These observations have an intuitive appeal in that water easily imbibes into the core and displaces oil. Therefore, low-salinity waterfloods have the potential for improved oil recovery in the secondary recovery process, and ultra low-salinity ANS lake water is an attractive source of injection water or a source for diluting the high-salinity reservoir water. As part of the within-scope expansion of this project, cyclic water injection tests using high as well as low salinity were also conducted on several representative ANS core samples. These results indicate that less pore volume of water is required to recover the same amount of oil as compared with continuous water injection. Additionally, in cyclic water injection, oil is produced even during the idle time of water injection. It is understood that the injected brine front spreads/smears through the pores and displaces oil out uniformly rather than viscous fingering. The overall benefits of this project include increased oil production from existing Alaskan reservoirs. This conclusion is based on the performed experiments and results obtained on low-salinity water injection (including ANS lake water), vis-a-vis slightly altering the wetting conditions. Similarly, encouraging cyclic water-injection test results indicate that this method can help achieve residual oil saturation earlier than continuous water injection. If proved in field, this would be of great use, as more oil can be recovered through cyclic water injection for the same amount of water injected.

Abhijit Dandekar; Shirish Patil; Santanu Khataniar

2008-12-31

365

Capillary-Effect Root-Environment System  

NASA Technical Reports Server (NTRS)

Capillary-effect root-environment system (CERES) is experimental apparatus for growing plants in nutrient solutions. Solution circulated at slight tension in cavity filled with plastic screen and covered by porous plastic membrane. By adsorptive attraction, root draws solution through membrane. Conceived for use in microgravity of space, also finds terrestrial application in germinating seedlings, because it protects them from extremes of temperature, moisture, and soil pH and from overexposure to fertilizers and herbicides.

Wright, Bruce D.

1991-01-01

366

Capillary zone electrophoresis-mass spectrometer interface  

DOEpatents

A device for providing equal electrical potential between two loci unconnected by solid or liquid electrical conductors is provided. The device comprises a first electrical conducting terminal, a second electrical conducting terminal connected to the first terminal by a rigid dielectric structure, and an electrically conducting gas contacting the first and second terminals. This device is particularly suitable for application in the electrospray ionization interface between a capillary zone electrophoresis apparatus and a mass spectrometer. 1 fig.

D`Silva, A.

1996-08-06

367

Capillary zone electrophoresis-mass spectrometer interface  

DOEpatents

A device for providing equal electrical potential between two loci unconnected by solid or liquid electrical conducts is provided. The device comprises a first electrical conducting terminal, a second electrical conducting terminal connected to the first terminal by a rigid dielectric structure, and an electrically conducting gas contacting the first and second terminals. This device is particularly suitable for application in the electrospray ionization interface between a capillary zone electrophoresis apparatus and a mass spectrometer.

D'Silva, Arthur (Ames, IA)

1996-08-06

368

The Microcephaly-Capillary Malformation Syndrome  

PubMed Central

We report on three children from two families with a new pattern recognition malformation syndrome consisting of severe congenital microcephaly (MIC), intractable epilepsy including infantile spasms, and generalized capillary malformations that was first reported recently in this journal [Carter et al. (2011); Am J Med Genet A 155: 301–306]. Two of our reported patients are an affected brother and sister, suggesting this is an autosomal recessive severe congenital MIC syndrome. PMID:21815250

Mirzaa, Ghayda M.; Paciorkowski, Alex R.; Smyser, Christopher D.; Willing, Marcia C.; Lind, Anne C.; Dobyns, William B.

2012-01-01

369

The Roles of Titanium Surface Micro/Nanotopography and Wettability on the Differential Response of Human Osteoblast Lineage Cells  

PubMed Central

Surface micro and nanostructural modifications of dental and orthopaedic implants have shown promising in vitro, in vivo, and clinical results. Surface wettability has also been suggested to play an important role in osteoblast differentiation and osseointegration. However, the available techniques to measure surface wettability are not reliable on clinically-relevant, rough surfaces. Furthermore, how the differentiation state of osteoblast lineage cells impacts their response to micro/nanostructured surfaces, and the role of wettability on this response, remains unclear. In the current study, surface wettability analyses (optical sessile drop analysis, ESEM analysis, and the Wilhelmy technique) indicated hydrophobic static responses for deposited water droplets on microrough and micro/nanostructured specimens, while hydrophilic responses were observed with dynamic analyses of micro/nanostructured specimens. The maturation and local factor production of human immature osteoblast-like MG63 cells was synergistically influenced by nanostructures superimposed onto microrough titanium (Ti) surfaces. In contrast, human mesenchymal stem cells (MSCs) cultured on micro/nanostructured surfaces in the absence of exogenous soluble factors, exhibited less robust osteoblastic differentiation and local factor production compared to cultures on unmodified microroughened Ti. Our results support previous observations using Ti6Al4V surfaces showing that recognition of surface nanostructures and subsequent cell response is dependent on the differentiation state of osteoblast lineage cells. The results also indicate that this effect may be partly modulated by surface wettability. These findings support the conclusion that the successful osseointegration of an implant depends on contributions from osteoblast lineage cells at different stages of osteoblast commitment. PMID:23232211

Gittens, Rolando A.; Olivares-Navarrete, Rene; Cheng, Alice; Anderson, David M.; McLachlan, Taylor; Stephan, Ingrid; Geis-Gerstorfer, Jürgen; Sandhage, Kenneth H.; Fedorov, Andrei G.; Rupp, Frank; Boyan, Barbara D.; Tannenbaum, Rina; Schwartz, Zvi

2013-01-01

370

Capillary Morphogenesis in PEG-Collagen Hydrogels  

PubMed Central

A wide variety of hydrogels have been explored as 3D culture platforms and for applications in tissue engineering. Hydrogels formed from natural extracellular matrix (ECM) proteins readily support the formation of vasculature in vitro, but only a handful of hydrogels composed of synthetic materials have shown anything comparable. This relative lack of synthetic material options has hindered efforts to better understand how ECM cues direct vascularization. We developed a biosynthetic hydrogel consisting of polyethylene glycol diacrylamide conjugated to macromolecular type-I collagen. Through their acrylamide-based cross-links, these materials allow for independent control of physical properties and bulk ligand concentration. These hydrogels exhibited hydrolytic stability, but the collagen component retained its susceptibility to enzymatic remodeling. Photoencapsulation of endothelial cells and fibroblasts within this hydrogel material and their subsequent co-culture led to the formation of capillary vessel-like networks with well-defined hollow lumens. Capillary formation was prevented by inhibiting matrix metalloproteinase (MMP) activity, recapitulating the MMP-dependence of vascularization observed in natural hydrogels. These findings validate the utility of this material platform to decipher how the ECM regulates capillary morphogenesis and to support the formation of vascularized tissue constructs for potential applications in regenerative medicine. PMID:24021759

Singh, Rahul K.; Seliktar, Dror; Putnam, Andrew J.

2013-01-01

371

Fe³?-immobilized nanoparticle-modified capillary for capillary electrophoretic separation of phosphoproteins and non-phosphoproteins.  

PubMed

A fused-silica capillary modified with Fe³?-immobilized magnetic nanoparticles (Fe³?-IMAN) has been investigated for the capillary electrophoretic (CE) separation of phosphoproteins and non-phosphoproteins. The Fe³?-IMAN capillary was achieved by covalently immobilising epoxy-based magnetic silica nanoparticles (160?nm) on the prederivatized 3-aminopropyl-trimethoxysilane (APTMS) fused-silica capillary (75??m id), followed by disodium iminodiacetate and Fe³?. The buildup process was examined by measuring the streaming potentials of the bare capillary, APTMS capillary, epoxy-based nanoparticle capillary and Fe³?-IMAN capillary by varying the buffer pH. An inverted fluorescence microscope was used to determine the surface features of the Fe³?-IMAN capillary derivatized with morin. Further experimental results confirmed that Fe³?-IMAN bonded on the inner wall of the APTMS capillary could provide sufficient solute-bonded phase interactions to allow for the CE separation of phosphoproteins and non-phosphoproteins at concentration levels down to 50??g/mL. The highest number of theoretical plates obtained was about 233,000/m, and the relative standard deviation (RSD) for migration times was <2.57% for eight consecutive runs, respectively. Additionally, the Fe³?-IMAN modifing method was also applied to the analyses of bovine milk proteins. With simplicity, high resolving power, and high repeatability, the proposed method has shown great potential for phosphoproteomics applications. PMID:21953525

Hu, Qin; Hu, Shaoqiang; Zhang, Zhenyang; Zhou, Ximin; Yang, Shanshan; Zhang, Yuan; Chen, Xinguo

2011-10-01

372

Wettability behaviour of RTV silicone rubber coated on nanostructured aluminium surface  

NASA Astrophysics Data System (ADS)

A nanostructutered superhydrophobic surface was elaborated by applying an RTV silicone rubber coating on electrochemically processed aluminium substrates. Study of anodisation voltage on surface morphology showed that higher anodising voltage led to larger pore sizes. Scanning electron microscopy image analysis showed bird's nest and beehive structures formed on anodised surfaces at 50 V and 80 V. Water static contact angle on the treated surfaces reached up to 160° at room temperature. Study of superhydrophobic surfaces at super cooled temperature showed important delayed freezing time for RTV hydrophobic surfaces when compared to non-treated aluminium. However, lower wettability was observed when surface temperature went down from 20 °C to -10 °C. Also, it was found that the capacitance of superhydrophobic surfaces decreased with increasing anodising voltage.

Momen, Gelareh; Farzaneh, Masoud; Jafari, Reza

2011-05-01

373

On the effect of surface roughness height, wettability, and nanoporosity on Leidenfrost phenomena  

NASA Astrophysics Data System (ADS)

In recent quenching heat transfer studies of nanofluids, it was found that deposition of nanoparticles on a surface raises its Leidenfrost point (LFP) considerably [Kim et al., Int. J. Multiphase Flow 35, 427 (2009) and Kim et al., Int. J. Heat Mass Transfer 53, 1542 (2010)]. To probe the physical mechanism underlying this observation, the effects of surface properties on LFP of water droplets were studied, using custom-fabricated surfaces for which roughness height, wettability, and porosity were controlled at the nanoscale. This approach reveals that nanoporosity is the crucial feature in efficiently increasing the LFP by initiating heterogeneous nucleation of bubbles during short-lived solid-liquid contacts, which results in disruption of the vapor film.

Kim, Hyungdae; Truong, Bao; Buongiorno, Jacopo; Hu, Lin-Wen

2011-02-01

374

Merging of metal nanoparticles driven by selective wettability of silver nanostructures  

NASA Astrophysics Data System (ADS)

The welding and sintering of nanomaterials is relevant, for example, to form electrical contacts between metallic particles in printed electronic devices. Usually the welding of nanoparticles is achieved at high temperatures. Here we find that merging of two different metals, silver and gold nanoparticles, occurs on contact at room temperature. The merging process was investigated by experimental and molecular dynamics simulations. We discovered that the merging of these particles is driven by selective wettability of silver nanoparticles, independent of their size and shape (spheres or rods); silver behaves as a soft matter, whereas gold as a hard surface being wetted and retaining its original morphology. During that process, the silver atoms move towards the surface of the Au nanoparticles and wrap the Au nanoparticles in a pulling up-like process, leading to the wetting of Au nanoparticles.

Grouchko, Michael; Roitman, Polina; Zhu, Xi; Popov, Inna; Kamyshny, Alexander; Su, Haibin; Magdassi, Shlomo

2014-01-01

375

Importance of excipient wettability on tablet characteristics prepared by moisture activated dry granulation (MADG).  

PubMed

For moisture activated dry granulation (MADG), microcrystalline cellulose (MCC) or silicon dioxide is recommended for the moisture absorption stage. The aim of this study was to assess the suitability of alternative excipients as moisture absorbents with regard to the disintegration mechanism of resulting lactose based placebo formulations. Beside high and low moisture MCC grades, the additions of magnesium aluminometasilicate (MAMS), pregelatinized starch (S1500), crospovidone (Kollidon CL) and carmellose calcium (ECG 505) were evaluated. High shear granulation (HSG) was conducted as a reference process. The overall disintegration time of all tablets produced by MADG was significantly faster whereas hardness yield and mass-variability were equal or superior compared to the HSG process. Powder wettability of the different moisture absorbents was identified to be a key driver for rapid disintegration, whereas tablet porosity had only a minor influence on the target hardness of the tablets. PMID:23994013

Takasaki, Hiroshi; Yonemochi, Etsuo; Messerschmid, Roman; Ito, Masanori; Wada, Koichi; Terada, Katsuhide

2013-11-01

376

Tuning the wettability of an aluminum surface via a chemically deposited fractal dendrite structure.  

PubMed

We have developed a straightforward method to tune the wettability of an aluminum substrate within a contact angle (CA) range from 2(°) to 170(°) by chemical deposition in CuCl2 solution and fluoroalkylsilane (FAS) modification. The CA of the as-deposited surface decreases with deposition time due to the growth of fractal copper dendrites, which enhance the surface roughness significantly. After subsequent modification with FAS, a superhydrophobic surface with CA 170(°) and sliding angle less than 5(°) has been obtained. With the increase of CA, the maximum spreading of water droplets is reduced. A bouncing behavior is observed for droplets impinging on the superhydrophobic substrate, suggesting its potential application as a self-cleaning surface. PMID:23793831

Zang, Duyang; Li, Feng; Geng, Xingguo; Lin, Kejun; Clegg, Paul S

2013-06-01

377

Wettability, Oil Recovery, and Interfacial Tension with an SDBS-Dodecane-Kaolin System.  

PubMed

The wettability of kaolin with SDBS (sodium dodecyl benzene sulfonate) aqueous solutions was measured by the Washburn equation expressed as contact angles. The contact angle changes for SDBS aqueous solutions on kaolin surface was studied. The interfacial tension between the SDBS solutions and n-dodecane was measured using both drop volume and spinning drop methods. Then the oil recovery of n-dodecane on the kaolin surface was tested. It was found that the minimum contact angle (the most hydrophilic condition) and the maximum oil recovery occurred near the critical micelle concentration (CMC) of SDBS while the interfacial tension between the SDBS solution and n-dodecane was far from ultra-low. Copyright 1999 Academic Press. PMID:10339376

Bi; Zhang; Xu; Qian; Yu

1999-06-15

378

Growing hydrophobicity on a smooth copper oxide thin film at room temperature and reversible wettability transition  

NASA Astrophysics Data System (ADS)

The thin CuO film is acquired by a quick dip of copper in H2O2 solutions at room temperature. The CuO film appears smooth and exhibits superhydrophilic nature. The composition change cannot be verified by X-ray photoelectron spectroscopy but can be manifested by the water contact angle. In the ambient condition, the thickness of the oxidized layer and the surface hydrophobicity grow gradually, while the chemical composition of the overall oxidized film remains essentially unchanged. In the vacuum, the growth rate of the hydrophobicity is significantly elevated, revealing deoxidation on the upmost surface. Our results indicate that growing hydrophobicity on the CuO film is spontaneous and the reversible wettability transition can be observed by H2O2 oxidation and vacuum deoxidation.

Tu, Sheng-Hung; Wu, Hsing-Chen; Wu, Cyuan-Jhang; Cheng, Shao-Liang; Sheng, Yu-Jane; Tsao, Heng-Kwong

2014-10-01

379

Surface wettability of (3-aminopropyl)triethoxysilane self-assembled monolayers.  

PubMed

The (3-aminopropyl)triethoxysilane (APTES) self-assembled monolayer (SAM) has been widely used in fundamental research and engineering applications; however, characterization of its surface wetting properties remains problematic. Surface wetting properties of the APTES SAM were systematically investigated using different contact angle measurement techniques. The observed unique nonideal wetting was related to the APTES SAM structure, including surface hydrogen bond formation, the surface roughness, and the effect of water penetration. The contact angle decreased dramatically with the residence time on the APTES SAM surface, and a special contact angle hysteresis phenomenon was observed. The contact angle could be distorted by the calculation method used for the nonideal APTES SAM surface. Values calculated by the tangent-leaning method were thought to be more accurate and credible. Our findings demonstrated that static advancing contact angles were the most stable and credible for characterizing the APTES SAM surface wettability. PMID:21142166

Zeng, Xiangxuan; Xu, Guohua; Gao, Yuan; An, Yue

2011-01-27

380

Improving endothelialization on 316L stainless steel through wettability controllable coating by sol-gel technology  

NASA Astrophysics Data System (ADS)

Rapid endothelialization by surface coverage is considered as a way to increase blood compatibility of the vascular stent and reduce smooth muscle cell (SMC) mediated restenosis. Coatings on 316L stainless steels with different wettabilities and similar topographies were obtained through sol-gel process by regulating the proportions of tetraethoxysilane (TEOS) and methyltriethoxysilane (MTES). Adhesion and proliferation of vascular endothelial cells (EC) and SMC on these substrates have been evaluated by cell numbers, cell morphology, and expression of cytoskeletal protein. Results showed that EC and SMC responded differently to the coated surfaces. Enhanced endothelialization of bare 316L was found at the moderately hydrophilic coating (contact angle 45.3°) which exhibited effective inhibition of SMC and negligible influence on EC. These results are expected to lay foundation for the solution of the vascular restenosis which was mainly derived from the hyperplasia of SMC.

Wang, Mingqi; Wang, Yao; Chen, Yijie; Gu, Hongchen

2013-03-01

381

Fabrication of super-repellent cotton textiles with rapid reversible wettability switching of diverse liquids  

NASA Astrophysics Data System (ADS)

By in situ introducing polyaniline (PANI) and perfluorooctanoic acid (PFOA) to cotton fibers, normally hydrophilic and oleophilic cotton textile has easily turned superhydrophobic and highly oleophobic. This super-repellent cotton fabric exhibits a high contact angle (>150°) and low contact angle hysteresis, even with liquids possessing significantly low surface tension. The water or oil repellent property is ascribed to the combination of a dual-size surface roughness and low-surface-energy material. In particular, a reversible wettability switching of various low-surface-tension liquids on the PANI-fabric can be simultaneously observed, when it is doped with PFOA and de-doped with sodium hydroxide via a simple dipping method. This transition can be explained by the conversion of fluorine content and hydrophilic groups on the surface during the doping/dedoping process. Besides, this doping polymerization and dedoping process can slightly affect the mechanical strength of the cotton fabrics, even with harsh chemicals like acid and base.

Zhou, Xiaoyan; Zhang, Zhaozhu; Xu, Xianghui; Men, Xuehu; Zhu, Xiaotao

2013-07-01

382

Wettability in reactive Sn-base alloy/Ni-base metallic glass systems  

NASA Astrophysics Data System (ADS)

Fluxless wetting of a Ni-base metallic glass alloy with a nominal composition of Ni-7Cr-3.2B-4.5Si-3Fe (wt.%) by several Sn-base solders was investigated using a dispensed sessile drop method in a high vacuum at 523 K, and their interfacial microstructures were characterized. The results show that the wettability was in the sequence of Sn-51 wt.% In > Sn-37 wt.% Pb > Sn-57 wt.% Bi > Sn-0.7 wt.% Cu > Sn-3.0 wt.% Ag-0.5 wt.% Cu > pure Sn. The interface consisted of two distinct layers with the upper being the reaction layer and the lower the Sn-diffusion layer. For the Sn-0.7 wt.% Cu, Sn-3.0 wt.% Ag-0.5 wt.% Cu and Sn-51 wt.% In solders, the primary reaction products were (Cu,Ni)6Sn5, (Ni,Cu)3Sn4 and Ni3(Sn,In)4, respectively, while for the other solders, they were Ni3Sn4. The thickness of the reaction layer in the central area varied in the order of Sn-51 wt.% In > pure Sn > Sn-3.0 wt.% Ag-0.5 wt.% Cu ? Sn-0.7 wt.% Cu > Sn-57 wt.% Bi > Sn-37 wt.% Pb, which is likely related to the concentration and diffusion rate of Sn. Moreover, the interfacial reaction facilitated the crystallization of the amorphous Ni-base substrates adjacent to the reaction layer and the crystallization in turn promoted the diffusion of Sn toward the substrate. The mechanisms for the different wettability of these solders with the Ni-base amorphous alloy were discussed, and finally suitable solders were recommended for the joining of this amorphous material

Zhang, Lin-Yang; Shen, Ping; Qi, Yan; Jiang, Qi-Chuan

2013-07-01

383

Growth of hierarchical based ZnO micro/nanostructured films and their tunable wettability behavior  

NASA Astrophysics Data System (ADS)

Hierarchical zinc oxide (ZnO) micro/nanostructured thin films were grown onto as-prepared and different annealed ZnO seed layer films by a simple two step chemical process. A cost effective successive ionic layer adsorption and reaction (SILAR) method was employed to grow the seed layer films at optimal temperature (80 °C) and secondly, different hierarchical based ZnO structured thin films were deposited over the seed layered films by chemical bath deposition (CBD). The influence of seed layer on the structural, surface morphological, optical and wettability behavior of the ZnO thin films were systematically investigated. The XRD analysis confirms the high crystalline nature of both the seed layer and corresponding ZnO micro/nanostructured films with a perfect hexagonal structure oriented along (0 0 2) direction. The surface morphology revels a complex and orientated hierarchical based ZnO structured films with diverse shapes from plates to hexagonal rod-like crystal to tube-like structure and even much more complex needle-like shapes during secondary nucleation, by changing the seed layer conditions. The water contact angle (WCA) measurements on hierarchical ZnO structured films are completely examined to study its surface wettability behavior for its suitability in future self-cleaning application. Photoluminescence (PL) spectra of the ZnO structured film exhibit UV and visible emissions in the range of 420-500 nm. The present approach demonstrates its potential for low-temperature, large-scale, controlled synthesis of crystalline hierarchical ZnO nanostructures films.

Suresh Kumar, P.; Dhayal Raj, A.; Mangalaraj, D.; Nataraj, D.; Ponpandian, N.; Li, Lin; Chabrol, G.

2011-05-01

384

Electrochromic performance, wettability and optical study of copper manganese oxide thin films: Effect of annealing temperature  

NASA Astrophysics Data System (ADS)

In the present work, the nanostructured copper manganese oxide (CMO) thin films were prepared from acetate based sol-gel precursors and deposited on glass and indium tin oxide (ITO) substrates by dip-coating technique. The films were annealed at 300, 400 and 500 °C in ambient atmosphere. The effects of annealing temperature on structural, morphological, wettability, electrochromic and optical properties of CMO thin films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDX), water contact angle measurement (WCA), cyclic voltammetry (CV) measurements and ultraviolet-visible (UV-vis) spectrophotometery. The presence of mixed oxide phases comprising of copper manganese oxide (CuMn2O4) and manganese oxide at different annealing temperature was confirmed by XRD patterns. The results showed that the Mn3O4 phase has been changed to Mn2O3 when the annealing temperature is increased from 300 to 500 °C. The FESEM images indicated that the granular surface morphology was sensitive to annealing temperature. EDX studies indicated that the thin films contained O, Mn and Cu species. Wettability studies showed that the water contact angle of the nanostructured CMO thin films coated on glass substrates was influenced by the variation of annealing temperature and the surface nature of thin films was changed from hydrophilic to hydrophobic. The results of CVs measurement indicated that the anodic and cathodic charge density and capacitance of all CMO samples decreased with increasing scan rate in potential range of -1-1 eV. Also, the annealed CMO thin film at 500 °C showed better electrochromic performance with respect to other samples at lower scan rate. The thickness, refractive index, extinction coefficient and optical band gap of thin films coated on glass substrates were calculated from reflectance and transmittance spectra using an iterative numerical method. The optical band gap of nanostructured CMO thin films increased with increasing annealing temperature.

Falahatgar, S. S.; Ghodsi, F. E.; Tepehan, F. Z.; Tepehan, G. G.; Turhan, ?.

2014-01-01

385

Wettability and osteoblast cell response modulation through UV laser processing of nylon 6,6  

NASA Astrophysics Data System (ADS)

With an ageing population the demand for cheap, efficient implants is ever increasing. Laser surface treatment offers a unique means of varying biomimetic properties to determine generic parameters to predict cell responses. This paper details how a KrF excimer laser can be employed for both laser-induced patterning and whole area irradiative processing to modulate the wettability characteristics and osteoblast cell response following 24 h and 4 day incubation. Through white light interferometry (WLI) it was found that the surface roughness had considerably increased by up to 1.5 ?m for the laser-induced patterned samples and remained somewhat constant at around 0.1 ?m for the whole area irradiative processed samples. A sessile drop device determined that the wettability characteristics differed between the surface treatments. For the patterned samples the contact angle, ?, increased by up to 25° which can be attributed to a mixed-state wetting regime. For the whole area irradiative processed samples ? decreased owed to an increase in polar component, ?P. For all samples ? was a decreasing function of the surface energy. The laser whole area irradiative processed samples gave rise to a distinct correlative trend between the cell response, ? and ?P. However, no strong relationship was determined for the laser-induced patterned samples due to the mixed-state wetting regime. As a result, owed to the relationships and evidence of cell differentiation one can deduce that laser whole area irradiative processing is an attractive technology for employment within regenerative medicine to meet the demands of an ageing population.

Waugh, D. G.; Lawrence, J.

2011-08-01

386

A Process for Producing Highly Wettable Aluminum 6061 Surfaces Compatible with Hydrazine  

NASA Technical Reports Server (NTRS)

NASA's Global Precipitation Measurement (GPM) mission is an ongoing Goddard Space Flight Center (GSFC) project whose basic objective is to improve global precipitation measurements. The space-based portion of the mission architecture consists of a primary or core spacecraft and a constellation of NASA and contributed spacecrafts. The efforts described in this paper refer to the core spacecraft (hereafter referred to as simply GPM) which is to be fabricated at GSFC. It has been decided that the GPM spacecraft is to be a "design-for-demise-spacecraft." This requirement resulted in the need for a propellant tank that would also demise or ablate to an appropriate degree upon re-entry. Composite overwrapped aluminum lined propellant tanks with aluminum propellant management devices (PMD) were shown by analyses to demise and thus became the baseline configuration for GPM. As part of the GPM tank development effort, long term compatibility and wettability testing with hydrazine was performed on Al6061 and 2219 coupons fabricated and cleaned by conventional processes. Long term compatibility was confirmed. However, the wettability of the aluminum as measured by contact angle produced higher than desired angles (greater than 30 deg.) with excessive scatter. The availability of PMD materials exhibiting consistently low contact angles aids in the design of simple PMDs. Two efforts performed by Angeles Crest Engineering and funded by GSFC were undertaken to reduce the risk of using aluminum for the GPM PMD. The goal of the first effort was to develop a cleaning or treatment process to produce consistently low contact angles. The goal of the second effort was to prove via testing that the processed aluminum would retain compatibility with hydrazine and retain low contact angle after long term exposure to hydrazine. Both goals were achieved. This paper describes both efforts and the results achieved.

Moore, N. R.; Ferraro, N. W.; Yue, A. F.; Estes, R. H.

2007-01-01

387

Pulmonary capillary hemangiomatosis: a rare cause of pulmonary hypertension.  

PubMed

Pulmonary capillary hemangiomatosis is a rare cause of pulmonary hypertension characterized by extensive proliferation of pulmonary capillaries within alveolar septae. Clinical presentation is nonspecific and includes dyspnea, cough, chest pain, and fatigue. Radiology shows diffuse centrilobular ground-glass opacities. Pulmonary capillary hemangiomatosis is clinically and radiographically indistinguishable from peripheral venoocclusive disease, making microscopic diagnosis essential. Histologically, pulmonary capillary hemangiomatosis shows an abnormal proliferation of small, thin-walled capillaries that expand the alveolar septae. The endothelial cells that comprise these lesions are cytologically bland and show no mitotic activity. Pulmonary capillary hemangiomatosis is important to recognize because prostacyclin therapy, a mainstay in the treatment of pulmonary hypertension, has been reported to cause sudden respiratory distress and death in these patients. Prognosis of this disease remains poor, and the only definitive treatment is lung transplantation. PMID:25611112

O'Keefe, Mary C; Post, Miriam D

2015-02-01

388

Means and method for capillary zone electrophoresis with laser-induced indirect fluorescence detection  

DOEpatents

A means and method for capillary zone electrphoresis with laser-induced indirect fluorescence detection. A detector is positioned on the capillary tube of a capillary zone electrophoresis system. The detector includes a laser which generates a laser beam which is imposed upon a small portion of the capillary tube. Fluorescence of the elutant electromigrating through the capillary tube is indirectly detected and recorded.

Yeung, Edward S. (Ames, IA); Kuhr, Werner G. (Riverside, CA)

1996-02-20

389

Means and method for capillary zone electrophoresis with laser-induced indirect fluorescence detection  

DOEpatents

A means and method for capillary zone electrphoresis with laser-induced indirect fluorescence detection. A detector is positioned on the capillary tube of a capillary zone electrophoresis system. The detector includes a laser which generates a laser beam which is imposed upon a small portion of the capillary tube. Fluorescence of the elutant electromigrating through the capillary tube is indirectly detected and recorded.

Yeung, Edwards (Ames, IA); Kuhr, Werner G. (Riverside, CA)

1991-04-09

390

Applicability of Washburn capillary rise for determining contact angles of powders/porous materials.  

PubMed

The Washburn capillary rise (WCR) technique has been widely utilized for determining contact angles of powders or porous materials; however, there are concerns regarding powder size and powder packing, especially for materials that exhibit large contact angle hysteresis. In this paper, some of these concerns were addressed. Due to the large water contact angle hysteresis on flat nylon 6/6 films, these films were ground into powders of different sizes and then used as model packing materials. The powders were packed in glass tubes to result in various packing structures that affected the penetration (i.e. advancing) rate of the test liquids. While all advancing contact angles obtained from WCR were found to be overestimated, more reasonable values were resulted when relatively large powders (e.g. 500-2000 ?m) were used to pack the tubes. With larger powders, the packing contained bigger voids and consequently lead to slower penetration rates of the liquids, hence a relatively smaller advancing contact angle. The smaller advancing contact angle obtained from the slower advancing rate was also observed by using the sessile drop method. To verify the applicability of using large powders (500-2000 ?m) for contact angle determination by using WCR, the advancing water contact angles of a bacterial cellulose/alginate composite sponge (BCA) with and without UV/ozone treatment were measured. The results showed that by using relatively large powders, WCR could be applied to obtain a reasonable advancing contact angle and assess the wettability change of complex porous materials. PMID:23484765

Kirdponpattara, Suchata; Phisalaphong, Muenduen; Newby, Bi-min Zhang

2013-05-01

391

Surface-tension-driven liquid liquid displacement in a capillary  

Microsoft Academic Search

This paper presents theoretical and experimental studies of the surface-tension-driven, two-immiscible liquid-liquid displacement in a horizontal capillary. Using the dynamic contact angle approach, a one-dimensional mathematical model is developed to describe the capillary displacement of a fixed liquid column by another liquid that continuously flows into the capillary by surface tension. Experiments for a water column displaced by silicon oil

W. K. Chan; C. Yang

2005-01-01

392

Long-Term Culture of Capillary Endothelial Cells  

Microsoft Academic Search

Capillary endothelial cells from rats, calves, and humans, have been carried in long-term culture. Bovine capillary endothelial cells have been cloned and maintained by serial passage for longer than 8 months. This prolonged culture was accomplished by using tumor-conditioned medium, gelatin-coated plates, and a method of enriching cells in primary culture. Cultured bovine capillary endothelial cells produce Factor VIII antigen

Judah Folkman; Christian C. Haudenschild; Bruce R. Zetter

1979-01-01

393

Recent advances of capillary electrophoresis in pharmaceutical analysis  

Microsoft Academic Search

This review covers recent advances of capillary electrophoresis (CE) in pharmaceutical analysis. The principle, instrumentation,\\u000a and conventional modes of CE are briefly discussed. Advances in the different CE techniques (non-aqueous CE, microemulsion\\u000a electrokinetic chromatography, capillary isotachophoresis, capillary electrochromatography, and immunoaffinity CE), detection\\u000a techniques (mass spectrometry, light-emitting diode, fluorescence, chemiluminescence, and contactless conductivity), on-line\\u000a sample pretreatment (flow injection) and chiral separation

Leena Suntornsuk

2010-01-01

394

Ionization waves in electron-beam-assisted, shielded capillary discharge  

Microsoft Academic Search

A theory of propagation of cathode-directed ionization waves during the early stages of an electrical breakdown in a shielded, low-pressure capillary is developed. The discharge process occurs due to the ionization of the low-density gas in the capillary by an electron beam that is emanating from a hollow cathode. Due to the strong electric field in the capillary the electrons

I. Rutkevich; M. Mond; Y. Kaufman; P. Choi; M. Favre

2000-01-01

395

Capillary priming characteristics of a high capacity dual passage heat pipe  

NASA Technical Reports Server (NTRS)

A parametric study of the forces governing the liquid-vapor interface was performed for the purpose of determining the capillary priming characteristics of Grumman's dual passage monogroove heat pipe when subjected to low-g or zero-g conditions. The static liquid-vapor interface configuration was determined through minimization of the free surface energies and a mathematical model and computer program which describe the time to prime was developed. Modeling predictions confirmed expectations of proper priming action and established the criteria for sizing of the liquid and vapor channels.

Peterson, G. P.

1982-01-01

396

Capillary-Condenser-Pumped Heat-Transfer Loop  

NASA Technical Reports Server (NTRS)

Heat being transferred supplies operating power. Capillary-condenser-pumped heat-transfer loop similar to heat pipe and to capillary-evaporator-pumped heat-transfer loop in that heat-transfer fluid pumped by evaporation and condensation of fluid at heat source and sink, respectively. Capillary condenser pump combined with capillary evaporator pump to form heat exchanger circulating heat-transfer fluids in both loops. Transport of heat more nearly isothermal. Thermal stress in loop reduced, and less external surface area needed in condenser section for rejection of heat to heat sink.

Silverstein, Calvin C.

1989-01-01

397

Development of tracking detectors based on capillaries with liquid scintillator  

NASA Astrophysics Data System (ADS)

Capillaries with a liquid scintillator used for high resolution tracking detectors have been investigated. The highest scintillation efficiency, 1.5 times higher than that of a standard polystyrene scintillator, has been attained for the solution of 1-methylnaphthalene with pyrasoline type dye MDP. The time properties of this liquid scintillator and locality of light emission have been studied. Light attenuations in quartz capillaries of different diameters have been measured. For the optimal concentration of MDP the attenuation lengths for capillaries of 30 and 60 ?m in diameter were 41 cm and 53 cm, respectively. For high resolution tracking detectors capillaries with a liquid scintillator are quite competitive with plastic fibres.

Golovkin, S. V.; Gorin, A. M.; Kulichenko, A. V.; Kushnirenko, A. E.; Peresypkin, A. I.; Pyshchev, A. I.; Rykalin, V. I.; Zaichenko, A. A.

1991-07-01

398

The study of polyoxometalates formation using capillary zone electrophoresis.  

PubMed

The formation process of polyoxometalates [PMo12 O40 ](3-) and [PMo12 - x Vx O40 ](-3-x) has been studied in aqueous solutions of 0.1 M malonate buffer at pH 2.8-3.0 using CZE. Two different approaches, pre-capillary and in-capillary, were examined and compared. In precapillary mode, the reaction mixture of the reactants and reaction products was injected into the capillary followed by the separation procedure. In in-capillary mode, the sequential input of the reagents and running electrolyte into the capillary and the species separation occurs simultaneously. The optimal parameters of in-capillary separation were established as functions of applied voltage and the length of the intermediate buffer zone between the reagents in the capillary. As a result the best-compromise conditions for the separation of the mixtures containing the reactants, intermediates, and reaction products, in order to achieve the best efficiency, symmetry, and peak areas, were achieved at -18 kV and the input parameter of 900 mbar·s. It was also shown that in-capillary mode is more informative than pre-capillary mode for studying the complex compound formation process. PMID:24981023

Zdanov, Artem A; Shuvaeva, Olga V

2014-09-01

399

Capillary rarefaction in treated and untreated hypertensive subjects.  

PubMed

This study aimed to determine if capillary rarefaction is detectable and associated with endothelial dysfunction in persons with mild systolic blood pressure (SBP) elevation. Capillary density and endothelial function were quantified for 150 nondiabetic participants, grouped by blood pressure (BP) as normotensive, untreated high BP, and treated high BP. Structural capillary rarefaction measures were not different between the three groups. Functional capillary rarefaction measures were significantly lower in both high BP groups compared to normotensives, and correlated inversely with endothelial function. The study findings indicate that the hypertensive vascular pathologic process is already underway at modest levels of blood pressure elevation. PMID:19124411

Cheng, Cynthia; Daskalakis, Constantine; Falkner, Bonita

2008-04-01

400

Mass action  

NSDL National Science Digital Library

In the first part of this video, we derive the law of mass action from one example of a picture of molecular collisions. For this course, we use the "law of mass action" to refer to an idea that chemical reaction kinetic rates can be expressed using products of the abundances of reactants raised to exponents. Studying cooperativity and Hill functions in the second part of the video allows us to investigate a simple example of bistability in the third video segment.

2013-06-21

401

Enzyme Action  

NSDL National Science Digital Library

In this activity that can be used as a lab or demonstration, learners use Lactaid® and lactose to demonstrate the concept of enzyme action. Learners test a drop of milk and Lactaid® for the presence of glucose using glucose test paper. Learners also discover the color range of glucose test paper readings. In addition, learners construct paper models to help visualize enzyme action.

Crumlish, Jane

2009-01-01

402

Action perception predicts action performance  

PubMed Central

Everyday action impairments often are observed in demented older adults, and they are common potential barriers to functional independence. We evaluated whether the ability to segment and efficiently encode activities is related to the ability to execute activities. Further, we evaluated whether brain regions important for segmentation also were important for action performance. Cognitively healthy older adults and those with very mild or mild dementia of the Alzheimer's type watched and segmented movies of everyday activities and then completed the Naturalistic Action Test. Structural MRI was used to measure volume in the dorsolateral prefrontal cortex (DLPFC), medial temporal lobes (MTL), posterior cortex, and anterior cingulate cortex (ACC). Dementia status and the ability to segment everyday activities strongly predicted naturalistic action performance, and MTL volume largely accounted for this relationship. In addition, the current results supported the Omission-Commission Model: Different cognitive and neurological mechanisms predicted different types of action error. Segmentation, dementia severity, and MTL volume predicted everyday omission errors, DLPFC volume predicted commission errors, and ACC volume predicted action additions. These findings suggest that event segmentation may be critical for effective action production, and that the segmentation and production of activities may recruit the same event representation system. PMID:23851113

Bailey, Heather R.; Kurby, Christopher A.; Giovannetti, Tania; Zacks, Jeffrey M.

2013-01-01

403

Capillary-Driven Heat Transfer Experiment: Keeping It Cool in Space  

NASA Technical Reports Server (NTRS)

Capillary-pumped loops (CPL's) are devices that are used to transport heat from one location to another--specifically to transfer heat away from something. In low-gravity applications, such as satellites (and possibly the International Space Station), CPL's are used to transfer heat from electrical devices to space radiators. This is accomplished by evaporating one liquid surface on the hot side of the CPL and condensing the vapor produced onto another liquid surface on the cold side. Capillary action, the phenomenon that causes paper towels to absorb spilled liquids, is used to "pump" the liquid back to the evaporating liquid surface (hot side) to complete the "loop." CPL's require no power to operate and can transfer heat over distances as large as 30 ft or more. Their reliance upon evaporation and condensation to transfer heat makes them much more economical in terms of weight than conventional heat transfer systems. Unfortunately, they have proven to be unreliable in space operations, and the explanation for this unreliability has been elusive. The Capillary-Driven Heat Transfer (CHT) experiment is investigating the fundamental fluid physics phenomena thought to be responsible for the failure of CPL's in low-gravity operations. If the failure mechanism can be identified, then appropriate design modifications can be developed to make capillary phase-change heat-transport devices a more viable option in space applications. CHT was conducted onboard the Space Shuttle Columbia during the first Microgravity Science Laboratory (MSL-1) mission, STS-94, which flew from July 1 to 17, 1997. The CHT glovebox investigation, which was conceived by Dr. Kevin Hallinan and Jeffrey Allen of the University of Dayton, focused on studying the dynamics associated with the heating and cooling at the evaporating meniscus within a capillary phase-change device in a low-gravity environment. The CHT experimental hardware was designed by a small team of engineers from Aerospace Design & Fabrication (ADF), the NASA Lewis Research Center, and the University of Dayton. The hardware consisted of two experiment modules that each contained an instrumented test loop (idealized capillary-pumped loop), a base unit for power conversion and backlighting, a display unit with 15 LED's (light-emitting diodes) to display temperatures, pressure, heater power, and time, a control unit to select heaters and heater settings, a cooling fan, and associated cables.

Lekan, Jack F.; Allen, Jeffrey S.

1998-01-01

404

Separate effects of surface roughness, wettability and porosity on boiling heat transfer and critical heat flux and optimization of boiling surfaces  

E-print Network

The separate effects of surface wettability, porosity, and roughness on critical heat flux (CHF) and heat transfer coefficient (HTC) were examined using carefully-engineered surfaces. All test surfaces were prepared on ...

O'Hanley, Harrison Fagan

2012-01-01

405

Simulating the evolution of an ethanol and gasoline source zone within the capillary fringe  

NASA Astrophysics Data System (ADS)

Blending of ethanol into gasoline as a fuel oxygenate has created the scenario where inadvertent releases of E95 into soil previously contaminated by gasoline may remobilize these pre-existing NAPLs and lead to higher dissolved hydrocarbon (BTEX) concentrations in groundwater. We contribute to the development of a risk-based corrective action framework addressing this issue by conducting two laboratory experiments involving the release of ethanol into a gasoline source zone established in the capillary fringe. We then develop and apply the numerical model CompFlow Bio to replicate three specific experimental observations: (1) depression of the capillary fringe by the addition of the gasoline fuel mixture due to a reduction in the surface tension between the gas and liquid phases, (2) further depression of the capillary fringe by the addition of ethanol, and (3) remobilization of the gasoline fuel mixture LNAPL source zone due to the cosolvent behaviour of ethanol in the presence of an aqueous phase, as well as a reduction in the interfacial tension between the aqueous/non-aqueous phases due to ethanol. While the simulated collapse of the capillary fringe was not as extensive as that which was observed, the simulated and observed remobilized non-aqueous phase distributions were in agreement following ethanol injection. Specifically, injection of ethanol caused the non-aqueous phase to advect downwards toward the water table as the capillary fringe continued to collapse, finally collecting on top of the water table in a significantly reduced area exhibiting higher saturations than observed prior to ethanol injection. Surprisingly, the simulated ethanol and gasoline aqueous phase plumes were uniform despite the redistribution of the source zone. Dissolution of gasoline into the aqueous phase was dramatically increased due to the cosolvency effect of ethanol on the non-aqueous phase source zone. We advocate further experimental studies focusing on eliminating data gaps identified here, as well as field-scale experiments to address issues associated with ethanol-BTEX biodegradation and sorption within the development of a risk-based corrective action framework.

Yu, Soonyoung; Freitas, Juliana G.; Unger, Andre J. A.; Barker, James F.; Chatzis, John

2009-02-01

406

Simulating the evolution of an ethanol and gasoline source zone within the capillary fringe.  

PubMed

Blending of ethanol into gasoline as a fuel oxygenate has created the scenario where inadvertent releases of E95 into soil previously contaminated by gasoline may remobilize these pre-existing NAPLs and lead to higher dissolved hydrocarbon (BTEX) concentrations in groundwater. We contribute to the development of a risk-based corrective action framework addressing this issue by conducting two laboratory experiments involving the release of ethanol into a gasoline source zone established in the capillary fringe. We then develop and apply the numerical model CompFlow Bio to replicate three specific experimental observations: (1) depression of the capillary fringe by the addition of the gasoline fuel mixture due to a reduction in the surface tension between the gas and liquid phases, (2) further depression of the capillary fringe by the addition of ethanol, and (3) remobilization of the gasoline fuel mixture LNAPL source zone due to the cosolvent behaviour of ethanol in the presence of an aqueous phase, as well as a reduction in the interfacial tension between the aqueous/non-aqueous phases due to ethanol. While the simulated collapse of the capillary fringe was not as extensive as that which was observed, the simulated and observed remobilized non-aqueous phase distributions were in agreement following ethanol injection. Specifically, injection of ethanol caused the non-aqueous phase to advect downwards toward the water table as the capillary fringe continued to collapse, finally collecting on top of the water table in a significantly reduced area exhibiting higher saturations than observed prior to ethanol injection. Surprisingly, the simulated ethanol and gasoline aqueous phase plumes were uniform despite the redistribution of the source zone. Dissolution of gasoline into the aqueous phase was dramatically increased due to the cosolvency effect of ethanol on the non-aqueous phase source zone. We advocate further experimental studies focusing on eliminating data gaps identified here, as well as field-scale experiments to address issues associated with ethanol-BTEX biodegradation and sorption within the development of a risk-based corrective action framework. PMID:19110339

Yu, Soonyoung; Freitas, Juliana G; Unger, Andre J A; Barker, James F; Chatzis, John

2009-02-27

407

Effective viscosity of magnetic nanofluids through capillaries.  

PubMed

The simultaneous effect of magnetic field and temperature on the capillary viscosity of magnetic nanofluid is an important parameter for a new class of applications such as nanoduct flow, nanomotors, micro- and nanofluidic devices, for transformer cooling, magnetic targeted drug delivery, etc. The effective viscosity of a nanofluid is explained based on the rotation of the particles and the effect of torque on it due to an externally applied magnetic field. Two types of fluids are used here, temperature-sensitive and non-temperature-sensitive magnetic nanofluids. In both types of fluids, decrease in effective viscosity with temperature is observed, but in both cases the mechanism for the decrement is quite different. One is due to temperature dependence of the magnetic moment and the other is due to removal of the secondary surfactant. For temperature-sensitive magnetic nanofluids, a Curie temperature of ~80 °C is extracted from this study. For non-temperature-sensitive magnetic nanofluids ~65% of the secondary surfactant is removed for a change in temperature, ?T = 40 °C. This is analogous with removal of a drug from magnetic particles for targeted drug delivery. Further, a linear dependence of effective viscosity with different capillary size and ? (angle between magnetic field and flow direction, ??[0,?/2]) is also observed. This linear dependence can also be a good approximation for the study of magnetic drug targeting, as in the human body the capillaries are of different sizes, and the externally applied magnetic field is not always parallel or perpendicular to the drug flow direction. PMID:22463326

Patel, Rajesh

2012-02-01

408

Microfluidic Device to Culture 3D In Vitro Human Capillary Networks  

E-print Network

Microfluidic Device to Culture 3D In Vitro Human Capillary Networks Monica L. Moya, Luis F. Alonzo human capillaries. Keywords: Microfluidic platform, Microenviroment, Perfused capillary networks perfusion. To address these limitations, various research groups have explored the use of microfluidic

George, Steven C.

409

Journal of Chromatography B, 841 (2006) 313 Capillary electromigration methods for the study of collagen  

E-print Network

Journal of Chromatography B, 841 (2006) 3­13 Review Capillary electromigration methods, micellar electrokinetic chromatography as well as combinations of HPLC and capillary electrophoresis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2. Micellar electrokinetic chromatography and capillary gel electrophoresis

Miksik, Ivan

410

Antifungal activity of Ferulago capillaris essential oil against Candida, Cryptococcus, Aspergillus and dermatophyte species.  

PubMed

This study evaluates the composition, antifungal activity and mechanism of action of the essential oil of Ferulago capillaris (Link ex Spreng.) Cout. and its main components, limonene and ?-pinene, against clinically relevant yeasts and moulds. Essential oil from the plant's aerial parts was obtained by hydrodistillation and analysed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC-MS). Essential oil showed high contents of limonene (30.9%) and ?-pinene (35.8%). Minimum inhibitory concentrations (MICs) were measured according to the reference Clinical and Laboratory Standards Institute (CLSI) broth macrodilution protocols. Cell suspensions were subcultured in solid medium and the minimum fungicidal concentrations (MFCs) were rendered. The effect of essential oil on germ tube formation, mitochondrial function and ergosterol biosynthesis was investigated. Essential oil and ?-pinene displayed low and similar MIC and MFC values against tested organisms (0.08 to 5.0 ?L/mL), while limonene showed a weaker activity (0.32 to 20 ?L/mL). Essential oil inhibited germ tube formation at sub-inhibitory concentrations on Candida albicans. The exposure of C. albicans to the essential oil resulted in impairment of mitochondrial functions in a dose-dependent manner. No difference in ergosterol content was observed in essential oil-treated C. albicans. F. capillaris and ?-pinene display a broad fungicidal activity. The fungicidal activity of F. capillaris on C. albicans can be related to an induced oxidative stress which affects enzymes activity and the membrane potential of mitochondria. The essential oil of F. capillaris was shown to have potential for use in the development of clinically useful therapeutic preparations, particularly for topical application in the management of superficial mycoses. PMID:23619574

Pinto, E; Hrimpeng, K; Lopes, G; Vaz, S; Gonçalves, M J; Cavaleiro, C; Salgueiro, L

2013-10-01

411

Microfabricated capillary array electrophoresis device and method  

DOEpatents

A capillary array electrophoresis (CAE) micro-plate with an array of separation channels connected to an array of sample reservoirs on the plate. The sample reservoirs are organized into one or more sample injectors. One or more waste reservoirs are provided to collect wastes from reservoirs in each of the sample injectors. Additionally, a cathode reservoir is also multiplexed with one or more separation channels. To complete the electrical path, an anode reservoir which is common to some or all separation channels is also provided on the micro-plate. Moreover, the channel layout keeps the distance from the anode to each of the cathodes approximately constant.

Simpson, Peter C. (Oakland, CA); Mathies, Richard A. (Moraga, CA); Woolley, Adam T. (Belmont, MA)

2000-01-01

412

Subsidence and capillary effects in chalks  

E-print Network

Based on the concepts of the mechanics of unsaturated soils where capillary phenomena arise between the wetting fluid (water) and the non-wetting one (air), the subsidence of chalks containing oil (non-wetting fluid) during water injection (wetting fluid) is analysed. It is shown that the collapse phenomenon of unsaturated soils under wetting provides a physical explanation and a satisfactory prediction of the order of magnitude of the subsidence of the chalk. The use of a well established constitutive model for unsaturated soils allows a description of the hydro-mechanical history of the chalk, from its deposition to the oil exploitation.

Delage, Pierre; Cui, Yu Jun

2008-01-01

413

Capillary Filling of Anodized Alumina Nanopore Arrays  

E-print Network

The filling behavior of a room temperature solvent, perfluoromethylcyclohexane, in approximately 20 nm nanoporous alumina membranes was investigated in situ with small angle x-ray scattering. Adsorption in the pores was controlled reversibly by varying the chemical potential between the sample and a liquid reservoir via a thermal offset, $\\Delta$T. The system exhibited a pronounced hysteretic capillary filling transition as liquid was condensed into the nanopores. These results are compared with Kelvin-Cohan theory, with a modified Derjaguin approximation, as well as with predictions by Cole and Saam.

K. J. Alvine; O. G. Shpyrko; P. S. Pershan; K. Shin; T. P. Russell

2006-12-05

414

Capillary Filling of Anodized Alumina Nanopore Arrays  

SciTech Connect

The filling behavior of a room temperature solvent, perfluoromethylcyclohexane, in approximately 20 nm nanoporous alumina membranes was investigated in situ with small angle x-ray scattering. Adsorption in the pores was controlled reversibly by varying the chemical potential between the sample and a liquid reservoir via a thermal offset, {delta}T. The system exhibited a pronounced hysteretic capillary filling transition as liquid was condensed into the nanopores. These results are compared with Kelvin-Cohan theory, with a modified Derjaguin approximation, as well as with predictions by Cole and Saam.

Alvine, Kyle J. [Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Shpyrko, Oleg G. [Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Pershan, Peter S. [Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); Shin, Kyusoon [School of Chemical and Biological Engineering, Seoul National University, Seoul, Republic of Korea (Korea, Republic of); Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003 (United States); Russell, Thomas P. [Department of Polymer Science and Engineering, University of Massachusetts, Amherst, Massachusetts 01003 (United States)

2006-10-27

415

Dynamics of capillary drying in water.  

PubMed

We use atomistic simulations to address the question when capillary evaporation of water confined in a hydrocarbonlike slit is kinetically viable. Activation barriers and absolute rates of evaporation are estimated using open ensemble Monte Carlo-umbrella sampling and molecular dynamics simulations. At ambient conditions, the evaporation rate in a water film four molecular diameters thick is found to be of the order 10(5)(nm(2) s)(-1), meaning that water readily evaporates. Films more than a few nanometers thick will persist in a metastable liquid state. Dissolved atmospheric gas molecules do not significantly decrease the activation barrier. PMID:12633299

Leung, Kevin; Luzar, Alenka; Bratko, Dusan

2003-02-14

416

Folding of capillary threads in microfluidic networks  

NASA Astrophysics Data System (ADS)

We examine the evolution of the folding instability of lubricated viscous threads in straight microchannels. Folds having a uniform wavelength can be produced using a diverging microchannel connected to three channels in parallel. This design allows for the detailed experimental study of the influence of viscosity contrast, interfacial properties, and flow rates on the structure of miscible and immiscible micro-threads. In particular, we focus on the spatial damping of the amplitude of sinuous capillary threads due to interfacial tension effects. This study shows methods for the interfacial control of high-viscosity fluids in microfluidic systems.

Cubaud, Thomas; Darvishi, Samira

2009-11-01

417

The permeability of single capillaries to potassium ions  

PubMed Central

This paper reports a description of methods for determining the diffusional permeability to potassium ions of single capillaries in the frog mesentery. By means of micropipettes, injections or infusions were delivered into a single capillary. The subsequent concentration variations in and about the capillary were followed with K(+)-sensitive microelectrodes. A theoretical analysis is provided which give a quantitative frame of reference for evaluating the observed time-concentration curves in terms of capillary permeability. The advantage of single capillary studies is that the surface area through which diffusion occurs is known as is the concentration difference across the capillary membrane. Three different techniques are: (a) the “single injection” method which represents an application of the indicator diffusion technique where a high-K(+) bolus is injected into a single capillary; (b) the “sack” method which determines the rate of K(+) disappearance from within and immediately outside an occluded capillary segment, after a brief increase in intracapillary K(+) concentration; and (c) the “interstitial diffusion” method which records time and spatial distribution of K(+) in the interstitial space after a step-change in intracapillary K(+) concentration. The methods gave an average potassium permeability of the capillary membrane of 67x10(-5) cm s(-1) (SD: 23, n=26) at room temperature. These figures are clearly higher than those previously reported in mammalian capillary studies using whole-organ techniques. In terms of the pappenheimer pore model, this estimate of capillary permeability is consistent with the behavior of a membrane with a thickness of 1.0 ?m which possesses equivalent pores with a radius of 110 A, a fractional pore area of 0.3 percent, and a pore density of 8 ?m(-2). PMID:641520

Crone, C; Frokjaer-Jensen, J; Friedman, JJ; Christensen, O

1978-01-01

418

Improved Modeling and Understanding of Diffusion-Media Wettability on Polymer-Electrolyte-Fuel-Cell Performance  

SciTech Connect

A macroscopic-modeling methodology to account for the chemical and structural properties of fuel-cell diffusion media is developed. A previous model is updated to include for the first time the use of experimentally measured capillary pressure -- saturation relationships through the introduction of a Gaussian contact-angle distribution into the property equations. The updated model is used to simulate various limiting-case scenarios of water and gas transport in fuel-cell diffusion media. Analysis of these results demonstrate that interfacial conditions are more important than bulk transport in these layers, where the associated mass-transfer resistance is the result of higher capillary pressures at the boundaries and the steepness of the capillary pressure -- saturation relationship. The model is also used to examine the impact of a microporous layer, showing that it dominates the response of the overall diffusion medium. In addition, its primary mass-transfer-related effect is suggested to be limiting the water-injection sites into the more porous gas-diffusion layer.

Weber, Adam

2010-03-05

419

Odor-evoked oxygen consumption by action potential and synaptic transmission in the olfactory bulb  

PubMed Central

The relationship between metabolism of neuronal activity, microvascular organization and blood flow dynamics is critical for interpreting functional brain imaging. Here we used the rat dorsal olfactory bulb as a model to determine in vivo the correlation between action potential propagation, synaptic transmission, oxygen consumption and capillary density during odor stimulation. We find that capillary lumen occupies about 3 % of the glomerular volume, where synaptic transmission occurs, and only 0.1 % of the overlying nerve layer. In glomeruli, odor triggers a local early decrease in tissue oxygen partial pressure that results principally from dendritic activation rather than from firing of axon terminals, transmitter release or astrocyte activation. In the nerve layer, action potential propagation does not generate local changes in tissue oxygen partial pressure. We conclude that capillary density is tightly correlated with the oxidative metabolism of synaptic transmission, and suggest that action potential propagation operates mainly anaerobically. PMID:19193889

Lecoq, Jérôme; Tiret, Pascale; Najac, Marion; Shepherd, Gordon M.; Greer, Charles A.; Charpak, Serge

2009-01-01

420

Effect of deposition parameters on the wettability and microstructure of superhydrophobic films with hierarchical micro-nano structures.  

PubMed

Superhydrophobic films with hierarchical micro-nano structures were deposited on glass substrates by solution immersion method from a solution containing cobalt chloride, urea and cetyl trimethyl ammonium bromide (CTAB). Subsequently the films were hydrophobized with a low surface energy material like octadecanoic acid under ambient conditions resulting in superhydrophobic surfaces with water contact angle (WCA) of about 168° and contact angle hysteresis of 1°. The effect of deposition parameters such as solution composition, temperature, deposition time and alkanoic acid treatment on surface morphology and wettability of the films was studied. Mechanism of formation of cobalt chloride carbonate hydroxide film is discussed. Addition of CTAB to the solution resulted in a change in the surface morphology of the deposited films with flower-like structures. The wettability of films obtained under different process conditions was correlated to surface roughness using Wenzel and Cassie models. PMID:21864844

Basu, Bharathibai J; Manasa, J

2011-11-15

421

Use of a high magnetic field to visualize fluids and to study wettability in porous media by MRI  

SciTech Connect

Magnetic Resonance Imaging (MRI) is very useful for core analysis because it gives information related to petrophysical parameters: porosity and fluid saturations. The authors have used a high magnetic field of 9.4 Tesla to study fluid distributions in porous media. The use of high magnetic field coupled with strong gradients (up to 20 G/cm) enable the authors to produce images with a good resolution and to obtain very thin slices. The different applications studied are visualization of oil and water distributions during a flooding experiment, and study of wettability by NMR and MRI. For this last application, the authors have investigated to decouple the influence of pore size distribution and wettability in relaxation parameters.

Chardaire-Riviere, C.; Roussel, J.C. [Institut Francais du Petrole, Rueil-Malmaison (France)

1993-12-31

422

Fractal modeling for capillary flow through fiber bundle  

Microsoft Academic Search

Moisture transport in fiber assembly is one of the critical factors affecting physiological comfort. It is useful to model bundle structure for understanding capillary flow in complex geometries representative of the void spaces formed between fibers. This paper investigates the capillary rise in vertical fiber bundles. Regarding fiber bundles as a porous media, a mathematical model was developed by using

2012-01-01

423

Fractal modeling for capillary flow through fiber bundle  

Microsoft Academic Search

Moisture transport in fiber assembly is one of the critical factors affecting physiological comfort. It is useful to model bundle structure for understanding capillary flow in complex geometries representative of the void spaces formed between fibers. This paper investigates the capillary rise in vertical fiber bundles. Regarding fiber bundles as a porous media, a mathematical model was developed by using

2011-01-01

424

Rapid vaporization of subcooled liquid in a capillary structure  

E-print Network

for rapid vaporization of subcooled liquid in a capillary structure. The process consists of a low-thermal-conductivity thermal conductivity of the capillary structure and the presence of the extremely steep temperature generator consists of a low-thermal-conductivity porous wick, heated from a downward-facing grooved heating

Zhao, Tianshou

425

Comment on `Nanoscale water capillary bridges under deeply negative  

E-print Network

saturated vapor pressure Psat. Because of the cohesion forces between particles, the pressure can evenComment on `Nanoscale water capillary bridges under deeply negative pressure' [Chem. Phys. Lett micro- scope tip and a silicon wafer. They deduced the pressure of liquid water inside the capillary

Balibar, Sébastien

426

Capillary Electrophoresis of DNA in Uncrosslinked Polymer Solutions  

E-print Network

Capillary Electrophoresis of DNA in Uncrosslinked Polymer Solutions: Evidence for a New Mechanism fused silica capillary filled with an uncrosslinked polymer solution. An early assumption.0-23.1 kbp) can be separated by CE in extremely dilute polymer solutions, which contain as little as 6 parts

Barron, Annelise E.

427

A Simple Double-Source Model for Interference of Capillaries  

ERIC Educational Resources Information Center

A simple but physically intuitive double-source model is proposed to explain the interferogram of a laser-capillary system, where two effective virtual sources are used to describe the rays reflected by and transmitted through the capillary. The locations of the two virtual sources are functions of the observing positions on the target screen. An…

Hou, Zhibo; Zhao, Xiaohong; Xiao, Jinghua

2012-01-01

428

THE IMPACT OF UNCERTAIN CENTRIFUGE CAPILLARY PRESSURE ON RESERVOIR SIMULATION  

E-print Network

THE IMPACT OF UNCERTAIN CENTRIFUGE CAPILLARY PRESSURE ON RESERVOIR SIMULATION SAM SUBBEY, MIKE estimation of hydrocarbon reserves. The centrifuge procedure provides laboratory data, which can be inverted are uncertain. This paper shows how the uncertainty in centrifuge capillary pressure can be quantified. It also

Sambridge, Malcolm

429

An investigation of capillary vibration during wire bonding process  

Microsoft Academic Search

As the bond pitch size decreases, understanding the behaviour of the capillary tube and monitoring bond quality becomes increasingly important. This paper uses finite element analysis (FEA) and laser Doppler interferometer to study the vibration of the capillary tube during the wire bonding process. Using a laser Doppler interferometer, the vibrations were measured along the x, y and z axis

Jian Gao; Robert Kelly; Zhijun Yang; Xin Chen

2008-01-01

430

Relative Permeability Analysis of Tube Bundle Models, Including Capillary Pressure  

Microsoft Academic Search

The analytical equations for calculating two-phase flow, including local capillary pressures, are developed for the bundle of parallel capillary tubes model. The flow equations that are derived were used to calculate dynamic immiscible displacements of oil by water under the constraint of a constant overall pressure drop across the tube bundle. Expressions for averaged fluid pressure gradients and total flow

J. T. Bartley; D. W. Ruth

2001-01-01

431

Large scale patterning of hydrogel microarrays using capillary pinning.  

PubMed

Capillary barriers provide a simple and elegant means for autonomous fluid-flow control in microfluidic systems. In this work, we report on the fabrication of periodic hydrogel microarrays in closed microfluidic systems using non-fluorescent capillary barriers. This design strategy enables the fabrication of picoliter-volume patterns of photopolymerized and thermo-gelling hydrogels without any defects and distortions. PMID:25512130

Gumuscu, Burcu; Bomer, Johan G; van den Berg, Albert; Eijkel, Jan C T

2015-01-22

432

Noninvasive Visualization and Analysis of Parafoveal Capillaries in Humans  

PubMed Central

Purpose. To demonstrate a noninvasive method to visualize and analyze the parafoveal capillary network in humans. Methods. An adaptive optics scanning laser ophthalmoscope was used to acquire high resolution retinal videos on human subjects. Video processing tools that enhance motion contrast were developed and applied to the videos to generate montages of parafoveal retinal capillaries. The capillary network and foveal avascular zone (FAZ) were extracted using video and image analysis algorithms. The capillary densities in the zone immediately outside the FAZ were calculated and the variation in density as a function of direction was investigated. Extracted FAZ geometries were used to calculate area and effective diameters. The authors also compared their method against fluorescein angiography (FA) for one subject. Results. The parafoveal capillaries were clearly visible when the motion contrast in noninvasive videos was enhanced. There was a marked improvement in the contrast of the parafoveal capillaries when compared to the unprocessed videos. The average FAZ area was 0.323 mm2, with an average effective diameter of 633 ?m. There was no variation in capillary density near the FAZ in different directions. Conclusions. Using motion cues to enhance vessel contrast is a powerful tool for visualizing the capillary network, in the absence of contrast agents. The authors demonstrate a tool to study the microcirculation of healthy subjects noninvasively. PMID:19907024

Martin, Joy A.; Roorda, Austin

2010-01-01

433

Capillary electrokinetic separations: Influence of mobile phase composition on performance  

SciTech Connect

The composition of the mobile phase employed in capillary zone electrophoresis and the related technique, micellar electrokinetic capillary chromatography, is an important factor in determining separation performance. The influences of ionic salt, surfactant, and organic solvent mobile phase additives on separation efficiency, retention, and elution range are discussed and demonstrated. 23 refs., 2 figs., 2 tabs.

Sepaniak, M.J.; Swaile, D.F.; Powell, A.C.; Cole, R.O.

1990-01-01

434

Gravitational capillary viscometer for low-temperature liquids  

Microsoft Academic Search

A pressurized gravitational capillary viscometer was developed for subcooled liquefied gases such as oxygen, nitrogen, hydrogen, and methane. It acquires accurate absolute viscosity measurements with an uncertainty of 1% at a 95.5% confidence level, necessary for the demands of aerospace engineering. The viscometer includes a coiled capillary of electroformed nickel that hydraulically connects two reservoirs located at equal heights. Using

David K. Hilton; Steven W. Van Sciver

2007-01-01

435

Brain capillary lesions produced by cocaine in rats.  

PubMed

In the last 20 years, acute and chronic cocaine addiction has increased among young and adult people. The effects of cocaine on brain vasculature of young animals have not been histologically studied in depth. In the present study, we report the lesions of brain capillaries, including the choroid plexus, produced by chronic cocaine administration, in adult Wistar rats receiving i.p., 30 mg/kg/day of aqueous cocaine hydrochloride solution. Rats were sacrificed after several days of treatment. Histopathological examination of capillaries from different brain regions and cerebellum was performed using light microscopy. At 7 days, there were initial signs of dilatation, rupture and thrombosis of capillaries. At 15 days of treatment small interstitial oedema and hemorrhages by rupture of the basal membrane of the capillaries was found. At 30 days of treatment, many capillaries from different areas showed fibroid endothelial thickening, and wall fibrosis become evident after 60 days of daily cocaine. In numerous places (cortex, gray nucleus: thalamus, caudate, hippocampus and cerebellum) we observed capillaries with an occluded lumen probably due to fibrosis or thrombi after 90 days of treatment. In the latter treatment, capillaries from the choroid plexuses had their lumen dilated and the epithelial cells vacuolated or necrotic. We hypothesize that the chronic administration of cocaine in rats induced brain lesio