WorldWideScience

Sample records for model hydrophilic surface

  1. Interaction mechanism between hydrophobic and hydrophilic surfaces: using polystyrene and mica as a model system.

    Science.gov (United States)

    Faghihnejad, Ali; Zeng, Hongbo

    2013-10-08

    The interactions between hydrophobic and hydrophilic molecules, particles, or surfaces occur in many biological phenomena and industrial processes. In this work, polystyrene (PS) and mica were chosen as a model system to investigate the interaction mechanism between hydrophilic and hydrophobic surfaces. Using a surface forces apparatus (SFA) coupled with a top-view optical microscope, interaction forces between PS and mica surfaces were directly probed in five different electrolyte solutions (i.e., NaCl, CaCl2, NaOH, HCl, and CH3COOH) of various concentrations. Long-range repulsion was observed in low electrolyte concentration (e.g., 0.001 M) which was mainly due to the presence of microscopic and submicroscopic bubbles on PS surface. A modified Derjaguin-Landau-Verwey-Overbeek (DLVO) theory well fits the interaction forces by taking into account the effect of bubbles on PS surface. The range of the repulsion was dramatically reduced in 1.0 M solutions of NaCl, CaCl2, and NaOH but did not significantly change in 1.0 M HCl and CH3COOH, which was due to ion specificity effect on the formation and stability of bubbles on PS surface. The range of repulsion was also significantly reduced to forces dominate the interaction between hydrophilic surface (i.e., mica) and hydrophobic polymer (i.e., PS), while the types of electrolytes (ion specificity), electrolyte concentration, degassing, and surface hydrophobicity can significantly affect the formation and stability of bubbles on the interacting surfaces, thus affecting the range and magnitude of the interaction forces.

  2. Wetting failure of hydrophilic surfaces promoted by surface roughness

    Science.gov (United States)

    Zhao, Meng-Hua; Chen, Xiao-Peng; Wang, Qing

    2014-06-01

    Wetting failure is of vital importance to many physical phenomena, such as industrial coating and drop emission. Here we show when and how the surface roughness promotes the destabilization of a moving contact line on a hydrophilic surface. Beyond the balance of the driving force and viscous resistance where a stable wetting interface is sustained, wetting failure occurs and is modified by the roughness of the surface. The promoting effect arises only when the wetting velocity is high enough to create a gas-liquid-solid composite interface in the vicinity of the moving contact line, and it is a function of the intrinsic contact angle and proportion of solid tops. We propose a model to explain splashes of rough solid spheres impacting into liquids. It reveals a novel concept that dynamic wetting on hydrophilic rough surfaces can be similar to that on hydrophobic surfaces, and brings a new way to design surfaces with specific wetting properties.

  3. Switchable Hydrophobic-Hydrophilic Surfaces

    CERN Document Server

    Bunker, B C; Huber, D L; Kent, M S; Kushmerick, J G; Lopez, G P; Manginell, R P; Méndez, S E; Yim, H

    2002-01-01

    Tethered films of poly n-isopropylacrylamide (PNIPAM) films have been developed as materials that can be used to switch the chemistry of a surface in response to thermal activation. In water, PNIPAM exhibits a thermally-activated phase transition that is accompanied by significant changes in polymer volume, water contact angle, and protein adsorption characteristics. New synthesis routes have been developed to prepare PNIPAM films via in-situ polymerization on self-assembled monolayers. Swelling transitions in tethered films have been characterized using a wide range of techniques including surface plasmon resonance, attenuated total reflectance infrared spectroscopy, interfacial force microscopy, neutron reflectivity, and theoretical modeling. PNIPAM films have been deployed in integrated microfluidic systems. Switchable PNIPAM films have been investigated for a range of fluidic applications including fluid pumping via surface energy switching and switchable protein traps for pre-concentrating and separating...

  4. Wetting of soap bubbles on hydrophilic, hydrophobic and superhydrophobic surfaces

    CERN Document Server

    Arscott, Steve

    2013-01-01

    Wetting of sessile bubbles on solid and liquid surfaces has been studied. A model is presented for the contact angle of a sessile bubble based on a modified Young equation - the experimental results agree with the model. A hydrophilic surface results in a bubble contact angle of 90 deg whereas on a superhydrophobic surface one observes 134 deg. For hydrophilic surfaces, the bubble angle diminishes with bubble radius - whereas on a superhydrophobic surface, the bubble angle increases. The size of the Plateau borders governs the bubble contact angle - depending on the wetting of the surface.

  5. Anionic and cationic Hofmeister effects on hydrophobic and hydrophilic surfaces.

    Science.gov (United States)

    Schwierz, Nadine; Horinek, Dominik; Netz, Roland R

    2013-02-26

    Using a two-step modeling approach, we address the full spectrum of direct, reversed, and altered ionic sequences as the charge of the ion, the charge of the surface, and the surface polarity are varied. From solvent-explicit molecular dynamics simulations, we extract single-ion surface interaction potentials for halide and alkali ions at hydrophilic and hydrophobic surfaces. These are used within Poisson-Boltzmann theory to calculate ion density and electrostatic potential distributions at mixed polar/unpolar surfaces for varying surface charge. The resulting interfacial tension increments agree quantitatively with experimental data and capture the Hofmeister series, especially the anomaly of lithium, which is difficult to obtain using continuum theory. Phase diagrams that feature different Hofmeister series as a function of surface charge, salt concentration, and surface polarity are constructed from the long-range force between two surfaces interacting across electrolyte solutions. Large anions such as iodide have a high hydrophobic surface affinity and increase the effective charge magnitude on negatively charged unpolar surfaces. Large cations such as cesium also have a large hydrophobic surface affinity and thereby compensate an external negative charge surface charge most efficiently, which explains the well-known asymmetry between cations and anions. On the hydrophilic surface, the size-dependence of the ion surface affinity is reversed, explaining the Hofmeister series reversal when comparing hydrophobic with hydrophilic surfaces.

  6. Wetting transitions on textured hydrophilic surfaces

    Science.gov (United States)

    Ishino, C.; Okumura, K.

    2008-04-01

    We consider the quasi-static energy of a drop on a textured hydrophilic surface, with taking the contact angle hysteresis (CAH) into account. We demonstrate how energy varies as the contact state changes from the Cassie state (in which air is trapped at the drop bottom) to the Wenzel state (in which liquid fills the texture at the drop bottom) assuming that the latter state nucleates from the center of the drop bottom. When the textured substrate is hydrophilic enough to allow spontaneous penetration of liquid film of the texture thickness, the present theory asserts that the drop develops into an experimentally observed state in which a drop looks like an egg fried without flipped over (sunny-side up) with a well-defined radius of “the egg yolk.” Otherwise, the final contact state of the drop becomes like a Wenzel state, but with the contact circle smaller than the original Wenzel state due to the CAH. We provide simple analytical estimations for the yolk radius of the “sunny-side-up” state and for the final radius of the contact circle of the pseudo-Wenzel state.

  7. Fluctuations of water near extended hydrophobic and hydrophilic surfaces

    OpenAIRE

    Patel, Amish J.; Chandler, David

    2009-01-01

    We use molecular dynamics simulations of the SPC-E model of liquid water to derive probability distributions for water density fluctuations in probe volumes of different shapes and sizes, both in the bulk as well as near hydrophobic and hydrophilic surfaces. To obtain our results, we introduce a biased sampling of coarse-grained densities, which in turn biases the actual solvent density. The technique is easily combined with molecular dynamics integration algorithms. Our principal result is t...

  8. A hydrophilic dental implant surface exhibits thrombogenic properties in vitro.

    Science.gov (United States)

    Hong, Jaan; Kurt, Seta; Thor, Andreas

    2013-02-01

    Surface modifications of dental implants have gained attention during several years and the thrombotic response from blood components with these materials has become more important during recent years. The aims of this study were to evaluate the thrombogenic response of whole blood, in contact with clinically used dental surfaces, Sandblasted Large grit Acid etched titanium (SLA) and Sandblasted Large grit Acid etched, and chemically modified titanium with hydrophilic properties (SLActive). An in vitro slide chamber model, furnished with heparin, was used in which whole blood came in contact with slides of the test surfaces. After incubation (60-minute rotation at 22 rpm in a 37°C water bath), blood was mixed with ethylenediaminetetraacetic acid (EDTA) or citrate, further centrifuged at +4°C. Finally, plasma was collected pending analysis. Whole blood in contact with surfaces resulted in significantly higher binding of platelets to the hydrophilic surface, accompanied by a significant increase of contact activation of the coagulation cascade. In addition, the platelet activation showed a similar pattern with a significant elevated release of β-TG from platelet granule. The conclusion that can be drawn from the results in our study is that the hydrophilic modification seems to augment the thrombogenic properties of titanium with implications for healing into bone of, that is titanium dental implants. © 2011 Wiley Periodicals, Inc.

  9. Understanding the drop impact on moving hydrophilic and hydrophobic surfaces.

    Science.gov (United States)

    Almohammadi, H; Amirfazli, A

    2017-03-08

    In this paper, a systematic study was performed to understand the drop impact on hydrophilic and hydrophobic surfaces that were moving in the horizontal direction. Drops (D0 = 2.5 mm) of liquids with three different viscosities were used. Wide ranges of drop normal velocity (0.5 to 3.4 m s(-1)) and surface velocity (0 to 17 m s(-1)) were studied. High speed imaging from the top and side was used to capture the impact phenomena. It was found that drop impact behavior on a moving surface significantly differs from that on a stationary surface at both the lamella extension stage (i.e. t ≤ tmax) and the retraction stage (t > tmax). Starting with the lamella extension stage, it was observed that the drop spreads asymmetrically over a moving surface. It was also found that the splashing behavior of the drop upon impact on a moving surface, unlike the understanding in the literature, is azimuthally different along the lamella contact line. In the case of the drop spreading over a moving surface, the surface movement stretches the expanded lamella in the direction of the surface motion. For hydrophilic surfaces, the stretched lamella pins to the surface and moves with the surface velocity; however, for hydrophobic surfaces, the lamella recoils during such stretching. A new model was developed to determine the splashing threshold of the drop impact on a moving surface. The model is capable of describing the azimuthally different behavior of the splashing which is a function of normal capillary and Weber numbers, surface velocity, and surface wettability. It was also found that the increase of the viscosity decreases the splashing threshold. Finally, comprehensive regime maps of the drop impact outcome on a moving surface were provided for both t ≤ tmax and t > tmax stages.

  10. Hydrophilic-oleophobic stimuli-responsive materials and surfaces

    Science.gov (United States)

    Howarter, John A.

    Due to their high surface energy, hydrophilic surfaces are susceptible to contamination which is difficult to remove and often ruins the surface. Hydrophilic-oleophobic coatings have a diverse engineering potential including applications as self-cleaning surfaces, extended life anti-fog coatings, and environmental remediation in the selective filtration of oil-in-water mixtures. A successful design model for hydrophilic-oleophobic behavior has been developed using perfluorinated surfactants covalently bound to a surface. Within this design model, a variety of materials have been explored which the surfactants are covalently bound to a substrate; similarly, the surfactants may also be incorporated as a monomer into bulk copolymers. Surfactant based surfaces exhibited simultaneous hydrophilicity, necessary for anti-fogging, and oleophobicity, necessary for contamination resistance. The combination of these features rendered the surface as self-cleaning. Surfactant based brushes, composed of polyethylene glycol and perfluorinated constituents were grafted on to silica surfaces. The relationship between brush density and stimuli-responsiveness was determined by varying grafting conditions. The resultant surfaces were characterized with respect to chemical composition, brush thickness, and wetting behavior of water and hexadecane. Optimized surfaces exhibited stimuli-responsive behavior such that the surfaces will be wetted by water but not by oil. Surfactants were incorporated into random copolymers to create self-cleaning polymers which could be easily coated on to surfaces post-synthesis. Acrylic acid, methyl methacrylate, and hydroxyethyl methacrylate were used as comonomers; feed ratio was varied to establish compositional limits of stimuli-responsive behavior. Polymer composition dictated coating durability and self-cleaning performance as determined by water and hexadecane contact angle. The ability of select coatings to mitigate fogging was assessed in two

  11. Frictional forces between hydrophilic and hydrophobic particle coated nanostructured surfaces

    DEFF Research Database (Denmark)

    Hansson, Petra M; Claesson, Per M.; Swerin, Agne;

    2013-01-01

    by utilizing the atomic force microscope (AFM). The chemistry of the surfaces and the probe was varied between hydrophilic silica and hydrophobized silica. For hydrophilic silica surfaces, the friction coefficient was significantly higher for the particle coated surfaces than on the flat reference surface. All...... the particle coated surfaces exhibited similar friction coefficients, from which it may be concluded that the surface geometry, and not the roughness amplitude per se, influenced the measured friction. During measurements with hydrophobic surfaces, strong adhesive forces related to the formation of a bridging...... air cavity were evident from both normal force and friction force measurements. In contrast to the frictional forces between the hydrophilic surfaces, the friction coefficient for hydrophobic surfaces was found to depend on the surface structure and we believe that this dependence is related...

  12. Mechanism of Hydrophilicity by Radiation-Induced Surface Activation

    Science.gov (United States)

    Honjo, Yoshio; Furuya, Masahiro; Takamasa, Tomoji; Okamoto, Koji

    When a metal oxide is irradiated by gamma rays, the irradiated surface becomes hydrophilic. This surface phenomenon is called as radiation-induced surface activation (RISA) hydrophilicity. In order to investigate gamma ray-induced and photoinduced hydrophilicity, the contact angles of water droplets on a titanium dioxide surface were measured in terms of irradiation intensity and time for gamma rays of cobalt-60 and for ultraviolet rays. Reciprocals of the contact angles increased in proportion to the irradiation time before the contact angles reached its super-hydrophilic state. The irradiation time dependency is equal to each other qualitatively. In addition, an effect of ambient gas was investigated. In pure argon gas, the contact angle remains the same against the irradiation time. This clearly indicates that certain humidity is required in ambient gas to take place of RISA hydrophilicity. A single crystal titanium dioxide (100) surface was analyzed by X-ray photoelectron spectrometry (XPS). After irradiation with gamma rays, a peak was found in the O1s spectrum, which indicates the adsorption of dissociative water to a surface 5-fold coordinate titanium site, and the formation of a surface hydroxyl group. We conclude that the RISA hydrophilicity is caused by chemisorption of the hydroxyl group on the surface.

  13. Tuning surface hydrophilicity/hydrophobicity of hydrocarbon proton exchange membranes (PEMs).

    Science.gov (United States)

    He, Chenfeng; Mighri, Frej; Guiver, Michael D; Kaliaguine, Serge

    2016-03-15

    The effect of annealing on the surface hydrophilicity of various representative classes of hydrocarbon-based proton exchange membranes (PEMs) is investigated. In all cases, a more hydrophilic membrane surface develops after annealing at elevated temperatures. The annealing time also had some influence, but in different ways depending on the class of PEM. Longer annealing times resulted in more hydrophilic membrane surfaces for copolymerized sulfonated poly(ether ether ketone) (SPEEK-HQ), while the opposite behavior occurred in sulfonated poly(aryl ether ether ketone) (Ph-SPEEK), sulfonated poly(aryl ether ether ketone ketone) (Ph-m-SPEEKK) and sulfonated poly (aryl ether ether nitrile) (SPAEEN-B). Increased surface hydrophilicity upon annealing results from ionic cluster decomposition, according to the "Eisenberg-Hird-Moore model" (EHM). The increased surface hydrophilicity is supported by contact angle (CA) measurements, and the cluster decomposition is auxiliarily supported by probing the level of atomic sulfur (sulfonic acid) within different surface depths using angle-dependent XPS as well as ATR-FTIR. Membrane acidification leads to more hydrophilic surfaces by elimination of the hydrogen bonding that occurs between strongly-bound residual solvent (dimethylacetamide, DMAc) and PEM sulfonic acid groups. The study of physicochemical tuning of surface hydrophilicity/hydrophobicity of PEMs by annealing and acidification provides insights for improving membrane electrode assembly (MEA) fabrication in fuel cell (FC).

  14. Study on hydrophilicity of polymer surfaces improved by plasma treatment

    Science.gov (United States)

    Lai, Jiangnan; Sunderland, Bob; Xue, Jianming; Yan, Sha; Zhao, Weijiang; Folkard, Melvyn; Michael, Barry D.; Wang, Yugang

    2006-03-01

    Surface properties of polycarbonate (PC), polypropylene (PP), polyethylene terephthalate (PET) samples treated by microwave-induced argon plasma have been studied with contact angle measurement, X-ray photoelectron spectroscopy (XPS) and scanned electron microscopy (SEM). It is found that plasma treatment modified the surfaces both in composition and roughness. Modification of composition makes polymer surfaces tend to be highly hydrophilic, which mainly depended on the increase of ratio of oxygen-containing group as same as other papers reported. And this experiment further revealed that C dbnd O bond is the key factor to the improvement of the hydrophilicity of polymer surfaces. Our SEM observation on PET shown that the roughness of the surface has also been improved in micron scale and it has influence on the surface hydrophilicity.

  15. Study on hydrophilicity of polymer surfaces improved by plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Lai Jiangnan [Key Laboratory of Heavy Ion Physics, Peking University, MOE, Beijing (China); Sunderland, Bob [Gray Cancer Institute, Mount Vernon Hospital, Northwood, Middlesex (United Kingdom); Xue Jianming [Key Laboratory of Heavy Ion Physics, Peking University, MOE, Beijing (China); Yan, Sha [Key Laboratory of Heavy Ion Physics, Peking University, MOE, Beijing (China); Zhao Weijiang [Key Laboratory of Heavy Ion Physics, Peking University, MOE, Beijing (China); Folkard, Melvyn [Gray Cancer Institute, Mount Vernon Hospital, Northwood, Middlesex (United Kingdom); Michael, Barry D. [Gray Cancer Institute, Mount Vernon Hospital, Northwood, Middlesex (United Kingdom); Wang Yugang [Key Laboratory of Heavy Ion Physics, Peking University, MOE, Beijing (China)]. E-mail: ygwang@pku.edu.cn

    2006-03-15

    Surface properties of polycarbonate (PC), polypropylene (PP), polyethylene terephthalate (PET) samples treated by microwave-induced argon plasma have been studied with contact angle measurement, X-ray photoelectron spectroscopy (XPS) and scanned electron microscopy (SEM). It is found that plasma treatment modified the surfaces both in composition and roughness. Modification of composition makes polymer surfaces tend to be highly hydrophilic, which mainly depended on the increase of ratio of oxygen-containing group as same as other papers reported. And this experiment further revealed that C=O bond is Key factor to the improvement of the hydrophilicity of polymer surfaces. Our SEM observation on PET shown that the roughness of the surface has also been improved in micron scale and it has influence on the surface hydrophilicity.

  16. Hydroglyphics: Demonstration of Selective Wetting on Hydrophilic and Hydrophobic Surfaces

    Science.gov (United States)

    Kim, Philseok; Alvarenga, Jack; Aizenberg, Joanna; Sleeper, Raymond S.

    2013-01-01

    A visual demonstration of the difference between hydrophilic and hydrophobic surfaces has been developed. It involves placing a shadow mask on an optically clear hydrophobic plastic dish, corona treating the surface with a modified Tesla coil, removing the shadow mask, and visualizing the otherwise invisible message or pattern by applying water,…

  17. Fabrication of zero contact angle ultra-super hydrophilic surfaces.

    Science.gov (United States)

    Jothi Prakash, C G; Clement Raj, C; Prasanth, R

    2017-01-05

    Zero contact angle surfaces have been created with the combined effect of nanostructure and UV illumination. The contact angle of titanium surface has been optimized to 3.25°±1°. with nanotubular structures through electrochemical surface modification. The porosity and surface energy of tubular TiO2 layer play critical role over the surface wettability and the hydrophilicity of the surface. The surface free energy has been enhanced from 23.72mJ/m(2) (bare titanium surface) to 87.11mJ/m(2) (nanotubular surface). Similar surface with TiO2 nanoparticles coating shows superhydrophilicity with contact angle up to 5.63°±0.95°. This implies liquid imbibition and surface curvature play a crucial role in surface hydrophilicity. The contact angle has been further reduced to 0°±0.86° by illuminating the surface with UV radiation. Results shows that by tuning the nanotube morphology, highly porous surfaces can be fabricated to reduce contact angle and enhance wettability. This study provides an insight into the inter-relationship between surface structural factors and ultra-superhydrophilic surfaces which can help to optimize thermal hydraulic and self cleaning surfaces.

  18. Quantitative and qualitative evaluation of adsorption/desorption of bovine serum albumin on hydrophilic and hydrophobic surfaces.

    Science.gov (United States)

    Jeyachandran, Y L; Mielczarski, E; Rai, B; Mielczarski, J A

    2009-10-06

    We studied the adsorption of bovine serum albumin (BSA) from phosphate-buffered saline (pH 7.4) to hydrophilic and hydrophobic surfaces. Attenuated total reflection Fourier transform infrared spectroscopy, supported by spectral simulation, allowed us to determine with high precision the amount of BSA adsorbed (surface coverage) and its structural composition. The adsorbed BSA molecules had an alpha-helical structure on both hydrophobic and hydrophilic surfaces but had different molecular conformations and adsorption strengths on the two types of surface. Adsorption of BSA was saturated at around 50% surface coverage on the hydrophobic surface, whereas on the hydrophilic surface the adsorption reached 95%. The BSA molecules adsorbed to the hydrophilic surface with a higher interaction strength than to the hydrophobic surface. Very little adsorbed BSA could be desorbed from the hydrophilic surface, even using 0.1 M sodium dodecyl sulfate, a strong detergent solution. The formation of BSA-phosphate surface complexes was observed under different BSA adsorption conditions on hydrophobic and hydrophilic surfaces. The formation of these complexes correlated with the more efficient blocking of nonspecific interactions by the adsorbed BSA layer. Results from the molecular modeling of BSA interactions with hydrophobic and hydrophilic surfaces support the spectroscopic findings.

  19. Staphylococcus epidermidis adhesion on hydrophobic and hydrophilic textured biomaterial surfaces.

    Science.gov (United States)

    Xu, Li-Chong; Siedlecki, Christopher A

    2014-06-01

    It is of great interest to use nano- or micro-structured surfaces to inhibit microbial adhesion and biofilm formation and thereby to prevent biomaterial-associated infection, without modification of the surface chemistry or bulk properties of the materials and without use of the drugs. Our previous study showed that a submicron textured polyurethane surface can inhibit staphylococcal bacterial adhesion and biofilm formation. To further understand the effect of the geometry of textures on bacterial adhesion as well as the underlying mechanism, in this study, submicron and micron textured polyurethane surfaces featuring ordered arrays of pillars were fabricated and modified to have different wettabilities. All the textured surfaces were originally hydrophobic and showed significant reductions in Staphylococcus epidermidis RP62A adhesion in phosphate buffered saline or 25% platelet poor plasma solutions under shear, as compared to smooth surfaces. After being subjected to an air glow discharge plasma treatment, all polyurethane surfaces were modified to hydrophilic, and reductions in bacterial adhesion on surfaces were subsequently found to be dependent on the size of the patterns. The submicron patterned surfaces reduced bacterial adhesion, while the micron patterned surfaces led to increased bacterial adhesion. The extracellular polymeric substances (EPS) from the S. epidermidis cell surfaces were extracted and purified, and were coated on a glass colloidal surface so that the adhesion force and separation energy in interactions of the EPS and the surface could be measured by colloidal probe atomic force microscopy. These results were consistent with the bacterial adhesion observations. Overall, the data suggest that the increased surface hydrophobicity and the decreased availability of the contact area contributes to a reduction in bacterial adhesion to the hydrophobic textured surfaces, while the availability of the contact area is the primary determinant factor

  20. Design and Fabrication of a Hybrid Superhydrophobic-Hydrophilic Surface That Exhibits Stable Dropwise Condensation.

    Science.gov (United States)

    Mondal, Bikash; Mac Giolla Eain, Marc; Xu, QianFeng; Egan, Vanessa M; Punch, Jeff; Lyons, Alan M

    2015-10-28

    Condensation of water vapor is an essential process in power generation, water collection, and thermal management. Dropwise condensation, where condensed droplets are removed from the surface before coalescing into a film, has been shown to increase the heat transfer efficiency and water collection ability of many surfaces. Numerous efforts have been made to create surfaces which can promote dropwise condensation, including superhydrophobic surfaces on which water droplets are highly mobile. However, the challenge with using such surfaces in condensing environments is that hydrophobic coatings can degrade and/or water droplets on superhydrophobic surfaces transition from the mobile Cassie to the wetted Wenzel state over time and condensation shifts to a less-effective filmwise mechanism. To meet the need for a heat-transfer surface that can maintain stable dropwise condensation, we designed and fabricated a hybrid superhydrophobic-hydrophilic surface. An array of hydrophilic needles, thermally connected to a heat sink, was forced through a robust superhydrophobic polymer film. Condensation occurs preferentially on the needle surface due to differences in wettability and temperature. As the droplet grows, the liquid drop on the needle remains in the Cassie state and does not wet the underlying superhydrophobic surface. The water collection rate on this surface was studied using different surface tilt angles, needle array pitch values, and needle heights. Water condensation rates on the hybrid surface were shown to be 4 times greater than for a planar copper surface and twice as large for silanized silicon or superhydrophobic surfaces without hydrophilic features. A convection-conduction heat transfer model was developed; predicted water condensation rates were in good agreement with experimental observations. This type of hybrid superhydrophobic-hydrophilic surface with a larger array of needles is low-cost, robust, and scalable and so could be used for heat

  1. Influence of roughness on capillary forces between hydrophilic surfaces

    Science.gov (United States)

    van Zwol, P. J.; Palasantzas, G.; de Hosson, J. Th. M.

    2008-09-01

    Capillary forces have been measured by atomic force microscopy in the plate-sphere setup between gold, borosilicate glass, GeSbTe, titanium, and UV-irradiated amorphous titanium-dioxide surfaces. The force measurements were performed as a function contact time and surface roughness in the range 0.2-15nm rms and relative humidity ranging between 2% and 40%. It is found that even for the lowest attainable relative humidity (˜2%±1%) very large capillary forces are still present. The latter suggests the persistence of a nanometers-thick adsorbed water layer that acts as a capillary bridge between contacting surfaces. Moreover, we found a significantly different scaling behavior of the force with rms roughness for materials with different hydrophilicity as compared to gold-gold surfaces.

  2. Effect of shape of protrusions and roughness on the hydrophilicity of a surface

    Science.gov (United States)

    Chowdhury, Sheelan Sengupta; Pandey, Prithvi Raj; Kumar, Rajnish; Roy, Sudip

    2017-10-01

    We have investigated wetting of model rough surfaces made up of hydrophilic triangular and hexagonal pillars (protrusions). The surface roughnesses are altered by varying the area of the rough surface, the height of the pillars, and the surface interactions to the water. We have established a correlation between structure i.e., the shape of a pillar, which actually depends on the number of edges (due to shape), and the wetting phenomena. We have found that surface with higher number of edges repels water at lower roughness value. We explain the correlation by analyzing the variation of interactions energy components and density profiles of water on the structured surfaces.

  3. Do surfaces with mixed hydrophilic and hydrophobic areas enhance pool boiling?

    CERN Document Server

    Betz, Amy; Qiu, Huihe; Attinger, Daniel

    2010-01-01

    We demonstrate that smooth and flat surfaces combining hydrophilic and hydrophobic patterns improve pool boiling performance. Compared to a hydrophilic surface with 7^\\circ wetting angle, the measured critical heat flux and heat transfer coefficients of the enhanced surfaces are up to respectively 65 and 100% higher. Different networks combining hydrophilic and hydrophobic regions are characterized. While all tested networks enhance the heat transfer coefficient, large enhancements of critical heat flux are typically found for hydrophilic networks featuring hydrophobic islands. Hydrophilic networks indeed are shown to prevent the formation of an insulating vapor layer.

  4. Free surface entropic lattice Boltzmann simulations of film condensation on vertical hydrophilic plates

    DEFF Research Database (Denmark)

    Hygum, Morten Arnfeldt; Karlin, Iliya; Popok, Vladimir

    2015-01-01

    A model for vapor condensation on vertical hydrophilic surfaces is developed using the entropic lattice Boltzmann method extended with a free surface formulation of the evaporation–condensation problem. The model is validated with the steady liquid film formation on a flat vertical wall....... It is shown that the model is in a good agreement with the classical Nusselt equations for the laminar flow regime. Comparisons of the present model with other empirical models also demonstrate good agreement beyond the laminar regime. This allows the film condensation modeling at high film Reynolds numbers...

  5. Improvement of PET surface hydrophilicity and roughness through blending

    Energy Technology Data Exchange (ETDEWEB)

    Kolahchi, Ahmad Rezaei; Ajji, Abdellah; Carreau, Pierre J. [CREPEC, Chemical Engineering Department, Polytechnique Montreal, 2500 chemin de Polytechnique, Quebec, Montreal (Canada)

    2015-05-22

    Controlling the adhesion of the polymer surface is a key issue in surface science, since polymers have been a commonly used material for many years. The surface modification in this study includes two different aspects. One is to enhance the hydrophilicity and the other is to create the roughness on the PET film surface. In this study we developed a novel and simple approach to modify polyethylene terephthalate (PET) film surface through polymer blending in twin-screw extruder. One example described in the study uses polyethylene glycol (PEG) in polyethylene terephthalate (PET) host to modify a PET film surface. Low content of polystyrene (PS) as a third component was used in the system to increase the rate of migration of PEG to the surface of the film. Surface enrichment of PEG was observed at the polymer/air interface of the polymer film containing PET-PEG-PS whereas for the PET-PEG binary blend more PEG was distributed within the bulk of the sample. Furthermore, a novel method to create roughness at the PET film surface was proposed. In order to roughen the surface of PET film, a small amount of PKHH phenoxy resin to change PS/PET interfacial tension was used. The compatibility effect of PKHH causes the formation of smaller PS droplets, which were able to migrate more easily through PET matrix. Consequently, resulting in a locally elevated concentration of PS near the surface of the film. The local concentration of PS eventually reached a level where a co-continuous morphology occurred, resulting in theinstabilities on the surface of the film.

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

    Science.gov (United States)

    Antonini, Carlo; Amirfazli, Alidad; Marengo, Marco

    2012-10-01

    Experiments to understand the effect of surface wettability on impact characteristics of water drops onto solid dry surfaces were conducted. Various surfaces were used to cover a wide range of contact angles (advancing contact angle from 48° to 166°, and contact angle hysteresis from 5° to 56°). Several different impact conditions were analyzed (12 impact velocities on 9 different surfaces, among which 2 were superhydrophobic). Results from impact tests with millimetric drops show that two different regimes can be identified: a moderate Weber number regime (30 200), 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.

  7. Transforming plastic surfaces with electrophilic backbones from hydrophobic to hydrophilic.

    Science.gov (United States)

    Kim, Samuel; Bowen, Raffick A R; Zare, Richard N

    2015-01-28

    We demonstrate a simple nonaqueous reaction scheme for transforming the surface of plastics from hydrophobic to hydrophilic. The chemical modification is achieved by base-catalyzed trans-esterification with polyols. It is permanent, does not release contaminants, and causes no optical or mechanical distortion of the plastic. We present contact angle measurements to show successful modification of several types of plastics including poly(ethylene terephthalate) (PET) and polycarbonate (PC). Its applicability to blood analysis is explored using chemically modified PET blood collection tubes and found to be quite satisfactory. We expect this approach will reduce the cost of manufacturing plastic devices with optimized wettability and can be generalized to other types of plastic materials having an electrophilic linkage as its backbone.

  8. Droplet Transport Mechanism on Horizontal Hydrophilic/Hydrophobic Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Myong, Hyon Kook [Kookmin University, Seoul (Korea, Republic of)

    2014-06-15

    A fluid transport technique is a key issue for the development of microfluidic systems. In this study, the movement of a droplet on horizontal hydrophilic/hydrophobic surfaces, which is a new concept to transport droplets without external power sources that was recently proposed by the author, was simulated using an in-house solution code(PowerCFD). This code employs an unstructured cell-centered method based on a conservative pressure-based finite-volume method with interface capturing method(CICSAM) in a volume of fluid(VOF) scheme for phase interface capturing. The droplet transport mechanism is examined through numerical results that include velocity vectors, pressure contours, and total kinetic energy inside and around the droplet.

  9. Heterogeneous ice nucleation controlled by the coupling of surface crystallinity and surface hydrophilicity

    CERN Document Server

    Bi, Yuanfei; Li, Tianshu

    2015-01-01

    The microscopic mechanisms controlling heterogeneous ice nucleation are complex and remain poorly understood. Although good ice nucleators are generally believed to match ice lattice and to bind water, counter examples are often identified. Here we show, by advanced molecular simulations, that the heterogeneous nucleation of ice on graphitic surface is controlled by the coupling of surface crystallinity and surface hydrophilicity. Molecular level analysis reveals that the crystalline graphitic lattice with an appropriate hydrophilicity may indeed template ice basal plane by forming a strained ice layer, thus significantly enhancing its ice nucleation efficiency. Remarkably, the templating effect is found to transit from within the first contact layer of water to the second as the hydrophilicity increases, yielding an oscillating distinction between the crystalline and amorphous graphitic surfaces in their ice nucleation efficiencies. Our study sheds new light on the long-standing question of what constitutes ...

  10. Forces involved in bacterial adhesion to hydrophilic and hydrophobic surfaces.

    Science.gov (United States)

    Boks, Niels P; Norde, Willem; van der Mei, Henny C; Busscher, Henk J

    2008-10-01

    Using a parallel-plate flow chamber, the hydrodynamic shear forces to prevent bacterial adhesion (F(prev)) and to detach adhering bacteria (F(det)) were evaluated for hydrophilic glass, hydrophobic, dimethyldichlorosilane (DDS)-coated glass and six different bacterial strains, in order to test the following three hypotheses. 1. A strong hydrodynamic shear force to prevent adhesion relates to a strong hydrodynamic shear force to detach an adhering organism. 2. A weak hydrodynamic shear force to detach adhering bacteria implies that more bacteria will be stimulated to detach by passing an air-liquid interface (an air bubble) through the flow chamber. 3. DLVO (Derjaguin, Landau, Verwey, Overbeek) interactions determine the characteristic hydrodynamic shear forces to prevent adhesion and to detach adhering micro-organisms as well as the detachment induced by a passing air-liquid interface. F(prev) varied from 0.03 to 0.70 pN, while F(det) varied from 0.31 to over 19.64 pN, suggesting that after initial contact, strengthening of the bond occurs. Generally, it was more difficult to detach bacteria from DDS-coated glass than from hydrophilic glass, which was confirmed by air bubble detachment studies. Calculated attractive forces based on the DLVO theory (F(DLVO)) towards the secondary interaction minimum were higher on glass than on DDS-coated glass. In general, all three hypotheses had to be rejected, showing that it is important to distinguish between forces acting parallel (hydrodynamic shear) and perpendicular (DLVO, air-liquid interface passages) to the substratum surface.

  11. Droplet nucleation on a well-defined hydrophilic-hydrophobic surface of 10 nm order resolution.

    Science.gov (United States)

    Yamada, Yutaka; Ikuta, Tatsuya; Nishiyama, Takashi; Takahashi, Koji; Takata, Yasuyuki

    2014-12-01

    Water condensation on a hybrid hydrophilic-hydrophobic surface was investigated to reveal nucleation mechanisms at the microscale. Focused ion beam (FIB) irradiation was used to change the wettability of the hydrophobic surface with 10 nm order spatial resolution. Condensation experiments were conducted using environmental scanning electron microscopy; droplets, with a minimum diameter of 800 nm, lined up on the FIB-irradiated hydrophilic lines. The heterogeneous nucleation theory was extended to consider the water molecules attracted to the hydrophilic area, thereby enabling explanation of the nucleation mechanism under unsaturated conditions. Our results showed that the effective surface coverage of the water molecules on the hydrophilic region was 0.1-1.1 at 0.0 °C and 560 Pa and was dependent on the width of the FIB-irradiated hydrophilic lines and hydrophobic area. The droplet nucleation mechanism unveiled in this work would enable the design of new surfaces with enhanced dropwise condensation heat transfer.

  12. Water-Mediated Interactions between Hydrophilic and Hydrophobic Surfaces.

    Science.gov (United States)

    Kanduč, Matej; Schlaich, Alexander; Schneck, Emanuel; Netz, Roland R

    2016-09-01

    All surfaces in water experience at short separations hydration repulsion or hydrophobic attraction, depending on the surface polarity. These interactions dominate the more long-ranged electrostatic and van der Waals interactions and are ubiquitous in biological and colloidal systems. Despite their importance in all scenarios where the surface separation is in the nanometer range, the origin of these hydration interactions is still unclear. Using atomistic solvent-explicit molecular dynamics simulations, we analyze the interaction free energies of charge-neutral model surfaces with different elastic and water-binding properties. The surface polarity is shown to be the most important parameter that not only determines the hydration properties and thereby the water contact angle of a single surface but also the surface-surface interaction and whether two surfaces attract or repel. Elastic properties of the surfaces are less important. On the basis of surface contact angles and surface-surface binding affinities, we construct a universal interaction diagram featuring three different interaction regimes-hydration repulsion, cavitation-induced attraction-and for intermediate surface polarities-dry adhesion. On the basis of scaling arguments and perturbation theory, we establish simple combination rules that predict the interaction behavior for combinations of dissimilar surfaces.

  13. PLASMA POLYMERIZATION OF HYDROPHILIC AND HYDROPHOBIC MONOMERS FOR SURFACE MODIFICATION OF NUCLE-MICROPOROUS MEMBRANE

    Institute of Scientific and Technical Information of China (English)

    LI Xuefen; LI Zhifen; CHEN Chuanfu; WU Wenhui

    1990-01-01

    Surface modification of nucle-microporous membrane by plasma polymerization of HEMA, NVP and D4 has been studied. The hydrophilicity of membranes was increased with increasing of plasma polymerization time of hydrophilic monomers HEMA and NVP. The flow rate of water through the membrane was increased remarkably after plasma polymerization of HEMA on it.

  14. Surface hydrophilicity of PLGA fibers governs in vitro mineralization and osteogenic differentiation

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Minnah; Arora, Aditya; Katti, Dhirendra S., E-mail: dsk@iitk.ac.in

    2014-12-01

    Interfacial properties of biomaterials play an important role in governing their interaction with biological microenvironments. This work investigates the role of surface hydrophilicity of electrospun poly(lactide-co-glycolide) (PLGA) fibers in determining their biological response. For this, PLGA is blended with varying amounts of Pluronic®F-108 and electrospun to fabricate microfibers with varying surface hydrophilicity. The results of mineralization study in simulated body fluid (SBF) demonstrate a significant enhancement in mineralization with an increase in surface hydrophilicity. While presence of serum proteins in SBF reduces absolute mineral content, mineralization continues to be higher on samples with higher surface hydrophilicity. The results from in vitro cell culture studies demonstrate a marked improvement in mesenchymal stem cell —adhesion, elongation, proliferation, infiltration, osteogenic differentiation and matrix mineralization on hydrophilized fibers. Therefore, hydrophilized PLGA fibers are advantageous both in terms of mineralization and elicitation of favorable cell response. Since most of the polymeric materials being used in orthopedics are hydrophobic in nature, the results from this study have strong implications in the future design of interfaces of such hydrophobic materials. In addition, the work proposes a facile method for the modification of electrospun fibers of hydrophobic polymers by blending with a poloxamer for improved bone tissue regeneration. - Highlights: • Surface hydrophilicity of PLGA modulated by blending with Pluronic F-108. • Hydrophilized fibers support better in vitro mineralization. • Mineralization trends retained in the presence of adsorbed serum proteins. • Hydrophilized fibers promote better cell adhesion and proliferation. • Hydrophilized fibers also enable better osteogenic differentiation.

  15. Experimental study on effect of surface vibration on micro textured surfaces with hydrophobic and hydrophilic materials

    Science.gov (United States)

    Yao, Chun-Wei; Lai, Chen-Ling; Alvarado, Jorge L.; Zhou, Jiang; Aung, Kendrick T.; Mejia, Jose E.

    2017-08-01

    Artificial hydrophobic surfaces have been studied in the last ten years in an effort to understand the effects of structured micro- and nano-scale features on droplet motion and self-cleaning mechanisms. Among these structured surfaces, micro-textured surfaces consisting of a combination of hydrophilic and hydrophobic materials have been designed, fabricated and characterized to understand how surface properties and morphology affect enhanced self-cleaning mechanisms. However, use of micro textured surfaces leads to a strong pinning effect that takes place between the droplets and the hydrophobic-hydrophilic edge, leading to a significant contact angle hysteresis effect. This research study focuses on the effects of surface vibrations on droplet shedding at different inclined angles on micro-textured surfaces. Surface vibration and shedding processes were experimentally characterized using a high speed imaging system. Experimental results show that droplets under the influence of surface vibration depict different contour morphologies when vibrating at different resonance frequencies. Moreover, droplet sliding angles can be reduced through surface vibration when the proper combination of droplet size and surface morphology is prescribed.

  16. Measurement of surface crystallinity of PAA and PAANa coatings and its effect on hydrophilicity of coatings

    Institute of Scientific and Technical Information of China (English)

    潘春跃; 刘清泉; 徐先华; 陈振华

    2003-01-01

    The solutions of poly(acrylic acid)(PAA), poly(acrylic acid sodium)(PAANa) were coated on aluminium fins by roll coating method. The coatings with different crystallinity were obtained by varying baking time and temperature. Their surface crystallinity and surface tension were measured, and their spreading speed constant and equilibrium contact angle were tested also. The correlation of surface crystallinity, surface tension, spreading speed constant and surface hydrophilicity was discussed. It is demonstrated that surface tension and spreading speed constant increase, while equilibrium contact angle declines with increasing surface crystallinity of coatings, that is to say, the hydrophilicity of coatings is improved with surface crystallinity of coatings increasing.

  17. Forces involved in bacterial adhesion to hydrophilic and hydrophobic surfaces

    NARCIS (Netherlands)

    Boks, N.P.; Norde, W.; Meil, H.C.; Busscher, H.J.

    2008-01-01

    Using a parallel-plate flow chamber, the hydrodynamic shear forces to prevent bacterial adhesion (F-prev) and to detach adhering bacteria (F-det) were evaluated for hydrophilic glass, hydrophobic, dimethyldichlorosilane (DDS)-coated glass and six different bacterial strains, in order to test the

  18. Forces involved in bacterial adhesion to hydrophilic and hydrophobic surfaces

    NARCIS (Netherlands)

    Boks, Niels P.; Norde, Willem; van der Mei, Henny C.; Busscher, Henk J.

    2008-01-01

    Using a parallel-plate flow chamber, the hydrodynamic shear forces to prevent bacterial adhesion (F(prev)) and to detach adhering bacteria (F(det)) were evaluated for hydrophilic glass, hydrophobic, dimethyldichlorosilane (DDS)-coated glass and six different bacterial strains, in order to test the

  19. Forces involved in bacterial adhesion to hydrophilic and hydrophobic surfaces

    NARCIS (Netherlands)

    Boks, N.P.; Norde, W.; Meil, H.C.; Busscher, H.J.

    2008-01-01

    Using a parallel-plate flow chamber, the hydrodynamic shear forces to prevent bacterial adhesion (F-prev) and to detach adhering bacteria (F-det) were evaluated for hydrophilic glass, hydrophobic, dimethyldichlorosilane (DDS)-coated glass and six different bacterial strains, in order to test the fol

  20. Forces involved in bacterial adhesion to hydrophilic and hydrophobic surfaces

    NARCIS (Netherlands)

    Boks, Niels P.; Norde, Willem; van der Mei, Henny C.; Busscher, Henk J.

    2008-01-01

    Using a parallel-plate flow chamber, the hydrodynamic shear forces to prevent bacterial adhesion (F(prev)) and to detach adhering bacteria (F(det)) were evaluated for hydrophilic glass, hydrophobic, dimethyldichlorosilane (DDS)-coated glass and six different bacterial strains, in order to test the f

  1. Evaporation Flux Distribution of Drops on a Hydrophilic or Hydrophobic Flat Surface by Molecular Simulations.

    Science.gov (United States)

    Xie, Chiyu; Liu, Guangzhi; Wang, Moran

    2016-08-16

    The evaporation flux distribution of sessile drops is investigated by molecular dynamic simulations. Three evaporating modes are classified, including the diffusion dominant mode, the substrate heating mode, and the environment heating mode. Both hydrophilic and hydrophobic drop-substrate interactions are considered. To count the evaporation flux distribution, which is position dependent, we proposed an azimuthal-angle-based division method under the assumption of spherical crown shape of drops. The modeling results show that the edge evaporation, i.e., near the contact line, is enhanced for hydrophilic drops in all the three modes. The surface diffusion of liquid molecular absorbed on solid substrate for hydrophilic cases plays an important role as well as the space diffusion on the enhanced evaporation rate at the edge. For hydrophobic drops, the edge evaporation flux is higher for the substrate heating mode, but lower than elsewhere of the drop for the diffusion dominant mode; however, a nearly uniform distribution is found for the environment heating mode. The evidence shows that the temperature distribution inside drops plays a key role in the position-dependent evaporation flux.

  2. Evaluating the hydrophilic-lipophilic nature of asphaltenic oils and naphthenic amphiphiles using microemulsion models.

    Science.gov (United States)

    Kiran, Sumit K; Acosta, Edgar J; Moran, Kevin

    2009-08-01

    Asphaltenes and naphthenic acid derivatives, which are polar and surface-active species, are known to interfere with the recovery of heavy crude oil by promoting the formation of stable emulsions. In this study, previously established microemulsion phase behavior models were applied to quantify the hydrophilic-lipophilic nature of asphaltenic oils (bitumen, deasphalted bitumen, asphalt, naphthalene) and surface-active species found in heavy oils (naphthenic compounds and asphaltenes). For the test oils, the equivalent alkane carbon number (EACN) was determined by evaluating the "salinity shifts" of microemulsions formulated with a reference surfactant (sodium dihexyl sulfosuccinate--SDHS) and a reference oil (toluene) as a function of test oil volume fraction. Similarly, the characteristic curvature (C(C)) of surface-active species was determined by evaluating the salinity shifts as a function of the molar fraction of the surface-active species in mixture with SDHS. As a part of the oil phase, asphaltenes and asphaltene-like species are highly hydrophilic, which lead to low EACN values despite their large molecular weight. As a surface-active material, asphaltenes are hydrophobic species that lead to the formation of water-in-oil emulsions. Naphthenates, particularly sodium naphthenates, are highly hydrophilic compounds that lead to the formation of oil-in-water emulsions. These hydrophilic-lipophilic characterization parameters, and the methods used to determine them, can be used in the future to understand the phase behavior of complex oil-water systems.

  3. Interplay between hydrophilicity and surface barriers on water transport in zeolite membranes

    Science.gov (United States)

    Fasano, Matteo; Humplik, Thomas; Bevilacqua, Alessio; Tsapatsis, Michael; Chiavazzo, Eliodoro; Wang, Evelyn N.; Asinari, Pietro

    2016-10-01

    A comprehensive understanding of molecular transport within nanoporous materials remains elusive in a broad variety of engineering and biomedical applications. Here, experiments and atomistic simulations are synergically used to elucidate the non-trivial interplay between nanopore hydrophilicity and surface barriers on the overall water transport through zeolite crystals. At these nanometre-length scales, these results highlight the dominating effect of surface imperfections with reduced permeability on the overall water transport. A simple diffusion resistance model is shown to be sufficient to capture the effects of both intracrystalline and surface diffusion resistances, thus properly linking simulation to experimental evidence. This work suggests that future experimental work should focus on eliminating/overcoming these surface imperfections, which promise an order of magnitude improvement in permeability.

  4. Highly selective creation of hydrophilic micro-craters on super hydrophobic surface using electrohydrodynamic jet printing

    Science.gov (United States)

    Lee, Jaehyun; Hwang, Sangyeon; Prasetyo, Fariza Dian; Nguyen, Vu Dat; Hong, Jungwoo; Shin, Jennifer H.; Byun, Doyoung

    2014-11-01

    Selective surface modification is considered as an alternative to conventional printing techniques in high resolution patterning. Here, we present fabrication of hydrophilic patterns on the super hydrophobic surface, which makes structure on the hydrophilic region. The super hydrophobic surface is able to be chemically changed to hydrophilic with alcohols. As a consecutive process, electrohydrodynamic (EHD) jet printing was utilized to fabricate local hydrophilic craters with 30-200 μm sizes. 3 kinds of target liquids were deposited well on hydrophilic region; PEDOT (poly 3,4 ethylenediocythiophene), polystyrene nano-particles, and salmonella bacteria medium. Additionally, qualitative analysis were presented for modification mechanism and surface properties on super hydrophobic/hydrophilic by analysis of surface energy with contact angle, SEM (scanning electron microscopy) image, and SIMS (secondary ion mass spectroscopy) analysis. This new simple modification method provides possibility to be utilizing in bio-patterning engineering such as cell culturing microchip and lab on a chip. This research was supported by the Basi Science Research Program through the National Research Foundation of Korea (NRF) (Grand Number: 2014-023284).

  5. Effect of Hydrophobic and Hydrophilic Surfaces on the Stability of Double-Stranded DNA.

    Science.gov (United States)

    Elder, Robert M; Pfaendtner, Jim; Jayaraman, Arthi

    2015-06-08

    DNA hybridization is the foundation for numerous technologies like DNA origami and DNA sensing/microarrays. Using molecular simulations, enhanced-sampling methods, and free-energy calculations, we show the effects of hydrophilic and hydrophobic surfaces on DNA hybridization. Hydrophilic surfaces compete with terminal bases' H-bonds but stabilize central base stacking. Hydrophobic surfaces strengthen terminal H-bonds but destabilize central base stacking. Regardless of surface chemistry, for terminal bases, melting proceeds through breaking H-bonds, followed by unstacking from the neighboring base. For central bases in bulk or near hydrophobic surfaces, melting proceeds by disruption of H-bonds, followed by unstacking, whereas on hydrophilic surfaces, unstacking from one neighboring base precedes complete disruption of the H-bonds, followed by unstacking from the second neighboring base. Kinetic barriers to melting and hybridization show that the central bases melt rapidly near hydrophobic surfaces, which can accelerate conformational searching and thereby accelerate folding into the desired conformation.

  6. Asymmetric electrostatic and hydrophobic-hydrophilic interaction forces between mica surfaces and silicone polymer thin films.

    Science.gov (United States)

    Donaldson, Stephen H; Das, Saurabh; Gebbie, Matthew A; Rapp, Michael; Jones, Louis C; Roiter, Yuri; Koenig, Peter H; Gizaw, Yonas; Israelachvili, Jacob N

    2013-11-26

    We have synthesized model hydrophobic silicone thin films on gold surfaces by a two-step covalent grafting procedure. An amino-functionalized gold surface reacts with monoepoxy-terminated polydimethylsiloxane (PDMS) via a click reaction, resulting in a covalently attached nanoscale thin film of PDMS, and the click chemistry synthesis route provides great selectivity, reproducibility, and stability in the resulting model hydrophobic silicone thin films. The asymmetric interaction forces between the PDMS thin films and mica surfaces were measured with the surface forces apparatus in aqueous sodium chloride solutions. At an acidic pH of 3, attractive interactions are measured, resulting in instabilities during both approach (jump-in) and separation (jump-out from adhesive contact). Quantitative analysis of the results indicates that the Derjaguin-Landau-Verwey-Overbeek theory alone, i.e., the combination of electrostatic repulsion and van der Waals attraction, cannot fully describe the measured forces and that the additional measured adhesion is likely due to hydrophobic interactions. The surface interactions are highly pH-dependent, and a basic pH of 10 results in fully repulsive interactions at all distances, due to repulsive electrostatic and steric-hydration interactions, indicating that the PDMS is negatively charged at high pH. We describe an interaction potential with a parameter, known as the Hydra parameter, that can account for the extra attraction (low pH) due to hydrophobicity as well as the extra repulsion (high pH) due to hydrophilic (steric-hydration) interactions. The interaction potential is general and provides a quantitative measure of interfacial hydrophobicity/hydrophilicity for any set of interacting surfaces in aqueous solution.

  7. Surface hydrophilicity of PLGA fibers governs in vitro mineralization and osteogenic differentiation.

    Science.gov (United States)

    Thomas, Minnah; Arora, Aditya; Katti, Dhirendra S

    2014-12-01

    Interfacial properties of biomaterials play an important role in governing their interaction with biological microenvironments. This work investigates the role of surface hydrophilicity of electrospun poly(lactide-co-glycolide) (PLGA) fibers in determining their biological response. For this, PLGA is blended with varying amounts of Pluronic®F-108 and electrospun to fabricate microfibers with varying surface hydrophilicity. The results of mineralization study in simulated body fluid (SBF) demonstrate a significant enhancement in mineralization with an increase in surface hydrophilicity. While presence of serum proteins in SBF reduces absolute mineral content, mineralization continues to be higher on samples with higher surface hydrophilicity. The results from in vitro cell culture studies demonstrate a marked improvement in mesenchymal stem cell-adhesion, elongation, proliferation, infiltration, osteogenic differentiation and matrix mineralization on hydrophilized fibers. Therefore, hydrophilized PLGA fibers are advantageous both in terms of mineralization and elicitation of favorable cell response. Since most of the polymeric materials being used in orthopedics are hydrophobic in nature, the results from this study have strong implications in the future design of interfaces of such hydrophobic materials. In addition, the work proposes a facile method for the modification of electrospun fibers of hydrophobic polymers by blending with a poloxamer for improved bone tissue regeneration.

  8. Novel hydrophilic nanostructured microtexture on direct metal laser sintered Ti-6Al-4V surfaces enhances osteoblast response in vitro and osseointegration in a rabbit model.

    Science.gov (United States)

    Hyzy, Sharon L; Cheng, Alice; Cohen, David J; Yatzkaier, Gustavo; Whitehead, Alexander J; Clohessy, Ryan M; Gittens, Rolando A; Boyan, Barbara D; Schwartz, Zvi

    2016-08-01

    The purpose of this study was to compare the biological effects in vivo of hierarchical surface roughness on laser sintered titanium-aluminum-vanadium (Ti-6Al-4V) implants to those of conventionally machined implants on osteoblast response in vitro and osseointegration. Laser sintered disks were fabricated to have micro-/nano-roughness and wettability. Control disks were computer numerical control (CNC) milled and then polished to be smooth (CNC-M). Laser sintered disks were polished smooth (LST-M), grit blasted (LST-B), or blasted and acid etched (LST-BE). LST-BE implants or implants manufactured by CNC milling and grit blasted (CNC-B) were implanted in the femurs of male New Zealand white rabbits. Most osteoblast differentiation markers and local factors were enhanced on rough LST-B and LST-BE surfaces in comparison to smooth CNC-M or LST-M surfaces for MG63 and normal human osteoblast cells. To determine if LST-BE implants were osteogenic in vivo, we compared them to implant surfaces used clinically. LST-BE implants had a unique surface with combined micro-/nano-roughness and higher wettability than conventional CNC-B implants. Histomorphometric analysis demonstrated a significant improvement in cortical bone-implant contact of LST-BE implants compared to CNC-B implants after 3 and 6 weeks. However, mechanical testing revealed no differences between implant pullout forces at those time points. LST surfaces enhanced osteoblast differentiation and production of local factors in vitro and improved the osseointegration process in vivo. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 2086-2098, 2016. © 2016 Wiley Periodicals, Inc.

  9. The double effects of silver nanoparticles on the PVDF membrane: Surface hydrophilicity and antifouling performance

    Science.gov (United States)

    Li, Jian-Hua; Shao, Xi-Sheng; Zhou, Qing; Li, Mi-Zi; Zhang, Qi-Qing

    2013-01-01

    In this study, silver nanoparticles were used to endow poly(vinylidene fluoride) (PVDF) membrane with excellent surface hydrophilicity and outstanding antifouling performance. Silver nanoparticles were successfully immobilized onto PVDF membrane surface under the presence of poly(acrylic acid) (PAA). The double effects of silver nanoparticles on PVDF membrane, i.e., surface hydrophilicity and anti-fouling performance, were systematically investigated. Judging from result of water static contact measurement, silver nanoparticles had provided a significant improvement in PVDF membrane surface hydrophilicity. And the possible explanation on the improvement of PVDF membrane surface hydrophilicity with silver nanoparticles was firstly proposed in this study. Membrane permeation and anti-bacterial tests were carried out to characterize the antifouling performance of PVDF membrane. Flux recovery ratio (FRR) increased about 40% after the presence of silver nanoparticles on the PVDF membrane surface, elucidating the anti-organic fouling performance of PVDF membrane was elevated by silver nanoparticles. Simultaneously, anti-bacterial test confirmed that PVDF membrane showed superior anti-biofouling activity because of silver nanoparticles. The above-mentioned results clarified that silver nanoparticles can endow PVDF membrane with both excellent surface hydrophilicity and outstanding antifouling performance in this study.

  10. A closer look at the complex hydrophilic/hydrophobic interactions forces at the human hair surface

    Science.gov (United States)

    Baghdadli, N.; Luengo, G. S.; Recherche, L.

    2008-03-01

    The complex chemical structure of the hair surface is far from being completely understood. Current understanding is based on Rivett's model1 that was proposed to explain the macroscopic hydrophobic nature of the surface of natural hair. In this model covalently-linked fatty acids are chemically grafted to the amorphous protein (keratin) through a thio-ester linkage2,3. Nevertheless, experience like wetting and electrical properties of human hair surface4 shows that the complexity of the hair surface is not fully understand based on this model in literature. Recent studies in our laboratory show for the first time microscopic evidence of the heterogeneous physico-chemical character of the hair surface. By using Chemical Force Microscopy, the presence of hydrophobic and ionic species are detected and localized, before and after a cosmetic treatment (bleaching). Based on force curve analysis the mapping of the local distribution of hydrophilic and hydrophobic groups of hair surface is obtained. A discussion on a more plausible hair model and its implications will be presented based on these new results.

  11. A closer look at the complex hydrophilic/hydrophobic interactions forces at the human hair surface

    Energy Technology Data Exchange (ETDEWEB)

    Baghdadli, N; Luengo, G S; Recherche, L [Avenue Eugene Schueller, Aulnay-Sous Bois, 93100 (France)], E-mail: nbaghdadli@rd.loreal.com, E-mail: gluengo@rd.loreal.com

    2008-03-15

    The complex chemical structure of the hair surface is far from being completely understood. Current understanding is based on Rivett's model{sup 1} that was proposed to explain the macroscopic hydrophobic nature of the surface of natural hair. In this model covalently-linked fatty acids are chemically grafted to the amorphous protein (keratin) through a thio-ester linkage{sup 2,3}. Nevertheless, experience like wetting and electrical properties of human hair surface{sup 4} shows that the complexity of the hair surface is not fully understand based on this model in literature. Recent studies in our laboratory show for the first time microscopic evidence of the heterogeneous physico-chemical character of the hair surface. By using Chemical Force Microscopy, the presence of hydrophobic and ionic species are detected and localized, before and after a cosmetic treatment (bleaching). Based on force curve analysis the mapping of the local distribution of hydrophilic and hydrophobic groups of hair surface is obtained. A discussion on a more plausible hair model and its implications will be presented based on these new results.

  12. Bond-Strengthening in Staphylococcal Adhesion to Hydrophilic and Hydrophobic Surfaces Using Atomic Force Microscopy

    NARCIS (Netherlands)

    Boks, N.P.; Busscher, H.J.; Mei, van der H.C.; Norde, W.

    2008-01-01

    Time-dependent bacterial adhesion forces of four strains of Staphylococcus epidermidis to hydrophobic and hydrophilic surfaces were investigated. Initial adhesion forces differed significantly between the two surfaces and hovered around -0.4 nN. No unambiguous effect of substratum surface

  13. Bond-Strengthening in Staphylococcal Adhesion to Hydrophilic and Hydrophobic Surfaces Using Atomic Force Microscopy

    NARCIS (Netherlands)

    Boks, Niels P.; Busscher, Henk J.; van der Mei, Henny C.; Norde, Willem

    2008-01-01

    Time-dependent bacterial adhesion forces of four strains of Staphylococcus epidermidis to hydrophobic and hydrophilic surfaces were investigated. Initial adhesion forces differed significantly between the two surfaces and hovered around -0.4 nN. No unambiguous effect of substratum surface hydrophobi

  14. Highly Hydrophilic Polyvinylidene Fluoride (PVDF) Ultrafiltration Membranes via Postfabrication Grafting of Surface-Tailored Silica Nanoparticles

    KAUST Repository

    Liang, Shuai

    2013-07-24

    Polyvinylidene fluoride (PVDF) has drawn much attention as a predominant ultrafiltration (UF) membrane material due to its outstanding mechanical and physicochemical properties. However, current applications suffer from the low fouling resistance of the PVDF membrane due to the intrinsic hydrophobic property of the membrane. The present study demonstrates a novel approach for the fabrication of a highly hydrophilic PVDF UF membrane via postfabrication tethering of superhydrophilic silica nanoparticles (NPs) to the membrane surface. The pristine PVDF membrane was grafted with poly(methacrylic acid) (PMAA) by plasma induced graft copolymerization, providing sufficient carboxyl groups as anchor sites for the binding of silica NPs, which were surface-tailored with amine-terminated cationic ligands. The NP binding was achieved through a remarkably simple and effective dip-coating technique in the presence or absence of the N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) cross-linking process. The properties of the membrane prepared from the modification without EDC/NHS cross-linking were comparable to those for the membrane prepared with the EDC/NHS cross-linking. Both modifications almost doubled the surface energy of the functionalized membranes, which significantly improved the wettability of the membrane and converted the membrane surface from hydrophobic to highly hydrophilic. The irreversibly bound layer of superhydrophilic silica NPs endowed the membranes with strong antifouling performance as demonstrated by three sequential fouling filtration runs using bovine serum albumin (BSA) as a model organic foulant. The results suggest promising applications of the postfabrication surface modification technique in various membrane separation areas. © 2013 American Chemical Society.

  15. Critical heat flux maxima resulting from the controlled morphology of nanoporous hydrophilic surface layers

    Science.gov (United States)

    Tetreault-Friend, Melanie; Azizian, Reza; Bucci, Matteo; McKrell, Thomas; Buongiorno, Jacopo; Rubner, Michael; Cohen, Robert

    2016-06-01

    Porous hydrophilic surfaces have been shown to enhance the critical heat flux (CHF) in boiling heat transfer. In this work, the separate effects of pore size and porous layer thickness on the CHF of saturated water at atmospheric pressure were experimentally investigated using carefully engineered surfaces. It was shown that, for a fixed pore diameter (˜20 nm), there is an optimum layer thickness (˜2 μm), for which the CHF value is maximum, corresponding to ˜115% enhancement over the value for uncoated surfaces. Similarly, a maximum CHF value (˜100% above the uncoated surface CHF) was observed while changing the pore size at a constant layer thickness (˜1 μm). To explain these CHF maxima, we propose a mechanistic model that can capture the effect of pore size and pore thickness on CHF. The good agreement found between the model and experimental data supports the hypothesis that CHF is governed by the competition between capillary wicking, viscous pressure drop and evaporation, as well as conduction heat transfer within the porous layer. The model can be used to guide the development of engineered surfaces with superior boiling performance.

  16. [Research development of surface hydrophilicity and lubrication modification of interventional guide wire].

    Science.gov (United States)

    Zhao, Bing; Liu, Xiaohong; Yuan, Ting

    2015-01-01

    Surface lubricity is one of the important performance criteria for interventional guide wire. In this paper, a review of the methods of surface hydrophilicity and lubrication modification of interventional guide wire is presented, including their fundamental principles, effects and some relative applications. These methods all have their own advantages and disadvantages, therefore, limitations of experimental conditions need to be taken into account.

  17. Hydrophilization of poly(ether ether ketone) films by surface-initiated atom transfer radical polymerization

    DEFF Research Database (Denmark)

    Fristrup, Charlotte Juel; Jankova Atanasova, Katja; Hvilsted, Søren

    2010-01-01

    Surface-Initiated Atom Transfer Radical Polymerization (SI-ATRP) has been exploited to hydrophilize PEEK. The ketone groups on the PEEK surface were reduced to hydroxyl groups which were converted to bromoisobutyrate initiating sites for SI-ATRP. The modification steps were followed by contact...

  18. Enhancement of Water Evaporation on Solid Surfaces with Nanoscale Hydrophobic-Hydrophilic Patterns.

    Science.gov (United States)

    Wan, Rongzheng; Wang, Chunlei; Lei, Xiaoling; Zhou, Guoquan; Fang, Haiping

    2015-11-06

    Using molecular dynamics simulations, we show that the evaporation of nanoscale water on hydrophobic-hydrophilic patterned surfaces is unexpectedly faster than that on any surfaces with uniform wettability. The key to this phenomenon is that, on the patterned surface, the evaporation rate from the hydrophilic region only slightly decreases due to the correspondingly increased water thickness; meanwhile, a considerable number of water molecules evaporate from the hydrophobic region despite the lack of water film. Most of the evaporated water from the hydrophobic region originates from the hydrophilic region by diffusing across the contact lines. Further analysis shows that the evaporation rate from the hydrophobic region is approximately proportional to the total length of the contact lines.

  19. Highly Hydrophilic Thin-Film Composite Forward Osmosis Membranes Functionalized with Surface-Tailored Nanoparticles

    KAUST Repository

    Tiraferri, Alberto

    2012-09-26

    Thin-film composite polyamide membranes are state-of-the-art materials for membrane-based water purification and desalination processes, which require both high rejection of contaminants and high water permeabilities. However, these membranes are prone to fouling when processing natural waters and wastewaters, because of the inherent surface physicochemical properties of polyamides. The present work demonstrates the fabrication of forward osmosis polyamide membranes with optimized surface properties via facile and scalable functionalization with fine-tuned nanoparticles. Silica nanoparticles are coated with superhydrophilic ligands possessing functional groups that impart stability to the nanoparticles and bind irreversibly to the native carboxyl moieties on the membrane selective layer. The tightly tethered layer of nanoparticles tailors the surface chemistry of the novel composite membrane without altering the morphology or water/solute permeabilities of the membrane selective layer. Surface characterization and interfacial energy analysis confirm that highly hydrophilic and wettable membrane surfaces are successfully attained. Lower intermolecular adhesion forces are measured between the new membrane materials and model organic foulants, indicating the presence of a bound hydration layer at the polyamide membrane surface that creates a barrier for foulant adhesion. © 2012 American Chemical Society.

  20. RF plasma based selective modification of hydrophilic regions on super hydrophobic surface

    Science.gov (United States)

    Lee, Jaehyun; Hwang, Sangyeon; Cho, Dae-Hyun; Hong, Jungwoo; Shin, Jennifer H.; Byun, Doyoung

    2017-02-01

    Selective modification and regional alterations of the surface property have gained a great deal of attention to many engineers. In this paper, we present a simple, a cost-effective, and amendable reforming method for disparate patterns of hydrophilic regions on super-hydrophobic surfaces. Uniform super-hydrophobic layer (Contact angle; CA > 150°, root mean square (RMS) roughness ∼0.28 nm) can be formed using the atmospheric radio frequency (RF) plasma on top of the selective hydrophilic (CA ∼ 70°, RMS roughness ∼0.34 nm) patterns imprinted by electrohydrodynamic (EHD) jet printing technology with polar alcohols (butyl carbitol or ethanol). The wettability of the modified surface was investigated qualitatively utilizing scanning electron microscopy (SEM), atomic force microscopy (AFM), and wavelength scanning interferometer (WSI). Secondary ion mass spectroscopy (SIMS) analysis showed that the alcohol addiction reaction changed the types of radicals on the super-hydrophobic surface. The wettability was found to depend sensitively on chemical radicals on the surface, not on surface morphology (particle size and surface roughness). Furthermore, three different kinds of representative hydrophilic samples (polystyrene nano-particle aqueous solution, Salmonella bacteria medium, and poly(3,4-ethylenediocythiophene) ink) were tested for uniform deposition onto the desired hydrophilic regions. This simple strategy would have broad applications in various research fields that require selective deposition of target materials.

  1. Nisin adsorption on hydrophilic and hydrophobic surfaces: evidence of its interactions and antibacterial activity.

    Science.gov (United States)

    Karam, Layal; Jama, Charafeddine; Nuns, Nicolas; Mamede, Anne-Sophie; Dhulster, Pascal; Chihib, Nour-Eddine

    2013-06-01

    Study of peptides adsorption on surfaces remains a current challenge in literature. A complementary approach, combining X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) was used to investigate the antimicrobial peptide nisin adsorption on hydrophilic and hydrophobic surfaces. The native low density polyethylene was used as hydrophobic support and it was grafted with acrylic acid to render it hydrophilic. XPS permitted to confirm nisin adsorption and to determine its amount on the surfaces. ToF-SIMS permitted to identify the adsorbed bacteriocin type and to observe its distribution and orientation behavior on both types of surfaces. Nisin was more oriented by its hydrophobic side to the hydrophobic substrate and by its hydrophilic side to the outer layers of the adsorbed peptide, in contrast to what was observed on the hydrophilic substrate. A correlation was found between XPS and ToF-SIMS results, the types of interactions on both surfaces and the observed antibacterial activity. Such interfacial studies are crucial for better understanding the peptides interactions and adsorption on surfaces and must be considered when setting up antimicrobial surfaces.

  2. Bionic design for surface optimization combining hydrophilic and negative charged biological macromolecules.

    Science.gov (United States)

    Ran, Fen; Song, Haiming; Niu, Xiaoqin; Yang, Aimei; Nie, Shengqiang; Wang, Lingren; Li, Jie; Sun, Shudong; Zhao, Changsheng

    2014-06-01

    While polyethersulfone (PES) membrane represents a promising option for blood purification, the blood compatibility must be dramatically enhanced to meet today's ever-increasing demands for many emerging application. In this study, we report a bionic design for optimization and development of a modified PES membrane combining hydrophilic and negative charged biological macromolecules on its surface. The hydrophilic and ionic charged biological macromolecules sulfonated poly(styrene)-b-poly(methyl methacrylate)-b-poly-(styrene) (PSSMSS) and poly(vinyl pyrrolidone)-b-poly(methyl methacrylate)-b-poly-(vinyl pyrrolidone) were synthesized via reversible addition-fragmentation chain transfer polymerization and used together to modify PES membranes by blending method. A hydrophilic membrane surface with negative charged surface coating was obtained, imitating the hydrophilic and negatively charged structure feature of heparin. The modified PES membranes showed suppressed platelet adhesion, and a prolonged blood clotting time, and thereby improved blood compatibility. In addition, the blood clotting time of the modified membranes increased with the blended PSSMSS amounts increment, indicating that both the hydrophilic and negative charged groups play important roles in improving the blood compatibility of PES membranes.

  3. Boundary slip study on hydrophilic, hydrophobic, and superhydrophobic surfaces with dynamic atomic force microscopy.

    Science.gov (United States)

    Bhushan, Bharat; Wang, Yuliang; Maali, Abdelhamid

    2009-07-21

    Slip length has been measured using the dynamic atomic force microscopy (AFM) method. Unlike the contact AFM method, the sample surface approaches an oscillating sphere with a very low velocity in the dynamic AFM method. During this process, the amplitude and phase shift data are recorded to calculate the hydrodynamic damping coefficient, which is then used to obtain slip length. In this study, a glass sphere with a large radius was glued to the end of an AFM cantilever to measure the slip length on rough surfaces. Experimental results for hydrophilic, hydrophobic, and superhydrophobic surfaces show that the hydrodynamic damping coefficient decreases from the hydrophilic surface to the hydrophobic surface and from the hydrophobic one to the superhydrophobic one. The slip lengths obtained on the hydrophobic and superhydrophobic surfaces are 43 and 236 nm, respectively, which indicates increasing boundary slip from the hydrophobic surface to the superhydrophobic one.

  4. Influence of roughness on capillary forces between hydrophilic surfaces

    NARCIS (Netherlands)

    van Zwol, P. J.; Palasantzas, G.; De Hosson, J. Th. M.

    2008-01-01

    Capillary forces have been measured by atomic force microscopy in the plate-sphere setup between gold, borosilicate glass, GeSbTe, titanium, and UV-irradiated amorphous titanium-dioxide surfaces. The force measurements were performed as a function contact time and surface roughness in the range 0.2-

  5. A Simple Hydrophilic Treatment of SU-8 Surfaces for Cell Culturing and Cell Patterning

    DEFF Research Database (Denmark)

    Wang, Zhenyu; Stangegaard, Michael; Dufva, Hans Martin

    2005-01-01

    SU-8, an epoxy-based photoresist, widely used in constitution different mTAS systems, is incompatible with mammalian cell adhesion and culture in its native form. Here, we demonstrate a simple, cheap and robust two-step method to render a SU-8 surface hydrophilic and compatible with cell culture...

  6. Protein repellent hydrophilic grafts prepared by surface-initiated atom transfer radical polymerization from polypropylene

    DEFF Research Database (Denmark)

    Fristrup, Charlotte Juel; Jankova Atanasova, Katja; Eskimergen, Rüya

    2012-01-01

    Grafting of poly(ethylene glycol)methacrylate (PEGMA) and N,N-dimethylacrylamide (DMAAm) from UV-initiator modified polypropylene (PP) was performed by Surface-Initiated Atom Transfer Radical Polymerization (SI-ATRP). The modification and hydrophilization of the PP substrates were confirmed...

  7. Patterned hydrophobic and hydrophilic surfaces of ultra-smooth nanocrystalline diamond layers

    Science.gov (United States)

    Mertens, M.; Mohr, M.; Brühne, K.; Fecht, H. J.; Łojkowski, M.; Święszkowski, W.; Łojkowski, W.

    2016-12-01

    In this work, we show that ultra nanocrystalline diamond (UNCD) surfaces have been modified to add them hydrophobic and hydrophilic properties. The nanocrystalline diamond films were deposited using the hot filament chemical vapor deposition (HFCVD) technique. This allows growing diamond on different substrates which can be even 3D or structured. Silicon and, for optical applications, transparent quartz glass are the preferred substrates for UNCD layers growth. Fluorine termination leads to strong hydrophobic properties as indicated by a high contact angle for water of more than 100°. Hydrogen termination shows lesser hydrophobic behavior. Hydrophilic characteristics has been realised with oxygen termination. X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDX) measurements confirm the oxygen and fluorine- termination on the nanocrystalline diamond surface. Further, by micropatterning using photolithography, multi-terminated layers have been created with both hydrophobic and hydrophilic areas. In addition, we have shown that retermination is achieved, and the properties of the surface have been changed from hydrophobic to hydrophilic and vice versa. Micro- roughness and stress in the grown film influences slightly the wetting angle as well. The opportunity to realize local differences in hydrophobicity on nanocrystalline diamond layers, in any size or geometry, offers interesting applications for example in microbiological investigations. Multi-terminated arrays show identical surface roughness and at the same time differences in hydrophobicity. These arrays have been visualized with scanning electron microscopy (SEM) and lateral force microscopy (LFM).

  8. A Simple Hydrophilic Treatment of SU-8 Surfaces for Cell Culturing and Cell Patterning

    DEFF Research Database (Denmark)

    Wang, Zhenyu; Stangegaard, Michael; Dufva, Hans Martin;

    2005-01-01

    SU-8, an epoxy-based photoresist, widely used in constitution different mTAS systems, is incompatible with mammalian cell adhesion and culture in its native form. Here, we demonstrate a simple, cheap and robust two-step method to render a SU-8 surface hydrophilic and compatible with cell culture...

  9. The hydrophobic effect: Molecular dynamics simulations of water confined between extended hydrophobic and hydrophilic surfaces

    DEFF Research Database (Denmark)

    Jensen, Morten Østergaard; Mouritsen, Ole G.; Peters, Günther H.J.

    2004-01-01

    experimental data from x-ray reflectivity measurements, reveal a uniform weak de-wetting characteristic for the extended hydrophobic surface, while the hydrophilic surface is weakly wetted. These microscopic data are consistent with macroscopic contact angle measurements. Specific water orientation is present......-correlation functions reveal that water molecules have characteristic diffusive behavior and orientational ordering due to the lack of hydrogen bonding interactions with the surface. These observations suggest that the altered dynamical properties of water in contact with extended hydrophobic surfaces together......Structural and dynamic properties of water confined between two parallel, extended, either hydrophobic or hydrophilic crystalline surfaces of n-alkane C36H74 or n-alcohol C35H71OH, are studied by molecular dynamics simulations. Electron density profiles, directly compared with corresponding...

  10. Hydrophilic modification of polyester fabric by applying nanocrystalline cellulose containing surface finish.

    Science.gov (United States)

    Zaman, Masuduz; Liu, Hongbin; Xiao, Huning; Chibante, Felipe; Ni, Yonghao

    2013-01-16

    In this study, polyethylene terephthalate (PET) fabric was modified by applying a hydrophilic surface finishing agent that contains nanocrystalline cellulose (NCC). To impart superior hydrophilicity, NCC was further cationically modified through quaternization by grafting glycidyl tri-methyl ammonium chloride (GTMAC). A textile binder, PrintRite595(®), was added to the finishing system. The surface finish was applied on the fabric using a rolling-drying-curing process. The modified fabric was characterized in terms of coating durability, moisture regain, and wettability. The durability of the surface finish was tested by six repeated washing steps. The surface properties of the fabric changed from hydrophobic to hydrophilic after heat treatment with the NCC-containing surface finishing agent. The results from the washing fastness, SEM, FTIR, and EDX analyses confirmed that the cationic NCC-containing textile surface finish showed superior adhesion onto the cationic dyeable (anionic) PET surface over the un-modified NCC. Furthermore, the cationic textile surface finish was capable of withstanding multiple washing cycles. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Highly stable hydrophilic surfaces of PDMS thin layer obtained by UV radiation and oxygen plasma treatments

    Energy Technology Data Exchange (ETDEWEB)

    Menezes Atayde, Cleuson de; Doi, Ioshiaki [Center for Semiconductor Components, University of Campinas - UNICAMP, Campinas, SP (Brazil); School of Electrical and Computer Engineering, University of Campinas - UNICAMP, Campinas, SP (Brazil)

    2010-02-15

    Surface modification of polydimethylsiloxane (PDMS, Sylgard 184) was carried out by O{sub 2} plasma and UV in broadband mode/O{sub 2} plasma treatments with different exposure times, and studied in terms of hydrophilic stability. Water contact angle measurements, Fourier Transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM) were used for the analysis of the modified surface and hydrophilic stability of the PDMS films. The results show reasonably good hydrophilic stability in the range of a week with a contact angle of around 70 for O{sub 2} plasma treated samples, whereas a more high hydrophilic stability, with a low contact angle of 65 up to 15 days, was observed for UV/O{sub 2} plasma treated PDMS. FTIR analysis of the samples reveals significant oxidation noted by large presence of Si-O-Si, and Si-OH bonds on the PDMS surface, which improves the affinity with water molecules and increases the hydrophilicy. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. Dynamics of formation of the Exclusion Zone near hydrophilic surfaces

    Science.gov (United States)

    De Ninno, Antonella

    2017-01-01

    EZ water is unable to host solutes, what provides the root of the name Exclusion Zone, and its formation law points towards a diffusive process. These peculiarities have attracted the interest of scientists because it challenges all the theories which have tried to describe the structure of liquid water. The mixture of H-bond stable and H-bond distorted structures envisaged by very recent experimental findings, cannot account for the long-lived hexagonal configuration observed near the Nafion surface. A theoretical account for the phenomenology of H-bond is provided which looks able to explain many among the most striking feature of this water.

  13. Probing the contribution of different intermolecular forces to the adsorption of spheroproteins onto hydrophilic surfaces.

    Science.gov (United States)

    Borges, João; Campiña, José M; Silva, A Fernando

    2013-12-27

    Protein adsorption is a delicate process, which results from the balance between the properties of proteins and their solid supports. Although the relevance of some of these parameters has been already unveiled, the precise involvement of electrostatics and other weaker intermolecular forces requires further comprehension. Aiming to contribute to this task, this work explores the attachment, rearrangement, and surface aggregation of a model spheroprotein, such as bovine β-lactoglobulin (β-LG), onto hydrophilic substrates prefunctionalized with different alkylthiol films. Thereby, a variety of electrostatic scenarios for the adsorption of β-LG could be recreated through the variation of the pH and the functional chemistry of the surfaces. The changes in surface mass density (plus associated water) and film flexibility were followed in situ with quartz crystal microbalance with dissipation monitoring. Film packing and aggregation were assessed by faradaic electrochemical measurements and ex situ atomic force microscopy and field effect scanning electron microscopy. In contrast to previous hypotheses arguing that electrostatic interactions between charged substrates and proteins would be the only driving force, a complex interplay between Coulombic and non-Coulombic intermolecular forces (which would depend upon the experimental conditions) has been suggested to explain the results.

  14. Mobile and immobile adhesion of staphylococcal strains to hydrophilic and hydrophobic surfaces.

    Science.gov (United States)

    Boks, Niels P; Kaper, Hans J; Norde, Willem; van der Mei, Henny C; Busscher, Henk J

    2009-03-01

    Staphylococcus epidermidis adheres to hydrophilic glass and hydrophobic dimethyldichlorosilane (DDS)-coated glass in similar numbers, but in different modes. Real-time observation of staphylococcal adhesion under a shear rate of 15 s(-1) revealed different adhesion dynamics on both substrata. The number of adsorption and desorption events to achieve a similar number of adhering bacteria was twofold higher on hydrophilic than on hydrophobic DDS-coated glass. Moreover, 22% of all staphylococci on glass slid over the surface prior to adhering on a fixed site ("mobile adhesion mode"), but mobile adhesion was virtually absent (1%) on DDS-coated glass. Sliding preceded desorption on hydrophilic glass in about 20% of all desorption events, while on hydrophobic DDS-coated glass 2% of all staphylococci desorbed straight from their adhesion site. Since acid-base interactions between the staphylococci and a hydrophobic DDS-coating are attractive, it is suggested that these interactions facilitate a closer approach of the bacteria and therewith enhance immobile adhesion at local, high affinity sites. Alternatively, if the local site is low affinity, this may lead to desorption. In the absence of attractive acid-base interactions, as on hydrophilic glass, bacteria can be captured in the minimum of the DLVO-interaction energy curve, but this does not prevent them from sliding under flow at a fixed distance from a substratum surface until immobilization or desorption at or from a local high or low affinity site, respectively.

  15. Trace Material Capture by Controlled Liquid Droplets on a Superhydrophobic/Hydrophilic Surface.

    Science.gov (United States)

    Fukada, Kenta; Kawamura, Naoya; Shiratori, Seimei

    2017-09-15

    A liquid droplet in contact with a superhydrophobic surface can be used to collect dissolved trace materials after evaporating the solvent. This process effect enhances detection limits, but a liquid droplet easily rolls off a superhydrophobic surface. Keeping it at a specific collecting spot area is challenging. Here the means for controlling and capturing a liquid droplet on a superhydrophobic surface is demonstrated. To induce a liquid droplet to a collecting spot, its rolling direction was controlled by two superhydrophobic fabric guides. The liquid droplet was then captured by hydrophilic polymer and hydrophilic nanoparticles at the measuring spot. After removing the solvent, the trace compounds were evaluated with a colorimetric analysis visible to the naked eye.

  16. Behavior of particles in an evaporating didisperse colloid droplet on a hydrophilic surface.

    Science.gov (United States)

    Jung, Jung-Yeul; Kim, Young Won; Yoo, Jung Yul

    2009-10-01

    It is well-known that the liquid and the nanoparticles in an evaporating colloid droplet on a hydrophilic surface move radially outward for the contact line to maintain its position. However, the motion of micro/nanoparticles in an evaporating didisperse colloid droplet has not been reported to date. In this study, an experiment on an evaporating didisperse colloid droplet on the hydrophilic surface is carried out. It is found that nanoparticles move radially outward and remain at the contact line while microparticles move inward toward the center of the droplet. Furthermore, the mechanism of the microparticles moving toward the center of the droplet is found to be due to the surface tension force of the liquid.

  17. Molecular explanation for why talc surfaces can be both hydrophilic and hydrophobic

    CERN Document Server

    Rotenberg, Benjamin; Chandler, David

    2011-01-01

    While individual water molecules adsorb strongly on a talc surface (hydrophilic behavior), a droplet of water beads up on the same surface (hydrophobic behavior). To rationalize this dichotomy, we investigate the influence of the microscopic structure of the surface and the strength of adhesive (surface-water) interactions on surface hydrophobicity. We show that at low relative humidity, the competition between adhesion and the favorable entropy of being in the vapor phase determines the surface coverage. However, at saturation, it is the competition between adhesion and cohesion (water-water interactions) that determines surface hydrophobicity. The adhesive interactions in talc are strong enough to overcome the unfavorable entropy, and water adsorbs strongly on talc surfaces. However, they are too weak to overcome the cohesive interactions, and water thus beads up on talc surfaces. Surprisingly, even (talc-like) surfaces that are highly adhesive, do not fully wet at saturation. Instead, a water droplet forms...

  18. Adsorption of ethyl cellulose on asphaltene- or bitumen-coated hydrophilic silica surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shengqun; Segin, Nataliya; Wang, Ke; Masliyah, Jacob H.; Xu, Zhenghe [Department of Chemical and Materials Engineering, University of Alberta (Canada)], email: zhenghe.xu@ualberta.ca

    2010-07-01

    Previous studies show that ethyl cellulose (EC) is a biodegradable, greener demulsifier for water-oil emulsions that significantly reduces diluted bitumen-water interfacial tension. In this study, the molecular mechanism of EC demulsifiers is investigated using an atomic force microscope (AFM) and a quartz crystal microbalance (QCM). Asphaltenes and bitumen were adsorbed from toluene on a hydrophilic silica wafer, which was soaked in an EC-in-toluene solution for varying periods of time. The EC gradually displaced the asphaltene/bitumen aggregates, pushing them into larger aggregates. The process reached equilibrium in about 7 hours, with EC covering most of the silica surface with large, sporadically scattered aggregates. The EC-dominated surface became more hydrophilic than asphaltene/bitumen-adsorbed surfaces. The QCM study showed that the displacement of pre-adsorbed asphaltenes by EC is irreversible. The affinity of EC to hydrophilic silica surface is stronger than that of asphaltenes, providing further insights into demulsification mechanisms of EC for breaking w/o emulsions. EC also has potential in altering a solid from oil-wet to water-wet.

  19. New approach of long-term modification of Topas® to acquire surface hydrophilicity for chromosome spreading

    DEFF Research Database (Denmark)

    Mednova, Olga; Kwasny, Dorota; Rozlosnik, Noemi;

    2014-01-01

    A modified and improved photografting procedure of Topas® surface hydrophilization is investigated in order to obtain stable modification of the polymer for long term storage. The achieved hydrophilicity and monitoring of the wettability during one month of storage are presented as well as a desc...

  20. From hydration repulsion to dry adhesion between asymmetric hydrophilic and hydrophobic surfaces.

    Science.gov (United States)

    Kanduč, Matej; Netz, Roland R

    2015-10-01

    Using all-atom molecular dynamics (MD) simulations at constant water chemical potential in combination with basic theoretical arguments, we study hydration-induced interactions between two overall charge-neutral yet polar planar surfaces with different wetting properties. Whether the water film between the two surfaces becomes unstable below a threshold separation and cavitation gives rise to long-range attraction, depends on the sum of the two individual surface contact angles. Consequently, cavitation-induced attraction also occurs for a mildly hydrophilic surface interacting with a very hydrophobic surface. If both surfaces are very hydrophilic, hydration repulsion dominates at small separations and direct attractive force contribution can-if strong enough-give rise to wet adhesion in this case. In between the regimes of cavitation-induced attraction and hydration repulsion we find a narrow range of contact angle combinations where the surfaces adhere at contact in the absence of cavitation. This dry adhesion regime is driven by direct surface-surface interactions. We derive simple laws for the cavitation transition as well as for the transition between hydration repulsion and dry adhesion, which favorably compare with simulation results in a generic adhesion state diagram as a function of the two surface contact angles.

  1. A thin transition film formed by plasma exposure contributes to the germanium surface hydrophilicity

    Science.gov (United States)

    Shumei, Lai; Danfeng, Mao; Zhiwei, Huang; Yihong, Xu; Songyan, Chen; Cheng, Li; Wei, Huang; Dingliang, Tang

    2016-09-01

    Plasma treatment and 10% NH4OH solution rinsing were performed on a germanium (Ge) surface. It was found that the Ge surface hydrophilicity after O2 and Ar plasma exposure was stronger than that of samples subjected to N2 plasma exposure. This is because the thin GeO x film formed on Ge by O2 or Ar plasma is more hydrophilic than GeO x N y formed by N2 plasma treatment. A flat (RMS direct wafer bonding. Project supported by the Key Project of Natural Science Foundation of China (No. 61534005), the National Science Foundation of China (No. 61474081), the National Basic Research Program of China (No. 2013CB632103), the Natural Science Foundation of Fujian Province (No. 2015D020), and the Science and Technology Project of Xiamen City (No. 3502Z20154091).

  2. HYDROPHILIC MODIFICATION OF PPESK POROUS MEMBRANES VIA AQUEOUS SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION

    Institute of Scientific and Technical Information of China (English)

    Zhuan Yi; You-yi Xu; Li-ping Zhu; Han-bang Dong; Bao-ku Zhu

    2009-01-01

    Hydrophilic surface modification of poly(phthalazinone ether sulfone ketone)(PPESK)porous membranes was achieved via surface-initiated atom transfer radical polymerization(ATRP)in aqueous medium.Prior to ATRP,chloromethyl groups were introduced onto PPESK main chains by chloromethylation.Chloromethylated PPESK(CMPPESK)was fabricated into porous membrane through phase inversion technique.Hydrophilic poly(poly(ethylene glycol)methyl ether methacrylate)(P(PEGMA))brushes were grafted from CMPPESK membrane under the initiation of benzyl chloride groups on membrane surface.The results of Fourier transform infrared(FT-IR)spectroscopy and X-ray photoelectron spectroscopy (XPS)confirmed the grafting of P(PEGMA)chains.Water contact angle measurements and protein adsorption experiments suggested that the hydrophilicity and anti-fouling ability of PPESK membrane were remarkably improved after the grafting of P(PEGMA)brushes.The addition of small amount of water in the reaction solvent apparently accelerated the progress of the grafting reaction.The use of CuCl2 in the catalyst system promoted the controllability of the ATRP reaction.

  3. Novel lubricated surface of titanium alloy based on porous structure and hydrophilic polymer brushes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Kun; Xiong, Dangsheng, E-mail: xiongds@163.com; Niu, Yuxiang

    2014-10-30

    Graphical abstract: - Highlights: • Lubricated Ti6Al4V was fabricated by anodic oxidation and hydrophilic polymer grafting. • Surface composition and tribological properties were estimated. • Proper surface micropores formed at optimum voltage of 100 V. • Combined effect of porous structure and polymer brushes decreased friction coefficient and wear. • Hydrated lubricating layer and hydrodynamic lubrication contributed to lubricated surface. - Abstract: On the purpose of improving the tribological properties of titanium alloy through mimicking natural articular cartilage, porous structure was prepared on the surface of Ti6Al4V alloy by anodic oxidation method, and then hydrophilic polymer brushes were grafted onto its surface. Surface morphology of porous oxidized film was investigated by metalloscope and scanning electron microscope (SEM). The composition and structure of modified surface were characterized by Fourier-transform infrared spectroscopy with attenuated total reflection (FTIR/ATR), and the wettability was also evaluated. Friction and wear properties of modified alloys sliding against ultra-high molecular weight polyethylene (UHMWPE) were tested by a pin-on-disc tribometer in physiological saline. The results showed that, the optimum porous structure treated by anodic oxidation formed when the voltage reached as high as 100 V. Hydrophilic monomers [Acrylic acid (AA) and 3-dimethyl-(3-(N-methacrylamido) propyl) ammonium propane sulfonate (DMMPPS)] were successfully grafted onto porous Ti6Al4V surface to form polymer brushes by UV radiation. The change of contact angle showed that wettability of modified Ti6Al4V was improved significantly. The friction coefficient of modified Ti6Al4V was much lower and more stable than untreated ones. The lowest friction coefficient was obtained when the sample was anodized at 100 V and grafted with DMMPPS, and the value was 0.132. The wear of modified samples was also obviously improved.

  4. Novel combination of hydrophilic/hydrophobic surface for large wettability difference and its application to liquid manipulation.

    Science.gov (United States)

    Kobayashi, Taizo; Shimizu, Kazunori; Kaizuma, Yoshihiro; Konishi, Satoshi

    2011-02-21

    This paper reports a novel combination of hydrophilic/hydrophobic materials for the evolution of liquid manipulation. Droplet generation based on a hydrophilic/hydrophobic mechanism is a promising method for highly accurate liquid manipulations. Although several droplet manipulation devices utilizing hydrophilic/hydrophobic patterns have been reported, it has been difficult to split fluid into droplets solely through hydrophilic/hydrophobic patterns in a microchannel. In this study, a material combination for fabricating hydrophilic/hydrophobic patterns was investigated and their wettability difference was enhanced for droplet generation. To improve hydrophilicity, we attempted to increase the surface area of silicon oxide through pulsed plasma chemical vapor deposition (PPCVD). To improve hydrophobicity, the damage to the hydrophobic patterns in the fabrication process was reduced. We successfully enhanced the difference in contact angles from 54.3° to 86.6° by combining the developed hydrophilic material and hydrophobic material. The developed material combination could successfully split fluid into a quantitative droplet of 14.1 nL in a microfluidic chip. Because the developed hydrophilic/hydrophobic combination enables the formation of a droplet with desirable shape in microchannels, the developed hydrophilic/hydrophobic combination is a promising component for lab-on-a-chip applications.

  5. Using in situ X-ray reflectivity to study protein adsorption on hydrophilic and hydrophobic surfaces: benefits and limitations.

    Science.gov (United States)

    Richter, Andrew G; Kuzmenko, Ivan

    2013-04-30

    We have employed in situ X-ray reflectivity (IXRR) to study the adsorption of a variety of proteins (lysozyme, cytochrome c, myoglobin, hemoglobin, serum albumin, and immunoglobulin G) on model hydrophilic (silicon oxide) and hydrophobic surfaces (octadecyltrichlorosilane self-assembled monolayers), evaluating this recently developed technique for its applicability in the area of biomolecular studies. We report herein the highest resolution depiction of adsorbed protein films, greatly improving on the precision of previous neutron reflectivity (NR) results and previous IXRR studies. We were able to perform complete scans in 5 min or less with the maximum momentum transfer of at least 0.52 Å(-1), allowing for some time-resolved information about the evolution of the protein film structure. The three smallest proteins (lysozyme, cytochrome c, and myoglobin) were seen to deposit as fully hydrated, nondenatured molecules onto hydrophilic surfaces, with indications of particular preferential orientations. Time evolution was observed for both lysozyme and myoglobin films. The larger proteins were not observed to deposit on the hydrophilic substrates, perhaps because of contrast limitations. On hydrophobic surfaces, all proteins were seen to denature extensively in a qualitatively similar way but with a rough trend that the larger proteins resulted in lower coverage. We have generated high-resolution electron density profiles of these denatured films, including capturing the growth of a lysozyme film. Because the solution interface of these denatured films is diffuse, IXRR cannot unambiguously determine the film extent and coverage, a drawback compared to NR. X-ray radiation damage was systematically evaluated, including the controlled exposure of protein films to high-intensity X-rays and exposure of the hydrophobic surface to X-rays before adsorption. Our analysis showed that standard measuring procedures used for XRR studies may lead to altered protein films

  6. Adsorption of an endoglucanase from the hyperthermophilic Pyrococcus furiosus of hydrophobic (polysterene) and hydrophilic (silica) surfaces increases protein heat stability

    NARCIS (Netherlands)

    Koutsopoulos, S.; Oost, van der J.; Norde, W.

    2004-01-01

    The interaction of an endoglucanase from the hyperthermophilic microorganism Pyrococcus furiosus with two types of surfaces, that is, hydrophobic polystyrene and hydrophilic silica, was investigated, and the adsorption isotherms were determined. The adsorbed hyperthermostable enzyme did not undergo

  7. Adsorption of an endoglucanase from the hyperthermophilic Pyrococcus furiosus on hydrophobic (polystyrene) and hydrophilic (silica) surfaces increases protein heat stability

    NARCIS (Netherlands)

    Koutsopoulos, S.; van der Oost, J.; Norde, Willem

    2004-01-01

    The interaction of an endoglucanase from the hyperthermophilic microorganism Pyrococcus furiosus with two types of surfaces, that is, hydrophobic polystyrene and hydrophilic silica, was investigated, and the adsorption isotherms were determined. The adsorbed hyperthermostable enzyme did not undergo

  8. CFD analysis of Newtonian and non-Newtonian droplets impinging on heated hydrophilic and hydrophobic surfaces

    Science.gov (United States)

    Khojasteh, Danial; Mousavi, Seyed Mahmood; Kamali, Reza

    2016-11-01

    In the present study, the behaviors of Newtonian and shear-thinning non-Newtonian droplets impinging on heated hydrophilic and hydrophobic surfaces have been investigated numerically using Ansys-Fluent. In this context, the volume-of-fluid technique is applied to track the free-surface of the liquid, and variable time-step is also utilized to control the Courant number. Furthermore, we have considered the dependence of viscosity, density and surface tension on temperature during the simulation. The results are compared to available experimental data at the same conditions, such as boundary conditions. The results demonstrate that there is a good agreement between the obtained results and the experimental trends, concerning normalized diameter profiles at various Weber numbers. Therefore, the focus of the present study is an assessment of the effects of variations in Weber number, contact angle and surface temperature for Newtonian and non-Newtonian liquids on dynamics behavior of droplet in collision with hydrophobic and hydrophilic surfaces. The results represent that the behaviors of Newtonian and non-Newtonian droplets are totally different, indicating the droplet sensitivity to the working parameters.

  9. Study of surface-bonded dicationic ionic liquids as stationary phases for hydrophilic interaction chromatography.

    Science.gov (United States)

    Qiao, Lizhen; Li, Hua; Shan, Yuanhong; Wang, Shuangyuan; Shi, Xianzhe; Lu, Xin; Xu, Guowang

    2014-02-21

    In the present study, several geminal dicationic ionic liquids based on 1,4-bis(3-allylimidazolium)butane and 1,8-bis(3-allylimidazolium)octane in combination with different anions bromide and bis(trifluoromethanesulphonyl)imide were prepared and then bonded to the surface of 3-mercaptopropyl modified silica materials through the "thiol-ene" click chemistry as stationary phases for hydrophilic interaction chromatography (HILIC). Compared with their monocationic analogues, the dicationic ionic liquids stationary phases presented effective retention and good selectivity for typical hydrophilic compounds under HILIC mode with the column efficiency as high as 130,000 plates/m. Moreover, the influence of different alkyl chain spacer between dications and combined anions on the retention behavior and selectivity of the dicationic ionic liquids stationary phases under HILIC mode was displayed. The results indicated that the longer linkage chain would decrease the hydrophilicity and retention on the dicationic ionic liquid stationary phase, and while differently combined anions had no difference due to the exchangeability under the common HILIC mobile phase with buffer salt. Finally, the retention mechanism was investigated by evaluating the effect of chromatographic factors on retention, including the water content in the mobile phase, the mobile phase pH and buffer salt concentration. The results showed that the dicationic ionic liquids stationary phases presented a mixed-mode retention behavior with HILIC mechanism and anion exchange.

  10. The effect of polymer surface modification on polymer-protein interaction via interfacial polymerization and hydrophilic polymer grafting

    Science.gov (United States)

    Protein membrane separation is prone to fouling on the membrane surface resulting from protein adsorption onto the surface. Surface modification of synthetic membranes is one way to reduce fouling. We investigated surface modification of polyethersulfone (PES) as a way of improving hydrophilicity ...

  11. Molecular dynamics simulations of water on a hydrophilic silica surface at high air pressures

    DEFF Research Database (Denmark)

    Zambrano, H.A.; Walther, Jens Honore; Jaffe, R.L.

    2014-01-01

    of air in water at different pressures. Using the calibrated force field, we conduct MD simulations to study the interface between a hydrophilic silica substrate and water surrounded by air at different pressures. We find that the static water contact angle is independent of the air pressure imposed......Wepresent a force field forMolecular Dynamics (MD) simulations ofwater and air in contactwith an amorphous silica surface. We calibrate the interactions of each species present in the systemusing dedicated criteria such as the contact angle of a water droplet on a silica surface, and the solubility...... on the system. Our simulations reveal the presence of a nanometer thick layer of gas at the water–silica interface. We believe that this gas layer could promote nucleation and stabilization of surface nanobubbles at amorphous silica surfaces. © 2014 Elsevier B.V. All rights reserved....

  12. Bubble dynamics and heat transfer for pool boiling on hydrophilic, superhydrophobic and biphilic surfaces

    Science.gov (United States)

    Teodori, E.; Palma, T.; Valente, T.; Moita, A. S.; Moreira, A. L. N.

    2016-09-01

    This paper proposes a detailed analysis of bubble dynamics to describe pool boiling heat transfer in extreme wetting scenarios (superhydrophobic vs hydrophilic). A mechanistic approach, based on extensive post-processing allows quantifying the relative advantage of the superhydrophobic surfaces to endorse the onset of boiling at very low superheats (1-2K) vs their worse heat transfer performance associated to the swift formation of an insulating vapour film. Based on this analysis, a simple biphilic surface is created. The results suggest that for high heat fluxes, bubble dynamics is dominated by the emission of very small bubbles, which seems to affect the interaction mechanisms, precluding the emission of the large bubbles from the surface, thus compromising the good performance of the biphilic surfaces.

  13. Expression of a hydrophilic surface protein in infective stages of Leishmania major.

    Science.gov (United States)

    Flinn, H M; Rangarajan, D; Smith, D F

    1994-06-01

    A family of differentially expressed genes from Leishmania major contains one sequence (Gene B) that encodes a novel, hydrophilic protein found on the surface of infective parasite stages. The 177-residue, acidic Gene B protein is characterised by an amino acid repetitive element, comprising 45% of the total molecule, that is related to the cell-wall binding domain of protein A from Staphylococcus aureus. No identifiable signal peptide, membrane-spanning domain or consensus for glycosylphosphatidylinositol anchor attachment to the cell surface is found elsewhere in the deduced protein sequence. In vitro, the Gene B protein fractionates with the parasite cell surface glycoconjugates, lipophosphoglycan and the glycoinositolphospholipids. This protein is the first characterised surface peptide marker for infective stages of the Leishmania life cycle.

  14. Surface modification with both phosphorylcholine and stearyl groups to adjust hydrophilicity and hydrophobicity

    Energy Technology Data Exchange (ETDEWEB)

    Lv Jiuan; Ma Jiani; Huangfu Pengbo; Yang Shan [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry, Northwest University, Xi' an 710069 (China); Gong Yongkuan [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, Department of Chemistry, Northwest University, Xi' an 710069 (China)], E-mail: gongyk@nwu.edu.cn

    2008-11-15

    A new monolayer film with tunable hydrophilicity and hydrophobicity was constructed on glass coverslips by stepwise grafting with both phosphorylcholine (PC) and stearyl groups. The glass coverslips were firstly hydroxylized to provide reactive sites on the surfaces. Subsequently, chlorodimethyl-n-octadecylsilane was chemically adsorbed onto the surface to impart the required hydrophobicity. The remaining hydroxyl groups were grafted with 1,6-diisocyanatohexane. Finally, 2-hydroxy-2-ethylphosphorylcholine was grafted onto the attached isocyanate groups. Dynamic contact angle (DCA) measurement and X-ray photoelectron spectroscopy (XPS) analysis confirmed that the step-by-step modification process was successful. The adsorption of bovine serum albumin and bovine plasma fibrinogen, as well as the adhesion and aggregation of platelets were suppressed with the introduction of phospholipid moieties on the surfaces. This tunable surface may have potential applications in the fields of separation science, tissue engineering, cytobiology, drug delivery and gene therapy.

  15. Hydrophilic modification of polyethersulfone porous membranes via a thermal-induced surface crosslinking approach

    Science.gov (United States)

    Mu, Li-Jun; Zhao, Wen-Zhen

    2009-05-01

    A thermal-induced surface crosslinking process was employed to perform a hydrophilic surface modification of PES porous membranes. Difunctional poly(ethylene glycol) diacrylate (PEGDA) was used as the main crosslinking modifier. The addition of trifunctional trimethylolpropane trimethylacrylate (TMPTMA) into the reaction solutions accelerated the crosslinking progress of PEGDA on PES membranes. The membrane surface morphology and chemical composition were characterized by scanning electron microscopy (SEM) and FTIR-ATR spectroscopy. The mass gains (MG) of the modified membranes could be conveniently modulated by varying the PEGDA concentration and crosslinking time. The measurements of water contact angle showed that the hydrophilicity of PES membranes was remarkably enhanced by the coating of crosslinked PEGDA layer. When a moderate mass gain of about 150 μg/cm 2 was reached, both the permeability and anti-fouling ability of PES membranes could be significantly improved. Excessive mass gain not only contributed little to the anti-fouling ability, but also brought a deteriorated permeability to PES membranes.

  16. Electrically polarized micro-arc oxidized TiO2 coatings with enhanced surface hydrophilicity.

    Science.gov (United States)

    Ma, Chufan; Nagai, Akiko; Yamazaki, Yuko; Toyama, Takeshi; Tsutsumi, Yusuke; Hanawa, Takao; Wang, Wei; Yamashita, Kimihiro

    2012-02-01

    The use of micro-arc oxidation titania (MAO TiO2) coatings to modify titanium surfaces improves the biocompatibility of implant surfaces. To obtain hydrophilic MAO TiO2 coating surfaces electric polarization, which induces surface electric fields in the materials and produces surface charges, was performed in this study. Electric polarization of the MAO TiO2 coatings was confirmed by measuring the thermally stimulated depolarization current. After electric polarization treatment the MAO TiO2 coatings did not exhibit any obvious changes in surface roughness, morphology, or phase components. X-ray photoelectron spectroscopy results indicated that electric polarization resulted in oxidation of the cathodic-faced surfaces and reduction of the anodic-faced surfaces. This result suggests that the existence of a concentration gradient of oxide ions/oxygen vacancies produced the stored space charge in the coatings. Reduction of the deionized water contact angle on the polarized MAO TiO2 surfaces was maintained for longer periods compared with the non-polarized surface. Our study demonstrated that metastable electric fields across the MAO TiO2 coating produced by electric polarization made it durably wettable by reducing the interfacial surface tension between the material and water.

  17. Reversible Interactions of Proteins with Mixed Shell Polymeric Micelles: Tuning the Surface Hydrophobic/Hydrophilic Balance toward Efficient Artificial Chaperones.

    Science.gov (United States)

    Wang, Jianzu; Song, Yiqing; Sun, Pingchuan; An, Yingli; Zhang, Zhenkun; Shi, Linqi

    2016-03-22

    Molecular chaperones can elegantly fine-tune its hydrophobic/hydrophilic balance to assist a broad spectrum of nascent polypeptide chains to fold properly. Such precious property is difficult to be achieved by chaperone mimicking materials due to limited control of their surface characteristics that dictate interactions with unfolded protein intermediates. Mixed shell polymeric micelles (MSPMs), which consist of two kinds of dissimilar polymeric chains in the micellar shell, offer a convenient way to fine-tune surface properties of polymeric nanoparticles. In the current work, we have fabricated ca. 30 kinds of MSPMs with finely tunable hydrophilic/hydrophobic surface properties. We investigated the respective roles of thermosensitive and hydrophilic polymeric chains in the thermodenaturation protection of proteins down to the molecular structure. Although the three kinds of thermosensitive polymers investigated herein can form collapsed hydrophobic domains on the micellar surface, we found distinct capability to capture and release unfolded protein intermediates, due to their respective affinity for proteins. Meanwhile, in terms of the hydrophilic polymeric chains in the micellar shell, poly(ethylene glycol) (PEG) excels in assisting unfolded protein intermediates to refold properly via interacting with the refolding intermediates, resulting in enhanced chaperone efficiency. However, another hydrophilic polymer-poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) severely deteriorates the chaperone efficiency of MSPMs, due to its protein-resistant properties. Judicious combination of thermosensitive and hydrophilic chains in the micellar shell lead to MSPM-based artificial chaperones with optimal efficacy.

  18. Surface morphological modification of crosslinked hydrophilic co-polymers by nanosecond pulsed laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Primo, Gastón A.; Alvarez Igarzabal, Cecilia I. [IMBIV (CONICET), Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Edificio de Ciencias II, Ciudad Universitaria, Córdoba X5000HUA (Argentina); Pino, Gustavo A.; Ferrero, Juan C. [INFIQC (CONICET), Departamento de Fisicoquímica, Facultad de Ciencias Químicas, and Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Córdoba X5000IUS (Argentina); Rossa, Maximiliano, E-mail: mrossa@fcq.unc.edu.ar [INFIQC (CONICET), Departamento de Fisicoquímica, Facultad de Ciencias Químicas, and Centro Láser de Ciencias Moleculares, Universidad Nacional de Córdoba, Córdoba X5000IUS (Argentina)

    2016-04-30

    Graphical abstract: - Highlights: • Laser-induced surface modification of crosslinked hydrophilic co-polymers by ns pulses. • Formation of ablation craters observed under most of the single-pulse experimental conditions. • UV laser foaming of dried hydrogel samples resulting from single- and multiple-pulse experiments. • Threshold values of the incident laser fluence reported for the observed surface modifications. • Lower threshold fluences for acrylate-based, compared to acrylamide-based hydrogels. - Abstract: This work reports an investigation of the surface modifications induced by irradiation with nanosecond laser pulses of ultraviolet and visible wavelengths on crosslinked hydrophilic co-polymeric materials, which have been functionalized with 1-vinylimidazole as a co-monomer. A comparison is made between hydrogels differing in the base co-monomer (N,N-dimethylaminoethyl methacrylate and N-[3-(dimethylamino)propyl] methacrylamide) and in hydration state (both swollen and dried states). Formation of craters is the dominant morphological change observed by ablation in the visible at 532 nm, whereas additional, less aggressive surface modifications, chiefly microfoams and roughness, are developed in the ultraviolet at 266 nm. At both irradiation wavelengths, threshold values of the incident laser fluence for the observation of the various surface modifications are determined under single-pulse laser irradiation conditions. It is shown that multiple-pulse irradiation at 266 nm with a limited number of laser shots can be used alternatively for generating a regular microfoam layer at the surface of dried hydrogels based on N,N-dimethylaminoethyl methacrylate. The observations are rationalized on the basis of currently accepted mechanisms for laser-induced polymer surface modification, with a significant contribution of the laser foaming mechanism. Prospective applications of the laser-foamed hydrogel matrices in biomolecule immobilization are suggested.

  19. Super-hydrophilic surfaces by photo-induced micro-folding

    Energy Technology Data Exchange (ETDEWEB)

    Bahners, Thomas, E-mail: bahners@dtnw.de [Deutsches Textilforschungszentrum Nord-West e.V., Adlerstr. 1, 47798 Krefeld (Germany); Prager, Lutz; Kriehn, Stefanie [Leibniz-Institut fuer Oberflaechenmodifizierung e.V., Permoserstr. 15, 04318 Leipzig (Germany); Gutmann, Jochen S. [Deutsches Textilforschungszentrum Nord-West e.V., Adlerstr. 1, 47798 Krefeld (Germany); Universitaet Duisburg-Essen, Physikalische Chemie, Universitaetsstr. 5, 45141 Essen (Germany)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Totally wetting surfaces were prepared from UV cured acrylate layers. Black-Right-Pointing-Pointer The process of photo-induced micro-folding was employed for large area treatments. Black-Right-Pointing-Pointer Up to roughness factors of 1.2, the spreading followed a Wenzel-type behavior. Black-Right-Pointing-Pointer Spreading on surfaces of more pronounced roughness was governed by surface features. - Abstract: A two-step UV curing process of thin acrylate layers was employed to prepare micro-rough top-coats on polymer film. The concept of the process (known as 'photonic micro-folding') is to apply a thin acrylate layer on a substrate and cure the layer by subsequent exposures to VUV and broad band UV radiation. The first curing step leads to curing of the skin of the acrylate layer alone, which induces shrinkage and folding. This structure is fixed in the second curing step which affects the bulk of the acrylate layer. The process is easily applied to any substrate and large areas. By using hydrophilic hydroxypropylacrylate and polyethylenglycolmonoacrylate as the main components of the applied acrylate, perfectly wetting - super-hydrophilic - surfaces were obtained. This basically is in accordance with the concept of Wenzel's equation which relates the apparent contact angle to a roughness factor r given by the ratio of true and projected surface area. The analysis of the data of this work, however, shows that the spreading of a droplet on surfaces with r > 1.2 is governed by geometric effects such as blockage by the surface features and cannot by described by Wenzel's equation.

  20. A water-like model under confinement for hydrophobic and hydrophilic particle-plate interaction potentials

    OpenAIRE

    Krott, Leandro B.; BARBOSA, Marcia C.

    2013-01-01

    Molecular dynamic simulations were employed to study a water-like model confined between hydrophobic and hydrophilic plates. The phase behavior of this system is obtained for different distances between the plates and particle-plate potentials. For both hydrophobic and hydrophilic walls there are the formation of layers. Crystallization occurs at lower temperature at the contact layer than at the middle layer. In addition, the melting temperature decreases as the plates become more hydrophobi...

  1. Spatially selective modification of PLLA surface: From hydrophobic to hydrophilic or to repellent

    Science.gov (United States)

    Bastekova, Kristina; Guselnikova, Olga; Postnikov, Pavel; Elashnikov, Roman; Kunes, Martin; Kolska, Zdenka; Švorčík, Vaclav; Lyutakov, Oleksiy

    2017-03-01

    A universal approach to controlled surface modification of polylactic acid (PLLA) films using diazonium chemistry was proposed. The multistep procedure includes surface activation of PLLA by argon plasma treatment and chemical activation of arenediazonium tosylates by NaBH4. The surface of PLLA film was grafted with different functional organic groups (OFGs), changing the PLLA surface properties (wettability, morphology, zeta potential, chemical composition, and mechanical response). Three approaches of OFG grafting were examined: (i) plasma treatment following by PLLA immersion into diazonium salt aqueous solution; (ii) grafting of PLLA surface through the reaction with chemically created aryl radicals; (iii) mutual combination of both methods The best results were achieved in the last case, where the previous plasma treatment was combined with further reaction of PLLA surface with generated aryl radicals. Using this method PLLA surface was successfully grafted with amino, carboxyl, aliphatic and fluorinated OFGs. Further investigation of surface properties from potential biological and medical points of view was performed using zeta potential, biodegradation and biofouling tests. It was shown that proposed technique allows preparation of biorepellent or bioabsorptive surfaces, tuning of PLLA biodegradation rate and nanomechanical properties, as well as the introduction of inverse properties (such as hydrophilic and hydrophobic) on both sides of PLLA films.

  2. Adsorption of non-ionic surfactants on hydrophobic and hydrophilic carbon surfaces.

    Science.gov (United States)

    Soria-Sánchez, M; Maroto-Valiente, A; Guerrero-Ruiz, A; Nevskaia, D M

    2010-03-01

    The adsorption from aqueous solutions of a series of non-ionic surfactants (TX-114, TX-100, TX-165 and TX-305, where the ethoxylation degree is increasing in the series) on a non-microporous carbon surface, that is a high surface area graphite (GT), and on a mainly microporous activated carbon (NT) has been comparatively studied. Also the initially hydrophobic GT and NT surfaces have been modified by oxidation treatments in order to achieve partially hydrophilic carbon materials (GTox and NTox samples). The adsorption results reveal that for GT sample below the critical micellar concentrations (cmc) of surfactants practically the whole surface is covered by monomers. For NT there are steric hindrance limitations, so the surfactant molecules are adsorbed only on micropores of sizes larger than 8A. When oxygen surface groups are introduced on the carbonaceous surfaces, the adsorption behaviour is again different for both materials. Thus, for GTox the adsorbed amounts below the cmc decrease probably due to withdrawal effect of the oxygen surface groups. On the contrary, the adsorbed amounts above the cmc slightly increase with regard to bare graphite, possibly due to an improved formation of micelles. In the case of NTox the adsorbed uptakes below and above cmc increase remarkably in comparison with NT sample, which can be explained by some specific interactions of the surfactants molecules with oxygen surface groups inside the micropores.

  3. Microemulsions as model fluids for enhanced oil recovery: dynamics adjacent to planar hydrophilic walls

    Directory of Open Access Journals (Sweden)

    Mattauch S.

    2012-10-01

    Full Text Available After the dynamics of microemulsions adjacent to a planar hydrophilic wall have been characterized using grazing incidence neutron spin echo spectroscopy, the model of Seifert was employed to explain the discovered acceleration for the surface near lamellar ordered membranes. Reflections of hydrodynamic waves by the wall – or the volume conservation between the membrane and the wall – explain faster relaxations and, therefore, a lubrication effect that is important for flow fields in narrow pores. The whole scenery is now spectated by using different scenarios of a bicontinuous microemulsion exposed to clay particles and of a lamellar microemulsion adjacent to a planar wall. The Seifert concept could successfully be transferred to the new problems.

  4. Comparative sessile drop and dip pen nanolithography investigation for various hydrophilic ink/surface systems.

    Science.gov (United States)

    Yadav, Pradeep K; Lemoine, Patrick

    2012-01-01

    We present a dip pen nanolithography study of various hydrophilic ink/surface systems with application in the field of biosensors and novel nano-materials. The inking process was investigated by studying a number of inks, such as Deoxyribonucleic acid (DNA), Bovine serum albumin (BSA), Streptavidin, 16-mercaptohexadecanoic acid (MHA) and a 20 nm nanosphere (NS) polystyrene solution onto a range of substrates, namely glass, silicon, gold and tetrahedral amorphous carbon (taC). In the majority of cases, this resulted in patterns with sub-100 nm line widths and dot diameters. Importantly, contact angle measurements in the microl range showed a decrease of contact angle with drop volume, interpreted as a line tension effect. The significance of this to the nanoscale wetting behaviour is discussed. The effect of dwell time and writing speed indicates that the inking process is not solely defined by surface diffusion but also influenced by the ink dissolution rate from the tip.

  5. Numerical analysis of the movement of an initially hemispherical droplet hydrophilic/hydrophobic surface

    Energy Technology Data Exchange (ETDEWEB)

    Myong, Hyong Kook; Kwon, Young Hoo [Dept. of Mechanical Engineering, Kookmin University, Seoul (Korea, Republic of)

    2015-03-15

    Fluid transport is a key issue in the development of microfluidic systems. Recently, Myong (2014) has proposed a new concept for droplet transport without external power sources and numerically validated the results for a hypothetical 2D, initially having a hemicylindrical droplet. In this paper, the movement of an actual water droplet, initially having a 3D hemispherical shape, on horizontal hydrophilic/hydrophobic surfaces is simulated using a commercial computational fluid dynamics (CFD) package, Fluent, with VOF (volume of fluid) method. The results are compared with the 2D analysis of Myong (2014), and the transport mechanism for the actual water droplet is examined based on the numerical results of the time evolution of the droplet shape, as well as the total kinetic, gravitational, surface free and pressure energies inside the droplet.

  6. A New Concept to Transport a Droplet on Horizontal Hydrophilic/Hydrophobic Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Myong, Hyon Kook [Kookmin Univ., Seoul (Korea, Republic of)

    2014-03-15

    A fluid transport technique is a key issue for the development of microfluidic systems. In this paper, a new concept for transporting a droplet without external power sources is proposed and verified numerically. The proposed device is a heterogeneous surface which has both hydrophilic and hydrophobic horizontal surfaces. The numerical simulation to demonstrate the new concept is conducted by an in-house solution code (PowerCFD) which employs an unstructured cell-centered method based on a conservative pressure-based finite-volume method with interface capturing method (CICSAM) in a volume of fluid (VOF) scheme for phase interface capturing. It is found that the proposed concept for droplet transport shows superior performance for droplet transport in microfluidic systems.

  7. Transport mechanism of an initially spherical droplet on a combined hydrophilic/hydrophobic surface

    Energy Technology Data Exchange (ETDEWEB)

    Myong, Hyon Kook; Kwon, Young Hoo [Dept. of Mechanical Engineering, Kookmin University, Seoul (Korea, Republic of)

    2015-11-15

    Fluid transport is a key issue in the development of microfluidic systems. Recently, Myong (2014) has proposed a new concept for droplet transport without external power sources, and numerically validated the results for a hypothetical 2D shape, initially having a hemicylindrical droplet shape. Myong and Kwon (2015) have also examined the transport mechanism for an actual water droplet, initially having a 3D hemispherical shape, on a horizontal hydrophilic/hydrophobic surface, based on the numerical results of the time evolution of the droplet shape, as well as the total kinetic, gravitational, pressure and surface free energies inside the droplet. In this study, a 3D numerical analysis of an initially spherical droplet is carried out to establish a new concept for droplet transport. Further, the transport mechanism of an actual water droplet is examined in detail from the viewpoint of the capillarity force imbalance through the numerical results of droplet shape and various energies inside the droplet.

  8. On the slip number choice in computations of liquid droplet impinging on a hydrophilic surface

    CERN Document Server

    Ganesan, Sashikumaar

    2015-01-01

    A mesh-dependent relation for the slip number in the Navier-slip with friction boundary condition for computations of impinging droplets is proposed. The relation is obtained as a function of the Reynolds number, the Weber number and the mesh size. The proposed relation is validated for several test cases by comparing the numerically obtained wetting diameter with the experimental results. Further, the computationally obtained maximum wetting diameter using the proposed slip relation is verified with the theoretical predictions. The relative error between the computationally obtained maximum wetting diameter and the theoretical predictions is less than 10\\% for impinging droplet on a hydrophilic surface, and the error increases in the case of hydrophobic surface.

  9. Surface modification of CNTs and enhanced photocatalytic activity of TiO{sub 2} coated on hydrophilically modified CNTs

    Energy Technology Data Exchange (ETDEWEB)

    Yang Hanpei, E-mail: yanghanpei@hhu.edu.cn [Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098 (China); Wu Sha; Duan Yunping; Fu Xiaofei; Wu Junming [Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, Ministry of Education, College of Environment, Hohai University, Nanjing 210098 (China)

    2012-01-15

    A new method to enhance photocatalytic performance of TiO{sub 2} by dispersing it onto hydrophilically surface modified carbon nanotubes is reported. The hydrophilically surface functionalized CNTs and as prepared composite CNTs-TiO{sub 2} photocatalysts were characterized using FT-IR, XPS, XRD, BET adsorption analysis and TEM. The composite samples were evaluated for their photocatalytic activity toward the degradation of methyl orange in aqueous solution under both UV and visible light irradiation. The results indicated that the hydrophilic functional groups were grafted covalently on the surface of CNTs successfully, and the functionalized CNTs exhibit higher BET specific surface area and aquatic solubility. The improved photocatalytic activity of CNTs-TiO{sub 2} was mainly attributed to the high dispersion of TiO{sub 2} on CNTs and the intimate contact between TiO{sub 2} and CNTs resulting in dense heterojunctions at the interface of TiO{sub 2} and CNTs.

  10. Effects of fluid flow on elution of hydrophilic modifier from dialysis membrane surfaces.

    Science.gov (United States)

    Matsuda, Masato; Sato, Mika; Sakata, Hiroki; Ogawa, Takahisa; Yamamoto, Ken-ichiro; Yakushiji, Taiji; Fukuda, Makoto; Miyasaka, Takehiro; Sakai, Kiyotaka

    2008-01-01

    When uremic blood flows through dialyzers during hemodialysis, dialysis membrane surfaces are exposed to shear stress and internal filtration, which may affect the surface characteristics of the dialysis membranes. In the present study, we evaluated changes in the characteristics of membrane surfaces caused by shear stress and internal filtration using blood substitutes: water purified by reverse osmosis and 6.7 wt% dextran70 solution. We focused on the levels of a hydrophilic modifier, polyvinylpyrrolidone (PVP), on the membrane surface measured by attenuated total reflectance Fourier transform infrared spectroscopy. Experiments involving 4 h dialysis, 0-144 h shear-stress loading, and 4 h dead-end filtration were performed using polyester-polymer alloy (PEPA) and polysulfone (PS) membranes. After the dialysis experiments with accompanying internal filtration, average PVP retention on the PEPA membrane surface was 93.7% in all areas, whereas that on the PS membrane surface was 98.9% in all areas. After the shear-stress loading experiments, PVP retention on the PEPA membrane surface decreased as shear-stress loading time and the magnitude of shear stress increased. However, with the PS membrane, PVP retention scarcely changed. After the dead-end filtration experiments, PVP retention decreased in all areas for both PEPA and PS membranes, but PVP retention on the PEPA membrane surface was lower than that on the PS membrane surface. PVP on the PEPA membrane surface was eluted by both shear stress and internal filtration, while that on the PS membrane surface was eluted only by internal filtration.

  11. Effect of wettability and surface roughness on ice-adhesion strength of hydrophilic, hydrophobic and superhydrophobic surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bharathidasan, T. [Surface Engineering Division, CSIR- National Aerospace Laboratories, Bangalore 560017 (India); Kumar, S. Vijay; Bobji, M.S. [Department of Mechanical Engineering, Indian Institute of Science, Bangalore 560003 (India); Chakradhar, R.P.S. [Surface Engineering Division, CSIR- National Aerospace Laboratories, Bangalore 560017 (India); Basu, Bharathibai J., E-mail: bharathijbasu@gmail.com [Surface Engineering Division, CSIR- National Aerospace Laboratories, Bangalore 560017 (India)

    2014-09-30

    Highlights: • Anti-icing property is related to wettability and surface roughness. • Silicone based hydrophobic coating showed excellent ice-adhesion strength. • Superhydrophobic surfaces displayed poor anti-icing property. - Abstract: The anti-icing properties of hydrophilic, hydrophobic and superhydrophobic surfaces/coatings were evaluated using a custom-built apparatus based on zero-degree cone test method. The ice-adhesion reduction factor (ARF) of these coatings has been evaluated using bare aluminium alloy as a reference. The wettability of the surfaces was evaluated by measuring water contact angle (WCA) and sliding angle. It was found that the ice-adhesion strength (τ) on silicone based hydrophobic surfaces was ∼ 43 times lower than compared to bare polished aluminium alloy indicating excellent anti-icing property of these coatings. Superhydrophobic coatings displayed poor anti-icing property in spite of their high water repellence. Field Emission Scanning Electron Microscope reveal that Silicone based hydrophobic coatings exhibited smooth surface whereas the superhydrophobic coatings had a rough surface consisting of microscale bumps and protrusions superimposed with nanospheres. Both surface roughness and surface energy play a major role on the ice-adhesion strength of the coatings. The 3D surface roughness profiles of the coatings also indicated the same trend of roughness. An attempt is made to correlate the observed ice-adhesion strength of different surfaces with their wettability and surface roughness.

  12. Surface morphological modification of crosslinked hydrophilic co-polymers by nanosecond pulsed laser irradiation

    Science.gov (United States)

    Primo, Gastón A.; Alvarez Igarzabal, Cecilia I.; Pino, Gustavo A.; Ferrero, Juan C.; Rossa, Maximiliano

    2016-04-01

    This work reports an investigation of the surface modifications induced by irradiation with nanosecond laser pulses of ultraviolet and visible wavelengths on crosslinked hydrophilic co-polymeric materials, which have been functionalized with 1-vinylimidazole as a co-monomer. A comparison is made between hydrogels differing in the base co-monomer (N,N-dimethylaminoethyl methacrylate and N-[3-(dimethylamino)propyl] methacrylamide) and in hydration state (both swollen and dried states). Formation of craters is the dominant morphological change observed by ablation in the visible at 532 nm, whereas additional, less aggressive surface modifications, chiefly microfoams and roughness, are developed in the ultraviolet at 266 nm. At both irradiation wavelengths, threshold values of the incident laser fluence for the observation of the various surface modifications are determined under single-pulse laser irradiation conditions. It is shown that multiple-pulse irradiation at 266 nm with a limited number of laser shots can be used alternatively for generating a regular microfoam layer at the surface of dried hydrogels based on N,N-dimethylaminoethyl methacrylate. The observations are rationalized on the basis of currently accepted mechanisms for laser-induced polymer surface modification, with a significant contribution of the laser foaming mechanism. Prospective applications of the laser-foamed hydrogel matrices in biomolecule immobilization are suggested.

  13. Creation of hydrophilic nitric oxide releasing polymers via plasma surface modification.

    Science.gov (United States)

    Pegalajar-Jurado, A; Joslin, J M; Hawker, M J; Reynolds, M M; Fisher, E R

    2014-08-13

    Herein, we describe the surface modification of an S-nitrosated polymer derivative via H2O plasma treatment, resulting in polymer coatings that maintained their nitric oxide (NO) releasing capabilities, but exhibited dramatic changes in surface wettability. The poly(lactic-co-glycolic acid)-based hydrophobic polymer was nitrosated to achieve a material capable of releasing the therapeutic agent NO. The NO-loaded films were subjected to low-temperature H2O plasma treatments, where the treatment power (20-50 W) and time (1-5 min) were varied. The plasma treated polymer films were superhydrophilic (water droplet spread completely in plasma-treated materials; however, they still result in physiologically relevant NO fluxes. XPS, SEM-EDS, and ATR-IR characterization suggests the plasma treatment resulted in polymer rearrangement and implantation of hydroxyl and carbonyl functional groups. Plasma treated samples maintained both hydrophilic surface properties and NO release profiles after storage at -18 °C for at least 10 days, demonstrating the surface modification and NO release capabilities are stable over time. The ability to tune polymer surface properties while maintaining bulk properties and NO release properties, and the stability of those properties under refrigerated conditions, represents a unique approach toward creating enhanced therapeutic biopolymers.

  14. Evaporative properties and pinning strength of laser-ablated, hydrophilic sites on lotus-leaf-like, nanostructured surfaces.

    Science.gov (United States)

    McLauchlin, Melissa L; Yang, Dongqing; Aella, P; Garcia, Antonio A; Picraux, S T; Hayes, Mark A

    2007-04-24

    Wetting, evaporative, and pinning strength properties of hydrophilic sites on superhydrophobic, nanostructured surfaces were examined. Understanding these properties is important for surface characterization and designing features in self-cleaning, lotus-leaf-like surfaces. Laser-ablated, hydrophilic spots between 250 mum and 2 mm in diameter were prepared on silicon nanowire (NW) superhydrophobic surfaces. For larger circumference pinning sites, initial contact angle measurements resemble the contact angle of the surface within the pinning site: 65-69 degrees . As the drop volume is increased, the contact angles approach the contact angle of the NW surface without pinning sites: 171-176 degrees . The behavior of water droplets on the pinning sites is governed by how much of the water droplet is being influenced by the superhydrophobic NW surfaces versus the hydrophilic areas. During the evaporation of sinapic acid solution, drops are pinned by the spots except for the smaller circumference sites. Pinning strengths of the hydrophilic sites are a linear function of the pinning spot circumference. Protein samples prepared and deposited on the pinning sites for analysis by matrix-assisted laser desorption ionization indicate an improvement in sensitivity from that of a standard plate analysis by a factor of 5.

  15. A facile strategy for the fabrication of a bioinspired hydrophilic-superhydrophobic patterned surface for highly efficient fog-harvesting

    KAUST Repository

    Wang, Yuchao

    2015-08-10

    Fog water collection represents a meaningful effort in the places where regular water sources, including surface water and ground water, are scarce. Inspired by the amazing fog water collection capability of Stenocara beetles in the Namib Desert and based on the recent work in biomimetic water collection, this work reported a facile, easy-to-operate, and low-cost method for the fabrication of hydrophilic-superhydrophobic patterned hybrid surface toward highly efficient fog water collection. The essence of the method is incorporating a (super)hydrophobically modified metal-based gauze onto the surface of a hydrophilic polystyrene (PS) flat sheet by a simple lab oven-based thermal pressing procedure. The produced hybrid patterned surfaces consisted of PS patches sitting within the holes of the metal gauzes. The method allows for an easy control over the pattern dimension (e.g., patch size) by varying gauze mesh size and thermal pressing temperature, which is then translated to an easy optimization of the ultimate fog water collection efficiency. Given the low-cost and wide availability of both PS and metal gauze, this method has a great potential for scaling-up. The results showed that the hydrophilic-superhydrophobic patterned hybrid surfaces with a similar pattern size to Stenocara beetles’s back pattern produced significantly higher fog collection efficiency than the uniformly (super)hydrophilic or (super)hydrophobic surfaces. This work contributes to general effort in fabricating wettability patterned surfaces and to atmospheric water collection for direct portal use.

  16. AFM study of forces between silicon oil and hydrophobic-hydrophilic surfaces in aqueous solutions.

    Science.gov (United States)

    Zbik, Marek S; Frost, Ray L

    2010-09-15

    An investigation has been made of the interactions between silicone oil and various solid substrates immersed in aqueous solutions. Measurements were made using an atomic force microscope (AFM) using the colloid-probe method. The silicone oil drop is simulated by coating a small silica sphere with the oil, and measuring the force as this coated sphere is brought close to contact with a flat solid surface. It is found that the silicone oil surface is negatively charged, which causes a double-layer repulsion between the oil drop and another negatively charged surface such as mica. With hydrophilic solids, this repulsion is strong enough to prevent attachment of the drop to the solid. However, with hydrophobic surfaces there is an additional attractive force which overcomes the double-layer repulsion, and the silicone oil drop attaches to the solid. There is circumstantial evidence that linear and nonlinear effect take part in force results from compression of the silicone oil film coated on the glass sphere.

  17. A smart dynamic self-induced orientable multiple size nano-roughness with amphiphilic feature as a stain-repellent hydrophilic surface.

    Science.gov (United States)

    Dastjerdi, Roya; Montazer, Majid; Stegmaier, Thomas; Moghadam, M B

    2012-03-01

    Recently developing bioinspired super-hydrophobic surfaces to achieve self-cleaning properties has been driving numerous researches. However, hydrophilicity is one of the most important features of garment comfort. Therefore, accomplishing self-cleaning and stain repellency on hydrophilic surfaces would be a high topic of interest. This research is concerned with wettability mechanism; static and dynamic study of contact angle through water droplet absorption on the multiple scale nano-roughness covered by different weight ratio of oppositely charged inorganic nanoparticles and amino-functionalized polysiloxane. The results revealed that the second layer of the resin formed on the surface can show an amphiphilic hybrid block copolymer-like feature whose dual action can be intensified during water droplet absorption by the created multiple size nano-roughness. This unique structure can create a stain repellent but hydrophilic surface with exceptional advantages. The mechanism has been deeply discussed according to the evidence on droplet edge interfacial energy changes as a driving force to overcome meta-stable Cassie state on the multiple size nano-roughness with amphiphilic feature. A lotus-like nano-roughness has been also observed on the SEM micrographs. Based on a statistically approached experimental design, the effect of variant factors on droplet absorption time, static, advancing, receding contact angles and self-cleaning properties has been mathematically modeled according to the response surface methodology (RSM).

  18. Osteoblastic and osteoclastic differentiation on SLA and hydrophilic modified SLA titanium surfaces.

    Science.gov (United States)

    Bang, Sung-Moon; Moon, Ho-Jin; Kwon, Yong-Dae; Yoo, Ji-Yeon; Pae, Ahran; Kwon, Il Keun

    2014-07-01

    We evaluated the activities of both osteoblastic and osteoclastic differentiation on sandblasted/acid etched (SLA), hydrophilic SLA surfaces (modSLA) and pretreatment titanium (PT). The osteoblastic differentiation was evaluated by alkaline phosphatase analysis and Alizarin Red S staining, and the expression of bone-related proteins, alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2), osteopontin (OPN), and osteocalcin (OCN), was investigated by reverse transcriptase-polymerase chain reaction (RT-PCR). Primary mice monocytes were expanded and differentiated in the presence of macrophage-colony stimulating factor (M-CSF), and osteoclastic differentiation was evaluated by actin ring formation assay and tartrate-resistant acid phosphatase (TRAP) activity assay. Real-time PCR tests were performed to investigate the expression of gene mRNA expression levels in osteoclast cells. Differentiation of osteoblasts in the Alizarin Red S test staining and ALP assay was significantly increased in the modSLA surface. The preceding results were supported by the result of RT-PCR for the expression of Runx2, OPN, and OCN. As for osteoclastic activity, differentiated osteoclasts rarely existed on the SLA and modSLA surface with actin ring. The results of real-time PCR and TRAP activity supported the preceding results. It may be concluded that the modSLA surface promotes osteogenic effect and prevents osteoclastic differentiation. Promotion of osteoblastic proliferation after a short-term cell culture might be responsible for stimulated bone regeneration implying that early loading may be possible. Also, the anti-osteoclastic effect of the modSLA surface may contribute to maintenance of the marginal bone level of dental implants, implying long-term stability would be provided by this surface technology. The modSLA surface may not only make early loading possible but possibly reduce marginal bone loss during the maintenance phase. © 2013 John Wiley & Sons A

  19. Conversion of an electrospun nanofibrous cellulose acetate mat from a super-hydrophilic to super-hydrophobic surface

    Science.gov (United States)

    Ding, Bin; Li, Chunrong; Hotta, Yoshio; Kim, Jinho; Kuwaki, Oriha; Shiratori, Seimei

    2006-09-01

    We report a new approach to convert an electrospun nanofibrous cellulose acetate mat surface from super-hydrophilic to super-hydrophobic. Super-hydrophilic cellulose acetate nanofibrous mats can be obtained by electrospinning hydrophilic cellulose acetate. The surface properties of the fibrous mats were modified from super-hydrophilic to super-hydrophobic with a simple sol-gel coating of decyltrimethoxysilane (DTMS) and tetraethyl orthosilicate (TEOS). The resultant samples were characterized by field emission scanning electron microscopy (FE-SEM), x-ray photoelectron spectroscopy (XPS), water contact angle, Brunauer-Emmett-Teller (BET) surface area, atomic force microscopy (AFM), and UV-visible measurements. The results of FE-SEM and XPS showed that the sol-gel (I) films were formed on the rough fibrous mats only after immersion in sol-gel. After the sol-gel (I) coating, the cellulose acetate fibrous mats formed in both 8 and 10 wt% cellulose acetate solutions showed the super-hydrophobic surface property. Additionally, the average sol-gel film thickness coated on 10 wt% cellulose acetate fibrous mats was calculated to be 80 nm. The super-hydrophobicity of fibrous mats was attributed to the combined effects of the high surface roughness of the electrospun nanofibrous mats and the hydrophobic DTMS sol-gel coating. Additionally, hydrophobic sol-gel nanofilms were found to be transparent according to UV-visible measurements.

  20. Model of waterlike fluid under confinement for hydrophobic and hydrophilic particle-plate interaction potentials.

    Science.gov (United States)

    Krott, Leandro B; Barbosa, Marcia C

    2014-01-01

    Molecular dynamic simulations were employed to study a waterlike model confined between hydrophobic and hydrophilic plates. The phase behavior of this system is obtained for different distances between the plates and particle-plate potentials. For both hydrophobic and hydrophilic walls, there are the formation of layers. Crystallization occurs at lower temperature at the contact layer than at the middle layer. In addition, the melting temperature decreases as the plates become more hydrophobic. Similarly, the temperatures of maximum density and extremum diffusivity decrease with hydrophobicity.

  1. Hydrophilic property of 316L stainless steel after treatment by atmospheric pressure corona streamer plasma using surface-sensitive analyses

    Energy Technology Data Exchange (ETDEWEB)

    Al-Hamarneh, Ibrahim, E-mail: hamarnehibrahim@yahoo.com [Department of Physics, Faculty of Science, Al-Balqa Applied University, Salt 19117 (Jordan); Pedrow, Patrick [School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA 99164 (United States); Eskhan, Asma; Abu-Lail, Nehal [Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA 99164 (United States)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer Surface hydrophilic property of surgical-grade 316L stainless steel was enhanced by Ar-O{sub 2} corona streamer plasma treatment. Black-Right-Pointing-Pointer Hydrophilicity, surface morphology, roughness, and chemical composition before and after plasma treatment were evaluated. Black-Right-Pointing-Pointer Contact angle measurements and surface-sensitive analyses techniques, including XPS and AFM, were carried out. Black-Right-Pointing-Pointer Optimum plasma treatment conditions of the SS 316L surface were determined. - Abstract: Surgical-grade 316L stainless steel (SS 316L) had its surface hydrophilic property enhanced by processing in a corona streamer plasma reactor using O{sub 2} gas mixed with Ar at atmospheric pressure. Reactor excitation was 60 Hz ac high-voltage (0-10 kV{sub RMS}) applied to a multi-needle-to-grounded screen electrode configuration. The treated surface was characterized with a contact angle tester. Surface free energy (SFE) for the treated stainless steel increased measurably compared to the untreated surface. The Ar-O{sub 2} plasma was more effective in enhancing the SFE than Ar-only plasma. Optimum conditions for the plasma treatment system used in this study were obtained. X-ray photoelectron spectroscopy (XPS) characterization of the chemical composition of the treated surfaces confirms the existence of new oxygen-containing functional groups contributing to the change in the hydrophilic nature of the surface. These new functional groups were generated by surface reactions caused by reactive oxidation of substrate species. Atomic force microscopy (AFM) images were generated to investigate morphological and roughness changes on the plasma treated surfaces. The aging effect in air after treatment was also studied.

  2. Interactions between nano-TiO{sub 2} and the oral cavity: Impact of nanomaterial surface hydrophilicity/hydrophobicity

    Energy Technology Data Exchange (ETDEWEB)

    Teubl, Birgit J.; Schimpel, Christa [Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology, University of Graz, 8010 (Austria); Leitinger, Gerd [Institute of Cell Biology, Histology and Embryology, Research Unit Electron Microscopic Techniques, Medical University of Graz, 8010 (Austria); Center for Medical Research, Medical University of Graz, 8010 (Austria); BioTechMed, Graz 8010 (Austria); Bauer, Bettina [Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology, University of Graz, 8010 (Austria); Fröhlich, Eleonore [Center for Medical Research, Medical University of Graz, 8010 (Austria); BioTechMed, Graz 8010 (Austria); Zimmer, Andreas [Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology, University of Graz, 8010 (Austria); BioTechMed, Graz 8010 (Austria); Roblegg, Eva, E-mail: eva.roblegg@uni-graz.at [Institute of Pharmaceutical Sciences, Department of Pharmaceutical Technology, University of Graz, 8010 (Austria); BioTechMed, Graz 8010 (Austria)

    2015-04-09

    Highlights: • Hydrophilic as well as hydrophobic TiO{sub 2} NPs agglomerated under oral physiological conditions. • Particles penetrated the upper and lower buccal epithelium, independent on the degree of hydrophilicity. • Most of the hydrophobic particles were found in vesicular structures, while hydrophilic particles were freely distributed in the cytoplasm. • Hydrophilic particles had a higher potential to trigger toxic effects (e.g., ROS) than hydrophobic particles. - Abstract: Titanium dioxide (TiO{sub 2}) nanoparticles are available in a variety of oral applications, such as food additives and cosmetic products. Thus, questions about their potential impact on the oro-gastrointestinal route rise. The oral cavity represents the first portal of entry and is known to rapidly interact with nanoparticles. Surface charge and size contribute actively to the particle–cell interactions, but the influence of surface hydrophilicity/hydrophobicity has never been shown before. This study addresses the biological impact of hydrophilic (NM 103, rutile, 20 nm) and hydrophobic (NM 104, rutile, 20 nm) TiO{sub 2} particles within the buccal mucosa. Particle characterization was addressed with dynamic light scattering and laser diffraction. Despite a high agglomeration tendency, 10% of the particles/agglomerates were present in the nanosized range and penetrated into the mucosa, independent of the surface properties. However, significant differences were observed in intracellular particle localization. NM 104 particles were found freely distributed in the cytoplasm, whereas their hydrophobic counterparts were engulfed in vesicular structures. Although cell viability/membrane integrity was not affected negatively, screening assays demonstrated that NM 104 particles showed a higher potential to decrease the physiological mitochondrial membrane potential than NM 103, resulting in a pronounced generation of reactive oxygen species.

  3. On the stability of the polymer brushes formed by adsorption of Ionomer Complexes on hydrophilic and hydrophobic surfaces

    NARCIS (Netherlands)

    Brzozowska, A. M.; Spruijt, E.; de Keizer, A.; Stuart, M. A. Cohen; Norde, W.

    2011-01-01

    We have studied the effect of normal forces and shear forces on the stability and functionality of a polymer brush layer formed upon adsorption of polymeric micelles on hydrophilic and hydrophobic surfaces. The micelles consist of oppositely charged polyelectrolyte blocks (poly(acrylic acid) and pol

  4. Polyethyleneimine High-Energy Hydrophilic Surface Interfacial Treatment toward Efficient and Stable Perovskite Solar Cells.

    Science.gov (United States)

    Li, Pengwei; Liang, Chao; Zhang, Yiqiang; Li, Fengyu; Song, Yanlin; Shao, Guosheng

    2016-11-30

    The interfacial contact is critical for the performance of perovskite solar cells (PSCs), leading to dense perovskite thin films and efficient charge transport. In this contribution, an effective interfacial treatment solution using polyethyleneimine (PEI) was developed to improve the performance and stability of PSCs. Inserting PEI between the s-VOx and perovskite layers can produce a high-energy hydrophilic surface to facilitate the formation of a high-quality perovskite layer by the solution method. Accordingly, the surface coverage of perovskite film on the s-VOx layer increased from 80% to 95%, and the PCE of the device improved from 12.06% (with an average of 10.16%) to 14.4% (with an average value of 12.8%) under an irradiance of 100 mW cm(-2) AM 1.5G sunlight. More importantly, the stability of PSCs was further improved after adding another PEI layer between the electron transport layer and LiF/Al layer, less than 10% decay in efficiency during a 10-days observation. Since all layers of the PSCs were fabricated at low temperature (<150 °C), these PEI-treated PSCs based on the amorphous VOx layer have the potential to contribute significantly toward the development of efficient and stable solar cells on flexible substrates.

  5. Development of high performance nano-porous polyethersulfone ultrafiltration membranes with hydrophilic surface and superior antifouling properties

    Energy Technology Data Exchange (ETDEWEB)

    Rahimpour, Ahmad, E-mail: ahmadrahimpour@yahoo.com [Nanobiotechnology Research Laboratory, Faculty of Chemical Engineering, Babol University of Technology, Babol (Iran, Islamic Republic of); Madaeni, Sayed Siavash [Membrane Research Center, Department of Chemical Engineering, Razi University, Kermanshah (Iran, Islamic Republic of); Jahanshahi, Mohsen [Nanobiotechnology Research Laboratory, Faculty of Chemical Engineering, Babol University of Technology, Babol (Iran, Islamic Republic of); Mansourpanah, Yaghoub [Department of Chemistry, Faculty of Science, Lorestan University, Khorramabad (Iran, Islamic Republic of); Mortazavian, Narmin [Nanobiotechnology Research Laboratory, Faculty of Chemical Engineering, Babol University of Technology, Babol (Iran, Islamic Republic of)

    2009-08-30

    Hydrophilic nano-porous polyethersulfone ultrafiltration membranes were developed for milk concentration. The membranes were prepared from new dope solution containing polyethersulfone (PES)/polyvinylpirrolidone (PVP)/polyethyleneglycole (PEG)/cellulose acetate phthalate (CAP)/acrylic acid/Triton X-100 using phase inversion induced by immersion precipitation technique. This casting solution leads to formation of new hydrophilic membranes. The morphological studies were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). In addition, the hydrophilicity and performance of membranes were examined by contact angel measurements and cross-flow filtration (pure water flux, milk water permeation, protein rejection and antifouling measurements). The contact angle measurements indicate that a surface with superior hydrophilicity was obtained for PES membranes. Two concentrations of PES (16 and 14.4 wt.%) and two different non-solvents (pure water and mixtures of water and IPA) were used for preparation of membranes. The morphological studies showed that the higher concentration of PES and the presence of IPA in the gelation media results in formation of a membrane with a dense top and sub-layer with small pores on the surface. The pure water flux of membranes was decreased when higher polymer concentration and mixtures of water and IPA were employed for membrane formation. On the other hand, the milk water permeation and protein rejection were increased using mixtures of water and IPA as non-solvent. Furthermore, the fouling analysis of the membranes demonstrated that the membrane surface with fewer tendencies for fouling was obtained.

  6. Effect of low-concentration rhamnolipid on adsorption of Pseudomonas aeruginosa ATCC 9027 on hydrophilic and hydrophobic surfaces.

    Science.gov (United States)

    Zhong, Hua; Jiang, Yongbing; Zeng, Guangming; Liu, Zhifeng; Liu, Liuxia; Liu, Yang; Yang, Xin; Lai, Mingyong; He, Yibin

    2015-03-21

    The effects of low-concentration monorhamnolipid (monoRL) on the adsorption of Pseudomonas aeruginosa ATCC 9027 grown on glucose or hexadecane to glass beads with hydrophobic or hydrophilic surfaces was investigated using batch adsorption experiments. Results showed that adsorption isotherms of the cells on both types of glass beads fitted the Freundlich equation better than the Langmuir equation. The Kf of the Freundlich equation for adsorption of hexadecane-grown cell to glass beads with hydrophobic surface was remarkably higher than that for adsorption of hexadecane-grown cell to glass beads with hydrophilic surface, or glucose-grown cell to glass beads with either hydrophilic or hydrophobic surface. Furthermore, it decreased with the increasing monoRL concentration. For both groups of cells, the zeta potential was close to each other and stable with the increase of monoRL concentration. The surface hydrophobicity of hexadecane-grown cells, however, was significantly higher than that of the glucose-grown cells and it decreased with the increase of monoRL concentration. The results indicate the importance of hydrophobic interaction on adsorption of bacterial cells to surfaces and monoRL plays a role in reducing the bacterial adsorption by affecting cell surface hydrophobicity.

  7. Nisin-activated hydrophobic and hydrophilic surfaces: assessment of peptide adsorption and antibacterial activity against some food pathogens.

    Science.gov (United States)

    Karam, Layal; Jama, Charafeddine; Mamede, Anne-Sophie; Boukla, Samir; Dhulster, Pascal; Chihib, Nour-Eddine

    2013-12-01

    An effective antimicrobial packaging or food contact surface should be able to kill or inhibit micro-organisms that cause food-borne illnesses. Setting up such systems, by nisin adsorption on hydrophilic and hydrophobic surfaces, is still a matter of debate. For this purpose, nisin was adsorbed on two types of low-density polyethylene: the hydrophobic native film and the hydrophilic acrylic acid-treated surface. The antibacterial activity was compared for those two films and it was highly dependent on the nature of the surface and the nisin-adsorbed amount. The hydrophilic surfaces presented higher antibacterial activity and higher amount of nisin than the hydrophobic surfaces. The effectiveness of the activated surfaces was assessed against Listeria innocua and the food pathogens Listeria monocytogenes, Bacillus cereus, and Staphylococcus aureus. S. aureus was more sensitive than the three other test bacteria toward both nisin-functionalized films. Simulation tests to mimic refrigerated temperature showed that the films were effective at 20 and 4 °C with no significant difference between the two temperatures after 30 min of exposure to culture media.

  8. Bacterial biofilms utilization of low concentrations of organic matter on hydrophile surfaces submerged in seawater

    Directory of Open Access Journals (Sweden)

    Aurelia Manuela Moldoveanu

    2011-12-01

    Full Text Available A series of experiments were designed to determine the effect and the metabolic rate utilization of various types of organic matter in low concentration by heterotrophic marine bacteria using as Henrici slide technique as culture method and “in vitro” static conditions in sterile containers in order to obtain bacterial biofilms on the hydrophile surface of glass. The bacteria attachment and biofilm formation was analyzed for a period from 2 hours to 72 hours in order to observe de first phase of biofilm formation in condition of seawater supplied  with organic matter and noninvasive optic microscopy analysis. The utilization of five different  types of organic substances (amino-acid mixture, yeast extract, tryptone, glucose and starch reveled that bacteria multiply and are otherwise physiologically active in this very dilute nutrient solutions of 0.1% and also the results revealed that the bacterial growth was considerable in the case of the substances like amino-acid mixture with a total density of 30.9∙103 cells/mm2  and tryptone with a total density of 28.85∙103 cells/mm2  comparable to the other types of organic matter used to supply the seawater

  9. Surface modification of commercial seawater reverse osmosis membranes by grafting of hydrophilic monomer blended with carboxylated multiwalled carbon nanotubes

    Science.gov (United States)

    Vatanpour, Vahid; Zoqi, Naser

    2017-02-01

    In this study, modification of commercial seawater reverse osmosis membranes was carried out with simultaneous use of surface grafting and nanoparticle incorporation. Membrane grafting with a hydrophilic acrylic acid monomer and thermal initiator was used to increase membrane surface hydrophilicity. The used nanomaterial was carboxylated multiwalled carbon nanotubes (MWCNTs), which were dispersed in the grafting solution and deposited on membrane surface to reduce fouling by creating polymer brushes and hydrodynamic resistance. Effectiveness of the grafting process (formation of graft layer on membrane surface) was proved by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses. Increase of membrane surface hydrophilicity was approved with contact angle test. First, the grafting was performed on the membrane surfaces with different monomer concentrations, various contact times and several membrane curing times (three variables for optimization). The modified membranes were tested by a cross-flow setup using saline solution for permeability and rejection tests, and bovine serum albumin (BSA) solution for fouling test. The results showed that the modified membranes with 0.75 M of monomer, 3 min contact time and 80 min curing time in an oven at 50 °C presented the highest flux and lowest rejection decline related to the commercial reverse osmosis membrane. In the next step, the optimum grafting condition was selected and the nanotubes with different weight percentages were dispersed in the acrylic acid monomer solution. The membrane containing 0.25 wt% COOH-MWCNTs showed the highest fouling resistance.

  10. Surface Hydrophilicity and Functional Group-Driven Iron(III) Hydroxide Nucleation on Organic-Coated Substrates in Aqueous Environments

    Science.gov (United States)

    Ray, J.; Lee, B.; Baltrusaitis, J.; Jun, Y.

    2012-12-01

    polyaspartate substrate and least in the presence of the quartz substrate. Based on contact angle measurements and surface characterization, we concluded that the degree of hydrophilicity may control heterogeneous nucleation. Differences in substrate surface energy and potential arrangements of functional groups at the substrate surface (-OH and -COOH) may also contribute to the observed trends. These results provide new information for elucidating the effects of polymeric organic substrate coatings on the size, volume, and location of nucleating iron hydroxides, which will help predict nanoparticle interactions in natural and engineered systems. While iron oxide nanoparticles have been extensively studied in aqueous systems, there are still few studies providing in situ hetero- and homogeneous nucleation in the presence of relevant environmental organic substrates, which can aid in modeling the fate and transport of nanoparticles and contaminants in aqueous systems.

  11. Are the interactions between recombinant prion proteins and polymeric surfaces related to the hydrophilic/hydrophobic balance?

    Science.gov (United States)

    Vrlinic, Tjasa; Debarnot, Dominique; Legeay, Gilbert; Coudreuse, Arnaud; El Moualij, Benaissa; Zorzi, Willy; Perret-Liaudet, Armand; Quadrio, Isabelle; Mozetic, Miran; Poncin-Epaillard, Fabienne

    2012-06-01

    New non-fouling tubes are developed and their influence on the adhesion of neuroproteins is studied. Recombinant prion proteins are considered as a single component representative of hydrophobic proteins. Samples are stored for 24 h at 4 °C in tubes coated with two different coatings: poly(N-isopropylacrylamide) as a hydrophilic surface and a plasma-fluorinated coating as a hydrophobic one. The protein adhesion is monitored by ELISA tests, XPS and confocal microscopy. It appears that the highest recovery of recombinant prion protein in the liquid phase is obtained with the hydrophilic surface while the hydrophobic character of the storage tube induces an important amount of biological loss. However, the recovery is not complete even for tubes coated with poly(N-isopropylacrylamide).

  12. Hydrophilic anthropogenic markers for quantification of wastewater contamination in ground- and surface waters.

    Science.gov (United States)

    Kahle, Maren; Buerge, Ignaz J; Müller, Markus D; Poiger, Thomas

    2009-12-01

    Hydrophilic, persistent markers are useful to detect, locate, and quantify contamination of natural waters with domestic wastewater. The present study focused on occurrence and fate of seven marker candidates including carbamazepine (CBZ), 10,11-dihydro-10,11-dihydroxycarbamazepine (DiOH-CBZ), primidone (PMD), crotamiton (CTMT), N-acetyl-4-aminoantipyrine (AAA), N-formyl-4-aminoantipyrine (FAA), and benzotriazole (BTri) in wastewater treatment plants (WWTPs), lakes, and groundwater. In WWTPs, concentrations from 0.14 microg/L to several micrograms per liter were observed for all substances, except CTMT, which was detected at lower concentrations. Loads determined in untreated and treated wastewater indicated that removal of the potential markers in WWTPs is negligible; only BTri was partly eliminated (average 33%). In lakes, five compounds, CBZ, DiOH-CBZ, FAA, AAA, and BTri, were consistently detected in concentrations of 2 to 70 ng/L, 3 to 150 ng/L, less than the limit of quantification to 30 ng/L, 2 to 80 ng/L, and 11 to 920 ng/L, respectively. Mean per capita loads in the outflows of the lakes suggested possible dissipation in surface waters, especially of AAA and FAA. Nevertheless, concentrations of CBZ, DiOH-CBZ, and BTri correlated with the actual anthropogenic burden of the lakes by domestic wastewater, indicating that these compounds are suitable for quantification of wastewater contamination in lakes. Marker candidates were also detected in a number of groundwater samples. Carbamazepine concentrations up to 42 ng/L were observed in aquifers with significant infiltration of river water, receiving considerable wastewater discharges from WWTPs. Concentration ratios between compounds indicated some elimination of BTri and DiOH-CBZ during subsurface passage or in groundwater, while CBZ and PMD appeared to be more stable and thus are promising wastewater markers for groundwater. The wastewater burden in groundwater, estimated with the markers CBZ and PMD

  13. Temporal Changes in Extracellular Polymeric Substances on Hydrophobic and Hydrophilic Membrane Surfaces in a Submerged Membrane Bioreactor

    KAUST Repository

    Matar, Gerald Kamil

    2016-03-02

    Membrane surface hydrophilic modification has always been considered to mitigating biofouling in membrane bioreactors (MBRs). Four hollow-fiber ultrafiltration membranes (pore sizes ∼0.1 μm) differing only in hydrophobic or hydrophilic surface characteristics were operated at a permeate flux of 10 L/m2.h in the same lab-scale MBR fed with synthetic wastewater. In addition, identical membrane modules without permeate production (0 L/m2.h) were operated in the same lab-scale MBR. Membrane modules were autopsied after 1, 10, 20 and 30 days of MBR operation, and total extracellular polymeric substances (EPS) accumulated on the membranes were extracted and characterized in detail using several analytical tools, including conventional colorimetric tests (Lowry and Dubois), liquid chromatography with organic carbon detection (LC-OCD), fluorescence excitation - emission matrices (FEEM), fourier transform infrared (FTIR) and confocal laser scanning microscope (CLSM). The transmembrane pressure (TMP) quickly stabilized with higher values for the hydrophobic membranes than hydrophilic ones. The sulfonated polysulfone (SPSU) membrane had the highest negatively charged membrane surface, accumulated the least amount of foulants and displayed the lowest TMP. The same type of organic foulants developed with time on the four membranes and the composition of biopolymers shifted from protein dominance at early stages of filtration (day 1) towards polysaccharides dominance during later stages of MBR filtration. Nonmetric multidimensional scaling of LC-OCD data showed that biofilm samples clustered according to the sampling event (time) regardless of the membrane surface chemistry (hydrophobic or hydrophilic) or operating mode (with or without permeate flux). These results suggest that EPS composition may not be the dominant parameter for evaluating membrane performance and possibly other parameters such as biofilm thickness, porosity, compactness and structure should be considered

  14. Switchable hydrophobic/hydrophilic surface of electrospun poly (L-lactide) membranes obtained by CF4 microwave plasma treatment

    Science.gov (United States)

    Yue, Mengyao; Zhou, Baoming; Jiao, Kunyan; Qian, Xiaoming; Xu, Zhiwei; Teng, Kunyue; Zhao, Lihuan; Wang, Jiajun; Jiao, Yanan

    2015-02-01

    A switchable surface that promotes either hydrophobic or hydrophilic wettability of poly (L-lactide) (PLLA) microfibrous membranes is obtained by CF4 microwave plasma treatment in this paper. The results indicated that both etching and grafting process occurred during the CF4 plasma treatment and these two factors synergistically affected the final surface wettability of PLLA membranes. When plasma treatment was taken under a relatively low power, the surface wettability of PLLA membranes turned from hydrophobic to hydrophilic. Especially when CF4 plasma treatment was taken under 100 W for 10 min and 150 W for 5 min, the water contact angle sharply decreased from 116 ± 3.0° to ∼0°. According to Field-emission scanning electron microscopy (FESEM) results, the PLLA fibers were notably etched by CF4 plasma treatment. Combined with the X-ray photoelectron spectroscopy (XPS) measurements, only a few fluorine-containing groups were grafted onto the surface, so the etching effect directly affected the surface wettability of PLLA membranes in low plasma power condition. However, with the plasma power increasing to 200 W, the PLLA membrane surface turned to hydrophobic again. In contrast, the morphology changes of PLLA fiber surfaces were not obvious while a large number of fluorine-containing groups grafted onto the surface. So the grafting effect gradually became the major factor for the final surface wettability.

  15. Engineering a Highly Hydrophilic PVDF Membrane via Binding TiO₂Nanoparticles and a PVA Layer onto a Membrane Surface.

    Science.gov (United States)

    Qin, Aiwen; Li, Xiang; Zhao, Xinzhen; Liu, Dapeng; He, Chunju

    2015-04-29

    A highly hydrophilic PVDF membrane was fabricated through chemically binding TiO2 nanoparticles and a poly(vinyl alcohol) (PVA) layer onto a membrane surface simultaneously. The chemical composition of the modified membrane surface was determined by X-ray photoelectron spectroscopy, and the binding performance of TiO2 nanoparticles and the PVA layer was investigated by a rinsing test. The results indicated that the TiO2 nanoparticles were uniformly and strongly tailored onto the membrane surface, while the PVA layer was firmly attached onto the surface of TiO2 nanoparticles and the membrane by adsorption-cross-linking. The possible mechanisms during the modification process and filtration performance, i.e., water permeability and bovine serum albumin (BSA) rejection, were investigated as well. Furthermore, antifouling property was discussed through multicycles of BSA solution filtration tests, where the flux recovery ratio was significantly increased from 20.0% for pristine PVDF membrane to 80.5% for PVDF/TiO2/PVA-modified membrane. This remarkable promotion is mainly ascribed to the improvement of surface hydrophilicity, where the water contact angle of the membrane surface was decreased from 84° for pristine membrane to 24° for PVDF/TiO2/PVA membrane. This study presents a novel and varied strategy for immobilization of nanoparticles and PVA layer on substrate surface, which could be easily adapted for a variety of materials for surface modification.

  16. Radius ratio rule for surface hydrophilization of polydimethyl siloxane and silica nanoparticle composite

    Energy Technology Data Exchange (ETDEWEB)

    Toutam, Vijaykumar, E-mail: toutamvk@nplindia.org [Quantum Phenomena and Applications Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012 (India); Jain, Puneet; Sharma, Rina [Quantum Phenomena and Applications Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012 (India); Bathula, Sivaiah; Dhar, Ajay [Material Physics and Engineering Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Marg, New Delhi 110012 (India)

    2015-09-15

    Graphical abstract: - Highlights: • Binary hard sphere silica nanoparticle system based PDMS composite. • Enhanced hydrophilization and retainability of the composite. • Restriction of uncured PDMS from diffusion. • Increased Debye length of electrostatic double layer, measured by F-D Spectroscopy. - Abstract: Polydimethyl siloxane (PDMS) and Silica (SiO{sub 2}) nanoparticle composite blocks of three different batches (CB1–CB3) made by varying the size of SiO{sub 2} nanoparticles (NP), are studied for the degree of hydrophilization and retainability after oxidation by contact angle measurements (CA) and force distance spectroscopy (FDS) using Atomic Force Microscope (AFM). While CA measurements have shown high hydrophilization and retainability for CB3, F-D spectroscopy has reiterated the observation and has shown long range interactive forces and high Debye length of the electrostatic double layer formed. These results are in agreement with the radius ratio rule of binary sphere system for high density packing in the composite and thereby for strong hydrophilization and retainability due to reinforcement and restricted diffusion of uncured polymer.

  17. Mobile and immobile adhesion of staphylococcal strains to hydrophilic and hydrophobic surfaces

    NARCIS (Netherlands)

    Boks, Niels P.; Kaper, Hans J.; Norde, Willem; van der Mei, Henny C.; Busscher, Henk J.

    2009-01-01

    Staphylococcus epidermidis adheres to hydrophilic glass and hydrophobic dimethyldichlorosilane (DDS)-coated glass in similar numbers, but in different modes. Real-time observation of staphylococcal adhesion under a shear rate of 15 s(-1) revealed different adhesion dynamics on both substrata. The nu

  18. Surface modification of imprinted polymer microspheres with ultrathin hydrophilic shells to improve selective recognition of glutathione in aqueous media.

    Science.gov (United States)

    Song, Renyuan; Hu, Xiaoling; Guan, Ping; Li, Ji; Du, Chunbao; Qian, Liwei; Wang, Chaoli

    2016-03-01

    A universal, effective approach addressing the classical limitations of hydrophobic molecularly imprinted polymer (MIP) microspheres was described. Two water-compatible MIP microspheres with ultrathin hydrophilic shells were synthesized by controllable surface-graft polymerization using a charged monomer (methacrylic acid) and uncharged monomer (N-isopropylacrylamide) as the hydrophilic functional monomers for the recognition of glutathione in the aqueous medium. The morphological and chemical characteristics of the as-prepared water-compatible MIP microspheres were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy and contact angle measurements. Their selective recognition properties were investigated by static binding tests and compared with those of the ungrafted MIP microspheres. The results of this study showed that the both as-prepared water-compatible MIP microspheres effectively decreased non-specific binding and enhanced the imprinting factor significantly, and the water-compatible MIP microspheres prepared using N-isopropylacrylamide as monomer exhibited a more remarkable recognition property. In addition, the thickness of surface-grafted hydrophilic layer was well controlled by adjusting the irradiation time to obtain the excellent recognition property. Finally, the applicability of the as-prepared water-compatible MIP microspheres as solid-phase extraction materials was investigated by competitive binding tests using a mixture of glutathione and its analogs.

  19. Six-Year Survival and Early Failure Rate of 2918 Implants with Hydrophobic and Hydrophilic Enossal Surfaces

    Directory of Open Access Journals (Sweden)

    Olivier Le Gac

    2015-02-01

    Full Text Available The aim of this chart review was to obtain an objective, quantitative assessment of the clinical performance of an implant line used in an implantological office setting. Implants with hydrophilic (INICELL and hydrophobic (TST; both: Thommen Medical AG, Grenchen, Switzerland enossal surfaces were compared and the cumulative implant survival rate was calculated. The data of 1063 patients that received 2918 implants (1337 INICELL, 1581 TST was included. The average follow up time was 2.1 (1.1–5.4 years for INICELL and 4.5 (1.3–5.9 years for TST implants (Thommen Medical AG, Switzerland. In the reported period 7 implants with INICELL (0.5% and 23 TST implants (1.5% failed. This difference was statistically significant. The analysis of cases treated and followed up in a single implantological office for 6 years confirmed the very good clinical outcome that was achieved with both used implant lines. Within the limitations of this retrospective analysis, the overall early failure rate of the hydrophilic implants was significantly lower than that of hydrophobic implants. The use of hydrophilic implants allows the clinician to obtain less early failures, hence the interest of an up-to-date surface for the daily work of an implant practice.

  20. Surface modification of imprinted polymer microspheres with ultrathin hydrophilic shells to improve selective recognition of glutathione in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Song, Renyuan, E-mail: songrenyuan0726@163.com; Hu, Xiaoling; Guan, Ping; Li, Ji; Du, Chunbao; Qian, Liwei; Wang, Chaoli

    2016-03-01

    A universal, effective approach addressing the classical limitations of hydrophobic molecularly imprinted polymer (MIP) microspheres was described. Two water-compatible MIP microspheres with ultrathin hydrophilic shells were synthesized by controllable surface-graft polymerization using a charged monomer (methacrylic acid) and uncharged monomer (N-isopropylacrylamide) as the hydrophilic functional monomers for the recognition of glutathione in the aqueous medium. The morphological and chemical characteristics of the as-prepared water-compatible MIP microspheres were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy and contact angle measurements. Their selective recognition properties were investigated by static binding tests and compared with those of the ungrafted MIP microspheres. The results of this study showed that the both as-prepared water-compatible MIP microspheres effectively decreased non-specific binding and enhanced the imprinting factor significantly, and the water-compatible MIP microspheres prepared using N-isopropylacrylamide as monomer exhibited a more remarkable recognition property. In addition, the thickness of surface-grafted hydrophilic layer was well controlled by adjusting the irradiation time to obtain the excellent recognition property. Finally, the applicability of the as-prepared water-compatible MIP microspheres as solid-phase extraction materials was investigated by competitive binding tests using a mixture of glutathione and its analogs. - Highlights: • Ultrathin hydrophilic shell was synthesized by controllable SIP approach. • Low nonspecific binding, high imprinting factor and selectivity were achieved. • Value of imprinting factor was controlled by adjusting irradiation time. • Selective solid-phase extraction of glutathione from a mixed solution of peptides.

  1. Surface Hydrophilicity and Antifungal Properties of TiO2 Films Coated on a Co-Cr Substrate.

    Science.gov (United States)

    Huang, Lijuan; Jing, Shuanglin; Zhuo, Ou; Meng, Xiangfeng; Wang, Xizhang

    2017-01-01

    The purpose of this study was to deposit a thin layer of TiO2 on a Co-Cr substrate, serving as a deactivation film protecting the metallic fitting surface. The crystalline structure and surface morphology of the film were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). A scratch tester was used to examine the adhesion strength between the TiO2 film and the Co-Cr substrate. The water contact angles and antifungal efficacy against C. albicans of the TiO2-deposited Co-Cr samples were investigated and further compared with those of uncoated Co-Cr substrates. The results indicated that a pure anatase microstructure and dense and smooth surface texture as well as strong binding to the underlying metallic surface were obtained. The originally hydrophobic Co-Cr alloy surface turned hydrophilic after TiO2 film coating. Most importantly, the TiO2-coated surface showed a superior antifungal capability under UV-irradiation compared to those without TiO2 coating. This work contains meaningful results for the development of a new metallic framework coating with improved hydrophilicity and antifungal properties.

  2. Surface Hydrophilicity and Antifungal Properties of TiO2 Films Coated on a Co-Cr Substrate

    Directory of Open Access Journals (Sweden)

    Lijuan Huang

    2017-01-01

    Full Text Available The purpose of this study was to deposit a thin layer of TiO2 on a Co-Cr substrate, serving as a deactivation film protecting the metallic fitting surface. The crystalline structure and surface morphology of the film were characterized by X-ray diffraction (XRD and scanning electron microscopy (SEM. A scratch tester was used to examine the adhesion strength between the TiO2 film and the Co-Cr substrate. The water contact angles and antifungal efficacy against C. albicans of the TiO2-deposited Co-Cr samples were investigated and further compared with those of uncoated Co-Cr substrates. The results indicated that a pure anatase microstructure and dense and smooth surface texture as well as strong binding to the underlying metallic surface were obtained. The originally hydrophobic Co-Cr alloy surface turned hydrophilic after TiO2 film coating. Most importantly, the TiO2-coated surface showed a superior antifungal capability under UV-irradiation compared to those without TiO2 coating. This work contains meaningful results for the development of a new metallic framework coating with improved hydrophilicity and antifungal properties.

  3. Speciation of gadolinium in surface water samples and plants by hydrophilic interaction chromatography hyphenated with inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Lindner, Uwe; Lingott, Jana; Richter, Silke; Jakubowski, Norbert; Panne, Ulrich

    2013-02-01

    Hydrophilic interaction chromatography (HILIC) coupled with inductively coupled plasma mass spectrometry (ICP-MS) was optimized for speciation analysis of gadolinium-based contrast agents in environmental samples, in particular surface river waters and plants. Surface water samples from the Teltow channel, near Berlin, were investigated over a distance of 5 km downstream from the influx of a wastewater treatment plant. The total concentration of gadolinium increased significantly from 50 to 990 ng L(-1) due to the influx of the contrast agents. After complete mixing with the river water, the concentration remained constant over a distance of at least 4 km. Two main substances [Dotarem(®) (Gd-DOTA) and Gadovist(®) (Gd-BT-DO3A)] have been identified in the river water using standards. A gadolinium-based contrast agent, possibly Gd-DOTA (Dotarem(®)), was also detected in water plant samples taken from the Teltow channel. Therefore, uptake of contrast agents [Gadovist(®) (Gd-BTDO3A), Magnevist(®) (Gd-DTPA), Omniscan(®) (Gd-DTPA-BMA), Dotarem(®) (Gd-DOTA), and Multihance(®) (Gd-BOPTA)] by plants was investigated in a model experiment using Lepidium sativum (cress plants). HILIC-ICP-MS was used for identification of different contrast agents, and a first approach for quantification using aqueous standard solutions was tested. For speciation analysis, all investigated contrast agents could be extracted from the plant tissues with a recovery of about 54 % for Multihance(®) (Gd-BOPTA) up to 106 % for Gadovist(®) (Gd-BT-DO3A). These experiments demonstrate that all contrast agents investigated are transported from the roots to the leaves where the highest content was measured.

  4. Exploration of surface hydrophilic properties on AISI 304 stainless steel and silicon wafer against aging after atmospheric pressure plasma treatment

    Science.gov (United States)

    Chuang, Shang-I.; Duh, Jenq-Gong

    2014-11-01

    The aim of this work is to seek the enhanced surface hydrophilic properties on AISI 304 stainless steel and silicon wafer after atmospheric pressure plasma treatment using a specifically designed atmospheric pressure plasma jet. The aging tendency of surface hydrophilic property under air is highlighted. It is concluded that both of the silicon wafer and stainless steel treated with plasma generated from supply gas of argon 15 slm mixed with oxygen 40 sccm shows a better tendency on remaining high water contact angle as compared to that with pure argon and nitrogen addition. Additional peaks of O I (777, 844 nm), O II (408 nm) are detected by optical emission spectroscope indicating the presence of the oxygen radicals and ionic species, which interact with surfaces and thus contribute to low water contact angle (WCA) surfaces. Moreover, the result acquired from X-ray photoelectron spectroscopy (XPS) indicates that the increase in the oxygen-related bonding exhibits a better contribution on remaining high surface energy over a period of time.

  5. Osteogenic properties of hydrophilic and hydrophobic titanium surfaces evaluated with osteoblast-like cells (MG63) in coculture with human umbilical vein endothelial cells (HUVEC).

    Science.gov (United States)

    Zhang, Yu; Andrukhov, Oleh; Berner, Simon; Matejka, Michael; Wieland, Marco; Rausch-Fan, Xiaohui; Schedle, Andreas

    2010-11-01

    Osteogenesis on titanium (Ti) surfaces is a complex process involving cell-substrate and cell-cell interaction of osteoblasts and endothelial cells. The aim of this study was to investigate the osteogenic properties of Ti surfaces on osteoblasts in the presence of endothelial cells (ECs). Osteoblast-like cells (MG63 cells) and human umbilical vein endothelial cells (HUVECs) were grown in cocultures on four kinds of Ti surfaces: acid-etched (A), coarse-grit-blasted and acid-etched (SLA), hydrophilic A (modA) and hydrophilic SLA (modSLA) surfaces. MG63 cells in single cultures served as controls. Cell ratios and cell types in cocultures were determined and isolated using flow cytometry. Cell numbers were obtained by direct cell counting. In MG63 cells, alkaline phosphatase (ALP) activity was determined and protein levels of osteocalcin (OC) and osteoprotegerin (OPG) were detected with enzyme-linked immunosorbant assay (ELISA). The mRNA levels of ALP, OC and OPG of sorted MG63 cells were determined with real time polymerase chain reaction (PCR). MG63 cells proliferated in the presence of HUVECs, which showed higher cell numbers on Ti surfaces (A, SLA, modSLA) after 72h, and lower cell numbers on Ti surfaces (modA, SLA, modSLA) after 120h in comparison to single cultures. Protein and mRNA levels of ALP and OPG were higher in cocultures than in single cultures, while OC exhibited a lower expression. These three parameters were higher expressed on modA, SLA and modSLA surfaces compared to A surfaces. Cocultures of osteoblasts and endothelial cells represent the most recently developed research model for investigating osteogenesis and angiogenesis which play both a major role in bone healing. This paper investigates for the first time the osteogenic properties of titanium surfaces used for dental implants with a coculture system with osteoblast-like cells and endothelial cells: (1) In cocultures with ECs (HUVECs) osteoblast-like cells (MG63 cells) show enhanced expression

  6. Structure of DNA-Cationic Surfactant Complexes at Hydrophobically Modified and Hydrophilic Silica Surfaces as Revealed by Neutron Reflectometry

    DEFF Research Database (Denmark)

    Cardenas Gomez, Marite; Wacklin, Hanna; Campbell, Richard A.

    2011-01-01

    In this article, we discuss the structure and composition of mixed DNA-cationic surfactant adsorption layers on both hydrophobic and hydrophilic solid surfaces. We have focused on the effects of the bulk concentrations, the surfactant chain length, and the type solid surface on the interfacial...... layer structure (the location, coverage, and conformation the e DNA and surfactant molecules). Neutron reflectometry is the technique of choice for revealing the surface layer structure by means of selective deuteration. We start by studying the interfacial complexation of DNA...... with dodecyltrimethylammonium bromide (DTAB) and hexadecyltrimethylammonium bromide (CTAB) on hydrophobic surfaces, where we show that DNA molecules are located on top of a self-assembled surfactant monolayer, with the thickness of the DNA layer and the surfactant DNA ratio determined by the surface coverage of the underlying...

  7. Hydrophilicity, photocatalytic activity and stability of tetraethyl orthosilicate modified TiO2 film on glazed ceramic surface

    Science.gov (United States)

    Zhang, Peng; Tian, Jie; Xu, Ruifen; Ma, Guojun

    2013-02-01

    A new, simple, and low-cost method has been developed to enhance the surface properties of TiO2 film. Degussa P25-TiO2 nanoparticles were modified by tetraethyl orthosilicate (TEOS) on glazed ceramic tiles. Effects of tetraethyl orthosilicate modification on microstructure, crystal structure, hydrophilicity, photocatalytic activity and stability of the film were investigated. The obtained results showed that P25-TiO2/TEOS particles exhibited better dispersion, higher surface area, bigger surface roughness and smaller particle size comparing to pure P25-TiO2 particles, which resulted in better hydrophilicity after 10 days in a dark place and higher photocatalytic activity under visible light irradiation. 68% of Rhodamine B was degraded by P25-TiO2/TEOS film in 25 h with the light intensity of 5000 ± 500 lx, and degradation rate reached to 82% with the light intensity of 10,000 ± 1000 lx. Furthermore, two fundamentally different systems, in which the films recycle for repetitive degradation after soaked in dye solution and for discoloration after depositing dye on the surfaces, respectively, were measured to confirm that P25-TiO2/TEOS film showed excellently stable performances. Therefore the P25-TiO2/TEOS film we obtained has good washing resistance and would be a promising candidate for practical applications.

  8. Improvement of Surface Wettability and Hydrophilization of Poly-paraphenylene benzobisoxazole Fiber with Fibrillation Combined Oxygen Plasma Treatment

    Directory of Open Access Journals (Sweden)

    Xiwen Wang

    2012-01-01

    Full Text Available A new surface modification method fibrillation combined with oxygen plasma treatment to improve the wettability and hydrophily of PBO fiber was studied in this paper. The surface chemical structure and morphology of PBO fiber were characterized by the methods of FTIR, XPS and SEM. The wettability and hydrophlic characters changes on the surface were evaluated by the dynamic contact angle system and image analysis. The results show that the increase surface roughness by fibrillation could improve the wettability. Fibrillation combined oxygen plasma treatment has a better effect than oxygen plasma treatment to improve the wettability and hdyrophlization of PBO fiber. The specific area of PBO fiber increased to 10.7 m2/g from 0.7 m2/g, contact angle decreased to 43.2° from 84.4° and WRV increased to 208.4% from 13.7%. The modified fibers have a good dispersion in water for hydrophilization improvement.

  9. Glycidol-modified gels for molecular-sieve chromatography. Surface hydrophilization and pore size reduction.

    Science.gov (United States)

    Eriksson, K O

    1987-11-01

    Divinyl sulfone-crosslinked agarose gels were made hydrophilic by coupling glycidol to the agarose chains. The concentration of glycidol in the reaction mixture determines the pore size of the gels (the glycidol molecules probably form polymers, the degree of polymerization increasing with the glycidol concentration). Gels prepared with moderate glycidol concentrations are still porous enough to be used for separation of proteins and peptides. Gels with a high degree of glycidol polymerization are suited for desalting of low-molecular-weight compounds, for instance peptides.

  10. Hydrophilic Modification of Microporous Polysulfone Membrane via Surface-Initiated Atom Transfer Radical Polymerization and Hydrolysis of Poly(glycidylmethacrylate)%Hydrophilic Modification of Microporous Polysulfone Membrane via Surface-Initiated Atom Transfer Radical Polymerization and Hydrolysis of Poly(glycidylmethacrylate)

    Institute of Scientific and Technical Information of China (English)

    王超展; 赵飒; 卫引茂

    2012-01-01

    Poly(glycidylmethacrylate) (PGMA) brushes were grafted from chloromethylated polysulfone (CMPSF) mem- brane surface by surface-initiated atom transfer radical polymerization (S1-ATRP), and the grafting was followed by hydrolysis of epoxy groups in the grafting chains to improve the membrane's hydrophilie property. Fourier trans- form infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) measurements confirmed the suc- cessful grafting and hydrolysis of PGMA. The grafting degree of the monomer, measured by periodic acid titration and gravimetric analysis, increased linearly with the polymerization time, while the static water contact angle of the membrane grafted with PGMA or hydrolyzed PGMA linearly decreased. In comparison with the PGMA-grafted membranes, the hydrolyzed PGMA-grafted membranes possess stronger hydrophilicity as indicated by their contact angle and hydration capacity, and as a result they have an improved antifouling property. Therefore, the control of the hydrophilicity of PSF membrane could be realized through adjusting the polymerization time and transforming the functional groups in the grafting chain.

  11. Nonlinear Porous Diffusion Modeling of Hydrophilic Ionic Agrochemicals in Astomatous Plant Cuticle Aqueous Pores: A Mechanistic Approach

    Directory of Open Access Journals (Sweden)

    Eloise C. Tredenick

    2017-05-01

    Full Text Available The agricultural industry requires improved efficacy of sprays being applied to crops and weeds in order to reduce their environmental impact and deliver improved financial returns. Enhanced foliar uptake is one means of improving efficacy. The plant leaf cuticle is known to be the main barrier to diffusion of agrochemicals within the leaf. The usefulness of a mathematical model to simulate uptake of agrochemicals in plant cuticles has been noted previously in the literature, as the results of each uptake experiment are specific to each formulation of active ingredient, plant species and environmental conditions. In this work we develop a mathematical model and numerical simulation for the uptake of hydrophilic ionic agrochemicals through aqueous pores in plant cuticles. We propose a novel, nonlinear, porous diffusion model for ionic agrochemicals in isolated cuticles, which extends simple diffusion through the incorporation of parameters capable of simulating: plant species variations, evaporation of surface droplet solutions, ion binding effects on the cuticle surface and swelling of the aqueous pores with water. We validate our theoretical results against appropriate experimental data, discuss the key sensitivities in the model and relate theoretical predictions to appropriate physical mechanisms. Major influencing factors have been found to be cuticle structure, including tortuosity and density of the aqueous pores, and to a lesser extent humidity and cuticle surface ion binding effects.

  12. Evolution and accumulation of organic foulants on hydrophobic and hydrophilic membrane surfaces in a submerged membrane bioreactor

    KAUST Repository

    Matar, Gerald

    2015-09-07

    Membrane surface modification is attracting more attention to mitigate biofouling in membrane bioreactors (MBRs). Five membranes differing in chemistry and hydrophobic/hydrophilic potential were run in parallel in a lab-scale MBR under the same conditions. Membranes were sampled after 1, 10, 20 and 30 days of MBR operation with synthetic wastewater. Subsequently, accumulated organic foulants were characterised using several chemical analytical tools. Results showed similar development of organic foulants with time, illustrating that membrane surface chemistry did not affect the selection of specific organic foulants. Multivariate analysis showed that biofilm samples clustered according to the day of sampling. The composition of organic foulants shifted from protein-like substances towards humics and polysaccharides-like substances. We propose that to control biofouling in MBRs, one should focus less on the membrane surface chemistry.

  13. The surface reactivity of chalk (biogenic calcite) with hydrophilic and hydrophobic functional groups

    Science.gov (United States)

    Okhrimenko, D. V.; Dalby, K. N.; Skovbjerg, L. L.; Bovet, N.; Christensen, J. H.; Stipp, S. L. S.

    2014-03-01

    The surface properties of calcium carbonate minerals play an important role in a number of industrial and biological processes. Properties such as wettability and adsorption control liquid-solid interface behaviour and thus have a strong influence on processes such as biomineralisation, remediation of aquifers and oil recovery. We investigated how two model molecules of different polarity, namely water and ethanol, interact with reservoir and outcrop chalk samples and we compared their behaviour with that of pure, inorganically precipitated calcite. Thermodynamic quantities, such as the work of wetting, surface energy and isosteric adsorption enthalpy, were determined from vapour adsorption isotherms. The chalks were studied fresh and after extraction of organic residues that were originally present in these samples. The work of wetting correlates with the amount of organic matter present in the chalk samples but we observed a fundamental difference between the adsorption properties of chalk and pure, inorganically precipitated calcite toward the less polar, ethanol molecule. Further analysis of the chemical composition of the organic matter extracted from the chalk samples was made by gas chromatography (GC-MS). Monitoring surface composition by X-ray photoelectron spectroscopy (XPS) before and after extraction of the organic material, and with atomic force microscopy (AFM), showed that nanometer sized clay crystals observed on the chalk particle surfaces could be an important part of the reason for the differences. Removal of the extractable portion of the hydrocarbons liberates adsorption sites that have different wetting properties than the rest of the chalk and these have an energy distribution that is similar to clays. Thus, the results exemplify the complexity of biogenic calcite adsorption behaviour and demonstrate that chalk wetting in drinking water aquifers as well as oil reservoirs is controlled partly by the nanoparticles of clay that have grown on the

  14. Controlled surface morphology and hydrophilicity of polycaprolactone toward selective differentiation of mesenchymal stem cells to neural like cells.

    Science.gov (United States)

    Jahani, Hoda; Jalilian, Farid Azizi; Wu, Chia-Yu; Kaviani, Saeid; Soleimani, Masoud; Abassi, Naghmeh; Ou, Keng-Liang; Hosseinkhani, Hossein

    2015-05-01

    Differentiation of mesenchymal stem cells (MSCs) into neuron cells has great potential in therapy of damaged nerve tissue. It has been shown that three-dimensional biomaterials have great ability to up regulate the expression of neuronal proteins. In this study, O2 plasma technology was used to enhance hydrophilicity of poly (ε-caprolactone) (PCL) toward selective differentiation of MSCs into neural cells. Random and aligned PCL nanofibers scaffolds were fabricated by electrospinning method and their physicochemical and mechanical properties were carried out by scanning electron microscope (SEM), contact angle, and tensile measurements. Contact angle studies of PCL and plasma treated PCL (p-PCL) nanofibers revealed significant change on the surface properties PCL nanofibers from the view point of hydrophilicity. Physiochemical studies revealed that p-PCL nanofibers were extremely hydrophilic compared with untreated PCL nanofibers which were highly hydrophobic and nonabsorbent to water. Differentiation of MSCs were carried out by inducing growth factors including basic fibroblast growth factor, nerve growth factor, and brain derived growth factor, NT3, 3-isobutyl-1-methylxanthine (IBMX) in Dulbecco's modified Eagle's medium/F12 media. Differentiated MSCs on nanofibrous scaffold were examined by immunofluorescence assay and was found to express the neuronal proteins; β-tubulin III and Map2, on day 15 after cell culture. The real-time polymerase chain reaction (RT-PCR) analysis showed that p-PCL nanofibrous scaffold could upregulate expression of Map-2 and downregulate expression of Nestin genes in nerve cells differentiated from MSCs. This study indicates that mesenchymal stem cell cultured on nanofibrous scaffold have potential differentiation to neuronal cells on and could apply in nerve tissue repair.

  15. Hydrophilic modification of poly(ether sulfone) ultrafiltration membrane surface by self-assembly of TiO 2 nanoparticles

    Science.gov (United States)

    Luo, Ming-Liang; Zhao, Jian-Qing; Tang, Wu; Pu, Chun-Sheng

    2005-08-01

    Membrane fouling is one of the major obstacles for reaching the ultimate goal, which realizes high flux over a prolonged period of ultrafiltration (UF) operation. In this paper, TiO 2 nanoparticles of a quantum size (40 nm or less) in anatase crystal structure were prepared from the controlled hydrolysis of titanium tetraisopropoxide and characterized by X-ray diffraction (XRD) analysis and transmission electron microscopy (TEM). The hydrophilic modification of poly(ether sulfone) UF membrane was performed by self-assembly of the hydroxyl group of TiO 2 nanoparticle surface and the sulfone group and ether bond in poly(ether sulfone) structure through coordination and hydrogen bond interaction, which was ascertained by X-ray photoelectron spectroscopy (XPS). The morphology and hydrophilicity were characterized by scanning electron microscopy (SEM) and contact angle test, respectively. The composite UF membrane was also characterized in terms of separation behavior for polyethylene glycol-5000 solute. The experimental results show that the composite UF membrane has good separation performance and offers a strong potential for possible use as a new type of anti-fouling UF membrane.

  16. Effects of hydrophilicity and microtopography of titanium implant surfaces on initial supragingival plaque biofilm formation. A pilot study.

    Science.gov (United States)

    Schwarz, F; Sculean, A; Wieland, M; Horn, N; Nuesry, E; Bube, C; Becker, J

    2007-12-01

    The aim of the present pilot study is to investigate the effects of hydrophilicity and microtopography of titanium implant surfaces on initial supragingival plaque biofilm formation. Test specimens were manufactured from commercially pure grade 2 titanium according to one of the following procedures: polished (P), acid-etched (A), chemically modified (mod) A (modA), sand-blasted large grit and A (SLA), and modSLA. Intraoral splints were used to collect an in vivo supragingival plaque biofilm in each group at 12, 24, and 48 h. Stained plaque biofilm (PB) areas (%) were morphometrically assessed. All groups exhibited significant increases of mean PB areas over time (p P > A =modA (p modSLA = P > A = modA (p A = modA (p < 0.001; respectively). Within the limits of a pilot study, it could be concluded that hydrophilicity had no apparent effect, while microtopography had a highly uneven and unpredictable influence on supragingival plaque biofilm formation.

  17. Effect of low-concentration rhamnolipid on transport of Pseudomonas aeruginosa ATCC 9027 in an ideal porous medium with hydrophilic or hydrophobic surfaces.

    Science.gov (United States)

    Zhong, Hua; Liu, Guansheng; Jiang, Yongbing; Brusseau, Mark L; Liu, Zhifeng; Liu, Yang; Zeng, Guangming

    2016-03-01

    The success of effective bioaugmentation processes for remediation of soil and groundwater contamination requires effective transport of the injected microorganisms in the subsurface environment. In this study, the effect of low concentrations of monorhamnolipid biosurfactant solutions on transport of Pseudomonas aeruginosa in an ideal porous medium (glass beads) with hydrophilic or hydrophobic surfaces was investigated by conducting miscible-displacement experiments. Transport behavior was examined for both glucose-grown and hexadecane-grown cells, with low and high surface hydrophobicity, respectively. A clean-bed colloid deposition model was used for determination of deposition rate coefficients. Results show that cells with high surface hydrophobicity exhibit greater retention than cells with low surface hydrophobicity. Rhamnolipid affects cell transport primarily by changing cell surface hydrophobicity, with an additional minor effect by increasing solution ionic strength. There is a good linear relation between k and rhamnolipid-regulated cell surface hydrophobicity presented as bacterial-adhesion-to-hydrocarbon (BATH) rate of cells (R(2)=0.71). The results of this study show the importance of hydrophobic interaction for transport of bacterial cells in silica-based porous media, and the potential of using low-concentration rhamnolipid solutions for facilitating bacterial transport in bioaugmentation efforts.

  18. Possible time-dependent effect of ions and hydrophilic surfaces on the electrical conductivity of aqueous solutions.

    Science.gov (United States)

    Verdel, Nada; Jerman, Igor; Krasovec, Rok; Bukovec, Peter; Zupancic, Marija

    2012-01-01

    The purpose of this work was to determine the influence of mechanical and electrical treatment on the electrical conductivity of aqueous solutions. Solutions were treated mechanically by iteration of two steps: 1:100 dilution and vigorous shaking. These two processes were repeated until extremely dilute solutions were obtained. For electrical treatment the solutions were exposed to strong electrical impulses. Effects of mechanical (as well as electrical) treatment could not be demonstrated using electrical conductivity measurements. However, significantly higher conductivity than those of the freshly prepared chemically analogous solutions was found in all aged solutions except for those samples stored frozen. The results surprisingly resemble a previously observed weak gel-like behavior in water stored in closed flasks. We suggest that ions and contact with hydrophilic glass surfaces could be the determinative conditions for the occurrence of this phenomenon.

  19. Possible Time-Dependent Effect of Ions and Hydrophilic Surfaces on the Electrical Conductivity of Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Marija Zupancic

    2012-03-01

    Full Text Available The purpose of this work was to determine the influence of mechanical and electrical treatment on the electrical conductivity of aqueous solutions. Solutions were treated mechanically by iteration of two steps: 1:100 dilution and vigorous shaking. These two processes were repeated until extremely dilute solutions were obtained. For electrical treatment the solutions were exposed to strong electrical impulses. Effects of mechanical (as well as electrical treatment could not be demonstrated using electrical conductivity measurements. However, significantly higher conductivity than those of the freshly prepared chemically analogous solutions was found in all aged solutions except for those samples stored frozen. The results surprisingly resemble a previously observed weak gel-like behavior in water stored in closed flasks. We suggest that ions and contact with hydrophilic glass surfaces could be the determinative conditions for the occurrence of this phenomenon.

  20. From hydration repulsion to dry adhesion between asymmetric hydrophilic and hydrophobic surfaces

    OpenAIRE

    Kanduč, Matej; Netz, Roland R.

    2015-01-01

    Besides van der Waals and electrostatic interactions, surfaces in water experience solvation forces arising from the interfacial water structure that become dominant at small surface separations. Using a combination of atomistic simulations and theoretical arguments, we construct a universal adhesion state diagram for two neutral surfaces with different water affinities. We find an intermediate regime of affinity combinations where the surfaces adhere to each other without an intervening wate...

  1. Surface hydrophilic modification with a sugar moiety for a uniform-sized polymer molecularly imprinted for phenobarbital in serum.

    Science.gov (United States)

    Hua, Kuichang; Zhang, Lei; Zhang, Zhenhui; Guo, Yong; Guo, Tianying

    2011-08-01

    A uniform-sized polymer molecularly imprinted for phenobarbital, which is surface modified by a sugar moiety, has been prepared through a two-step swelling polymerization method using polystyrene beads as seeds, phenobarbital as the template, 4-vinylpyridine as a functional monomer, ethylene glycol dimethacrylate as a cross-linker and 2-O-meth-acryloyloxyethoxyl-(2,3,4,6- tetra-O-acetyl-β-d-galactopyranosyl)-(1-4)-2,3,6-tri-O-acetyl-β-d-glucopyranoside as a surface-modifying glycomonomer, respectively. After deprotecting the glycopolymer, a surface sugar moiety-modified, hydrophilic, molecularly imprinted polymer for phenobarbital (glyco-MIP) was obtained. The resulting polymer beads were packed into a stainless steel column to evaluate their chromatographic characteristics by high-performance liquid chromatography (HPLC). Good selectivity for phenobarbital was obtained with the glyco-MIP compared to the unmodified molecularly imprinted polymer, which revealed that the recognition sites of phenobarbital were unchanged with sugar moiety surface modification. Furthermore, bovine serum albumin was almost completely recovered from the glyco-MIP column, which indicates that the glyco-MIP materials can be used to separate and analyze drugs in complex samples, such as biological samples. The results of pretreatment with and analysis of phenobarbital in serum suggest that this material can be used to analyze phenobarbital in serum through a pretreatment and reverse-phase HPLC analysis process. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  2. Preparation of hydrophilic poly(lactic acid) tissue engineering scaffold via (PLA)-(PLA-b-PEG)-(PEG) solution casting and thermal-induced surface structural transformation.

    Science.gov (United States)

    Zhu, Xiaomin; Zhong, Tian; Huang, Ran; Wan, Ajun

    2015-01-01

    Porous poly(lactic acid) (PLA) tissue engineering scaffolds with a hydrophilic surface assembled by polyethylene glycol aggregations were prepared by the solvent casting/particulate leaching method from (PLA)-(PLA-b-PEG)-(PEG) blend solution, where the PLA-b-PEG block polymer serves as an amphiphilic glue between two phases. A thermal recrystallization process was inserted before leaching to induce a phase separation, which subsequently squeezes out PEG to form a hydrophilic shell. Characterizations of XRD and DSC indicated the composition and mixing states of materials. The water contact angle test qualitatively presented the excellent hydrophilicity compared to the pure PLA or PLA-PEG simple blend scaffold. The scanning electron microscope results confirmed the formation of porous structure of [Formula: see text] pore size, with an observable phase separation on the surface. The scaffold was degraded in PBS at [Formula: see text], and the degradation exhibits a three-stage behavior, which evidenced the amphiphilically glued phase separations.

  3. Dynamic Mathematical Modelling of the Removal of Hydrophilic VOCs by Biotrickling Filters

    Directory of Open Access Journals (Sweden)

    Pau San-Valero

    2015-01-01

    Full Text Available A mathematical model for the simulation of the removal of hydrophilic compounds using biotrickling filtration was developed. The model takes into account that biotrickling filters operate by using an intermittent spraying pattern. During spraying periods, a mobile liquid phase was considered, while during non-spraying periods, a stagnant liquid phase was considered. The model was calibrated and validated with data from laboratory- and industrial-scale biotrickling filters. The laboratory experiments exhibited peaks of pollutants in the outlet of the biotrickling filter during spraying periods, while during non-spraying periods, near complete removal of the pollutant was achieved. The gaseous outlet emissions in the industrial biotrickling filter showed a buffered pattern; no peaks associated with spraying or with instantaneous variations of the flow rate or inlet emissions were observed. The model, which includes the prediction of the dissolved carbon in the water tank, has been proven as a very useful tool in identifying the governing processes of biotrickling filtration.

  4. Kinetic Modelling of Drug Release from Pentoxifylline Matrix Tablets based on Hydrophilic, Lipophilic and Inert Polymers

    Directory of Open Access Journals (Sweden)

    Mircia Eleonora

    2015-12-01

    Full Text Available Pentoxifylline is a xanthine derivative used in the treatment of peripheral vascular disease, which because of its pharmacokinetic and pharmacologic profile is an ideal candidate for the development of extended release formulations. The aim of this study is to present a kinetic analysis of the pentoxifylline release from different extended release tablets formulations, using mechanistic and empirical kinetic models. A number of 28 formulations were prepared and analysed; the analysed formulations differed in the nature of the matrix forming polymers (hydrophilic, lipophilic, inert and in their concentrations. Measurements were conducted in comparison with the reference product Trental 400 mg (Aventis Pharma. The conditions for the dissolution study were according to official regulations of USP 36: apparatus no. 2, dissolution medium water, volume of dissolution medium is 1,000 mL, rotation speed is 50 rpm, spectrophotometric assay at 274 nm. Six mathematical models, five mechanistic (0 orders, 1st-order release, Higuchi, Hopfenberg, Hixson-Crowell and one empirical (Peppas, were fitted to pentoxifylline dissolution profile from each pharmaceutical formulation. The representative model describing the kinetics of pentoxifylline release was the 1st-order release, and its characteristic parameters were calculated and analysed.

  5. Increase in the water contact angle of composite film surfaces caused by the assembly of hydrophilic nanocellulose fibrils and nanoclay platelets.

    Science.gov (United States)

    Wu, Chun-Nan; Saito, Tsuguyuki; Yang, Quanling; Fukuzumi, Hayaka; Isogai, Akira

    2014-08-13

    Controlling the assembly modes of different crystalline nanoparticles in composites is important for the expression of specific characteristics of the assembled structures. We report a unique procedure for increasing water contact angles (CAs) of composite film surfaces via the assembly of two different hydrophilic components, nanocellulose fibrils and nanoclay platelets. The nanocellulose fibrils and nanoclay platelets used have ionic groups on their surfaces in high densities (∼1 mmol g(-1)) and have no hydrophobic surface. The increase in the CA of the nanocellulose/nanoclay composite films was thus analyzed on the basis of the air area fractions of their nanostructured surfaces following Cassie's law. The air area fractions were geographically estimated from the atomic force microscopy height profiles of the composite film surfaces. The CAs of the composite film surfaces were found to be well described by Cassie's law. Interestingly, the composite films consisting of two hydrophilic nanoelements with different shapes exhibited CAs larger than those of the individual neat films.

  6. Hydrophilization of Poly(ether ether ketone) Films by Surface-initiated Atom Transfer Radical Polymerization

    DEFF Research Database (Denmark)

    Fristrup, Charlotte Juel; Eskimergen, Rüya; Burkrinsky, J.T.

    2008-01-01

    -modified PEEK using Surface-Initiated Atom Transfer Radical Polymerization (SI ATRP). Surface reduction of PEEK to form hydroxyl groups [1, 2, 3] was .performed prior to the attachment of 2-bromoisobutyrate initiating groups. Each modification step of PEEK as well as the polymer grafting was followed...... and confirmed by ATR FTIR, water contact ang;le, and Thermal Gravimetric Analysis (TGA). The surface topography was evaluated by "Atomic Force Microscopy (AFM). X-ray Photoelectron Spectroscopy (XPS) has been used to investigate the degree of functionalization. The performed modification allowed for successful...

  7. Hydrophilization of Poly(ether ether ketone) Films by Surface-initiated Atom Transfer Radical Polymerization

    DEFF Research Database (Denmark)

    Fristrup, Charlotte Juel; Eskimergen, Rüya; Burkrinsky, J.T.

    2008-01-01

    -modified PEEK using Surface-Initiated Atom Transfer Radical Polymerization (SI ATRP). Surface reduction of PEEK to form hydroxyl groups [1, 2, 3] was .performed prior to the attachment of 2-bromoisobutyrate initiating groups. Each modification step of PEEK as well as the polymer grafting was followed...... and confirmed by ATR FTIR, water contact ang;le, and Thermal Gravimetric Analysis (TGA). The surface topography was evaluated by "Atomic Force Microscopy (AFM). X-ray Photoelectron Spectroscopy (XPS) has been used to investigate the degree of functionalization. The performed modification allowed for successful...

  8. Selective three-dimensional hydrophilization of microstructured polymer surfaces through confined photocatalytic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Ammosova, Lena; Jiang, Yu; Suvanto, Mika; Pakkanen, Tapani A., E-mail: tapani.pakkanen@uef.fi

    2015-02-28

    Graphical abstract: - Highlights: • Microstructured polymer surfaces with selective 3-D anisotropy were created. • Selective UV treatment was performed to alter surface wettability. • Removable meshes resembling a photomask were applied during UV treatment. • Micropatterning by viscous polymer on solid surface was performed. - Abstract: While the conventional photomask technique gives only two-dimensional anisotropies, in this study we fabricated microstructured polymer surfaces with a selective three-dimensional anisotropy. With the applied removable mesh, we were able to confine the contacting area between the surface and photoinitiator and provide three-dimensional wettability anisotropies. Different types of meshes were used depending on the desired micropatterns shape, size and substrate material. The results revealed the three-dimensional anisotropic micropits pattern with depth profiles, which would be applicable for the confinement and patterning of cells and biomolecules. In addition, the proposed method is applicable for creating selectively activated polymer surface as a substrate for further atomic layer deposition. Moreover, we demonstrate a low cost and fast mass productive method for patterning a viscous polymer liquid in a micro-sized scale.

  9. Hydrophobic and hydrophilic interactions in aqueous mixtures of alcohols at a hydrophobic surface.

    Science.gov (United States)

    Ballal, Deepti; Chapman, Walter G

    2013-09-21

    Aqueous solutions of alcohols are interesting because of their anomalous behavior that is believed to be due to the molecular structuring of water and alcohol around each other in solution. The interfacial structuring and properties are significant for application in alcohol purification processes and biomolecular structure. Here we study aqueous mixtures of short alcohols (methanol, ethanol, 1-propanol, and 2-propanol) at a hydrophobic surface using interfacial statistical associating fluid theory which is a perturbation density functional theory. The addition of a small amount of alcohol decreases the interfacial tension of water drastically. This trend in interfacial tension can be explained by the structure of water and alcohol next to the surface. The hydrophobic group of an added alcohol preferentially goes to the surface preserving the structure of water in the bulk. For a given bulk alcohol concentration, water mixed with the different alcohols has different interfacial tensions with propanol having a lower interfacial tension than methanol and ethanol. 2-propanol is not as effective in decreasing the interfacial tension as 1-propanol because it partitions poorly to the surface due to its larger excluded volume. But for a given surface alcohol mole fraction, all the alcohol mixtures give similar values for interfacial tension. For separation of alcohol from water, methods that take advantage of the high surface mole fraction of alcohol have advantages compared to separation using the vapor in equilibrium with a water-alcohol liquid.

  10. Investigating Hydrophilic Pores in Model Lipid Bilayers Using Molecular Simulations: Correlating Bilayer Properties with Pore-Formation Thermodynamics.

    Science.gov (United States)

    Hu, Yuan; Sinha, Sudipta Kumar; Patel, Sandeep

    2015-06-23

    Cell-penetrating and antimicrobial peptides show a remarkable ability to translocate across physiological membranes. Along with factors such as electric-potential-induced perturbations of membrane structure and surface tension effects, experiments invoke porelike membrane configurations during the solute transfer process into vesicles and cells. The initiation and formation of pores are associated with a nontrivial free-energy cost, thus necessitating a consideration of the factors associated with pore formation and the attendant free energies. Because of experimental and modeling challenges related to the long time scales of the translocation process, we use umbrella sampling molecular dynamics simulations with a lipid-density-based order parameter to investigate membrane-pore-formation free energy employing Martini coarse-grained models. We investigate structure and thermodynamic features of the pore in 18 lipids spanning a range of headgroups, charge states, acyl chain lengths, and saturation. We probe the dependence of pore-formation barriers on the area per lipid, lipid bilayer thickness, and membrane bending rigidities in three different lipid classes. The pore-formation free energy in pure bilayers and peptide translocating scenarios are significantly coupled with bilayer thickness. Thicker bilayers require more reversible work to create pores. The pore-formation free energy is higher in peptide-lipid systems than in peptide-free lipid systems due to penalties to maintain the solvation of charged hydrophilic solutes within the membrane environment.

  11. The effect of urea and taurine as hydrophilic penetration enhancers on stratum corneum lipid models.

    Science.gov (United States)

    Mueller, J; Oliveira, J S L; Barker, R; Trapp, M; Schroeter, A; Brezesinski, G; Neubert, R H H

    2016-09-01

    To optimize transdermal application of drugs, the barrier function of the skin, especially the stratum corneum (SC), needs to be reduced reversibly. For this purpose, penetration enhancers like urea or taurine are applied. Until now, it is unclear if this penetration enhancement is caused by an interaction with the SC lipid matrix or related to effects within the corneocytes. Therefore, the effects of both hydrophilic enhancers on SC models with different dimensionality, ranging from monolayers to multilayers, have been investigated in this study. Many sophisticated methods were applied to ascertain the mode of action of both substances on a molecular scale. The experiments reveal that there is no specific interaction when 10% urea or 5% taurine solutions are added to the SC model systems. No additional water uptake in the head group region and no decrease of the lipid chain packing density have been observed. Consequently, we suppose that the penetration enhancing effect of both substances might be based on the introduction of large amounts of water into the corneocytes, caused by the enormous water binding capacity of urea and a resulting osmotic pressure in case of taurine.

  12. Mechanism of formation of humus coatings on mineral surfaces 2. Attenuated total reflectance spectra of hydrophobic and hydrophilic fractions of organic acids from compost leachate on alumina

    Science.gov (United States)

    Wershaw, R. L.; Llaguno, E.C.; Leenheer, J.A.; Sperline, R.P.; Song, Y.

    1996-01-01

    Hydrophobic and hydrophilic fractions were isolated from a compost leachate. The adsorption isotherms of both fractions on alumina were measured by attenuated total reflectance infrared spectroscopy. The shapes of the adsorption isotherms of the two fractions were different. The isotherms for the hydrophilic fraction showed little change in surface excess with increasing solution concentration above 4 mg L-1. The isotherms for the hydrophobic fraction, on the other hand, displayed a marked increase in surface excess with increasing solution concentration. This increase is evidence for the formation of aggregates (admicelles or hemimicelles) on the alumina surface. Linear dichroism calculations indicated that more of the carboxylate groups in the adsorbed hydrophobic molecules than in the absorbed hydrophilic fraction were free to rotate. The hindered rotation of the carboxylate groups in the adsorbed hydrophilic-fraction molecules probably indicates that these groups are bound to surface aluminum ions by a bidentate mechanism in which the two oxygen atoms of a single carboxylate group bind to separate aluminum ions.

  13. Wang-Landau sampling in face-centered-cubic hydrophobic-hydrophilic lattice model proteins.

    Science.gov (United States)

    Liu, Jingfa; Song, Beibei; Yao, Yonglei; Xue, Yu; Liu, Wenjie; Liu, Zhaoxia

    2014-10-01

    Finding the global minimum-energy structure is one of the main problems of protein structure prediction. The face-centered-cubic (fcc) hydrophobic-hydrophilic (HP) lattice model can reach high approximation ratios of real protein structures, so the fcc lattice model is a good choice to predict the protein structures. The lacking of an effective global optimization method is the key obstacle in solving this problem. The Wang-Landau sampling method is especially useful for complex systems with a rough energy landscape and has been successfully applied to solving many optimization problems. We apply the improved Wang-Landau (IWL) sampling method, which incorporates the generation of an initial conformation based on the greedy strategy and the neighborhood strategy based on pull moves into the Wang-Landau sampling method to predict the protein structures on the fcc HP lattice model. Unlike conventional Monte Carlo simulations that generate a probability distribution at a given temperature, the Wang-Landau sampling method can estimate the density of states accurately via a random walk, which produces a flat histogram in energy space. We test 12 general benchmark instances on both two-dimensional and three-dimensional (3D) fcc HP lattice models. The lowest energies by the IWL sampling method are as good as or better than those of other methods in the literature for all instances. We then test five sets of larger-scale instances, denoted by the S, R, F90, F180, and CASP target instances on the 3D fcc HP lattice model. The numerical results show that our algorithm performs better than the other five methods in the literature on both the lowest energies and the average lowest energies in all runs. The IWL sampling method turns out to be a powerful tool to study the structure prediction of the fcc HP lattice model proteins.

  14. Amphiphilic surface active triblock copolymers with mixed hydrophobic and hydrophilic side chains for tuned marine fouling-release properties.

    Science.gov (United States)

    Park, Daewon; Weinman, Craig J; Finlay, John A; Fletcher, Benjamin R; Paik, Marvin Y; Sundaram, Harihara S; Dimitriou, Michael D; Sohn, Karen E; Callow, Maureen E; Callow, James A; Handlin, Dale L; Willis, Carl L; Fischer, Daniel A; Kramer, Edward J; Ober, Christopher K

    2010-06-15

    Two series of amphiphilic triblock surface active block copolymers (SABCs) were prepared through chemical modification of two polystyrene-block-poly(ethylene-ran-butylene)-block-polyisoprene ABC triblock copolymer precursors. The methyl ether of poly(ethylene glycol) [M(n) approximately 550 g/mol (PEG550)] and a semifluorinated alcohol (CF(3)(CF(2))(9)(CH(2))(10)OH) [F10H10] were attached at different molar ratios to impart both hydrophobic and hydrophilic groups to the isoprene segment. Coatings on glass slides consisting of a thin layer of the amphiphilic SABC deposited on a thicker layer of an ABA polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene thermoplastic elastomer were prepared for biofouling assays with algae. Dynamic water contact angle analysis, X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) measurements were utilized to characterize the surfaces. Clear differences in surface structure were realized as the composition of attached side chains was varied. In biofouling assays, the settlement (attachment) of zoospores of the green alga Ulva was higher for surfaces incorporating a large proportion of the hydrophobic F10H10 side chains, while surfaces with a large proportion of the PEG550 side chains inhibited settlement. The trend in attachment strength of sporelings (young plants) of Ulva did not show such an obvious pattern. However, amphiphilic SABCs incorporating a mixture of PEG550 and F10H10 side chains performed the best. The number of cells of the diatom Navicula attached after exposure to flow decreased as the content of PEG550 to F10H10 side chains increased.

  15. Method development and validation for optimised separation of salicylic, acetyl salicylic and ascorbic acid in pharmaceutical formulations by hydrophilic interaction chromatography and response surface methodology.

    Science.gov (United States)

    Hatambeygi, Nader; Abedi, Ghazaleh; Talebi, Mohammad

    2011-09-02

    This paper introduces a design of experiments (DOE) approach for method optimisation in hydrophilic interaction chromatography (HILIC). An optimisation strategy for the separation of acetylsalicylic acid, its major impurity salicylic acid and ascorbic acid in pharmaceutical formulations by HILIC is presented, with the aid of response surface methodology (RSM) and Derringer's desirability function. A Box-Behnken experimental design was used to build the mathematical models and then to choose the significant parameters for the optimisation by simultaneously taking both resolution and retention time as the responses. The refined model had a satisfactory coefficient (R²>0.92, n=27). The four independent variables studied simultaneously were: acetonitrile content of the mobile phase, pH and concentration of buffer and column temperature each at three levels. Of these, the concentration of buffer and its cross-product with pH had a significant, positive influence on all studied responses. For the test compounds, the best separation conditions were: acetonitrile/22 mM ammonium acetate, pH 4.4 (82:18, v/v) as the mobile phase and column temperature of 28°C. The methodology also captured the interaction between variables which enabled exploration of the retention mechanism involved. It would be inferred that the retention is governed by a compromise between hydrophilic partitioning and ionic interaction. The optimised method was further validated according to the ICH guidelines with respect to linearity and range, precision, accuracy, specificity and sensitivity. The robustness of the method was also determined and confirmed by overlying counter plots of responses which were derived from the experimental design utilised for method optimisation.

  16. Improved blood compatibility of polyethersulfone membrane with a hydrophilic and anionic surface.

    Science.gov (United States)

    Nie, Shengqiang; Xue, Jimin; Lu, Yi; Liu, Yeqiu; Wang, Dongsheng; Sun, Shudong; Ran, Fen; Zhao, Changsheng

    2012-12-01

    In this study, a novel triblock copolymer of poly (styrene-co-acrylic acid)-b-poly (vinyl pyrrolidone)-b-poly(styrene-co-acrylic acid) (P(St-co-AA)-b-PVP-b-P(St-co-AA)) is synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization, and used for the modification of blood contacting surface of polyethersulfone (PES) membrane to improve blood compatibility. The synthesized block copolymer can be directly blended with PES to prepare PES membranes by a liquid-liquid phase separation technique. The compositions and structure of the PES membranes are characterized by thermogravimetric analysis (TGA), ATR-FTIR, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM); the surface charge density of the modified PES membrane was measured by Zeta-potential; the blood compatibility of the PES membranes was assessed by detecting bovine serum albumin (BSA) and bovine serum fibrinogen (BFG) adsorption, platelet adhesion, activated partial thromboplastin time (APTT), platelet activation, and thrombin-antithrombin III (TAT) generation. The results indicated that the blood compatibility of the modified PES membrane was improved due to the membrane surface modification by blending the amphiphilic block copolymer and the surface segregation of the block copolymer.

  17. A Multifunctional Surface That Simultaneously Balances Hydrophilic Enzyme Catalysis and Hydrophobic Water Repellency.

    Science.gov (United States)

    Lawton, Timothy J; Uzarski, Joshua R; Filocamo, Shaun F

    2016-08-16

    The compatibility of multiple functions at a single interface is difficult to achieve, but is even more challenging when the functions directly counteract one another. This study provides insight into the creation of a simultaneously multifunctional surface formed by balancing two orthogonal functions; water repellency and enzyme catalysis. A partially fluorinated thiol is used to impart bulk hydrophobicity on the surface, and an N-hydroxysuccinimide ester-terminated thiol provides a specific anchoring sites for the covalent enzyme attachment. Different ratios of the two thiols are mixed together to form amphiphilic self-assembled monolayers, which are characterized with polarization-modulation infrared reflection-absorption spectroscopy and contact angle goniometry. The enzyme activity is measured by a fluorescence assay. With the results collected here, specific surface compositions are identified at which the orthogonal functions of water repellency and enzyme catalysis are balanced and exist simultaneously. An understanding of how to effectively balance orthogonal functions at surfaces can be extended to a number of higher-scale applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. The prevalence of mutations in the major hydrophilic region of the surface antigen of hepatitis B virus varies with subgenotype.

    Science.gov (United States)

    Wang, X Y; Harrison, T J; He, X; Chen, Q Y; Li, G J; Liu, M H; Li, H; Yang, J Y; Fang, Z L

    2015-12-01

    Mutations in the major hydrophilic region (MHR) of the surface antigen of hepatitis B virus (HBV) may result in vaccine escape, failure of immunotherapy and antiviral resistance. These mutants may be transmitted and constitute a public health threat. We aimed to determine the prevalence of MHR mutations of HBV in areas of high endemicity in Guangxi, China. HBV surface gene was analysed from 278 HBsAg-positive asymptomatic individuals recruited from Guangxi using cluster sampling. Three genotypes, B, C and I, were identified. The overall prevalence of MHR mutations is 17·6%. The prevalence of MHR mutations in genotype B (15·1%) is not significantly different from that in genotype C (16·4%). However, the prevalence in subgenotype C5 (31·1%) is significantly higher than in subgenotype C2 (13·0%) (χ 2 = 6·997, P subgenotype C5 is significantly higher than in subgenotypes B2 and C2. In total, 7·9% of MHR mutants are escape mutations and 72·1% of MHR mutations produced amino-acid changes in the overlapping polymerase, including resistance mutations to entecavir. Our results suggest that the prevalence of MHR mutations varies with subgenotype. The prevalence of escape mutations and polymerase mutations may be associated with subgenotype.

  19. Dielectric and Mechanical Investigations on the Hydrophilicity and Hydrophobicity of Polyethylene Oxide Modified on a Silicon Surface.

    Science.gov (United States)

    Shang, Jing; Hong, Kunlun; Wang, Tao; Zhu, Dan; Shen, Jian

    2016-11-08

    Polyethylene oxide (PEO) has been widely used in biomedical fields. The antibiofouling property of the PEO-modified surface has been extensively investigated but is far from being fully understood. A series of PEOs with narrowly distributed molecular weight (Mw), synthesized with the technique of high vacuum anionic polymerization, have been successfully grafted onto the surface of silicon wafers. The power-law relationship between the thickness of the monolayer versus the Mw of the grafted PEO shows a scaling of 0.3, indicating compact condensing of the chains. The static contact angles show higher hydrophobicity for the layer of PEO with higher Mw, which can be attributed to the closely packed conformation of the chains with high density. The frequency shift of the contact resonance indicates that the Young's modulus decreases and the loss factor increases with the increase in the Mw of PEO and the thickness of the PEO layers. Dielectric spectroscopy of bare or PEO-grafted wafers in the aqueous solutions reveals an interfacial polarization, which results from compositional and structural changes in the interface layer and depends on temperatures and salt concentrations. At a given grafting density, the PEO chains are swollen in pure water, demonstrating hydrophilic behavior, whereas they collapse in salt solutions, showing hydrophobic characteristics.

  20. Hydrophilic structures for condensation management in appliances

    Science.gov (United States)

    Kuehl, Steven John; Vonderhaar, John J.; Wu, Guolian; Wu, Mianxue

    2016-02-02

    An appliance that includes a cabinet having an exterior surface; a refrigeration compartment located within the cabinet; and a hydrophilic structure disposed on the exterior surface. The hydrophilic structure is configured to spread condensation. The appliance further includes a wicking structure located in proximity to the hydrophilic structure, and the wicking structure is configured to receive the condensation.

  1. Forces acting on a single particle in an evaporating sessile droplet on a hydrophilic surface.

    Science.gov (United States)

    Jung, Jung-yeul; Kim, Young Won; Yoo, Jung Yul; Koo, Junemo; Kang, Yong Tae

    2010-02-01

    The evaporating sessile droplet of a mono/didisperse colloid on a plate is a very useful and handy technique in micro/nano/bioapplications to separate, pattern, and control the particles. Although the fundamental nature of the evaporation phenomena and its applications have been extensively proposed, the crucial forces affecting a single particle motion in an evaporating droplet are not reported yet. To elucidate the impact of various forces including the drag, electrostatic, van der Waals, and surface tension forces on the particle motion in suspension, the magnitudes of them are compared using the scale analysis. In the early stage of the evaporation, in which the contact line is fixed, the motion of a single particle suspended in liquid are mostly affected by drag force. Later, with the incidence of the contact line recession, the surface tension force takes over the control of the single particle motion.

  2. Competition between Hydrophilic and Argyrophilic Interactions in Surface Enhanced Raman Spectroscopy.

    Science.gov (United States)

    Kelly, John T; McClellan, Annie K; Joe, Lynn V; Wright, Ashley M; Lloyd, Lawson T; Tschumper, Gregory S; Hammer, Nathan I

    2016-09-19

    The competition for binding and charge-transfer (CT) from the nitrogen containing heterocycle pyrimidine to either silver or to water in surface enhanced Raman spectroscopy (SERS) is discussed. The correlation between the shifting observed for vibrational normal modes and CT is analyzed both experimentally using Raman spectroscopy and theoretically using electronic structure theory. Discrete features in the Raman spectrum correspond to the binding of either water or silver to each of pyrimidine's nitrogen atoms with comparable frequency shifts. Natural bond orbital (NBO) calculations in each chemical environment reveal that the magnitude of charge transfer from pyrimidine to adjacent silver atoms is only about twice that for water alone. These results suggest that the choice of solvent plays a role in determining the vibrational frequencies of nitrogen containing molecules in SERS experiments.

  3. Fast wettability transition from hydrophilic to superhydrophobic laser-textured stainless steel surfaces under low-temperature annealing

    Science.gov (United States)

    Ngo, Chi-Vinh; Chun, Doo-Man

    2017-07-01

    Recently, the fabrication of superhydrophobic metallic surfaces by means of pulsed laser texturing has been developed. After laser texturing, samples are typically chemically coated or aged in ambient air for a relatively long time of several weeks to achieve superhydrophobicity. To accelerate the wettability transition from hydrophilicity to superhydrophobicity without the use of additional chemical treatment, a simple annealing post process has been developed. In the present work, grid patterns were first fabricated on stainless steel by a nanosecond pulsed laser, then an additional low-temperature annealing post process at 100 °C was applied. The effect of 100-500 μm step size of the textured grid upon the wettability transition time was also investigated. The proposed post process reduced the transition time from a couple of months to within several hours. All samples showed superhydrophobicity with contact angles greater than 160° and sliding angles smaller than 10° except samples with 500 μm step size, and could be applied in several potential applications such as self-cleaning and control of water adhesion.

  4. Fabrication of Silicon Nanobelts and Nanopillars by Soft Lithography for Hydrophobic and Hydrophilic Photonic Surfaces.

    Science.gov (United States)

    Baquedano, Estela; Martinez, Ramses V; Llorens, José M; Postigo, Pablo A

    2017-05-11

    Soft lithography allows for the simple and low-cost fabrication of nanopatterns with different shapes and sizes over large areas. However, the resolution and the aspect ratio of the nanostructures fabricated by soft lithography are limited by the depth and the physical properties of the stamp. In this work, silicon nanobelts and nanostructures were achieved by combining soft nanolithography patterning with optimized reactive ion etching (RIE) in silicon. Using polymethylmethacrylate (PMMA) nanopatterned layers with thicknesses ranging between 14 and 50 nm, we obtained silicon nanobelts in areas of square centimeters with aspect ratios up to ~1.6 and linewidths of 225 nm. The soft lithographic process was assisted by a thin film of SiOx (less than 15 nm) used as a hard mask and RIE. This simple patterning method was also used to fabricate 2D nanostructures (nanopillars) with aspect ratios of ~2.7 and diameters of ~200 nm. We demonstrate that large areas patterned with silicon nanobelts exhibit a high reflectivity peak in the ultraviolet C (UVC) spectral region (280 nm) where some aminoacids and peptides have a strong absorption. We also demonstrated how to tailor the aspect ratio and the wettability of these photonic surfaces (contact angles ranging from 8.1 to 96.2°) by changing the RIE power applied during the fabrication process.

  5. Influences of surface treatments with abrasive paper and sand-blasting on surface morphology, hydrophilicity, mineralization and osteoblasts behaviors of n-CS/PK composite.

    Science.gov (United States)

    Tang, Xiaoming; Huang, Kai; Dai, Jian; Wu, Zhaoying; Cai, Liang; Yang, Lili; Wei, Jie; Sun, Hailang

    2017-04-03

    The surfaces of nano-calcium silicate (n-CS)/polyetheretherketone (PK) composites were treated with abrasive paper and sand-blasting, and the surfaces performances of the as-treated composites were studied. The results showed that the surface roughness, hydrophilicity and mineralization of the simulated body fluid (SBF) of the composites surfaces were significantly improved, and the properties of the composites treated by with sand-blasting were better than those treated with abrasive paper. Moreover, the treated composites significantly promoted osteoblasts responses, such as cell attachment, spreading, proliferation and alkaline phosphatase (ALP) activity, compared to un-treated composites, and the cellular responses to the composites treated with sand-blasting were better than those treated with abrasive paper. The results suggested that surface treatment with sand-blasting was an effective method to greatly improve the surface bioperformances of the n-CS/PK composite, and this treated composite with improved bioactivity and cytocompatibility might be a promising implant material for orthopedic applications.

  6. Mesoscopic Simulations of the Phase Behavior of Aqueous EO 19 PO 29 EO 19 Solutions Confined and Sheared by Hydrophobic and Hydrophilic Surfaces

    KAUST Repository

    Liu, Hongyi

    2012-01-25

    The MesoDyn method is used to investigate associative structures in aqueous solution of a nonionic triblock copolymer consisting of poly(propylene oxide) capped on both ends with poly(ethylene oxide) chains. The effect of adsorbing (hydrophobic) and nonadsorbing (hydrophilic) solid surfaces in contact with aqueous solutions of the polymer is elucidated. The macromolecules form self-assembled structures in solution. Confinement under shear forces is investigated in terms of interfacial behavior and association. The formation of micelles under confinement between hydrophilic surfaces occurs faster than in bulk aqueous solution while layered structures assemble when the polymers are confined between hydrophobic surfaces. Micelles are deformed under shear rates of 1 μs -1 and eventually break to form persistent, adsorbed layered structures. As a result, surface damage under frictional forces is prevented. Overall, this study indicates that aqueous triblock copolymers of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) (Pluronics, EO mPO nEO m) act as a boundary lubricant for hydrophobic surfaces but not for hydrophilic ones. © 2011 American Chemical Society.

  7. Synthesis of Janus-like gold nanoparticles with hydrophilic/hydrophobic faces by surface ligand exchange and their self-assemblies in water.

    Science.gov (United States)

    Iida, Ryo; Kawamura, Hitoshi; Niikura, Kenichi; Kimura, Takashi; Sekiguchi, Shota; Joti, Yasumasa; Bessho, Yoshitaka; Mitomo, Hideyuki; Nishino, Yoshinori; Ijiro, Kuniharu

    2015-04-14

    This study aims at the synthesis of Janus gold nanoparticles (Janus GNPs) with hydrophilic/hydrophobic faces by a simple ligand exchange reaction in an homogeneous system and at the elucidation of the self-assembled structures of the Janus GNPs in water. As hydrophilic surface ligands, we synthesized hexaethylene glycol (E6)-terminated thiolate ligands with C3, C7, or C11 alkyl chains, referred to as E6C3, E6C7, and E6C11, respectively. As a hydrophobic ligand, a butyl-headed thiolate ligand C4-E6C11, in which a C4 alkyl was introduced on the E6C11 terminus, was synthesized. The degree of segregation between the two ligands on the GNPs (5 nm in diameter) was examined by matrix-assisted laser desorption/ionization time-of fright mass spectrometry (MALDI-TOF MS) analysis. We found that the choice of immobilization methods, one-step or two-step addition of the two ligands to the GNP solution, crucially affects the degree of segregation. The two-step addition of a hydrophilic ligand (E6C3) followed by a hydrophobic ligand (C4-E6C11) produced a large degree of segregation on the GNPs, providing Janus-like GNPs. When dispersed in water, these Janus-like GNPs formed assemblies of ∼160 nm in diameter, whereas Domain GNPs, in which the two ligands formed partial domains on the surface, were precipitated even when the molar ratio of the hydrophilic ligand and the hydrophobic ligand on the surface of the NPs was almost 1:1. The assembled structure of the Janus-like GNPs in water was directly observed by pulsed coherent X-ray solution scattering using an X-ray free-electron laser, revealing irregular spherical structures with uneven surfaces.

  8. Modification of the hydrophilic/hydrophobic characteristic of zein film surfaces by contact with oxygen plasma treated PDMS and oleic acid content.

    Science.gov (United States)

    Gezer, P Gizem; Brodsky, Serena; Hsiao, Austin; Liu, G Logan; Kokini, Jozef L

    2015-11-01

    Zein has been widely studied as a biopolymer due to its unique film-forming abilities. Surface properties are of high importance for certain applications which include microfluidics and tissue engineering, as they drastically affect the end result. It is important to develop techniques to modify zein surface properties without compromising bulk material properties. In this study, we developed a facile technique to change the water affinity of zein film surfaces, compatible with patterning techniques via soft lithography. This is achieved by a simple solvent casting technique onto a polydimethylsilohexane (PDMS) substrate that was exposed to oxygen plasma. Water contact angle measurements (WCA) were used to assess the hydrophillicity of zein surfaces and they reached as low as 20°. Atomic force microscopy, optical absorbance and light microscopy were used to study the characteristics of the film and its surface topography. Hydrophilic zein surfaces had higher roughness values compared to hydrophobic ones. Surface roughness, introduced by sandpaper and gratings does not have the same effect as surface chemistry. The amphiphilic nature of plasticizer oleic acid also contributed to the change in the water contact angle of the films. In conclusion, we demonstrated that zein film's surface properties can be controlled by its ability to self-assemble depending on the substrate that it is being cast on.

  9. Surface wettability control by titanium dioxide photo-induced reaction. Super-hydrophilic properties. Sanka chitan ni yoru hikari reiki shinsuika gijutsu. Hikari shokubai chosinsuisei

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, T. (The University of Tokyo, Tokyo (Japan). Research Center for Advanced Science and Technology)

    1999-05-01

    Hydrophilicity results when the surface of titanium dioxide is reduced for the specified oxygen to be replaced by hydroxyl groups. The ease with which such a structural change occurs is subject to variation between titanium dioxide crystal surfaces, and is dependent greatly on the atmosphere. No hydrophilic trend is observed in an atmosphere of oxygen only without moisture and, in darkness without light, hydrophobicity occurs early. Although the contacta angle titanium dioxide with water with stability is not known, yet it is presumed, on the analogy of the case of strontium titanate, that it is in the range of 20-40 degrees. A hydrophilic trend below the range is attrributed to structural changes. The control of surface wettability is one of the basic tasks to fulfill in various kinds of mechanisms and manufacturing processes. The technology of wettability control using a titanium dioxide coating which is quite durable will be applied not only to functions involving defogging, dripproof, and self-cleaning, but also to the control of heat transmission in the mechanism and to the bonding process. (NEDO)

  10. Surface wettability control by titanium dioxide photo-induced reaction. Super-hydrophilic properties; Sanka chitan ni yoru hikari reiki shinsuika gijutsu. Hikari shokubai chosinsuisei

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, T. [The University of Tokyo, Tokyo (Japan). Research Center for Advanced Science and Technology

    1999-05-01

    Hydrophilicity results when the surface of titanium dioxide is reduced for the specified oxygen to be replaced by hydroxyl groups. The ease with which such a structural change occurs is subject to variation between titanium dioxide crystal surfaces, and is dependent greatly on the atmosphere. No hydrophilic trend is observed in an atmosphere of oxygen only without moisture and, in darkness without light, hydrophobicity occurs early. Although the contacta angle titanium dioxide with water with stability is not known, yet it is presumed, on the analogy of the case of strontium titanate, that it is in the range of 20-40 degrees. A hydrophilic trend below the range is attrributed to structural changes. The control of surface wettability is one of the basic tasks to fulfill in various kinds of mechanisms and manufacturing processes. The technology of wettability control using a titanium dioxide coating which is quite durable will be applied not only to functions involving defogging, dripproof, and self-cleaning, but also to the control of heat transmission in the mechanism and to the bonding process. (NEDO)

  11. Fusion peptide P15-CSP shows antibiofilm activity and pro-osteogenic activity when deposited as a coating on hydrophilic but not hydrophobic surfaces.

    Science.gov (United States)

    Li, Xian; Contreras-Garcia, Angel; LoVetri, Karen; Yakandawala, Nandadeva; Wertheimer, Michael R; De Crescenzo, Gregory; Hoemann, Caroline D

    2015-12-01

    In the context of porous bone void filler for oral bone reconstruction, peptides that suppress microbial growth and promote osteoblast function could be used to enhance the performance of a porous bone void filler. We tested the hypothesis that P15-CSP, a novel fusion peptide containing collagen-mimetic osteogenic peptide P15, and competence-stimulating peptide (CSP), a cationic antimicrobial peptide, has emerging properties not shared by P15 or CSP alone. Peptide-coated surfaces were tested for antimicrobial activity toward Streptoccocus mutans, and their ability to promote human mesenchymal stem cell (MSC) attachment, spreading, metabolism, and osteogenesis. In the osteogenesis assay, peptides were coated on tissue culture plastic and on thin films generated by plasma-enhanced chemical vapor deposition to have hydrophilic or hydrophobic character (water contact angles 63°, 42°, and 92°, respectively). S. mutans planktonic growth was specifically inhibited by CSP, whereas biofilm formation was inhibited by P15-CSP. MSC adhesion and actin stress fiber formation was strongly enhanced by CSP, P15-CSP, and fibronectin coatings and modestly enhanced by P15 versus uncoated surfaces. Metabolic assays revealed that CSP was slightly cytotoxic to MSCs. MSCs developed alkaline phosphatase activity on all surfaces, with or without peptide coatings, and consistently deposited the most biomineralized matrix on hydrophilic surfaces coated with P15-CSP. Hydrophobic thin films completely suppressed MSC biomineralization, consistent with previous findings of suppressed osteogenesis on hydrophobic bioplastics. Collective data in this study provide new evidence that P15-CSP has unique dual capacity to suppress biofilm formation, and to enhance osteogenic activity as a coating on hydrophilic surfaces.

  12. Hydrophobic-hydrophilic monolithic dual-phase layer for two-dimensional thin-layer chromatography coupled with surface-enhanced Raman spectroscopy detection.

    Science.gov (United States)

    Zheng, Binxing; Liu, Yanhua; Li, Dan; Chai, Yifeng; Lu, Feng; Xu, Jiyang

    2015-08-01

    Hydrophobic-hydrophilic monolithic dual-phase plates have been prepared by a two-step polymerization method for two-dimensional thin-layer chromatography of low-molecular-weight compounds, namely, several dyes. The thin 200 μm poly(glycidyl methacrylate-co-ethylene dimethacrylate) layers attached to microscope glass plates were prepared using a UV-initiated polymerization method within a simple glass mold. After cutting and cleaning the specific area of the layer, the reassembled mold was filled with a polymerization mixture of butyl methacrylate and ethylene dimethacrylate and subsequently irradiated with UV light. During the second polymerization process, the former layer was protected from the UV light with a UV mask. After extracting the porogens and hydrolyzing the poly(glycidyl methacrylate-co-ethylene dimethacrylate) area, these two-dimensional layers were used to separate a mixture of dyes with great difference in their polarity using reversed-phase chromatography mode within the hydrophobic layer and then hydrophilic interaction chromatography mode along the hydrophilic area. In the latter dimension only the specific spot was developed further. Detection of the separated dyes could be achieved with surface-enhanced Raman spectroscopy.

  13. Wetting state transition on hydrophilic microscale rough surface%亲水性微观粗糙表面润湿状态转变性能研究

    Institute of Scientific and Technical Information of China (English)

    刘思思; 张朝辉; 何建国; 周杰; 尹恒洋

    2013-01-01

    以亲水性微观粗糙表面上不同几何形貌及分布的微柱阵列为对象,讨论了液滴在亲水性粗糙表面上的润湿过程以及润湿状态的转变阶段。从能量角度分别考察了微观粗糙结构几何形貌及分布、微柱几何参数、固体表面亲水性、接触角滞后作用等因素对液滴润湿状态转变的影响规律。研究发现:在亲水粗糙表面,正方形微柱呈正六边形阵列分布时,液滴更容易形成稳定的Cassie状态,或者液滴仅发生Cassie状态向中间浸润状态的转变;与此同时,减小微柱间距、增大方柱宽度或圆柱直径、增大微柱高度、增强固体表面的亲水性将有利于液滴处于稳定的Cassie状态,或阻止润湿状态向伪-Wenzel或Wenzel状态转变;然而,当液滴处于Cassie状态时,较小的固-液界面面积分数或减弱固体表面亲水性能均有利于增大液滴的表观接触角,因此在亲水表面设计粗糙结构时应综合考虑润湿状态稳定性和较大表观接触角两方面因素;此外,接触角滞后作用对于液滴状态的稳定性以及疏水性能的实现具有相反作用的影响。研究结果为液滴在亲水表面获得稳定Cassie状态的粗糙结构设计方法提供了理论依据。%The wetting process and the wetting state transition stages are studied on hydrophilic rough surfaces covered with microscale pillar arrays of different geometrical morphologies and distributions. The effects of geometrical morphology, distribution, parameters, hydrophilicity, and contact angle hysteresis of pillar arrays on wetting state transition are analyzed by an energy method. The results indicate that on the hydrophilic rough surface covered with hexagonal arrays of square pillars, the water droplet tends to stay in a stable Cassie state, or the wetting state transits only from a Cassie state to an intermediate state. Moreover, smaller pillar interval, larger square pillar width or

  14. Surface hydrophilic modification of acrylonitrile-butadiene-styrene terpolymer by poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate): Preparation, characterization, and properties studies

    Science.gov (United States)

    Chen, Tingting; Zhang, Jun

    2016-12-01

    Surface hydrophilic modified acrylonitrile-butadiene-styrene (ABS) terpolymer was prepared by melt blending with poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) (PETG) random copolymer as the modifier. Attenuated total reflectance-Fourier transform-infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) were used for surface analysis. Through the contact angle measurement, the relationship between surface properties of the ABS/PETG blends and PETG content was investigated. Scanning electron microscope (SEM) and dynamical mechanical thermal analysis (DMTA) were used to characterize interface morphology and compatibility of the blends. The effect of PETG content on the mechanical and rheological properties was examined. The ATR-FTIR and XPS analysis suggested that the hydrophilic groups were enriched on the surface with increasing PETG content in the blend. The decrease of the water contact angle and the increase of the polarity for the blends with increasing PETG content indicated that the hydrophilic property of the blends was enhanced with increasing PETG content. The ABS/PETG blends were partially miscible. And the blends with ≤50 wt% PETG had better compatibility than the blends with above 50 wt% PETG. It was clear that below 50 wt% PETG, the PETG phase was dispersed in spherical form and the ABS phase was continuous. Above 50 wt% PETG, the PETG phase became continuous and the ABS phase was dispersed in irregular form. Moreover, the tensile strength and flexural strength of the blends were enhanced with increasing PETG content. The flexural modulus almost remained constant. And the impact strength was decreased when the content of PETG was increasing.

  15. Hybrid selective surface hydrophilization and froth flotation separation of hazardous chlorinated plastics from E-waste with novel nanoscale metallic calcium composite.

    Science.gov (United States)

    Mallampati, Srinivasa Reddy; Heo, Je Haeng; Park, Min Hee

    2016-04-05

    Treatment by a nanometallic Ca/CaO composite has been found to selectively hydrophilize the surface of polyvinyl chloride (PVC), enhancing its wettability and thereby promoting its separation from E-waste plastics by means of froth flotation. The treatment considerably decreased the water contact angle of PVC, by about 18°. The SEM images of the PVC plastic after treatment displayed significant changes in their surface morphology compared to other plastics. The SEM-EDS results reveal that a markedly decrease of [Cl] concentration simultaneously with dramatic increase of [O] on the surface of the PCV samples. XPS results further confirmed an increase of hydrophilic functional groups on the PVC surface. Froth flotation at 100rpm mixing speed was found to be optimal, separating 100% of the PVC into a settled fraction of 96.4% purity even when the plastics fed into the reactor were of nonuniform size and shape. The total recovery of PVC-free plastics in E-waste reached nearly 100% in the floated fraction, significantly improved from the 20.5wt% of light plastics that can be recovered by means of conventional wet gravity separation. The hybrid method of nanometallic Ca/CaO treatment and froth flotation is effective in the separation of hazardous chlorinated plastics from E-waste plastics. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Hydrophilic Cu{sub 2}O nanostructured thin films prepared by facile spin coating method: Investigation of surface energy and roughness

    Energy Technology Data Exchange (ETDEWEB)

    Eskandari, A.; Sangpour, P., E-mail: sangpour@merc.ac.ir; Vaezi, M.R.

    2014-10-15

    We demonstrate a facile, uniform and large scale chemical route to synthesize the cuprous oxide (Cu{sub 2}O) nanostructured thin film via spin coating technique. The samples were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), simultaneous thermal analysis (STA) and UV–visible spectra. Based on the results, the transparent Cu{sub 2}O thin films were formed at the low temperature (275 °C) due to employed N{sub 2} atmosphere in annealing processes. The average roughness is decreased by increasing the number of layers from 11 to 6.4 nm for 1 and 5 times of successive deposition of copper oxide, respectively. Afterward, by increasing the cycle of deposition, the roughness increased (∼87%) owning to the transformation of the growth mechanism of thin films from Volmer–Weber to Stranski–Krastanov mode. Moreover, the prepared films were extremely hydrophilic with water contact angle about 45° and surface energy 54.26 mJ m{sup −2} after 10-cycle coating. The smooth and low energy surface with this technique could be tailored for photoelectrochemical applications such as water splitting. - Highlights: • Hydrophilic Cu{sub 2}O nanostructured thin films synthesized by a facile method. • By increasing the cycle of deposition, finer particles obtained. • Surface energy and contact angle strongly depend on the film formation mechanism. • Transformation of the thin films growth mechanism was studied.

  17. Effects of surface hydrophilicity and microtopography on early stages of soft and hard tissue integration at non-submerged titanium implants: an immunohistochemical study in dogs.

    Science.gov (United States)

    Schwarz, Frank; Ferrari, Daniel; Herten, Monika; Mihatovic, Ilja; Wieland, Marco; Sager, Martin; Becker, Jürgen

    2007-11-01

    The aim of the present study was to investigate the effects of surface hydrophilicity and microtopography on soft and hard tissue integration at non-submerged titanium implants. Implantation of conventional sand-blasted large grit and acid-etched (SLA) and chemically modified SLA (modSLA) titanium implants with differently structured transmucosal surfaces (SLA implants: machined [M-SLA] or SLA [SLA-SLA]; modSLA implants: mod acid-etched [modA] [modA-modSLA] or modSLA [modSLA-modSLA]) was performed bilaterally in the upper and lower jaws of 15 beagle dogs. The animals were sacrificed after 1, 4, 7, 14, or 28 days. Tissue reactions were assessed histomorphometrically and immunohistochemically using monoclonal antibodies to transglutaminase II (angiogenesis) and osteocalcin. Although the junctional epithelium commonly was separated from M-SLA and SLA-SLA implants by a gap, the epithelial cells appeared to be in close contact with modA-modSLA surfaces after 14 days of healing. Moreover, modA-modSLA and modSLA-modSLA groups showed a well-vascularized subepithelial connective tissue exhibiting collagen fibers that started to extend and attach partially perpendicular to the implant surface. The highest and statistically significant mean bone-to-implant contact areas were observed in the modA-modSLA and modSLA-modSLA groups at days 7, 14, and 28. Within the limits of this study, it may be concluded that soft and hard tissue integration was influenced mainly by surface hydrophilicity rather than by microtopography.

  18. The fabrication of stable superhydrophobic surfaces using a thin Au/Pd coating over a hydrophilic 3C-SiC nanorod network

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Afzal [Materials Science Centre, IIT Kharagpur, West Bengal 721302 (India); Sohail, Shiraz [Department of Electrical Engineering, IIT Kharagpur, West Bengal 721302 (India); Jacob, Chacko, E-mail: cxj14_holiday@yahoo.com [Materials Science Centre, IIT Kharagpur, West Bengal 721302 (India)

    2015-10-30

    Graphical abstract: - Highlights: • Superhydrophobicity achieved using a metallic coating on a nanorod surface of 3C-SiC. • Hierarchical nanostructures made up of nanorod network with thin Au/Pd coating. • Surface adsorbed organic contaminants further lowered the surface energy. • High water contact angle (160°) and very low sliding angle (<5°) of a water droplet. • Reproducibility of the results was checked over a period of 14 months. - Abstract: In this work, it has been demonstrated that for hydrophilic materials, like SiC, etc., superhydrophobicity can be achieved by coating them with a material like Au/Pd with surface adsorbed organic contaminants, rather than modifying them by fluoropolymers as is usually done. Dense and randomly aligned 3C-SiC nanorods were grown in a cold-wall APCVD reactor using Ni as a catalyst which formed a network of micro/nano air pockets and exhibited superhydrophobic behavior when modified by an Au/Pd metal alloy coating by forming hierarchical nanostructures with surface adsorbed organic contaminants. A high water contact angle (160°), very low sliding angle (<5°), rebounding and a rubber ball-like behavior of a water droplet were observed on such a metal (Au/Pd) modified surface of 3C-SiC nanorods. The durability of the surface and reproducibility of the results was checked over a period of about 14 months under ambient atmosphere at room temperature, which demonstrates the long term stability of these superhydrophobic surfaces.

  19. Improved Sensitization of Zinc Oxide Nanorods by Cadmium Telluride Quantum Dots through Charge Induced Hydrophilic Surface Generation

    Directory of Open Access Journals (Sweden)

    Karthik Laxman

    2014-01-01

    Full Text Available This paper reports on UV-mediated enhancement in the sensitization of semiconductor quantum dots (QDs on zinc oxide (ZnO nanorods, improving the charge transfer efficiency across the QD-ZnO interface. The improvement was primarily due to the reduction in the interfacial resistance achieved via the incorporation of UV light induced surface defects on zinc oxide nanorods. The photoinduced defects were characterized by XPS, FTIR, and water contact angle measurements, which demonstrated an increase in the surface defects (oxygen vacancies in the ZnO crystal, leading to an increase in the active sites available for the QD attachment. As a proof of concept, a model cadmium telluride (CdTe QD solar cell was fabricated using the defect engineered ZnO photoelectrodes, which showed ∼10% increase in photovoltage and ∼66% improvement in the photocurrent compared to the defect-free photoelectrodes. The improvement in the photocurrent was mainly attributed to the enhancement in the charge transfer efficiency across the defect rich QD-ZnO interface, which was indicated by the higher quenching of the CdTe QD photoluminescence upon sensitization.

  20. Investigation on the hysteretic force of droplet on hydrophilic and hydrophobic surface%亲/疏水表面上液滴滞后阻力的研究

    Institute of Scientific and Technical Information of China (English)

    秦亮; 刘天庆

    2012-01-01

    表面上液滴欲移动时所表现出的滞后现象尚未在理论上得到完全解决,其中液滴所受到的滞后阻力的分析和计算是定量描述此滞后现象的关键问题之一。本文应用高速摄像,实验研究了亲/疏水表面上液滴的滞后阻力,并依据相应的实验数据对滞后阻力进行了分析和验证。结果表明:液滴在亲水和疏水表面上运动时所受到的滞后阻力分别与铺展功和黏附功相对应。滞后阻力反映了液滴在亲/疏水表面上出现滞后现象的本质,同时对于进一步研究接触角滞后提供了理论基础。%The hysteresis phenomenon of droplet moving on surfaces has not yet been fully explained theoretically,and the analysis and calculation of the hysteretic force of a droplet is one of the key points to quantitatively describe the hysteresis phenomenon.By means of high speed camera,the hysteretic force of a droplet on hydrophilic and hydrophobic surface was studied and further verified by experimental data.The results indicate that the hysteretic forces of droplets moving on hydrophilic and hydrophobic surfaces are corresponding to spreading and adhesion respectively.The hysteretic force can explain hysteresis phenomenon and provides a theory basis for furthering research on contact angle hysteresis(CAH).

  1. Modeling the Interaction between AFM Tips and Pinned Surface Nanobubbles.

    Science.gov (United States)

    Guo, Zhenjiang; Liu, Yawei; Xiao, Qianxiang; Schönherr, Holger; Zhang, Xianren

    2016-01-26

    Although the morphology of surface nanobubbles has been studied widely with different AFM modes, AFM images may not reflect the real shapes of the nanobubbles due to AFM tip-nanobubble interactions. In addition, the interplay between surface nanobubble deformation and induced capillary force has not been well understood in this context. In our work we used constraint lattice density functional theory to investigate the interaction between AFM tips and pinned surface nanobubbles systematically, especially concentrating on the effects of tip hydrophilicity and shape. For a hydrophilic tip contacting a nanobubble, its hydrophilic nature facilitates its departure from the bubble surface, displaying a weak and intermediate-range attraction. However, when the tip squeezes the nanobubble during the approach process, the nanobubble shows an elastic effect that prevents the tip from penetrating the bubble, leading to a strong nanobubble deformation and repulsive interactions. On the contrary, a hydrophobic tip can easily pierce the vapor-liquid interface of the nanobubble during the approach process, leading to the disappearance of the repulsive force. In the retraction process, however, the adhesion between the tip and the nanobubble leads to a much stronger lengthening effect on nanobubble deformation and a strong long-range attractive force. The trends of force evolution from our simulations agree qualitatively well with recent experimental AFM observations. This favorable agreement demonstrates that our model catches the main intergradient of tip-nanobubble interactions for pinned surface nanobubbles and may therefore provide important insight into how to design minimally invasive AFM experiments.

  2. Hydrological land surface modelling

    DEFF Research Database (Denmark)

    Ridler, Marc-Etienne Francois

    to imperfect model forecasts. It remains a crucial challenge to account for system uncertainty, so as to provide model outputs accompanied by a quantified confidence interval. Properly characterizing and reducing uncertainty opens-up the opportunity for risk-based decision-making and more effective emergency...... and disaster management. The objective of this study is to develop and investigate methods to reduce hydrological model uncertainty by using supplementary data sources. The data is used either for model calibration or for model updating using data assimilation. Satellite estimates of soil moisture and surface...... temperature are explored in a multi-objective calibration experiment to optimize the parameters in a SVAT model in the Sahel. The two satellite derived variables were effective at constraining most land-surface and soil parameters. A data assimilation framework is developed and implemented with an integrated...

  3. Influence of chitosan and polycarbophil on permeation of a model hydrophilic drug into the urinary bladder wall.

    Science.gov (United States)

    Grabnar, I; Bogataj, M; Mrhar, A

    2003-04-30

    Influence of dispersions of mucoadhesive polymers chitosan and polycarbophil on permeability properties of urinary bladder was investigated in vitro on isolated porcine urinary bladder. Pipemidic acid as a model hydrophilic drug was used. Its distribution in the bladder wall was determined from actual tissue concentrations by a method based on sectioning of frozen tissue and extraction of tissue slices. Pipemidic acid tissue concentration versus tissue depth profiles were evaluated by a diffusion model assuming constant diffusion coefficient. Increase in bladder wall permeability was observed in the presence of both polymers. Apparent permeability (mean+/-S.D.) of urinary bladder wall was increased 2.7+/-2.9 and 2.8+/-2.0 times for chitosan, and 2.3+/-2.0 and 4.3+/-4.2 times for polycarbophil at 0.5 and 1.0%, w/v polymer concentration, respectively. This increase is a consequence of the increased permeability of urothelium. These findings support investigations on application of chitosan and polycarbophil in development of mucoadhesive intravesical drug delivery systems. Experimental model may be applied to evaluate the results of experiments with drugs used in intravesical therapy.

  4. Improvement of Surface Wettability and Hydrophilization of Poly-paraphenylene benzobisoxazole Fiber with Fibrillation Combined Oxygen Plasma Treatment

    OpenAIRE

    Xiwen Wang; Jian Hu,; Yun Liang

    2012-01-01

    A new surface modification method fibrillation combined with oxygen plasma treatment to improve the wettability and hydrophily of PBO fiber was studied in this paper. The surface chemical structure and morphology of PBO fiber were characterized by the methods of FTIR, XPS and SEM. The wettability and hydrophlic characters changes on the surface were evaluated by the dynamic contact angle system and image analysis. The results show that the increase surface roughness by fibrillation could impr...

  5. Development of a Physiologically Based Computational Kidney Model to Describe the Renal Excretion of Hydrophilic Agents in Rats

    Science.gov (United States)

    Niederalt, Christoph; Wendl, Thomas; Kuepfer, Lars; Claassen, Karina; Loosen, Roland; Willmann, Stefan; Lippert, Joerg; Schultze-Mosgau, Marcus; Winkler, Julia; Burghaus, Rolf; Bräutigam, Matthias; Pietsch, Hubertus; Lengsfeld, Philipp

    2013-01-01

    A physiologically based kidney model was developed to analyze the renal excretion and kidney exposure of hydrophilic agents, in particular contrast media, in rats. In order to study the influence of osmolality and viscosity changes, the model mechanistically represents urine concentration by water reabsorption in different segments of kidney tubules and viscosity dependent tubular fluid flow. The model was established using experimental data on the physiological steady state without administration of any contrast media or drugs. These data included the sodium and urea concentration gradient along the cortico-medullary axis, water reabsorption, urine flow, and sodium as well as urea urine concentrations for a normal hydration state. The model was evaluated by predicting the effects of mannitol and contrast media administration and comparing to experimental data on cortico-medullary concentration gradients, urine flow, urine viscosity, hydrostatic tubular pressures and single nephron glomerular filtration rate. Finally the model was used to analyze and compare typical examples of ionic and non-ionic monomeric as well as non-ionic dimeric contrast media with respect to their osmolality and viscosity. With the computational kidney model, urine flow depended mainly on osmolality, while osmolality and viscosity were important determinants for tubular hydrostatic pressure and kidney exposure. The low diuretic effect of dimeric contrast media in combination with their high intrinsic viscosity resulted in a high viscosity within the tubular fluid. In comparison to monomeric contrast media, this led to a higher increase in tubular pressure, to a reduction in glomerular filtration rate and tubular flow and to an increase in kidney exposure. The presented kidney model can be implemented into whole body physiologically based pharmacokinetic models and extended in order to simulate the renal excretion of lipophilic drugs which may also undergo active secretion and reabsorption

  6. Hydrological land surface modelling

    DEFF Research Database (Denmark)

    Ridler, Marc-Etienne Francois

    Recent advances in integrated hydrological and soil-vegetation-atmosphere transfer (SVAT) modelling have led to improved water resource management practices, greater crop production, and better flood forecasting systems. However, uncertainty is inherent in all numerical models ultimately leading...... and disaster management. The objective of this study is to develop and investigate methods to reduce hydrological model uncertainty by using supplementary data sources. The data is used either for model calibration or for model updating using data assimilation. Satellite estimates of soil moisture and surface...... hydrological and tested by assimilating synthetic hydraulic head observations in a catchment in Denmark. Assimilation led to a substantial reduction of model prediction error, and better model forecasts. Also, a new assimilation scheme is developed to downscale and bias-correct coarse satellite derived soil...

  7. Rapid Hydrophilization of Model Polyurethane/Urea (PURPEG Polymer Scaffolds Using Oxygen Plasma Treatment

    Directory of Open Access Journals (Sweden)

    Rok Zaplotnik

    2016-04-01

    Full Text Available Polyurethane/urea copolymers based on poly(ethylene glycol (PURPEG were exposed to weakly ionized, highly reactive low-pressure oxygen plasma to improve their sorption kinetics. The plasma was sustained with an inductively coupled radiofrequency generator operating at various power levels in either E-mode (up to the forward power of 300 W or H-mode (above 500 W. The treatments that used H-mode caused nearly instant thermal degradation of the polymer samples. The density of the charged particles in E-mode was on the order of 1016 m−3, which prevented material destruction upon plasma treatment, but the density of neutral O-atoms in the ground state was on the order of 1021 m−3. The evolution of plasma characteristics during sample treatment in E-mode was determined by optical emission spectroscopy; surface modifications were determined by water adsorption kinetics and X-ray photoelectron spectroscopy; and etching intensity was determined by residual gas analysis. The results showed moderate surface functionalization with hydroxyl and carboxyl/ester groups, weak etching at a rate of several nm/s, rather slow activation down to a water contact angle of 30° and an ability to rapidly absorb water.

  8. Surface modification of poly(ethylene terephthalate) angioplasty balloons with a hydrophilic poly(acrylamide-co-ethylene glycol) interpenetrating polymer network coating.

    Science.gov (United States)

    Park, S; Bearinger, J P; Lautenschlager, E P; Castner, D G; Healy, K E

    2000-09-01

    An interpenetrating polymer network (IPN) of poly(acrylamide-co-ethylene glycol) (p(AAm-co-EG)) hydrogel was covalently grafted to polyethylene terephthalate (PET) angioplasty balloons to increase surface hydrophilicity and improve lubricity. A 2-step graft polymerization protocol was followed to first polymerize and cross-link acrylamide onto the substrate with a photosensitizer and/or oxygen plasma pretreatment. The effects of varying photo-initiation and plasma exposure times were investigated separately and conjunctively using water contact angles to obtain optimal coating deposition parameters. A poly(ethylene glycol) network was then grafted by swelling the preexisting polyacrylamide network to allow inter-diffusion of the monomer and cross-linker, which were then polymerized by photo-initiation. When the photo-initiation time was long enough to reach near gelation, pretreatment of PET with oxygen plasma did not offer significant benefit. X-ray photoelectron spectroscopy confirmed the presence of both polymer layers, and composition depth profiles supported the assessment that an interpenetrating network was formed. Tensile testing and application of Weibull statistics on unmodified and modified films indicated that the surface modification approach did not significantly alter the mechanical integrity of the material. These findings indicate that a p(AAm-co-EG) coating can be effectively deposited on PET surfaces without compromising the structural integrity of the substrate.

  9. Predictive Surface Complexation Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Sverjensky, Dimitri A. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Earth and Planetary Sciences

    2016-11-29

    Surface complexation plays an important role in the equilibria and kinetics of processes controlling the compositions of soilwaters and groundwaters, the fate of contaminants in groundwaters, and the subsurface storage of CO2 and nuclear waste. Over the last several decades, many dozens of individual experimental studies have addressed aspects of surface complexation that have contributed to an increased understanding of its role in natural systems. However, there has been no previous attempt to develop a model of surface complexation that can be used to link all the experimental studies in order to place them on a predictive basis. Overall, my research has successfully integrated the results of the work of many experimentalists published over several decades. For the first time in studies of the geochemistry of the mineral-water interface, a practical predictive capability for modeling has become available. The predictive correlations developed in my research now enable extrapolations of experimental studies to provide estimates of surface chemistry for systems not yet studied experimentally and for natural and anthropogenically perturbed systems.

  10. Measurements on hydrophobic and hydrophilic surfaces using a porous gamma alumina nanoparticle aggregate mounted on Atomic Force Microscopy cantilevers

    NARCIS (Netherlands)

    Das, Theerthankar; Becker, Thomas; Nair, Balagopal N.

    2010-01-01

    Atomic Force Microscopy (AFM) measurements are extensively used for a detailed understanding of molecular and surface forces. In this study, we present a technique for measuring such forces, using an AFM cantilever attached with a porous gamma alumina nanoparticle aggregate. The modified cantilever

  11. High-performance liquid chromatography as a technique to determine protein adsorption onto hydrophilic/hydrophobic surfaces.

    Science.gov (United States)

    Huang, Tongtong; Anselme, Karine; Sarrailh, Segolene; Ponche, Arnaud

    2016-01-30

    The purpose of this study is to evaluate the potential of simple high performance liquid chromatography (HPLC) setup for quantification of adsorbed proteins on various type of plane substrates with limited area (hydrophobic (polydimethylsiloxane: PDMS) surfaces, kinetics of adsorption were determined and amounts of adsorbed bovine serum albumin, myoglobin and lysozyme were obtained: as expected for each protein, the amount adsorbed at the plateau on glass (between 0.15 μg/cm(2) and 0.4 μg/cm(2)) is lower than for hydrophobic PDMS surfaces (between 0.45 μg/cm(2) and 0.8 μg/cm(2)). These results were consistent with bicinchoninic acid protein determination. According to ICH guidelines, both Reversed Phase and Size Exclusion HPLC can be validated for quantification of adsorbed protein. However, we consider the size exclusion approach more interesting in this field because additional informations can be obtained for aggregative proteins. Indeed, monomer, dimer and oligomer of bovine serum albumin (BSA) were observed in the chromatogram. On increasing the temperature, we found a decrease of peak intensity of bovine serum albumin as well as the fraction of dimer and oligomer after contact with PDMS and glass surface. As the surface can act as a denaturation parameter, these informations can have a huge impact on the elucidation of the interfacial behavior of protein and in particular for aggregation processes in pharmaceutical applications.

  12. Hydrophilic behavior of graphene and graphene-based materials.

    Science.gov (United States)

    Accordino, Sebastián R; Montes de Oca, Joan Manuel; Rodriguez Fris, J Ariel; Appignanesi, Gustavo A

    2015-10-21

    Graphene and the graphene-based materials like graphite, carbon nanotubes, and fullerenes are not only usually regarded as hydrophobic but also have been widely employed as paradigms for the investigation of the behavior of water under nonpolar confinement, a question of major concern for fields ranging from biology to materials design. However, some experimental and theoretical insights seem to contradict, at least partially, such a picture. In this work, we will provide firm evidence for a neat hydrophilic nature of graphene surfaces. Our molecular dynamics studies will demonstrate that parallel graphene sheets present a strong tendency to remain fully hydrated for moderately long times (even when the equilibrium state is indeed the collapse of the plates), and thus, they are less prone to self-assembly than model hydrophobic surfaces we shall employ as control which readily undergo a hydrophobic collapse. Potential of mean force calculations will indeed make evident that the solvent exerts a repulsive contribution on the self-assembly of graphene surfaces. Moreover, we shall also quantify graphene hydrophilicity by means of the calculation of water density at two pressures and water density fluctuations. This latter study has never been performed on graphene and represents a means both to confirm and to quantify its neat hydrophilic behavior. We shall also make evident the relevance of the mildly attractive water-carbon interactions, since their artificial weakening will be shown to revert from typically hydrophilic to typically hydrophobic behavior.

  13. Determination of functionalized gold nanoparticles incorporated in hydrophilic and hydrophobic microenvironments by surface modification of quartz crystal microbalance

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Tsui-Hsun [Institute of Biomedical Engineering, College of Engineering, College of Medicine, National Taiwan University, Taipei, Taiwan, ROC (China); Institute of Medical Mechatronics, Chang Gung University, Tao-Yuan, Taiwan, ROC (China); Liao, Shu-Chuan [Center of Thin Film Technologies and Applications, Mingchi University of Technology, Taipei, Taiwan, ROC (China); Chen, Ying-Fang [Department of Dentistry, Yun-Lin Branch, National Taiwan University Hospital, Dou-Liu, Yun-Lin, Taiwan, ROC (China); Huang, Yi-You [Institute of Biomedical Engineering, College of Engineering, College of Medicine, National Taiwan University, Taipei, Taiwan, ROC (China); Wei, Yi-Syuan [Department of Materials Engineering, Tatung University, 40 Zhongshan North Road, 3rd Section, Taipei 104, Taiwan, ROC (China); Tu, Shu-Ju, E-mail: sjt@cgu.edu.tw [Department of Medical Imaging and Radiological Sciences, Chang Gung University, 259 Wen-Hwa, 1st Road, Kwei-Shan, Tao-Yuan 133, Taiwan, ROC (China); Chen, Ko-Shao, E-mail: kschen@ttu.edu.tw [Department of Materials Engineering, Tatung University, 40 Zhongshan North Road, 3rd Section, Taipei 104, Taiwan, ROC (China)

    2013-06-01

    In this study, plasma deposition methods were used to immobilize Au electrode of a quartz crystal microbalance (QCM) to create different microenvironments for mass measurement of various modified Au nanoparticles (AuNPs). AuNPs were modified by 11-mercaptoundecanoic acid (MUA) and 1-decanethiol (DCT) for potential applications to drug release, protective coatings, and immunosensors. We aimed to develop a highly sensitive and reliable method to quantify the mass of various modified AuNPs. The surface of AuNPs and Au electrode was coated with polymer films, as determined by Fourier transform infrared spectroscopy and atomic force microscopy. Measurements obtained for various AuNPs and the plasma-treated surface of the Au electrode were compared with those obtained for an untreated Au electrode. According to the resonant frequency shift of QCM, a linear relationship was observed that significantly differed for AuNPs, MUA-AuNPs, and DCT-AuNPs (R{sup 2} range, 0.94–0.965, 0.934–0.972, and 0.874–0.9514, respectively). Compared to inductively coupled plasma and micro-computerized tomography, the QCM method with plasma treatment has advantages of real-time monitoring, greater sensitivity, and lower cost. Our results demonstrate that surface modifications measured by a QCM system for various modified AuNPs were reliable.

  14. Improvement of 3D Polyester Fabric Surface with Nano Beta-Cyclodextrin and Hydrophilic Silicone and Microemulsion Softeners

    Directory of Open Access Journals (Sweden)

    M. M. Jolaei

    2016-12-01

    Full Text Available Modifying of polyester spacer fabric by β-Cyclodextrin may create new characteristics in the product. Using different siloxane including amino ethyl amino propyl polydimethylsiloxane and polyether amino functional siloxane can produce appropriate softness and lead to relative stability of β-CD on polyester fabric. In this research different concentration of siloxane compounds as a softener, and β- CD as a modifier are applied and some of the properties of the fabric including weight change, regain, water drop absorption time on fabric surface, chrome ion absorption and reactive dye absorption are studied. Also morphology of fabric surface has been examined by SEM images and chemical structure by FT-IR. We have also studied washing durability of the modified product after 10 times of washing. The results show that increasing of concentration of softener and β-CD leads to obtain a higher gain modification. In comparison of two different based softeners the amino ethyl amino propyl polydimethylsiloxane (AEAP- Silicon indicates a better durability than the polyether amino functional siloxane (PEA-Silicon.

  15. Microfiltration of different surface waters with/without coagulation: clear correlations between membrane fouling and hydrophilic biopolymers.

    Science.gov (United States)

    Kimura, Katsuki; Tanaka, Ken; Watanabe, Yoshimasa

    2014-02-01

    Although low-pressure membranes (microfiltration (MF) or ultrafiltration (UF)) have become viable options for drinking water treatment, problems caused by membrane fouling must still be addressed. The objective of this study was to compare five different surface waters and to identify a relevant index of water quality that can be used for prediction of the fouling potential of the water. Bench-scale filtration tests were carried out with commercially available hollow-fiber MF membranes. Fairly long-term (a few days) filtrations in the constant-flow mode were carried out with automatic backwash. Membrane fouling in this study was shown to be irreversible as a result of the periodic backwash carried out throughout of the operation. Easily accessible indexes of water quality including dissolved organic carbon (DOC), UV absorbance, Ca concentration and turbidity could not explain the degree of fouling encountered in the filtration tests. Fluorescence excitation-emission matrix (EEM) could provide information on the presence of protein-like substances in water, and peaks for protein showed some correlation with the membrane fouling. Biopolymer (characterized by high molecular weights and insensitivity to UV light absorption) concentrations in the five waters determined by liquid chromatography with organic carbon detection (LC-OCD) exhibited an excellent correlation with the fouling rates. Coagulation with polyaluminum chloride could mitigate membrane fouling in all cases. The extent of fouling seen with coagulated waters was also correlated with biopolymer concentrations. The relationship between biopolymer concentrations and the fouling rates established for the raw waters could also be applied to the coagulated waters. These results suggested that the contribution of biopolymers to membrane fouling in the present study was significant, an observation that was supported by the analysis of foulants extracted at the termination of each test. Biopolymer concentrations

  16. Heterogeneous nucleation of ice on model carbon surfaces

    Science.gov (United States)

    Molinero, V.; Lupi, L.; Hudait, A.

    2014-12-01

    Carbonaceous particles account for 10% of the particulate matter in the atmosphere. The experimental investigation of heterogeneous freezing of water droplets by carbonaceous particles reveals widespread ice freezing temperatures. The origin of the soot and its oxidation and aging modulate its ice nucleation ability, however, it is not known which structural and chemical characteristics of soot account for the variability in ice nucleation efficiency. We find that atomically flat carbon surfaces promote heterogeneous nucleation of ice, while molecularly rough surfaces with the same hydrophobicity do not. We investigate a large set of graphitic surfaces of various dimensions and radii of curvature consistent with those of soot in experiments, and find that variations in nanostructures alone could account for the spread in the freezing temperatures of ice on soot in experiments. A characterization of the nanostructure of soot is needed to predict its ice nucleation efficiency. Atmospheric oxidation and aging of soot modulates its ice nucleation ability. It has been suggested that an increase in the ice nucleation ability of aged soot results from an increase in the hydrophilicity of the surfaces upon oxidation. Oxidation, however, also impacts the nanostructure of soot, making it difficult to assess the separate effects of soot nanostructure and hydrophilicity in experiments. We investigate the effect of changes in hydrophilicity of model graphitic surfaces on the freezing temperature of ice. Our results indicate that the hydrophilicity of the surface is not in general a good predictor of ice nucleation ability. We find a correlation between the ability of a surface to promote nucleation of ice and the layering of liquid water at the surface. The results of this work suggest that ordering of liquid water in contact with the surface plays an important role in the heterogeneous ice nucleation mechanism. References: L. Lupi, A. Hudait and V. Molinero, J. Am. Chem. Soc

  17. The control of transmembrane helix transverse position in membranes by hydrophilic residues.

    Science.gov (United States)

    Krishnakumar, Shyam S; London, Erwin

    2007-12-14

    The ability of hydrophilic residues to shift the transverse position of transmembrane (TM) helices within bilayers was studied in model membrane vesicles. Transverse shifts were detected by fluorescence measurements of the membrane depth of a Trp residue at the center of a hydrophobic sequence. They were also estimated from the effective length of the TM-spanning sequence, derived from the stability of the TM configuration under conditions of negative hydrophobic mismatch. Hydrophilic residues (at the fifth position in a 21-residue hydrophobic sequence composed of alternating Leu and Ala residues and flanked on both ends by two Lys) induced transverse shifts that moved the hydrophilic residue closer to the membrane surface. At pH 7, the dependence of the extent of shift upon the identity of the hydrophilic residue increased in the order: L snorkeling). Additional experiments showed that shift was also modulated by the position of the hydrophilic residue in the sequence and the hydrophobicity of the sequence moved out of the bilayer core upon shifting. Combined, these studies show that the insertion boundaries of TM helices are very sensitive to sequence, and can be altered even by weakly hydrophilic residues. Thus, many TM helices may have the capacity to exist in more than one transverse position. Knowledge of the magnitudes of transverse shifts induced by different hydrophilic residues should be useful for design of mutagenesis studies measuring the effect of transverse TM helix position upon function.

  18. Composite hydrophilic coating for conditioner aluminum fins

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    To solve the so-called "white rust" and 'water bridge" problems of the aluminum fins for heat exchanger of automobile air conditioner, aimed at nationalizing the art of hydrophilic coating technology, the choice of coating forming and curing materials was investigated. By measuring the water contact angle, SEM surface scanning and ingredients analysis of the coating, optimal parameters and composition are acquired. The coating forming mechanisms of the composition was also expatiated. The coating obtained has good hydrophilic and other properties.

  19. Hydrophilic Carotenoids: Recent Progress

    Directory of Open Access Journals (Sweden)

    Attila Agócs

    2012-04-01

    Full Text Available Carotenoids are substantially hydrophobic antioxidants. Hydrophobicity is this context is rather a disadvantage, because their utilization in medicine as antioxidants or in food chemistry as colorants would require some water dispersibility for their effective uptake or use in many other ways. In the past 15 years several attempts were made to synthetize partially hydrophilic carotenoids. This review compiles the recently synthetized hydrophilic carotenoid derivatives.

  20. Effects of surface functionalization of hydrophilic NaYF4 nanocrystals doped with Eu3+ on glutamate and GABA transport in brain synaptosomes

    Science.gov (United States)

    Sojka, Bartlomiej; Kociołek, Daria; Banski, Mateusz; Borisova, Tatiana; Pozdnyakova, Natalia; Pastukhov, Artem; Borysov, Arsenii; Dudarenko, Marina; Podhorodecki, Artur

    2017-08-01

    Specific rare earth doped nanocrystals (NCs), a recent class of nanoparticles with fluorescent features, have great bioanalytical potential. Neuroactive properties of NaYF4 nanocrystals doped with Eu3+ were assessed based on the analysis of their effects on glutamate- and γ-aminobutyric acid (GABA) transport process in nerve terminals isolated from rat brain (synaptosomes). Two types of hydrophilic NCs were examined in this work: (i) coated by polyethylene glycol (PEG) and (ii) with OH groups at the surface. It was found that NaYF4:Eu3+-PEG and NaYF4:Eu3+-OH within the concentration range of 0.5-3.5 and 0.5-1.5 mg/ml, respectively, did not influence Na+-dependent transporter-dependent l-[14C]glutamate and [3H]GABA uptake and the ambient level of the neurotransmitters in the synaptosomes. An increase in NaYF4:Eu3+-PEG and NaYF4:Eu3+-OH concentrations up to 7.5 and 3.5 mg/ml, respectively, led to the (1) attenuation of the initial velocity of uptake of l-[14C]glutamate and [3H]GABA and (2) elevation of ambient neurotransmitters in the suspension of nerve terminals. In the mentioned concentrations, nanocrystals did not influence acidification of synaptic vesicles that was shown with pH-sensitive fluorescent dye acridine orange, however, decreased the potential of the plasma membrane of synaptosomes. In comparison with other nanoparticles studied with similar methodological approach, NCs start to exhibit their effects on neurotransmitter transport at concentrations several times higher than those shown for carbon dots, detonation nanodiamonds and an iron storage protein ferritin, whose activity can be registered at 0.08, 0.5 and 0.08 mg/ml, respectively. Therefore, NCs can be considered lesser neurotoxic as compared to above nanoparticles.

  1. Modification and Applications of Hydrophilic Polypropylene Membrane

    Science.gov (United States)

    Ariono, Danu; Kusuma Wardani, Anita

    2017-07-01

    Polypropylene (PP) is one of the most important polymers for microporous membrane due to its high void volume, well-controlled porosity, high thermal and chemical stability, and low cost. However, the hydrophobicity of PP becomes a limitation to broaden its applications. Furthermore, membrane fouling occurs more seriously on hydrophobic membranes than hydrophilic ones. To solve this problem, surface modifications have been developed to enhance PP membrane hydrophilicity without changing its bulk properties. Graft polymerization and plasma treatment are the most popular techniques for surface hydrophilization. Some studies showed that highly hydrophilic PP membranes with water contact angle less than 20° could be obtained by plasma treatment and graft polymerization. Furthermore, during plasma treatment, polar groups were formed on the PP membrane surface thus increased water uptake. To bring brief explanation on various research trends for PP modification, this paper provides a review of surface hydrophilization of microporous PP membrane, including plasma treatment and graft polymerization. The effects of surface modification on PP membrane performance such as porosity, water contact angle, and water flux are also discussed. In addition, the applications of modified PP membrane are presented as well.

  2. Modelling land surface - atmosphere interactions

    DEFF Research Database (Denmark)

    Rasmussen, Søren Højmark

    related to inaccurate land surface modelling, e.g. enhanced warm bias in warm dry summer months. Coupling the regional climate model to a hydrological model shows the potential of improving the surface flux simulations in dry periods and the 2 m air temperature in general. In the dry periods......The study is investigates modelling of land surface – atmosphere interactions in context of fully coupled climatehydrological model. With a special focus of under what condition a fully coupled model system is needed. Regional climate model inter-comparison projects as ENSEMBLES have shown bias...... representation of groundwater in the hydrological model is found to important and this imply resolving the small river valleys. Because, the important shallow groundwater is found in the river valleys. If the model does not represent the shallow groundwater then the area mean surface flux calculation...

  3. Hierarchical micro-nano structured Ti6Al4V surface topography via two-step etching process for enhanced hydrophilicity and osteoblastic responses.

    Science.gov (United States)

    Moon, Byeong-Seok; Kim, Sungwon; Kim, Hyoun-Ee; Jang, Tae-Sik

    2017-04-01

    Hierarchical micro-nano (HMN) surface structuring of dental implants is a fascinating strategy for achieving fast and mechanically stable fixation due to the synergetic effect of micro- and nano-scale surface roughness with surrounding tissues. However, the introduction of a well-defined nanostructure on a microstructure having complex surface geometry is still challenging. As a means of fabricating HMN surface on Ti6Al4V-ELI, target-ion induced plasma sputtering (TIPS) was used onto a sand-blasted, large-grit and acid-etched substrate. The HMN surface topography was simply controlled by adjusting the tantalum (Ta) target power of the TIPS technique, which is directly related to the Ta ion flux and the surface chemical composition of the substrate. Characterization using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and laser scanning microscopy (LSM) verified that well-defined nano-patterned surface structures with a depth of ~300 to 400nm and a width of ~60 to 70nm were uniformly distributed and followed the complex micron-sized surface geometry. In vitro cellular responses of pre-osteoblast cells (MC3T3-E1) were assessed by attachment and proliferation of cells on flat, nano-roughened, micro-roughened, and an HMN surface structure of Ti6Al4V-ELI. Moreover, an in vivo dog mandible defect model study was used to investigate the biological effect of the HMN surface structure compared with the micro-roughened surface. The results showed that the surface nanostructure significantly increased the cellular activities of flat and micro-roughened Ti, and the bone-to-implant contact area and new bone volume were significantly improved on the HMN surface structured Ti. These results support the idea that an HMN surface structure on Ti6Al4V-ELI alloy has great potential for enhancing the biological performance of dental implants.

  4. Syntheses and self-assembly of novel asparagine-derived amphiphiles: Applications in the encapsulation of proteins, hydrophobic, and hydrophilic drug models

    Science.gov (United States)

    Mfuh, Adelphe Mbufung

    This thesis focuses mainly on the synthesis, characterization, and self-assembly of a novel series of asparagine-derived amphiphiles and their use in the preparation and stabilization of nano and microcapsules for the encapsulation of proteins, and hydrophilic and hydrophobic drug models. Chapter 1 gives a brief literature overview of lipid molecular assembly, which covers some aspects of morphological analyses, encapsulation of chemical entity and some reported characterization techniques of supramolecular assemblies. It introduces the scope of this dissertation and contains some information on stimulus responsive liposomal systems for controlled release of drug models. Chapter 2 introduces a novel asparagine-derived lipid bearing two fatty chains (C11 and C17) and a tetrahydropyrimidinone head group. It presents information on the synthesis and characterization of this lipid and describes the self-assembly and effects of this lipid in distearoyl phosphatidyl choline bilayer. Chapter 3 presents the synthesis and characterization of a series of ALAn,m (where n and m represent the length of the hydrocarbon chains on the asparagine-derived, heterocyclic head group). It contains data on the effect of chain length, solvent media and head group ionization on the conformational equilibrium about a tertiary amide bond in ALAn,m. The chapter also examines the influence of chain length on ALAn,m on the colloidal stability of DSPC liposomes. Chapter 4 presents the first example of an N,N-acetal linkage in a novel pH responsive nanocarrier system obtained from the cyclocondensation of dodecanal with sodium asparaginate. Data is presented on the spontaneous self-assembly, encapsulation studies and morphological characterization of the nano-systems with the inclusion of cholesterol as additive. Chapter 5 presents the development of a photoresponsive nanocarrier via the self- assembly of an asparagine-derived lipid containing a coumarin unit in the hydrophobic domain. The

  5. CHARACTERISTICS OF MEMBRANE SURFACE HYDROPHILICITY DURING ULTRAFILTRATION PROCESS OPERATION%超滤运行过程中膜表面亲水性的变化特征

    Institute of Scientific and Technical Information of China (English)

    乔铁军; Doris W T AU; 张锡辉

    2013-01-01

    This paper aims to investigate the variance of membrane hydrophilicity during ultrafiltration (UF) operation.Membrane surface contact angle was studied on various operation conditions in a bench-scale experiment apparatus.The results showed that membrane contact angle decreased during the long term operation.Water backwashing and chemical cleaning both have a little influence on membrane contact angle.Membrane contact angle increased first and then decreased during the filtration period,and decreased with increasing the flux.Compare with sedimentation,granular activated carbon filtration effluent more easily caused the decline of contact angle.Membrane contact angle increased with increasing the pH values.Chemical cleaning led to the increase of contact angle.Contact angle changed a little when cleaned by NaOH,but increased obviously when cleaned by HCl and NaClO.In conclusion,membrane hydrophilicty varied during the UF operation,which was impacted by raw water characteristic,operation parameters and backwashing methods.%为了研究膜亲水性在超滤运行过程中的变化规律,采用小试装置,研究了在不同运行状况下的膜接触角变化.结果表明,在长期的运行过程中,膜接触角均不同程度地下降.单独水反冲洗和化学加强反洗对接触角的影响较小.膜接触角在过滤周期内先升高再降低.随着通量的增加,膜接触角逐渐降低.与沉后水相比,活性炭过滤出水更易引起膜接触角下降.随着pH升高,膜接触角会上升.化学清洗使膜接触角增加,当用NaOH清洗时,接触角变化不大;而用HC1和NaC1O清洗时,接触角明显增加.总之,膜表面亲水性在运行过程中会发生一定变化,并且受到原水水质、操作参数和反冲洗方式等方面影响.

  6. Findings of an experimental study in a rabbit model on posterior capsule opacification after implantation of hydrophobic acrylic and hydrophilic acrylic intraocular lenses

    Directory of Open Access Journals (Sweden)

    Nikolaos Trakos

    2009-01-01

    Full Text Available Nikolaos Trakos1, Elli Ioachim2, Elena Tsanou2, Miltiadis Aspiotis1, Konstantinos Psilas1, Chris Kalogeropoulos11University Eye Clinic of Ioannina, Ioannina, Greece; 2Pathology Department, University of Ioannina, Ioannina, GreecePurpose: Study on cell growth on the posterior capsule after implantation of hydrophobic acrylic (Acrysof SA 60 AT and hydrophilic acrylic (Akreos Disc intraocular lenses (IOL in a rabbit model and comparison of posterior capsule opacification (PCO.Methods: Phacoemulsification was performed in 22 rabbit eyes, and two different IOL types (Acrysof SA60 AT and Akreos Disc were implanted. These IOLs had the same optic geometry (square edged but different material and design. Central PCO (CPCO, peripheral PCO (PPCO, Sommering’s ring (SR formation, type of growth, extension of PCO, cell type, inhibition, and fibrosis were evaluated three weeks after surgery. Histological sections of each globe were prepared to document the evaluation of PCO.Results: No statistically significant difference was observed between a hydrophobic acrylic IOL and a hydrophilic acrylic IOL in relation to the CPCO, PPCO, type of growth, extension, cell type, inhibition, and fibrosis. Statistically significant difference was observed in relation to the formation of SR with Acrysof SA 60 AT group presenting more SR than Akreos Disc group.Conclusion: PCO was not influenced by the material of the IOL or the design of the haptics of the IOLs we studied.Keywords: posterior capsule opacification, intraocular lenses, rabbit model

  7. Heterogeneous nano-Fe/Ca/CaO catalytic ozonation for selective surface hydrophilization of plastics containing brominated and chlorinated flame retardants (B/CFRs): separation from automobile shredder residue by froth flotation.

    Science.gov (United States)

    Mallampati, Srinivasa Reddy; Lee, Byoung Ho; Mitoma, Yoshiharu; Simion, Cristian

    2016-12-09

    One method of weakening the inherently hydrophobic surface of plastics relevant to flotation separation is heterogeneous nano-Fe/Ca/CaO catalytic ozonation. Nano-Fe/Ca/CaO-catalyzed ozonation for 15 min efficiently decreases the surface hydrophobicity of brominated and chlorinated flame retardant (B/CFR)-containing plastics (such as acrylonitrile-butadienestyrene (ABS), high-impact polystyrene (HIPS), and polyvinyl chloride (PVC)) in automobile shredder residue (ASR) to such an extent that their flotation ability is entirely depressed. Such a hydrophilization treatment also stimulates the ABS, HIPS, and PVC surface roughness, wetting of the surface, and the thermodynamic equilibrium conditions at the surface and ultimately changes surface polarity. SEM-EDS, AFM, and XPS analyses of the PVC and ABS surfaces demonstrated a marked decrease in [Cl/Br] and a significant increase in the number of hydrophilic groups, such as C-O, C=O, and (C=O)-O. Under froth flotation conditions at 50 rpm, about 99.5 % of ABS and 99.5 % of HIPS in ASR samples settled out, resulting in a purity of 98 and 98.5 % for ABS and HIPS in ASR samples, respectively. Furthermore, at 150 rpm, we also obtained 100 % PVC separation in the settled fraction, with 98 % purity in ASR. Total recovery of non-B/CFR-containing plastics reached nearly 100 % in the floating fraction. The amount of nano-Fe/Ca/CaO reagent employed during ozonation is very small, and additional removal of surface contaminants from the recycled ASR plastic surfaces by ozonation makes the developed process simpler, greener, and more effective.

  8. Molecular-Level Insight of the Effect of Hofmeister Anions on the Interfacial Surface Tension of a Model Protein

    Energy Technology Data Exchange (ETDEWEB)

    Willow, Soohaeng Yoo; Xantheas, Sotiris S.

    2017-03-21

    The effect of the Hofmeister anion series on the structure and stability of proteins is often discussed using simple systems such as a water-vapor interface with the assumption that the vapor region mimics the hydrophobic surface. Microscopic theories suggest that the Hofmeister anion series is highly correlated with the different contributions of the various ions to the surface tension of such a water-vapor interface. Proteins, however, have both hydrophobic and hydrophilic regions rather than just a pure hydrophobic one. Using a solvated parallel β -sheet layer consisting of both hydrophobic and positively charged hydrophilic surfaces as a more realistic model to represent a protein surface, we investigated the interaction of such a system with hydrophilic-like (SO42-) and hydrophobic-like (ClO4-) anions via Born-Oppenheimer Molecular Dynamics (BOMD) simulations. We found that both the SO42- and ClO4- anions prefer to reside on the hydrophilic rather than on the hydrophobic surface of the parallel β -sheet layer. In addition, our simulations suggest that the ClO4- ions not only penetrate towards the peptide groups through the hydrophilic residues, but also allow water molecules to penetrate as well to form water-peptide hydrogen bonds, while the SO42- ions stabilize the interface of the water-hydrophilic surface. Our results render a plausible explanation of why hydrophobic-like Hofmeister anions act as protein denaturants. This work was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences and Biosciences. Pacific Northwest National Laboratory (PNNL) is a multiprogram national laboratory operated for DOE by Battelle.

  9. Hydrophilic nanoporous materials

    DEFF Research Database (Denmark)

    2010-01-01

    The present application discloses a method for preparing and rendering hydrophilic a nanoporous material of a polymer matrix which has a porosity of 0.1-90 percent (v/v), such that the ratio between the final water absorption (percent (w/w)) and the porosity (percent (v/v)) is at least 0.05, the ......The present application discloses a method for preparing and rendering hydrophilic a nanoporous material of a polymer matrix which has a porosity of 0.1-90 percent (v/v), such that the ratio between the final water absorption (percent (w/w)) and the porosity (percent (v/v)) is at least 0.......05, the method comprising the steps of: (a) preparing a precursor material comprising at least one polymeric component and having a first phase and a second phase; (b) removal of at least a part of the first phase of the precursor material prepared in step (a) so as to leave behind a nanoporous material...... of the polymer matrix; (c) irradiating at least a part of said nanoporous material with light of a wave length of in the range of 250-400 nm (or 200-700 nm) in the presence of oxygen and/or ozone. Corresponding hydrophilic nanoporous materials are also disclosed. L...

  10. Pavement Aging Model by Response Surface Modeling

    Directory of Open Access Journals (Sweden)

    Manzano-Ramírez A.

    2011-10-01

    Full Text Available In this work, surface course aging was modeled by Response Surface Methodology (RSM. The Marshall specimens were placed in a conventional oven for time and temperature conditions established on the basis of the environment factors of the region where the surface course is constructed by AC-20 from the Ing. Antonio M. Amor refinery. Volatilized material (VM, load resistance increment (ΔL and flow resistance increment (ΔF models were developed by the RSM. Cylindrical specimens with real aging were extracted from the surface course pilot to evaluate the error of the models. The VM model was adequate, in contrast (ΔL and (ΔF models were almost adequate with an error of 20 %, that was associated with the other environmental factors, which were not considered at the beginning of the research.

  11. Effects of hydrophilic solvent and oxidation resistance post surface treatment on molecular structure and forward osmosis performance of polyamide thin-film composite (TFC) membranes

    Science.gov (United States)

    Jia, Qibo; Xu, Yangyu; Shen, Jianquan; Yang, Haijun; Zhou, Lu

    2015-11-01

    In this article, novel hydrophilic solvents and antioxidants were used to post-treat aromatic polyamide thin-film composite (TFC) hollow fiber forward osmosis (FO) membranes. The effects of trimesoyl chloride (TMC) and oxalic acid on the structure of polyamide skin layer were investigated using ATR-FTIR and XPS analyses. Pure water flux and rejection of salts were detected using 2 M NaCl solution as draw solutions in FO processes. The results demonstrated that hydrophilic solvent N-methyl pyrrolidone (NMP) enhanced the water flux and kept a high salt retention of the TFC FO membrane. TMC and oxalic acid were both found to improve the oxidation resistance properties of the skin layer of TFC membrane because the electron-withdrawing carboxyl groups reduced the activity of polyamide molecular. The effects of the oxalic acid and carbodiimide on the molecular structures and the FO water flux of the polyamide TFC membranes were more marked than those of TMC. The novel TFC FO membrane treated by oxalic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) exhibited a high level of water flux (20.33 L m-2 h-1), and the rates of salt rejection and salt reverse rejection were higher by 50% and 83%, respectively.

  12. Condensing Heat Exchanger with Hydrophilic Antimicrobial Coating

    Science.gov (United States)

    Thomas, Christopher M. (Inventor); Ma, Yonghui (Inventor)

    2014-01-01

    A multi-layer antimicrobial hydrophilic coating is applied to a substrate of anodized aluminum, although other materials may form the substrate. A silver layer is sputtered onto a thoroughly clean anodized surface of the aluminum to about 400 nm thickness. A layer of crosslinked, silicon-based macromolecular structure about 10 nm thickness overlies the silver layer, and the outermost surface of the layer of crosslinked, silicon-based macromolecular structure is hydroxide terminated to produce a hydrophilic surface with a water drop contact angle of less than 10.degree.. The coated substrate may be one of multiple fins in a condensing heat exchanger for use in the microgravity of space, which has narrow channels defined between angled fins such that the surface tension of condensed water moves water by capillary flow to a central location where it is pumped to storage. The antimicrobial coating prevents obstruction of the capillary passages.

  13. Photocatalytic, highly hydrophilic porcelain stoneware slabs

    Science.gov (United States)

    Raimondo, M.; Guarini, G.; Zanelli, C.; Marani, F.; Fossa, L.; Dondi, M.

    2011-10-01

    Photocatalytic, highly hydrophilic industrial porcelain stoneware large slabs were realized by deposition of nanostructured TiO2 coatings. Different surface finishing and experimental conditions were considered in order to assess the industrial feasibility. Photocatalytic and wetting behaviour of functionalized slabs mainly depends on surface phase composition in terms of anatase/rutile ratio, this involving - as a key issue - the deposition of TiO2 on industrially sintered products with an additional annealing step to strengthen coatings' performances and durability.

  14. Effects of hydrophilic solvent and oxidation resistance post surface treatment on molecular structure and forward osmosis performance of polyamide thin-film composite (TFC) membranes

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Qibo; Xu, Yangyu [School of Environment, Tsinghua University, Beijing 100084 (China); Shen, Jianquan [Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Yang, Haijun, E-mail: yanghj@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Zhou, Lu, E-mail: zhoulu@tsinghua.edu.cn [School of Environment, Tsinghua University, Beijing 100084 (China)

    2015-11-30

    Graphical abstract: - Highlights: • NMP promotes swelling of polyamide, which enhances the TFC FO membrane water flux. • Electron-withdrawing carboxyl groups reduce the activity of polyamide molecules. • TMC and oxalic acid can improve the oxidation resistance properties of the FO membrane. • Oxalic acid and EDC improve the FO membrane separation performance significantly. - Abstract: In this article, novel hydrophilic solvents and antioxidants were used to post-treat aromatic polyamide thin-film composite (TFC) hollow fiber forward osmosis (FO) membranes. The effects of trimesoyl chloride (TMC) and oxalic acid on the structure of polyamide skin layer were investigated using ATR-FTIR and XPS analyses. Pure water flux and rejection of salts were detected using 2 M NaCl solution as draw solutions in FO processes. The results demonstrated that hydrophilic solvent N-methyl pyrrolidone (NMP) enhanced the water flux and kept a high salt retention of the TFC FO membrane. TMC and oxalic acid were both found to improve the oxidation resistance properties of the skin layer of TFC membrane because the electron-withdrawing carboxyl groups reduced the activity of polyamide molecular. The effects of the oxalic acid and carbodiimide on the molecular structures and the FO water flux of the polyamide TFC membranes were more marked than those of TMC. The novel TFC FO membrane treated by oxalic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) exhibited a high level of water flux (20.33 L m{sup −2} h{sup −1}), and the rates of salt rejection and salt reverse rejection were higher by 50% and 83%, respectively.

  15. Treatment of ASP produced water with hydrophilic fibre ball filtration

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The conventional treatment process cannot meet the need for treatment of produced water from alkaline/surfactant/polymer flooding( ASP produced water) in Daqing oilfield. In this study, a new type of hydrophilic fibre ball medium was developed through surface modification method. The hydrophilic property of the surface modified fibre ball was tested with ASP produced liquid at laboratory. The results showed that this fibre ball had higher oil degreasing efficiency. The surface components were also observed by Scanning Electron Microscope and X-ray Photoelectron Spectroscopy, the result showed that the hydrophilic fibre' s surface was covered by sulfonic group. Using hydrophilic fibre ball as filter medium, a new type of filter was designed to treat ASP produced water in pilot-scale experiments. The obtained results indicated that this type of filter had high capability and efficiency for the treatment of ASP produced water. This filter should have a better application prospect in oilfield produced water treatment.

  16. Conformational mechanics, adsorption, and normal force interactions of lubricin and hyaluronic acid on model surfaces.

    Science.gov (United States)

    Chang, Debby P; Abu-Lail, Nehal I; Guilak, Farshid; Jay, Gregory D; Zauscher, Stefan

    2008-02-19

    Glycoproteins, such as lubricin, and hyaluronic acid (HA) play a prominent role in the boundary lubrication mechanism in diarthrodial joints. Although many studies have tried to elucidate the lubrication mechanisms of articular cartilage, the molecular details of how lubricin and HA interact with cartilage surfaces and mediate their interaction still remain poorly understood. Here we used model substrates, functionalized with self-assembled monolayers terminating in hydroxyl or methyl groups, (1) to determine the effect of surface chemistry on lubricin and HA adsorption using surface plasmon resonance (SPR) and (2) to study normal force interactions between these surfaces as a function of lubricin and HA concentration using colloidal probe microscopy. We found that lubricin is amphiphilic and adsorbed strongly onto both methyl- and hydroxyl-terminated surfaces. On hydrophobic surfaces, lubricin likely adopts a compact, looplike conformation in which its hydrophobic domains at the N and C termini serve as surface anchors. On hydrophilic surfaces, lubricin likely adsorbs anywhere along its hydrophilic central domain and adopts, with increasing solution concentration, an extended tail-like conformation. Overall, lubricin develops strong repulsive interactions when compressing two surfaces into contact. Furthermore, upon surface separation, adhesion occurs between the surfaces as a result of molecular bridging and chain disentanglement. This behavior is in contrast to that of HA, which does not adsorb appreciably on either of the model surfaces and does not develop significant repulsive interactions. Adhesive forces, particularly between the hydrophobic surfaces, are large and not appreciably affected by HA. For a mixture of lubricin and HA, we observed slightly larger adsorptions and repulsions than those found for lubricin alone. Our experiments suggest that this interaction depends on unspecific physical rather than chemical interactions between lubricin and HA. We

  17. Antimicrobial and anti-thrombogenic features combined in hydrophilic surface coatings for skin-penetrating catheters. Synergy of co-embedded silver particles and heparin.

    Science.gov (United States)

    Croes, Sander; Stobberingh, Ellen E; Stevens, Kris N J; Knetsch, Menno L W; Koole, Leo H

    2011-07-01

    Percutaneous (skin-penetrating) catheters such as central venous catheters (CVCs), are used ubiquitously in the treatment of critically ill patients, although it is known that the risks for serious complications, particularly bloodstream infection and thromboembolism, are high. Materials science and engineering offer important new perspectives regarding further improvement of CVCs. A promising approach is the use of synthetic biocompatible hydrogel coatings with both silver particles and heparin embedded therein. Such formulations combine the well-known broad-spectrum antimicrobial features of silver with the anticoagulant activity of immobilized heparin. Previous work revealed that heparin augments antimicrobial activity of silver, while maintaining its anticoagulant function. This study set out to investigate the synergy of heparin and silver in more detail. Exit-challenge tests, experiments on bacterial killing and adherence, as well as in vitro challenge tests with three Staphylococcus aureus strains (one reference strain, and two clinical isolates) consistently showed the synergistic effect. In addition, the impact of changing the coating's hydrophilicity, and changing the silver concentration in the coatings, were examined. The experimental results, taken together and combined with data from the literature, point out that synergy of heparin and silver is best explained by binding of Ag(+) ions to heparin within the swollen coating, followed by release of heparin-Ag(+) complexes upon immersion of the coatings in an aqueous environment such as blood. Possible implications of this work regarding the development of improved/safer CVCs are briefly discussed.

  18. Laser surface texturing of 316L stainless steel in air and water: A method for increasing hydrophilicity via direct creation of microstructures

    Science.gov (United States)

    Razi, Sepehr; Madanipour, Khosro; Mollabashi, Mahmoud

    2016-06-01

    Laser processing of materials in water contact is sometimes employed for improving the machining, cutting or welding quality. Here, we demonstrate surface patterning of stainless steel grade 316L by nano-second laser processing in air and water. Suitable adjustments of laser parameters offer a variety of surface patterns on the treated targets. Furthermore alterations of different surface features such as surface chemistry and wettability are investigated in various processing circumstances. More than surface morphology, remarkable differences are observed in the surface oxygen content and wettability of the samples treated in air and water at the same laser processing conditions. Mechanisms of the changes are discussed extensively.

  19. Physical and numerical modelling of biomimetic approaches of natural hydrophobic surfaces

    Institute of Scientific and Technical Information of China (English)

    YAN YuYing

    2009-01-01

    Physical and numerical models of the hydrophobic and self-cleaning characteristics of an object sur-face are developed, and a micro/meso scope numerical approach and simulation based on the lattice Boltzmann method (LBM) is achieved. The modelling focuses on surface tension dominated behaviour of water droplets in air spreading on hydrophilic surface with hydrophobic strips of different sizes and contact angles under different physical and interracial conditions. Applying the LBM model, the drop-lets behaviours on heterogeneous partial wetting surfaces are studied and simulated. In the simula-tions, the interactions between the fluid-fluid interface and the partial wetting wall are typically con-sidered; the phenomena of droplets spreading and breaking up, as well as the effect of hydrophobic strips on the surface wettability or self-cleaning characteristics are simulated and studied.

  20. Coarse Grained Modeling of The Interface BetweenWater and Heterogeneous Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Willard, Adam; Chandler, David

    2008-06-23

    Using coarse grained models we investigate the behavior of water adjacent to an extended hydrophobic surface peppered with various fractions of hydrophilic patches of different sizes. We study the spatial dependence of the mean interface height, the solvent density fluctuations related to drying the patchy substrate, and the spatial dependence of interfacial fluctuations. We find that adding small uniform attractive interactions between the substrate and solvent cause the mean position of the interface to be very close to the substrate. Nevertheless, the interfacial fluctuations are large and spatially heterogeneous in response to the underlying patchy substrate. We discuss the implications of these findings to the assembly of heterogeneous surfaces.

  1. A Comparative Evaluation of Dimensional Accuracy and Surface Detail Reproduction of Four Hydrophilic Vinyl Polysiloxane Impression Materials Tested Under Dry, Moist, and Wet Conditions-An In Vitro Study.

    Science.gov (United States)

    Nagrath, Rahul; Lahori, Manesh; Agrawal, Manjari

    2014-12-01

    Vinyl polysiloxane (VPS) impression materials have application in a wide variety of situations in both fixed and removable prosthodontics. A major limitation of VPS impression materials is their hydrophobicity. There are two aspects of this problem, the wettability of the polymerized impression by dental gypsum materials and the ability of the unpolymerized material to wet intraoral tissues. To address this problem, manufacturers have added surfactants and labelled these new products as "hydrophilic vinyl polysiloxane." The purpose of this study was to evaluate and compare dimensional accuracy and surface detail reproduction of four hydrophilic VPS impression materials, when used under dry, moist, and wet conditions. A total of 180 samples were made of stainless steel die similar to as described in ADA sp. no. 19. The die was scored with three horizontal and two vertical lines. Impressions were made under dry, moist and wet conditions. Dimensional accuracy was measured by comparing the length of the middle horizontal line in each impression to the same line on the metal die, by using Universal Length Measuring machine. A 2-way ANOVA was performed on the percentage change data for measured lengths of the 4 impression materials under the 3 conditions to evaluate dimensional accuracy. Surface detail was evaluated in two ways: (1) by use of criteria similar to ADA sp. no. 19 for detail reproduction, and (2) by use of a method that categorized the impressions as satisfactory or unsatisfactory based on their surface characteristics: presence of pits, voids, or roughness. Pearson X2 (α = 0.05) was used to compare surface detail reproduction results. Conditions (dry, moist, and wet) did not cause significant adverse effects on the dimensional accuracy of all the four material. With both surface detail analyses, dry, moist, and wet conditions had a significant effect on the detail reproduction of all the four materials (P study concluded that the dimensional accuracy of

  2. Axelrod's Model with Surface Tension

    CERN Document Server

    Pace, Bruno

    2012-01-01

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

  3. Improvement in surface hydrophilicity and resistance to deformation of natural leather through O2/H2O low-temperature plasma treatment

    Science.gov (United States)

    You, Xuewei; Gou, Li; Tong, Xingye

    2016-01-01

    The natural leather was modified through O2/H2O low-temperature plasma treatment. Surface morphology was characterized by scanning electron microscopy (SEM) and the results showed that the pores on the leather surface became deeper and larger with enhanced permeability of water and vapor. XPS and FTIR-ATR was performed to determine the chemical composition of natural leather surface. Oxygen-containing groups were successfully grafted onto the surface of natural leather and oxygen content increased with longer treatment time. After O2/H2O plasma treatment, initial water contact angle was about 21° and water contact angles were not beyond 55° after being stored for 3 days. Furthermore, the tensile test indicated that the resistance to deformation had a prominent transform without sacrificing the tensile strength.

  4. Surface modification of poly(vinylidene fluoride) membrane with hydrophilic and anti-fouling performance via a two-step polymerization

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Gui-E; Sun, Li; Huang, Hui-Hong; Liu, Yan-Jun [Shanghai Institute of Technology, Shanghai (China); Xu, Zhen-Liang; Yang, Hu [East China University of Science and Technology, Shanghai (China)

    2015-12-15

    The surface modification of poly (vinylidene fluoride) (PVDF) membrane was performed via a two-step polymerization reactions. Poly (acrylic acid) (PAAc) was first grafted onto the membrane surface for the preparation of PVDF-g-PAAc membrane, and then poly (ethylene glycol) 200 (PEG 200) was immobilized on the membrane surface by the esterification reaction for the fabrication of PVDF-g-PEGA membrane. Attenuated total reflectance (ATR) FTIR, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), and protein adsorption, water flux, water content and dynamic contact angle were conducted to characterize the structures and performance of the resultant PVDF membranes. The experimental results showed that the adsorption of bovine serum albumin (BSA) on the PVDF-g-PEGA membrane decreased about 80% when the grafting ratio reached to 15 wt%, compared with the pristine PVDF membrane. Moreover, the water contact angle of the membrane dropped to 60.5o, while the membrane pore sizes remained little changed.

  5. Unusual ultra-hydrophilic, porous carbon cuboids for atmospheric-water capture.

    Science.gov (United States)

    Hao, Guang-Ping; Mondin, Giovanni; Zheng, Zhikun; Biemelt, Tim; Klosz, Stefan; Schubel, René; Eychmüller, Alexander; Kaskel, Stefan

    2015-02-02

    There is significant interest in high-performance materials that can directly and efficiently capture water vapor, particularly from air. Herein, we report a class of novel porous carbon cuboids with unusual ultra-hydrophilic properties, over which the synergistic effects between surface heterogeneity and micropore architecture is maximized, leading to the best atmospheric water-capture performance among porous carbons to date, with a water capacity of up to 9.82 mmol g(-1) at P/P0 =0.2 and 25 °C (20% relative humidity or 6000 ppm). Benefiting from properties, such as defined morphology, narrow pore size distribution, and high heterogeneity, this series of functional carbons may serve as model materials for fundamental research on carbon chemistry and the advance of new types of materials for water-vapor capture as well as other applications requiring combined highly hydrophilic surface chemistry, developed hierarchical porosity, and excellent stability.

  6. Phobos surface spectra mineralogical modeling

    Science.gov (United States)

    Pajola, M.; Lazzarin, M.; Dalle Ore, C. M.; Cruikshank, D. P.; Roush, T. L.; Pendleton, Y.; Bertini, I.; Magrin, S.; Carli, C.; La Forgia, F.; Barbieri, C.

    2014-04-01

    A mineralogical model composed of a mixture of Tagish Lake meteorite (TL) and Pyroxene Glass (PM80) was presented in [1] to explain the surface reflectance of Phobos from 0.25 to 4.0 μm. The positive results we obtained, when comparing the OSIRIS data [2] extended in wavelength to include the [3,4] spectra, forced us to perform a wider comparison between our TL-PM80 model and the CRISM and OMEGA Phobos spectra presented in [5]. Such spectra cover three different regions of interest (ROIs) situated in the Phobos sub-Mars hemisphere: the interior of the Stickney crater, its eastern rim, and its proximity terrain southeast of the Reldresal crater. We decided to vary the percentage mixture of the components of our model (80% TL, 20% PM80), between pure TL and pure PM80, by means of the radiative transfer code based on the [6] formulation of the slab approximation. Once this spectral range was derived, see Fig. 1, we attempted to compare it with the [5] spectra between 0.4 and 2.6 μm, i.e. below the thermal emitted radiation, to see if any spectral match was possible. We observed that CRISM scaled spectra above 1.10 μm fall within pure Tagish Lake composition and the [1] model. The CRISM data below 1.10 μm present more discrepancies with our models, in particular for the Stickney's rim spectrum. Nevertheless the TL and PM80 components seem to be good mineralogical candidates on Phobos. We performed the same analysis with the OMEGA data and, again, we found out that the Stickney's rim spectrum lies out of our model range, while the two remaining spectra still lie between pure TL and 80% TL - 20% PM80, but indicating that a different, more complicated mixture is expected in order to explain properly both the spectral trend and the possible absorption bands located above 2.0 μm. Within this analysis, we point out that a big fraction of TL material (modeled pure or present with a minimum percentage of 80% mixed together with 20% PM80) seems to explain Phobos spectral

  7. Exceptionally high protection of photocarcinogenesis by topical application of (--)-epigallocatechin-3-gallate in hydrophilic cream in SKH-1 hairless mouse model: relationship to inhibition of UVB-induced global DNA hypomethylation.

    Science.gov (United States)

    Mittal, Anshu; Piyathilake, Chandrika; Hara, Yukihiko; Katiyar, Santosh K

    2003-01-01

    (--)-Epigallocatechin-3-gallate (EGCG) has been shown to have potent antiphotocarcinogenic activity, but it was required to develop a cream-based formulation for topical application. For topical application, we tested hydrophilic cream as a vehicle for EGCG. Treatment with EGCG ( approximately 1 mg/cm(2) skin area) in hydrophilic cream resulted in exceptionally high protection against photocarcinogenesis when determined in terms of tumor incidence, tumor multiplicity, and tumor size in a SKH-1 hairless mouse model. EGCG also inhibited malignant transformation of ultraviolet B (UVB)-induced papillomas to carcinomas. In order to determine the mechanism of prevention of photocarcinogenesis, we determined the effect of EGCG on global DNA methylation pattern using monoclonal antibodies against 5-methyl cytosine and DNA methyltransferase in the long-term UV-irradiated skin because altered DNA methylation silencing is recognized as a molecular hallmark of human cancer. We found that treatment with EGCG resulted in significant inhibition of UVB-induced global DNA hypomethylation pattern. Long-term application of EGCG did not show any apparent sign of toxicity in mice when determined in terms of skin appearance, lean mass, total bone mineral content, and total bone mineral density but showed reduction in fat mass when analyzed using dual-energy X-ray absorptiometry. These data suggest that hydrophilic cream could be a suitable vehicle for topical application of EGCG, and that EGCG is a promising candidate for future cancer therapies based on its influence on the epigenetic pathway.

  8. Exceptionally High Protection of Photocarcinogenesis by Topical Application of (--Epi gal locatechin-3-Gal late in Hydrophilic Cream in SKH-1 Hairless Mouse Model: Relationship to Inhibition of UVB-Induced Global DNA Hypomethylation

    Directory of Open Access Journals (Sweden)

    Anshu Mittal

    2003-11-01

    Full Text Available (--Epigallocatechin-3-gal late (EGCG has been shown to have potent antiphotocarcinogenic activity, but it was required to develop a cream-based formulation for topical application. For topical application, we tested hydrophilic cream as a vehicle for EGCG. Treatment with EGCG (≈ 1 mg/cm2 skin area in hydrophilic cream resulted in exceptionally high protection against photocarcinogenesis when determined in terms of tumor incidence, tumor multiplicity, and tumor size in a SKI-11-11 hairless mouse model. EGCG also inhibited malignant transformation of ultraviolet B (UVB-induced papillomas to carcinomas. In order to determine the mechanism of prevention of photocarcinogenesis, we determined the effect of EGCG on global DNA methylation pattern using monoclonal antibodies against 5-methyl cytosine and DNA methyltransferase in the long-term UV-irradiated skin because altered DNA methylation silencing is recognized as a molecular hallmark of human cancer. We found that treatment with EGCG resulted in significant inhibition of UVBinduced global DNA hypomethylation pattern. Longterm application of EGCG did not show any apparent sign of toxicity in mice when determined in terms of skin appearance, lean mass, total bone mineral content, and total bone mineral density but showed reduction in fat mass when analyzed using dual-energy X-ray absorptiometry. These data suggest that hydrophilic cream could be a suitable vehicle for topical application of EGCG, and that EGCG is a promising candidate for future cancer therapies based on its influence on the epigenetic pathway.

  9. Developing a general interaction potential for hydrophobic and hydrophilic interactions.

    Science.gov (United States)

    Donaldson, Stephen H; Røyne, Anja; Kristiansen, Kai; Rapp, Michael V; Das, Saurabh; Gebbie, Matthew A; Lee, Dong Woog; Stock, Philipp; Valtiner, Markus; Israelachvili, Jacob

    2015-02-24

    We review direct force measurements on a broad class of hydrophobic and hydrophilic surfaces. These measurements have enabled the development of a general interaction potential per unit area, W(D) = -2γ(i)Hy exp(-D/D(H)) in terms of a nondimensional Hydra parameter, Hy, that applies to both hydrophobic and hydrophilic interactions between extended surfaces. This potential allows one to quantitatively account for additional attractions and repulsions not included in the well-known combination of electrostatic double layer and van der Waals theories, the so-called Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. The interaction energy is exponentially decaying with decay length D(H) ≈ 0.3-2 nm for both hydrophobic and hydrophilic interactions, with the exact value of D(H) depending on the precise system and conditions. The pre-exponential factor depends on the interfacial tension, γ(i), of the interacting surfaces and Hy. For Hy > 0, the interaction potential describes interactions between partially hydrophobic surfaces, with the maximum hydrophobic interaction (i.e., two fully hydrophobic surfaces) corresponding to Hy = 1. Hydrophobic interactions between hydrophobic monolayer surfaces measured with the surface forces apparatus (SFA) are shown to be well described by the proposed interaction potential. The potential becomes repulsive for Hy < 0, corresponding to partially hydrophilic (hydrated) interfaces. Hydrated surfaces such as mica, silica, and lipid bilayers are discussed and reviewed in the context of the values of Hy appropriate for each system.

  10. Effective enhancement of hydrophilicity of solution indium zinc oxide-based thin-film transistors by oxygen plasma treatment of deposition layer surface

    Science.gov (United States)

    You, Hsin-Chiang; Wang, Yu-Chih

    2016-06-01

    In this paper, we describe the use of a simple and efficient sol-gel solution method for synthesizing indium zinc oxide (IZO) films for use as semiconductor channel layers in thin-film transistors (TFTs) on p-type silicon substrates. The performance of IZO-based TFTs was investigated, and the effect of oxygen plasma treatment on the surface of dielectric SiN x was observed. Oxygen plasma treatment effectively enhanced the electron mobility in IZO-based TFT devices from 0.005 to 1.56 cm2 V-1 s-1, an increase of more than 312 times, and effectively enhanced device performance. X-ray photoelectron spectroscopy analysis of the IZO film was performed to clarify element bonding.

  11. Self-Patterning of Silica/Epoxy Nanocomposite Underfill by Tailored Hydrophilic-Superhydrophobic Surfaces for 3D Integrated Circuit (IC) Stacking.

    Science.gov (United States)

    Tuan, Chia-Chi; James, Nathan Pataki; Lin, Ziyin; Chen, Yun; Liu, Yan; Moon, Kyoung-Sik; Li, Zhuo; Wong, C P

    2017-03-15

    As microelectronics are trending toward smaller packages and integrated circuit (IC) stacks nowadays, underfill, the polymer composite filled in between the IC chip and the substrate, becomes increasingly important for interconnection reliability. However, traditional underfills cannot meet the requirements for low-profile and fine pitch in high density IC stacking packages. Post-applied underfills have difficulties in flowing into the small gaps between the chip and the substrate, while pre-applied underfills face filler entrapment at bond pads. In this report, we present a self-patterning underfilling technology that uses selective wetting of underfill on Cu bond pads and Si3N4 passivation via surface energy engineering. This novel process, fully compatible with the conventional underfilling process, eliminates the issue of filler entrapment in typical pre-applied underfilling process, enabling high density and fine pitch IC die bonding.

  12. Surface modeling of soil antibiotics.

    Science.gov (United States)

    Shi, Wen-jiao; Yue, Tian-xiang; Du, Zheng-ping; Wang, Zong; Li, Xue-wen

    2016-02-01

    Large numbers of livestock and poultry feces are continuously applied into soils in intensive vegetable cultivation areas, and then some veterinary antibiotics are persistent existed in soils and cause health risk. For the spatial heterogeneity of antibiotic residues, developing a suitable technique to interpolate soil antibiotic residues is still a challenge. In this study, we developed an effective interpolator, high accuracy surface modeling (HASM) combined vegetable types, to predict the spatial patterns of soil antibiotics, using 100 surface soil samples collected from an intensive vegetable cultivation area located in east of China, and the fluoroquinolones (FQs), including ciprofloxacin (CFX), enrofloxacin (EFX) and norfloxacin (NFX), were analyzed as the target antibiotics. The results show that vegetable type is an effective factor to be combined to improve the interpolator performance. HASM achieves less mean absolute errors (MAEs) and root mean square errors (RMSEs) for total FQs (NFX+CFX+EFX), NFX, CFX and EFX than kriging with external drift (KED), stratified kriging (StK), ordinary kriging (OK) and inverse distance weighting (IDW). The MAE of HASM for FQs is 55.1 μg/kg, and the MAEs of KED, StK, OK and IDW are 99.0 μg/kg, 102.8 μg/kg, 106.3 μg/kg and 108.7 μg/kg, respectively. Further, RMSE simulated by HASM for FQs (CFX, EFX and NFX) are 106.2 μg/kg (88.6 μg/kg, 20.4 μg/kg and 39.2 μg/kg), and less 30% (27%, 22% and 36%), 33% (27%, 27% and 43%), 38% (34%, 23% and 41%) and 42% (32%, 35% and 51%) than the ones by KED, StK, OK and IDW, respectively. HASM also provides better maps with more details and more consistent maximum and minimum values of soil antibiotics compared with the measured data. The better performance can be concluded that HASM takes the vegetable type information as global approximate information, and takes local sampling data as its optimum control constraints.

  13. Modeling of biological nanostructured surfaces

    Science.gov (United States)

    Cristea, P. D.; Tuduce, Rodica; Arsene, O.; Dinca, Alina; Fulga, F.; Nicolau, D. V.

    2010-02-01

    The paper presents a methodology using atom or amino acid hydrophobicities to describe the surface properties of proteins in order to predict their interactions with other proteins and with artificial nanostructured surfaces. A standardized pattern is built around each surface atom of the protein for a radius depending on the molecule type and size. The atom neighborhood is characterized in terms of the hydrophobicity surface density. A clustering algorithm is used to classify the resulting patterns and to identify the possible interactions. The methodology has been implemented in a software package based on Java technology deployed in a Linux environment.

  14. Discrete Surface Modelling Using Partial Differential Equations.

    Science.gov (United States)

    Xu, Guoliang; Pan, Qing; Bajaj, Chandrajit L

    2006-02-01

    We use various nonlinear partial differential equations to efficiently solve several surface modelling problems, including surface blending, N-sided hole filling and free-form surface fitting. The nonlinear equations used include two second order flows, two fourth order flows and two sixth order flows. These nonlinear equations are discretized based on discrete differential geometry operators. The proposed approach is simple, efficient and gives very desirable results, for a range of surface models, possibly having sharp creases and corners.

  15. Laser surface processing and model studies

    CERN Document Server

    Yilbas, Bekir Sami

    2013-01-01

    This book introduces model studies associated with laser surface processing such as conduction limited heating, surface re-melting, Marangoni flow and its effects on the temperature field, re-melting of multi-layered surfaces, laser shock processing, and practical applications. The book provides insight into the physical processes involved with laser surface heating and phase change in laser irradiated region. It is written for engineers and researchers working on laser surface engineering.

  16. Surface Flux Modeling for Air Quality Applications

    Directory of Open Access Journals (Sweden)

    Limei Ran

    2011-08-01

    Full Text Available For many gasses and aerosols, dry deposition is an important sink of atmospheric mass. Dry deposition fluxes are also important sources of pollutants to terrestrial and aquatic ecosystems. The surface fluxes of some gases, such as ammonia, mercury, and certain volatile organic compounds, can be upward into the air as well as downward to the surface and therefore should be modeled as bi-directional fluxes. Model parameterizations of dry deposition in air quality models have been represented by simple electrical resistance analogs for almost 30 years. Uncertainties in surface flux modeling in global to mesoscale models are being slowly reduced as more field measurements provide constraints on parameterizations. However, at the same time, more chemical species are being added to surface flux models as air quality models are expanded to include more complex chemistry and are being applied to a wider array of environmental issues. Since surface flux measurements of many of these chemicals are still lacking, resistances are usually parameterized using simple scaling by water or lipid solubility and reactivity. Advances in recent years have included bi-directional flux algorithms that require a shift from pre-computation of deposition velocities to fully integrated surface flux calculations within air quality models. Improved modeling of the stomatal component of chemical surface fluxes has resulted from improved evapotranspiration modeling in land surface models and closer integration between meteorology and air quality models. Satellite-derived land use characterization and vegetation products and indices are improving model representation of spatial and temporal variations in surface flux processes. This review describes the current state of chemical dry deposition modeling, recent progress in bi-directional flux modeling, synergistic model development research with field measurements, and coupling with meteorological land surface models.

  17. Hydrophilic-Core Microcapsules and Their Formation

    Science.gov (United States)

    Calle, Luz M. (Inventor); Li, Wenyan (Inventor); Buhrow, Jerry W. (Inventor); Jolley, Scott T. (Inventor)

    2016-01-01

    Hydrophilic-core microcapsules and methods of their formation are provided. A hydrophilic-core microcapsule may include a shell that encapsulates water with the core substance dissolved or dispersed therein. The hydrophilic-core microcapsules may be formed from an emulsion having hydrophilic-phase droplets dispersed in a hydrophobic phase, with shell-forming compound contained in the hydrophilic phase or the hydrophobic phase and the core substance contained in the hydrophilic phase. The shells of the microcapsules may be capable of being broken down in response to being contacted by an alkali, e.g., produced during corrosion, contacting the shell.

  18. Alternative methods for estimating common descriptors for QSAR studies of dyes and fluorescent probes using molecular modeling software. 2. Correlations between log P and the hydrophilic/lipophilic index, and new methods for estimating degrees of amphiphilicity.

    Science.gov (United States)

    Dapson, Richard W; Horobin, Richard W

    2013-11-01

    The log P descriptor, despite its usefulness, can be difficult to use, especially for researchers lacking skills in physical chemistry. Moreover this classic measure has been determined in numerous ways, which can result in inconsistant estimates of log P values, especially for relatively complex molecules such as fluorescent probes. Novel measures of hydrophilicity/lipophilicity (the Hydrophilic/Lipophilic Index, HLI) and amphiphilicity (hydrophilic/lipophilic indices for the head group and tail, HLIT and HLIHG, respectively) therefore have been devised. We compare these descriptors with measures based on log P, the standard method for quantitative structure activity relationships (QSAR) studies. HLI can be determined using widely available molecular modeling software, coupled with simple arithmetic calculations. It is based on partial atomic charges and is intended to be a stand-alone measure of hydrophilicity/lipophilicity. Given the wide application of log P, however, we investigated the correlation between HLI and log P using a test set of 56 fluorescent probes of widely different physicochemical character. Overall correlation was poor; however, correlation of HLI and log P for probes of narrowly specified charge types, i.e., non-ionic compounds, anions, conjugated cations, or zwitterions, was excellent. Values for probes with additional nonconjugated quaternary cations, however, were less well correlated. The newly devised HLI can be divided into domain-specific descriptors, HLIT and HLIHG in amphiphilic probes. Determinations of amphiphilicity, made independently by the authors using their respective methods, showed excellent agreement. Quantifying amphiphilicity from partial log P values of the head group (head group hydrophilicity; HGH) and tail (amphiphilicity index; AI) has proved useful for understanding fluorescent probe action. The same limitations of log P apply to HGH and AI, however. The novel descriptors, HLIT and HLIHG, offer analogous advantages

  19. Dynamic Factor Models for the Volatility Surface

    DEFF Research Database (Denmark)

    van der Wel, Michel; Ozturk, Sait R.; Dijk, Dick van

    The implied volatility surface is the collection of volatilities implied by option contracts for different strike prices and time-to-maturity. We study factor models to capture the dynamics of this three-dimensional implied volatility surface. Three model types are considered to examine desirable...... features for representing the surface and its dynamics: a general dynamic factor model, restricted factor models designed to capture the key features of the surface along the moneyness and maturity dimensions, and in-between spline-based methods. Key findings are that: (i) the restricted and spline......-based models are both rejected against the general dynamic factor model, (ii) the factors driving the surface are highly persistent, (iii) for the restricted models option Delta is preferred over the more often used strike relative to spot price as measure for moneyness....

  20. Uncertainties in Surface Layer Modeling

    Science.gov (United States)

    Pendergrass, W.

    2015-12-01

    A central problem for micrometeorologists has been the relationship of air-surface exchange rates of momentum and heat to quantities that can be predicted with confidence. The flux-gradient profile developed through Monin-Obukhov Similarity Theory (MOST) provides an integration of the dimensionless wind shear expression where is an empirically derived expression for stable and unstable atmospheric conditions. Empirically derived expressions are far from universally accepted (Garratt, 1992, Table A5). Regardless of what form of these relationships might be used, their significance over any short period of time is questionable since all of these relationships between fluxes and gradients apply to averages that might rarely occur. It is well accepted that the assumption of stationarity and homogeneity do not reflect the true chaotic nature of the processes that control the variables considered in these relationships, with the net consequence that the levels of predictability theoretically attainable might never be realized in practice. This matter is of direct relevance to modern prognostic models which construct forecasts by assuming the universal applicability of relationships among averages for the lower atmosphere, which rarely maintains an average state. Under a Cooperative research and Development Agreement between NOAA and Duke Energy Generation, NOAA/ATDD conducted atmospheric boundary layer (ABL) research using Duke renewable energy sites as research testbeds. One aspect of this research has been the evaluation of legacy flux-gradient formulations (the ϕ functions, see Monin and Obukhov, 1954) for the exchange of heat and momentum. At the Duke Energy Ocotillo site, NOAA/ATDD installed sonic anemometers reporting wind and temperature fluctuations at 10Hz at eight elevations. From these observations, ϕM and ϕH were derived from a two-year database of mean and turbulent wind and temperature observations. From this extensive measurement database, using a

  1. Modeling surface imperfections in thin films and nanostructured surfaces

    DEFF Research Database (Denmark)

    Hansen, Poul-Erik; Madsen, J. S.; Jensen, S. A.

    2017-01-01

    Accurate scatterometry and ellipsometry characterization of non-perfect thin films and nanostructured surfaces are challenging. Imperfections like surface roughness make the associated modelling and inverse problem solution difficult due to the lack of knowledge about the imperfection on the surf......Accurate scatterometry and ellipsometry characterization of non-perfect thin films and nanostructured surfaces are challenging. Imperfections like surface roughness make the associated modelling and inverse problem solution difficult due to the lack of knowledge about the imperfection...... classes of imperfections are examined. The imperfections are introduced as periodic structures with a super cell periods ten times larger than the simple grating period. Two classes of imperfections concern the grating and one class concern the substrate. It is shown that imperfections of a few nanometers...

  2. Modeling for Standoff Surface Detection

    Science.gov (United States)

    2013-11-01

    Start Digi ” button (Figure 6) starts the Acqiris digitizer, and clicking on the “Stop Digi ” button stops the digitizer. The flow chart (Figure 7) shows...the algorithm used to collect data during this process. When the operator clicks the “Start Digi ” button, the Surface Detect software has a

  3. Different assembly of type IV collagen on hydrophilic and hydrophobic substrata alters endothelial cells interaction.

    Science.gov (United States)

    Coelho, N Miranda; González-García, C; Planell, J A; Salmerón-Sánchez, M; Altankov, G

    2010-06-09

    Considering the structural role of type IV collagen (Col IV) in the assembly of the basement membrane (BM) and the perspective of mimicking its organization for vascular tissue engineering purposes, we studied the adsorption pattern of this protein on model hydrophilic (clean glass) and hydrophobic trichloro(octadecyl)silane (ODS) surfaces known to strongly affect the behavior of other matrix proteins. The amount of fluorescently labeled Col IV was quantified showing saturation of the surface for concentration of the adsorbing solution of about 50microg/ml, but with approximately twice more adsorbed protein on ODS. AFM studies revealed a fine - nearly single molecular size - network arrangement of Col IV on hydrophilic glass, which turns into a prominent and growing polygonal network consisting of molecular aggregates on hydrophobic ODS. The protein layer forms within minutes in a concentration-dependent manner. We further found that human umbilical vein endothelial cells (HUVEC) attach less efficiently to the aggregated Col IV (on ODS), as judged by the significantly altered cell spreading, focal adhesions formation and the development of actin cytoskeleton. Conversely, the immunofluorescence studies for integrins revealed that the fine Col IV network formed on hydrophilic substrata is better recognized by the cells via both alpha1 and alpha2 heterodimers which support cellular interaction, apart from these on hydrophobic ODS where almost no clustering of integrins was observed.

  4. Different assembly of type IV collagen on hydrophilic and hydrophobic substrata alters endothelial cells interaction

    Directory of Open Access Journals (Sweden)

    NM Coelho

    2010-06-01

    Full Text Available Considering the structural role of type IV collagen (Col IV in the assembly of the basement membrane (BM and the perspective of mimicking its organization for vascular tissue engineering purposes, we studied the adsorption pattern of this protein on model hydrophilic (clean glass and hydrophobic trichloro(octadecylsilane (ODS surfaces known to strongly affect the behavior of other matrix proteins. The amount of fluorescently labeled Col IV was quantified showing saturation of the surface for concentration of the adsorbing solution of about 50μg/ml, but with approximately twice more adsorbed protein on ODS. AFM studies revealed a fine – nearly single molecular size – network arrangement of Col IV on hydrophilic glass, which turns into a prominent and growing polygonal network consisting of molecular aggregates on hydrophobic ODS. The protein layer forms within minutes in a concentration-dependent manner. We further found that human umbilical vein endothelial cells (HUVEC attach less efficiently to the aggregated Col IV (on ODS, as judged by the significantly altered cell spreading, focal adhesions formation and the development of actin cytoskeleton. Conversely, the immunofluorescence studies for integrins revealed that the fine Col IV network formed on hydrophilic substrata is better recognized by the cells via both α1 and α2 heterodimers which support cellular interaction, apart from these on hydrophobic ODS where almost no clustering of integrins was observed.

  5. Integral Models of Extremal Rational Elliptic Surfaces

    CERN Document Server

    Jarvis, Tyler J; Ricks, Jeremy R

    2009-01-01

    Miranda and Persson classified all extremal rational elliptic surfaces in characteristic zero. We show that each surface in Miranda and Persson's classification has an integral model with good reduction everywhere (except for those of type X_{11}(j), which is an exceptional case), and that every extremal rational elliptic surface over an algebraically closed field of characteristic p > 0 can be obtained by reducing one of these integral models mod p.

  6. Permeation of Hydrophilic Molecules across Glycated Skin Is Differentially Regulated by the Stratum Corneum and Epidermis-Dermis.

    Science.gov (United States)

    Yokota, Mami; Tokudome, Yoshihiro

    2015-01-01

    The effects of glycation on skin permeation and accumulation of compounds were evaluated using an in vitro glycated skin model. Glycation of the skin of hairless mice was induced using vertical diffusion cells and incubation with phosphate-buffered saline containing 50 mM glyoxal for 24 h. Flux and accumulation in the skin were determined by applying hydrophilic and lipophilic molecules (Sodium fluorescein; FL-Na and Nile red, respectively) to this in vitro glycated skin model. Furthermore, to investigate the effect of glycation on epidermal-dermal barrier properties, we conducted diffusion experiments with FL-Na and fluorescein isothiocyanate-dextran using stratum corneum (SC)-stripped glycated skin. The in vitro glycated skin model demonstrated characteristic glycation alterations like a yellowish change in skin color and surface roughness. For low-molecular weight (MW) hydrophilic molecules, flux across glycated full-thickness skin was higher than that across normal skin, although there was no difference with lipophilic molecules. However, glycated epidermis-dermis showed lower flux, and the difference increased with the MW of the compound. Furthermore, the amount of high-MW hydrophilic molecules accumulated in glycated epidermis-dermis was decreased. These results suggest that glycated SC and epidermis-dermis differentially regulate the permeability of hydrophilic molecules and highlight the importance of controlling drug delivery by modifying the formulation or method of application depending on skin condition.

  7. Deformable surface modeling based on dual subdivision

    Institute of Scientific and Technical Information of China (English)

    WANG Huawei; SUN Hanqiu; QIN Kaihuai

    2005-01-01

    Based on dual Doo-Sabin subdivision and the corresponding parameterization, a modeling technique of deformable surfaces is presented in this paper. In the proposed model, all the dynamic parameters are computed in a unified way for both non-defective and defective subdivision matrices, and central differences are used to discretize the Lagrangian dynamics equation instead of backward differences. Moreover, a local scheme is developed to solve the dynamics equation approximately, thus the order of the linear equation is reduced greatly. Therefore, the proposed model is more efficient and faster than the existing dynamic models. It can be used for deformable surface design, interactive surface editing, medical imaging and simulation.

  8. Digital Modeling Phenomenon Of Surface Ground Movement

    Directory of Open Access Journals (Sweden)

    Ioan Voina

    2016-11-01

    Full Text Available With the development of specialized software applications it was possible to approach and resolve complex problems concerning automating and process optimization for which are being used field data. Computerized representation of the shape and dimensions of the Earth requires a detailed mathematical modeling, known as "digital terrain model". The paper aims to present the digital terrain model of Vulcan mining, Hunedoara County, Romania. Modeling consists of a set of mathematical equations that define in detail the surface of Earth and has an approximate surface rigorously and mathematical, that calculated the land area. Therefore, the digital terrain model means a digital representation of the earth's surface through a mathematical model that approximates the land surface modeling, which can be used in various civil and industrial applications in. To achieve the digital terrain model of data recorded using linear and nonlinear interpolation method based on point survey which highlights the natural surface studied. Given the complexity of this work it is absolutely necessary to know in detail of all topographic elements of work area, without the actions to be undertaken to project and manipulate would not be possible. To achieve digital terrain model, within a specialized software were set appropriate parameters required to achieve this case study. After performing all steps we obtained digital terrain model of Vulcan Mine. Digital terrain model is the complex product, which has characteristics that are equivalent to the specialists that use satellite images and information stored in a digital model, this is easier to use.

  9. Modeling of global surface air temperature

    Science.gov (United States)

    Gusakova, M. A.; Karlin, L. N.

    2012-04-01

    A model to assess a number of factors, such as total solar irradiance, albedo, greenhouse gases and water vapor, affecting climate change has been developed on the basis of Earth's radiation balance principle. To develop the model solar energy transformation in the atmosphere was investigated. It's a common knowledge, that part of the incoming radiation is reflected into space from the atmosphere, land and water surfaces, and another part is absorbed by the Earth's surface. Some part of outdoing terrestrial radiation is retained in the atmosphere by greenhouse gases (carbon dioxide, methane, nitrous oxide) and water vapor. Making use of the regression analysis a correlation between concentration of greenhouse gases, water vapor and global surface air temperature was obtained which, it is turn, made it possible to develop the proposed model. The model showed that even smallest fluctuations of total solar irradiance intensify both positive and negative feedback which give rise to considerable changes in global surface air temperature. The model was used both to reconstruct the global surface air temperature for the 1981-2005 period and to predict global surface air temperature until 2030. The reconstructions of global surface air temperature for 1981-2005 showed the models validity. The model makes it possible to assess contribution of the factors listed above in climate change.

  10. Model on surface borehole squeezing deformation fracture*

    Institute of Scientific and Technical Information of China (English)

    SUN Hai-tao; HU Qian-ting; HUANG Sheng-shu

    2009-01-01

    As a good method to solve the problem of high methane on the workface and in the goaf, drawing coal strata methane through a surface borehole is used. However, the excavation affected the overlying rock strata greatly. When the excavation face passed through the surface borehole position, the surface borehole fractures fast. This problem was seriously related to the unformed squeeze effect. Therefore, a squeezing deformation fracture model based on the rock strata squeezing effect was set up. At the same time, a 3DEC simulation model is presented to confirm the theory. The result shows that the mod-el is reliable and has a good engineering application value.

  11. Generalized Models for Rock Joint Surface Shapes

    Directory of Open Access Journals (Sweden)

    Shigui Du

    2014-01-01

    Full Text Available Generalized models of joint surface shapes are the foundation for mechanism studies on the mechanical effects of rock joint surface shapes. Based on extensive field investigations of rock joint surface shapes, generalized models for three level shapes named macroscopic outline, surface undulating shape, and microcosmic roughness were established through statistical analyses of 20,078 rock joint surface profiles. The relative amplitude of profile curves was used as a borderline for the division of different level shapes. The study results show that the macroscopic outline has three basic features such as planar, arc-shaped, and stepped; the surface undulating shape has three basic features such as planar, undulating, and stepped; and the microcosmic roughness has two basic features such as smooth and rough.

  12. Restricted access molecularly imprinted polymers obtained by bovine serum albumin and/or hydrophilic monomers' external layers: a comparison related to physical and chemical properties.

    Science.gov (United States)

    Santos, Mariane Gonçalves; Moraes, Gabriel de Oliveira Isac; Nakamura, Maurício Gustavo; dos Santos-Neto, Álvaro José; Figueiredo, Eduardo Costa

    2015-11-21

    Molecularly imprinting polymers (MIPs) can be modified with external layers in order to obtain restricted access molecularly imprinted polymers (RAMIPs) able to exclude macromolecules and retain low weight compounds. These modifications have been frequently achieved using hydrophilic monomers, chemically bound on the MIP surface. Recently, our group proposed a new biocompatible RAMIP based on the formation of a bovine serum albumin coating on the surface of MIP particles. This material has been used to extract drugs directly from untreated human plasma samples, but its physicochemical evaluation has not been carried out yet, mainly in comparison with RAMIPs obtained by hydrophilic monomers. Thus, we proposed in this paper a comparative study involving the surface composition, microscopic aspect, selectivity, binding kinetics, adsorption and macromolecule elimination ability of these different materials. We concluded that the synthesis procedure influences the size and shape of particles and that hydrophilic co-monomer addition as well as coating with BSA do not alter the chemical recognition ability of the material. The difference between imprinted and non-imprinted polymers' adsorption was evident (suggesting that imprinted polymers have a better capacity to bind the template than the non-imprinted ones). The Langmuir model presents the best fit to describe the materials' adsorption profile. The polymer covered with hydrophilic monomers presented the best adsorption for the template in an aqueous medium, probably due to a hydrophilic layer on its surface. We also concluded that an association of the hydrophilic monomers with the bovine serum albumin coating is important to obtain materials with higher capacity of macromolecule exclusion.

  13. Shallow Water Propagation and Surface Reverberation Modeling

    Science.gov (United States)

    2014-07-29

    term goals were to 1. exploit measurements of breaking wave noise and photographic images of whitecaps to infer bubble cloud populations at the sea ...surface reverberation in wind-driven seas , an additional objective has been to study the role of sub-surface bubbles on the attenuation and scattering of...acoustic signals, including determining methods for quantifying bubble populations with video footage of the sea surface and developing models of

  14. An Improved MUSIC Model for Gibbsite Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, Scott C.; Bickmore, Barry R.; Tadanier, Christopher J.; Rosso, Kevin M.

    2004-06-01

    Here we use gibbsite as a model system with which to test a recently published, bond-valence method for predicting intrinsic pKa values for surface functional groups on oxides. At issue is whether the method is adequate when valence parameters for the functional groups are derived from ab initio structure optimization of surfaces terminated by vacuum. If not, ab initio molecular dynamics (AIMD) simulations of solvated surfaces (which are much more computationally expensive) will have to be used. To do this, we had to evaluate extant gibbsite potentiometric titration data that where some estimate of edge and basal surface area was available. Applying BET and recently developed atomic force microscopy methods, we found that most of these data sets were flawed, in that their surface area estimates were probably wrong. Similarly, there may have been problems with many of the titration procedures. However, one data set was adequate on both counts, and we applied our method of surface pKa int prediction to fitting a MUSIC model to this data with considerable success—several features of the titration data were predicted well. However, the model fit was certainly not perfect, and we experienced some difficulties optimizing highly charged, vacuum-terminated surfaces. Therefore, we conclude that we probably need to do AIMD simulations of solvated surfaces to adequately predict intrinsic pKa values for surface functional groups.

  15. Assembly of citrate gold nanoparticles on hydrophilic monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Vikholm-Lundin, Inger, E-mail: inger.vikholm-lundin@uta.fi [University of Tampere, BioMediTech, Tampere (Finland); Fimlab Laboratories Ltd., Tampere (Finland); Rosqvist, Emil; Ihalainen, Petri [Abo Akademi University, Center for Functional Materials, Laboratory of Physical Chemistry (Finland); Munter, Tony [VTT Technical Research Centre of Finland, Process Chemistry end Environmental Engineering, Tampere (Finland); Honkimaa, Anni [University of Tampere, Department of Virology, School of Medicine, Tampere (Finland); Marjomäki, Varpu [University of Jyväskylä, Department of Biological and Environmental Science, Nanoscience Center, Jyväskylä (Finland); Albers, Willem M. [BioNavis Oy Ltd., Ylöjärvi, Tampere (Finland); Peltonen, Jouko [Abo Akademi University, Center for Functional Materials, Laboratory of Physical Chemistry (Finland)

    2016-08-15

    Highlights: • The self-assembled layers were all hydrophilic with Lipa-pTHMMAA exhibiting close to full wetting. • The polyacrylamide layers smoothen the gold surface to a higher extent than the polyethylene glycol and lipoic acid terminated with an amino group. • SPR resonance curves shift to higher angles and become increasingly damped when large nanoparticles assembled on the surface. • Topographical images confirmed that the highest number of particles were assembled on the polyethylene glycol monolayer. • By increasing the interaction time more particles could be assembled on the surface. - Abstract: Self-assembled monolayers (SAMs) as model surfaces were linked onto planar gold films thorough lipoic acid or disulfide groups. The molecules used were polyethylene glycol (EG-S-S), N-[tris-(hydroxymethyl)methyl]acrylamide polymers with and without lipoic acid (Lipa-pTHMMAA and pTHMMAA) and a lipoic acid triazine derivative (Lipa-MF). All the layers, but Lipa-MF with a primary amino group were hydroxyl terminated. The layers were characterized by contact angle measurements and atomic force microscopy, AFM. Citrate stabilized nanoparticles, AuNPs in water and phosphate buffer were allowed to assemble on the layers for 10 min and the binding was followed in real-time with surface plasmon resonance, SPR. The SPR resonance curves were observed to shift to higher angles and become increasingly damped, while also the peaks strongly broaden when large nanoparticles assembled on the surface. Both the angular shift and the damping of the curve was largest for nanoparticles assembling on the EG-S-S monolayer. High amounts of particles were also assembled on the pTHMMAA layer without the lipoic acid group, but the damping of the curve was considerably lower with a more even distribution of the particles. Topographical images confirmed that the highest number of particles were assembled on the polyethylene glycol monolayer. By increasing the interaction time more

  16. The XXZ Heisenberg model on random surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ambjørn, J., E-mail: ambjorn@nbi.dk [The Niels Bohr Institute, Copenhagen University, Blegdamsvej 17, DK-2100 Copenhagen (Denmark); Institute for Mathematics, Astrophysics and Particle Physics (IMAPP), Radbaud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen (Netherlands); Sedrakyan, A., E-mail: sedrak@nbi.dk [The Niels Bohr Institute, Copenhagen University, Blegdamsvej 17, DK-2100 Copenhagen (Denmark); Yerevan Physics Institute, Br. Alikhanyan str. 2, Yerevan-36 (Armenia)

    2013-09-21

    We consider integrable models, or in general any model defined by an R-matrix, on random surfaces, which are discretized using random Manhattan lattices. The set of random Manhattan lattices is defined as the set dual to the lattice random surfaces embedded on a regular d-dimensional lattice. They can also be associated with the random graphs of multiparticle scattering nodes. As an example we formulate a random matrix model where the partition function reproduces the annealed average of the XXZ Heisenberg model over all random Manhattan lattices. A technique is presented which reduces the random matrix integration in partition function to an integration over their eigenvalues.

  17. The XXZ Heisenberg model on random surfaces

    CERN Document Server

    Ambjorn, J

    2013-01-01

    We consider integrable models, or in general any model defined by an $R$-matrix, on random surfaces, which are discretized using random Manhattan lattices. The set of random Manhattan lattices is defined as the set dual to the lattice random surfaces embedded on a regular d-dimensional lattice. They can also be associated with the random graphs of multiparticle scattering nodes. As an example we formulate a random matrix model where the partition function reproduces the annealed average of the XXZ Heisenberg model over all random Manhattan lattices. A technique is presented which reduces the random matrix integration in partition function to an integration over their eigenvalues.

  18. Sonochemical synthesis of versatile hydrophilic magnetite nanoparticles.

    Science.gov (United States)

    Marchegiani, G; Imperatori, P; Mari, A; Pilloni, L; Chiolerio, A; Allia, P; Tiberto, P; Suber, L

    2012-07-01

    Hydrophilic magnetite nanoparticles in the size range 30-10nm are easily and rapidly prepared under ultrasonic irradiation of Fe(OH)(2) in di- and tri-ethylene glycol/water solution with volume ratio varying between 7:3 and 3:7. Structural (XRD) and morphological (SEM) characterization reveal good crystalline and homogeneous particles whereas, when solvothermally prepared, the particles are inhomogeneous and aggregated. The sonochemically prepared particles are versatile, i.e. well suited to covalently bind molecules because of the free glycol hydroxylic groups on their surface or exchange the diethylene or triethylene glycol ligand. They can be easily transferred in hydrophobic solvents too. Room-temperature magnetic hysteresis properties measured by means of Vibrating Sample Magnetometer (VSM) display a nearly superparamagnetic character. The sonochemical preparation is easily scalable to meet industrial demand. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Impacts of hydrophilic colanic acid on bacterial attachment to microfiltration membranes and subsequent membrane biofouling.

    Science.gov (United States)

    Yoshida, Keitaro; Tashiro, Yosuke; May, Thithiwat; Okabe, Satoshi

    2015-06-01

    In order to examine the interactions between physicochemical properties of specific extracellular polymeric substances (EPS) and membrane biofouling, we investigated the impacts of hydrophilic colanic acid, as a model extracellular polysaccharide component, on initial bacterial attachment to different microfiltration (MF) membranes and membrane biofouling by using Escherichia coli strains producing different amounts of colanic acid. In a newly designed microtiter plate assay, the bacterial attachment by an E. coli strain RcsF(+), which produces massive amounts of colanic acid, decreased only to a hydrophobic membrane because the colanic acid made cell surfaces more hydrophilic, resulting in low cell attachment to hydrophobic membranes. The bench-scale cross-flow filtration tests followed by filtration resistance measurement revealed that RcsF(+) caused severe irreversible membrane fouling (i.e., pore-clogging), whereas less extracellular polysaccharide-producing strains caused moderate but reversible fouling to all membranes used in this study. Further cross-flow filtration tests indicated that colanic acid liberated in the bulk phase could rapidly penetrate pre-accumulated biomass layers (i.e., biofilms) and then directly clogged membrane pores. These results indicate that colanic acid, a hydrophilic extracellular polysaccharide, and possible polysaccharides with similar characteristics with colanic acid are considered as a major cause of severe irreversible membrane fouling (i.e., pore-clogging) regardless of biofilm formation (dynamic membrane).

  20. Modeling surface imperfections in thin films and nanostructured surfaces

    Science.gov (United States)

    Hansen, P.-E.; Madsen, J. S.; Jensen, S. A.; Madsen, M. H.; Karamehmedovic, M.

    2017-06-01

    Accurate scatterometry and ellipsometry characterization of non-perfect thin films and nanostructured surfaces are challenging. Imperfections like surface roughness make the associated modelling and inverse problem solution difficult due to the lack of knowledge about the imperfection on the surface. Combining measurement data from several instruments increases the knowledge of non-perfect surfaces. In this paper we investigate how to incorporate this knowledge of surface imperfection into inverse methods used in scatterometry and ellipsometry using the Rigorous Coupled Wave Analysis. Three classes of imperfections are examined. The imperfections are introduced as periodic structures with a super cell periods ten times larger than the simple grating period. Two classes of imperfections concern the grating and one class concern the substrate. It is shown that imperfections of a few nanometers can severely change the reflective response on silicon gratings. Inverse scatterometry analyses of gratings with imperfection using simulated data with white noise have been performed. The results show that scatterometry is a robust technology that is able to characterize grating imperfections provided that the imperfection class is known.

  1. Minimal model for spoof acoustoelastic surface states

    Energy Technology Data Exchange (ETDEWEB)

    Christensen, J., E-mail: jochri@fotonik.dtu.dk; Willatzen, M. [Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Liang, Z. [College of Electronic Science and Technology, Shenzhen University, Shenzhen (China)

    2014-12-15

    Similar to textured perfect electric conductors for electromagnetic waves sustaining artificial or spoof surface plasmons we present an equivalent phenomena for the case of sound. Aided by a minimal model that is able to capture the complex wave interaction of elastic cavity modes and airborne sound radiation in perfect rigid panels, we construct designer acoustoelastic surface waves that are entirely controlled by the geometrical environment. Comparisons to results obtained by full-wave simulations confirm the feasibility of the model and we demonstrate illustrative examples such as resonant transmissions and waveguiding to show a few examples of many where spoof elastic surface waves are useful.

  2. Minimal model for spoof acoustoelastic surface states

    Directory of Open Access Journals (Sweden)

    J. Christensen

    2014-12-01

    Full Text Available Similar to textured perfect electric conductors for electromagnetic waves sustaining artificial or spoof surface plasmons we present an equivalent phenomena for the case of sound. Aided by a minimal model that is able to capture the complex wave interaction of elastic cavity modes and airborne sound radiation in perfect rigid panels, we construct designer acoustoelastic surface waves that are entirely controlled by the geometrical environment. Comparisons to results obtained by full-wave simulations confirm the feasibility of the model and we demonstrate illustrative examples such as resonant transmissions and waveguiding to show a few examples of many where spoof elastic surface waves are useful.

  3. Modeling and simulation of surface roughness

    Energy Technology Data Exchange (ETDEWEB)

    Patrikar, Rajendra M

    2004-04-30

    With the technology advancement, electronic devices are miniaturized at every development node. Physical parameters such as microscopic roughness are affecting these devices because surface to volume ratio is increasing rapidly. On all the real surfaces microscopic roughness appears, which affects many electronic properties of the material, which in turn decides the yield and reliability of the devices. Different type of parameters and simulation methods are used to describe the surface roughness. Classically surface roughness was modeled by methods such as power series and Fast Fourier Transform (FFT). Limitations of this methods lead to use the concept of self-similar fractals to model the rough surface through Mandelbrot-Weierstrass function. It is difficult to express surface roughness as a function of process parameters in the form of analytical functions. Method based on neural networks has been used to model these surfaces to map the process parameters to roughness parameters. Finally, change in electrical parameters such as capacitance, resistance and noise due to surface roughness has been computed by numerical methods.

  4. Foundations of elastoplasticity subloading surface model

    CERN Document Server

    Hashiguchi, Koichi

    2017-01-01

    This book is the standard text book of elastoplasticity in which the elastoplasticity theory is comprehensively described from the conventional theory for the monotonic loading to the unconventional theory for the cyclic loading behavior. Explanations of vector-tensor analysis and continuum mechanics are provided first as a foundation for elastoplasticity theory, covering various strain and stress measures and their rates with their objectivities. Elastoplasticity has been highly developed by the creation and formulation of the subloading surface model which is the unified fundamental law for irreversible mechanical phenomena in solids. The assumption that the interior of the yield surface is an elastic domain is excluded in order to describe the plastic strain rate due to the rate of stress inside the yield surface in this model aiming at the prediction of cyclic loading behavior, although the yield surface enclosing the elastic domain is assumed in all the elastoplastic models other than the subloading surf...

  5. Uncertainty and Sensitivity in Surface Dynamics Modeling

    Science.gov (United States)

    Kettner, Albert J.; Syvitski, James P. M.

    2016-05-01

    Papers for this special issue on 'Uncertainty and Sensitivity in Surface Dynamics Modeling' heralds from papers submitted after the 2014 annual meeting of the Community Surface Dynamics Modeling System or CSDMS. CSDMS facilitates a diverse community of experts (now in 68 countries) that collectively investigate the Earth's surface-the dynamic interface between lithosphere, hydrosphere, cryosphere, and atmosphere, by promoting, developing, supporting and disseminating integrated open source software modules. By organizing more than 1500 researchers, CSDMS has the privilege of identifying community strengths and weaknesses in the practice of software development. We recognize, for example, that progress has been slow on identifying and quantifying uncertainty and sensitivity in numerical modeling of earth's surface dynamics. This special issue is meant to raise awareness for these important subjects and highlight state-of-the-art progress.

  6. Neutral hydrophilic cathode catalyst binders for microbial fuel cells

    KAUST Repository

    Saito, Tomonori

    2011-01-01

    Improving oxygen reduction in microbial fuel cell (MFC) cathodes requires a better understanding of the effects of the catalyst binder chemistry and properties on performance. A series of polystyrene-b-poly(ethylene oxide) (PS-b-PEO) polymers with systematically varying hydrophilicity were designed to determine the effect of the hydrophilic character of the binder on cathode performance. Increasing the hydrophilicity of the PS-b-PEO binders enhanced the electrochemical response of the cathode and MFC power density by ∼15%, compared to the hydrophobic PS-OH binder. Increased cathode performance was likely a result of greater water uptake by the hydrophilic binder, which would increase the accessible surface area for oxygen reduction. Based on these results and due to the high cost of PS-b-PEO, the performance of an inexpensive hydrophilic neutral polymer, poly(bisphenol A-co-epichlorohydrin) (BAEH), was examined in MFCs and compared to a hydrophilic sulfonated binder (Nafion). MFCs with BAEH-based cathodes with two different Pt loadings initially (after 2 cycles) had lower MFC performance (1360 and 630 mW m-2 for 0.5 and 0.05 mg Pt cm-2) than Nafion cathodes (1980 and 1080 mW m -2 for 0.5 and 0.05 mg Pt cm-2). However, after long-term operation (22 cycles, 40 days), power production of each cell was similar (∼1200 and 700-800 mW m-2 for 0.5 and 0.05 mg Pt cm-2) likely due to cathode biofouling that could not be completely reversed through physical cleaning. While binder chemistry could improve initial electrochemical cathode performance, binder materials had less impact on overall long-term MFC performance. This observation suggests that long-term operation of MFCs will require better methods to avoid cathode biofouling. © 2011 The Royal Society of Chemistry.

  7. Computer Modelling of 3D Geological Surface

    CERN Document Server

    Kodge, B G

    2011-01-01

    The geological surveying presently uses methods and tools for the computer modeling of 3D-structures of the geographical subsurface and geotechnical characterization as well as the application of geoinformation systems for management and analysis of spatial data, and their cartographic presentation. The objectives of this paper are to present a 3D geological surface model of Latur district in Maharashtra state of India. This study is undertaken through the several processes which are discussed in this paper to generate and visualize the automated 3D geological surface model of a projected area.

  8. Residence time dependent desorption of Staphylococcus epidermidis from hydrophobic and hydrophilic substrata.

    Science.gov (United States)

    Boks, Niels P; Kaper, Hans J; Norde, Willem; Busscher, Henk J; van der Mei, Henny C

    2008-12-01

    Adhesion and desorption are simultaneous events during bacterial adhesion to surfaces, although desorption is far less studied than adhesion. Here, desorption of Staphylococcus epidermidis from substratum surfaces is demonstrated to be residence time dependent. Initial desorption rate coefficients were similar for hydrophilic and hydrophobic dimethyldichlorosilane (DDS)-coated glass, likely because initial desorption is controlled by attractive Lifshitz-Van der Waals interactions, which are comparable on both substratum surfaces. However, significantly slower decay times of the desorption rate coefficients are found for hydrophilic glass than for hydrophobic DDS-coated glass. This difference is suggested to be due to the acid-base interactions between staphylococci and these surfaces, which are repulsive on hydrophilic glass and attractive on hydrophobic DDS-coated glass. Final desorption rate coefficients are higher on hydrophilic glass than on hydrophobic DDS-coated glass, due to the so called hydrophobic effect, facilitating a closer contact on hydrophobic DDS-coated glass.

  9. Liquid surface model for carbon nanotube energetics

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Mathew, Maneesh; Solov'yov, Andrey V.

    2008-01-01

    In the present paper we developed a model for calculating the energy of single-wall carbon nanotubes of arbitrary chirality. This model, which we call as the liquid surface model, predicts the energy of a nanotube with relative error less than 1% once its chirality and the total number of atoms...... are known. The parameters of the liquid surface model and its potential applications are discussed. The model has been suggested for open end and capped nanotubes. The influence of the catalytic nanoparticle, atop which nanotubes grow, on the nanotube stability is also discussed. The suggested model gives...... an important insight in the energetics and stability of nanotubes of different chirality and might be important for the understanding of nanotube growth process. For the computations we use empirical Brenner and Tersoff potentials and discuss their applicability to the study of carbon nanotubes. From...

  10. Land-surface modelling in hydrological perspective

    DEFF Research Database (Denmark)

    Overgaard, Jesper; Rosbjerg, Dan; Butts, M.B.

    2006-01-01

    The purpose of this paper is to provide a review of the different types of energy-based land-surface models (LSMs) and discuss some of the new possibilities that will arise when energy-based LSMs are combined with distributed hydrological modelling. We choose to focus on energy-based approaches, ......, and the difficulties inherent in various evaluation procedures are presented. Finally, the dynamic coupling of hydrological and atmospheric models is explored, and the perspectives of such efforts are discussed....

  11. Liquid surface model for carbon nanotube energetics

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Mathew, Maneesh; Solov'yov, Andrey V.

    2008-01-01

    In the present paper we developed a model for calculating the energy of single-wall carbon nanotubes of arbitrary chirality. This model, which we call as the liquid surface model, predicts the energy of a nanotube with relative error less than 1% once its chirality and the total number of atoms...... the calculated energies we determine the elastic properties of the single-wall carbon nanotubes (Young modulus, curvature constant) and perform a comparison with available experimental measurements and earlier theoretical predictions....

  12. Land-surface modelling in hydrological perspective

    DEFF Research Database (Denmark)

    Overgaard, Jesper; Rosbjerg, Dan; Butts, M.B.

    2006-01-01

    The purpose of this paper is to provide a review of the different types of energy-based land-surface models (LSMs) and discuss some of the new possibilities that will arise when energy-based LSMs are combined with distributed hydrological modelling. We choose to focus on energy-based approaches......, and the difficulties inherent in various evaluation procedures are presented. Finally, the dynamic coupling of hydrological and atmospheric models is explored, and the perspectives of such efforts are discussed....

  13. A flow chamber assay for quantitative evaluation of bacterial surface colonization used to investigate the influence of temperature and surface hydrophilicity on the biofilm forming capacity of uropathogenic Escherichia coli

    DEFF Research Database (Denmark)

    Andersen, Thomas Emil; Kingshott, Peter; Palarasah, Yaseelan

    2010-01-01

    We have established a simple flow chamber-based procedure which provides an accurate and reproducible way to measure the amount of biofilm formed on an implantable biomaterial surface. The method enables the side-by-side evaluation of different materials under hydrodynamic flow conditions similar...

  14. Radiative transfer modeling of surface chemical deposits

    Science.gov (United States)

    Reichardt, Thomas A.; Kulp, Thomas J.

    2016-05-01

    Remote detection of a surface-bound chemical relies on the recognition of a pattern, or "signature," that is distinct from the background. Such signatures are a function of a chemical's fundamental optical properties, but also depend upon its specific morphology. Importantly, the same chemical can exhibit vastly different signatures depending on the size of particles composing the deposit. We present a parameterized model to account for such morphological effects on surface-deposited chemical signatures. This model leverages computational tools developed within the planetary and atmospheric science communities, beginning with T-matrix and ray-tracing approaches for evaluating the scattering and extinction properties of individual particles based on their size and shape, and the complex refractive index of the material itself. These individual-particle properties then serve as input to the Ambartsumian invariant imbedding solution for the reflectance of a particulate surface composed of these particles. The inputs to the model include parameters associated with a functionalized form of the particle size distribution (PSD) as well as parameters associated with the particle packing density and surface roughness. The model is numerically inverted via Sandia's Dakota package, optimizing agreement between modeled and measured reflectance spectra, which we demonstrate on data acquired on five size-selected silica powders over the 4-16 μm wavelength range. Agreements between modeled and measured reflectance spectra are assessed, while the optimized PSDs resulting from the spectral fitting are then compared to PSD data acquired from independent particle size measurements.

  15. Modeling the effect of dynamic surfaces on membrane penetration

    Science.gov (United States)

    van Lehn, Reid; Alexander-Katz, Alfredo

    2011-03-01

    The development of nanoscale materials for targeted drug delivery is an important current pursuit in materials science. One task of drug carriers is to release therapeutic agents within cells by bypassing the cell membrane to maximize the effectiveness of their payload and minimize bodily exposure. In this work, we use coarse-grained simulations to study nanoparticles (NPs) grafted with hydrophobic and hydrophilic ligands that rearrange in response to the amphiphilic lipid bilayer. We demonstrate that this dynamic surface permits the NP to spontaneously penetrate to the bilayer midplane when the surface ligands are near an order-disorder transition. We believe that this work will lead to the design of new drug carriers capable of non-specifically accessing cell interiors based solely on their dynamic surface properties. Our work is motivated by existing nanoscale systems such as micelles, or NPs grafted with highly mobile ligands or polymer brushes.

  16. Improving Drug Loading of Mucosal Solvent Cast Films Using a Combination of Hydrophilic Polymers with Amoxicillin and Paracetamol as Model Drugs

    Directory of Open Access Journals (Sweden)

    Joshua Boateng

    2013-01-01

    Full Text Available Solvent cast mucosal films with improved drug loading have been developed by combining carboxymethyl cellulose (CMC, sodium alginate (SA, and carrageenan (CAR using paracetamol and amoxicillin as model drugs and glycerol (GLY as plasticizer. Films were characterized using X-ray powder diffraction (XRPD, scanning electron microscopy (SEM, folding resilience, swelling capacity, mucoadhesivity, and drug dissolution studies. SA, CMC, and GLY (5 : 3 : 6 films showed maximum amoxicillin loading of 26.3% whilst CAR, CMC, and GLY (1 : 2 : 3 films had a maximum paracetamol loading of 40%. XRPD analysis showed different physical forms of the drugs depending on the amount loaded. Films containing 29.4% paracetamol and 26.3% amoxicillin showed molecular dispersion of the drugs while excess paracetamol was observed on the film surface when the maximum 40% was loaded. Work of adhesion was similar for blank films with slightly higher cohesiveness for CAR and CMC based films, but the differences were significant between paracetamol and amoxicillin containing films. The stickiness and cohesiveness for drug loaded films were generally similar with no significant differences. The maximum percentage cumulative drug release was 84.65% and 70.59% for paracetamol and amoxicillin, respectively, with anomalous case two transport mechanism involving both drug diffusion and polymer erosion.

  17. Minimal model for spoof acoustoelastic surface states

    DEFF Research Database (Denmark)

    Christensen, Johan; Liang, Z.; Willatzen, Morten

    2014-01-01

    Similar to textured perfect electric conductors for electromagnetic waves sustaining artificial or spoof surface plasmons we present an equivalent phenomena for the case of sound. Aided by a minimal model that is able to capture the complex wave interaction of elastic cavity modes and airborne...... sound radiation in perfect rigid panels, we construct designer acoustoelastic surface waves that are entirely controlled by the geometrical environment. Comparisons to results obtained by full-wave simu- lations confirm the feasibility of the model and we demonstrate illustrative examples...

  18. Modeling of Droplet Evaporation on Superhydrophobic Surfaces.

    Science.gov (United States)

    Fernandes, Heitor C M; Vainstein, Mendeli H; Brito, Carolina

    2015-07-14

    When a drop of water is placed on a rough surface, there are two possible extreme regimes of wetting: the one called Cassie-Baxter (CB) with air pockets trapped underneath the droplet and the one called the Wenzel (W) state characterized by the homogeneous wetting of the surface. A way to investigate the transition between these two states is by means of evaporation experiments, in which the droplet starts in a CB state and, as its volume decreases, penetrates the surface's grooves, reaching a W state. Here we present a theoretical model based on the global interfacial energies for CB and W states that allows us to predict the thermodynamic wetting state of the droplet for a given volume and surface texture. We first analyze the influence of the surface geometric parameters on the droplet's final wetting state with constant volume and show that it depends strongly on the surface texture. We then vary the volume of the droplet, keeping the geometric surface parameters fixed to mimic evaporation and show that the drop experiences a transition from the CB to the W state when its volume reduces, as observed in experiments. To investigate the dependency of the wetting state on the initial state of the droplet, we implement a cellular Potts model in three dimensions. Simulations show very good agreement with theory when the initial state is W, but it disagrees when the droplet is initialized in a CB state, in accordance with previous observations which show that the CB state is metastable in many cases. Both simulations and the theoretical model can be modified to study other types of surfaces.

  19. Preparation and characterization of dopamine-decorated hydrophilic carbon black

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Lijun; Lu Yonglai [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing 100029 (China); Wang Yiqing [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing 100029 (China); Zhang Liqun [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Key Laboratory of Beijing City on Preparation and Processing of Novel Polymer Materials, Beijing 100029 (China); Wang Wencai, E-mail: wangw@mail.buct.edu.cn [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China); Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing 100029 (China)

    2012-05-01

    Inspired by the bio-adhesive proteins secreted by mussels for attachment to almost all wet substrates, a facile method involving oxidative polymerization of dopamine was proposed to prepare highly hydrophilic carbon black (CB) particles. A self-assembled polydopamine (PDA) ad-layer was formed via the oxidative polymerization of dopamine on the surface of CB simply by dipping the CB into an alkaline dopamine solution and mildly stirring at room temperature. The process is simple, controllable, and environment-friendly. The surface composition and structure of the CB were characterized by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The surface morphology of the CB was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results showed that the PDA ad-layer was successfully deposited on the CB surfaces. The PDA-functionalized CB (CB-PDA) gave a stable colloidal dispersion in water. Contact angle measurement results indicated that the hydrophilicity of CB was significantly improved after dopamine modification. TGA results confirmed that the modified CB maintained good heat resistance. The method provided a facile route to prepare hydrophilic CB having terminal hydroxyl groups.

  20. Modeling Land Surface Phenology Using Earthlight

    Science.gov (United States)

    Henebry, G. M.

    2005-12-01

    Microwave radiometers have long been used in earth observation, but the coarse spatial resolution of the data has discouraged its use in investigations of the vegetated land surface. The Advanced Microwave Scanning Radiometer (AMSR-E) on the Aqua satellite acquires multifrequency observations twice daily (1:30 and 13:30). From these brightness temperatures come two data products relevant to land surface phenology: soil moisture and vegetation water content. Although the nominal spatial resolution of these products is coarse (25 km), the fine temporal sampling allows characterization of the diel variation in surface moisture as contained in the uppermost soil layer and bound in the vegetation canopy. The ephermal dynamics of surficial soil moisture are difficult to validate due to the scale discrepancy between the 625 sq km coverage of a single pixel and the sparse network of weather stations. In contrast, canopy dynamics are more readily validated using finer spatial resolution data products and/or ecoregionalizations. For sites in the North American Great Plains and Northern Eurasia dominated by herbaceous vegetation, I will present land surface phenologies modeled using emitted earthlight and compare them with land surface phenologies modeled using reflected sunlight. I will also explore whether some key climate modes have a significant effect on the microwave-retrieved land surface phenologies.

  1. Modelling thermocapillary migration of a microfluidic droplet on a solid surface

    Science.gov (United States)

    Liu, Haihu; Zhang, Yonghao

    2015-01-01

    A multiphase lattice Boltzmann model is developed to simulate immiscible thermocapillary flows with the presence of fluid-surface interactions. In this model, interfacial tension force and Marangoni stress are included by introducing a body force term based on the concept of continuum surface force, and phase segregation is achieved using the recolouring algorithm proposed by Latva-Kokko and Rothman. At a solid surface, fluid-surface interactions are modelled by a partial wetting boundary condition that uses a geometric formulation to specify the contact angle, and a colour-conserving boundary closure scheme to improve the numerical accuracy and suppress spurious velocities at the contact line. An additional convection-diffusion equation is solved by the passive scalar approach to obtain the temperature field, which is coupled to the hydrodynamic equations through an equation of state. This model is first validated by simulations of static contact angle and dynamic capillary intrusion process when a constant interfacial tension is considered. It is then used to simulate the thermocapillary migration of a microfluidic droplet on a horizontal solid surface subject to a uniform temperature gradient. We for the first time demonstrate numerically that the droplet motion undergoes two different states depending on the surface wettability: the droplet migrates towards the cooler regions on hydrophilic surfaces but reverses on hydrophobic surfaces. Decreasing the viscosity ratio can enhance the intensity of thermocapillary vortices, leading to an increase in migration velocity. The contact angle hysteresis, i.e., the difference between the advancing and receding contact angles, is always positive regardless of the contact angle and viscosity ratio. The contact angle hysteresis and the migration velocity both first decrease and then increase with the contact angle, and their minimum values occur at the contact angle of 90 degrees.

  2. Functional Risk Modeling for Lunar Surface Systems

    Science.gov (United States)

    Thomson, Fraser; Mathias, Donovan; Go, Susie; Nejad, Hamed

    2010-01-01

    We introduce an approach to risk modeling that we call functional modeling , which we have developed to estimate the capabilities of a lunar base. The functional model tracks the availability of functions provided by systems, in addition to the operational state of those systems constituent strings. By tracking functions, we are able to identify cases where identical functions are provided by elements (rovers, habitats, etc.) that are connected together on the lunar surface. We credit functional diversity in those cases, and in doing so compute more realistic estimates of operational mode availabilities. The functional modeling approach yields more realistic estimates of the availability of the various operational modes provided to astronauts by the ensemble of surface elements included in a lunar base architecture. By tracking functional availability the effects of diverse backup, which often exists when two or more independent elements are connected together, is properly accounted for.

  3. Modeling surface roughness scattering in metallic nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Moors, Kristof, E-mail: kristof@itf.fys.kuleuven.be [KU Leuven, Institute for Theoretical Physics, Celestijnenlaan 200D, B-3001 Leuven (Belgium); IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Sorée, Bart [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Physics Department, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium); KU Leuven, Electrical Engineering (ESAT) Department, Kasteelpark Arenberg 10, B-3001 Leuven (Belgium); Magnus, Wim [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Physics Department, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerpen (Belgium)

    2015-09-28

    Ando's model provides a rigorous quantum-mechanical framework for electron-surface roughness scattering, based on the detailed roughness structure. We apply this method to metallic nanowires and improve the model introducing surface roughness distribution functions on a finite domain with analytical expressions for the average surface roughness matrix elements. This approach is valid for any roughness size and extends beyond the commonly used Prange-Nee approximation. The resistivity scaling is obtained from the self-consistent relaxation time solution of the Boltzmann transport equation and is compared to Prange-Nee's approach and other known methods. The results show that a substantial drop in resistivity can be obtained for certain diameters by achieving a large momentum gap between Fermi level states with positive and negative momentum in the transport direction.

  4. Quantitative Modeling of Earth Surface Processes

    Science.gov (United States)

    Pelletier, Jon D.

    This textbook describes some of the most effective and straightforward quantitative techniques for modeling Earth surface processes. By emphasizing a core set of equations and solution techniques, the book presents state-of-the-art models currently employed in Earth surface process research, as well as a set of simple but practical research tools. Detailed case studies demonstrate application of the methods to a wide variety of processes including hillslope, fluvial, aeolian, glacial, tectonic, and climatic systems. Exercises at the end of each chapter begin with simple calculations and then progress to more sophisticated problems that require computer programming. All the necessary computer codes are available online at www.cambridge.org/9780521855976. Assuming some knowledge of calculus and basic programming experience, this quantitative textbook is designed for advanced geomorphology courses and as a reference book for professional researchers in Earth and planetary science looking for a quantitative approach to Earth surface processes. More details...

  5. Constraining Numerical Geodynamo Modeling with Surface Observations

    Science.gov (United States)

    Kuang, Weijia; Tangborn, Andrew

    2006-01-01

    Numerical dynamo solutions have traditionally been generated entirely by a set of self-consistent differential equations that govern the spatial-temporal variation of the magnetic field, velocity field and other fields related to dynamo processes. In particular, those solutions are obtained with parameters very different from those appropriate for the Earth s core. Geophysical application of the numerical results therefore depends on correct understanding of the differences (errors) between the model outputs and the true states (truth) in the outer core. Part of the truth can be observed at the surface in the form of poloidal magnetic field. To understand these differences, or errors, we generate new initial model state (analysis) by assimilating sequentially the model outputs with the surface geomagnetic observations using an optimal interpolation scheme. The time evolution of the core state is then controlled by our MoSST core dynamics model. The final outputs (forecasts) are then compared with the surface observations as a means to test the success of the assimilation. We use the surface geomagnetic data back to year 1900 for our studies, with 5-year forecast and 20-year analysis periods. We intend to use the result; to understand time variation of the errors with the assimilation sequences, and the impact of the assimilation on other unobservable quantities, such as the toroidal field and the fluid velocity in the core.

  6. Reflector Surface Modelling : A European Collaboration

    NARCIS (Netherlands)

    Albani, M; Balling, P.; Ettorre, M.; Gerini, G.; Maci, S.; Pontoppidan, K.; Sipus, Z.; Sjöberg, D.; Vecchi, G.; Vipiana, F.

    2007-01-01

    The topic of this paper is the work carried out in Work Package 2.3-2 of the EU network ACE. This work package is concerned with the modelling of the surfaces of modern reflector antennas. In particular the problems associated with homogenisation of periodic structures are described together with an

  7. Global modelling of Cryptosporidium in surface water

    Science.gov (United States)

    Vermeulen, Lucie; Hofstra, Nynke

    2016-04-01

    Introduction Waterborne pathogens that cause diarrhoea, such as Cryptosporidium, pose a health risk all over the world. In many regions quantitative information on pathogens in surface water is unavailable. Our main objective is to model Cryptosporidium concentrations in surface waters worldwide. We present the GloWPa-Crypto model and use the model in a scenario analysis. A first exploration of global Cryptosporidium emissions to surface waters has been published by Hofstra et al. (2013). Further work has focused on modelling emissions of Cryptosporidium and Rotavirus to surface waters from human sources (Vermeulen et al 2015, Kiulia et al 2015). A global waterborne pathogen model can provide valuable insights by (1) providing quantitative information on pathogen levels in data-sparse regions, (2) identifying pathogen hotspots, (3) enabling future projections under global change scenarios and (4) supporting decision making. Material and Methods GloWPa-Crypto runs on a monthly time step and represents conditions for approximately the year 2010. The spatial resolution is a 0.5 x 0.5 degree latitude x longitude grid for the world. We use livestock maps (http://livestock.geo-wiki.org/) combined with literature estimates to calculate spatially explicit livestock Cryptosporidium emissions. For human Cryptosporidium emissions, we use UN population estimates, the WHO/UNICEF JMP sanitation country data and literature estimates of wastewater treatment. We combine our emissions model with a river routing model and data from the VIC hydrological model (http://vic.readthedocs.org/en/master/) to calculate concentrations in surface water. Cryptosporidium survival during transport depends on UV radiation and water temperature. We explore pathogen emissions and concentrations in 2050 with the new Shared Socio-economic Pathways (SSPs) 1 and 3. These scenarios describe plausible future trends in demographics, economic development and the degree of global integration. Results and

  8. Hydrophilic nanoporous polystyrenes and 1,2-polybutadienes

    DEFF Research Database (Denmark)

    Guo, Fengxiao; Jankova Atanasova, Katja; Vigild, Martin Etchells;

    2008-01-01

    Nanoporous polymers from ordered block copolymers having hydrophilic cavity surfaces were successfully prepared by two methodologies: ' 1. Nanoporous polystyrenes fromPtBA-b-PS diblock or PDMS-b-PtBA-b-PS triblock copolymer precursors by atom transfer radical polymerization (ATRP), or combination...... different pathways for the conversion of the double bonds of 1,2-PB to bromoisobutyrate by using one to three steps chemical modification. Grafting polyacrylate layers of PPEGMA, PHEMA etc. onto themon...

  9. Vision models for 3D surfaces

    Science.gov (United States)

    Mitra, Sunanda

    1992-11-01

    Different approaches to computational stereo to represent human stereo vision have been developed over the past two decades. The Marr-Poggio theory of human stereo vision is probably the most widely accepted model of the human stereo vision. However, recently developed motion stereo models which use a sequence of images taken by either a moving camera or a moving object provide an alternative method of achieving multi-resolution matching without the use of Laplacian of Gaussian operators. While using image sequences, the baseline between two camera positions for a image pair is changed for the subsequent image pair so as to achieve different resolution for each image pair. Having different baselines also avoids the inherent occlusion problem in stereo vision models. The advantage of using multi-resolution images acquired by camera positioned at different baselines over those acquired by LOG operators is that one does not have to encounter spurious edges often created by zero-crossings in the LOG operated images. Therefore in designing a computer vision system, a motion stereo model is more appropriate than a stereo vision model. However, in some applications where only a stereo pair of images are available, recovery of 3D surfaces of natural scenes are possible in a computationally efficient manner by using cepstrum matching and regularization techniques. Section 2 of this paper describes a motion stereo model using multi-scale cepstrum matching for the detection of disparity between image pairs in a sequence of images and subsequent recovery of 3D surfaces from depth-map obtained by a non convergent triangulation technique. Section 3 presents a 3D surface recovery technique from a stereo pair using cepstrum matching for disparity detection and cubic B-splines for surface smoothing. Section 4 contains the results of 3D surface recovery using both of the techniques mentioned above. Section 5 discusses the merit of 2D cepstrum matching and cubic B

  10. Enhanced catalytic activity and inhibited biofouling of cathode in microbial fuel cells through controlling hydrophilic property

    Science.gov (United States)

    Li, Da; Liu, Jia; Wang, Haiman; Qu, Youpeng; Zhang, Jie; Feng, Yujie

    2016-11-01

    The hydrophilicity of activated carbon cathode directly determines the distribution of three-phase interfaces where oxygen reduction occurs. In this study, activated carbon cathodes are fabricated by using hydrophobic polytetrafluoroethylene (PTFE) and amphiphilic LA132 at various weight ratio to investigate the effect of hydrophilic property on cathode performance. Contact angle tests confirm the positive impact of LA132 content on hydrophilicity. Cathode with 67 wt% LA132 content shows the highest electrochemical activity as exchange current density increases by 71% and charge transfer resistance declines by 44.6% compared to that of PTFE cathode, probably due to the extended reaction interfaces by optimal hydrophilicity of cathode so that oxygen reduction is facilitated. As a result, the highest power density of 1171 ± 71 mW m-2 is obtained which is 14% higher than PTFE cathode. In addition to the hydrophilicity, this cathode had more negative charged surface of catalyst layer, therefore the protein content of cathodic biofilm decreased by 47.5%, indicating the effective bacterial inhibition when 67 wt% LA132 is used. This study shows that the catalytic activity of cathode is improved by controlling proper hydrophilicity of cathode, and that biofilm can be reduced by increasing hydrophilicity and lowering the surface potential.

  11. Work Functions for Models of Scandate Surfaces

    Science.gov (United States)

    Mueller, Wolfgang

    1997-01-01

    The electronic structure, surface dipole properties, and work functions of scandate surfaces have been investigated using the fully relativistic scattered-wave cluster approach. Three different types of model surfaces are considered: (1) a monolayer of Ba-Sc-O on W(100), (2) Ba or BaO adsorbed on Sc2O3 + W, and (3) BaO on SC2O3 + WO3. Changes in the work function due to Ba or BaO adsorption on the different surfaces are calculated by employing the depolarization model of interacting surface dipoles. The largest work function change and the lowest work function of 1.54 eV are obtained for Ba adsorbed on the Sc-O monolayer on W(100). The adsorption of Ba on Sc2O3 + W does not lead to a low work function, but the adsorption of BaO results in a work function of about 1.6-1.9 eV. BaO adsorbed on Sc2O3 + WO3, or scandium tungstates, may also lead to low work functions.

  12. Hydrogen scattering from a cesiated surface model

    Science.gov (United States)

    Rutigliano, Maria; Palma, Amedeo; Sanna, Nico

    2017-10-01

    A cesiated surface model was considered to study the dynamics of hydrogen atom scattering using a semiclassical collisional method. Using dipole correction method, the work function of the considered surface, is calculated to be 1.81 eV (± 0.02) eV. The Potential Energy Surface for the interaction of H atoms with the surface was determined via first principle electronic structure calculations including the interaction with both Cs and Mo atoms of the surface. We found the scattered H atoms to have a negative partial charge of nearly 0.4 with the backscattered flux arising mainly from H atoms impinging directly (or very close) to Cs atoms on the surface. On the contrary, H atoms impinging in the voids between the Cs atoms propagate through the first Cs layer and remain adsorbed. The propagation occurs mainly in the vertical direction. The scattering probability after a very quick increase remains almost constant around an average value of 0.35.

  13. Grain Surface Models and Data for Astrochemistry

    Science.gov (United States)

    Cuppen, H. M.; Walsh, C.; Lamberts, T.; Semenov, D.; Garrod, R. T.; Penteado, E. M.; Ioppolo, S.

    2017-01-01

    The cross-disciplinary field of astrochemistry exists to understand the formation, destruction, and survival of molecules in astrophysical environments. Molecules in space are synthesized via a large variety of gas-phase reactions, and reactions on dust-grain surfaces, where the surface acts as a catalyst. A broad consensus has been reached in the astrochemistry community on how to suitably treat gas-phase processes in models, and also on how to present the necessary reaction data in databases; however, no such consensus has yet been reached for grain-surface processes. A team of {˜}25 experts covering observational, laboratory and theoretical (astro)chemistry met in summer of 2014 at the Lorentz Center in Leiden with the aim to provide solutions for this problem and to review the current state-of-the-art of grain surface models, both in terms of technical implementation into models as well as the most up-to-date information available from experiments and chemical computations. This review builds on the results of this workshop and gives an outlook for future directions.

  14. Surface Barrier Models of ZnO

    Institute of Scientific and Technical Information of China (English)

    MA Yong; WANG Wan-lu; LIAO Ke-jun; KONG Chun-yang

    2004-01-01

    For a low surface barrier, the energy band, barrier height and width of the space charge region at the surface of relatively large grains of ZnO are presented analytically on condition that the electron distribution obeys the Boltzmann statistics. It is shown that the temperature in the space charge distribution factor has an important effect on the energy band, barrier height and width of the space charge region. The depletion approximation is a model in which the temperature in the space charge distribution factor is zero. Our results are better than the depletion approximation.

  15. Integration of Heterogenous Digital Surface Models

    Science.gov (United States)

    Boesch, R.; Ginzler, C.

    2011-08-01

    The application of extended digital surface models often reveals, that despite an acceptable global accuracy for a given dataset, the local accuracy of the model can vary in a wide range. For high resolution applications which cover the spatial extent of a whole country, this can be a major drawback. Within the Swiss National Forest Inventory (NFI), two digital surface models are available, one derived from LiDAR point data and the other from aerial images. Automatic photogrammetric image matching with ADS80 aerial infrared images with 25cm and 50cm resolution is used to generate a surface model (ADS-DSM) with 1m resolution covering whole switzerland (approx. 41000 km2). The spatially corresponding LiDAR dataset has a global point density of 0.5 points per m2 and is mainly used in applications as interpolated grid with 2m resolution (LiDAR-DSM). Although both surface models seem to offer a comparable accuracy from a global view, local analysis shows significant differences. Both datasets have been acquired over several years. Concerning LiDAR-DSM, different flight patterns and inconsistent quality control result in a significantly varying point density. The image acquisition of the ADS-DSM is also stretched over several years and the model generation is hampered by clouds, varying illumination and shadow effects. Nevertheless many classification and feature extraction applications requiring high resolution data depend on the local accuracy of the used surface model, therefore precise knowledge of the local data quality is essential. The commercial photogrammetric software NGATE (part of SOCET SET) generates the image based surface model (ADS-DSM) and delivers also a map with figures of merit (FOM) of the matching process for each calculated height pixel. The FOM-map contains matching codes like high slope, excessive shift or low correlation. For the generation of the LiDAR-DSM only first- and last-pulse data was available. Therefore only the point distribution can

  16. A theoretical model of metal surface reactions

    Energy Technology Data Exchange (ETDEWEB)

    Shustorovich, E. (Eastman Kodak Co., Rochester, NY); Baetzold, R.C.; Muetterties, E.L.

    1983-03-31

    Metal surface reactions are modeled with a novel theoretical construct in which periodic trends can be scrutinized. The theoretical model is succinctly presented and a conspectus of periodic trends, based on the model, is explored. Periodic trends are discussed in the contexts of chemisorption bond energies, electron transfer between metal surface and adsorbate, stereochemical features of chemisorption states for closed-shell diatomic and linear X-CN or X-NC molecules, and hydrocarbon reactions. Hydrocarbon C-H bond-breaking processes are analyzed in terms of d-level occupancy, electron transfer, and stereochemistry of intermediates. Conceptually and computationally, the metal surface is characterized as a good electron donor: antibonding molecular orbitals of the adsorbate species appear to be significant contributors to the chemisorption bond and also play a decisive role in bond-breaking processes. No aspect of the model projections is inconsistent with the experimental data although the electronic characterization of some chemisorption states are counter to commonly held perceptions.

  17. Uncertainty in surface water flood risk modelling

    Science.gov (United States)

    Butler, J. B.; Martin, D. N.; Roberts, E.; Domuah, R.

    2009-04-01

    Two thirds of the flooding that occurred in the UK during summer 2007 was as a result of surface water (otherwise known as ‘pluvial') rather than river or coastal flooding. In response, the Environment Agency and Interim Pitt Reviews have highlighted the need for surface water risk mapping and warning tools to identify, and prepare for, flooding induced by heavy rainfall events. This need is compounded by the likely increase in rainfall intensities due to climate change. The Association of British Insurers has called for the Environment Agency to commission nationwide flood risk maps showing the relative risk of flooding from all sources. At the wider European scale, the recently-published EC Directive on the assessment and management of flood risks will require Member States to evaluate, map and model flood risk from a variety of sources. As such, there is now a clear and immediate requirement for the development of techniques for assessing and managing surface water flood risk across large areas. This paper describes an approach for integrating rainfall, drainage network and high-resolution topographic data using Flowroute™, a high-resolution flood mapping and modelling platform, to produce deterministic surface water flood risk maps. Information is provided from UK case studies to enable assessment and validation of modelled results using historical flood information and insurance claims data. Flowroute was co-developed with flood scientists at Cambridge University specifically to simulate river dynamics and floodplain inundation in complex, congested urban areas in a highly computationally efficient manner. It utilises high-resolution topographic information to route flows around individual buildings so as to enable the prediction of flood depths, extents, durations and velocities. As such, the model forms an ideal platform for the development of surface water flood risk modelling and mapping capabilities. The 2-dimensional component of Flowroute employs

  18. Improving land surface models with FLUXNET data

    Directory of Open Access Journals (Sweden)

    Y. -P. Wang

    2009-07-01

    Full Text Available There is a growing consensus that land surface models (LSMs that simulate terrestrial biosphere exchanges of matter and energy must be better constrained with data to quantify and address their uncertainties. FLUXNET, an international network of sites that measure the land surface exchanges of carbon, water and energy using the eddy covariance technique, is a prime source of data for model improvement. Here we outline a multi-stage process for "fusing" (i.e. linking LSMs with FLUXNET data to generate better models with quantifiable uncertainty. First, we describe FLUXNET data availability, and its random and systematic biases. We then introduce methods for assessing LSM model runs against FLUXNET observations in temporal and spatial domains. These assessments are a prelude to more formal model-data fusion (MDF. MDF links model to data, based on error weightings. In theory, MDF produces optimal analyses of the modelled system, but there are practical problems. We first discuss how to set model errors and initial conditions. In both cases incorrect assumptions will affect the outcome of the MDF. We then review the problem of equifinality, whereby multiple combinations of parameters can produce similar model output. Fusing multiple independent and orthogonal data provides a means to limit equifinality. We then show how parameter probability density functions (PDFs from MDF can be used to interpret model validity, and to propagate errors into model outputs. Posterior parameter distributions are a useful way to assess the success of MDF, combined with a determination of whether model residuals are Gaussian. If the MDF scheme provides evidence for temporal variation in parameters, then that is indicative of a critical missing dynamic process. A comparison of parameter PDFs generated with the same model from multiple FLUXNET sites can provide insights into the concept and validity of plant functional types (PFT – we would expect similar parameter

  19. Improving land surface models with FLUXNET data

    Directory of Open Access Journals (Sweden)

    M. Williams

    2009-03-01

    Full Text Available There is a growing consensus that land surface models (LSMs that simulate terrestrial biosphere exchanges of matter and energy must be better constrained with data to quantify and address their uncertainties. FLUXNET, an international network of sites that measure the land surface exchanges of carbon, water and energy using the eddy covariance technique, is a prime source of data for model improvement. Here we outline a multi-stage process for fusing LSMs with FLUXNET data to generate better models with quantifiable uncertainty. First, we describe FLUXNET data availability, and its random and systematic biases. We then introduce methods for assessing LSM model runs against FLUXNET observations in temporal and spatial domains. These assessments are a prelude to more formal model-data fusion (MDF. MDF links model to data, based on error weightings. In theory, MDF produces optimal analyses of the modelled system, but there are practical problems. We first discuss how to set model errors and initial conditions. In both cases incorrect assumptions will affect the outcome of the MDF. We then review the problem of equifinality, whereby multiple combinations of parameters can produce similar model output. Fusing multiple independent data provides a means to limit equifinality. We then show how parameter probability density functions (PDFs from MDF can be used to interpret model process validity, and to propagate errors into model outputs. Posterior parameter distributions are a useful way to assess the success of MDF, combined with a determination of whether model residuals are Gaussian. If the MDF scheme provides evidence for temporal variation in parameters, then that is indicative of a critical missing dynamic process. A comparison of parameter PDFs generated with the same model from multiple FLUXNET sites can provide insights into the concept and validity of plant functional types (PFT – we would expect similar parameter estimates among sites

  20. Modeling heterogeneous chemical processes on aerosol surface

    Institute of Scientific and Technical Information of China (English)

    Junjun Deng; Tijian Wang; Li Liu; Fei Jiang

    2010-01-01

    To explore the possible impact of heterogeneous chemical processes on atmospheric trace components,a coupled box model including gas-phase chemical processes,aerosol thermodynamic equilibrium processes,and heterogeneous chemical processes on the surface of dust,black carbon(BC)and sea salt is set up to simulate the effects of heterogeneous chemistry on the aerosol surface,and analyze the primary factors affecting the heterogeneous processes.Results indicate that heterogeneous chemical processes on the aerosol surface in the atmosphere will affect the concentrations of trace gases such as H2O2,HO2,O3,NO2,NO3,HNO3 and SO2,and aerosols such as SO42-,NO3-and NH4+.Sensitivity tests suggest that the magnitude of the impact of heterogeneous processes strongly depends on aerosol concentration and the surface uptake coefficients used in the box model.However,the impact of temperature on heterogeneous chemical processes is considerably less.The"renoxification"of HNO3 will affect the components of the troposphere such as nitrogen oxide and ozone.

  1. 亲水改性碳钢极板用于PM2.5脱除%PM2.5 collection using surface-modified hydrophilic carbon steel collector

    Institute of Scientific and Technical Information of China (English)

    徐纯燕; 常景彩; 王翔; 张静; 崔琳; 张波; 马春元

    2016-01-01

    Fine particles with aerodynamic diameters of<2.5μm (PM2.5) are significant pollution sources. Dust emission is restricted to less than 10 mg·m−3 under 6% oxygen in eastern China and wet electrostatic precipitators (ESPs) are encouraged for efficient removal of various fine particles in aerosol, especially in coal-fired power plant where strict air pollutant emission standards drive wide use of wet ESP as terminal control equipment. Previous studies showed wetting properties of a hydrophilically modified rigid collector and this study focused on fine particle collection performance of the modified collector at pilot scale. The characteristics of PM2.5 collection, mechanism of uniform water film and effect of main operation parameters on enhancement of particle collection efficiency were investigated. The results showed that the surface fiber layer of the modified rigid collectors reduced flue gas recoiling and particle electro-transportation resistance. A uniform and stable water film was maintained on surfaces of the modified rigid collectors at low washing water flowrate, which inhibited back corona occurrence and a secondary entrainment of dust as well as increased discharge current and flue gas humidity by evaporation of water film. The increase of particle charge number and electro-transportation speed enhanced the particle collection efficiency. With the increase of flue gas temperature, both discharge current and thermophoresis force gradually increased which could improve the particle collection efficiency. However, the increase of gas viscosity reduced the particles collection efficiency. The extension of residence time and the increase of applied voltage improved particle collection, whereas the inlet concentration of particles and the flushing water flowrate had little influence on particle collection. The wet ESPs of modified rigid collectors exhibited reduction of circulating water consumption per square meter by 86 percent and significant increase

  2. Modeling of ESD events from polymeric surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pfeifer, Kent Bryant

    2014-03-01

    Transient electrostatic discharge (ESD) events are studied to assemble a predictive model of discharge from polymer surfaces. An analog circuit simulation is produced and its response is compared to various literature sources to explore its capabilities and limitations. Results suggest that polymer ESD events can be predicted to within an order of magnitude. These results compare well to empirical findings from other sources having similar reproducibility.

  3. Shallow Water Propagation and Surface Reverberation Modeling

    Science.gov (United States)

    2012-09-30

    compare the results with experiment. This work will be used to help interpret field data of bistatic scattering from sea ice cover and calibrate...approximate analytical and numerical acoustic models used to compute bistatic scattering. The clouds of bubbles entrained at the sea surface by breaking...ABSTRACT SAR 18. NUMBER OF PAGES 7 19a. NAME OF RESPONSIBLE PERSON a. REPORT unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified

  4. Statistical Seasonal Sea Surface based Prediction Model

    Science.gov (United States)

    Suarez, Roberto; Rodriguez-Fonseca, Belen; Diouf, Ibrahima

    2014-05-01

    The interannual variability of the sea surface temperature (SST) plays a key role in the strongly seasonal rainfall regime on the West African region. The predictability of the seasonal cycle of rainfall is a field widely discussed by the scientific community, with results that fail to be satisfactory due to the difficulty of dynamical models to reproduce the behavior of the Inter Tropical Convergence Zone (ITCZ). To tackle this problem, a statistical model based on oceanic predictors has been developed at the Universidad Complutense of Madrid (UCM) with the aim to complement and enhance the predictability of the West African Monsoon (WAM) as an alternative to the coupled models. The model, called S4CAST (SST-based Statistical Seasonal Forecast) is based on discriminant analysis techniques, specifically the Maximum Covariance Analysis (MCA) and Canonical Correlation Analysis (CCA). Beyond the application of the model to the prediciton of rainfall in West Africa, its use extends to a range of different oceanic, atmospheric and helth related parameters influenced by the temperature of the sea surface as a defining factor of variability.

  5. Improvements on Mean Free Wave Surface Modeling

    Institute of Scientific and Technical Information of China (English)

    董国海; 滕斌; 程亮

    2002-01-01

    Some new results of the modeling of mean free surface of waves or wave set-up are presented. The stream function wave theory is applied to incident short waves. The limiting wave steepness is adopted as the wave breaker index in the calculation of wave breaking dissipation. The model is based on Roelvink (1993), but the numerical techniques used in the solution are based on the Weighted-Average Flux (WAF) method (Watson et al., 1992), with Time-Operator-Splitting (TOS) used for the treatment of the source terms. This method allows a small number of computational points to be used, and is particularly efficient in modeling wave set-up. The short wave (or incident primary wave) energy equation issolved by use of a traditional Lax-Wendroff technique. The present model is found to be satisfactory compared with the measurements conducted by Stive (1983).

  6. Pretreatment and Membrane Hydrophilic Modification to Reduce Membrane Fouling

    Directory of Open Access Journals (Sweden)

    Huaqiang Chu

    2013-09-01

    Full Text Available The application of low pressure membranes (microfiltration/ultrafiltration has undergone accelerated development for drinking water production. However, the major obstacle encountered in its popularization is membrane fouling caused by natural organic matter (NOM. This paper firstly summarizes the two factors causing the organic membrane fouling, including molecular weight (MW and hydrophilicity/hydrophobicity of NOM, and then presents a brief introduction of the methods which can prevent membrane fouling such as pretreatment of the feed water (e.g., coagulation, adsorption, and pre-oxidation and membrane hydrophilic modification (e.g., plasma modification, irradiation grafting modification, surface coating modification, blend modification, etc.. Perspectives of further research are also discussed.

  7. Facile transformation of superhydrophobicity to hydrophilicity by silica/poly(ɛ-caprolactone) composite film

    Science.gov (United States)

    Gao, Zhengxin; Zhai, Xianglin; Wang, Chengyu

    2015-12-01

    A smart surface with thermo-responsive wettability was fabricated on the cross section of wood with simple bench chemistry. The surface showed fast response between superhydrophobic and hydrophilic under different temperatures. The reversible wettability from superhydrophobicity to hydrophilicity can be easily achieved by adjusting the temperature between 25 and 60 °C. This reversible wettability is resulted from the synergistic effect of the crystallinity transition of the polymer coated on the surface and the optimized roughness controlled by the silica particles with different sizes. Furthermore, the modified wood surface showed an excellent chemical stability to corrosive liquids under ambient conditions.

  8. Water vapor adsorption in activated carbon modified with hydrophilic organic salts

    Institute of Scientific and Technical Information of China (English)

    姚小龙; 李立清; 李海龙; 池东

    2015-01-01

    Five different kinds of hydrophilic organic salts were used to modify commercial activated carbon in order to prepare hydrophilic carbon materials. Properties of the samples were analyzed by surface area analyzer and SEM-EDX. The hydrophilic organic salts with different properties were introduced into activated carbon and significantly affected the properties of the samples. During adsorption experiments, the water vapor adsorption amount in modified samples increases by 0.57−17.12 times in temperature range from 303 to 323 K and at relative pressure below 0.50. Water molecules combined with surface hydrophilic groups through H-bonding exhibit good thermo stability. The effects of temperature, oxygen content and properties of the hydrophilic organic salts on water vapor adsorption were studied. It is indicated that water vapor adsorption in modified samples is mainly affected by the surface oxygen content. The carboxylate radicals in the hydrophilic organic salts greatly affect the micropore structure of the modified samples, while the metal ions in them exhibit limited influence. Different adsorption capacity of modified samples can be explained with the electronegativity of elements presented by Pauling.

  9. Facile transformation of superhydrophobicity to hydrophilicity by silica/poly(ε-caprolactone) composite film

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Zhengxin [Key Laboratory of Bio-Based Material Science and Technology, Ministry of Education, Northeast Forestry University, Harbin 150040 (China); Zhai, Xianglin [Department of Chemistry, Louisiana State University, Baton Rouge, LA 70803 (United States); Wang, Chengyu, E-mail: wangcy@nefu.edu.cn [Key Laboratory of Bio-Based Material Science and Technology, Ministry of Education, Northeast Forestry University, Harbin 150040 (China)

    2015-12-30

    Graphical abstract: - Highlights: • The superhydrophobic wood was prepared by an effective method with simple immersion and pipetting steps. • The superhydrophobic wood shows fast thermo-response wettability transition between superhydrophobicity and hydrophilicity. • The modified wood surface is stable to the corrosive liquids. - Abstract: A smart surface with thermo-responsive wettability was fabricated on the cross section of wood with simple bench chemistry. The surface showed fast response between superhydrophobic and hydrophilic under different temperatures. The reversible wettability from superhydrophobicity to hydrophilicity can be easily achieved by adjusting the temperature between 25 and 60 °C. This reversible wettability is resulted from the synergistic effect of the crystallinity transition of the polymer coated on the surface and the optimized roughness controlled by the silica particles with different sizes. Furthermore, the modified wood surface showed an excellent chemical stability to corrosive liquids under ambient conditions.

  10. Sub-discretized surface model with application to contact mechanics in multi-body simulation

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, S; Williams, J

    2008-02-28

    The mechanics of contact between rough and imperfectly spherical adhesive powder grains are often complicated by a variety of factors, including several which vary over sub-grain length scales. These include several traction factors that vary spatially over the surface of the individual grains, including high energy electron and acceptor sites (electrostatic), hydrophobic and hydrophilic sites (electrostatic and capillary), surface energy (general adhesion), geometry (van der Waals and mechanical), and elasto-plastic deformation (mechanical). For mechanical deformation and reaction, coupled motions, such as twisting with bending and sliding, as well as surface roughness add an asymmetry to the contact force which invalidates assumptions for popular models of contact, such as the Hertzian and its derivatives, for the non-adhesive case, and the JKR and DMT models for adhesive contacts. Though several contact laws have been offered to ameliorate these drawbacks, they are often constrained to particular loading paths (most often normal loading) and are relatively complicated for computational implementation. This paper offers a simple and general computational method for augmenting contact law predictions in multi-body simulations through characterization of the contact surfaces using a hierarchically-defined surface sub-discretization. For the case of adhesive contact between powder grains in low stress regimes, this technique can allow a variety of existing contact laws to be resolved across scales, allowing for moments and torques about the contact area as well as normal and tangential tractions to be resolved. This is especially useful for multi-body simulation applications where the modeler desires statistical distributions and calibration for parameters in contact laws commonly used for resolving near-surface contact mechanics. The approach is verified against analytical results for the case of rough, elastic spheres.

  11. An Efficient Hydrodynamic Model for Surface Waves

    Institute of Scientific and Technical Information of China (English)

    WANG Kun; JIN Sheng; LU Gang

    2009-01-01

    In the present study,a semi-implicit finite difference model for non-bydrostatic,free-surface flows is analyzed and discussed.The governing equations are the three-dimensional free-surface Reynolds-averaged Navier-Stokes equations defined on a general,irregular domain of arbitrary scale.At outflow,a combination of a sponge layer technique and a radiation boundary condition is applied to minimize wave reflection.The equations are solved with the fractional step method where the hydrostatic pressure component is determined first,while the non-hydrostatic component of the pressure is computed from the pressure Poisson equation in which the coefficient matrix is positive definite and symmetric.The advectiou and horizontal viscosity terms are discretized by use of a semi-Lagrangian approach.The resulting model is computationally efficient and unrestricted to the CFL condition.The developed model is verified against analytical solutions and experimental data,with excellent agreement.

  12. A new experimental design method to optimize formulations focusing on a lubricant for hydrophilic matrix tablets.

    Science.gov (United States)

    Choi, Du Hyung; Shin, Sangmun; Khoa Viet Truong, Nguyen; Jeong, Seong Hoon

    2012-09-01

    A robust experimental design method was developed with the well-established response surface methodology and time series modeling to facilitate the formulation development process with magnesium stearate incorporated into hydrophilic matrix tablets. Two directional analyses and a time-oriented model were utilized to optimize the experimental responses. Evaluations of tablet gelation and drug release were conducted with two factors x₁ and x₂: one was a formulation factor (the amount of magnesium stearate) and the other was a processing factor (mixing time), respectively. Moreover, different batch sizes (100 and 500 tablet batches) were also evaluated to investigate an effect of batch size. The selected input control factors were arranged in a mixture simplex lattice design with 13 experimental runs. The obtained optimal settings of magnesium stearate for gelation were 0.46 g, 2.76 min (mixing time) for a 100 tablet batch and 1.54 g, 6.51 min for a 500 tablet batch. The optimal settings for drug release were 0.33 g, 7.99 min for a 100 tablet batch and 1.54 g, 6.51 min for a 500 tablet batch. The exact ratio and mixing time of magnesium stearate could be formulated according to the resulting hydrophilic matrix tablet properties. The newly designed experimental method provided very useful information for characterizing significant factors and hence to obtain optimum formulations allowing for a systematic and reliable experimental design method.

  13. Near-infrared labeled, ovalbumin loaded polymeric nanoparticles based on a hydrophilic polyester as model vaccine: In vivo tracking and evaluation of antigen-specific CD8(+) T cell immune response.

    Science.gov (United States)

    Rahimian, Sima; Kleinovink, Jan Willem; Fransen, Marieke F; Mezzanotte, Laura; Gold, Henrik; Wisse, Patrick; Overkleeft, Hermen; Amidi, Maryam; Jiskoot, Wim; Löwik, Clemens W; Ossendorp, Ferry; Hennink, Wim E

    2015-01-01

    Particulate antigen delivery systems aimed at the induction of antigen-specific T cells form a promising approach in immunotherapy to replace pharmacokinetically unfavorable soluble antigen formulations. In this study, we developed a delivery system using the model protein antigen ovalbumin (OVA) encapsulated in nanoparticles based on the hydrophilic polyester poly(lactide-co-hydroxymethylglycolic acid) (pLHMGA). Spherical nanoparticles with size 300-400 nm were prepared and characterized and showed a strong ability to deliver antigen to dendritic cells for cross-presentation to antigen-specific T cells in vitro. Using near-infrared (NIR) fluorescent dyes covalently linked to both the nanoparticle and the encapsulated OVA antigen, we tracked the fate of this formulation in mice. We observed that the antigen and the nanoparticles are efficiently co-transported from the injection site to the draining lymph nodes, in a more gradual and durable manner than soluble OVA protein. OVA-loaded pLHMGA nanoparticles efficiently induced antigen cross-presentation to OVA-specific CD8+ T cells in the lymph nodes, superior to soluble OVA vaccination. Together, these data show the potential of pLHMGA nanoparticles as attractive antigen delivery vehicles.

  14. Hydrophilic Mineral Coating of Membrane Substrate for Reducing Internal Concentration Polarization (ICP) in Forward Osmosis

    Science.gov (United States)

    Liu, Qing; Li, Jingguo; Zhou, Zhengzhong; Xie, Jianping; Lee, Jim Yang

    2016-01-01

    Internal concentration polarization (ICP) is a major issue in forward osmosis (FO) as it can significantly reduce the water flux in FO operations. It is known that a hydrophilic substrate and a smaller membrane structure parameter (S) are effective against ICP. This paper reports the development of a thin film composite (TFC) FO membrane with a hydrophilic mineral (CaCO3)-coated polyethersulfone (PES)-based substrate. The CaCO3 coating was applied continuously and uniformly on the membrane pore surfaces throughout the TFC substrate. Due to the intrinsic hydrophilicity of the CaCO3 coating, the substrate hydrophilicity was significantly increased and the membrane S parameter was reduced to as low as the current best of cellulose-based membranes but without the mechanical fragility of the latter. As a result, the ICP of the TFC-FO membrane could be significantly reduced to yield a remarkable increase in water flux without the loss of membrane selectivity.

  15. Revising Hydrology of a Land Surface Model

    Science.gov (United States)

    Le Vine, Nataliya; Butler, Adrian; McIntyre, Neil; Jackson, Christopher

    2015-04-01

    Land Surface Models (LSMs) are key elements in guiding adaptation to the changing water cycle and the starting points to develop a global hyper-resolution model of the terrestrial water, energy and biogeochemical cycles. However, before this potential is realised, there are some fundamental limitations of LSMs related to how meaningfully hydrological fluxes and stores are represented. An important limitation is the simplistic or non-existent representation of the deep subsurface in LSMs; and another is the lack of connection of LSM parameterisations to relevant hydrological information. In this context, the paper uses a case study of the JULES (Joint UK Land Environmental Simulator) LSM applied to the Kennet region in Southern England. The paper explores the assumptions behind JULES hydrology, adapts the model structure and optimises the coupling with the ZOOMQ3D regional groundwater model. The analysis illustrates how three types of information can be used to improve the model's hydrology: a) observations, b) regionalized information, and c) information from an independent physics-based model. It is found that: 1) coupling to the groundwater model allows realistic simulation of streamflows; 2) a simple dynamic lower boundary improves upon JULES' stationary unit gradient condition; 3) a 1D vertical flow in the unsaturated zone is sufficient; however there is benefit in introducing a simple dual soil moisture retention curve; 4) regionalized information can be used to describe soil spatial heterogeneity. It is concluded that relatively simple refinements to the hydrology of JULES and its parameterisation method can provide a substantial step forward in realising its potential as a high-resolution multi-purpose model.

  16. Switchable hydrophobic-hydrophilic layer obtained onto porous alumina by plasma-enhanced fluorination

    Institute of Scientific and Technical Information of China (English)

    A.TRESSAUD; C.LABRUG(E)RE; E.DURAND; C.BRIGOULEIX; H.ANDRIESSEN

    2009-01-01

    Conventional lithographic printing processes using porous alumina for offset applications generally use "wet" routes. Recently "dry" processes have been developed which are based on a heat-induced hydrophilic/oleophilic conversion of one or more layers of the coating so that a stronger affinity to-wards ink or water fountain is created at the exposed areas with respect to the surface of the unex-posed coating. Treatments involving rf plasma-enhanced fluorination (PEF) constitute exceptional tools for modifying the surface properties of materials. Many advantages of these techniques can be indeed outlined, when compared to more conventional methods: room-temperature reactions, chemical modi-fications limited to surface only without changing the bulk properties, possible non-equilibrium reac-tions. The influence of PEF treatments on porous alumina layer used in printing plates has been tested with various fluorinated gases (CF4, C3F8and C4F8) and characterized by XPS. The hydrophobic prop-erties of the fluorinated layer have been deduced from contact angle measurements. Using C4Fs rf-PEF treatment, the outmost surface of the hydrophilic alumina substrate used for lithographic printing is hydrophobized, or in other words, the hydrophilic substrate is converted into a support with hydro-phobic properties. Once being hydrophobized, the surface layer may be rendered hydrophilic using a heat pulse, thus giving rise to switchable hydrophobic-hydrophilic properties of the material.

  17. Switchable hydrophobic-hydrophilic layer obtained onto porous alumina by plasma-enhanced fluorination

    Institute of Scientific and Technical Information of China (English)

    A.; TRESSAUD; C.; LABRUGèRE; E.; DURAND; C.; BRIGOULEIX; H.; ANDRIESSEN

    2009-01-01

    Conventional lithographic printing processes using porous alumina for offset applications generally use "wet" routes. Recently "dry" processes have been developed which are based on a heat-induced hydrophilic/oleophilic conversion of one or more layers of the coating so that a stronger affinity to-wards ink or water fountain is created at the exposed areas with respect to the surface of the unex-posed coating. Treatments involving rf plasma-enhanced fluorination (PEF) constitute exceptional tools for modifying the surface properties of materials. Many advantages of these techniques can be indeed outlined, when compared to more conventional methods: room-temperature reactions, chemical modi-fications limited to surface only without changing the bulk properties, possible non-equilibrium reac-tions. The influence of PEF treatments on porous alumina layer used in printing plates has been tested with various fluorinated gases (CF4, C3F8 and C4F8) and characterized by XPS. The hydrophobic prop-erties of the fluorinated layer have been deduced from contact angle measurements. Using C4F8 rf-PEF treatment, the outmost surface of the hydrophilic alumina substrate used for lithographic printing is hydrophobized, or in other words, the hydrophilic substrate is converted into a support with hydro-phobic properties. Once being hydrophobized, the surface layer may be rendered hydrophilic using a heat pulse, thus giving rise to switchable hydrophobic-hydrophilic properties of the material.

  18. Can the hydrophilicity of functional monomers affect chemical interaction?

    Science.gov (United States)

    Feitosa, V P; Ogliari, F A; Van Meerbeek, B; Watson, T F; Yoshihara, K; Ogliari, A O; Sinhoreti, M A; Correr, A B; Cama, G; Sauro, S

    2014-02-01

    The number of carbon atoms and/or ester/polyether groups in spacer chains may influence the interaction of functional monomers with calcium and dentin. The present study assessed the chemical interaction and bond strength of 5 standard-synthesized phosphoric-acid ester functional monomers with different spacer chain characteristics, by atomic absorption spectroscopy (AAS), ATR-FTIR, thin-film x-ray diffraction (TF-XRD), scanning electron microscopy (SEM), and microtensile bond strength (μTBS). The tested functional monomers were 2-MEP (two-carbon spacer chain), 10-MDP (10-carbon), 12-MDDP (12-carbon), MTEP (more hydrophilic polyether spacer chain), and CAP-P (intermediate hydrophilicity ester spacer). The intensity of monomer-calcium salt formation measured by AAS differed in the order of 12-MDDP=10-MDP>CAP-P>MTEP>2-MEP. FTIR and SEM analyses of monomer-treated dentin surfaces showed resistance to rinsing for all monomer-dentin bonds, except with 2-MEP. TF-XRD confirmed the weaker interaction of 2-MEP. Highest µTBS was observed for 12-MDDP and 10-MDP. A shorter spacer chain (2-MEP) of phosphate functional monomers induced formation of unstable monomer-calcium salts, and lower chemical interaction and dentin bond strength. The presence of ester or ether groups within longer spacer carbon chains (CAP-P and MTEP) may affect the hydrophilicity, μTBS, and also the formation of monomer-calcium salts.

  19. Experimental Study of Water Transport through Hydrophilic Nanochannels

    Science.gov (United States)

    Alibakhshi, Mohammad Amin; Xie, Quan; Li, Yinxiao; Duan, Chuanhua

    2015-11-01

    In this paper, we investigate one of the fundamental aspects of Nanofluidics, which is the experimental study of water transport through nanoscale hydrophilic conduits. A new method based on spontaneous filling and a novel hybrid nanochannel design is developed to measure the pure mass flow resistance of single nanofluidic channels/tubes. This method does not require any pressure and flow sensors and also does not rely on any theoretical estimations, holding the potential to be standards for nanofluidic flow characterization. We have used this method to measure the pure mass flow resistance of single 2-D hydrophilic silica nanochannels with heights down to 7 nm. Our experimental results quantify the increased mass flow resistance as a function of nanochannel height, showing a 45% increase for a 7nm channel compared with classical hydrodynamics, and suggest that the increased resistance is possibly due to formation of a 7-angstrom-thick stagnant hydration layer on the hydrophilic surfaces. It has been further shown that this method can reliably measure a wide range of pure mass flow resistances of nanoscale conduits, and thus is promising for advancing studies of liquid transport in hydrophobic graphene nanochannels, CNTs, as well as nanoporous media. The work is supported by the American Chemical Society Petroleum Research Fund (ACS PRF # 54118-DNI7) and the Faculty Startup Fund (Boston University, USA).

  20. A Comparative Study of Hydrophilic Modification of Polypropylene Membranes by Remote and Direct Ar Plasma

    Institute of Scientific and Technical Information of China (English)

    ZHANG Suzhen; CHENG Cheng; LAN Yan; MENG Yuedong

    2009-01-01

    Surface modification of polypropylene membrane by argon (Ar) plasma-induced graft polymerization with hydrophilic monomer [acrylic acid (AA) in this work]was investigated.It was found that both the distance of the membrane from the Ar plasma center and the plasma power had a strong influence on the surface modification,hydrophilicity and graft yield (GY) of the treated membrane.Results suggest that remote plasma treatment with a proper sample position,plasma power and graft polymerization leads to a membrane surface with not only less damage,but also more permanent hydrophilicity,than direct plasma treatment does.By analyzing the morphology and the chemical composition of the membrane surface by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS),as well as Fourier transform infrared attenuated total reflection spectroscopy (FTIR-ATR) respectively,a possible mechanism was tentatively revealed.

  1. Surface color perception and equivalent illumination models.

    Science.gov (United States)

    Brainard, David H; Maloney, Laurence T

    2011-05-02

    Vision provides information about the properties and identity of objects. The ease with which we perceive object properties belies the difficulty of the underlying information-processing task. In the case of object color, retinal information about object reflectance is confounded with information about the illumination as well as about the object's shape and pose. There is no obvious rule that allows transformation of the retinal image to a color representation that depends primarily on object surface reflectance. Under many circumstances, however, object color appearance is remarkably stable across scenes in which the object is viewed. Here, we review a line of experiments and theory that aim to understand how the visual system stabilizes object color appearance. Our emphasis is on models derived from explicit analysis of the computational problem of estimating the physical properties of illuminants and surfaces from the retinal image, and experiments that test these models. We argue that this approach has considerable promise for allowing generalization from simplified laboratory experiments to richer scenes that more closely approximate natural viewing. We discuss the relation between the work we review and other theoretical approaches available in the literature.

  2. Mycorrhizal fungi and global land surface models?

    Science.gov (United States)

    Brzostek, E. R.; Fisher, J. B.; Shi, M.; Phillips, R.

    2013-12-01

    In the current generation of Land Surface Models (LSMs), the representation of coupled carbon (C) and nutrient cycles does not account for allocation of C by plants to mycorrhizal fungi in exchange for limiting nutrients. Given that the amount of C transferred to mycorrhizae can exceed 20% of net primary production (NPP), mycorrhizae can supply over half of the nitrogen (N) needed to support NPP, and that large majority of plants form associations with mycorrhizae; integrating these mechanisms into LSMs may significantly alter our understanding of the role of the terrestrial biosphere in mitigating climate change. Here, we present results from the integration of a mycorrhizal framework into a cutting-edge global plant nitrogen model -- Fixation & Uptake of Nitrogen (FUN; Fisher et al., 2010) -- that can be coupled into existing LSMs. In this mycorrhizal framework, the C cost of N acquisition varies as a function of mycorrhizal type with: (1) plants that support arbuscular mycorrhizae (AM) benefiting when N is plentiful and (2) plants that support ectomycorrhizae (ECM) benefiting when N is limiting. At the plot scale (15 x 15m), the My-FUN model improved predictions of retranslocation, N uptake, and the amount of C transferred into the soil relative to the base model across 45 plots that vary in mycorrhizal type in Indiana, USA. At the ecosystem scale, when we coupled this new framework into the Community Land Model (CLM-CN), the model estimated lower C uptake than the base model and more accurately predicted C uptake at the Morgan Monroe State Forest AmeriFlux site. These results suggest that the inclusion of a mycorrhizal framework into LSMs will enhance our ability to predict feedbacks between global change and the terrestrial biosphere.

  3. Bioadhesion to model thermally responsive surfaces

    Science.gov (United States)

    Andrzejewski, Brett Paul

    This dissertation focuses on the characterization of two surfaces: mixed self-assembled monolayers (SAMs) of hexa(ethylene glycol) and alkyl thiolates (mixed SAM) and poly(N-isopropylacrylamide) (PNIPAAm). The synthesis of hexa(ethylene gylcol) alkyl thiol (C11EG 6OH) is presented along with the mass spectrometry and nuclear magnetic resonance results. The gold substrates were imaged prior to SAM formation with atomic force micrscopy (AFM). Average surface roughness of the gold substrate was 0.44 nm, 0.67 nm, 1.65 nm for 15, 25 and 60 nm gold thickness, respectively. The height of the mixed SAM was measured by ellipsometry and varied from 13 to 28°A depending on surface mole fraction of C11EG6OH. The surface mole fraction of C11EG6OH for the mixed SAM was determined by X-ray photoelectron spectroscopy (XPS) with optimal thermal responsive behavior in the range of 0.4 to 0.6. The mixed SAM surface was confirmed to be thermally responsive by contact angle goniometry, 35° at 28°C and ˜55° at 40°C. In addition, the mixed SAM surfaces were confirmed to be thermally responsive for various aqueous mediums by tensiometry. Factors such as oxygen, age, and surface mole fraction and how they affect the thermal responsive of the mixed SAM are discussed. Lastly, rat fibroblasts were grown on the mixed SAM and imaged by phase contrast microscopy to show inhibition of attachment at temperatures below the molecular transition. Qualitative and quantitative measurements of the fibroblast adhesion data are provided that support the hypothesis of the mixed SAM exhibits a dominantly non-fouling molecular conformation at 25°C whereas it exhibits a dominantly fouling molecular conformation at 40°C. The adhesion of six model proteins: bovine serum albumin, collagen, pyruvate kinase, cholera toxin subunit B, ribonuclease, and lysozyme to the model thermally responsive mixed SAM were examined using AFM. All six proteins possessed adhesion to the pure component alkyl thiol, in

  4. Merging Digital Surface Models Implementing Bayesian Approaches

    Science.gov (United States)

    Sadeq, H.; Drummond, J.; Li, Z.

    2016-06-01

    In this research different DSMs from different sources have been merged. The merging is based on a probabilistic model using a Bayesian Approach. The implemented data have been sourced from very high resolution satellite imagery sensors (e.g. WorldView-1 and Pleiades). It is deemed preferable to use a Bayesian Approach when the data obtained from the sensors are limited and it is difficult to obtain many measurements or it would be very costly, thus the problem of the lack of data can be solved by introducing a priori estimations of data. To infer the prior data, it is assumed that the roofs of the buildings are specified as smooth, and for that purpose local entropy has been implemented. In addition to the a priori estimations, GNSS RTK measurements have been collected in the field which are used as check points to assess the quality of the DSMs and to validate the merging result. The model has been applied in the West-End of Glasgow containing different kinds of buildings, such as flat roofed and hipped roofed buildings. Both quantitative and qualitative methods have been employed to validate the merged DSM. The validation results have shown that the model was successfully able to improve the quality of the DSMs and improving some characteristics such as the roof surfaces, which consequently led to better representations. In addition to that, the developed model has been compared with the well established Maximum Likelihood model and showed similar quantitative statistical results and better qualitative results. Although the proposed model has been applied on DSMs that were derived from satellite imagery, it can be applied to any other sourced DSMs.

  5. MERGING DIGITAL SURFACE MODELS IMPLEMENTING BAYESIAN APPROACHES

    Directory of Open Access Journals (Sweden)

    H. Sadeq

    2016-06-01

    Full Text Available In this research different DSMs from different sources have been merged. The merging is based on a probabilistic model using a Bayesian Approach. The implemented data have been sourced from very high resolution satellite imagery sensors (e.g. WorldView-1 and Pleiades. It is deemed preferable to use a Bayesian Approach when the data obtained from the sensors are limited and it is difficult to obtain many measurements or it would be very costly, thus the problem of the lack of data can be solved by introducing a priori estimations of data. To infer the prior data, it is assumed that the roofs of the buildings are specified as smooth, and for that purpose local entropy has been implemented. In addition to the a priori estimations, GNSS RTK measurements have been collected in the field which are used as check points to assess the quality of the DSMs and to validate the merging result. The model has been applied in the West-End of Glasgow containing different kinds of buildings, such as flat roofed and hipped roofed buildings. Both quantitative and qualitative methods have been employed to validate the merged DSM. The validation results have shown that the model was successfully able to improve the quality of the DSMs and improving some characteristics such as the roof surfaces, which consequently led to better representations. In addition to that, the developed model has been compared with the well established Maximum Likelihood model and showed similar quantitative statistical results and better qualitative results. Although the proposed model has been applied on DSMs that were derived from satellite imagery, it can be applied to any other sourced DSMs.

  6. Hydrophilicity of dentin bonding systems influences in vitro Streptococcus mutans biofilm formation

    Science.gov (United States)

    Brambilla, Eugenio; Ionescu, Andrei; Mazzoni, Annalisa; Cadenaro, Milena; Gagliani, Massimo; Ferraroni, Monica; Tay, Franklin; Pashley, David; Breschi, Lorenzo

    2014-01-01

    Objectives To evaluate in vitro Streptococcus mutans (S. mutans) biofilm formation on the surface of five light-curing experimental dental bonding systems (DBS) with increasing hydrophilicity. The null hypothesis tested was that resin chemical composition and hydrophilicity does not affect S. mutans biofilm formation. Methods Five light-curing versions of experimental resin blends with increasing hydrophilicity were investigated (R1, R2, R3, R4 and R5). R1 and R2 contained ethoxylated BisGMA/TEGDMA or BisGMA/TEGDMA, respectively, and were very hydrophobic, were representative of pit-and-fissure bonding agents. R3 was representative of a typical two-step etch- and-rinse adhesive, while R4 and R5 were very hydrophilic resins analogous to self-etching adhesives. Twenty-eight disks were prepared for each resin blend. After a 24 h-incubation at 37 °C, a multilayer monospecific biofilm of S. mutans was obtained on the surface of each disk. The adherent biomass was determined using the MTT assay and evaluated morphologically with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). Results R2 and R3 surfaces showed the highest biofilm formation while R1 and R4 showed a similar intermediate biofilm formation. R5 was more hydrophilic and acidic and was significantly less colonized than all the other resins. A significant quadratic relationship between biofilm formation and hydrophilicity of the resin blends was found. CLSM and SEM evaluation confirmed MTT assay results. Conclusions The null hypothesis was rejected since S. mutans biofilm formation was influenced by hydrophilicity, surface acidity and chemical composition of the experimental resins. Further studies using a bioreactor are needed to confirm the results and clarify the role of the single factors. PMID:24954666

  7. Hydrophilicity of dentin bonding systems influences in vitro Streptococcus mutans biofilm formation.

    Science.gov (United States)

    Brambilla, Eugenio; Ionescu, Andrei; Mazzoni, Annalisa; Cadenaro, Milena; Gagliani, Massimo; Ferraroni, Monica; Tay, Franklin; Pashley, David; Breschi, Lorenzo

    2014-08-01

    To evaluate in vitro Streptococcus mutans (S. mutans) biofilm formation on the surface of five light-curing experimental dental bonding systems (DBS) with increasing hydrophilicity. The null hypothesis tested was that resin chemical composition and hydrophilicity does not affect S. mutans biofilm formation. Five light-curing versions of experimental resin blends with increasing hydrophilicity were investigated (R1, R2, R3, R4 and R5). R1 and R2 contained ethoxylated BisGMA/TEGDMA or BisGMA/TEGDMA, respectively, and were very hydrophobic, were representative of pit-and-fissure bonding agents. R3 was representative of a typical two-step etch-and-rinse adhesive, while R4 and R5 were very hydrophilic resins analogous to self-etching adhesives. Twenty-eight disks were prepared for each resin blend. After a 24h-incubation at 37°C, a multilayer monospecific biofilm of S. mutans was obtained on the surface of each disk. The adherent biomass was determined using the MTT assay and evaluated morphologically with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). R2 and R3 surfaces showed the highest biofilm formation while R1 and R4 showed a similar intermediate biofilm formation. R5 was more hydrophilic and acidic and was significantly less colonized than all the other resins. A significant quadratic relationship between biofilm formation and hydrophilicity of the resin blends was found. CLSM and SEM evaluation confirmed MTT assay results. The null hypothesis was rejected since S. mutans biofilm formation was influenced by hydrophilicity, surface acidity and chemical composition of the experimental resins. Further studies using a bioreactor are needed to confirm the results and clarify the role of the single factors. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  8. Filling transitions on rough surfaces: inadequacy of Gaussian surface models

    CERN Document Server

    Dufour, Renaud; Herminghaus, Stephan

    2015-01-01

    We present numerical studies of wetting on various topographic substrates, including random topographies. We find good agreement with recent predictions based on an analytical interface-displacement-type theory \\cite{Herminghaus2012, Herminghaus2012a}. The phase diagrams are qualitatively as predicted, but differently in this study the critical points are found to lie within the physical parameter range (i.e., at positive contact angle) in all cases studied. Notably, it is corroborated that Gaussian random surfaces behave qualitatively different from all non-Gaussian topographies investigated, exhibiting a qualitatively different phase diagram. This shows that Gaussian random surfaces must be used with great care in the context of wetting phenomena.

  9. Effect of poly-L-arginine on intestinal absorption of hydrophilic macromolecules in rats.

    Science.gov (United States)

    Yamaki, Tsutomu; Uchida, Masaki; Kuwahara, Yusuke; Shimazaki, Yohei; Ohtake, Kazuo; Kimura, Mitsutoshi; Uchida, Hiroyuki; Kobayashi, Jun; Ogihara, Masahiko; Morimoto, Yasunori; Natsume, Hideshi

    2013-01-01

    We have already reported that poly-L-arginine (PLA) remarkably enhanced the in vivo nasal absorption of hydrophilic macromolecules without producing any significant epithelial damage in rats. In the present study, we examined whether PLA could enhance the absorption of a model hydrophilic macromolecule, fluorescein isothiocyanate-dextran (FD-4), across the intestinal mucosa, as well as the nasal mucosa, by an in situ closed-loop method using the rat intestine. PLA was found to enhance the intestinal absorption of FD-4 in a concentration-dependent manner within the concentrations investigated in this study, but segment-specific differences were found to be associated with this effect (ileum>jejunum>duodenum≧colon). The factors responsible for the segment-specific differences were also investigated by intestinal absorption studies using aprotinin, a trypsin inhibitor, and an analysis of the expression of occludin, a tight junction protein. In the small intestine, the differences in the effect of PLA on the absorption of FD-4 may be related to the enzymatic degradation of PLA. In the colon, the reduced effect of PLA on the absorption of FD-4 may be related to the smaller surface area for absorption and the higher expression of occludin compared with other segments.

  10. Preparation of hydrophilic vinyl chloride copolymer hollow fiber membranes with antifouling properties

    Science.gov (United States)

    Rajabzadeh, Saeid; Sano, Rie; Ishigami, Toru; Kakihana, Yuriko; Ohmukai, Yoshikage; Matsuyama, Hideto

    2015-01-01

    Hydrophilic vinyl chloride copolymer hollow fiber membranes with antifouling properties were prepared from brominated vinyl chloride-hydroxyethyl methacrylate copolymer (poly(VC-co-HEMA-Br)). The base membrane was grafted with two different zwitterionic monomers, (2-methacryloyloxyethylphosphorylcholine) (MPC) and [2-(methacryloyloxy) ethyl] dimethyl (3-sulfopropyl) ammonium hydroxide) (MEDSAH), and poly(ethylene glycol) methyl ether methacrylate (PEGMA). The effect of the grafting on the base membrane hydrophilicity and antifouling properties was investigated. For comparison of the results, the pure water permeabilities and pore sizes at the outer surfaces of the grafted hollow fiber membranes were controlled to be similar. A poly(VC-co-HEMA-Br) hollow fiber membrane with similar pure water permeability and pore size was also prepared as a control membrane. A BSA solution was used as a model fouling solution for evaluation of the antifouling properties. Grafting with zwitterionic monomers and PEGMA improved the antifouling properties compared with the control membrane. The PEGMA grafted membrane showed the best antifouling properties among the grafted membranes

  11. Influence of hydrophilic pre-treatment on resin bonding to zirconia ceramics.

    Science.gov (United States)

    Noro, Akio; Kameyama, Atsushi; Haruyama, Akiko; Takahashi, Toshiyuki

    2015-01-01

    Atmospheric plasma or ultraviolet (UV) treatment alters the surface characteristics of tetragonal zirconia polycrystal (TZP), increasing its hydrophilicity by reducing the contact angle against water to zero. This suggests that such treatment would increase the wettability of bonding resin. The purpose of this study was to determine how increasing the hydrophilicity of TZP through plasma irradiation, UV treatment, or application of ceramic primer affected initial bonding with resin composites. Here, the effect of each pre-treatment on the hydrophilicity of TZP surfaces was determined by evaluating change in shear bond strength. Plasma irradiation, UV, or ceramic primer pre-treatment showed no significant effect on bonding strength between TZP surfaces and resin composites. In addition, alumina blasting yielded no significant increase in bond strength. Plasma irradiation, UV treatment, or ceramic primer pre-treatment did not lead to significant increase in bond strength between TZP and resin composites.

  12. Atomistic modelling of evaporation and explosive boiling of thin film liquid argon over internally recessed nanostructured surface

    Science.gov (United States)

    Hasan, Mohammad Nasim; Shavik, Sheikh Mohammad; Rabbi, Kazi Fazle; Haque, Mominul

    2016-07-01

    Molecular dynamics (MD) simulations have been carried out to investigate evaporation and explosive boiling phenomena of thin film liquid argon on nanostructured solid surface with emphasis on the effect of solid-liquid interfacial wettability. The nanostructured surface considered herein consists of trapezoidal internal recesses of the solid platinum wall. The wetting conditions of the solid surface were assumed such that it covers both the hydrophilic and hydrophobic conditions and hence effect of interfacial wettability on resulting evaporation and boiling phenomena was the main focus of this study. The initial configuration of the simulation domain comprised of a three phase system (solid platinum, liquid argon and vapor argon) on which equilibrium molecular dynamics (EMD) was performed to reach equilibrium state at 90 K. After equilibrium of the three-phase system was established, the wall was set to different temperatures (130 K and 250 K for the case of evaporation and explosive boiling respectively) to perform non-equilibrium molecular dynamics (NEMD). The variation of temperature and density as well as the variation of system pressure with respect to time were closely monitored for each case. The heat flux normal to the solid surface was also calculated to illustrate the effectiveness of heat transfer for hydrophilic and hydrophobic surfaces in cases of both nanostructured surface and flat surface. The results obtained show that both the wetting condition of the surface and the presence of internal recesses have significant effect on normal evaporation and explosive boiling of the thin liquid film. The heat transfer from solid to liquid in cases of surface with recesses are higher compared to flat surface without recesses. Also the surface with higher wettability (hydrophilic) provides more favorable conditions for boiling than the low-wetting surface (hydrophobic) and therefore, liquid argon responds quickly and shifts from liquid to vapor phase faster in

  13. A surface hydrology model for regional vector borne disease models

    Science.gov (United States)

    Tompkins, Adrian; Asare, Ernest; Bomblies, Arne; Amekudzi, Leonard

    2016-04-01

    Small, sun-lit temporary pools that form during the rainy season are important breeding sites for many key mosquito vectors responsible for the transmission of malaria and other diseases. The representation of this surface hydrology in mathematical disease models is challenging, due to their small-scale, dependence on the terrain and the difficulty of setting soil parameters. Here we introduce a model that represents the temporal evolution of the aggregate statistics of breeding sites in a single pond fractional coverage parameter. The model is based on a simple, geometrical assumption concerning the terrain, and accounts for the processes of surface runoff, pond overflow, infiltration and evaporation. Soil moisture, soil properties and large-scale terrain slope are accounted for using a calibration parameter that sets the equivalent catchment fraction. The model is calibrated and then evaluated using in situ pond measurements in Ghana and ultra-high (10m) resolution explicit simulations for a village in Niger. Despite the model's simplicity, it is shown to reproduce the variability and mean of the pond aggregate water coverage well for both locations and validation techniques. Example malaria simulations for Uganda will be shown using this new scheme with a generic calibration setting, evaluated using district malaria case data. Possible methods for implementing regional calibration will be briefly discussed.

  14. SMART SURFACE SWITCHING FROM OLEOPHOBIC/HYDROPHOBIC TO HYDROPHILIC:SHORT PERFLUOROALKYL-CONTAINING COPOLYMER TREATED COTTON FABRICS%含短碳氟链聚合物处理的织物表面疏水/疏油-亲水转换特性的研究

    Institute of Scientific and Technical Information of China (English)

    蔡雪刁; 黄茹; 左蕊红; 刘洋; 卢先明

    2013-01-01

    采用半连续加入乳液聚合的方法合成了含不同长度氟碳链的丙烯酸酯-丙烯酸共聚物.通过傅里叶变换红外光谱(Fr-IR)和热重分析(TGA)对聚合物的组成、热稳定性等性质进行了表征,详细考察了不同氟碳链对聚合物性质的影响,经聚合物乳液整理后织物的水接触角和二碘甲烷接触角显示出织物表面具有良好的疏水疏油性,与长氟烷基链聚合物相比有相同的特性;此外,接触角、荧光显微镜以及元素面分布结果表明,整理后的织物具有疏水/疏油-亲水性转换功能,这对于织物的抗污及清洗具有良好的作用.%Novel poly(perfluoroalkylated acrylate-acrylic acid) [P(PFAA-AA)] copolymers were prepared by the emulsion copolymerization of short chain perfluoroalkyl-containing acrylate with acrylic acid. Copolymers were characterized with FT-IR and their thermal stabilities were studied by TGA. These copolymers were used to treat cotton fabrics. A smart surface switching from olephobic/hydrophobic to hydrophilic on treated fabrics was observed. The change behavior of oleophobicity/hydrophobicity to hydrophilicity was investigated by elemental map and fluorography. The mechanism of smart surface was proposed.

  15. Properties of mixed monolayers of clinical lung surfactant, serum albumin and hydrophilic polymers.

    Science.gov (United States)

    Minkov, I; Mircheva, K; Grozev, N; Tz, Ivanova; Panaiotov, I

    2013-01-01

    It is now established that the surface activity of the clinically used lung surfactant is reduced by serum proteins and can be restored by adding the hydrophilic polymers. The mechanisms of lung surfactant inactivation by serum proteins and restoring effect by the hydrophilic polymers remain not completely understood. In this paper the state and rheological dilatational properties of surface films formed from clinical lung surfactant Exosurf, Survanta, Curosurf and Alveofact in the presence of serum albumin (BSA) and hydrophilic polymers polyvinylpyrrolidone (PVP), polyethylene glycol (PEG) and Dextran were studied. The obtained results suggest that the lung surfactant and BSA mixtures spread at air-water interface form a DPPC/BSA mixed monolayers with lower content of DPPC. The presence of hydrophilic polymers PVP, PEG and Dextran restore the DPPC content in the surface film. The effectiveness of the DPPC spreading and formation of better compacted film increases in order Exosurf, Survanta, Curosurf, Alveofact. The obtained results are in accordance with the generally admitted ideas about the mechanisms of serum protein inactivation and restoring effect of hydrophilic polymers based on the previously studies of the lung surfactant adsorption rate.

  16. Tratamento de superfície de tubos de poliamida 11 com chama para deposição de revestimento hidrofílico biomédico Flame surface treatment of polyamide 11 tubes for the deposition of biomedical hydrophilic coatings

    Directory of Open Access Journals (Sweden)

    Waldemar F. M. Martins

    2010-09-01

    Full Text Available O processo para obtenção de uma camada polimérica hidrofílica sobre um componente polimérico pode ser basicamente dividido em: tratamento de superfície do substrato, aplicação e cura do revestimento. O tratamento de superfície se faz necessário em função da grande diferença de polaridade comumente apresentada entre os materiais que compõem este conjunto e da baixa energia livre de superfície inerente aos principais materiais utilizados como substrato, fatores estes que dificultam a adesão entre eles. Neste trabalho foi avaliada a influência da técnica de tratamento de superfície através de exposição à chama sobre a tentativa de aumento da energia livre de superfície de tubos de poliamida 11. Amostras foram submetidas ao tratamento durante 5, 10, 20, 30 e 60 segundos, e posteriormente caracterizadas por goniometria, microscopia eletrônica de varredura, espectroscopia de infravermelho e resistência ao risco da camada depositada. Amostras não tratadas foram analisadas como parâmetro de controle das modificações. Os resultados mostraram um aumento da molhabilidade e rugosidade da superfície, além de uma melhoria na adesão da camada hidrofílica após o tratamento.The process of obtaining a hydrophilic polymer coating on a polymeric component or product can be basically divided into: the substrate surface treatment, the coating application and the cross-linking. The substrate surface treatment is crucial due to the possible large difference in polarity between the polymers and the substrate materials, which commonly have low free surface energy and may severely hamper adhesion. This study evaluated the influence of flame surface treatment for the attempt of increasing the free energy surface of polyamide 11 tubes. Samples were submitted to treatment for 5, 10, 20, 30 and 60 seconds, and subsequently characterized by goniometry, scanning electron microscopy, infrared spectroscopy and scratch resistance of the deposited

  17. A two-surface plasticity model for stiff clay

    OpenAIRE

    2015-01-01

    This paper presents a constitutive model for describing some important features of the behavior of natural stiff clay evidenced experimentally such as the limited elastic zone, the presence of strain hardening and softening, and the smooth transition from elastic behavior to a plastic one. The model, namely ACC-2, is an adapted Modified Cam Clay model with two yield surfaces: similarly to bounding surface plasticity theory, an additional yield surface?namely Inner yield surface?was adopted to...

  18. Influence of hydrophilic polymers on the complexation of carbamazepine with hydroxypropyl-β-cyclodextrin.

    Science.gov (United States)

    Medarević, Djordje; Kachrimanis, Kyriakos; Djurić, Zorica; Ibrić, Svetlana

    2015-10-12

    In this study binary carbamazepine-hydroxypropyl-β-cyclodextrin, as well as ternary carbamazepine-hydroxypropyl-β-cyclodextrin-hydrophilic polymer systems were used to improve dissolution rate of carbamazepine. It has been shown that addition of hydrophilic polymers (Soluplus® and two types of hydroxypropyl methylcellulose-Metolose® 90SH-100 and Metolose® 65SH-1500) significantly increased solubilization capacity of hydroxypropyl-β-cyclodextrin for carbamazepine. Evaluation of carbamazepine-hydroxypropyl-β-cyclodextrin-hydrophilic polymer interactions using molecular modeling techniques showed interactions between carbamazepine, which dissociates from inclusion complexes and hydroxypropyl methylcellulose that can prevent crystallization of dissolved carbamazepine. These results can contribute to better understanding of drug-cyclodextrin-hydrophilic polymer interactions which are still not well understood. After evaluation of carbamazepine solubilization with hydroxypropyl-β-cyclodextrin and hydrophilic polymers, both binary carbamazepine-hydroxypropyl-β-cyclodextrin and ternary carbamazepine-hydroxypropyl-β-cyclodextrin-hydrophilic polymer systems were prepared by spray drying. The results of solid state characterization methods showed amorphous nature of carbamazepine in all spray dried systems, which together with the results of molecular modeling techniques indicates inclusion complex formation. Carbamazepine dissolution rate was significantly improved from spray dried formulations compared to pure drug. Binary carbamazepine-hydroxypropyl-β-cyclodextrin and ternary carbamazepine-hydroxypropyl-β-cyclodextrin-Soluplus® systems exhibited the fastest carbamazepine release, wherein the entire amount of carbamazepine was released during first 5 min.

  19. Sum Frequency Generation Vibrational Spectroscopy of Adsorbed Amino Acids, Peptides and Proteins of Hydrophilic and Hydrophobic Solid-Water Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Holinga IV, George Joseph [Univ. of California, Berkeley, CA (United States)

    2010-09-01

    Sum frequency generation (SFG) vibrational spectroscopy was used to investigate the interfacial properties of several amino acids, peptides, and proteins adsorbed at the hydrophilic polystyrene solid-liquid and the hydrophobic silica solid-liquid interfaces. The influence of experimental geometry on the sensitivity and resolution of the SFG vibrational spectroscopy technique was investigated both theoretically and experimentally. SFG was implemented to investigate the adsorption and organization of eight individual amino acids at model hydrophilic and hydrophobic surfaces under physiological conditions. Biointerface studies were conducted using a combination of SFG and quartz crystal microbalance (QCM) comparing the interfacial structure and concentration of two amino acids and their corresponding homopeptides at two model liquid-solid interfaces as a function of their concentration in aqueous solutions. The influence of temperature, concentration, equilibration time, and electrical bias on the extent of adsorption and interfacial structure of biomolecules were explored at the liquid-solid interface via QCM and SFG. QCM was utilized to quantify the biological activity of heparin functionalized surfaces. A novel optical parametric amplifier was developed and utilized in SFG experiments to investigate the secondary structure of an adsorbed model peptide at the solid-liquid interface.

  20. Modeling of laser induced periodic surface structures

    NARCIS (Netherlands)

    Skolski, J.Z.P.; Römer, G.R.B.E.; Huis in 't Veld, A.J.; Mitko, V.S.; Obona, J.V.; Ocelik, V.; Hosson, J.T.M. de

    2010-01-01

    In surfaces irradiated by short laser pulses, Laser Induced Periodic Surface Structures (LIPSS) have been observed on all kind of materials for over forty years. These LIPSS, also referred to as ripples, consist of wavy surfaces with periodicity equal or smaller than the wavelength of the laser radi

  1. Periodicity-dependent stiffness of periodic hydrophilic-hydrophobic heteropolymers

    Science.gov (United States)

    Chowdhury, Debashish; Stauffer, Dietrich; Strey, Reinhard

    1999-08-01

    From extensive Monte Carlo simulations of a Larson model of perfectly periodic heteropolymers (PHP) in water, a striking stiffening is observed as the period of the alternating hydrophobic and hydrophilic blocks is shortened. At short period and low temperature needlelike conformations are the stable conformations. As temperature is increased thermal fluctuations induce kinks and bends. At large periods compact oligomeric globules are observed. From the generalized Larson prescription, originally developed for modeling surfactant molecules in aqueous solutions, we find that the shorter the period is the more stretched the PHP is. This novel effect is expected to stimulate polymer synthesis and trigger research on the rheology of aqueous periodic heteropolymer solutions.

  2. Three-gradient regular solution model for simple liquids wetting complex surface topologies

    Directory of Open Access Journals (Sweden)

    Sabine Akerboom

    2016-10-01

    Full Text Available We use regular solution theory and implement a three-gradient model for a liquid/vapour system in contact with a complex surface topology to study the shape of a liquid drop in advancing and receding wetting scenarios. More specifically, we study droplets on an inverse opal: spherical cavities in a hexagonal pattern. In line with experimental data, we find that the surface may switch from hydrophilic (contact angle on a smooth surface θY 90°. Both the Wenzel wetting state, that is cavities under the liquid are filled, as well as the Cassie–Baxter wetting state, that is air entrapment in the cavities under the liquid, were observed using our approach, without a discontinuity in the water front shape or in the water advancing contact angle θ. Therefore, air entrapment cannot be the main reason why the contact angle θ for an advancing water front varies. Rather, the contact line is pinned and curved due to the surface structures, inducing curvature perpendicular to the plane in which the contact angle θ is observed, and the contact line does not move in a continuous way, but via depinning transitions. The pinning is not limited to kinks in the surface with angles θkink smaller than the angle θY. Even for θkink > θY, contact line pinning is found. Therefore, the full 3D-structure of the inverse opal, rather than a simple parameter such as the wetting state or θkink, determines the final observed contact angle.

  3. Hydrophilic fluorescent nanogel thermometer for intracellular thermometry.

    Science.gov (United States)

    Gota, Chie; Okabe, Kohki; Funatsu, Takashi; Harada, Yoshie; Uchiyama, Seiichi

    2009-03-01

    The first methodology to measure intracellular temperature is described. A highly hydrophilic fluorescent nanogel thermometer developed for this purpose stays in the cytoplasm and emits stronger fluorescence at a higher temperature. Thus, intracellular temperature variations associated with biological processes can be monitored by this novel thermometer with a temperature resolution of better than 0.5 degrees C.

  4. Closed surface modeling with helical line measurement data

    Institute of Scientific and Technical Information of China (English)

    LI Ruqiong; LI Guanghu; WANG Yuhan

    2007-01-01

    Models for surface modeling of free-form surface and massive data points are becoming an important feature in commercial computer aided design/computer-aided manu- facturing software. However, there are many problems to be solved in this area, especially for closed free-form surface modeling. This article presents an effective method for cloud data closed surface modeling from asynchronous profile modeling measurement. It includes three steps: first, the cloud data are preprocessed for smoothing; second, a helical line is segmented to form triangle meshes; and third, Bezier surface patches are created over a triangle mesh and trimmed to shape on an entire surface. In the end, an illustrative example of shoe last surface modeling is given to show the availability of this method.

  5. Surface CUrrents from a Diagnostic model (SCUD): Pacific

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The SCUD data product is an estimate of upper-ocean velocities computed from a diagnostic model (Surface CUrrents from a Diagnostic model). This model makes daily...

  6. Stability of triglyceride liquid films on hydrophilic and hydrophobic glasses.

    Science.gov (United States)

    Vazquez, Rosa; Nogueira, Rui; Orfão, Marta; Mata, José Luís; Saramago, Benilde

    2006-07-01

    Wetting and dewetting of solid surfaces by oily fluids were investigated in terms of the stability of the liquid film formed between an air bubble and the solid surface. With the objective of understanding how molecules with low polarity but relatively complex molecular structure behave at the solid/liquid interface, three liquid triglycerides with different chain length and saturation were chosen, namely, tributyrin, tricaprylin, and triolein. Tributyrin and tricaprylin exist in milkfat while triolein is present in vegetable oils. The stability of the liquid films may be inferred from the shape of the disjoining pressure isotherms, which represent the dependence of the disjoining pressure on the film thickness. Disjoining pressure isotherms for films of the three triglycerides on hydrophilic and hydrophobic glasses were obtained using a recently developed apparatus, based on the interferometric technique. The experimental curves are compared with the theoretical predictions of London-Hamaker. The deviations between theory and experiment are interpreted in terms of a structural component of the disjoining pressure. All triglycerides form metastable films on both hydrophilic and hydrophobic glasses which means that for disjoining pressures higher than a critical value, pi(c), a wetting transition occurs and the film ruptures. The mechanisms for film rupture are discussed and a correlation between film stability and the apolar (Lifshitz-van der Waals) and the polar components of the spreading coefficient is proposed.

  7. On hydrophilicity improvement of the porous anodic alumina film by hybrid nano/micro structuring

    Science.gov (United States)

    Wang, Weichao; Zhao, Wei; Wang, Kaige; Wang, Lei; Wang, Xuewen; Wang, Shuang; Zhang, Chen; Bai, Jintao

    2017-09-01

    In both, laboratory and industry, tremendous attention is paid to discover an effective technique to produce uniform, controllable and (super) hydrophilic surfaces over large areas that are useful in a wide range of applications. In this investigation, by combing porous anodic alumina (PAA) film with nano-structures and microarray of aluminum, the hydrophilicity of hybrid nano-micro structure has been significantly improved. It is found some factors can affect the hydrophilicity of film, such as the size and aspect ratio of microarray, the thickness of nano-PAA film etc. Comparing with pure nano-PAA films and microarray, the hybrid nano-micro structure can provide uniform surface with significantly better hydrophilicity. The improvement can be up to 84%. Also, this technique exhibits good stability and repeatability for industrial production. By optimizing the thickness of nano-PAA film and aspect ratio of micro-structures, super-hydrophilicity can be reached. This study has obvious prospect in the fields of chemical industry, biomedical engineering and lab-on-a-chip applications.

  8. Influence of Annealing and UV Irradiation on Hydrophilicity of Ag-TiO Nanostructured Thin Films

    Directory of Open Access Journals (Sweden)

    Fanming Meng

    2012-01-01

    Full Text Available Ag-TiO2 nanostructured thin films with silver content of 5 vol% have been deposited on silicon, glass, and quartz substrates by RF magnetron sputtering and annealed in ambient air at 900°C for 15, 30, 60, 90, and 120 min. Their crystal structure, surface morphology, and hydrophilicity have been characterized by X-ray diffractometer, atomic force microscope, and water contact angle apparatus, respectively. The influence of annealing time and UV irradiation time on hydrophilic property of Ag-TiO2 thin films have been studied in detail. It is shown that annealing time influences crystal structure of Ag-TiO2 thin films. The unannealed film is amorphous and shows poor hydrophilicity. With the increase of annealing time from 15 to 120 min, the grain-size slowly increases and tends to uniformity. A suitable annealing time can significantly enhance the hydrophilic behavior of Ag-TiO2 films. Water contact angle decreases with the increase of irradiation time. The mechanism of hydrophilicity has been proposed and can be attributed to the increase of oxygen anion radicals O2− and reactive center of surface Ti3+.

  9. Mathematical Model of the Identical Slope Surface

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The formation of the identical slope surface and the method of construction are discussed. Onthe basement of building the parameter equation of variable-radius circle family envelope, the frequentlyused parameter equation of the identical slope surface of the top of taper moving along column helix,horizental arc and line is built. The equation can be used to construct the identical slope surface's con-tours, gradient lines and three dimensional figures correctly.

  10. Multiwalled Carbon Nanotube Deposition on Model Environmental Surfaces

    Science.gov (United States)

    Deposition of multiwalled carbon nanotubes (MWNTs) on model environmental surfaces was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Deposition behaviors of MWNTs on positively and negatively charged surfaces were in good agreement with Der...

  11. Multiwalled Carbon Nanotube Deposition on Model Environmental Surfaces

    Science.gov (United States)

    Deposition of multiwalled carbon nanotubes (MWNTs) on model environmental surfaces was investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Deposition behaviors of MWNTs on positively and negatively charged surfaces were in good agreement with Der...

  12. Modelling and control of laser surface treatment

    NARCIS (Netherlands)

    Römer, Gerardus Richardus Benardus Engelina

    1999-01-01

    The results of laser surface treatment may vary significantly during laser surface processing. These variations arise from the sensitivity of the process to disturbances, such as varying absorptivity and the small dimensions of the work piece. To increase the reproducibility of the process, a real-t

  13. Modelling and control of laser surface treatment

    NARCIS (Netherlands)

    Römer, Gerardus Richardus, Bernardus, Engelina

    1999-01-01

    The results of laser surface treatment may vary significantly during laser surface processing. These variations arise from the sensitivity of the process to disturbances, such as varying absorptivity and the small dimensions of the work piece. To increase the reproducibility of the process, a

  14. Assembly of light-emitting diode based on hydrophilic CdTe quantum dots incorporating dehydrated silica gel.

    Science.gov (United States)

    Du, Jinhua; Wang, Chunlei; Xu, Xiaojing; Wang, Zhuyuan; Xu, Shuhong; Cui, Yiping

    2016-03-01

    Stable photoluminescence QD light-emitting diodes (QD-LEDs) were made based on hydrophilic CdTe quantum dots (QDs). A quantum dot-inorganic nanocomposite (hydrophilic CdTe QDs incorporating dehydrated silica gel) was prepared by two methods (rotary evaporation and freeze drying). Taking advantage of its viscosity, plasticity and transparency, dehydrated silica gel could be coated on the surface of ultraviolet (UV) light LEDs to make photoluminescence QD-LEDs. This new photoluminescence QD-LED, which is stable, environmentally non-toxic, easy to operate and low cost, could expand the applications of hydrophilic CdTe QDs in photoluminescence. Copyright © 2015 John Wiley & Sons, Ltd.

  15. New hydrophilic interaction/reversed-phase mixed-mode stationary phase and its application for analysis of nonionic ethoxylated surfactants.

    Science.gov (United States)

    Liu, Xiaodong; Pohl, Christopher

    2008-05-16

    We have developed a new stationary phase that combines both hydrophilic interaction and reversed-phase characteristics. The new phase is based on high-purity, porous and spherical silica gel functionalized with a silyl ligand consisting of both hydrophilic and hydrophobic functionalities. This phase can be operated in both HILIC mode (high organic solvent) and RPLC mode (low organic solvent). An optimal balance of hydrophilic and hydrophobic moieties on the silica surface provides unique chromatographic properties that make it useful for determination of alkyl chain distribution and degree of ethoxylation (EO number) of nonionic ethoxylated surfactants.

  16. Preparation of hydrophilic molecularly imprinted polymers for tetracycline antibiotics recognition

    Institute of Scientific and Technical Information of China (English)

    Peng Wang; Xiao Fang Fu; Jing Li; Jing Luo; Xiao Ya Zhao; Ming Jun Sun; Yin Zhu Shang; Cheng Ye

    2011-01-01

    Hydrophilic molecularly imprinted polymers (MIPs) were prepared using tetracycline as template, methacrylic acid as monomer and glycidilmethacrylate as pro-hydrophilic co-monomer. Compared with common MIPs, the imprinting effect and adsorption amounts of hydrophilic MIPs for tetracycline (TC) were greatly improved in water media. Furthermore, the electrochemical sensor fabricated by modifying hydrophilic MIPs on glassy carbon electrode was developed for the determination of TC in foodstuff samples.

  17. 21 CFR 872.3300 - Hydrophilic resin coating for dentures.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Hydrophilic resin coating for dentures. 872.3300... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3300 Hydrophilic resin coating for dentures. (a) Identification. A hydrophilic resin coating for dentures is a device that consists of a...

  18. Model castings with composite surface layer - application

    Directory of Open Access Journals (Sweden)

    J. Szajnar

    2008-10-01

    Full Text Available The paper presents a method of usable properties of surface layers improvement of cast carbon steel 200–450, by put directly in foundingprocess a composite surface layer on the basis of Fe-Cr-C alloy. Technology of composite surface layer guarantee mainly increase inhardness and aberasive wear resistance of cast steel castings on machine elements. This technology can be competition for generallyapplied welding technology (surfacing by welding and thermal spraying. In range of studies was made cast steel test castings withcomposite surface layer, which usability for industrial applications was estimated by criterion of hardness and aberasive wear resistance of type metal-mineral and quality of joint cast steel – (Fe-Cr-C. Based on conducted studies a thesis, that composite surface layer arise from liquid state, was formulated. Moreover, possible is control of composite layer thickness and its hardness by suitable selection of parameters i.e. thickness of insert, pouring temperature and solidification modulus of casting. Possibility of technology application of composite surface layer in manufacture of cast steel slide bush for combined cutter loader is presented.

  19. 21 CFR 201.319 - Water-soluble gums, hydrophilic gums, and hydrophilic mucilloids (including, but not limited to...

    Science.gov (United States)

    2010-04-01

    ... hydrophilic mucilloids (including, but not limited to agar, alginic acid, calcium polycarbophil... gum, kelp, methylcellulose, plantago seed (psyllium), polycarbophil tragacanth, and xanthan gum) as..., and hydrophilic mucilloids (including, but not limited to agar, alginic acid, calcium...

  20. Well-defined hydrophilic molecularly imprinted polymer microspheres for efficient molecular recognition in real biological samples by facile RAFT coupling chemistry.

    Science.gov (United States)

    Zhao, Man; Chen, Xiaojing; Zhang, Hongtao; Yan, Husheng; Zhang, Huiqi

    2014-05-12

    A facile and highly efficient new approach (namely RAFT coupling chemistry) to obtain well-defined hydrophilic molecularly imprinted polymer (MIP) microspheres with excellent specific recognition ability toward small organic analytes in the real, undiluted biological samples is described. It involves the first synthesis of "living" MIP microspheres with surface-bound vinyl and dithioester groups via RAFT precipitation polymerization (RAFTPP) and their subsequent grafting of hydrophilic polymer brushes by the simple coupling reaction of hydrophilic macro-RAFT agents (i.e., hydrophilic polymers with a dithioester end group) with vinyl groups on the "living" MIP particles in the presence of a free radical initiator. The successful grafting of hydrophilic polymer brushes onto the obtained MIP particles was confirmed by SEM, FT-IR, static contact angle and water dispersion studies, elemental analyses, and template binding experiments. Well-defined MIP particles with densely grafted hydrophilic polymer brushes (∼1.8 chains/nm(2)) of desired chemical structures and molecular weights were readily obtained, which showed significantly improved surface hydrophilicity and could thus function properly in real biological media. The origin of the high grafting densities of the polymer brushes was clarified and the general applicability of the strategy was demonstrated. In particular, the well-defined characteristics of the resulting hydrophilic MIP particles allowed the first systematic study on the effects of various structural parameters of the grafted hydrophilic polymer brushes on their water-compatibility, which is of great importance for rationally designing more advanced real biological sample-compatible MIPs.

  1. Modelling global fresh surface water temperature

    NARCIS (Netherlands)

    Beek, L.P.H. van; Eikelboom, T.; Vliet, M.T.H. van; Bierkens, M.F.P.

    2011-01-01

    Temperature directly determines a range of water physical properties including vapour pressure, surface tension, density and viscosity, and the solubility of oxygen and other gases. Indirectly water temperature acts as a strong control on fresh water biogeochemistry, influencing sediment

  2. Modelling global fresh surface water temperature

    NARCIS (Netherlands)

    Beek, L.P.H. van; Eikelboom, T.; Vliet, M.T.H. van; Bierkens, M.F.P.

    2011-01-01

    Temperature directly determines a range of water physical properties including vapour pressure, surface tension, density and viscosity, and the solubility of oxygen and other gases. Indirectly water temperature acts as a strong control on fresh water biogeochemistry, influencing sediment concentrati

  3. Bi-Spectrum Scattering Model for Dielectric Randomly Rough Surface

    Institute of Scientific and Technical Information of China (English)

    刘宁; 李宗谦

    2003-01-01

    The bistatic scattering model is offen used for remote microwave sensing. The bi-spectrum model (BSM) for conducting surfaces was used to develop a scattering model for dielectric randomly rough surfaces to estimate their bistatic scattering coefficients. The model for dielectric rough surfaces differs from the BSM for a conducting surface by including Fresnell reflection and transmission from dielectric rough surfaces. The bistatic scattering coefficients were defined to satisfy the reciprocal theorem. Values calculated using the BSM for dielectric randomly rough surfaces compare well with those of the integral equation model (IEM) and with experimental data, showing that the BSM accuracy is acceptable and its range of validity is similar to that of IEM while the BSM expression is simpler than that of IEM.

  4. Bi-Spectrum Scattering Model for Conducting Randomly Rough Surface

    Institute of Scientific and Technical Information of China (English)

    刘宁; 李宗谦

    2002-01-01

    A scattering model is developed to predict the scattering coefficient of a conducting randomly rough surface by analyzing the randomly rough surface in the spectral domain using the bi-spectrum method. For common randomly rough surfaces without obvious two-scale characteristics, a scale-compression filter can divide the auto-correlation spectrum into two parts with different correlation lengths. The Kirchhoff approximation and the small perturbation method are used to obtain the surface field, then a bistatic scattering model, the bi-spectrum model (BSM), is used to derive an explicit expression from the surface field. Examples using the integral equation model (IEM), finite difference of the time domain (FDTD) method, and BSM show that the BSM accuracy is acceptable and its range of validity is similar to IEM. BSM can also be extended to a scattering model for dielectric randomly rough surfaces.

  5. Ultralow Friction with Hydrophilic Polymer Brushes in Water as Segregated from Silicone Matrix

    DEFF Research Database (Denmark)

    Røn, Troels; Javakhishvili, Irakli; Hvilsted, Søren

    2015-01-01

    Lubrication is essential to minimize damage to underlying material and ensure low energy dissipation in biological and man-made mechanical sys- tems. Surface grafting of hydrophilic polymer brushes is a powerful means to render materials that are slippery in aqueous environments. However, present...

  6. Modeling surface growth of Escherichia coli on agar plates.

    Science.gov (United States)

    Fujikawa, Hiroshi; Morozumi, Satoshi

    2005-12-01

    Surface growth of Escherichia coli cells on a membrane filter placed on a nutrient agar plate under various conditions was studied with a mathematical model. The surface growth of bacterial cells showed a sigmoidal curve with time on a semilogarithmic plot. To describe it, a new logistic model that we presented earlier (H. Fujikawa et al., Food Microbiol. 21:501-509, 2004) was modified. Growth curves at various constant temperatures (10 to 34 degrees C) were successfully described with the modified model (model III). Model III gave better predictions of the rate constant of growth and the lag period than a modified Gompertz model and the Baranyi model. Using the parameter values of model III at the constant temperatures, surface growth at various temperatures was successfully predicted. Surface growth curves at various initial cell numbers were also sigmoidal and converged to the same maximum cell numbers at the stationary phase. Surface growth curves at various nutrient levels were also sigmoidal. The maximum cell number and the rate of growth were lower as the nutrient level decreased. The surface growth curve was the same as that in a liquid, except for the large curvature at the deceleration period. These curves were also well described with model III. The pattern of increase in the ATP content of cells grown on a surface was sigmoidal, similar to that for cell growth. We discovered several characteristics of the surface growth of bacterial cells under various growth conditions and examined the applicability of our model to describe these growth curves.

  7. Unusual properties of water at hydrophilic/hydrophobic interfaces.

    Science.gov (United States)

    Gun'ko, V M; Turov, V V; Bogatyrev, V M; Zarko, V I; Leboda, R; Goncharuk, E V; Novza, A A; Turov, A V; Chuiko, A A

    2005-12-30

    The behaviour of water at mosaic hydrophilic/hydrophobic surfaces of different silicas and in biosystems (biomacromolecules, yeast cells, wheat seeds, bone and muscular tissues) was studied in different dispersion media over wide temperature range using 1H NMR spectroscopy with layer-by-layer freezing-out of bulk water (close to 273 K) and interfacial water (180 water and water bound to hydrophilic/hydrophobic interfaces can be assigned to different structural types. There are (i) weakly associated interfacial water (1H NMR chemical shift delta(H) = 1.1-1.7 ppm) that can be assigned to high-density water (HDW) with collapsed structure (CS), representing individual molecules in hydrophobic pockets, small clusters and interstitial water with strongly distorted hydrogen bonds or without them, and (ii) strongly associated interfacial water (delta(H) = 4-5 ppm) with larger clusters, nano- and microdomains, and continuous interfacial layer with both HDW and low-density water (LDW). The molecular mobility of weakly associated bound water is higher (because hydrogen bonds are distorted and weakened and their number is smaller than that for strongly associated water) than that of strongly associated bound water (with strong hydrogen bonds but nevertheless weaker than that in ice Ih) that results in the difference in the temperature dependences of the 1H NMR spectra at T waters are also appear in changes in the IR and TSDC spectra.

  8. Intelligent hydrophilic nanoparticles fabricated via alkaline hydrolysis of crosslinked polyacrylonitrile nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Y., E-mail: zhyw@dhu.edu.cn; Wu, Q.; Zhang, H.; Zhao, J. [Donghua University, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Material Science and Engineering, Chemical Fibers Research Institute (China)

    2013-07-15

    Crosslinked polyacrylonitrile (PAN) nanolatex, with an average hydrodynamic diameter of 84 nm and a polydispersity index of 0.06, was successfully synthesized at a high monomer concentration and low surfactant content via a modified emulsion polymerization. Three measurements were adopted to control the nucleation and growth processes. Taking advantage of the chemical activity of nitrile groups, intelligent hydrophilic polymeric nanoparticles were fabricated via simple alkaline hydrolysis treatment of the crosslinked PAN nanolatex. Dynamic light scattering, electrophoretic light scattering, FT-IR spectroscopy, elemental analysis, and TEM observations were used to monitor the changes in the composition, structure, and morphology of the nanoparticles during the hydrolysis process. The sizes, chemical composition, morphology, and pH-responsive behavior of the intelligent hydrophilic nanoparticles could be adjusted by simply changing the hydrolysis time. As the hydrolysis was prolonged, the following nanoparticles could be obtained, crosslinked PAN nanoparticles with hydrophilic surfaces, amphiphilic nanoparticles with a hydrophobic PAN core and a hydrophilic polymeric shell composed of acrylamide and acrylic acid units, or carboxylic polyacrylamide nanoparticles. These modified nanoparticles all display good hydrophilicity, good biocompatibility, pH-sensitivity, as well as carboxyl functional groups, and thus are ideal candidates for various biomedical applications.

  9. Modeling Characteristics Of Surfaces For Radar Polarimetry

    Science.gov (United States)

    Van Zyl, Jakob J.; Zebker, Howard A.; Durden, Stephen L.

    1992-01-01

    Paper reviews mathematical models of polarimetric radar backscattering characteristics of various types of terrain; forests, grasslands, and lava fields. Represents approach to imaging radar polarimetry in which one accumulates models predicting realistic polarization signatures and represent distinct scattering processes, without attempting full vector solutions of Maxwell's equations in all cases. Idea to develop ability to invert models to identify unknown terrain depicted in polarimetric radar images. Describes models, major scattering characteristics predicted by models, and interpretation of characteristics in terms of dominant scattering mechanisms. Models predict realistic polarization signatures.

  10. Modeling And Analysis Of The Surface Roughness And Geometrical Error Using Taguchi And Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    DR.S.C.JAYSWAL

    2011-07-01

    Full Text Available This experimental work presents a technique to determine the better surface quality by controlling the surface roughness and geometrical error. In machining operations, achieving desired surface quality features of the machined product is really a challenging job. Because, these quality features are highly correlated and areexpected to be influenced directly or indirectly by the direct effect of process parameters or their interactive effects. Thus The four input process parameters such as spindle speed, depth of cut, feed rate, and stepover have been selected to minimize the surface roughness and geometrical error simultaneously by using the robustdesign concept of Taguchi L9(34 method coupled with Response surface concept. Mathematical models for surface roughness and geometrical error were obtained from response surface analysis to predict values of surface roughness and geometrical error. S/N ratio and ANOVA analyses were also performed to obtain for significant parameters influencing surface roughness and geometrical error.

  11. Preparation and Characterization of Hydrophilically Modified PVDF Membranes by a Novel Nonsolvent Thermally Induced Phase Separation Method

    Directory of Open Access Journals (Sweden)

    Ningen Hu

    2016-11-01

    Full Text Available In this study, a nonsolvent thermally-induced phase separation (NTIPS method was first proposed to fabricate hydrophilically-modified poly(vinylidene fluoride (PVDF membranes to overcome the drawbacks of conventional thermally-induced phase separation (TIPS and nonsolvent-induced phase separation (NIPS methods. Hydrophilically-modified PVDF membranes were successfully prepared by blending in hydrophilic polymer polyvinyl alcohol (PVA at 140 °C. A series of PVDF/PVA blend membranes was prepared at different total polymer concentrations and blend ratios. The morphological analysis via SEM indicated that the formation mechanism of these hydrophilically-modified membranes was a combined NIPS and TIPS process. As the total polymer concentration increased, the tensile strength of the membranes increased; meanwhile, the membrane pore size, porosity and water flux decreased. With the PVDF/PVA blend ratio increased from 10:0 to 8:2, the membrane pore size and water flux increased. The dynamic water contact angle of these membranes showed that the hydrophilic properties of PVDF/PVA blend membranes were prominently improved. The higher hydrophilicity of the membranes resulted in reduced membrane resistance and, hence, higher permeability. The total resistance Rt of the modified PVDF membranes decreased significantly as the hydrophilicity increased. The irreversible fouling related to pore blocking and adsorption fouling onto the membrane surface was minimal, indicating good antifouling properties.

  12. Development of hydrophilic dental wax without surfactant using a non-thermal air atmospheric pressure plasma jet

    Science.gov (United States)

    Lee, Jung-Hwan; Kim, Yong-Hee; Choi, Eun-Ha; Kim, Kwang-Mahn; Kim, Kyoung-Nam

    2014-06-01

    Dental wax (DW), a low-melting and high-molecular-weight organic mixture, is widely used in dentistry for forming moulds of teeth. Hydrophilicity is an important property for DW, as a wet dental investment is used to surround the wax before wax burnout is performed. However, recent attempts to improve the hydrophilicity of DW using a surfactant have resulted in the reduced mechanical properties of the dental investment, leading to the failure of the dental restoration. This study applied a non-thermal air atmospheric pressure plasma jet (AAPPJ) for DW surface treatment and investigated its effect on both DW hydrophilicity and the dental investment's mechanical properties. The results showed that the application of the AAPPJ significantly improved the hydrophilicity of the DW, and that the results were similar to that of cleaner-treated DW using commercially available products with surfactant. A surface chemical analysis indicated that the improvement of hydrophilicity was related to an increase in the number of oxygen-related bonds on the DW surface following the removal of carbon hydrate in both AAPPJ and cleaner-treated DW. However, cleaner treatment compromised the mechanical property of the dental investment when the dental investment was in contact with the treated DW, while the AAPPJ treatment did not. Therefore, the use of AAPPJ to treat DW is a promising method for accurate dental restoration, as it induces an improvement in hydrophilicity without harming the dental investment.

  13. Surface Self-Assembly and Properties of Monolayers Formed by Reverse Poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) Triblock Copolymers with Lengthy Hydrophilic Blocks

    DEFF Research Database (Denmark)

    Villar-Alvarez, Eva; Freire, Adriana Cambón; Blanco, Mateo

    2017-01-01

    The surface behavior and properties of several reverse poly(butylene oxide)-poly(ethylene oxide)-poly(butylene oxide) block copolymers, BO8EO90BO8, BO12EO227BO12, BO14EO378BO14, BO20EO411BO20, and BO21EO385BO21 at the air/water interface have been analyzed by drop tensiometry, Langmuir film balance...

  14. Modelling Catalyst Surfaces Using DFT Cluster Calculations

    Directory of Open Access Journals (Sweden)

    Oliver Kröcher

    2009-09-01

    Full Text Available We review our recent theoretical DFT cluster studies of a variety of industrially relevant catalysts such as TiO2, γ-Al2O3, V2O5-WO3-TiO2 and Ni/Al2O3. Aspects of the metal oxide surface structure and the stability and structure of metal clusters on the support are discussed as well as the reactivity of surfaces, including their behaviour upon poisoning. It is exemplarily demonstrated how such theoretical considerations can be combined with DRIFT and XPS results from experimental studies.

  15. Modelling catalyst surfaces using DFT cluster calculations.

    Science.gov (United States)

    Czekaj, Izabela; Wambach, Jörg; Kröcher, Oliver

    2009-11-20

    We review our recent theoretical DFT cluster studies of a variety of industrially relevant catalysts such as TiO(2), gamma-Al(2)O(3), V(2)O(5)-WO(3)-TiO(2) and Ni/Al(2)O(3). Aspects of the metal oxide surface structure and the stability and structure of metal clusters on the support are discussed as well as the reactivity of surfaces, including their behaviour upon poisoning. It is exemplarily demonstrated how such theoretical considerations can be combined with DRIFT and XPS results from experimental studies.

  16. A TECHNIQUE OF DIGITAL SURFACE MODEL GENERATION

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    It is usually a time-consuming process to real-time set up 3D digital surface mo del(DSM) of an object with complex sur face.On the basis of the architectural survey proje ct of“Chilin Nunnery Reconstruction",this paper investigates an easy and feasi ble way,that is,on project site,applying digital close range photogrammetry an d CAD technique to establish the DSM for simulating ancient architectures with c omplex surface.The method has been proved very effective in practice.

  17. Methanol Oxidation on Model Elemental and Bimetallic Transition Metal Surfaces

    DEFF Research Database (Denmark)

    Tritsaris, G. A.; Rossmeisl, J.

    2012-01-01

    Direct methanol fuel cells are a key enabling technology for clean energy conversion. Using density functional theory calculations, we study the methanol oxidation reaction on model electrodes. We discuss trends in reactivity for a set of monometallic and bimetallic transition metal surfaces, flat...... sites on the surface and to screen for novel bimetallic surfaces of enhanced activity. We suggest platinum copper surfaces as promising anode catalysts for direct methanol fuel cells....

  18. Emissivity as a Function of Surface Roughness: A Computer Model.

    Science.gov (United States)

    1986-08-29

    dependance on surface roughness sheds some light on ship wake measurements (8] , and corrects some of the analysis of spatial sea surface temperature...variation recently reported in (6) . The wind wave spectral dependance of surface emissivity also indicates that shorter wavelengths, such as...definition, a power spectrum contains no phase dependance . Therefore, in order to create a reasonable model of the surface elevation, we assume that the

  19. Radiative Transfer Model for Contaminated Rough Surfaces

    Science.gov (United States)

    2013-02-01

    plot of Figure 8 shows three sharp spectral features (in the LWIR region) that were used for calibration . 1000 1500 2000 2500 3000 3500 0 0.1 0.2...transfer, reflectance, rough surface, BRDF, Kramers-Kronig, penetration depth, fill factor, infrared, LWIR , MWIR, absorption coefficient, scattering...and the calibrated α are plotted in red, and green, respectively

  20. Modelling Surface Finish in WEDM using RSM

    Directory of Open Access Journals (Sweden)

    Amit Joshi

    2013-12-01

    Full Text Available Wire electrical discharge machining (WEDM is a specialized thermal machining process capable of accurately machining parts with varying hardness or complex shapes, which have sharp edges that are very difficult to be machined by the conventional machining processes. This practical technology of the WEDM process is based on the conventional EDM sparking phenomenon utilizing the widely accepted non-contact technique of material removal. Since the introduction of the process, WEDM has evolved from a simple means of making tools and dies to the best alternative of producing micro-scale parts with the highest degree of dimensional accuracy and surface finish quality. The effect of various parameters of WEDM like pulse on time (TON, pulse off time (TOFF, gap voltage (SV have been investigated to reveal their impact on output parameter i.e., surface roughness of high carbon and high chromium steel using response surface methodology. Experimental plan is performed by standard RSM design called a BOX-BEHKEN DESIGN. The optimal set of process parameter has also been predicted to maximize the surface finish.

  1. Enhanced Hydrophilicity and Biocompatibility of Dental Zirconia Ceramics by Oxygen Plasma Treatment

    Directory of Open Access Journals (Sweden)

    Ching-Chou Wu

    2015-02-01

    Full Text Available Surface properties play a critical role in influencing cell responses to a biomaterial. The objectives of this study were (1 to characterize changes in surface properties of zirconia (ZrO2 ceramic after oxygen plasma treatment; and (2 to determine the effect of such changes on biological responses of human osteoblast-like cells (MG63. The results indicated that the surface morphology was not changed by oxygen plasma treatment. In contrast, oxygen plasma treatment to ZrO2 not only resulted in an increase in hydrophilicity, but also it retained surface hydrophilicity after 5-min treatment time. More importantly, surface properties of ZrO2 modified by oxygen plasma treatment were beneficial for cell growth, whereas the surface roughness of the materials did not have a significant efficacy. It is concluded that oxygen plasma treatment was certified to be effective in modifying the surface state of ZrO2 and has the potential in the creation and maintenance of hydrophilic surfaces and the enhancement of cell proliferation and differentiation.

  2. Model for the Evolving Bed Surface around an Offshore Monopile

    DEFF Research Database (Denmark)

    Hartvig, Peres Akrawi

    2012-01-01

    This paper presents a model for the bed surface around an offshore monopile. The model has been designed from measured laboratory bed surfaces and is shown to reproduce these satisfactorily for both scouring and backfilling. The local rate of the bed elevation is assumed to satisfy a certain gene...

  3. A scattering model for surface-textured thin films

    NARCIS (Netherlands)

    Jäger, K.; Zeman, M.

    2009-01-01

    We present a mathematical model that relates the surface morphology of randomly surface-textured thin films with the intensity distribution of scattered light. The model is based on the first order Born approximation [see e.g., M. Born and E. Wolf, Principles of Optics, 7th ed. (Cambridge University

  4. A scattering model for surface-textured thin films

    NARCIS (Netherlands)

    Jäger, K.; Zeman, M.

    2009-01-01

    We present a mathematical model that relates the surface morphology of randomly surface-textured thin films with the intensity distribution of scattered light. The model is based on the first order Born approximation [see e.g., M. Born and E. Wolf, Principles of Optics, 7th ed. (Cambridge University

  5. Modeling wind adjustment factor and midflame wind speed for Rothermel's surface fire spread model

    Science.gov (United States)

    Patricia L. Andrews

    2012-01-01

    Rothermel's surface fire spread model was developed to use a value for the wind speed that affects surface fire, called midflame wind speed. Models have been developed to adjust 20-ft wind speed to midflame wind speed for sheltered and unsheltered surface fuel. In this report, Wind Adjustment Factor (WAF) model equations are given, and the BehavePlus fire modeling...

  6. Heterojunction of hydrophobic poly(1,4-phenylenevinylene) and hydrophilic PEDOT:PSS on hydrophilic CdS nanoparticles.

    Science.gov (United States)

    Lee, Wonjoo; Baek, Su Jin; Min, Sun Ki; Cai, Gangri; Lee, Joong Ki; Cho, Byung Won; Lee, Soo-Hyoung; Han, Sung-Hwan

    2008-09-01

    Heterojunction of hydrophobic poly(1,4-phenylenevinylene) (PPV) on hydrophilic CdS nanoparticles was successfully prepared by the multi-layering of poly(p-xylene tetrahydrothiophenium chloride) (pre-PPV: precursor of PPV polymer) and poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS) in an aqueous solution followed by a thermal treatment. CdS nanoparticles thin films were prepared on tin-doped indium oxide (ITO) by a chemical-bath-deposition method. The CdS surface was hydrophilic with low water contact angle of 15 degrees. Positively charged and water-soluble pre-PPV was used to form multilayers with PEDOT:PSS by a layer-by-layer deposition method. Pre-PPV is easily converted to conjugated PPV polymer by a thermal treatment. The CdS nanoparticles-(PPV/PEDOT:PSS) multilayer films constitute efficient acceptor-sensitizer dyad systems, which generate a photocurrent of 2,660 nA/cm2 under the air mass (AM) 1.5 conditions (I=100 mW/cm2) for sample with 4.5 bilayers.

  7. Revisiting the global surface energy budgets with maximum-entropy-production model of surface heat fluxes

    Science.gov (United States)

    Huang, Shih-Yu; Deng, Yi; Wang, Jingfeng

    2016-10-01

    The maximum-entropy-production (MEP) model of surface heat fluxes, based on contemporary non-equilibrium thermodynamics, information theory, and atmospheric turbulence theory, is used to re-estimate the global surface heat fluxes. The MEP model predicted surface fluxes automatically balance the surface energy budgets at all time and space scales without the explicit use of near-surface temperature and moisture gradient, wind speed and surface roughness data. The new MEP-based global annual mean fluxes over the land surface, using input data of surface radiation, temperature data from National Aeronautics and Space Administration-Clouds and the Earth's Radiant Energy System (NASA CERES) supplemented by surface specific humidity data from the Modern-Era Retrospective Analysis for Research and Applications (MERRA), agree closely with previous estimates. The new estimate of ocean evaporation, not using the MERRA reanalysis data as model inputs, is lower than previous estimates, while the new estimate of ocean sensible heat flux is higher than previously reported. The MEP model also produces the first global map of ocean surface heat flux that is not available from existing global reanalysis products.

  8. Revisiting the global surface energy budgets with maximum-entropy-production model of surface heat fluxes

    Science.gov (United States)

    Huang, Shih-Yu; Deng, Yi; Wang, Jingfeng

    2017-09-01

    The maximum-entropy-production (MEP) model of surface heat fluxes, based on contemporary non-equilibrium thermodynamics, information theory, and atmospheric turbulence theory, is used to re-estimate the global surface heat fluxes. The MEP model predicted surface fluxes automatically balance the surface energy budgets at all time and space scales without the explicit use of near-surface temperature and moisture gradient, wind speed and surface roughness data. The new MEP-based global annual mean fluxes over the land surface, using input data of surface radiation, temperature data from National Aeronautics and Space Administration-Clouds and the Earth's Radiant Energy System (NASA CERES) supplemented by surface specific humidity data from the Modern-Era Retrospective Analysis for Research and Applications (MERRA), agree closely with previous estimates. The new estimate of ocean evaporation, not using the MERRA reanalysis data as model inputs, is lower than previous estimates, while the new estimate of ocean sensible heat flux is higher than previously reported. The MEP model also produces the first global map of ocean surface heat flux that is not available from existing global reanalysis products.

  9. Microcavity-array superhydrophobic surfaces: Limits of the model

    Science.gov (United States)

    Salvadori, M. C.; Oliveira, M. R. S.; Spirin, R.; Teixeira, F. S.; Cattani, M.; Brown, I. G.

    2013-11-01

    Superhydrophobic surfaces formed of microcavities can be designed with specific desired advancing and receding contact angles using a new model described by us in prior work. Here, we discuss the limits of validity of the model, and explore the application of the model to surfaces fabricated with small cavities of radius 250 nm and with large cavities of radius 40 μm. The Wenzel model is discussed and used to calculate the advancing and receding contact angles for samples for which our model cannot be applied. We also consider the case of immersion of a sample containing microcavities in pressurized water. A consideration that then arises is that the air inside the cavities can be dissolved in the water, leading to complete water invasion into the cavities and compromising the superhydrophobic character of the surface. Here, we show that this effect does not destroy the surface hydrophobia when the surface is subsequently removed from the water.

  10. Biodegradable hydrophobic-hydrophilic hybrid hydrogels: swelling behavior and controlled drug release.

    Science.gov (United States)

    Wu, Da-Qing; Chu, Chih-Chang

    2008-01-01

    The objective of this work was to investigate a new family of hydrophobic-hydrophilic biodegradable hybrid hydrogels as drug carriers. A series of hydrophobic-hydrophilic biodegradable hybrid hydrogels was formulated via photo means from hydrophobic three-arm poly (epsilon-caprolactone) maleic acid (PGCL-Ma) and hydrophilic dextran maleic acid (Dex-Ma) precursors over a wide range of the two precursors' feed ratio (PGCL-Ma/Dex-Ma at 100:0, 70:30, 50:50, 30:70 and 0:100). A low-molecular-weight and hydrophilic drug, the alpha-7 agonist cocaine methiodide, was used as the model drug for the release study from the hybrid hydrogels in pH 7.4 phosphate buffer solution at 37 degrees C. The swelling data of these hybrid hydrogels depended on the hydrophobic to hydrophilic precursors' feed ratio, and there were several-fold differences in swelling ratios between a pure hydrophilic Dex-Ma and a pure hydrophobic PGCL-Ma hydrogels. The presence of the hydrophobic PGCL-Ma component significantly reduced the initial burst swelling of the hybrid hydrogels. Depending on the two precursors' feed ratios, the swelling data during the early period obeyed either Fickian diffusion (for 50:50 PGCL-Ma/Dex-Ma hydrogel), non-Fickian or anomalous transport (for 70:30 and 100:0 PGCL-Ma/Dex-Ma), or relaxation-controlled (for 30:70 and 0:100 PGCL-Ma/Dex-Ma). A wide range of cocaine methiodide release profiles was achieved by controlling hydrophobic to hydrophilic precursors' feed ratios. Initial drug burst release was significantly reduced as the concentration of the hydrophobic PGCL-Ma component increased in the hybrid hydrogels. The bulk of cocaine methiodide released during the 160-h period was via diffusion-controlled mechanism, while degradation-controlled mechanism dominated thereafter.

  11. Effect of hydrophilic walls on the hydration of sodium cations in planar nanopores

    Science.gov (United States)

    Shevkunov, S. V.

    2016-09-01

    A computer simulation of the structure of Na+ ion hydration shells with sizes in the range of 1 to 100 molecules in a planar model nanopore 0.7 nm wide with structureless hydrophilic walls is performed using the Monte Carlo method at a temperature of 298 K. A detailed model of many-body intermolecular interactions, calibrated with reference to experimental data on the free energy and enthalpy of reactions after gaseous water molecules are added to a hydration shell, is used. It is found that perturbations produced by hydrophilic walls cause the hydration shell to decay into two components that differ in their spatial arrangement and molecular orientational order.

  12. SSM - SOLID SURFACE MODELER, VERSION 6.0

    Science.gov (United States)

    Goza, S. P.

    1994-01-01

    The Solid Surface Modeler (SSM) is an interactive graphics software application for solid-shaded and wireframe three- dimensional geometric modeling. It enables the user to construct models of real-world objects as simple as boxes or as complex as Space Station Freedom. The program has a versatile user interface that, in many cases, allows mouse input for intuitive operation or keyboard input when accuracy is critical. SSM can be used as a stand-alone model generation and display program and offers high-fidelity still image rendering. Models created in SSM can also be loaded into other software for animation or engineering simulation. (See the information below for the availability of SSM with the Object Orientation Manipulator program, OOM, a graphics software application for three-dimensional rendering and animation.) Models are constructed within SSM using functions of the Create Menu to create, combine, and manipulate basic geometric building blocks called primitives. Among the simpler primitives are boxes, spheres, ellipsoids, cylinders, and plates; among the more complex primitives are tubes, skinned-surface models and surfaces of revolution. SSM also provides several methods for duplicating models. Constructive Solid Geometry (CSG) is one of the most powerful model manipulation tools provided by SSM. The CSG operations implemented in SSM are union, subtraction and intersection. SSM allows the user to transform primitives with respect to each axis, transform the camera (the user's viewpoint) about its origin, apply texture maps and bump maps to model surfaces, and define color properties; to select and combine surface-fill attributes, including wireframe, constant, and smooth; and to specify models' points of origin (the positions about which they rotate). SSM uses Euler angle transformations for calculating the results of translation and rotation operations. The user has complete control over the modeling environment from within the system. A variety of file

  13. Chirality on Surfaces: Modeling and Behaviour.

    Energy Technology Data Exchange (ETDEWEB)

    Paci, Irina; Szleifer, Igal; Ratner, Mark A.

    2007-09-01

    The research described in this product was performed in part in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory. Chirality has been a fascinating topic in chemistry, ever since its first observation by Biot in 1815. Its molecular basis was first understood by Pasteur in 1848. Enantiomers, identical in every way but mirror-images of each other, have similar physical properties, behave identically in chemical reactions with achiral molecules, but have very different interactions with chiral molecules. In recent decades, chirality has become an important direction in pharmaceutical research, as many drugs have stereoselective activity. This review focuses on a new aspect of chiral resolution on solid surfaces, and relationships between molecular structure, thermodynamic effects, and the result of chiral surface self-organization.

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

    Science.gov (United States)

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

    1982-01-01

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

  15. Study on the removal of organic micropollutants from aqueous and ethanol solutions by HAP membranes with tunable hydrophilicity and hydrophobicity.

    Science.gov (United States)

    He, Junyong; Li, Yulian; Cai, Xingguo; Chen, Kai; Zheng, Hejing; Wang, Chengming; Zhang, Kaisheng; Lin, Dongyue; Kong, Lingtao; Liu, Jinhuai

    2017-05-01

    A biocompatible and uniquely defined hydroxyapatite (HAP) adsorption membrane with a sandwich structure was developed for the removal of organic micropollutants for the first time. Both the adsorption and membrane technique were used for the removal of organic micropollutants. The hydrophilicity and hydrophobicity of the HAP adsorbent and membrane were tunable by controlling the surface structure of HAP. The adsorption of organic micropollutants on the HAP adsorbent was studied in batch experiments. The adsorption process was fit with the Freundlich model, while the adsorption kinetics followed the pseudo-second-order model. The HAP membrane could remove organic micropollutants effectively by dynamic adsorption in both aqueous and ethanol solutions. The removal efficiencies of organic micropollutants depended on the solution composition, membrane thickness and hydrophilicity, flow rate, and the initial concentration of organic micropollutants. The adsorption capacities of the HAP membrane with a sandwich structure (membrane thickness was 0.3 mm) were 6700, 6510, 6310, 5960, 5490, 5230, 4980 and 4360 L m(-2) for 1-naphthyl amine, 2-naphthol, bisphenol S, propranolol hydrochloride, metolachlor, ethinyl oestradiol, 2,4-dichlorophenol and bisphenol A, respectively, when the initial concentration was 3.0 mg L(-1). The biocompatible HAP adsorption membrane can be easily regenerated by methanol and was thus demonstrated to be a novel concept for the removal of organic micropollutants from both aqueous and organic solutions.

  16. Evaluation of models to predict insolation on tilted surfaces

    Science.gov (United States)

    Klucher, T. M.

    1979-01-01

    An empirical study was performed to evaluate the validity of various insolation models which employ either an isotropic or an anisotropic distribution approximation for sky light when predicting insolation on tilted surfaces. Data sets of measured hourly insolation values were obtained over a 6-month period using pyranometers which received diffuse and total solar radiation on a horizontal plane and total radiation on surfaces tilted toward the equator at 37 degrees and 60 degrees angles above the horizon. Data on the horizontal surfaces were used in the insolation models to predict insolation on the tilted surface; comparisons of measured vs calculated insolation on the tilted surface were examined to test the validity of the sky light approximations. It was found that the Liu-Jordan isotropic distribution model provides a good fit to empirical data under overcast skies but underestimates the amount of solar radiation incident on tilted surfaces under clear and partly cloudy conditions.

  17. Modeling noncontact atomic force microscopy resolution on corrugated surfaces

    Directory of Open Access Journals (Sweden)

    Kristen M. Burson

    2012-03-01

    Full Text Available Key developments in NC-AFM have generally involved atomically flat crystalline surfaces. However, many surfaces of technological interest are not atomically flat. We discuss the experimental difficulties in obtaining high-resolution images of rough surfaces, with amorphous SiO2 as a specific case. We develop a quasi-1-D minimal model for noncontact atomic force microscopy, based on van der Waals interactions between a spherical tip and the surface, explicitly accounting for the corrugated substrate (modeled as a sinusoid. The model results show an attenuation of the topographic contours by ~30% for tip distances within 5 Å of the surface. Results also indicate a deviation from the Hamaker force law for a sphere interacting with a flat surface.

  18. Long term hydrophilic coating on poly(dimethylsiloxane) substrates for microfluidic applications

    Energy Technology Data Exchange (ETDEWEB)

    Maheshwari, Nidhi [Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai (India); Centre for Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai (India); Kottantharayil, Anil [Centre for Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai (India); Kumar, Mahesh [Surface Physics and Nanostructures Group, National Physical Laboratory, New Delhi (India); Mukherji, Soumyo, E-mail: mukherji@iitb.ac.in [Department of Biosciences and Bioengineering, Indian Institute of Technology Bombay, Mumbai (India); Centre for Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai (India)

    2010-11-01

    Poly(dimethylsiloxane) (PDMS) has been used extensively for microfluidic components and as substrates for biological applications. Since the native nature of PDMS is hydrophobic it requires a functionalization step for use in conjunction with aqueous media. Commonly, oxygen plasma treatment is used for the formation of hydrophilic groups on the surface. However, the hydrophilic nature of these surfaces is short lived and the surfaces quickly revert back to their original hydrophobic state. In this work, branched-polyethylenimine (b-PEI) was used for long term modification of plasma treated PDMS surface. Contact angle, X-ray photoelectron spectroscopy (XPS) and Atomic force microscopy (AFM) were used for characterization of the modified surfaces and their stability with time was studied. The results obtained demonstrate that comparatively higher stability, hydrophilic, positively charged surfaces can be obtained after b-PEI treatment. These b-PEI treated PDMS surfaces can be used as fluidic channels for the separation of molecules as well as a substrate for the adherence of bio-molecules or biological cells.

  19. Surface-dependent chemical equilibrium constants and capacitances for bare and 3-cyanopropyldimethylchlorosilane coated silica nanochannels

    DEFF Research Database (Denmark)

    Andersen, Mathias Bækbo; Frey, Jared; Pennathur, Sumita

    2011-01-01

    We present a combined theoretical and experimental analysis of the solid–liquid interface of fused-silica nanofabricated channels with and without a hydrophilic 3-cyanopropyldimethylchlorosilane (cyanosilane) coating. We develop a model that relaxes the assumption that the surface parameters C1, C2...... filling length ratio on ionic strength for different surface compositions, which can be difficult to achieve otherwise....

  20. Drug release-modulating mechanism of hydrophilic hydroxypropylmethylcellulose matrix tablets: distribution of atoms and carrier and texture analysis.

    Science.gov (United States)

    Park, Jun-Bom; Lim, Jisung; Kang, Chin-Yang; Lee, Beom-Jin

    2013-12-01

    Although release profiles of drug from hydrophilic matrices have been well recognized, the visual distribution of hydroxypropylmethylcellulose (HPMC) and atoms inside of internal structures of hydrophilic HPMC matrices has not been characterized. In this paper, drug release mechanism from HPMC matrix tablet was investigated based on the release behaviors of HPMC, physical properties of gelled HPMC tablet and atomic distributions of formulation components using diverse instruments. A matrix tablet consisting of hydroxypropyl methylcellulose (HPMC 6, 4,000 and 100,000 mPa·s), chlorpheniramine maleate (CPM) as a model and fumed silicon dioxide (Aerosil(®) 200) was prepared via direct compression. The distribution of atoms and HPMC imaging were characterized using scanning electron microscope (SEM)/ energy-dispersive X-ray spectroscopy (EDX), and near-infrared (NIR) analysis, respectively as a function of time. A texture analyzer was also used to characterize the thickness and maintenance of gel layer of HPMC matrix tablet. The HPMC matrix tablets showed Higuchi release kinetics with no lag time against the square root of time. High viscosity grades of HPMC gave retarded release rate because of the greater swelling and gel thickness as characterized by texture analyzer. According to the NIR imaging, low-viscosity-grade HPMC (6 mPa·s) quickly leached out onto the surface of the tablet, while the high-viscosity-grade HPMC (4000 mPa·s) formed much thicker gel layer around the tablet and maintained longer via slow erosion, resulting in retarded drug release. The atomic distribution of the drug (chlorine, carbon, oxygen), HPMC (carbon, oxygen) and silicon dioxide (silica, oxygen) and NIR imaging of HPMC corresponded with the dissolution behaviors of drug as a function of time. The use of imaging and texture analyses could be applicable to explain the release- modulating mechanism of hydrophilic HPMC matrix tablets.

  1. Universal hydrophilic coating of thermoplastic polymers currently used in microfluidics.

    Science.gov (United States)

    Zilio, Caterina; Sola, Laura; Damin, Francesco; Faggioni, Lucia; Chiari, Marcella

    2014-02-01

    A number of materials used to fabricate disposable microfluidic devices are hydrophobic in nature with water contact angles on their surface ranging from 80° to over 100°. This characteristic makes them unsuitable for a number of microfluidic applications. Both the wettability and analyte adsorption parameters are highly dependent on the surface hydrophobicity. In this article, we propose a general method to coat the surface of five materials: polydimethylsiloxane (PDMS), cyclic olefin copolymer (COC), polyethylene terephthalate (PET), polycarbonate (PC), and polytetrafluoroethylene (PTFE). This fast and robust process, which is easily implementable in any laboratory including microfabrication clean room facilities, was devised by combining gas-phase and wet chemical modification processes. Two different coatings that improve the surface hydrophilicity were prepared via the "dip and rinse" approach by immersing the plasma oxidized materials into an aqueous solution of two different poly(dimethylacrylamide) copolymers incorporating a silane moiety and functionalized with either N-acryloyloxysuccinimide (NAS) (poly(DMA-NAS-MAPS) or glycidyl methacrylate (GMA) (poly(DMA-GMA-MAPS). The coating formation was confirmed by contact angle (CA) analysis comparing the variation of CAs of uncoated and coated surfaces subjected to different aging treatments. The antifouling character of the polymer was demonstrated by fluorescence and interferometric detection of proteins adsorbed on the surafce. This method is of great interest in microfluidics due to its broad applicability to a number of materials with varying chemical compositions.

  2. Towards a two dimensional model of surface piezoelectricity

    OpenAIRE

    Monge Víllora, Oscar

    2016-01-01

    We want to understand the behaviour of flexoelectricity and surface piezoelectricity and distinguish them in order to go deep into the controversies of the filed. This motivate the construction of a model of continuum flexoelectric theory. The model proposed is a two-dimensional model that integrates the electromechanical equations that include the elastic, dielectric, piezoelectric and flexoelectric effect on a rectangular sample. As the flexoelectric and the surface piezoelectric effects ap...

  3. Process analysis and optimization models defining recultivation surface mines

    Directory of Open Access Journals (Sweden)

    Dimitrijević Bojan V.

    2015-01-01

    Full Text Available Surface mines are generally open and very dynamic systems influenced by a large number of technical, economic, environmental and safety factors and limitations in all stages of the life cycle. In this paper the dynamic compliance period surface mining phases and of the reclamation. Also, an analysis of the reclamation of surface mines, and process flow management project recultivation is determined by the principled management model reclamation. The analysis of the planning process is defined by the model optimization recultivation surface mine.

  4. Separation of carbohydrates using hydrophilic interaction liquid chromatography.

    Science.gov (United States)

    Fu, Qing; Liang, Tu; Li, Zhenyu; Xu, Xiaoyong; Ke, Yanxiong; Jin, Yu; Liang, Xinmiao

    2013-09-20

    A strategy was developed to rapidly evaluate chromatographic properties of hydrophilic interaction chromatography (HILIC) columns for separating carbohydrates. Seven HILIC columns (Silica, Diol, TSK Amide-80, XAmide, Click Maltose, Click β-CD, and Click TE-Cys columns) were evaluated by using three monosaccharide and seven disaccharides as probes. The influence of column temperature on the peak shape and tautomerization of carbohydrates, as well as column selectivity were investigated. The influence of surface charge property on the retention was also studied by using glucose, glucuronic acid, and glucosamine, which indicated that buffer salt concentration and pH value in mobile phase was necessary to control the ionic interactions between ionic carbohydrates and HILIC columns. According to evaluation results, the XAmide column was selected as an example to establish experimental schemes for separation of complex mixtures of oligosaccharide.

  5. Kinetics of aqueous lubrication in the hydrophilic hydrogel Gemini interface.

    Science.gov (United States)

    Dunn, Alison C; Pitenis, Angela A; Urueña, Juan M; Schulze, Kyle D; Angelini, Thomas E; Sawyer, W Gregory

    2015-12-01

    The exquisite sliding interfaces in the human body share the common feature of hydrated dilute polymer mesh networks. These networks, especially when they constitute a sliding interface such as the pre-corneal tear film on the ocular interface, are described by the molecular weight of the polymer chains and a characteristic size of a minimum structural unit, the mesh size, ξ. In a Gemini interface where hydrophilic hydrogels are slid against each other, the aqueous lubrication behavior has been shown to be a function of sliding velocity, introducing a sliding timescale competing against the time scales of polymer fluctuation and relaxation at the surface. In this work, we examine two recent studies and postulate that when the Gemini interface slips faster than the single-chain relaxation time, chains must relax, suppressing the amplitude of the polymer chain thermal fluctuations.

  6. Response surface and artificial neural network prediction model and optimization for surface roughness in machining

    Directory of Open Access Journals (Sweden)

    Ashok Kumar Sahoo

    2015-04-01

    Full Text Available The present paper deals with the development of prediction model using response surface methodology and artificial neural network and optimizes the process parameter using 3D surface plot. The experiment has been conducted using coated carbide insert in machining AISI 1040 steel under dry environment. The coefficient of determination value for RSM model is found to be high (R2 = 0.99 close to unity. It indicates the goodness of fit for the model and high significance of the model. The percentage of error for RSM model is found to be only from -2.63 to 2.47. The maximum error between ANN model and experimental lies between -1.27 and 0.02 %, which is significantly less than the RSM model. Hence, both the proposed RSM and ANN prediction model sufficiently predict the surface roughness, accurately. However, ANN prediction model seems to be better compared with RSM model. From the 3D surface plots, the optimal parametric combination for the lowest surface roughness is d1-f1-v3 i.e. depth of cut of 0.1 mm, feed of 0.04 mm/rev and cutting speed of 260 m/min respectively.

  7. ENHANCED OIL RECOVERY BY FLOODING WITH HYDROPHILIC NANOPARTICLES

    Institute of Scientific and Technical Information of China (English)

    Binshan Ju; Tailiang Fan; Mingxue Ma

    2006-01-01

    In this paper, the mechanism of enhanced oil recovery using lipophobic and hydrophilic polysilicon (LHP)nanoparticles ranging in size from 10 to 500 nm for changing the wettability of porous media was analysed theoretically. A one-dimensional two-phase mathematical model considering the migration and adsorption of LHP and wettability change in reservoir rock was proposed, and a simulator was developed to quantitatively predict the changes in relative and effective permeability of the oil and water phases and the oil recovery in sandstone after water driving. Numerical simulations were conducted to study the distribution of the particle concentration, the reduction in porosity and absolute permeability, the LHP volume retention on pore walls and in pore throats along a dimensionless distance, and oil production performance. In conclusion, oil recovery can obviously be improved by flooding with hydrophilic nanometer powders though permeability declines for the retention of nanoparticles in porous media. It is suggested that an LHP concentration ranging from 0.02 to 0.03 is preferable to enhance oil recovery.

  8. Patterned gradient surface for spontaneous droplet transportation and water collection: simulation and experiment

    Science.gov (United States)

    Tan, Xianhua; Zhu, Yiying; Shi, Tielin; Tang, Zirong; Liao, Guanglan

    2016-11-01

    We demonstrate spontaneous droplet transportation and water collection on wedge-shaped gradient surfaces consisting of alternating hydrophilic and hydrophobic regions. Droplets on the surfaces are modeled and simulated to analyze the Gibbs free energy and free energy gradient distributions. Big half-apex angle and great wettability difference result in considerable free energy gradient, corresponding to large driving force for spontaneous droplet transportation, thus causing the droplets to move towards the open end of the wedge-shaped hydrophilic regions, where the Gibbs free energy is low. Gradient surfaces are then fabricated and tested. Filmwise condensation begins on the hydrophilic regions, forming wedge-shaped tracks for water collection. Dropwise condensation occurs on the hydrophobic regions, where the droplet size distribution and departure diameters are controlled by the width of the regions. Condensate water from both the hydrophilic and hydrophobic regions are collected directionally to the open end of the wedge-shaped hydrophilic regions, agreeing with the simulations. Directional droplet transport and controllable departure diameters make the branched gradient surfaces more efficient than smooth surfaces for water collection, which proves that gradient surfaces are potential in water collection, microfluidic devices, anti-fogging and self-cleaning.

  9. Numerical Study of Wind Turbine Wake Modeling Based on a Actuator Surface Model

    DEFF Research Database (Denmark)

    Zhou, Huai-yang; Xu, Chang; Han, Xing Xing

    2017-01-01

    In the Actuator Surface Model (ALM), the turbine blades are represented by porous surfaces of velocity and pressure discontinuities to model the action of lifting surfaces on the flow. The numerical simulation is implemented on FLUENT platform combined with N-S equations. This model is improved...

  10. Land Surface Microwave Emissivity Dynamics: Observations, Analysis and Modeling

    Science.gov (United States)

    Tian, Yudong; Peters-Lidard, Christa D.; Harrison, Kenneth W.; Kumar, Sujay; Ringerud, Sarah

    2014-01-01

    Land surface microwave emissivity affects remote sensing of both the atmosphere and the land surface. The dynamical behavior of microwave emissivity over a very diverse sample of land surface types is studied. With seven years of satellite measurements from AMSR-E, we identified various dynamical regimes of the land surface emission. In addition, we used two radiative transfer models (RTMs), the Community Radiative Transfer Model (CRTM) and the Community Microwave Emission Modeling Platform (CMEM), to simulate land surface emissivity dynamics. With both CRTM and CMEM coupled to NASA's Land Information System, global-scale land surface microwave emissivities were simulated for five years, and evaluated against AMSR-E observations. It is found that both models have successes and failures over various types of land surfaces. Among them, the desert shows the most consistent underestimates (by approx. 70-80%), due to limitations of the physical models used, and requires a revision in both systems. Other snow-free surface types exhibit various degrees of success and it is expected that parameter tuning can improve their performances.

  11. On the possibility of controlling the hydrophilic/hydrophobic characteristics of toroid Mo138 nanocluster polyoxometalates

    Science.gov (United States)

    Grzhegorzhevskii, K. V.; Adamova, L. V.; Eremina, E. V.; Ostroushko, A. A.

    2017-03-01

    The possibility of changing the hydrophilic (polar) surfaces of toroid nanocluster polyoxomolibdates to hydrophobic (nonpolar) surfaces via the modification of Mo138 nanoclusters by surfactant molecules (dodecylpyridinium chloride) as a result of the interaction between these compounds in solutions is demonstrated. Benzene and methanol are used as molecular probes (indicators of the condition of nanocluster surfaces). Comparative characteristics of the equilibrium sorption of benzene and methanol vapors on the initial and modified surfaces of the solid polyoxometalate, and data on the sorption of organic molecules on the surfaces of Rhodamine B-modified nanoclusters of the toroid (Mo138) and keplerate (Mo132) types are obtained.

  12. A Physically Based Transmission Model of Rough Surfaces

    Directory of Open Access Journals (Sweden)

    Yinlong Sun

    2008-11-01

    Full Text Available Transparent and translucent objects involve both light reflection and transmission at surfaces. This paper presents a physically based transmission model of rough surface. The surface is assumed to be locally smooth, and statistical techniques is applied to calculate light transmission through a local illumination area. We have obtained an analytical expression for single scattering. The analytical model has been compared to our Monte Carlo simulations as well as to the previous simulations, and good agreements have been achieved. The presented model has potential applications for realistic rendering of transparent and translucent objects.

  13. Real Time Land-Surface Hydrologic Modeling Over Continental US

    Science.gov (United States)

    Houser, Paul R.

    1998-01-01

    The land surface component of the hydrological cycle is fundamental to the overall functioning of the atmospheric and climate processes. Spatially and temporally variable rainfall and available energy, combined with land surface heterogeneity cause complex variations in all processes related to surface hydrology. The characterization of the spatial and temporal variability of water and energy cycles are critical to improve our understanding of land surface-atmosphere interaction and the impact of land surface processes on climate extremes. Because the accurate knowledge of these processes and their variability is important for climate predictions, most Numerical Weather Prediction (NWP) centers have incorporated land surface schemes in their models. However, errors in the NWP forcing accumulate in the surface and energy stores, leading to incorrect surface water and energy partitioning and related processes. This has motivated the NWP to impose ad hoc corrections to the land surface states to prevent this drift. A proposed methodology is to develop Land Data Assimilation schemes (LDAS), which are uncoupled models forced with observations, and not affected by NWP forcing biases. The proposed research is being implemented as a real time operation using an existing Surface Vegetation Atmosphere Transfer Scheme (SVATS) model at a 40 km degree resolution across the United States to evaluate these critical science questions. The model will be forced with real time output from numerical prediction models, satellite data, and radar precipitation measurements. Model parameters will be derived from the existing GIS vegetation and soil coverages. The model results will be aggregated to various scales to assess water and energy balances and these will be validated with various in-situ observations.

  14. Modeling Surface Roughness to Estimate Surface Moisture Using Radarsat-2 Quad Polarimetric SAR Data

    Science.gov (United States)

    Nurtyawan, R.; Saepuloh, A.; Budiharto, A.; Wikantika, K.

    2016-08-01

    Microwave backscattering from the earth's surface depends on several parameters such as surface roughness and dielectric constant of surface materials. The two parameters related to water content and porosity are crucial for estimating soil moisture. The soil moisture is an important parameter for ecological study and also a factor to maintain energy balance of land surface and atmosphere. Direct roughness measurements to a large area require extra time and cost. Heterogeneity roughness scale for some applications such as hydrology, climate, and ecology is a problem which could lead to inaccuracies of modeling. In this study, we modeled surface roughness using Radasat-2 quad Polarimetric Synthetic Aperture Radar (PolSAR) data. The statistical approaches to field roughness measurements were used to generate an appropriate roughness model. This modeling uses a physical SAR approach to predicts radar backscattering coefficient in the parameter of radar configuration (wavelength, polarization, and incidence angle) and soil parameters (surface roughness and dielectric constant). Surface roughness value is calculated using a modified Campbell and Shepard model in 1996. The modification was applied by incorporating the backscattering coefficient (σ°) of quad polarization HH, HV and VV. To obtain empirical surface roughness model from SAR backscattering intensity, we used forty-five sample points from field roughness measurements. We selected paddy field in Indramayu district, West Java, Indonesia as the study area. This area was selected due to intensive decreasing of rice productivity in the Northern Coast region of West Java. Third degree polynomial is the most suitable data fitting with coefficient of determination R2 and RMSE are about 0.82 and 1.18 cm, respectively. Therefore, this model is used as basis to generate the map of surface roughness.

  15. Fabrication, surface properties, and origin of superoleophobicity for a model textured surface.

    Science.gov (United States)

    Zhao, Hong; Law, Kock-Yee; Sambhy, Varun

    2011-05-17

    Inspired by the superhydrophobic effect displayed in nature, we set out to mimic the interplay between the chemistry and physics in the lotus leaf to see if the same design principle can be applied to control wetting and adhesion between toners and inks on various printing surfaces. Since toners and inks are organic materials, superoleophobicity has become our design target. In this work, we report the design and fabrication of a model superoleophobic surface on silicon wafer. The model surface was created by photolithography, consisting of texture made of arrays of ∼3 μm diameter pillars, ∼7 μm in height with a center-to-center spacing of 6 μm. The surface was then made oleophobic with a fluorosilane coating, FOTS, synthesized by the molecular vapor deposition technique with tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane. Contact angle measurement shows that the surface exhibits super repellency toward water and oil (hexadecane) with a water and hexadecane contact angles at 156° and 158°, respectively. Since the sliding angles for both liquids are also very small (∼10°), we conclude that the model surface is both superhydrophobic and superoleophobic. By comparing with the contact angle data of the bare silicon surfaces (both smooth and textured), we also conclude that the superoleophobicity is a result of both surface texturing and fluorination. Results from investigations of the effects of surface modification and pillar geometry indicate that both surface oleophobicity and pillar geometry are contributors to the superoleophobicity. More specifically, we found that superoleophobicity can only be attained on our model textured surface when the flat surface coating has a relatively high oleophobicity (i.e., with a hexadecane contact angle of >73°). SEM examination of the pillars with higher magnification reveals that the side wall in each pillar is not smooth; rather it consists of a ∼300 nm wavy structure (due to the Bosch etching process

  16. Exploring the effect of hydrophilic and hydrophobic structure of grafted polymeric micelles on drug loading.

    Science.gov (United States)

    Shi, Chenjun; Sun, Yujiao; Wu, Haiyang; Zhu, Chengyun; Wei, Guoguang; Li, Jinfeng; Chan, Tenglan; Ouyang, Defang; Mao, Shirui

    2016-10-15

    The objective of this paper is to explore the effect of hydrophilic and hydrophobic structure of grafted polymeric micelles on drug loading, and elucidate whether drug-polymer compatibility, as predicted by Hansen solubility parameters (HSPs), can be used as a tool for drug-polymer pairs screening and guide the design of grafted polymeric micelles. HSPs of 27 drugs and three grafted copolymers were calculated according to group contribution method. The drug-polymer compatibilities were evaluated using the approaches of Flory-Huggins interaction parameters (χFH) and polarity difference (△Xp). Two models, model A and B, were put forward for drug-polymer compatibility prediction. In model A, hydrophilic/hydrophobic part as a whole was regarded as one segment. And, in model B, hydrophilic and hydrophobic segments were evaluated individually. First of all, using chitosan (CS)-grafted-glyceryl monooeate (GMO) based micelle as an example, the suitability of model A and model B for predicating drug-polymer compatibility was evaluated theoretically. Thereafter, corresponding experiments were carried out to check the validity of the theoretical prediction. It was demonstrated that Model B, which evaluates drug compatibility with both hydrophilic and hydrophobic segments of the copolymer, is more reliable for drug-polymer compatibility prediction. Moreover, the approach of model B allows for the selection of a defined grafted polymer with for a specific drug and vice versa. Thus, drug compatibility evaluation via HSPs with both hydrophilic and hydrophobic segments is a suitable tool for the rational design of grafted polymeric micelles. The molecular dynamics (MD) simulation study provided further support to the established model and experimental results.

  17. Comparative Analysis of Uncertainties in Urban Surface Runoff Modelling

    DEFF Research Database (Denmark)

    Thorndahl, Søren; Schaarup-Jensen, Kjeld

    2007-01-01

    In the present paper a comparison between three different surface runoff models, in the numerical urban drainage tool MOUSE, is conducted. Analysing parameter uncertainty, it is shown that the models are very sensitive with regards to the choice of hydrological parameters, when combined overflow...... analysis, further research in improved parameter assessment for surface runoff models is needed....... volumes are compared - especially when the models are uncalibrated. The occurrences of flooding and surcharge are highly dependent on both hydrological and hydrodynamic parameters. Thus, the conclusion of the paper is that if the use of model simulations is to be a reliable tool for drainage system...

  18. MODELING THE INTERACTION OF AGROCHEMICALS WITH ENVIRONMENTAL SURFACES: PESTICIDES ON RUTILE AND ORGANO-RUTILE SURFACES

    Science.gov (United States)

    Non-bonded interactions between model pesticides and organo-mineral surfaces have been studied using molecular mechanical conformational calculations and molecular dynamics simulations. The minimum energy conformations and relative binding energies for the interaction of atrazine...

  19. A coarse grain model for protein-surface interactions

    Science.gov (United States)

    Wei, Shuai; Knotts, Thomas A.

    2013-09-01

    The interaction of proteins with surfaces is important in numerous applications in many fields—such as biotechnology, proteomics, sensors, and medicine—but fundamental understanding of how protein stability and structure are affected by surfaces remains incomplete. Over the last several years, molecular simulation using coarse grain models has yielded significant insights, but the formalisms used to represent the surface interactions have been rudimentary. We present a new model for protein surface interactions that incorporates the chemical specificity of both the surface and the residues comprising the protein in the context of a one-bead-per-residue, coarse grain approach that maintains computational efficiency. The model is parameterized against experimental adsorption energies for multiple model peptides on different types of surfaces. The validity of the model is established by its ability to quantitatively and qualitatively predict the free energy of adsorption and structural changes for multiple biologically-relevant proteins on different surfaces. The validation, done with proteins not used in parameterization, shows that the model produces remarkable agreement between simulation and experiment.

  20. EQUIVALENT NORMAL CURVATURE APPROACH MILLING MODEL OF MACHINING FREEFORM SURFACES

    Institute of Scientific and Technical Information of China (English)

    YI Xianzhong; MA Weiguo; QI Haiying; YAN Zesheng; GAO Deli

    2008-01-01

    A new milling methodology with the equivalent normal curvature milling model machining freeform surfaces is proposed based on the normal curvature theorems on differential geometry. Moreover, a specialized whirlwind milling tool and a 5-axis CNC horizontal milling machine are introduced. This new milling model can efficiently enlarge the material removal volume at the tip of the whirlwind milling tool and improve the producing capacity. The machining strategy of this model is to regulate the orientation of the whirlwind milling tool relatively to the principal directions of the workpiece surface at the point of contact, so as to create a full match with collision avoidance between the workpiece surface and the symmetric rotational surface of the milling tool. The practical results show that this new milling model is an effective method in machining complex three- dimensional surfaces. This model has a good improvement on finishing machining time and scallop height in machining the freeform surfaces over other milling processes. Some actual examples for manufacturing the freeform surfaces with this new model are given.

  1. Study on Dielectric Function Models for Surface Plasmon Resonance Structure

    Directory of Open Access Journals (Sweden)

    Peyman Jahanshahi

    2014-01-01

    Full Text Available The most common permittivity function models are compared and identifying the best model for further studies is desired. For this study, simulations using several different models and an analytical analysis on a practical surface Plasmon structure were done with an accuracy of ∼94.4% with respect to experimental data. Finite element method, combined with dielectric properties extracted from the Brendel-Bormann function model, was utilized, the latter being chosen from a comparative study on four available models.

  2. Hydrophilic, bactericidal nanoheater-enabled reverse osmosis membranes to improve fouling resistance.

    Science.gov (United States)

    Ray, Jessica R; Tadepalli, Sirimuvva; Nergiz, Saide Z; Liu, Keng-Ku; You, Le; Tang, Yinjie; Singamaneni, Srikanth; Jun, Young-Shin

    2015-06-03

    Polyamide (PA) semipermeable membranes typically used for reverse osmosis water treatment processes are prone to fouling, which reduces the amount and quality of water produced. By synergistically coupling the photothermal and bactericidal properties of graphene oxide (GO) nanosheets, gold nanostars (AuNS), and hydrophilic polyethylene glycol (PEG) on PA reverse osmosis membrane surfaces, we have dramatically improved fouling resistance of these membranes. Batch fouling experiments from three classes of fouling are presented: mineral scaling (CaCO3 and CaSO4), organic fouling (humic acid), and biofouling (Escherichia coli). Systematic analyses and a variety of complementary techniques were used to elucidate fouling resistance mechanisms from each layer of modification on the membrane surface. Both mineral scaling and organic fouling were significantly reduced in PA-GO-AuNS-PEG membranes compared to other membranes. The PA-GO-AuNS-PEG membrane was also effective in killing all near-surface bacteria compared to PA membranes. In the PA-GO-AuNS-PEG membrane, the GO nanosheets act as templates for in situ AuNS growth, which then facilitated localized heating upon irradiation by an 808 nm laser inactivating bacteria on the membrane surface. Furthermore, AuNS in the membrane assisted PEG in preventing mineral scaling on the membrane surface. In flow-through flux and foulant rejection tests, PA-GO-AuNS-PEG membranes performed better than PA membranes in the presence of CaSO4 and humic acid model foulants. Therefore, the newly suggested membrane surface modifications will not only reduce fouling from RO feeds, but can improve overall membrane performance. Our innovative membrane design reported in this study can significantly extend the lifetime and water treatment efficacy of reverse osmosis membranes to alleviate escalating global water shortage from rising energy demands.

  3. Hydrophilic PCU scaffolds prepared by grafting PEGMA and immobilizing gelatin to enhance cell adhesion and proliferation

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Changcan; Yuan, Wenjie; Khan, Musammir; Li, Qian [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Feng, Yakai, E-mail: yakaifeng@tju.edu.cn [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Key Laboratory of Systems Bioengineering of Ministry of Education, Tianjin University, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Tianjin 300072 (China); Collaborative Innovation Center of Chemical Science and Chemical Engineering (Tianjin) Tianjin 300072 (China); Yao, Fanglian [School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072 (China); Key Laboratory of Systems Bioengineering of Ministry of Education, Tianjin University, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Tianjin 300072 (China); Zhang, Wencheng, E-mail: wenchengzhang@yahoo.com [Department of Physiology and Pathophysiology, Logistics University of Chinese People' s Armed Police Force, Tianjin 300162 (China)

    2015-05-01

    Gelatin contains many functional motifs which can modulate cell specific adhesion, so we modified polycarbonate urethane (PCU) scaffold surface by immobilization of gelatin. PCU-g-gelatin scaffolds were prepared by direct immobilizing gelatins onto the surface of aminated PCU scaffolds. To increase the immobilization amount of gelatin, poly(ethylene glycol) methacrylate (PEGMA) was grafted onto PCU scaffolds by surface initiated atom transfer radical polymerization. Then, following amination and immobilization, PCU-g-PEGMA-g-gelatin scaffolds were obtained. Both modified scaffolds were characterized by chemical and biological methods. After immobilization of gelatin, the microfiber surface became rough, but the original morphology of scaffolds was maintained successfully. PCU-g-PEGMA-g-gelatin scaffolds were more hydrophilic than PCU-g-gelatin scaffolds. Because hydrophilic PEGMA and gelatin were grafted and immobilized onto the surface, the PCU-g-PEGMA-g-gelatin scaffolds showed low platelet adhesion, perfect anti-hemolytic activity and excellent cell growth and proliferation capacity. It could be envisioned that PCU-g-PEGMA-g-gelatin scaffolds might have potential applications in tissue engineering artificial scaffolds. - Graphical abstract: PCU-g-gelatin scaffolds were prepared by direct immobilizing gelatin onto the surface of aminated PCU scaffolds (method a). To increase the immobilization amount of gelatin, PEGMAs were grafted onto the scaffold surface by SI-ATRP. PCU-g-PEGMA-g-gelatin scaffolds were prepared by method b. The gelatin modified scaffolds exhibited high hydrophilicity, low platelet adhesion, perfect anti-hemolytic activity, and excellent cell adhesion and proliferation capacity. They might have potential applications as tissue engineering scaffolds for artificial blood vessels. - Highlights: • Hydrophilic scaffolds were prepared by grafting PEGMA and immobilization of gelatins. • Grafting PEGMA enhanced the immobilization amount of gelatin

  4. Adhesion to model surfaces in a flow through system

    Energy Technology Data Exchange (ETDEWEB)

    Habeger, C.F.; Linhart, R.V.; Adair, J.H. [Univ. of Florida, Gainesville, FL (United States)

    1995-12-31

    A hydrodynamic method for measuring the adhesion of particles to a surface has been designed. By using hydrodynamic flow to remove particles from a model surface, the adhesive strength of particles to the surface can be measured using a flow-through cell. The hydrodynamic force required to displace a particle is calculated using the cell dimensions and the flow rate in Poiseuille`s equation.

  5. Integrating Surface Modeling into the Engineering Design Graphics Curriculum

    Science.gov (United States)

    Hartman, Nathan W.

    2006-01-01

    It has been suggested there is a knowledge base that surrounds the use of 3D modeling within the engineering design process and correspondingly within engineering design graphics education. While solid modeling receives a great deal of attention and discussion relative to curriculum efforts, and rightly so, surface modeling is an equally viable 3D…

  6. Integrating Surface Modeling into the Engineering Design Graphics Curriculum

    Science.gov (United States)

    Hartman, Nathan W.

    2006-01-01

    It has been suggested there is a knowledge base that surrounds the use of 3D modeling within the engineering design process and correspondingly within engineering design graphics education. While solid modeling receives a great deal of attention and discussion relative to curriculum efforts, and rightly so, surface modeling is an equally viable 3D…

  7. Designing Superoleophobic Surfaces (Postprint)

    Science.gov (United States)

    2007-12-07

    recent experiments show that even the wax on the lotus leaf surface is weakly hydrophilic with q ≈ 74° (29). The superhydrophobic state of these...fibers (14), and spherical arrays of poly(tetrafluoroethylene) ( PTFE ) particles (17), as well as superhydrophobicity obtained on a hydrophilic substrate

  8. Hydration dynamics near a model protein surface

    Energy Technology Data Exchange (ETDEWEB)

    Russo, Daniela; Hura, Greg; Head-Gordon, Teresa

    2003-09-01

    The evolution of water dynamics from dilute to very high concentration solutions of a prototypical hydrophobic amino acid with its polar backbone, N-acetyl-leucine-methylamide (NALMA), is studied by quasi-elastic neutron scattering and molecular dynamics simulation for both the completely deuterated and completely hydrogenated leucine monomer. We observe several unexpected features in the dynamics of these biological solutions under ambient conditions. The NALMA dynamics shows evidence of de Gennes narrowing, an indication of coherent long timescale structural relaxation dynamics. The translational water dynamics are analyzed in a first approximation with a jump diffusion model. At the highest solute concentrations, the hydration water dynamics is significantly suppressed and characterized by a long residential time and a slow diffusion coefficient. The analysis of the more dilute concentration solutions takes into account the results of the 2.0M solution as a model of the first hydration shell. Subtracting the first hydration layer based on the 2.0M spectra, the translational diffusion dynamics is still suppressed, although the rotational relaxation time and residential time are converged to bulk-water values. Molecular dynamics analysis shows spatially heterogeneous dynamics at high concentration that becomes homogeneous at more dilute concentrations. We discuss the hydration dynamics results of this model protein system in the context of glassy systems, protein function, and protein-protein interfaces.

  9. Modeling of a nanoscale flexoelectric energy harvester with surface effects

    Science.gov (United States)

    Yan, Zhi

    2017-04-01

    This work presents the modeling of a beam energy harvester scavenging energy from ambient vibration based on the phenomenon of flexoelectricity. By considering surface elasticity, residual surface stress, surface piezoelectricity and bulk flexoelectricity, a modified Euler-Bernoulli beam model for the energy harvester is developed. After deriving the requisite energy expressions, the extended Hamilton's principle and the assumed-modes method are employed to obtain the discrete electromechanical Euler-Lagrange's equations. Then, the expressions of the steady-state electromechanical responses are given for harmonic base excitation. Numerical simulations are conducted to show the output voltage and the output power of the flexoelectric energy harvesters with different materials and sizes. Particular emphasis is given to the surface effects on the performance of the energy harvesters. It is found that the surface effects are sensitive to the beam geometries and the surface material constants, and the effect of residual surface stress is more significant than that of the surface elasticity and the surface piezoelectricity. The axial deformation of the beam is also considered in the model to account for the electromechanical coupling due to piezoelectricity, and results indicate that piezoelectricity will diminish the output electrical quantities for the case investigated. This work could lead to the development of flexoelectric energy harvesters that can make the micro- and nanoscale sensor systems autonomous.

  10. The SRFR 5 modeling system for surface irrigation

    Science.gov (United States)

    The SRFR program is a modeling system for surface irrigation. It is a central component of WinSRFR, a software package for the hydraulic analysis of surface irrigation systems. SRFR solves simplified versions of the equations of unsteady open channel flow coupled to a user selected infiltration mod...

  11. Mathematical and computer modeling of component surface shaping

    Science.gov (United States)

    Lyashkov, A.

    2016-04-01

    The process of shaping technical surfaces is an interaction of a tool (a shape element) and a component (a formable element or a workpiece) in their relative movements. It was established that the main objects of formation are: 1) a discriminant of a surfaces family, formed by the movement of the shape element relatively the workpiece; 2) an enveloping model of the real component surface obtained after machining, including transition curves and undercut lines; 3) The model of cut-off layers obtained in the process of shaping. When modeling shaping objects there are a lot of insufficiently solved or unsolved issues that make up a single scientific problem - a problem of qualitative shaping of the surface of the tool and then the component surface produced by this tool. The improvement of known metal-cutting tools, intensive development of systems of their computer-aided design requires further improvement of the methods of shaping the mating surfaces. In this regard, an important role is played by the study of the processes of shaping of technical surfaces with the use of the positive aspects of analytical and numerical mathematical methods and techniques associated with the use of mathematical and computer modeling. The author of the paper has posed and has solved the problem of development of mathematical, geometric and algorithmic support of computer-aided design of cutting tools based on computer simulation of the shaping process of surfaces.

  12. Land Surface Verification Toolkit (LVT) - A Generalized Framework for Land Surface Model Evaluation

    Science.gov (United States)

    Kumar, Sujay V.; Peters-Lidard, Christa D.; Santanello, Joseph; Harrison, Ken; Liu, Yuqiong; Shaw, Michael

    2011-01-01

    Model evaluation and verification are key in improving the usage and applicability of simulation models for real-world applications. In this article, the development and capabilities of a formal system for land surface model evaluation called the Land surface Verification Toolkit (LVT) is described. LVT is designed to provide an integrated environment for systematic land model evaluation and facilitates a range of verification approaches and analysis capabilities. LVT operates across multiple temporal and spatial scales and employs a large suite of in-situ, remotely sensed and other model and reanalysis datasets in their native formats. In addition to the traditional accuracy-based measures, LVT also includes uncertainty and ensemble diagnostics, information theory measures, spatial similarity metrics and scale decomposition techniques that provide novel ways for performing diagnostic model evaluations. Though LVT was originally designed to support the land surface modeling and data assimilation framework known as the Land Information System (LIS), it also supports hydrological data products from other, non-LIS environments. In addition, the analysis of diagnostics from various computational subsystems of LIS including data assimilation, optimization and uncertainty estimation are supported within LVT. Together, LIS and LVT provide a robust end-to-end environment for enabling the concepts of model data fusion for hydrological applications. The evolving capabilities of LVT framework are expected to facilitate rapid model evaluation efforts and aid the definition and refinement of formal evaluation procedures for the land surface modeling community.

  13. Land surface Verification Toolkit (LVT – a generalized framework for land surface model evaluation

    Directory of Open Access Journals (Sweden)

    S. V. Kumar

    2012-02-01

    Full Text Available Model evaluation and verification are key in improving the usage and applicability of simulation models for real-world applications. In this article, the development and capabilities of a formal system for land surface model evaluation called the Land surface Verification Toolkit (LVT is described. LVT is designed to provide an integrated environment for systematic land model evaluation and facilitates a range of verification approaches and analysis capabilities. LVT operates across multiple temporal and spatial scales and employs a large suite of in-situ, remotely sensed and other model and reanalysis datasets in their native formats. In addition to the traditional accuracy-based measures, LVT also includes uncertainty and ensemble diagnostics, information theory measures, spatial similarity metrics and scale decomposition techniques that provide novel ways for performing diagnostic model evaluations. Though LVT was originally designed to support the land surface modeling and data assimilation framework known as the Land Information System (LIS, it supports hydrological data products from non-LIS environments as well. In addition, the analysis of diagnostics from various computational subsystems of LIS including data assimilation, optimization and uncertainty estimation are supported within LVT. Together, LIS and LVT provide a robust end-to-end environment for enabling the concepts of model data fusion for hydrological applications. The evolving capabilities of LVT framework are expected to facilitate rapid model evaluation efforts and aid the definition and refinement of formal evaluation procedures for the land surface modeling community.

  14. Land surface Verification Toolkit (LVT – a generalized framework for land surface model evaluation

    Directory of Open Access Journals (Sweden)

    S. V. Kumar

    2012-06-01

    Full Text Available Model evaluation and verification are key in improving the usage and applicability of simulation models for real-world applications. In this article, the development and capabilities of a formal system for land surface model evaluation called the Land surface Verification Toolkit (LVT is described. LVT is designed to provide an integrated environment for systematic land model evaluation and facilitates a range of verification approaches and analysis capabilities. LVT operates across multiple temporal and spatial scales and employs a large suite of in-situ, remotely sensed and other model and reanalysis datasets in their native formats. In addition to the traditional accuracy-based measures, LVT also includes uncertainty and ensemble diagnostics, information theory measures, spatial similarity metrics and scale decomposition techniques that provide novel ways for performing diagnostic model evaluations. Though LVT was originally designed to support the land surface modeling and data assimilation framework known as the Land Information System (LIS, it supports hydrological data products from non-LIS environments as well. In addition, the analysis of diagnostics from various computational subsystems of LIS including data assimilation, optimization and uncertainty estimation are supported within LVT. Together, LIS and LVT provide a robust end-to-end environment for enabling the concepts of model data fusion for hydrological applications. The evolving capabilities of LVT framework are expected to facilitate rapid model evaluation efforts and aid the definition and refinement of formal evaluation procedures for the land surface modeling community.

  15. Advanced microwave forward model for the land surface data assimilation

    Science.gov (United States)

    Park, Chang-Hwan; Pause, Marion; Gayler, Sebastian; Wollschlaeger, Ute; Jackson, Thomas J.; LeDrew, Ellsworth; Behrendt, Andreas; Wulfmeyer, Volker

    2015-04-01

    From local to global scales, microwave remote-sensing techniques can provide temporally and spatially highly resolved observations of land surface properties including soil moisture and temperature as well as the state of vegetation. These variables are critical for agricultural productivity and water resource management. Furthermore, having accurate information of these variables allows us to improve the performances of numerical weather forecasts and climate prediction models. However, it is challenging to translate a measured brightness temperature into the multiple land surface properties because of the inherent inversion problem. In this study, we introduce a novel forward model for microwave remote sensing to resolve this inversion problem and to close the gap between land surface modeling and observations. It is composed of the Noah-MP land surface model as well as new models for the dielectric mixing and the radiative transfer. For developing a realistic forward operator, the land surface model must simulate soil and vegetation processes properly. The Noah-MP land surface model provides an excellent starting point because it contains already a sophisticated soil texture and land cover data set. Soil moisture transport is derived using the Richards equation in combination with a set of soil hydraulic parameters. Vegetation properties are considered using several photosynthesis models with different complexity. The energy balance is closed for the top soil and the vegetation layers. The energy flux becomes more realistic due to including not only the volumetric ratio of land surface properties but also their surface fraction as sub-grid scale information (semitile approach). Dielectric constant is the fundamental link to quantify the land surface properties. Our physical based new dielectric-mixing model is superior to previous calibration and semi-empirical approaches. Furthermore, owing to the consideration of the oversaturated surface dielectric behaviour

  16. Microscopic Analysis and Modeling of Airport Surface Sequencing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Although a number of airportal surface models exist and have been successfully used for analysis of airportal operations, only recently has it become possible to...

  17. Sevoflurane Remifentanil Interaction Comparison of Different Response Surface Models

    NARCIS (Netherlands)

    Heyse, Bjorn; Proost, Johannes H.; Schumacher, Peter M.; Bouillon, Thomas W.; Vereecke, Hugo E. M.; Eleveld, Douglas J.; Luginbuehl, Martin; Struys, Michel M. R. F.

    2012-01-01

    Background: Various pharmacodynamic response surface models have been developed to quantitatively describe the relationship between two or more drug concentrations with their combined clinical effect. We examined the interaction of remifentanil and sevoflurane on the probability of tolerance to shak

  18. Surface Ship Shock Modeling and Simulation: Two-Dimensional Analysis

    Directory of Open Access Journals (Sweden)

    Young S. Shin

    1998-01-01

    Full Text Available The modeling and simulation of the response of a surface ship system to underwater explosion requires an understanding of many different subject areas. These include the process of underwater explosion events, shock wave propagation, explosion gas bubble behavior and bubble-pulse loading, bulk and local cavitation, free surface effect, fluid-structure interaction, and structural dynamics. This paper investigates the effects of fluid-structure interaction and cavitation on the response of a surface ship using USA-NASTRAN-CFA code. First, the one-dimensional Bleich-Sandler model is used to validate the approach, and second, the underwater shock response of a two-dimensional mid-section model of a surface ship is predicted with a surrounding fluid model using a constitutive equation of a bilinear fluid which does not allow transmission of negative pressures.

  19. Including Finite Surface Span Effects in Empirical Jet-Surface Interaction Noise Models

    Science.gov (United States)

    Brown, Clifford A.

    2016-01-01

    The effect of finite span on the jet-surface interaction noise source and the jet mixing noise shielding and reflection effects is considered using recently acquired experimental data. First, the experimental setup and resulting data are presented with particular attention to the role of surface span on far-field noise. These effects are then included in existing empirical models that have previously assumed that all surfaces are semi-infinite. This extended abstract briefly describes the experimental setup and data leaving the empirical modeling aspects for the final paper.

  20. Evaluation of BAER surface model for aerosol optical thickness retrieval over land surface

    Directory of Open Access Journals (Sweden)

    Y. S. Chiang

    2012-04-01

    Full Text Available Estimation of surface reflectance is essential for an accurate retrieval of aerosol optical thickness (AOT by satellite remote sensing approach. Due to the variability of surface reflectance over land surfaces, a surface model is required to take into account the crucial factor controlling this variability. In the present study, we attempted to simulate surface reflectance in the short-wave channels with two methods, namely the land cover type dependent method and a two-source linear model. In the two-source linear model, we assumed that the spectral property can be described by a mixture of vegetated and non-vegetated area, and both the normalized difference vegetation index (NDVI, and the vegetation continuous field (VCF was applied to summarize this surface characteristic. By comparing our estimation with surface reflectance data derived from Moderate Resolution Imaging Spectroradiometer (MODIS, it indicated that the land cover type approach did not provide a better estimation because of inhomogeneous land cover pattern and the mixing pixel properties. For the two-source linear method, the study suggested that the use of NDVI as parameterization for vegetation fraction can reflect the spectral behavior of shortwave surface reflectance, despite of some deviation due to the averaging characteristics in our linear combination process. A channel-dependent offset and scalar factor could enhance reflectance estimation and further improve AOT retrieval by the current Bremen AErosol Retrieval (BAER approach.

  1. A model of the ground surface temperature for micrometeorological analysis

    Science.gov (United States)

    Leaf, Julian S.; Erell, Evyatar

    2017-07-01

    Micrometeorological models at various scales require ground surface temperature, which may not always be measured in sufficient spatial or temporal detail. There is thus a need for a model that can calculate the surface temperature using only widely available weather data, thermal properties of the ground, and surface properties. The vegetated/permeable surface energy balance (VP-SEB) model introduced here requires no a priori knowledge of soil temperature or moisture at any depth. It combines a two-layer characterization of the soil column following the heat conservation law with a sinusoidal function to estimate deep soil temperature, and a simplified procedure for calculating moisture content. A physically based solution is used for each of the energy balance components allowing VP-SEB to be highly portable. VP-SEB was tested using field data measuring bare loess desert soil in dry weather and following rain events. Modeled hourly surface temperature correlated well with the measured data (r 2 = 0.95 for a whole year), with a root-mean-square error of 2.77 K. The model was used to generate input for a pedestrian thermal comfort study using the Index of Thermal Stress (ITS). The simulation shows that the thermal stress on a pedestrian standing in the sun on a fully paved surface, which may be over 500 W on a warm summer day, may be as much as 100 W lower on a grass surface exposed to the same meteorological conditions.

  2. Biological Surface Adsorption Index of Nanomaterials: Modelling Surface Interactions of Nanomaterials with Biomolecules.

    Science.gov (United States)

    Chen, Ran; Riviere, Jim E

    2017-01-01

    Quantitative analysis of the interactions between nanomaterials and their surrounding environment is crucial for safety evaluation in the application of nanotechnology as well as its development and standardization. In this chapter, we demonstrate the importance of the adsorption of surrounding molecules onto the surface of nanomaterials by forming biocorona and thus impact the bio-identity and fate of those materials. We illustrate the key factors including various physical forces in determining the interaction happening at bio-nano interfaces. We further discuss the mathematical endeavors in explaining and predicting the adsorption phenomena, and propose a new statistics-based surface adsorption model, the Biological Surface Adsorption Index (BSAI), to quantitatively analyze the interaction profile of surface adsorption of a large group of small organic molecules onto nanomaterials with varying surface physicochemical properties, first employing five descriptors representing the surface energy profile of the nanomaterials, then further incorporating traditional semi-empirical adsorption models to address concentration effects of solutes. These Advancements in surface adsorption modelling showed a promising development in the application of quantitative predictive models in biological applications, nanomedicine, and environmental safety assessment of nanomaterials.

  3. Migration velocity modeling based on common reflection surface gather

    Institute of Scientific and Technical Information of China (English)

    李振春; 姚云霞; 马在田; 王华忠

    2003-01-01

    The common-reflection-surface (CRS) stacking is a new seismic imaging method, which only depends on seismic three parameters and near-surface velocity instead of macro-velocity model. According to optimized three parameters obtained by CRS stacking, we derived an analytical relationship between three parameters and migration velocity field, and put forward CRS gather migration velocity modeling method, which realize velocity estimation by optimizing three parameters in CRS gather. The test of a sag model proved that this method is more effective and adaptable for velocity modeling of a complex geological body, and the accuracy of velocity analysis depends on the precision of optimized three parameters.

  4. A surface-scattering model satisfying energy conservation and reciprocity

    CERN Document Server

    Sasihithlu, Karthik; Hugonin, Jean-Paul; Greffet, Jean-Jacques

    2015-01-01

    In order for surface scattering models to be accurate they must necessarily satisfy energy conservation and reciprocity principles. Roughness scattering models based on Kirchoff's approximation or perturbation theory do not satisfy these criteria in all frequency ranges. Here we present a surface scattering model based on analysis of scattering from a layer of particles on top of a substrate in the dipole approximation which satisfies both energy conservation and reciprocity and is thus accurate in all frequency ranges. The model takes into account the absorption in the substrate induced by the particles but does not take into account the near-field interactions between the particles.

  5. Developing an Empirical Model for Jet-Surface Interaction Noise

    Science.gov (United States)

    Brown, Clifford A.

    2014-01-01

    The process of developing an empirical model for jet-surface interaction noise is described and the resulting model evaluated. Jet-surface interaction noise is generated when the high-speed engine exhaust from modern tightly integrated or conventional high-bypass ratio engine aircraft strikes or flows over the airframe surfaces. An empirical model based on an existing experimental database is developed for use in preliminary design system level studies where computation speed and range of configurations is valued over absolute accuracy to select the most promising (or eliminate the worst) possible designs. The model developed assumes that the jet-surface interaction noise spectra can be separated from the jet mixing noise and described as a parabolic function with three coefficients: peak amplitude, spectral width, and peak frequency. These coefficients are fit to functions of surface length and distance from the jet lipline to form a characteristic spectra which is then adjusted for changes in jet velocity and/or observer angle using scaling laws from published theoretical and experimental work. The resulting model is then evaluated for its ability to reproduce the characteristic spectra and then for reproducing spectra measured at other jet velocities and observer angles; successes and limitations are discussed considering the complexity of the jet-surface interaction noise versus the desire for a model that is simple to implement and quick to execute.

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

    CERN Document Server

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

    1992-01-01

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

  7. Computational molecular basis for improved silica surface complexation models

    Energy Technology Data Exchange (ETDEWEB)

    Sahai, Nita; Rosso, Kevin M.

    2006-06-06

    The acidity and reactivity of surface sites on amorphous and crystalline polymorphs of silica and other oxides control their thermodynamic stability and kinetic reactivity towards reactants in surface-controlled processes of environmental, industrial, biomedical and technological relevance. Recent advances in computational methodologies such as CPMD and increasing computer power combined with spectroscopic measurements are now making it possible to link, with an impressive degree of accuracy, the molecular-level description of these processes to phenomenological, surface complexation models The future challenge now lies in linking mesoscale properties at the nanometer scale to phenomenological models that will afford a more intuitive understanding of the systems under consideration.

  8. Integrated Surface/subsurface flow modeling in PFLOTRAN

    Energy Technology Data Exchange (ETDEWEB)

    Painter, Scott L [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-10-01

    Understanding soil water, groundwater, and shallow surface water dynamics as an integrated hydrological system is critical for understanding the Earth’s critical zone, the thin outer layer at our planet’s surface where vegetation, soil, rock, and gases interact to regulate the environment. Computational tools that take this view of soil moisture and shallow surface flows as a single integrated system are typically referred to as integrated surface/subsurface hydrology models. We extend the open-source, highly parallel, subsurface flow and reactive transport simulator PFLOTRAN to accommodate surface flows. In contrast to most previous implementations, we do not represent a distinct surface system. Instead, the vertical gradient in hydraulic head at the land surface is neglected, which allows the surface flow system to be eliminated and incorporated directly into the subsurface system. This tight coupling approach leads to a robust capability and also greatly simplifies implementation in existing subsurface simulators such as PFLOTRAN. Successful comparisons to independent numerical solutions build confidence in the approximation and implementation. Example simulations of the Walker Branch and East Fork Poplar Creek watersheds near Oak Ridge, Tennessee demonstrate the robustness of the approach in geometrically complex applications. The lack of a robust integrated surface/subsurface hydrology capability had been a barrier to PFLOTRAN’s use in critical zone studies. This work addresses that capability gap, thus enabling PFLOTRAN as a community platform for building integrated models of the critical zone.

  9. Modified Critical State Two-Surface Plasticity Model for Sands

    DEFF Research Database (Denmark)

    Sørensen, Kris Wessel; Nielsen, Søren Kjær; Shajarati, Amir

    This article describes the outline of a numerical integration scheme for a critical state two-surface plasticity model for sands. The model is slightly modified by LeBlanc (2008) compared to the original formulation presented by Manzari and Dafalias (1997) and has the ability to correctly model...... calculations can be performed with the Forward Euler integration scheme. Furthermore, the model is formulated for a single point....

  10. A microwave emissivity model of sea surface under wave breaking

    Institute of Scientific and Technical Information of China (English)

    Wei En-Bo; Ge Yong

    2005-01-01

    With the effective medium approximation theory of composites, a remedial model is proposed for estimating the microwave emissivity of sea surface under wave breaking driven by strong wind on the basis of an empirical model given by Pandey and Kakar. In our model, the effects of the shapes of seawater droplets and the thickness of whitecap layer (i.e. a composite layer of air and sea water droplets) over the sea surface on the microwave emissivity are investigated by calculating the effective dielectric constant of whitecaps layer. The wind speed is included in our model, and the responses of water droplets shapes, such as sphere and ellipsoid, to the emissivity are also discussed at different microwave frequencies. The model is in good agreement with the experimental data of microwave emissivity of sea surface at microwave frequencies of 6.6, 10.7 and 37GHz.

  11. Liquid-drop model for the surface energy of nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, Karuna Kar, E-mail: nanda@mrc.iisc.ernet.in [Materials Research Centre, Indian Institute of Science, Bangalore 560012 (India)

    2012-04-09

    Based on the liquid-drop model, we have evaluated the Tolman length and surface energy of nanoparticles for different elements and compared with other theoretical models as well as the available simulated data. The predictions of the model show good agreement with the simulated results. Like the cohesive energy and melting temperature, the size-dependency of surface energy is also shape-dependent. -- Highlights: ► Derivation of size-dependent surface energy based on a liquid-drop model. ► Evaluated the Tolman length for different elements. ► Predictions of the model show good agreement with the simulated results. ► Shape-dependent Tolman's length.

  12. Hybrid Surface Mesh Adaptation for Climate Modeling

    Institute of Scientific and Technical Information of China (English)

    Ahmed Khamayseh; Valmor de Almeida; Glen Hansen

    2008-01-01

    Solution-driven mesh adaptation is becoming quite popular for spatial error control in the numerical simulation of complex computational physics applications, such as climate modeling. Typically, spatial adaptation is achieved by element subdivision (h adaptation) with a primary goal of resolving the local length scales of interest. A second, lesspopular method of spatial adaptivity is called "mesh motion" (r adaptation); the smooth repositioning of mesh node points aimed at resizing existing elements to capture the local length scales. This paper proposes an adaptation method based on a combination of both element subdivision and node point repositioning (rh adaptation). By combining these two methods using the notion of a mobility function, the proposed approach seeks to increase the flexibility and extensibility of mesh motion algorithms while providing a somewhat smoother transition between refined regions than is pro-duced by element subdivision alone. Further, in an attempt to support the requirements of a very general class of climate simulation applications, the proposed method is de-signed to accommodate unstructured, polygonal mesh topologies in addition to the most popular mesh types.

  13. Standard fire behavior fuel models: a comprehensive set for use with Rothermel's surface fire spread model

    Science.gov (United States)

    Joe H. Scott; Robert E. Burgan

    2005-01-01

    This report describes a new set of standard fire behavior fuel models for use with Rothermel's surface fire spread model and the relationship of the new set to the original set of 13 fire behavior fuel models. To assist with transition to using the new fuel models, a fuel model selection guide, fuel model crosswalk, and set of fuel model photos are provided.

  14. Modeling Apple Surface Temperature Dynamics Based on Weather Data

    Directory of Open Access Journals (Sweden)

    Lei Li

    2014-10-01

    Full Text Available The exposure of fruit surfaces to direct sunlight during the summer months can result in sunburn damage. Losses due to sunburn damage are a major economic problem when marketing fresh apples. The objective of this study was to develop and validate a model for simulating fruit surface temperature (FST dynamics based on energy balance and measured weather data. A series of weather data (air temperature, humidity, solar radiation, and wind speed was recorded for seven hours between 11:00–18:00 for two months at fifteen minute intervals. To validate the model, the FSTs of “Fuji” apples were monitored using an infrared camera in a natural orchard environment. The FST dynamics were measured using a series of thermal images. For the apples that were completely exposed to the sun, the RMSE of the model for estimating FST was less than 2.0 °C. A sensitivity analysis of the emissivity of the apple surface and the conductance of the fruit surface to water vapour showed that accurate estimations of the apple surface emissivity were important for the model. The validation results showed that the model was capable of accurately describing the thermal performances of apples under different solar radiation intensities. Thus, this model could be used to more accurately estimate the FST relative to estimates that only consider the air temperature. In addition, this model provides useful information for sunburn protection management.

  15. Simultaneous application of dissolution/precipitation and surface complexation/surface precipitation modeling to contaminant leaching

    NARCIS (Netherlands)

    Apul, D.S.; Gardner, K.H.; Eighmy, T.T.; Fallman, A.M.; Comans, R.N.J.

    2005-01-01

    This paper discusses the modeling of anion and cation leaching from complex matrixes such as weathered steel slag. The novelty of the method is its simultaneous application of the theoretical models for solubility, competitive sorption, and surface precipitation phenomena to a complex system. Select

  16. Adhesion of perfume-filled microcapsules to model fabric surfaces.

    Science.gov (United States)

    He, Yanping; Bowen, James; Andrews, James W; Liu, Min; Smets, Johan; Zhang, Zhibing

    2014-01-01

    The retention and adhesion of melamine formaldehyde (MF) microcapsules on a model fabric surface in aqueous solution were investigated using a customised flow chamber technique and atomic force microscopy (AFM). A cellulose film was employed as a model fabric surface. Modification of the cellulose with chitosan was found to increase the retention and adhesion of microcapsules on the model fabric surface. The AFM force-displacement data reveal that bridging forces resulting from the extension of cellulose chains dominate the adhesion between the microcapsule and the unmodified cellulose film, whereas electrostatic attraction helps the microcapsules adhere to the chitosan-modified cellulose film. The correlation between results obtained using these two complementary techniques suggests that the flow chamber device can be potentially used for rapid screening of the effect of chemical modification on the adhesion of microparticles to surfaces, reducing the time required to achieve an optimal formulation.

  17. Free Surface Lattice Boltzmann with Enhanced Bubble Model

    CERN Document Server

    Anderl, Daniela; Rauh, Cornelia; Rüde, Ulrich; Delgado, Antonio

    2016-01-01

    This paper presents an enhancement to the free surface lattice Boltzmann method (FSLBM) for the simulation of bubbly flows including rupture and breakup of bubbles. The FSLBM uses a volume of fluid approach to reduce the problem of a liquid-gas two-phase flow to a single-phase free surface simulation. In bubbly flows compression effects leading to an increase or decrease of pressure in the suspended bubbles cannot be neglected. Therefore, the free surface simulation is augmented by a bubble model that supplies the missing information by tracking the topological changes of the free surface in the flow. The new model presented here is capable of handling the effects of bubble breakup and coalesce without causing a significant computational overhead. Thus, the enhanced bubble model extends the applicability of the FSLBM to a new range of practically relevant problems, like bubble formation and development in chemical reactors or foaming processes.

  18. Contour-Based Surface Reconstruction using MPU Implicit Models.

    Science.gov (United States)

    Braude, Ilya; Marker, Jeffrey; Museth, Ken; Nissanov, Jonathan; Breen, David

    2007-03-01

    This paper presents a technique for creating a smooth, closed surface from a set of 2D contours, which have been extracted from a 3D scan. The technique interprets the pixels that make up the contours as points in ℝ(3) and employs Multi-level Partition of Unity (MPU) implicit models to create a surface that approximately fits to the 3D points. Since MPU implicit models additionally require surface normal information at each point, an algorithm that estimates normals from the contour data is also described. Contour data frequently contains noise from the scanning and delineation process. MPU implicit models provide a superior approach to the problem of contour-based surface reconstruction, especially in the presence of noise, because they are based on adaptive implicit functions that locally approximate the points within a controllable error bound. We demonstrate the effectiveness of our technique with a number of example datasets, providing images and error statistics generated from our results.

  19. Capillary rise of water in hydrophilic nanopores

    CERN Document Server

    Gruener, Simon; Wallacher, Dirk; Kityk, Andriy V; Huber, Patrick; 10.1103/PhysRevE.79.067301

    2009-01-01

    We report on the capillary rise of water in three-dimensional networks of hydrophilic silica pores with 3.5nm and 5nm mean radii, respectively (porous Vycor monoliths). We find classical square root of time Lucas-Washburn laws for the imbibition dynamics over the entire capillary rise times of up to 16h investigated. Provided we assume two preadsorbed strongly bound layers of water molecules resting at the silica walls, which corresponds to a negative velocity slip length of -0.5nm for water flow in silica nanopores, we can describe the filling process by a retained fluidity and capillarity of water in the pore center. This anticipated partitioning in two dynamic components reflects the structural-thermodynamic partitioning in strongly silica bound water layers and capillary condensed water in the pore center which is documented by sorption isotherm measurements.

  20. Hydrophilic Polymer-associated Ischemic Enterocolitis.

    Science.gov (United States)

    Chavez, Jesus A; Chen, Wei; Frankel, Wendy L; Arnold, Christina A

    2017-02-01

    Hydrophilic polymer coating of medical devices serves to lubricate the device and prevent device-related complications. The coating can be mechanically disrupted and result in downstream injury via presumed thromboembolism. This process has been reported in the brain, heart, lung, and skin, and has been replicated through animal studies and in vitro histologic processing of the polymer coating. We report the first description of hydrophilic polymer-associated ischemic enterocolitis in a series of 7 specimens (small bowel=2, colon=4, aortic thrombus=1) from 3 patients. We report a 4% incidence among all patients with an ischemic bowel resection between April 29, 2014 and August 8, 2016. All patients developed bowel ischemia within 1 day of aortic repair, and all bowel resection specimens showed polymers, mainly in the submucosal vessels in areas of extensive ischemia. The polymers appeared as basophilic, intravascular, serpiginous structures. In a patient who developed acute paralysis after the aortic repair, identical polymers were identified in the aortic thrombus and the ischemic bowel segment. We demonstrate that the polymers display an altered morphology over time and with various graft types, and that the degrading polymers are associated with a foreign body giant cell reaction. Special stains can aid in diagnosis, with the polymers turquoise on a colloidal iron stain, pink on von Kossa and mucicarmine stains, and pale blue on trichrome. Clinical follow-up was available up to 115 weeks: 1 patient died, and 2 are alive and well. In summary, we report a new diagnostic entity to be considered in the differential diagnosis of iatrogenic ischemic injuries in the gastrointestinal tract. Awareness of this entity is important to elucidate the cause of ischemia and to prevent misdiagnosis of the polymers and their associated giant cell reaction as a parasitic infection, granulomatous vasculitis, sarcoidosis, and idiopathic inflammatory bowel disease.

  1. Photocatalysis and photoinduced hydrophilicity of WO3 thin films with underlying Pt nanoparticles.

    Science.gov (United States)

    Miyauchi, Masahiro

    2008-11-07

    The photocatalytic oxidation and photoinduced hydrophilicity of thin tungsten trioxide (WO(3)) films coupled with platinum (Pt) nanoparticles were investigated. WO(3) films with underlying Pt nanoparticles (WO(3)/Pt/substrate) and those with overlying Pt nanoparticles (Pt/WO(3)/substrate) were synthesized by sputtering and sol-gel methods. Between these films, underlying Pt nanoparticles greatly enhanced the photocatalytic oxidation activity of WO(3) without decreasing the photoinduced hydrophilic conversion. However, overlying Pt nanoparticles deteriorated the hydrophilicity of WO(3) because the Pt nanoparticle surface was hydrophobic. The enhanced photocatalytic reaction by the Pt nanoparticles was attributed to the multi-electron reduction in Pt, which is caused by the injected electrons from the conduction band of WO(3). The relationship between photocatalytic activity and thin film structure, including the size of Pt nanoparticles, the thickness and porosity of the WO(3) layer, were investigated. Consequently, the optimum structure for high performance in both photocatalysis and photoinduced hydrophilicity was WO(3) (50 nm)/Pt(1.5 nm)/substrate, and this film exhibited a significant self-cleaning property even under visible light irradiation.

  2. Hydrophilic quantum dots stability against an external low-strength electric field

    Energy Technology Data Exchange (ETDEWEB)

    Goftman, Valentina V., E-mail: Valentina.Goftman@UGent.be [Department of General and Inorganic Chemistry, Chemistry Institute, Saratov State University, Astrakhanskaya 83, 410012 Saratov (Russian Federation); Laboratory of Food Analysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent (Belgium); Pankratov, Vladislav A.; Markin, Alexey V. [Department of General and Inorganic Chemistry, Chemistry Institute, Saratov State University, Astrakhanskaya 83, 410012 Saratov (Russian Federation); Ginste, Dries Vande [IBCN/Electromagnetics Group, Department of Information Technology, Ghent University/iMinds, Sint-Pietersnieuwstraat 41, 9000 B-Gent (Belgium); De Saeger, Sarah [Laboratory of Food Analysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent (Belgium); Goryacheva, Irina Yu. [Department of General and Inorganic Chemistry, Chemistry Institute, Saratov State University, Astrakhanskaya 83, 410012 Saratov (Russian Federation)

    2016-02-15

    Graphical abstract: - Highlights: • Silica-coated and polymer-covered hydrophilic quantum dots are synthesized and characterized. • Impact of low-strength electric field is compared for both hydrophilic shells. • Silica shell protects the quantum dots fluorescent core when being subjected to a low-strength electric field. - Abstract: Since the stability of nanobiolabels plays a key role in their application, we thoroughly investigated how an external, low-strength electric field impacts on the fluorescent properties of hydrophilic quantum dots (QDs). Two fundamentally different approaches were applied to make the QDs water-soluble, i.e. ligand exchange (namely silica covering) and encapsulation with an amphiphilic polymer. It is shown that, even under a low-strength electric field, the polymer-coated QDs could lose 90% of their brightness because of the weak interaction between the QD's surface and the polymeric molecule. Silica-covered QDs, on the contrary, stay bright and stable owing to the covalently attached dense silica shell. These findings, which are clearly explained and illustrated in the present paper, are of critical importance in the context of hydrophilic QDs’ bioapplication.

  3. Molecular Dynamics Simulations of Water Droplets On Hydrophilic Silica Surfaces

    DEFF Research Database (Denmark)

    Zambrano, Harvey A; Walther, Jens Honore; Jaffe, Richard L.

    2009-01-01

    Wetting is essential and ubiquitous in a variety of natural and technological processes. Silicon dioxides-water systems are abundant in nature and play fundamental roles in a vast variety of novel science and engineering activities such as silicon based devices, nanoscale lab on a chip systems...... and DNA microarrays technologies.Although extensive experimental, theoretical and computational work has been devoted to study the nature of the interaction between silica and water, at the molecular level a complete understanding of silica-water systems has not been reached. Contact angle computations...

  4. Molecular Dynamics Simulations of Water Droplets On Hydrophilic Silica Surfaces

    DEFF Research Database (Denmark)

    Zambrano, Harvey A; Walther, Jens Honore; Jaffe, Richard L.

    2009-01-01

    Wetting is essential and ubiquitous in a variety of natural and technological processes. Silicon dioxides-water systems are abundant in nature and play fundamental roles in a vast variety of novel science and engineering activities such as silicon based devices, nanoscale lab on a chip systems an...

  5. Finite Element Model Updating Using Response Surface Method

    CERN Document Server

    Marwala, Tshilidzi

    2007-01-01

    This paper proposes the response surface method for finite element model updating. The response surface method is implemented by approximating the finite element model surface response equation by a multi-layer perceptron. The updated parameters of the finite element model were calculated using genetic algorithm by optimizing the surface response equation. The proposed method was compared to the existing methods that use simulated annealing or genetic algorithm together with a full finite element model for finite element model updating. The proposed method was tested on an unsymmetri-cal H-shaped structure. It was observed that the proposed method gave the updated natural frequen-cies and mode shapes that were of the same order of accuracy as those given by simulated annealing and genetic algorithm. Furthermore, it was observed that the response surface method achieved these results at a computational speed that was more than 2.5 times as fast as the genetic algorithm and a full finite element model and 24 ti...

  6. Alloy Design Workbench-Surface Modeling Package Developed

    Science.gov (United States)

    Abel, Phillip B.; Noebe, Ronald D.; Bozzolo, Guillermo H.; Good, Brian S.; Daugherty, Elaine S.

    2003-01-01

    NASA Glenn Research Center's Computational Materials Group has integrated a graphical user interface with in-house-developed surface modeling capabilities, with the goal of using computationally efficient atomistic simulations to aid the development of advanced aerospace materials, through the modeling of alloy surfaces, surface alloys, and segregation. The software is also ideal for modeling nanomaterials, since surface and interfacial effects can dominate material behavior and properties at this level. Through the combination of an accurate atomistic surface modeling methodology and an efficient computational engine, it is now possible to directly model these types of surface phenomenon and metallic nanostructures without a supercomputer. Fulfilling a High Operating Temperature Propulsion Components (HOTPC) project level-I milestone, a graphical user interface was created for a suite of quantum approximate atomistic materials modeling Fortran programs developed at Glenn. The resulting "Alloy Design Workbench-Surface Modeling Package" (ADW-SMP) is the combination of proven quantum approximate Bozzolo-Ferrante-Smith (BFS) algorithms (refs. 1 and 2) with a productivity-enhancing graphical front end. Written in the portable, platform independent Java programming language, the graphical user interface calls on extensively tested Fortran programs running in the background for the detailed computational tasks. Designed to run on desktop computers, the package has been deployed on PC, Mac, and SGI computer systems. The graphical user interface integrates two modes of computational materials exploration. One mode uses Monte Carlo simulations to determine lowest energy equilibrium configurations. The second approach is an interactive "what if" comparison of atomic configuration energies, designed to provide real-time insight into the underlying drivers of alloying processes.

  7. Hydrophilic modification of PVDF microfiltration membranes by adsorption of facial amphiphile cholic acid.

    Science.gov (United States)

    Hu, Meng-Xin; Li, Ji-Nian; Zhang, Shi-Lin; Li, Liang; Xu, Zhi-Kang

    2014-11-01

    Amphiphilic molecules have been widely used in surface modification of polymeric materials. Bile acids are natural biological compounds and possess special facial amphiphilic structure with a unusual distribution of hydrophobic and hydrophilic regions. Based on the facial amphiphilicity, cholic acid (CA), one of the bile acids, was utilized for the hydrophilic modification of poly(vinylidene fluoride) (PVDF) microfiltration membranes via the hydrophobic interactions between the hydrophobic face of CA and the membrane surfaces. Ethanol, methanol, and water were respectively used as solvent during CA adsorption procedure. Their polarity affects the CA adsorption amount, as similar to CA concentration and adsorption time. There are no changes on the membrane surface morphology after CA adsorption. The hydrophilicity of PVDF membranes is greatly enhanced and the water drops permeates into the CA modified membranes quickly after modification. All these factors benefit to the permeation flux of membrane for water. When CA concentration is higher than 0.088 M, the water permeation flux is doubled as compared with the nascent PVDF membrane and shows a good stability during filtration procedure. These results reveal the promising potential of facial amphiphilic bile acids for the surface modification of polymeric materials.

  8. Modeling Alaska boreal forests with a controlled trend surface approach

    Science.gov (United States)

    Mo Zhou; Jingjing Liang

    2012-01-01

    An approach of Controlled Trend Surface was proposed to simultaneously take into consideration large-scale spatial trends and nonspatial effects. A geospatial model of the Alaska boreal forest was developed from 446 permanent sample plots, which addressed large-scale spatial trends in recruitment, diameter growth, and mortality. The model was tested on two sets of...

  9. Near-surface attenuation estimation using wave-propagation modeling

    NARCIS (Netherlands)

    El Yadari, N.; Ernst, F.; Mulder, W.

    2008-01-01

    The effect of the near surface on seismic land data can be so severe that static corrections are insufficient. Full-waveform inversion followed by redatuming may be an alternative, but inversion will work only if the starting model is sufficiently close to the true model. As a first step toward dete

  10. Low-temperature CF4 plasma surface modified hydrophilic PES membrane for direct contact membrane distillation%低温CF4等离子体改性亲水聚醚砜膜及其在直接接触式膜蒸馏中的应用

    Institute of Scientific and Technical Information of China (English)

    魏星; 李雪梅; 何本桥; 殷勇; 何涛

    2011-01-01

    膜蒸馏是一种低能耗、高效率的海水淡化技术.文章借鉴了制备压力推动膜材料的思路,采用非对称、孔结构高度连通的亲水聚醚砜膜,通过CF4等离子体表面改性,将亲水膜改性为疏水膜材料,并应用于直接接触式膜蒸馏(DCMD)过程.对膜的结构,接触角和DCMD性能进行了表征.结果显示,改性后PES膜表面水接触角达120°.以4% NaC1水溶液为原料,膜蒸馏中水通量达44