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Sample records for hydrophilic solid surface

  1. 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.

  2. Controlled effect of ultrasonic cavitation on hydrophobic/hydrophilic surfaces.

    Science.gov (United States)

    Belova, Valentina; Gorin, Dmitry A; Shchukin, Dmitry G; Möhwald, Helmuth

    2011-02-01

    Controlling cavitation at the solid surface is of increasing interest, as it plays a major role in many physical and chemical processes related to the modification of solid surfaces and formation of multicomponent nanoparticles. Here, we show a selective control of ultrasonic cavitation on metal surfaces with different hydrophobicity. By applying a microcontact printing technique we successfully formed hydrophobic/hydrophilic alternating well-defined microstructures on aluminium surfaces. Fabrication of patterned surfaces provides the unique opportunity to verify a model of heterogeneous nucleation of cavitation bubbles near the solid/water interface by varying the wettability of the surface, temperature and ultrasonic power. At the initial stage of sonication (up to 30 min), microjets and shock waves resulting from the collapsing bubbles preferably impact the hydrophobic surface, whereas the hydrophilic areas of the patterned Al remain unchanged. Longer sonication periods affect both surfaces. These findings confirm the expectation that higher contact angle causes a lower energy barrier, thus cavitation dominates at the hydrophobic surfaces. Experimental results are in good agreement with expectations from nucleation theory. This paper illustrates a new approach to ultrasound induced modification of solid surfaces resulting in the formation of foam-structured metal surfaces.

  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. Water structuring and collagen adsorption at hydrophilic and hydrophobic silicon surfaces.

    Science.gov (United States)

    Cole, Daniel J; Payne, Mike C; Ciacchi, Lucio Colombi

    2009-12-28

    The adsorption of a collagen fragment on both a hydrophobic, hydrogen-terminated and a hydrophilic, natively oxidised Si surface is investigated using all-atom molecular dynamics. While favourable direct protein-surface interactions via localised contact points characterise adhesion to the hydrophilic surface, evenly spread surface/molecule contacts and stabilisation of the helical structure occurs upon adsorption on the hydrophobic surface. In the latter case, we find that adhesion is accompanied by a mutual fit between the hydrophilic/hydrophobic pattern within the protein and the layered water structure at the solid/liquid interface, which may provide an additional driving force to the classic hydrophobic effect.

  5. Enhanced Permeation of a Hydrophobic Fluid through Particles with Hydrophobic and Hydrophilic Patterned Surfaces

    OpenAIRE

    Renliang Zhang; Yousheng Xu; Binghai Wen; Nan Sheng; Haiping Fang

    2014-01-01

    The wetting properties of solid surfaces are significant in oil/gas and liquid displacement processes. It is difficult for hydrophobic fluids to permeate channels filled with hydrophilic particles and an aqueous phase, and this is thought to be the primary cause of low yields in low permeability reservoir operations. Using three-dimensional lattice Boltzmann simulations, we show that particles with hydrophobic and hydrophilic patterned surfaces can greatly improve hydrophobic fluid permeation...

  6. Adsorption of trypsin on hydrophilic and hydrophobic surfaces

    NARCIS (Netherlands)

    Koutsopoulos, Sotirios; Patzsch, Katja; Bosker, Wouter T. E.; Norde, Willem

    2007-01-01

    The adsorption of trypsin onto polystyrene and silica surfaces was investigated by reflectometry, spectroscopic methods, and atomic force microscopy (AFM). The affinity of trypsin for the hydrophobic polystyrene surface was higher than that for the hydrophilic silica surface, but steady-state

  7. 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.

  8. 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 la...

  9. 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,…

  10. Aggregation of amyloidogenic peptides near hydrophobic and hydrophilic surfaces.

    Science.gov (United States)

    Brovchenko, Ivan; Singh, Gurpreet; Winter, Roland

    2009-07-21

    The general effect of surface hydrophobicity/hydrophilicity on the aggregation of peptides is studied by simulations of oversaturated aqueous solutions of hydrophobic and hydrophilic amyloidogenic peptides. Peptide aggregation was studied in bulk solution, in solutions confined between hydrophobic boundaries (smooth planar paraffin-like surfaces and liquid-vapor interfaces) and in solutions confined between hydrophilic surfaces (smooth planar silica-like surfaces). Aggregation of hydrophobic peptides strongly enhances due to the confinement between hydrophobic surfaces with all peptides adsorbed at the boundaries and aligned predominantly parallel to them. In the other three cases considered, the peptides are repelled from the walls and do not reveal orientational ordering with respect to the surface. The degree of peptide aggregation in these cases is only slightly affected by the confinement (it is enhanced for hydrophobic peptides and decreased for hydrophilic peptides). Our results show that even a single environmental factor such as water-mediated peptide-surface interaction has a drastic effect on the degree and character of peptide aggregation. A wide diversity of possible scenarios can be expected when specific peptide-surface interactions are additionally taken into account.

  11. Enhanced solubility of piperine using hydrophilic carrier-based potent solid dispersion systems.

    Science.gov (United States)

    Thenmozhi, Kathavarayan; Yoo, Young Je

    2017-09-01

    Piperine alkaloid, an important constituent of black pepper, exhibits numerous therapeutic properties, whereas its usage as a drug is limited due to its poor solubility in aqueous medium, which leads to poor bioavailability. Herein, a new method has been developed to improve the solubility of this drug based on the development of solid dispersions with improved dissolution rate using hydrophilic carriers such as sorbitol (Sor), polyethylene glycol (PEG) and polyvinyl pyrrolidone K30 (PVP) by solvent method. Physical mixtures of piperine and carriers were also prepared for comparison. The physicochemical properties of the prepared solid dispersions were examined using SEM, TEM, DSC, XRD and FT-IR. In vitro dissolution profile of the solid dispersions was recorded and compared with that of the pure piperine and physical mixtures. The effect of these carriers on the aqueous solubility of piperine has been investigated. The solid dispersions of piperine with Sor, PEG and PVP exhibited superior performance for the dissolution of piperine with a drug release of 70%, 76% and 89%, respectively after 2 h compared to physical mixtures and pure piperine, which could be due to its transformation from crystalline to amorphous form as well as the attachment of hydrophilic carriers to the surface of poorly water-soluble piperine. Results suggest that the piperine solid dispersions prepared with improved in vitro release exhibit potential advantage in delivering poorly water-soluble piperine as an oral supplement.

  12. 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

    not in itself provide any information on why the friction coefficient is different for different material combinations. In this study, friction forces between a colloidal probe and nanostructured particle coated surfaces in an aqueous environment exhibiting different roughness length scales were measured...... 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...

  13. Autoactivation of blood factor XII at hydrophilic and hydrophobic surfaces.

    Science.gov (United States)

    Zhuo, Rui; Siedlecki, Christopher A; Vogler, Erwin A

    2006-08-01

    Contact activation of blood factor XII (FXII, Hageman factor) in neat-buffer solution is shown not to be specific for anionic hydrophilic procoagulants as proposed by the accepted biochemistry of surface activation. Rather, FXII activation in the presence of plasma proteins leads to an apparent specificity for hydrophilic surfaces that is actually due to a relative diminution of the FXII-->FXIIa reaction at hydrophobic surfaces. FXII activation in neat-buffer solution was effectively instantaneous upon contact with either hydrophilic (fully water-wettable clean glass) or hydrophobic (poorly water-wettable silanized glass) procoagulant particles, with greater FXIIa yield obtained by activation with hydrophobic procoagulants. In sharp contrast, both activation rate and yield was found to be significantly attenuated at hydrophobic surfaces in the presence of plasma proteins. Putative FXIIa produced by surface activation with both hydrophilic and hydrophobic procoagulants was shown to hydrolyze blood factor XI (FXI) to the activated form FXIa (FXIFXIIa-->FXIa) that causes FXI-deficient plasma to rapidly coagulate.

  14. Self-generation of colligative properties at hydrophilic surfaces

    OpenAIRE

    Chaplin, Martin

    2012-01-01

    The generally accepted view of osmotic pressure is that it is a colligative property, along with freezing point depression, boiling point elevation and vapour pressure lowering. These properties ideally depend on the concentration of dissolved solute molecules. Osmotic pressure, however, is also generated, without any solute, at hydrophilic surfaces. Here is presented a rationale and explanation for this phenomenon.

  15. Bacterial adhesion to surface hydrophilic and hydrophobic contact lenses

    NARCIS (Netherlands)

    Bruinsma, GM; van der Mei, HC; Busscher, HJ

    2001-01-01

    The aim of this paper was to determine the adhesion of two physico-chemically characterized bacterial strains to a surface hydrophilic (CL A, water contact angle 57 degrees) and hydrophobic (CL B, water contact angle 106 degrees) hydrogel contact lens (CL) with and without an adsorbed tear film in a

  16. Fluctuations of water near extended hydrophobic and hydrophilic surfaces.

    Science.gov (United States)

    Patel, Amish J; Varilly, Patrick; Chandler, David

    2010-02-04

    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. Our results are obtained with a biased sampling of coarse-grained densities that is easily combined with molecular dynamics integration algorithms. Our principal result is that the probability for density fluctuations of water near a hydrophobic surface, with or without surface water attractions, is akin to density fluctuations at the water-vapor interface. Specifically, the probability of density depletion near the surface is significantly larger than that in the bulk, and this enhanced probability is responsible for hydrophobic forces of assembly. In contrast, we find that the statistics of water density fluctuations near a model hydrophilic surface are similar to that in the bulk.

  17. EVALUATION OF SOLID PHASE MICROEXTRACTION FOR THE ANALYSIS OF HYDROPHILIC COMPOUNDS

    Science.gov (United States)

    Two commercially available solid phase microextractions (SPME) fibers, polyacrylate and carboxem/polydimethylsiloxane (PDMS), were evaluated for their ability to extract hydrophilic compounds from drinking water. Conditions, such as desorption time, desorption temperature, sample...

  18. Utilizing ion-pairing hydrophilic interaction chromatography solid phase extraction for efficient glycopeptide enrichment in glycoproteomics

    DEFF Research Database (Denmark)

    Mysling, Simon; Palmisano, Giuseppe; Højrup, Peter

    2010-01-01

    Glycopeptide enrichment is a prerequisite to enable structural characterization of protein glycosylation in glycoproteomics. Here we present an improved method for glycopeptide enrichment based on zwitter-ionic hydrophilic interaction chromatography solid phase extraction (ZIC-HILIC SPE...

  19. Forces between hydrophilic surfaces adsorbed with apolipoprotein AII alpha helices.

    Science.gov (United States)

    Ramos, S; Campos-Terán, J; Mas-Oliva, J; Nylander, Tommy; Castillo, R

    2008-08-19

    To provide better understanding of how a protein secondary structure affects protein-protein and protein-surface interactions, forces between amphiphilic alpha-helical proteins (human apolipoprotein AII) adsorbed on a hydrophilic surface (mica) were measured using an interferometric surface force apparatus (SFA). Forces between surfaces with adsorbed layers of this protein are mainly composed of electrostatic double layer forces at large surface distances and of steric repulsive forces at small distances. We suggest that the amphiphilicity of the alpha-helix structure facilitates the formation of protein multilayers next to the mica surfaces. We found that protein-surface interaction is stronger than protein-protein interaction, probably due to the high negative charge density of the mica surface and the high positive charge of the protein at our experimental conditions. Ellipsometry was used to follow the adsorption kinetics of this protein on hydrophilic silica, and we observed that the adsorption rate is not only controlled by diffusion, but rather by the protein-surface interaction. Our results for dimeric apolipoprotein AII are similar to those we have reported for the monomeric apolipoprotein CI, which has a similar secondary structure but a different peptide sequence and net charge. Therefore, the observed force curves seem to be a consequence of the particular features of the amphiphilic alpha-helices.

  20. 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

  1. Flocculating and dewatering performance of hydrophobic and hydrophilic solids using a thermal-sensitive copolymer.

    Science.gov (United States)

    Li, Shulei; Liao, Yinfei; Li, Guosheng; Li, Zhen; Cao, Yijun

    2017-07-01

    Thermal-sensitive polymers have been tested on settling, compacting or dewatering of clays or oil sand tailings. However, not much attention has been paid to explore the effect of temperature on flocculating performance using thermal-sensitive polymers. In this study, poly(NIPAM-co-DMAPMA) was synthesized and employed to investigate the flocculating and re-flocculating performance of hydrophilic and hydrophobic particles at two specific temperatures; meanwhile settling and dewatering behaviors were also investigated. The results demonstrated that good flocculating performances were achieved at both room temperature (∼23 °C) and lower critical solution temperature (45 °C). Furthermore, larger flocs were formed at 45 °C as the copolymer was added. Floc strength and re-flocculating ability of the flocs were also intensified prominently at 45 °C. Additionally, settling and dewatering rates of suspensions were improved, and the moisture of filtered cakes was reduced when suspensions were at 45 °C. The phenomena could be justified by the phase transition of the copolymer from hydrophilicity to hydrophobicity as the temperature increased. There were much stronger adhesion forces between particles and higher adsorption amount of the copolymer onto solid surfaces at 45 °C. Therefore, the copolymer may be promising in solid-liquid separation to improve the floc size, floc strength, and settling and dewatering rate to achieve much lower moisture filtered cake.

  2. 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

  3. Wetting behavior on hybrid surfaces with hydrophobic and hydrophilic properties

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Chun-Wei [Dept. of Mechanical Engineering, Texas A and M University, College Station, TX 77843 (United States); Alvarado, Jorge L., E-mail: Alvarado@entc.tamu.edu [Dept. of Engineering Technology and Industrial Distribution, Texas A and M University, College Station, TX 77843 (United States); Marsh, Charles P. [ERDC – Construction Engineering Research Laboratory, 2902 Newmark Dr., Champaign, IL 61826 (United States); Dept. of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Champaign, IL 61801 (United States); Jones, Barclay G. [Dept. of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Champaign, IL 61801 (United States); Collins, Michael K. [ERDC – Construction Engineering Research Laboratory, 2902 Newmark Dr., Champaign, IL 61826 (United States); Dept. of Nuclear, Plasma, and Radiological Engineering, University of Illinois at Urbana-Champaign, Champaign, IL 61801 (United States)

    2014-01-30

    Hybrid surfaces consisting of a micropillar array of hydrophobic and hydrophilic sites were designed and fabricated to understand the effects of their unique surface morphology and chemistry on droplet condensation. Droplet impingement experiments have revealed that hybrid surfaces exhibit high contact angles, which is characteristic of purely hydrophobic surfaces. However, little is known about the wetting behavior of droplets that nucleate and grow on hybrid surfaces during condensation. In fact, condensed droplets display a distinct wetting behavior during the droplet growth phase which cannot be reproduced by simply impinging droplets on hybrid surfaces. In this study, hybrid surfaces with three different spacing ratios were subjected to condensation tests using an environmental scanning electron microscopy (ESEM) and a condensation cell under ambient conditions. For hybrid surfaces with spacing ratio below 2, droplets were observed to form on top and sides of the micropillars, where they grew, coalesced with adjacent droplets, and shed after reaching a given size. After shedding, the top surface remained partially dry, which allowed for immediate droplet growth. For hybrid surfaces with spacing ratio equal to 2, a different wetting behavior was observed, where droplets basically coalesced and formed a thin liquid film which was ultimately driven into the valleys of the microstructure. The liquid shedding process led to the renucleation of droplets primarily on top of the dry hydrophilic sites. To better understand the nature of droplet wetting on hybrid surfaces, a surface energy-based model was developed to predict the transition between the two observed wetting behaviors at different spacing ratios. The experimental and analytical results indicate that micropillar spacing ratio is the key factor for promoting different wetting behavior of condensed droplets on hybrid surfaces.

  4. Reactions at Solid Surfaces

    CERN Document Server

    Ertl, Gerhard

    2009-01-01

    Expanding on the ideas first presented in Gerhard Ertl's acclaimed Baker Lectures at Cornell University, Reactions at Solid Surfaces comprises an authoritative, self-contained, book-length introduction to surface reactions for both professional chemists and students alike. Outlining our present understanding of the fundamental processes underlying reactions at solid surfaces, the book provides the reader with a complete view of how chemistry works at surfaces, and how to understand and probe the dynamics of surface reactions. Comparing traditional surface probes with more modern ones, and brin

  5. Hydrophilic surface modification of acrylate-based biomaterials.

    Science.gov (United States)

    Arnal-Pastor, M; Comín-Cebrián, S; Martínez-Ramos, C; Monleón Pradas, M; Vallés-Lluch, A

    2016-04-01

    Acrylic polymers have proved to be excellent with regard to cell adhesion, colonization and survival, in vitro and in vivo. Highly ordered and regular pore structures thereof can be produced with the help of polyamide templates, which are removed with nitric acid. This treatment converts a fraction of the ethyl acrylate side groups into acrylic acid, turning poly(ethyl acrylate) scaffolds into a more hydrophilic and pH-sensitive substrate, while its good biological performance remains intact. To quantify the extent of such a modification, and be able to characterize the degree of hydrophilicity of poly(ethyl acrylate), poly(ethyl acrylate) was treated with acid for different times (four, nine and 17 days), and compared with poly(acrylic acid) and a 90/10%wt. EA/AAc copolymer (P(EA-co-AAc)). The biological performance was also assessed for samples immersed in acid up to four days and the copolymer, and it was found that the incorporation of acidic units on the material surface was not prejudicial for cells. This surface modification of 3D porous hydrophobic scaffolds makes easier the wetting with culture medium and aqueous solutions in general, and thus represents an advantage in the manageability of the scaffolds. © The Author(s) 2016.

  6. 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.

  7. Apparent activation energies associated with protein dynamics on hydrophobic and hydrophilic surfaces.

    Science.gov (United States)

    Langdon, Blake B; Kastantin, Mark; Schwartz, Daniel K

    2012-06-06

    With the use of single-molecule total internal reflection fluorescence microscopy (TIRFM), the dynamics of bovine serum albumin (BSA) and human fibrinogen (Fg) at low concentrations were observed at the solid-aqueous interface as a function of temperature on hydrophobic trimethylsilane (TMS) and hydrophilic fused silica (FS) surfaces. Multiple dynamic modes and populations were observed and characterized by their surface residence times and squared-displacement distributions (surface diffusion). Characteristic desorption and diffusion rates for each population/mode were generally found to increase with temperature, and apparent activation energies were determined from Arrhenius analyses. The apparent activation energies of desorption and diffusion were typically higher on FS than on TMS surfaces, suggesting that protein desorption and mobility were hindered on hydrophilic surfaces due to favorable protein-surface and solvent-surface interactions. The diffusion of BSA on TMS appeared to be activationless for several populations, whereas diffusion on FS always exhibited an apparent activation energy. All activation energies were small in absolute terms (generally only a few kBT), suggesting that most adsorbed protein molecules are weakly bound and move and desorb readily under ambient conditions. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  8. Hydrophobic/hydrophilic switching on zinc oxide micro-textured surface

    Science.gov (United States)

    Myint, Myo Tay Zar; Kumar, Nithin Senthur; Hornyak, Gabor Louis; Dutta, Joydeep

    2013-01-01

    Switchable wettability of zinc oxide (ZnO) microrod coated surfaces was controlled in two different ways: (1) by physical geometry (surface coverage area SA: the area covered by solid) and (2) by irradiation with ultraviolet (UV) light followed by infrared (IR) or furnace heating. In the first approach, the threshold coverage area for achieving hydrophobic surfaces was found to be <40%, which is in good agreement with predicted values in the literature leading to a metastable Cassie-Baxter regime. The transformation of hydrophobic to hydrophilic surfaces was studied by alternating cycles of 3 h exposure to ultraviolet (λpeak ∼ 253 nm) light followed by 1 h of annealing or IR irradiation alone. Three different annealing temperatures (120 °C, 200 °C and 250 °C) were utilized. Results of this work can be applied for designing surfaces with controlled wettability.

  9. 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.

  10. 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 ...

  11. Photochemistry on solid surfaces

    CERN Document Server

    Matsuura, T

    1989-01-01

    The latest developments in photochemistry on solid surfaces, i.e. photochemistry in heterogeneous systems, including liquid crystallines, are brought together for the first time in a single volume. Distinguished photochemists from various fields have contributed to the book which covers a number of important applications: molecular photo-devices for super-memory, photochemical vapor deposition to produce thin-layered electronic semiconducting materials, sensitive optical media, the control of photochemical reactions pathways, etc. Photochemistry on solid surfaces is now a major field and this

  12. Early osseointegration to hydrophilic and hydrophobic implant surfaces in humans.

    Science.gov (United States)

    Lang, Niklaus P; Salvi, Giovanni E; Huynh-Ba, Guy; Ivanovski, Saso; Donos, Nikolaos; Bosshardt, Dieter D

    2011-04-01

    To evaluate the rate and degree of osseointegration at chemically modified moderately rough, hydrophilic (SLActive) and moderately rough, hydrophobic (SLA) implant surfaces during early phases of healing in a human model. The devices used for this study of early healing were 4 mm long and 2.8 mm in diameter and had either an SLActive chemically modified or a moderately rough SLA surface configuration. These devices were surgically installed into the retro-molar area of 49 human volunteers and retrieved after 7, 14, 28 and 42 days of submerged healing. A 5.2-mm-long specially designed trephine with a 4.9 mm inside diameter, allowing the circumferential sampling of 1 mm tissue together with the device was applied. Histologic ground sections were prepared and histometric analyses of the tissue components (i.e. old bone, new bone, bone debris and soft tissue) in contact with the device surfaces were performed. All device sites healed uneventfully. All device surfaces were partially coated with bone debris. A significant fraction of this bone matrix coating became increasingly covered with newly formed bone. The process of new bone formation started already during the first week in the trabecular regions and increased gradually up to 42 days. The percentage of direct contact between newly formed bone and the device (bone-to-implant contact) after 2 and 4 weeks was more pronounced adjacent to the SLActive than to the SLA surface (14.8% vs. 12.2% and 48.3% vs. 32.4%, respectively), but after 42 days, these differences were no longer evident (61.6% vs. 61.5%). While healing showed similar characteristics with bone resorptive and appositional events for both SLActive and SLA surfaces between 7 and 42 days, the degree of osseointegration after 2 and 4 weeks was superior for the SLActive compared with the SLA surface. © 2011 John Wiley & Sons A/S.

  13. 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.

  14. Dissolution and solid-state characterization of poorly water-soluble drugs in the presence of a hydrophilic carrier.

    Science.gov (United States)

    Talukder, Rahmat; Reed, Chase; Dürig, Thomas; Hussain, Muhammad

    2011-12-01

    The aim of this study was to investigate the effects of a hydrophilic carrier on the solid-state and dissolution characteristics of poorly water-soluble drugs. Three poorly water-soluble drugs, ibuprofen, carbamazepine, and nifedipine, were studied in combination with hydroxypropyl cellulose (HPC), a low molecular weight hydrophilic polymer, without the use of solvent. A 1:1 drug-polymer ratio was used to evaluate the percent drug release, crystallinity, and wettability. A drug-polymer ratio of 1:4 was also used in co-grinding process to evaluate the effect of polymer levels on drug release. Dissolution studies were carried out in deionized water. Mean dissolution time (MDT) was calculated, and statistical analysis of MDTs was done following a single factor one-way analysis of variance. The dissolution rate of the drugs was enhanced by several folds by the simple process of co-grinding with HPC. X-ray diffraction studies were done to investigate the effects of physical and co-ground mix with HPC on the crystallinity of the drugs, which indicated a partial loss in crystallinity upon grinding. Differential scanning calorimetry studies were performed in order to identify possible solid-state interactions between the respective drugs and HPC. Wettability of the drugs by a 0.5% aqueous HPC solution was compared with that of water and n-hexane using the "Washburn method." Increased wetting and hydrophilization of the drugs by HPC, enlarged surface area due to particle size reduction, and a decrease in the degree of crystallinity were identified as the likely contributors to dissolution rate enhancement.

  15. 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...... of water droplets on silica surfaces offers a useful fundamental and quantitative measurement in order to study chemical and physical properties of water-silica systems. For hydrophobic systems the static and dynamic properties of the fluid-solid interface are influenced by the presence of air. Hence...

  16. 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.

  17. Attenuating Immune Response of Macrophage by Enhancing Hydrophilicity of Ti Surface

    Directory of Open Access Journals (Sweden)

    Xiaohan Dai

    2015-01-01

    Full Text Available Immune responses can determine the in vivo fate of implanted materials. The strategy for developing implants has shifted towards using materials with immunomodulatory activity. However, the immunoregulatory effect of hydrophilicity of titanium surface on the macrophage behavior and its underlying mechanism remain poorly understood. Here, the Ti surface hydrophilicity-dependent behavior of murine RAW264.7 macrophages was investigated in vitro. Two laboratory models with significantly different surface hydrophilicity and similar roughness were established with Ti-polished and Ti-H2O2 surfaces. The results of cell morphology observation showed that the Ti-H2O2 surface yielded enhanced cell adhesion and less multinucleated cell formation. CCK-8 assay indicated that the growth rate of macrophage on Ti-H2O2 surface is higher than that of Ti-polished. ELISA assay result revealed lower level of proinflammatory factor TNF-α and higher level of anti-inflammatory factor IL-10 on the Ti-H2O2 surface compared to Ti-polished. Subsequently, immunofluorescence and western blotting analysis showed that activation of the NF-κB-TNF-α pathway might be involved in the modulation of the immune response by surface hydrophilicity. Together, these results suggested that relative high hydrophilic Ti surface might attenuate the immune response of macrophage by activating NF-κB signaling. These findings could provide new insights into designing implant devices for orthopedic applications.

  18. Polypeptide friction and adhesion on hydrophobic and hydrophilic surfaces: a molecular dynamics case study.

    Science.gov (United States)

    Serr, Andreas; Horinek, Dominik; Netz, Roland R

    2008-09-17

    Using all-atomistic MD simulations including explicit water, the mobility and adhesion of a mildly hydrophobic single polypeptide chain adsorbed on hydrophobic and hydrophilic diamond surfaces is investigated by application of lateral and vertical pulling forces. Forced motion on the hydrophilic surface exhibits stick-slip due to breaking and reformation of hydrogen bonds; in contrast, on the hydrophobic surface, the motion is smooth. By carefully tuning the driving force magnitude, the linear-response regime is reached on a hydrophobic surface and equilibrium values for mobility and adhesive strength are obtained. On the hydrophilic surface, on the other hand, slow hydrogen-bond kinetics prevents equilibration and only upper bounds for adhesion force and mobility can be estimated. Whereas the desorption force is rather comparable on the two surfaces and differs at most by a factor of 2, the mobility on the hydrophilic surface is at least 30-fold reduced compared to the hydrophobic one. A simple model based on a single particle diffusing in a corrugated potential landscape suggests that cooperativity is rather limited and that the small mobility on a hydrophilic surface can be rationalized in terms of incoherently moving monomers. The experimentally well-known peptide mobility in bulk water is quantitatively reproduced in our simulations, which serves as a sensitive test on our methodology employed.

  19. Rapid, simple, and cost-effective treatments to achieve long-term hydrophilic PDMS surfaces

    Science.gov (United States)

    Hemmilä, Samu; Cauich-Rodríguez, Juan V.; Kreutzer, Joose; Kallio, Pasi

    2012-10-01

    This paper describes rapid, simple, and cost-effective treatments for producing biocompatible and long-term hydrophilic polydimethylsiloxane (PDMS) surfaces identified in an experimental study investigating 39 treatments in all. The wetting of the surfaces was monitored during six months. Changes in surface morphology and chemical composition were also analyzed. Some of the treatments are presented here for the first time, while for earlier presented treatments the selection of investigated parameters was wider and the observation period for the surface wetting longer. The PDMS surfaces were modified by surface activation, physisorption, and synthesis of both “grafting to” and “grafting from” polymer brushes. In surface activation, the PDMS sample was exposed to oxygen plasma, with several combinations of exposure time and RF power. In the physisorption and synthesis of polymer brushes, three commercially available and biocompatible chemicals were used: 2-hydroxyethyl methacrylate (HEMA), polyethylene glycol (PEG), and polyvinylpyrrolidone (PVP). Thirty-three of the 39 treatments rendered the PDMS hydrophilic, and in 12 cases the hydrophilicity lasted at least six months. Seven of these long-term hydrophilic coatings supported a contact angle of 30° or less. Three of the long-lasting hydrophilic coatings required only minutes to prepare.

  20. 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.

  1. 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

  2. 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.

  3. Adsorption of lipid liquid crystalline nanoparticles on cationic, hydrophilic, and hydrophobic surfaces.

    Science.gov (United States)

    Chang, Debby P; Jankunec, Marija; Barauskas, Justas; Tiberg, Fredrik; Nylander, Tommy

    2012-05-01

    Investigation of nonlamellar nanoparticles formed by dispersion of self-assembled lipid liquid crystalline phases is stimulated by their many potential applications in science and technology; resulting from their unique solubilizing, encapsulating, and space-dividing nature. Understanding the interfacial behavior of lipid liquid crystalline nanoparticles (LCNPs) at surfaces can facilitate the exploitation of such systems for a number of potentially interesting uses, including preparation of functional surface coatings and uses as carriers of biologically active substances. We have studied the adsorption of LCNP, based on phosphatidylcholine/glycerol dioleate and Polysorbate 80 as stabilizers, at different model surfaces by use of in situ ellipsometry. The technique allows time-resolved monitoring of the layer thickness and the amount adsorbed, thereby providing insights into the restructuring of the lipid nanoparticle upon adsorption. The effects of solvent condition, electrolyte concentration, particle size, and surface chemistry on adsorbed layer properties were investigated. Furthermore, the internal structures of the particles were investigated by cryo-transmission electron microscopy and small angle X-ray diffraction on the corresponding liquid crystalline phases in excess water. LCNPs are shown to form well-defined layers at the solid-liquid interface with a structure and coverage that are determined by the interplay between the self-assembly properties of the lipids and lipid surface interactions, respectively. At the hydrophobic surface, hydrophobic interaction results in a structural transition from the original LCNP morphology to a monolayer structure at the interface. In contrast, at cationic and hydrophilic surfaces, relaxation is a relatively slow process, resulting in much thicker adsorbed layers, with thickness and adsorption behavior that to a greater extent reflect the original bulk LCNP properties.

  4. Urea-formaldehyde monolithic column for hydrophilic in-tube solid-phase microextraction of aminoglycosides.

    Science.gov (United States)

    Wang, Jiabin; Zhao, Qi; Jiang, Nan; Li, Wenbang; Chen, Li; Lin, Xucong; Xie, Zenghong; You, Lijun; Zhang, Qiqing

    2017-02-17

    A novel urea-formaldehyde (UF) monolithic column has been developed and exploited as a sorbent for hydrophilic in-tube solid-phase microextraction (in-tube SPME) of aminoglycosides (AGs). Because of the innate hydrophilicity, UF monolith showed high extraction efficiency towards these hydrophilic analytes. The adsorption capacities for target compounds dissolved in water/ACN (1:1, v/v) were in the range of 5.18-7.36μg/cm. Due to the lack of a chromophore, evaporative light scattering detector (ELSD) was selected as the detector for AGs, and coupled with the online in-tube SPME-HPLC system. Several factors of the online system, such as trifluoroacetic acid (TFA) and ACN percentage in the sampling solution, ionic strength in the sample solution, elution volume, sampling and elution flow rate, were optimized with respect to the extraction efficiencies. Under the optimized conditions, the limits of detection (LODs) of streptomycin, tobramycin and neomycin were discovered in the range of 3.0-5.2μg/kg. The recoveries were ranged from 82.1 to 96.7% with relative standard deviations (RSDs) of 2.3-5.1% (n=4) at spiking levels of 50, 200 and 500μg/kg, respectively. The excellent applicability of the UF monolithic column was examined by the determination of streptomycin in practical tilapia samples, which showed the potential advantages for the analysis of polar analytes in complicated samples. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    OpenAIRE

    Rotenberg, Benjamin; Patel, Amish J.; 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 surf...

  6. Sodium hyaluronate-functionalized urea-formaldehyde monolithic column for hydrophilic in-tube solid-phase microextraction of melamine.

    Science.gov (United States)

    Wang, Jiabin; Jiang, Nan; Cai, Zhengmiao; Li, Wenbang; Li, Jianhua; Lin, Xucong; Xie, Zenghong; You, Lijun; Zhang, Qiqing

    2017-09-15

    A novel sodium hyaluronate-functionalized urea-formaldehyde (UF) monolithic column has been developed by in-situ polycondensation of urea, formaldehyde and sodium hyaluronate (HA). HA plays both the roles of crosslinking and hydrophilic functionalization. The preparation factors including different molecular weights of HA and different amounts of HA were optimized, and then a uniform monolith with satisfactory permeability and hydrophilic binding capacity was obtained. Due to the excellent hydrophilicity of HA, HA-functionalized UF monolith showed higher hydrophilic extraction efficiency than UF monolith, and was applied for hydrophilic in-tube solid-phase microextraction (SPME) of melamine (MEL). Several factors for hydrophilic in-tube SPME, such as ACN percentage in the sampling solution, salt concentration and pH value of the sampling solution, elution volume, sampling and elution flow rate, were investigated with respect to the extraction efficiency of MEL. Under the optimized SPME conditions, the limit of detection (LOD) of MEL was found to be 0.2ng/mL in the milk formula samples, the recoveries of MEL spiked in milk formula samples ranged from 87.3% to 96.7% with relative standard deviations (RSDs) less than 5.1%. Owing to the excellent hydrophilic extraction ability, the novel HA-functionalized UF monolith could provide a promising tool for the sensitive analysis of polar analytes in complicated samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Osteogenic response of human MSCs and osteoblasts to hydrophilic and hydrophobic nanostructured titanium implant surfaces.

    Science.gov (United States)

    Lotz, Ethan M; Olivares-Navarrete, Rene; Berner, Simon; Boyan, Barbara D; Schwartz, Zvi

    2016-12-01

    Microstructured implant surfaces created by grit blasting and acid etching titanium (Ti) support osseointegration. This effect is further enhanced by storing in aqueous solution to retain hydrophilicity, but this also leads to surface nanostructure formation. The purpose of this study was to assess the contributions of nanostructures on the improved osteogenic response of osteoblast lineage cells to hydrophilic microstructured Ti. Human mesenchymal stem cells (MSCs) and normal human osteoblasts (NHOsts) were cultured separately on non-nanostructured/hydrophobic (SLA), nanostructured/hydrophilic (modSLA), or nanostructured/hydrophobic (SLAnano) Ti surfaces. XPS showed elevated carbon levels on SLA and SLAnano compared to modSLA. Contact angle measurements indicated only modSLA was hydrophilic. Confocal laser microscopy revealed minor differences in mean surface roughness. SEM showed the presence of nanostructures on modSLA and SLAnano. MSCs and NHOst cells exhibited similar morphology on the substrates and osteoblastic differentiation and maturation were greatest on modSLA. These results suggest that when the appropriate microstructure is present, hydrophilicity may play a greater role in stimulating MSC and NHOst osteoblastic differentiation and maturation than the presence of nanostructures generated during storage in an aqueous environment. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 3137-3148, 2016. © 2016 Wiley Periodicals, Inc.

  8. Characterization of solid surfaces

    National Research Council Canada - National Science Library

    Kane, Philip F; Larrabee, Graydon B

    1974-01-01

    .... A comprehensive review of surface analysis, this important volume surveys both principles and techniques of surface characterization, describes instrumentation, and suggests the course of future research...

  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

    -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...... 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...... at both surfaces. The ordering is characteristically different between the surfaces and of longer range at the hydrophilic surface. Furthermore, the dynamic properties of water are different at the two surfaces and different from the bulk behavior. In particular, at the hydrophobic surface, time...

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

    Energy Technology Data Exchange (ETDEWEB)

    Mertens, M., E-mail: michael.mertens@uni-ulm.de [Institute of Micro and Nanomaterials, Ulm University, 89081 Ulm (Germany); Mohr, M.; Brühne, K.; Fecht, H.J. [Institute of Micro and Nanomaterials, Ulm University, 89081 Ulm (Germany); Łojkowski, M.; Święszkowski, W. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Warsaw (Poland); Łojkowski, W. [Institute of High Pressure Physics, Polish Academy of Sciences, Warsaw (Poland)

    2016-12-30

    Highlights: • Hydrophobic and hydrophilic properties on fluorine-, hydrogen- and oxygen- terminated ultra-nanocrystalline diamond films. • Micropatterned - multi-terminated layers with both hydrophobic and hydrophilic areas on one sample. • Visualization of multi-terminated surfaces by e.g. SEM and LFM. • Roughness and friction investigations on different terminated surfaces. • Smooth and biocompatible surfaces with same roughness regardless of hydrophobicity for microbiological investigations. - Abstract: 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

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

    Science.gov (United States)

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

    2016-09-06

    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.

  12. 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. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.

  13. 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.

  14. Static and Dynamic Wetting Behavior of Triglycerides on Solid Surfaces.

    Science.gov (United States)

    Michalski; Saramago

    2000-07-15

    Triglyceride wetting properties on solid surfaces of different hydro-phobicities were investigated using three different methods, namely, the sessile drop method for static contact angle measurements, the Wilhelmy method for dynamic contact angle measurements, and the captive bubble method to investigate thin triglyceride film stability. For solid surfaces having a surface free energy higher than the surface tension of triglycerides (tributyrin, tricaprylin, and triolein), a qualitative correlation was observed between wetting and solid/triglyceride relative hydrophobicities. On surfaces presenting extreme hydrophobic or hydrophilic properties, medium-chain triglycerides had a behavior similar to that of long-chain unsaturated ones. On a high-energy surface (glass), tricaprylin showed an autophobic effect subsequent to molecular adsorption in trident conformation on the solid, observed with the three methods. Thin triglyceride films between an air bubble and a solid surface were stable for a short time, for solids with a surface free energy larger than the triglyceride surface tension. If the solid surface had a lower surface free energy, the thin film collapsed after a time interval which increased with triglyceride viscosity. Copyright 2000 Academic Press.

  15. Interfacial water at hydrophobic and hydrophilic surfaces: slip, viscosity, and diffusion.

    Science.gov (United States)

    Sendner, Christian; Horinek, Dominik; Bocquet, Lyderic; Netz, Roland R

    2009-09-15

    The dynamics and structure of water at hydrophobic and hydrophilic diamond surfaces is examined via non-equilibrium Molecular Dynamics simulations. For hydrophobic surfaces under shearing conditions, the general hydrodynamic boundary condition involves a finite surface slip. The value of the slip length depends sensitively on the surface water interaction strength and the surface roughness; heuristic scaling relations between slip length, contact angle, and depletion layer thickness are proposed. Inert gas in the aqueous phase exhibits pronounced surface activity but only mildly increases the slip length. On polar hydrophilic surfaces, in contrast, slip is absent, but the water viscosity is found to be increased within a thin surface layer. The viscosity and the thickness of this surface layer depend on the density of polar surface groups. The dynamics of single water molecules in the surface layer exhibits a similar distinction: on hydrophobic surfaces the dynamics is purely diffusive, while close to a hydrophilic surface transient binding or trapping of water molecules over times of the order of hundreds of picoseconds occurs. We also discuss in detail the effect of the Lennard-Jones cutoff length on the interfacial properties.

  16. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jaehyun; Hwang, Sangyeon; Cho, Dae-Hyun [Department of Mechanical Engineering, Sungkyunkwan University, Suwon 16419 (Korea, Republic of); Hong, Jungwoo [Department of Mechanical Engineering, Graduate of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141 (Korea, Republic of); Shin, Jennifer H., E-mail: j_shin@kaist.ac.kr [Department of Mechanical Engineering, Graduate of Medical Science and Engineering, Korea Advanced Institute of Science and Technology, Daejeon 34141 (Korea, Republic of); Byun, Doyoung, E-mail: dybyun@skku.edu [Department of Mechanical Engineering, Sungkyunkwan University, Suwon 16419 (Korea, Republic of)

    2017-02-01

    Highlights: • Simple and amenable reforming method for a substrate with disparate patterns of hydrophilic dots on super-hydrophobic surfaces is proposed. • Wettability characteristics and modification mechanism for the surfaces are conducted and revealed through SEM, AFM, WSI, and SIMS. • Several representative materials for various applications are successfully deposited. - Abstract: 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.

  18. Comparison of the Fouling Release Properties of Hydrophobic Fluorinated and Hydrophilic PEGylated Block Copolymer Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Krishnan,S.; Wang, N.; Ober, C.; Finlay, J.; Callow, M.; Callow, J.; Hexemer, A.; Sohn, K.; Kramer, E.; Fischer, D.

    2006-01-01

    To understand the role of surface wettability in adhesion of cells, the attachment of two different marine algae was studied on hydrophobic and hydrophilic polymer surfaces. Adhesion of cells of the diatom Navicula and sporelings (young plants) of the green macroalga Ulva to an underwater surface is mainly by interactions between the surface and the adhesive exopolymers, which the cells secrete upon settlement and during subsequent colonization and growth. Two types of block copolymers, one with poly(ethylene glycol) side-chains and the other with liquid crystalline, fluorinated side-chains, were used to prepare the hydrophilic and hydrophobic surfaces, respectively. The formation of a liquid crystalline smectic phase in the latter inhibited molecular reorganization at the surface, which is generally an issue when a highly hydrophobic surface is in contact with water. The adhesion strength was assessed by the fraction of settled cells (Navicula) or biomass (Ulva) that detached from the surface in a water flow channel with a wall shear stress of 53 Pa. The two species exhibited opposite adhesion behavior on the same sets of surfaces. While Navicula cells released more easily from hydrophilic surfaces, Ulva sporelings showed higher removal from hydrophobic surfaces. This highlights the importance of differences in cell-surface interactions in determining the strength of adhesion of cells to substrates.

  19. 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.

  20. Influence of roughness on capillary forces between hydrophilic surfaces

    NARCIS (Netherlands)

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

    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

  1. 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...

  2. Hydrophilic Surface Modification of PDMS Microchannel for O/W and W/O/W Emulsions

    Directory of Open Access Journals (Sweden)

    Shazia Bashir

    2015-09-01

    Full Text Available A surface modification method for bonded polydimethylsiloxane (PDMS microchannels is presented herein. Polymerization of acrylic acid was performed on the surface of a microchannel using an inline atmospheric pressure dielectric barrier microplasma technique. The surface treatment changes the wettability of the microchannel from hydrophobic to hydrophilic. This is a challenging task due to the fast hydrophobic recovery of the PDMS surface after modification. This modification allows the formation of highly monodisperse oil-in-water (O/W droplets. The generation of water-in-oil-in-water (W/O/W double emulsions was successfully achieved by connecting in series a hydrophobic microchip with a modified hydrophilic microchip. An original channel blocking technique to pattern the surface wettability of a specific section of a microchip using a viscous liquid comprising a mixture of honey and glycerol, is also presented for generating W/O/W emulsions on a single chip.

  3. 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.

  4. Adsorption and diffusion of plasma proteins on hydrophilic and hydrophobic surfaces: effect of trifluoroethanol on protein structure.

    Science.gov (United States)

    Vieira, Euridice P; Rocha, Sandra; Carmo Pereira, M; Möhwald, Helmuth; Coelho, Manuel A N

    2009-09-01

    The aim of this work was to investigate the conformational changes and diffusion of adsorbed proteins (immunoglobulin G (IgG), fibrinogen (Fib) and human serum albumin (HSA)) on hydrophilic quartz and hydrophobized quartz (octadecyltrichlorosilane (OTS)) surfaces. Circular dichroism spectroscopy measurements have shown that IgG is the most stable protein after adsorption on hydrophilic quartz, whereas HSA and Fib unfold. The structural changes are dependent on adsorption time, initial protein concentration in bulk, and surface chemistry. The effect of trifluoroethanol (TFE) in recovering the original protein structure after adsorption was analyzed by total internal reflection fluorescence and fluorescence recovery after photobleaching (TIRF-FRAP). TIRF-FRAP experiments revealed a strong dependence of the surface chemistry on protein diffusion coefficients: proteins diffuse 4 times slower on hydrophobic surfaces than on hydrophilic surfaces. The diffusion coefficient of TFE at hydrophobic surfaces is 2 orders magnitude higher than at hydrophilic surfaces. However, protein desorption occurs faster on hydrophilic quartz than on OTS, proving that the strength of protein-surface interaction is weaker at hydrophilic surfaces. This result shows that desorption is determined by surface/protein chemistry and not by mass transfer limitations. FTIR-ATR results demonstrated that TFE interaction with adsorbed proteins is stronger at hydrophilic surfaces than at hydrophobic surfaces.

  5. Interactions between a polystyrene particle and hydrophilic and hydrophobic surfaces in aqueous solutions.

    Science.gov (United States)

    Thormann, Esben; Simonsen, Adam C; Hansen, Per L; Mouritsen, Ole G

    2008-07-15

    The interaction between a colloidal polystyrene particle mounted on an AFM cantilever and a hydrophilic and a hydrophobic surface in aqueous solution is investigated. Despite the apparent simplicity of these two types of systems a variety of different types of interactions are observed. The system containing the polystyrene particle and a hydrophilic surface shows DLVO-like interactions characteristic of forces between charged surfaces. However, when the surface is hydrophobized the interaction changes dramatically and shows evidence of a bridging air bubble being formed between the particle and the surface. For both sets of systems, plateaus of constant force in the force curves are obtained when the particle is retracted from the surface after being in contact. These events are interpreted as a number of individual polystyrene molecules that are bridging the polystyrene particle and the surface. The plateaus of constant force are expected for pulling a hydrophobic polymer in a bad (hydrophilic) solvent. The plateau heights are found to be of uniform spacing and independent of the type of surface, which suggests a model by which collapsed polymers are extended into the aqueous medium. This model is supported by a full stretching curve showing also the backbone elasticity and a stretching curve obtained in pentanol, where the plateau changes to a nonlinear force response, which is typical for a polymer in a good or neutral solvent. We suggest that these polymer bridges are important in particular for the interaction between polystyrene and the hydrophilic surface, where they to some extent counteract the long-range electrostatic repulsion.

  6. 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.

  7. 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........ The contact angle of SU-8 surface was significantly reduced from 90° to 25° after the surface modification. The treated SU-8 surfaces provided a cell culture environment that was comparable with cell culture flask surface in terms of generation time and morphology....

  8. Attractive double-layer forces between neutral hydrophobic and neutral hydrophilic surfaces.

    Science.gov (United States)

    Lima, Eduardo R A; Boström, Mathias; Schwierz, Nadine; Sernelius, Bo E; Tavares, Frederico W

    2011-12-01

    The interaction between surface patches of proteins with different surface properties has a vital role to play driving conformational changes in proteins in different salt solutions. We demonstrate the existence of ion-specific attractive double-layer forces between neutral hydrophobic and hydrophilic surfaces in the presence of certain salt solutions. This is performed by solving a generalized Poisson-Boltzmann equation for two unequal surfaces. In the calculations, we utilize parametrized ion-surface potentials and dielectric-constant profiles deduced from recent non-primitive-model molecular dynamics simulations that partially account for molecular structure and hydration effects.

  9. Surface hydration drives rapid water imbibition into strongly hydrophilic nanopores.

    Science.gov (United States)

    Fang, Chao; Qiao, Rui

    2017-08-09

    The imbibition of liquids into nanopores plays a critical role in numerous applications, and most prior studies focused on imbibition due to capillary flows. Here we report molecular simulations of the imbibition of water into single mica nanopores filled with pressurized gas. We show that, while capillary flow is suppressed by the high gas pressure, water is imbibed into the nanopore through surface hydration in the form of monolayer liquid films. As the imbibition front moves, the water film behind it gradually densifies. Interestingly, the propagation of the imbibition front follows a simple diffusive scaling law. The effective diffusion coefficient of the imbibition front, however, is more than ten times larger than the diffusion coefficient of the water molecules in the water film adsorbed on the pore walls. We clarify the mechanism for the rapid water imbibition observed here.

  10. Highly efficient solid-phase derivatization of sugar phosphates with titanium-immobilized hydrophilic polydopamine-coated silica.

    Science.gov (United States)

    Qin, Qian; Wang, Bohong; Chang, Mengmeng; Zhou, Zhihui; Shi, Xianzhe; Xu, Guowang

    2016-07-29

    Sugar phosphates are a type of key metabolic intermediates of glycolysis, gluconeogenesis and pentose phosphate pathway, which can regulate tumor energetic metabolism. Due to their low endogenous concentrations, poor chromatographic retention properties as well as ionization suppression from complex matrix interference, the determination of sugar phosphates in biological samples is very difficult. In this study, titanium-immobilized hydrophilic polydopamine-coated silica microspheres (SiO2@PD-Ti(4+)) were synthesized for highly efficient solid-phase derivatization of sugar phosphates. Sugar phosphates were selectively captured onto the surface of the SiO2@PD-Ti(4+) microspheres by chelating with phosphate groups, and then reacted with 3-amino-9-ethylcarbazole via reductive amination based on solid-phase derivatization, which could not only increase the retention and resolution of sugar phosphates on reversed-phase liquid chromatography (RPLC), but also improve the mass spectrometry (MS) sensitivity of sugar phosphates. The adsorption capacity of SiO2@PD-Ti(4+) microspheres towards glucose-6-phosphate is 0.76mg/g, which is much larger than that of commercial TiO2. Compared with the traditional liquid-phase derivatization, the solid-phase derivatization based on the SiO2@PD-Ti(4+) microspheres displayed several superiorities including shorter derivatization time (within 10min), higher product purity and much lower limit of detection (up to 38pmol/L). In addition, good linearity (R(2)≥0.99), excellent recovery (80.6-118%) and high precision (RSDs with 2.8-7.8%) were obtained when the developed method was used for quantitative analysis of sugar phosphates. Finally, the SiO2@PD-Ti(4+) microspheres combined with RPLC-MS were successfully applied to the determination of sugar phosphates from hepatocarcinoma cell lines and could even detect the trace sugar phosphates in thousands of cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. In vitro evaluation of iris chafe protection afforded by hydrophilic surface modification of polymethylmethacrylate intraocular lenses.

    Science.gov (United States)

    Hofmeister, F M; Yalon, M S; Iida, S; Goldberg, M D

    1988-09-01

    An in vitro iris chafe test was developed to evaluate possible differences in abrasive interaction of various intraocular lens (IOL) materials with the posterior surface of the iris. The materials that were compared in initial tests with rabbit irides were high molecular weight polymethylmethacrylate (PMMA), the primary IOL material in current use, and surface-modified PMMA, which had a permanent, chemically bound, hydrophilic, polymer surface. Scanning electron microscopy, light microscopy, and examination of histological sections were used to assess tissue damage. A "window defect" type of abrasive damage was observed by light microscopy for PMMA lenses and is very similar in appearance to that seen for iris abrasion by human implants when viewed in vivo in slitlamp examinations. Results for both pigmented and albino rabbit irides indicate a reduction in abrasive insult to the external iris basement membrane and underlying pigment epithelium by the hydrophilic surface modification of PMMA. These results are consistent with our observation of a major reduction in corneal endothelium damage on contact with the hydrophilic surface-modified PMMA as compared with PMMA itself. This in vitro iris abrasion test, therefore, appears to be a useful technique for future evaluation of IOL surface properties.

  12. 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.

  13. Molecular tailoring of solid surfaces

    CERN Document Server

    Evenson, S A

    1997-01-01

    The overall performance of a material can be dramatically improved by tailoring its surface at the molecular level. The aim of this project was to develop a universal technique for attaching dendrimers (well-defined, nanoscale, functional polymers) and Jeffamines (high molecular weight polymer chains) to the surface of any shaped solid substrate. This desire for controlled functionalization is ultimately driven by the need to improve material compatibility in various biomedical applications. Atomic force microscopy (AFM) was used initially to study the packing and structure of Langmuir-Blodgett films on surfaces, and subsequently resulted in the first visualization of individual, spherically shaped, nanoscopic polyamidoamine dendrimers. The next goal was to develop a methodology for attaching such macromolecules to inert surfaces. Thin copolymer films were deposited onto solid substrates to produce materials with a fixed concentration of surface anhydride groups. Vapor-phase functionalization reactions were t...

  14. 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...

  15. 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 hydrophobic attraction of the untreated PS-PS system to pure repulsion between untreated PS and treated PS, demonstrating the important role of surface hydrophobicity on the formation and stability of bubbles on substrates. Our results indicate that DLVO 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.

  16. Using pollen grains as novel hydrophilic solid-phase extraction sorbents for the simultaneous determination of 16 plant growth regulators.

    Science.gov (United States)

    Lu, Qian; Wu, Jian-Hong; Yu, Qiong-Wei; Feng, Yu-Qi

    2014-11-07

    In this article, pollen grains were for the first time used as a hydrophilic solid-phase extraction (HILIC-SPE) sorbent for the determination of 16 plant growth regulators (PGRs) in fruits and vegetables. Fourier transform infrared spectroscopy (FT-IR), scanning electronic microscopy (SEM) and nitrogen sorption porosimetry (NSP) were used to investigate the chemical structure and the surface properties of the pollen grains. Pollen grains exhibited an excellent adsorption capacity for some polar compounds due to their particular functional groups. Several parameters influencing extraction performance were investigated. A green and simple HILIC-SPE-method using pollen grain cartridge for purification of fruit and vegetable extractions, followed by ultra-high performance liquid chromatography-triple quadrupole tandem mass spectrometry (UHPLC-MS/MS) was established. Good linear relationships were obtained for 16 PGRs with correlation coefficients (R) above 0.9980. The limits of detection (LODs) of 16 PGRs in cucumber were in the range of 0.01-1.10 μg · kg(-1). Reproducibility of the method was evaluated by intra-day and inter-day precisions with relative standard deviations (RSDs), which were less than 14.4%. We successfully applied this methodology to analyze 16 PGRs in 8 different kinds of fruits and vegetables. The recoveries from samples spiked with 16 PGRs were from 80.5% to 119.2%, with relative standard deviations less than 15.0%. Copyright © 2014 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    Kanduč, Matej; Netz, Roland R

    2015-10-06

    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.

  18. Method of making a membrane having hydrophilic and hydrophobic surfaces for adhering cells or antibodies by using atomic oxygen or hydroxyl radicals

    Science.gov (United States)

    Koontz, Steven L. (Inventor); Spaulding, Glenn F. (Inventor)

    1994-01-01

    A portion of an organic polymer article such as a membrane is made hydrophilic by exposing a hydrophobic surface of the article to a depth of about 50 to about 5000 angstroms to atomic oxygen or hydroxyl radicals at a temperature below 100C., preferably below 40 C, to form a hydrophilic uniform surface layer of hydrophilic hydroxyl groups. The atomic oxygen and hydroxyl radicals are generated by a flowing afterglow microwave discharge, and the surface is outside of a plasma produced by the discharge. A membrane having both hydrophilic and hydrophobic surfaces can be used in an immunoassay by adhering antibodies to the hydrophobic surface. In another embodiment, the membrane is used in cell culturing where cells adhere to the hydrophilic surface. Prior to adhering cells, the hydrophilic surface may be grafted with a compatibilizing compound. A plurality of hydrophilic regions bounded by adjacent hydrophobic regions can be produced such that a maximum of one cell per each hydrophilic region adheres.

  19. Study of Hydrophobic and Ionizable Hydrophilic Copolymers at Polymer/Solid and Polymer/Liquid Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Perahia, Dvora

    2011-11-01

    Joint experimental-computational efforts were set to characterize the interfacial effects on the structure and dynamics of polymers consisting of highly rigid hydrophilic-ionizable and hydrophobic sub-units within one polymeric chain casted into thin films of several molecular dimensions. Focusing on the ultra thin film region we separate out the interfacial effects from bulk characteristics. Specifically, the study sought to: identify the parameters that control the formation of a stable polymer-solid interface. The study consists of two components, experimental investigations and computational efforts. The experimental component was designed to derive empirical trends that can be used to correlate the set of coupled polymer molecular parameters with the interfacial characteristics of these polymers, and their response to presence of solvents. The computational study was designed to provide molecular insight into the ensemble averages provided by the experimental efforts on multiple length scales from molecular dimensions, to the nanometer lengths to a macroscopic understanding of solvent interactions with structured polymers. With the ultimate goal of correlating molecular parameters to structure, dynamics and properties of ionic polymers, the first stage of the research began with the study of two systems, one which allowed tailoring the flexibility of the backbone without the presence of ionic groups, but with a potential to sulfonate groups at a later stage, and a polymer whose backbone is rigid and the density of the ionic group can be varied. The combined experimental and computational studies significantly extended the understanding of polymers at interfaces from model systems to polydispersed copolymers with blocks of varying nature and complexity. This new insight directly affects the design of polymers for sustainable energy applications from batteries and fuel cells to solar energy.

  20. Influence of glycosylation on the adsorption of Thermomyces lanuginosus lipase to hydrophobic and hydrophilic surfaces.

    Science.gov (United States)

    Pinholt, Charlotte; Fanø, Mathias; Wiberg, Charlotte; Hostrup, Susanne; Bukrinsky, Jens Thostrup; Frokjaer, Sven; Norde, Willem; Jorgensen, Lene

    2010-07-11

    In the pharmaceutical industry, protein drugs are modified by, for instance, glycosylation in order to obtain protein drugs with improved delivery profiles and/or increased stability. The effect of glycosylation on protein adsorption behaviour is one of the stability aspects that must be evaluated during development of glycosylated protein drug products. We have studied the effect of glycosylation on the adsorption behaviour of Thermomyces lanuginosus lipase to hydrophobic and hydrophilic surfaces using total internal reflection fluorescence, surface plasmon resonance, far-UV circular dichroism and fluorescence. Three glyco-variants were used, namely the mono-glycosylated wildtype T. lanuginosus lipase, a non-glycosylated variant and a penta-glycosylated variant, the latter two containing one and nine amino acid substitutions, respectively. All the glycosylations were N-linked and contained no charged sugar residues. Glycosylation did not affect the adsorption of wildtype T. lanuginosus lipase to the hydrophobic surfaces. The number of molecules adsorbing per unit surface area, the structural changes occurring upon adsorption, and the orientation upon adsorption were found to be unaffected by the varying glycosylation. However, the interaction with a hydrophilic surface was different between the three glyco-variants. The penta-glycosylated T. lanuginosus lipase adsorbed, in contrast to the two other glyco-variants. In conclusion, adsorption of T. lanuginosus lipase to hydrophobic surfaces was not affected by N-linked glycosylation. Only penta-glycosylated T. lanuginosus lipase adsorbed to the hydrophilic surface, apparently due to its increased net charge of +3 caused by amino acid substitutions in the primary sequence. 2010 Elsevier B.V. All rights reserved.

  1. Early bone apposition to hydrophilic and hydrophobic titanium implant surfaces: a histologic and histomorphometric study in minipigs.

    Science.gov (United States)

    Vasak, Christoph; Busenlechner, Dieter; Schwarze, Uwe Y; Leitner, Herbert F; Munoz Guzon, Fernando; Hefti, Thomas; Schlottig, Falko; Gruber, Reinhard

    2014-12-01

    The first objective of this pilot study was to evaluate the impact of the hydrophilicity on the early phases of osseointegration. The second objective was to compare two hydrophilic implant surfaces with different geometries, surface roughness, and technologies achieving hydrophilicity. Twelve weeks after extraction, all four quadrants of nine minipigs received three dental implants, alternating between hydrophilic microrough surfaces (INICELL and SLActive) and a conventional hydrophobic microrough surface. After 5, 10, and 15 days of submerged healing, ground sections were prepared and subjected to histologic and histomorphometric analysis. The histologic analysis revealed a similar healing pattern among the hydrophilic and hydrophobic implant surfaces, with extensive bone formation occurring between day 5 and day 10. With BIC values of greater than 50% after 10 days, all examined surfaces indicated favorable osseointegration at this very early point in healing. At day 15, the mean new bone-to-implant contact (newBIC) of one hydrophilic surface (INICELL; 55.8 ± 14.4%) was slightly greater than that of the hydrophobic microrough surface (40.6 ± 20.2%). At day 10 and day 15, an overall of 21% of the implants had to be excluded from analysis due to inflammations primarily caused by surgical complications. Substantial bone apposition occurs between day 5 and day 10. The data suggest that the hydrophilic surface can provoke a slight tendency toward increased bone apposition in minipigs after 15 days. A direct comparison of two hydrophilic surfaces with varying geometries is of limited relevance. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  2. 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...

  3. 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

    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...... 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...

  4. 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...... angle measurements and XPS. Moreover, ATR FTIR has been used to confirm the formation of initiating groups. Grafting of PEGMA from PEEK was performed in aqueous solution. The presence of the PPEGMA grafts on PEEK was revealed by the thermograms from TGA whereas investigations with AFM rejected changes...

  5. 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

  6. Hydrophilic monolayer formation of adsorbed cationic starch and cationic hydroxyethyl cellulose derivatives on polyester surfaces.

    Science.gov (United States)

    Roos, Peter; Westling, Asa; Chronakis, Ioannis S

    2004-11-01

    Cationic starch, cationic cellulose derivatives, and hydrophobically modified cationic cellulose were physically adsorbed from aqueous solution onto oppositely charged hydrophobic polyester (poly(ethylene terephthalate)) fabric and nonwoven, and this resulted in hydrophilic surface properties. Surface coverage of the polysaccharides occurred primarily by strong electrostatic interactions, and the surface characteristics were evaluated by measuring the time required for a water droplet to be absorbed into the polyester material as well as by electron spectroscopy for chemical analysis (ESCA). From a comparison of the adsorption characteristics we assess the polysaccharide-dependent and substrate-dependent adsorption behavior and discuss the similarities and differences in the hydrophilic properties and wettability observed. In particular, the temperature of the cationic polysaccharide solutions in which the substrate was immersed, the configuration of the polymer in solution, and the presence of hydrophobic substituents on the cationic moiety have a considerable effect on the polysaccharide affinity and its adsorption on the surface, irrespective of the substrate type (fabric or nonwoven). We also evaluate the relative contribution of the polyelectrolyte molecular weight, concentration in solution, and degree of charge density along the polymer chain which determine the range of interactions and alter surface hydroplilicity dependent on the type of substrate.

  7. Effects of hydrophilicity/lipophilicity of nano-TiO2 on surface tension of TiO2-water nanofluids

    Science.gov (United States)

    Zhang, Shenghan; Han, Xiaoxue; Tan, Yu; Liang, Kexin

    2018-01-01

    Platinum plate method based on Wilhelmy plate was used to measure the surface tension of hydrophilic nano-titanium dioxide-deionized water (nano-TiO2- DIW) fluids and hydrophilic lipophilic nano-TiO2-DIW fluids. Experimental results show that the surface adsorption of hydrophilic lipophilic nano-TiO2 is positive adsorption, and hydrophilic nano-TiO2 is negative adsorption. The hydrophilic nano-TiO2 in deionized water increases the surface tension of base fluid, and hydrophilic lipophilic nano-TiO2 in deionized water decreases. The surface tension of hydrophilic TiO2-DIW nanofluids increases, and hydrophilic lipophilic TiO2-DIW nanofluids decreases linearly with an increase in the natural logarithm of the molar concentration of nanofluids.

  8. 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.

  9. Controlling the hydrophilicity and contact resistance of fuel cell bipolar plate surfaces using layered nanoparticle assembly

    Science.gov (United States)

    Wang, Feng

    Hybrid nanostructured coatings exhibiting the combined properties of electrical conductivity and surface hydrophilicity were obtained by using Layer-by-Layer (LBL) assembly of cationic polymer, silica nanospheres, and carbon nanoplatelets. This work demonstrates that by controlling the nanoparticle zeta (zeta) potential through the suspension parameters (pH, organic solvent type and amount, and ionic content) as well as the assembly sequence, the nanostructure and composition of the coatings may be adjusted to optimize the desired properties. Two types of silica nanospheres were evaluated as the hydrophilic component: X-TecRTM 3408 from Nano-X Corporation, with a diameter of about 20 nm, and polishing silica from Electron Microscopy Supply, with diameter of about 65 nm. Graphite nanoplatelets with a thickness of 5~10nm (Aquadag RTM E from Acheson Industries) were used as electrically conductive filler. A cationic copolymer of acrylamide and a quaternary ammonium salt (SuperflocRTM C442 from Cytec Corporation) was used as the binder for the negatively charged nanoparticles. Coatings were applied to gold-coated stainless steel substrates presently used a bipolar plate material for proton exchange membrane (PEM) fuel cells. Coating thickness was found to vary nearly linearly with the number of polymer-nanoparticle layers deposited while a monotonic increase in coating contact resistance was observed for all heterogeneous and pure silica coatings. Thickness increased if the difference in the oppositely charged zeta potentials of the adsorbing components was enhanced through alcohol addition. Interestingly, an opposite effect was observed if the zeta potential difference was increased through pH variation. This previously undocumented difference in adsorption behavior is herein related to changes to the surface chemical heterogeneity of the nanoparticles. Coating contact resistance and surface wettability were found to have a more subtle dependence on the assembly

  10. 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.

  11. Fast and Simple Preparation of Patterned Surfaces with Hydrophilic Polymer Brushes by Micromolding in Capillaries.

    Science.gov (United States)

    Vonhören, Benjamin; Langer, Marcel; Abt, Doris; Barner-Kowollik, Christopher; Ravoo, Bart Jan

    2015-12-22

    Micropatterns of hydrophilic polymer brushes were prepared by micromolding in capillaries (MIMIC). The polymers are covalently bound to the surfaces by a rapid hetero Diels-Alder reaction, constituting the first example of polymers grafted to surfaces in a defined pattern by MIMIC. The polymers [poly(acrylic acid), poly(hydroxyethyl acrylate), and poly(tetraethylene glycol acrylate) ranging in molecular weight from 1500 to 6000 g mol(-1)] were prepared with narrow dispersities via the reversible addition-fragmentation chain transfer (RAFT) process using a highly electron deficient RAFT agent that can react with surface-anchored dienes such as cyclopentadiene. We demonstrate that the anchoring method is facile to perform and highly suitable for preparing patterned surfaces that are passivated against biological impact in well-defined areas.

  12. Solid state interaction of raloxifene HCl with different hydrophilic carriers during co-grinding and its effect on dissolution rate.

    Science.gov (United States)

    Garg, Anuj; Singh, S; Rao, V U; Bindu, K; Balasubramaniam, J

    2009-04-01

    This study investigated the effects of different classes of hydrophilic carriers (poly vinyl pyrrolidones [PVPs] [Plasdone K-25 and Plasdone S-630], cellulosic polymers [hydroxypropyl methyl cellulose and hydroxy propyl cellulose], and Sodium Alginate) on the solid state and dissolution rate of Raloxifene hydrochloride (R-HCl). Solid state characterizations of co-ground mixtures and physical mixtures in 1:1 and 1:2 ratios of drug to polymer were performed by employing laser diffractometer for particle size and differential scanning calorimetry (DSC) for solid state interactions. The results of particle size studies showed that only co-grinding with PVPs was more effective in the reduction of particle size than the milling of drug alone. DSC study indicated that the crystalline nature of the drug was reduced after co-grinding with PVPs when compared with their corresponding physical mixtures. The hydrophilic carriers other than PVPs did not reduce the crystalline nature of the drug significantly. X-ray diffraction and scanning electron microscopy were carried out for selected batches to confirm DSC results. Significant enhancement in dissolution rate and extent was observed with co-ground mixtures of drug and PVPs. Plasdone S-630 was found to be a better carrier for R-HCl in terms of achieving improvement in dissolution. In vitro dissolution data can be described by Hixson-Crowell model, indicating the drug release mechanism predominated by erosion.

  13. 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.

  14. RGD surface functionalization of the hydrophilic acrylic intraocular lens material to control posterior capsular opacification.

    Directory of Open Access Journals (Sweden)

    Yi-Shiang Huang

    Full Text Available Posterior Capsular Opacification (PCO is the capsule fibrosis developed on implanted IntraOcular Lens (IOL by the de-differentiation of Lens Epithelial Cells (LECs undergoing Epithelial Mesenchymal Transition (EMT. Literature has shown that the incidence of PCO is multifactorial including the patient's age or disease, surgical technique, and IOL design and material. Reports comparing hydrophilic and hydrophobic acrylic IOLs have shown that the former has more severe PCO. On the other hand, we have previously demonstrated that the adhesion of LECs is favored on hydrophobic compared to hydrophilic materials. By combining these two facts and contemporary knowledge in PCO development via the EMT pathway, we propose a biomimetically inspired strategy to promote LEC adhesion without de-differentiation to reduce the risk of PCO development. By surface grafting of a cell adhesion molecule (RGD peptide onto the conventional hydrophilic acrylic IOL material, the surface-functionalized IOL can be used to reconstitute a capsule-LEC-IOL sandwich structure, which has been considered to prevent PCO formation in literature. Our results show that the innovative biomaterial improves LEC adhesion, while also exhibiting similar optical (light transmittance, optical bench and mechanical (haptic compression force, IOL injection force properties compared to the starting material. In addition, compared to the hydrophobic IOL material, our bioactive biomaterial exhibits similar abilities in LEC adhesion, morphology maintenance, and EMT biomarker expression, which is the crucial pathway to induce PCO. The in vitro assays suggest that this biomaterial has the potential to reduce the risk factor of PCO development.

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

    Science.gov (United States)

    Rotenberg, Benjamin; Patel, Amish J.; 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 on top of a strongly adsorbed monolayer of water. Our results imply that the interior of hydrophobic zeolites suspended in water may contain adsorbed water molecules at pressures much smaller than the intrusion pressure. PMID:22035164

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

    Science.gov (United States)

    Rotenberg, Benjamin; Patel, Amish J; Chandler, David

    2011-12-21

    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 investigated the influence of the microscopic structure of the surface and the strength of adhesive (surface-water) interactions on surface hydrophobicity. We have shown 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 the 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 on top of a strongly adsorbed monolayer of water. Our results imply that the interior of hydrophobic zeolites suspended in water may contain adsorbed water molecules at pressures much lower than the intrusion pressure. © 2011 American Chemical Society

  17. Exploring the Leishmania Hydrophilic Acylated Surface Protein B (HASPB) Export Pathway by Live Cell Imaging Methods.

    Science.gov (United States)

    MacLean, Lorna; Price, Helen; O'Toole, Peter

    2016-01-01

    Leishmania major is a human-infective protozoan parasite transmitted by the bite of the female phlebotomine sand fly. The L. major hydrophilic acylated surface protein B (HASPB) is only expressed in infective parasite stages suggesting a role in parasite virulence. HASPB is a "nonclassically" secreted protein that lacks a conventional signal peptide, reaching the cell surface by an alternative route to the classical ER-Golgi pathway. Instead HASPB trafficking to and exposure on the parasite plasma membrane requires dual N-terminal acylation. Here, we use live cell imaging methods to further explore this pathway allowing visualization of key events in real time at the individual cell level. These methods include live cell imaging using fluorescent reporters to determine the subcellular localization of wild type and acylation site mutation HASPB18-GFP fusion proteins, fluorescence recovery after photobleaching (FRAP) to analyze the dynamics of HASPB in live cells, and live antibody staining to detect surface exposure of HASPB by confocal microscopy.

  18. The adsorption of trypsin on hydrophilic and hydrophobic surfaces. In situ structural characterization of the enzyme in the adsorbed state

    NARCIS (Netherlands)

    Koutsopoulos, S.; Patzsch, K.; Bosker, W.T.E.; Norde, W.

    2007-01-01

    The adsorption of trypsin onto polystyrene and silica surfaces was investigated by reflectometry, spectroscopic methods, and atomic force microscopy (AFM). The affinity of trypsin for the hydrophobic polystyrene surface was higher than that for the hydrophilic silica surface, but steady-state

  19. 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.

  20. 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.

  1. Hydrophilic crosslinked-polymeric surface capable of effective suppression of protein adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Kamon, Yuri; Inoue, Naoko; Mihara, Erika; Kitayama, Yukiya; Ooya, Tooru; Takeuchi, Toshifumi, E-mail: takeuchi@gold.kobe-u.ac.jp

    2016-08-15

    Highlights: • Three hydrophilic crosslinked polymers were examined for protein adsorption. • All polymers showed low nonspecific adsorption of negatively charged proteins. • Poly(MMPC) showed the lowest adsorption for positively charged proteins. • Poly(MMPC) is able to reduce nonspecific adsorption of a wide range of proteins. - Abstract: We investigated the nonspecific adsorption of proteins towards three hydrophilic crosslinked-polymeric thin layers prepared by surface-initiated atom transfer radical polymerization using N,N′-methylenebisacrylamide, 2-(methacryloyloxy)ethyl-[N-(2-methacryloyloxy)ethyl]phosphorylcholine (MMPC), or 6,6′-diacryloyl-trehalose crosslinkers. Protein binding experiments were performed by surface plasmon resonance with six proteins of different pI values including α-lactalbumin, bovine serum albumin (BSA), myoglobin, ribonuclease A, cytochrome C, and lysozyme in buffer solution at pH 7.4. All of the obtained crosslinked-polymeric thin layers showed low nonspecific adsorption of negatively charged proteins at pH 7.4 such as α-lactalbumin, BSA, and myoglobin. Nonspecific adsorption of positively charged proteins including ribonuclease A, cytochrome C, and lysozyme was the lowest for poly(MMPC). These results suggest poly(MMPC) can effectively reduce nonspecific adsorption of a wide range of proteins that are negatively or positively charged at pH 7.4. MMPC is a promising crosslinker for a wide range of polymeric materials requiring low nonspecific protein binding.

  2. 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.

  3. Hydrophilic surface modification of polymer vascular prostheses and metal endoluminal stents

    Science.gov (United States)

    Amery, Drew Powell

    1997-12-01

    Large diameter vascular replacements of GORE-TEXsp°ler or Dacronsp°ler are frequently used to replace damaged arteries. Poor long term patency of small diameter grafts, 6 millimeters or less, is attributed to platelet adhesion and the inability to regenerate a blood contacting surface of vascular endothelium. Metal endoluminal stents are vascular prostheses used to keep arterial lumens open following angioplasty. Complications for these implants include short term thrombogenicity and long term restenosis. This study was directed to the synthesis and characterization of more biocompatible surfaces for these devices. Gamma radiation induced-graft polymerization and radio frequency plasma activation was investigated to surface modify polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), expanded polytetrafluoroethylene (ePTFE), and 316 stainless steel. To mimic natural biocompatible tissue surfacesl a series of hydrophilic polymers were grafted onto PMMA, PET, and ePTFE. Hydrophilic graft polymers were derived from N-vinyl pyrrolidone (NVP), potassium sulfopropylacrylate (KSPA), and dimethylacrylamide, and were grafted copolymerized with several bioactive compounds in a two step modification process. Complex graft surfaces containing fibronectin (Fn), laminin (Lm), type IV collagen (IV), heparin sulfate (Hp), albumin (Alb), and a synthetic fibronectin like protein polymer (RGD) were prepared. For surface modification of endoluminal stents of 316 stainless and tantalum, a combination of RF plasma activation combined with gamma radiation induced grafting was studied. Plasma deposition of hydrophobic poly(hexane) primer layers with water plasma oxidation were examined for initial metal surface activation. Surfaces were characterized by gravimetric analysis, contact angle goniometry, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Auger depth proGling, optical microscopy (OM), and low voltage scanning electron

  4. Objective assessment of the inflammatory reaction in foldable heparin surface-modified hydrophilic acrylic intraocular lens

    Directory of Open Access Journals (Sweden)

    Tao Liu1

    2016-01-01

    Full Text Available AIM: To investigate the inflammatory reaction in the anterior chamber after cataract surgery for the heparin surface modified foldable hydrophilic acrylic intraocular lens(HSM-IOLby laser flare-cell meter. METHODS: The test group consisted of 22 patients(22 eyesin whom a HSM-IOL was implanted in the capsular bag(HSM-IOL group. There was one control group including 21 patients(21 eyeswho received a normal foldable hydrophilic acrylic IOL(uncoated IOL group. Anterior chamber flare and cell values were measured, using laser flare-cell meter preoperatively and 1, 7, 28d postoperatively. RESULTS: In the HSM-IOL group, the flare and the cells values were significantly lower than those in the uncoated IOL group 1d and 7d postoperatively. Between the two groups, there were no significant differences in cells and the level of flare on the 28d postoperative. CONCLUSION: HSM-IOL can decrease inflammation in early postoperative stage, compared with the uncoated IOL. The laser flare-cell meter provides a safe and objective technique for measuring inflammation in anterior chamber.

  5. 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.

  6. Long-Range Hydrophilic Attraction between Water and Polyelectrolyte Surfaces in Oil.

    Science.gov (United States)

    Shi, Chen; Yan, Bin; Xie, Lei; Zhang, Ling; Wang, Jingyi; Takahara, Atsushi; Zeng, Hongbo

    2016-11-21

    The outstanding water wettability and the capability of polyelectrolyte surfaces to spontaneously clean oil fouling are determined by their wetting mechanism in the surrounding medium. Here, we have quantified the nanomechanics between three types of polyelectrolyte surfaces (i.e. zwitterionic, cationic, and anionic) and water or oil drops using an atomic force microscope (AFM) drop probe technique, and elucidated the intrinsic wetting mechanisms of the polyelectrolyte surfaces in oil and water media. The measured forces between oil drops and polyelectrolyte surfaces in water can be described by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Surprisingly, strong long-range attraction was discovered between polyelectrolyte surfaces and water drops in oil, and the strongest interaction was measured for the polyzwitterion. This unexpected long-range "hydrophilic" attraction in oil could be attributed to a strong dipolar interaction because of the large dipole moment of the polyelectrolytes. Our results provide new nanomechanical insights into the development of novel polyelectrolyte-based materials and coatings for a wide range of engineering, bioengineering, and environmental applications. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Bilayer self-assembly on a hydrophilic, deterministically nano-patterned surface

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Gregory Scott [ORNL; Jung, Seung-Yong [ORNL; Browning, Jim [ORNL; Keum, Jong Kahk [ORNL; Lavrik, Nickolay V [ORNL; Alemseghed, Mussie G [ORNL; Collier, Pat [ORNL

    2013-01-01

    We present measurements of the in-situ, microscopic architecture of a self-assembled bilayer at the interface between a regularly nano-patterned surface and an aqueous sub-phase using neutron reflectometry. The substrate is patterned with a rectangular array of nano-scaled holes. Because of the high quality of the pattern, using neutron reflectometry, we are able to map the surface-normal density distribution of the patterned silicon, the penetration of water into the pattern, and the distribution of a deposited film inside and outside of the etched holes. In this study, 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) single bilayers were deposited on the hydrophilic patterned surface. For bilayers deposited either by vesicle fusion (VF) or by the Langmuir Schaefer (L-S) technique, the most consistent model found to fit the data shows that the lipids form bilayer coatings on top of the substrate as well as the bottoms of the holes in an essentially conformal fashion. However, while there is a single bilayer on the unetched silicon surface, the lipids coating the bottoms of the holes form a complex bimodal structure consistent with a rough surface produced by the etching process. This study provides insight into film transfer both outside and inside regular nano-patterned features.

  8. 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.

  9. The Surface Chemical Properties of Novel High Surface Area Solids ...

    African Journals Online (AJOL)

    Spectroscopic and potentiometric investigations into the surface properties of both solids ... solids (unmodified ash, base-modified ash, acid-etched zeolitic product) are reported. Metal sorption studies were performed for cadmium and copper.

  10. Hydrophilic surface modification of poly(methyl methacrylate)-based ocular prostheses using poly(ethylene glycol) grafting.

    Science.gov (United States)

    Ko, JaeSang; Cho, Kanghee; Han, Sang Won; Sung, Hyung Kyung; Baek, Seung Woon; Koh, Won-Gun; Yoon, Jin Sook

    2017-10-01

    Ocular prostheses are custom-made polymeric inserts that can be placed in anophthalmic sockets for cosmetic rehabilitation. Prosthetic eye wearers have reduced tear amount, and they often experience dry eye symptoms including dryness, irritation, discomfort, and discharge. Most modern ocular prostheses are made of poly(methyl methacrylate) (PMMA), which is highly hydrophobic. Previous research has shown that improving the wettability of contact lens materials decreases its wearers discomfort by increasing lubrication. Therefore, hydrophilic modification of PMMA-based ocular prostheses might also improve patient discomfort by improving lubrication. We modified the surfaces of PMMA-based ocular prostheses using poly(ethylene glycol) (PEG), which is hydrophilic. To do this, we used two strategies. One was a "grafting from" method, whereby PEG was polymerized from the PMMA surface. The other was a "grafting to" method, which involved PEG being covalently bonded to an amine-functionalized PMMA surface. Assessments involving the water contact angle, ellipsometry, and X-ray photoelectron spectroscopy indicated that PEG was successfully introduced to the PMMA surfaces using both strategies. Scanning electron microscopy and atomic force microscopy images revealed that neither strategy caused clinically significant alterations in the PMMA surface morphology. In vitro bacterial adhesion assessments showed that the hydrophilic modifications effectively reduced bacterial adhesion without inducing cytotoxicity. These results imply that hydrophilic surface modifications of conventional ocular prostheses may decrease patient discomfort and ocular prosthesis-related infections. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Friction and Wear Modifiers Using Solvent Partitioning of Hydrophilic Surface-Interactive Chemicals Contained in Boundary Layer-Targeted Emulsions

    Science.gov (United States)

    Richmond, Robert Chaffee (Inventor); Schramm, Jr., Harry F. (Inventor); Defalco, Francis G. (Inventor)

    2017-01-01

    A wear and/or friction reducing additive for a lubricating fluid in which the additive is a combination of a moderately hydrophilic single-phase compound and an anti-wear and/or anti-friction aqueous salt solution. The aqueous salt solution produces a coating on boundary layer surfaces. The lubricating fluid can be an emulsion-free hydrophobic oil, hydraulic fluid, antifreeze, water, or a water-based lubricant. Preferably, the moderately hydrophilic single-phase compound is sulfonated castor oil and the aqueous salt solution additionally contains boric acid and zinc oxide. The emulsions produced by the aqueous salt solutions, the moderately hydrophilic single-phase compounds, or the combination thereof provide targeted boundary layer organizers that significantly enhance the anti-wear and/or anti-friction properties of the base lubricant by decreasing wear and/or friction of sliding and/or rolling surfaces at boundary layers.

  12. From Liposomes to Supported, Planar Bilayer Structures on Hydrophilic and Hydrophobic Surfaces: An Atomic Force Microscopy Study

    OpenAIRE

    Jass, Jana; Tjärnhage, Torbjörn; Puu, Gertrud

    2000-01-01

    The sequence of events involved in the transition from attached liposomes to bilayer patches on hydrophilic and hydrophobic solid supports were visualized in situ by Tapping Mode atomic force microscopy in liquid. In a smooth manner, the attached liposomes spread and flattened from the outer edges toward the center until the two membrane bilayers were stacked on top of each other. The top bilayer then either rolls or slides over the bottom bilayer, and the adjacent edges join to form a larger...

  13. 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.

  14. 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.

  15. 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.; Keizer, de A.; Cohen Stuart, M.A.; 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

  16. 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

  17. Development and characterization of solid dispersion of piroxicam for improvement of dissolution rate using hydrophilic carriers

    Directory of Open Access Journals (Sweden)

    Mohammad Barzegar-jalali

    2014-09-01

    Full Text Available Introduction: The main objective of this study was preparation and characterization of solid dispersion of piroxicam to enhance its dissolution rate. Methods: Solid dispersion formulations with different carriers including crospovidone, microcrystalline cellulose and Elaeagnus angustifolia fruit powder and with different drug: carrier ratios were prepared employing cogrinding method. Dissolution study of the piroxicam powders, physical mixtures and solid dispersions was performed in simulated gastric fluid and simulated intestinal fluid using USP Apparatus type II. The physical characterization of formulations were analyzed using powder X ray diffraction (PXRD, particle size analyzer and differential scanning calorimetry (DSC. Interactions between the drug and carriers were evaluated by Fourier transform infrared (FT-IR spectroscopic method. Results: It was revealed that all of three carriers increase the dissolution rate of piroxicam from physical mixtures and especially in solid dispersions compared to piroxicam pure and treated powders. PXRD and DSC results were confirmed the reduction of crystalline form of piroxicam. FT-IR analysis did not show any physicochemical interaction between drug and carriers in the solid dispersion formulations. Conclusion: Dissolution rate was dependent on the type and ratio of drug: carrier as well as pH of dissolution medium. Dissolution data of formulations were fitted well in to the linear Weibull as well as non-linear logistic and a suggested models.

  18. Surface Modification of Biodegradable Poly(D,L-lactic acid) by Nitrogen and Nitrogen/Hydrogen Plasma for Improving Surface Hydrophilicity

    Science.gov (United States)

    Zhao, Guowei; Gao, Junping; Gao, Qiang; Chen, Yashao

    2011-04-01

    Enhancement of the surface hydrophilicity of biodegradable poly (D,L-lactic acid) (PLA) films is studied. The PLA films were treated by nitrogen plasma (PLA-N2) and nitrogen/hydrogen plasma (PLA-N2/H2), respectively. The surface properties and microstructure of PLA-N2 and PLA-N2/H2 were studied by static contact angle measurement, surface free energy calculation, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). It is confirmed that the surface hydrophilicity of PLA-N2 and PLA-N2/H2 was higher than that of pristine PLA, and the surface hydrophilicity of PLA-N2 films was better than that of PLA-N2/H2.

  19. Gas Bubbles Stabilized by Janus Particles with Varying Hydrophilic-Hydrophobic Surface Characteristics.

    Science.gov (United States)

    Fujii, Syuji; Yokoyama, Yuichi; Nakayama, Saori; Ito, Masanori; Yusa, Shin-Ichi; Nakamura, Yoshinobu

    2018-01-23

    Micrometer-sized polymer-grafted gold-silica (Au-SiO2) Janus particles were fabricated by vacuum evaporation followed by polymer grafting. The Janus particle diameter, diameter distribution, morphology, surface chemistry, and water wettability were characterized by optical microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, and contact angle measurements. The optical microscopy results showed that the polystyrene (PS)-grafted Au-SiO2 Janus particles exhibited monolayer adsorption at the air-water interface and could stabilize bubbles, preventing their coalescence for more than 1 month. The hydrophobic PS-grafted Au and hydrophilic SiO2 surfaces were exposed to the air and water phases, respectively. Bare Au-SiO2 and poly(2-(perfluorobutyl)ethyl methacrylate) (PPFBEM)-grafted Au-SiO2 Janus particles could also stabilize bubbles for up to 2 weeks. By contrast, bare silica particles did not stabilize bubbles and were dispersed in water. The bubbles that formed in the PS-grafted Janus particle system were more stable than those formed in the bare Au-SiO2 Janus particles, PPFBEM-grafted Au-SiO2 Janus particles, and SiO2 particle systems because of the high adsorption energy of the PS-grafted particles at the air-water interface.

  20. Hydrophilic surface coatings with embedded biocidal silver nanoparticles and sodium heparin for central venous catheters.

    Science.gov (United States)

    Stevens, Kris N J; Croes, Sander; Boersma, Rinske S; Stobberingh, Ellen E; van der Marel, Cees; van der Veen, Frederik H; Knetsch, Menno L W; Koole, Leo H

    2011-02-01

    Central venous catheters (CVCs) have become indispensable in the treatment of neonates and patients undergoing chemotherapy or hemodialysis. A CVC provides easy access to the patient's circulation, thus enabling facile monitoring of hemodynamic parameters, nutritional support, or administration of (cytostatic) medication. However, complications with CVCs, such as bacterial bloodstream infection or thromboembolism, are common. Bloodstream infections, predominantly caused by Staphylococcus aureus, are notoriously difficult to prevent and treat. Furthermore, patients receiving infusion therapy through a CVC are at risk for deep-vein thrombosis, especially of the upper limbs. Several recent clinical trials have shown that prophylactic anticoagulation (low-molecular-weight heparin or vitamin K antagonists) is not effective. Here, we report on the systematic development of a new bifunctional coating concept that can -uniquely- be applied to make CVC surfaces antimicrobial and antithrombogenic at the same time. The novel coating consists of a moderately hydrophilic synthetic copolymer of N-vinylpyrrollidinone (NVP) and n-butyl methacrylate (BMA), containing embedded silver nanoparticles (AgNPs) and sodium heparin. The work demonstrates that the AgNPs strongly inhibit adhesion of S. aureus (reference strain and clinical isolates). Surprisingly, heparin not only rendered our surfaces practically non-thrombogenic, but also contributed synergistically to their biocidal activity. Copyright © 2010 Elsevier Ltd. All rights reserved.

  1. 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.

  2. 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. CO{sub 2} laser cleaning of hydrophilic oxidized silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Boughaba, S.; Sacher, E.; Meunier, M. [Ecole Polytechnique, Montreal, Quebec (Canada). Dept. de Genie Physique

    1996-12-31

    Efficient sub-half-micron particle contaminant removal is currently one of the most challenging tasks the microelectronics industry has to meet. The removal of particles as small as 0.1 {micro}m was achieved using a pulsed CO{sub 2} laser to induce the explosive vaporization of condensed water. The surfaces used were hydrophilic oxidized silicon. The contaminant particles were 0.1 {micro}m alumina, 0.1--0.2 {micro}m fumed silica, and 0.1 {micro}m polystyrene latex; their zeta potentials in water vary from positive to negative. The effect of the laser beam energy flux on the cleaning efficiency was thoroughly investigated. The effect of the laser beam energy flux on the cleaning efficiency was thoroughly investigated. It was varied between 0.5 and 3 J/cm{sup 2}. Whatever the nature of the contaminants, the cleaning process was characterized by an upper limit, the surface damage threshold energy density, determined to be 1.5 J/cm{sup 2}. If the removal efficiency drops for the lowest beam energy flux, i.e., 0.5 J/cm{sup 2}, and 0.1 {micro}m Al{sub 2}O{sub 3} particles, no single, sharp removal threshold was observed. Another parameter of importance investigated was the thickness of the condensed water. It was varied by changing the time of exposure of the substrate surface to water vapor before laser irradiation, the vapor flow being fixed to 4,700 ml/min. Exposure times ranging from 1.5 to 2.5 s were evaluated to be the most effective.

  4. On the stability of the polymer brushes formed by adsorption of ionomer complexes on hydrophilic and hydrophobic surfaces.

    Science.gov (United States)

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

    2011-01-15

    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 poly(N-methyl 2-vinyl pyridinium iodide), and a neutral block (poly(vinyl alcohol)) or neutral grafts (poly(ethylene oxide)). The strength of the attachment of the micellar layers to various substrates was evaluated with Atomic Force Microscopy. Flow cell experiments allowed for the evaluation of long-term stability of coatings in lateral flow. Fixed angle optical reflectometry was used to quantify protein (BSA) adsorption on the micellar layers after their exposure to flow. The results show that adsorbed micellar layers are relatively weakly attached to hydrophobic surfaces and much stronger to hydrophilic surfaces, which has a significant impact on their stability. Adsorbed layers maintain their ability to suppress protein adsorption on hydrophilic surfaces but not on hydrophobic surfaces. Due to the relatively weak attachment to hydrophobic surfaces the structure of adsorbed layers may easily be disrupted by lateral forces, such that the complex coacervate-brush structure no longer exists. Copyright © 2010 Elsevier Inc. All rights reserved.

  5. 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.

  6. 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

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

    Energy Technology Data Exchange (ETDEWEB)

    Vatanpour, Vahid, E-mail: vahidvatanpour@khu.ac.ir; Zoqi, Naser

    2017-02-28

    Highlights: • A commercial PA RO membrane was modified by grafting of hydrophilic acrylic acid. • COOH-MWCNTs were mixed in grafting layer to increase permeability and antifouling. • However, more increase of CNTs caused in reduction of flux of the membranes. • Effect of acrylic acid amount, contact time and curing time was optimized. - Abstract: 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

  8. 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). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. New insight into icing and de-icing properties of hydrophobic and hydrophilic structured surfaces based on core-shell particles.

    Science.gov (United States)

    Chanda, Jagannath; Ionov, Leonid; Kirillova, Alina; Synytska, Alla

    2015-12-21

    Icing is an important problem, which often leads to emergency situations in northern countries. The reduction of icing requires a detailed understanding of this process. In this work, we report on a systematic investigation of the effects of geometry and chemical properties of surfaces on the formation of an ice layer, its properties, and thawing. We compare in detail icing and ice thawing on flat and rough hydrophilic and hydrophobic surfaces. We also show advantages and disadvantages of the surfaces of each kind. We demonstrate that water condenses in a liquid form, leading to the formation of a thin continuous water layer on a hydrophilic surface. Meanwhile, separated rounded water droplets are formed on hydrophobic surfaces. As a result of slower heat exchange, the freezing of rounded water droplets on a hydrophobic surface occurs later than the freezing of the continuous water layer on a hydrophilic one. Moreover, growth of ice on hydrophobic surfaces is slower than on the hydrophilic ones, because ice grows due to the condensation of water vapor on already formed ice crystals, and not due to the condensation on the polymer surface. Rough hydrophobic surfaces also demonstrate a very low ice adhesion value, which is because of the reduced contact area with ice. The main disadvantage of hydrophobic and superhydrophobic surfaces is the pinning of water droplets on them after thawing. Flat hydrophilic poly(ethylene glycol)-modified surfaces also exhibit very low ice adhesion, which is due to the very low freezing point of the water-poly(ethylene glycol) mixtures. Water easily leaves from flat hydrophilic poly(ethylene glycol)-modified surfaces, and they quickly become dry. However, the ice growth rate on poly(ethylene glycol)-modified hydrophilic surfaces is the highest. These results indicate that neither purely (super)hydrophobic polymeric surfaces, nor "antifreeze" hydrophilic ones provide an ideal solution to the problem of icing.

  10. 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

  11. Surface Deposition and Phase Behavior of Oppositely Charged Polyion–Surfactant Ion Complexes. Delivery of Silicone Oil Emulsions to Hydrophobic and Hydrophilic Surfaces

    Science.gov (United States)

    2011-01-01

    The adsorption from mixed polyelectrolyte–surfactant solutions at hydrophobized silica surfaces was investigated by in situ null-ellipsometry, and compared to similar measurements for hydrophilic silica surfaces. Three synthetic cationic copolymers of varying hydrophobicity and one cationic hydroxyethyl cellulose were compared in mixtures with the anionic surfactant sodium dodecylsulfate (SDS) in the absence or presence of a dilute silicone oil emulsion. The adsorption behavior was mapped while stepwise increasing the concentration of SDS to a polyelectrolyte solution of constant concentration. The effect on the deposition of dilution of the bulk solution in contact with the surface was also investigated by gradual replacement of the bulk solution with 1 mM aqueous NaCl. An adsorbed layer remained after complete exchange of the polyelectrolyte/surfactant solution for aqueous NaCl. In most cases, there was a codeposition of silicone oil droplets, if such droplets were present in the formulation before dilution. The overall features of the deposition were similar at hydrophobic and hydrophilic surfaces, but there were also notable differences. SDS molecules adsorbed selectively at the hydrophobized silica surface, but not at the hydrophilic silica, which influenced the coadsorption of the cationic polymers. The largest amount of deposited material after dilution was found for hydrophilic silica and for the least-hydrophobic cationic polymers. For the least-hydrophobic polyions, no significant codeposition of silicone oil was detected at hydrophobized silica after dilution if the initial SDS concentration was high. PMID:21667982

  12. Rapid determination of endogenous cytokinins in plant samples by combination of magnetic solid phase extraction with hydrophilic interaction chromatography-tandem mass spectrometry.

    Science.gov (United States)

    Liu, Zhao; Cai, Bao-Dong; Feng, Yu-Qi

    2012-04-01

    A 2-acrylamido-2-methyl-1-propanesulfonic acid-co-ethylene glycol dimethacrylate (Fe₃O₄/SiO₂/P(AMPS-co-EGDMA)) copolymer was prepared and used as a magnetic solid phase extraction (MSPE) medium for recovery of endogenous cytokinins (CKs) from plant extracts. This magnetic porous polymer was characterized by electron microscopy, nitrogen sorption experiments, elemental analysis and Fourier-transformed infrared spectroscopy. It was demonstrated to have high extraction capacity toward CKs in plants due to its specificity, surface area and porous structure. Coupled with hydrophilic interaction chromatography-tandem mass spectrometry (HILIC-MS/MS), a rapid, simple, and effective MSPE-HILIC-MS/MS analytical method for the quantitative analysis of endogenous CKs in Oryza sativa (O. sativa) roots was successfully established. Good linearities were obtained for all CKs investigated with correlation coefficients (R²>0.9975. The results showed that LODs (S/N=3) were ranged from 0.18 to 3.65 pg mL⁻¹. Reproducibility of the method was obtained with intra-day and inter-day relative standard deviations (RSDs) less than 16.1% and the recoveries in plant samples ranged from 72.8% to 115.5%. Finally, the MSPE-HILIC-MS/MS method was applied to several plant samples, and the amounts of endogenous CKs in O. sativa roots, leaves and Arabidopsis thaliana (A. thaliana) were successfully determined. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. 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.

  14. Surface Hydrophilicity of Poly(l-Lactide Acid Polymer Film Changes the Human Adult Adipose Stem Cell Architecture

    Directory of Open Access Journals (Sweden)

    Chiara Argentati

    2018-02-01

    Full Text Available Current knowledge indicates that the molecular cross-talk between stem cells and biomaterials guides the stem cells’ fate within a tissue engineering system. In this work, we have explored the effects of the interaction between the poly(l-lactide acid (PLLA polymer film and human adult adipose stem cells (hASCs, focusing on the events correlating the materials’ surface characteristics and the cells’ plasma membrane. hASCs were seeded on films of pristine PLLA polymer and on a PLLA surface modified by the radiofrequency plasma method under oxygen flow (PLLA+O2. Comparative experiments were performed using human bone-marrow mesenchymal stem cells (hBM-MSCs and human umbilical matrix stem cells (hUCMSCs. After treatment with oxygen-plasma, the surface of PLLA films became hydrophilic, whereas the bulk properties were not affected. hASCs cultured on pristine PLLA polymer films acquired a spheroid conformation. On the contrary, hASCs seeded on PLLA+O2 film surface maintained the fibroblast-like morphology typically observed on tissue culture polystyrene. This suggests that the surface hydrophilicity is involved in the acquisition of the spheroid conformation. Noteworthy, the oxygen treatment had no effects on hBM-MSC and hUCMSC cultures and both stem cells maintained the same shape observed on PLLA films. This different behavior suggests that the biomaterial-interaction is stem cell specific.

  15. Efficiency of blocking of non-specific interaction of different proteins by BSA adsorbed on hydrophobic and hydrophilic surfaces.

    Science.gov (United States)

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

    2010-01-01

    The efficiency of a pre-absorbed bovine serum albumin (BSA) layer in blocking the non-specific adsorption of different proteins on hydrophobic and hydrophilic surfaces was evaluated qualitatively and quantitatively using infrared reflection spectroscopy supported by spectral simulations. A BSA layer with a surface coverage of 35% of a close-packed monolayer exhibited a blocking efficiency of 90-100% on a hydrophobic and 68-100% on a hydrophilic surface, with respect to the non-specific adsorption of concanavalin A (Con A), immunoglobulin G (IgG), and staphylococcal protein A (SpA). This BSA layer was produced using a solution concentration of 1 mg/mL and 30 min incubation time. BSA layers that were adsorbed at conditions commonly employed for blocking (a 12 h incubation time and a solution concentration of 10 mg/mL) exhibited a blocking activity that involved competitive adsorption-desorption. This activity resulted from the formation of BSA-phosphate surface complexes, which correlated with the conformation of adsorbed BSA molecules that was favourable for blocking. The importance of optimisation of the adsorbed BSA layer for different surfaces and proteins to achieve efficient blocking was addressed in this study.

  16. Determination of conjugation rates on solid surfaces

    OpenAIRE

    del Campo I.; Ruiz R; Cuevas A.; Revilla C.; Vielva L.; de la Cruz F.

    2012-01-01

    A cytometric method for the estimation of end-point conjugation rates is developed and adapted to surface conjugation. This method improves the through-put of conjugation assays based on replica-plating and results in less noisy experimental data. Although conjugation on solid surfaces deviates from ideal conditions in which cells are continuously mixed, results show that, within the limits of high initial population densities and short mating times, end-point estimates of the conjugation rat...

  17. 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

  18. 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

  19. Immobilization of heparin on the surface of polypropylene non-woven fabric for improvement of the hydrophilicity and blood compatibility.

    Science.gov (United States)

    Li, Rong; Wang, Hengdong; Wang, Wenfeng; Ye, Yin

    2013-01-01

    A polypropylene non-woven fabric (PPNWF) was exposed to oxygen plasma to produce peroxides on its surface. These peroxides were used to initiate graft polymerization of acrylic acid (AA) on the surface of PPNWF. Direct heparinization was accomplished via a reaction between heparin and PP-PAA (AA grafted PPNWF) which was activated by EDC (N-ethyl-N'-[3-(dimethylamino)propyl] carbodiimide). Indirect heparinized PPNWF was prepared by grafting poly(ethylene oxide) (PEO) on a PP-PAA surface to form PP-PAA-PEO, followed by reaction with heparin which was activated by EDC before use. The surface modified PPNWFs were characterized by attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopy, electron spectroscopy for chemical analysis (ESCA) and contact angle goniometry. It was found that hydrophilicity was greatly improved, as indicated by the decrease of the water contact angle from 142 to 33°. In vitro blood compatibility evaluation of modified PPNWFs, including hemolysis rate, platelet adhesion, plasma protein adsorption and activated partial thromboplastin time (APTT) was investigated. The results suggested that both heparinized PPNWFs showed lower hemolysis rates and better platelet anti-adhesion than non-heparinized controls. Furthermore, PPNWF obtained via indirect immobilization of heparin showed better hydrophilicity and blood compatibility than direct heparinization of PPNWF.

  20. Adsorption behavior of a human monoclonal antibody at hydrophilic and hydrophobic surfaces.

    Science.gov (United States)

    Couston, Ruairidh G; Skoda, Maximilian W; Uddin, Shahid; van der Walle, Christopher F

    2013-01-01

    One aspiration for the formulation of human monoclonal antibodies (mAb) is to reach high solution concentrations without compromising stability. Protein surface activity leading to instability is well known, but our understanding of mAb adsorption to the solid-liquid interface in relevant pH and surfactant conditions is incomplete. To investigate these conditions, we used total internal reflection fluorescence (TIRF) and neutron reflectometry (NR). The mAb tested ("mAb-1") showed highest surface loading to silica at pH 7.4 (~12 mg/m(2)), with lower surface loading at pH 5.5 (~5.5 mg/m(2), further from its pI of 8.99) and to hydrophobized silica (~2 mg/m(2)). The extent of desorption of mAb-1 from silica or hydrophobized silica was related to the relative affinity of polysorbate 20 or 80 for the same surface. mAb-1 adsorbed to silica on co-injection with polysorbate (above its critical micelle concentration) and also to silica pre-coated with polysorbate. A bilayer model was developed from NR data for mAb-1 at concentrations of 50-5000 mg/L, pH 5.5, and 50-2000 mg/L, pH 7.4. The inner mAb-1 layer was adsorbed to the SiO₂ surface at near saturation with an end-on" orientation, while the outer mAb-1 layer was sparse and molecules had a "side-on" orientation. A non-uniform triple layer was observed at 5000 mg/L, pH 7.4, suggesting mAb-1 adsorbed to the SiO₂ surface as oligomers at this concentration and pH. mAb-1 adsorbed as a sparse monolayer to hydrophobized silica, with a layer thickness increasing with bulk concentration - suggesting a near end-on orientation without observable relaxation-unfolding.

  1. Adsorption behavior of a human monoclonal antibody at hydrophilic and hydrophobic surfaces

    Science.gov (United States)

    Couston, Ruairidh G.; Skoda, Maximilian W.; Uddin, Shahid; van der Walle, Christopher F.

    2013-01-01

    One aspiration for the formulation of human monoclonal antibodies (mAb) is to reach high solution concentrations without compromising stability. Protein surface activity leading to instability is well known, but our understanding of mAb adsorption to the solid-liquid interface in relevant pH and surfactant conditions is incomplete. To investigate these conditions, we used total internal reflection fluorescence (TIRF) and neutron reflectometry (NR). The mAb tested (“mAb-1”) showed highest surface loading to silica at pH 7.4 (~12 mg/m2), with lower surface loading at pH 5.5 (~5.5 mg/m2, further from its pI of 8.99) and to hydrophobized silica (~2 mg/m2). The extent of desorption of mAb-1 from silica or hydrophobized silica was related to the relative affinity of polysorbate 20 or 80 for the same surface. mAb-1 adsorbed to silica on co-injection with polysorbate (above its critical micelle concentration) and also to silica pre-coated with polysorbate. A bilayer model was developed from NR data for mAb-1 at concentrations of 50–5000 mg/L, pH 5.5, and 50–2000 mg/L, pH 7.4. The inner mAb-1 layer was adsorbed to the SiO2 surface at near saturation with an end-on” orientation, while the outer mAb-1 layer was sparse and molecules had a “side-on” orientation. A non-uniform triple layer was observed at 5000 mg/L, pH 7.4, suggesting mAb-1 adsorbed to the SiO2 surface as oligomers at this concentration and pH. mAb-1 adsorbed as a sparse monolayer to hydrophobized silica, with a layer thickness increasing with bulk concentration - suggesting a near end-on orientation without observable relaxation-unfolding. PMID:23196810

  2. Drop Impact on a Solid Surface

    KAUST Repository

    Josserand, C.

    2015-09-22

    © Copyright 2016 by Annual Reviews. All rights reserved. A drop hitting a solid surface can deposit, bounce, or splash. Splashing arises from the breakup of a fine liquid sheet that is ejected radially along the substrate. Bouncing and deposition depend crucially on the wetting properties of the substrate. In this review, we focus on recent experimental and theoretical studies, which aim at unraveling the underlying physics, characterized by the delicate interplay of not only liquid inertia, viscosity, and surface tension, but also the surrounding gas. The gas cushions the initial contact; it is entrapped in a central microbubble on the substrate; and it promotes the so-called corona splash, by lifting the lamella away from the solid. Particular attention is paid to the influence of surface roughness, natural or engineered to enhance repellency, relevant in many applications.

  3. Chirality in adsorption on solid surfaces.

    Science.gov (United States)

    Zaera, Francisco

    2017-12-07

    In the present review we survey the main advances made in recent years on the understanding of chemical chirality at solid surfaces. Chirality is an important topic, made particularly relevant by the homochiral nature of the biochemistry of life on Earth, and many chiral chemical reactions involve solid surfaces. Here we start our discussion with a description of surface chirality and of the different ways that chirality can be bestowed on solid surfaces. We then expand on the studies carried out to date to understand the adsorption of chiral compounds at a molecular level. We summarize the work published on the adsorption of pure enantiomers, of enantiomeric mixtures, and of prochiral molecules on chiral and achiral model surfaces, especially on well-defined metal single crystals but also on other flat substrates such as highly ordered pyrolytic graphite. Several phenomena are identified, including surface reconstruction and chiral imprinting upon adsorption of chiral agents, and the enhancement or suppression of enantioselectivity seen in some cases upon adsorption of enantiomixtures of chiral compounds. The possibility of enhancing the enantiopurity of adsorbed layers upon the addition of chiral seeds and the so-called "sergeants and soldiers" phenomenon are presented. Examples are provided where the chiral behavior has been associated with either thermodynamic or kinetic driving forces. Two main approaches to the creation of enantioselective surface sites are discussed, namely, via the formation of supramolecular chiral ensembles made out of small chiral adsorbates, and by adsorption of more complex chiral molecules capable of providing suitable chiral environments for reactants by themselves, via the formation of individual adsorbate:modifier adducts on the surface. Finally, a discussion is offered on the additional effects generated by the presence of the liquid phase often required in practical applications such as enantioselective crystallization, chiral

  4. Maskless Hydrophilic Patterning of the Superhydrophobic Aluminum Surface by an Atmospheric Pressure Microplasma Jet for Water Adhesion Controlling.

    Science.gov (United States)

    Liu, Jiyu; Song, Jinlong; Wang, Guansong; Chen, Faze; Liu, Shuo; Yang, Xiaolong; Sun, Jing; Zheng, Huanxi; Huang, Liu; Jin, Zhuji; Liu, Xin

    2018-02-19

    Superhydrophobic surfaces with hydrophilic patterns have great application potential in various fields, such as microfluidic systems and water harvesting. However, many reported preparation methods involve complicated devices and/or masks, making fabrication of these patterned surfaces time-consuming and inefficient. Here, we propose a highly efficient, simple, and maskless microplasma jet (MPJ) treatment method to prepare hydrophilic patterns such as dots, lines, and curves on superhydrophobic aluminum substrates. Contact angles, sliding angles, adhesive forces, and droplet impact behavior of the created patterns are investigated and analyzed. The prepared "dot" patterns exhibit great water adhesion, whereas the "line" patterns show anisotropic adhesion. Additionally, the MPJ treatment does not obviously change the surface structures, which makes it possible to achieve repeatable patterning on one substrate. The adhesion behavior of these patterns could be adjusted using MPJs with different diameters. MPJs with larger diameters are efficient for the creation of patterns with high water adhesion, which can be potentially used for open-channel lab-on-chip systems (e.g., continuous water transportation), whereas MPJs with smaller diameters are preferable in preparing patterns with low water adhesion for diverse applications in biomedical fields (e.g., lossless liquid droplet mixing and cell screening).

  5. Simulation of sessile and transient droplets and complex flow dynamics on rough hydrophobic and hydrophilic surfaces using a parallelized Smoothed Particle Hydrodynamics model

    Science.gov (United States)

    Shigorina, Elena; Kordilla, Jannes; Tartakovsky, Alexandre

    2017-04-01

    Flow in unsaturated fractures still remains a challenging aspect of vadose zone research. Fracture may create highly efficient preferential flow paths, which trigger the formation of highly complex and non-linear flow modes, such as droplets, rivulets and films. The understanding of these flow types requires adequate numerical techniques. Here we employ a pairwise-force Smoothed Particle Hydrodynamics (PF-SPH) model to simulate sessile and transient droplets as well as flow mode distributions on rough hydrophobic and hydrophilic surfaces. The wettability of solid surfaces depends on their geometrical structure, i.e., the roughness, as well as the fluid properties. Droplets on rough surfaces may exist in a Cassie, Wenzel or Cassie-Wenzel state. Cassie droplets touch the surface only at few points and stay on the top of the rough surface, Wenzel droplets "fill" the surface roughness, and Cassie-Wenzel droplets partially penetrate small surface depressions and/or partially touch only elevated points of the surface. We employ four types of rough surfaces: (1) with a shape of a sinusoidal function along one direction; (2) with a shape of a sinusoidal function in both horizontal directions; (3) with longitudinal rectangular grooves placed on top of a flat surface and (4) with rectangular bars placed on top of a flat surface. It is demonstrated that the static contact angles of Cassie and Wenzel droplets on rough surfaces is greater than the static contact angle on a smooth surface with the same chemical composition, however, Wenzel droplets exhibit a much stronger dependence on the surface geometry. Furthermore, we study the impact of the roughness orientation (i.e., an anisotropic roughness) and surface inclination on droplet flow velocities. Simulations show that the droplet flow velocities are lower if the surface roughness is oriented perpendicular to the direction of flow. If the predominant elements of surface roughness are in alignment with the flow direction, the

  6. 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.

  7. The effect of adsorbed fibronectin and osteopontin on macrophage adhesion and morphology on hydrophilic and hydrophobic model surfaces.

    Science.gov (United States)

    Maciel, J; Oliveira, M I; Gonçalves, R M; Barbosa, M A

    2012-10-01

    Macrophages play a crucial role in the host response to biomaterials. Here we investigated the effect of adsorbed fibronectin (FN) and osteopontin (OPN), two important proteins for tissue repair, on macrophage adhesion and morphology. Since cell-biomaterial interactions are modulated via proteins adsorbed onto biomaterial surfaces, FN and OPN were adsorbed on model self-assembled monolayers (SAMs) of alkanethiols on gold with different functional terminal groups (CH(3), OH and tetra(ethylene-glycol)). The initial interaction of inflammatory cells with a biomaterial is crucial for the ensuing phases of an inflammatory reaction. For this reason short-term cultures of primary human macrophages were performed. To account for the competitive adsorption of other proteins serum was added to the culture medium and the effect compared with serum-free medium cultures. In the presence of serum hydrophilic surfaces increased macrophage adhesion. In particular, FN induced a higher cell density, while OPN tended to decrease it. In serum-free medium cell adhesion was greater on hydrophobic surfaces, except for OPN-coated SAMs. Importantly, FN no longer enhanced macrophage adhesion, while OPN maintained its inhibitory effect. Cell polarization studies indicated that macrophage morphology variations induced by surface chemistry are overcome by pre-adsorbed OPN. Taken together our results show that in the presence of serum macrophage adhesion is promoted by FN hydrophilic surfaces, but impaired on OPN-coated surfaces. The effects of inhibited macrophage adhesion on macrophage fusion, and its relevance to the initial stages of the inflammatory response to biomaterials are discussed. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  8. Impact of hydrophilic and hydrophobic functionalization of flat TiO2/Ti surfaces on proteins adsorption

    Science.gov (United States)

    Fabre, Héloïse; Mercier, Dimitri; Galtayries, Anouk; Portet, David; Delorme, Nicolas; Bardeau, Jean-François

    2018-02-01

    Controlling adsorption of proteins onto medical devices is a key issue for implant-related infections. As self-assembled monolayers (SAMs) on titanium oxide represent a good model to study the surface-protein interactions, TiO2 surface properties were modified by grafting bisphosphonate molecules terminated with hydrophilic poly(ethylene glycol) groups and hydrophobic perfluoropolyether ones, respectively. Characterisation of the surface chemistry and surface topography of the modified surfaces was performed using XPS and atomic force microscopy (AFM). Quartz-crystal microbalance with dissipation (QCM-D) was used to determine the mass of adsorbed proteins as well as its kinetics. Poly(ethylene glycol)-terminated SAMs were the most effective surfaces to limit the adsorption of both BSA and fibrinogen in comparison to perfluorinated-terminated SAMs and non-modified TiO2 surfaces, as expected. The adsorption was not reversible in the case of BSA, while a partial reversibility was observed with Fg, most probably due to multilayers of proteins. The grafted surfaces adsorbed about the same quantity of proteins in terms of molecules per surface area, most probably in monolayer or island-like groups of adsorbed proteins. The adsorption on pristine TiO2 reveals a more important, non-specific adsorption of proteins.

  9. APPLICATION OF SOLID PHASE MICROEXTRACTION GC/MS TO THE CHARACTERIZATION OF HYDROPHILIC DISINFECTION BY-PRODUCTS IN WATER

    Science.gov (United States)

    The U.S. Environmental Protection Agency has given high priority to research aimed at developing methods to extract hydrophilic disinfection by-products (DBPs) from drinking water. Public water supplies are treated with a variety of chemicals aimed at reducing or eliminating inf...

  10. Adsorption and activity of Thermomyces lanuginosus lipase on hydrophobic and hydrophilic surfaces measured with dual polarization interferometry (DPI) and confocal microscopy.

    Science.gov (United States)

    Sonesson, Andreas W; Callisen, Thomas H; Brismar, Hjalmar; Elofsson, Ulla M

    2008-02-15

    The adsorption and activity of Thermomyces lanuginosus lipase (TLL) was measured with dual polarization interferometry (DPI) and confocal microscopy at a hydrophilic and hydrophobic surface. In the adsorption isotherms, it was evident that TLL both had higher affinity for the hydrophobic surface and adsorbed to a higher adsorbed amount (1.90 mg/m(2)) compared to the hydrophilic surface (1.40-1.50mg/m(2)). The thickness of the adsorbed layer was constant (approximately 3.5 nm) on both surfaces at an adsorbed amount >1.0mg/m(2), but decreased on the hydrophilic surface at lower surface coverage, which might be explained by partially unfolding of the TLL structure. However, a linear dependence of the refractive index of the adsorbed layer on adsorbed amount of TLL on C18 surfaces indicated that the structure of TLL was similar at low and high surface coverage. The activity of adsorbed TLL was measured towards carboxyfluorescein diacetate (CFDA) in solution, which upon lipase activity formed a fluorescent product. The surface fluorescence intensity increase was measured in a confocal microscope as a function of time after lipase adsorption. It was evident that TLL was more active on the hydrophilic surface, which suggested that a larger fraction of adsorbed TLL molecules were oriented with the active site facing the solution compared to the hydrophobic surface. Moreover, most of the activity remained when the TLL surface coverage decreased. Earlier reports on TLL surface mobility on the same surfaces have found that the lateral diffusion was highest on hydrophilic surfaces and at low surface coverage of TLL. Hence, a high lateral mobility might lead to a longer exposure time of the active site towards solution, thereby increasing the activity against a water-soluble substrate.

  11. Meniscus and viscous forces during separation of hydrophilic and hydrophobic smooth/rough surfaces with symmetric and asymmetric contact angles.

    Science.gov (United States)

    Cai, Shaobiao; Bhushan, Bharat

    2008-05-13

    Adhesive or repulsive forces contributed by both meniscus and viscous forces can be significant and become one of the main reliability issues when the contacting surfaces are ultra smooth, and the normal load is small, as is common for micro/nano devices. In this study, both meniscus and viscous forces during separation for smooth and rough hydrophilic and hydrophobic surfaces are studied. The effects of separation distance, initial meniscus height, separation time, contact angle and roughness are presented. Meniscus force decreases with an increase of separation distance, whereas the viscous force has an opposite trend. Both forces decrease with an increase of initial meniscus height. An increase of separation time, initial meniscus height or a decrease of contact angle leads to an increase of critical meniscus area at which both forces are equivalent. An increase in contact angle leads to a decrease of attractive meniscus force but an increase of repulsive meniscus force (attractive or repulsive dependent on hydrophilic or hydrophobic surface, respectively). Contact angle has a limited effect on the viscous force. For asymmetric contact angles, the magnitude of the meniscus force and the critical meniscus area are in between the values for the two angles. An increase in the number of surface asperities (roughness) leads to an increase of meniscus force; however, its effect on viscous force is trivial. A slightly attractive force is observed for the hydrophobic surface during the end stage of separation though the magnitude is small. The study provides a fundamental understanding of the physics of the separation process and it can be useful for control of the forces in nanotechnology applications.

  12. 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.

  13. 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.

  14. 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. PMID:22605965

  15. Atomistic simulations of wetting properties and water films on hydrophilic surfaces

    Science.gov (United States)

    Kanduč, Matej; Netz, Roland R.

    2017-04-01

    We use molecular simulations to investigate the wetting behavior of water at flat polar surfaces. Introducing a computational procedure based on thermodynamic integration methods, we determine the equilibrium water film thickness on the surface at given vapor density as well as the corresponding change of the surface free energy. The wetting film is relevant on polar surfaces near the wetting transition and significantly alters the surface contact angle. For thin films, the surface free energy change increases linearly with the thickness, as predicted by simple thermodynamic arguments. For thick films we observe deviations from linearity, which we rationalize by the formation of hydrogen bonds between water molecules in the film. Our approach provides an efficient and accurate technique to calculate the wetting properties of surface layers, which we verify by simulating water droplets on the surfaces.

  16. Comparison of the fouling release properties of hydrophobic fluorinated and hydrophilic PEGylated block copolymer surfaces: attachment strength of the diatom Navicula and the green alga Ulva.

    Science.gov (United States)

    Krishnan, Sitaraman; Wang, Nick; Ober, Christopher K; Finlay, John A; Callow, Maureen E; Callow, James A; Hexemer, Alexander; Sohn, Karen E; Kramer, Edward J; Fischer, Daniel A

    2006-05-01

    To understand the role of surface wettability in adhesion of cells, the attachment of two different marine algae was studied on hydrophobic and hydrophilic polymer surfaces. Adhesion of cells of the diatom Navicula and sporelings (young plants) of the green macroalga Ulva to an underwater surface is mainly by interactions between the surface and the adhesive exopolymers, which the cells secrete upon settlement and during subsequent colonization and growth. Two types of block copolymers, one with poly(ethylene glycol) side-chains and the other with liquid crystalline, fluorinated side-chains, were used to prepare the hydrophilic and hydrophobic surfaces, respectively. The formation of a liquid crystalline smectic phase in the latter inhibited molecular reorganization at the surface, which is generally an issue when a highly hydrophobic surface is in contact with water. The adhesion strength was assessed by the fraction of settled cells (Navicula) or biomass (Ulva) that detached from the surface in a water flow channel with a wall shear stress of 53 Pa. The two species exhibited opposite adhesion behavior on the same sets of surfaces. While Navicula cells released more easily from hydrophilic surfaces, Ulva sporelings showed higher removal from hydrophobic surfaces. This highlights the importance of differences in cell-surface interactions in determining the strength of adhesion of cells to substrates.

  17. 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.

  18. Understanding protein adsorption phenomena at solid surfaces.

    Science.gov (United States)

    Rabe, Michael; Verdes, Dorinel; Seeger, Stefan

    2011-02-17

    Protein adsorption at solid surfaces plays a key role in many natural processes and has therefore promoted a widespread interest in many research areas. Despite considerable progress in this field there are still widely differing and even contradictive opinions on how to explain the frequently observed phenomena such as structural rearrangements, cooperative adsorption, overshooting adsorption kinetics, or protein aggregation. In this review recent achievements and new perspectives on protein adsorption processes are comprehensively discussed. The main focus is put on commonly postulated mechanistic aspects and their translation into mathematical concepts and model descriptions. Relevant experimental and computational strategies to practically approach the field of protein adsorption mechanisms and their impact on current successes are outlined. Copyright © 2011 Elsevier B.V. All rights reserved.

  19. Fluoroalkylated Silicon-Containing Surfaces - Estimation of Solid Surface Energy

    Science.gov (United States)

    2010-10-20

    NAME OF RESPONSIBLE PERSON Dr. Joseph M. Mabry a. REPORT Unclassified b . ABSTRACT Unclassified c. THIS PAGE Unclassified SAR 33 19b...and the liquid ( cllW = 2γlv), where c ssW c llW =4γsvγlv. The Berthelot geometric mean mixing rule suggests that the work of adhesion can be...were computed from the advancing contact angle data (Figure 4). The calculated values of the solid surface energy monotonically increase from γsv

  20. 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.

  1. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Tingting; Zhang, Jun, E-mail: zhangjun@njtech.edu.cn

    2016-12-01

    Highlights: • Surface hydrophilic modified ABS was prepared by melt blending with PETG. • O= C−O groups were enriched on the surface with increasing PETG content. • Hydrophilic property of the blends was enhanced with increasing PETG content. • Phase inversion behavior of the blends occurred around intermediate composition. • Tensile and flexural strength were enhanced with increasing PETG content. - Abstract: 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

  3. Amphiphilic Surface Active Triblock Copolymers with Mixed Hydrophobic and Hydrophilic Side Chains for Tuned Marine Fouling-Release Properties

    Energy Technology Data Exchange (ETDEWEB)

    Park, D.; Weinman, C; Finlay, J; Fletcher, B; Paik, M; Sundaram, H; Dimitriou, M; Sohn, K; Callow, M; et al.

    2010-01-01

    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{sub n} {approx} 550 g/mol (PEG550)] and a semifluorinated alcohol (CF{sub 3}(CF{sub 2}){sub 9}(CH{sub 2}){sub 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.

  4. 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

    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...

  5. Biologically inspired tunable hydrophilic/hydrophobic surfaces: a copper oxide self-assembly multitier approach.

    Science.gov (United States)

    Zhang, Bong June; Park, Jiyeon; Kim, Kwang J; Yoon, Hyungkee

    2012-09-01

    In this study, a fabrication method for biologically inspired superhydrophobic micro- and nano-structured tier surfaces, each made of a self-assembled copper oxide, is presented. The method is controllable and applicable to bulk production when compared to existing high-end fabrication techniques. By modulating wet chemistry, different shapes and scales of tier structures were created. We demonstrated that their wetting behaviors are closely related to morphological information such as pitch, height and shape. To characterize their wetting behaviors, several experiments were designed and executed. In static water contact angle (WCA) measurements, morphological modulation led to wide WCA range (17°-95°). After hydrophobic self-assembly monolayer of 1-dodecanethiol, their WCA was escalated into superhydrophobic regime. In dynamic WCA, the contact angle hysteresis is greatly reduced by hybridizing the micro- and nano-tier (multiple tiers) when compared to utilizing a single tier. Also, the modification of the surface structure influences the rate of evaporation. In an analytical approach, the multiple tiers show a lower surface free energy compared to that of the single tier. By hybridizing different scales and shapes of tiers-such as hemispheric and conic shapes-the multiple tiers can efficiently reduce the surface energy barrier. Eventually, these manipulations lead to a subtle WCA hysteresis during the liquid motion testing. The analytical results are consistent with the dynamic WCA measurements. The multiple tiers also stabilize the Cassie regime and result in an increased hydrophobicity, which is more than when a single tier is employed.

  6. Visualized study on the interaction between single bubbles and curved solid surface in flotation separation process.

    Science.gov (United States)

    Yang, Liwei; Zhao, Yue; Yang, Jingjing; Li, Yanpeng; Meng, Qinglong

    2014-01-01

    The present study has been devoted to bubble-curved solid surface interaction in water, which is critical to the separation of suspended particles by air flotation. For this purpose, two particular stages of the interaction (collision and attachment) have been examined visually using high-speed photography in a laboratory-scale flotation column. The effects of the surface material and surfactant concentration on these two stages have been also studied quantitatively. The considered solid materials are the cleaned glass as hydrophilic surface and Teflon as hydrophobic surface. The experimental results show that the presence of surfactant significantly affects the collision and rebound process of a gas bubble, while there is no obvious effect of the surface material on the rebound process. An increase in surfactant concentration has been observed to suppress the rebound number and maximal distance of the bubble from the surface. Moreover, the three-phase contact time of the bubble is a strong function of the surfactant concentration and surface hydrophobicity as well as of the bubble diameter. Another important finding is that the bubble attachment is only observed at the hydrophobic Teflon surface below the surfactant CMC (critical micelle concentration). Results of this study are relevant for deep understanding of the attachment mechanism and to determine the proper conditions for a selective flotation process.

  7. 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.

  8. Poly(ethylene glycol)-grafted cyclic acetals based polymer networks with non-water-swellable, biodegradable and surface hydrophilic properties

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Ruixue, E-mail: qdruinyan@hotmail.com [Complex and Intelligent Research Center, School of Mechanical and Power Engineering, East China University of Science and Technology, Shanghai (China); Zhang, Nan; Wu, Wentao [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China); Wang, Kemin, E-mail: kemin-wang@hotmail.com [School of Materials Science and Engineering, Changzhou University, Changzhou 213164 (China)

    2016-05-01

    Cyclic acetals based biomaterial without acidic products during hydrolytic degradation is a promising candidate for tissue engineering applications; however, low hydrophilicity is still one limitation for its biomedical application. In this work, we aim to achieve non-water-swellable cyclic acetal networks with improved hydrophilicity and surface wettability by copolymerization of cyclic acetal units based monomer, 5-ethyl-5-(hydroxymethyl)-β,β-dimethyl-1, 3-dioxane-2-ethanol diacrylate (EHD) and methoxy poly(ethylene glycol) monoacrylate (mPEGA) under UV irradiation, to avoid swelling of conventional hydrogels which could limit their applicability in particular of the mechanical properties and geometry integrity. Various EHD/mPEGA networks were fabricated with different concentrations of mPEGA from 0 to 30%, and the results showed photopolymerization behavior, mechanical property and thermal stability could not be significantly affected by addition of mPEGA, while the surface hydrophilicity was dramatically improved with the increase of mPEGA and could achieve a water contact angle of 37° with 30% mPEGA concentration. The obtained EHD/mPEGA network had comparative degradation rate to the PECA hydrogels reported previously, and MTT assay indicated it was biocompatible to L929 cells. - Highlights: • Cyclic acetals contained EHD/mPEGA networks were fabricated by photopolymerization. • It can be degraded under simulated physiological condition without acidic products. • Surface hydrophilicity was increased without swelling in water.

  9. A Simple Nanocellulose Coating for Self-Cleaning upon Water Action: Molecular Design of Stable Surface Hydrophilicity.

    Science.gov (United States)

    Huang, Shu; Wang, Dayang

    2017-07-24

    Coating solid surfaces with cellulose nanofibril (CNF) monolayers via physical deposition was found to keep the surfaces free of a variety of oils, ranging from viscous engine oil to polar n-butanol, upon water action. The self-cleaning function was well correlated with the unique molecular structure of the CNF, in which abundant surface carboxyl and hydroxy groups are uniformly, densely, and symmetrically arranged to form a polar corona on a crystalline nanocellulose strand. This isotropic core-corona configuration offers new and easily adoptable guidance to design self-cleaning surfaces at the molecular level. Thanks to its excellent self-cleaning behavior, the CNF coating converted conventional meshes into highly effective membranes for oil-water separation with no prior surface treatment required. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Effect of solid waste landfill on underground and surface water ...

    African Journals Online (AJOL)

    The effect of the municipal solid waste landfill a Ring Road Ibadan on the quality of the underground water in the surrounding area and adjacent surface water was investigated. Samples of water from these sources were analyzed for the following physico-chemical parameters: Ph , conductivity, total solid, dissolved solid, ...

  11. Water adsorption on hydrophilic and hydrophobic self-assembled monolayers as proxies for atmospheric surfaces. A grand canonical Monte Carlo simulation study.

    Science.gov (United States)

    Szori, Milán; Jedlovszky, Pál; Roeselová, Martina

    2010-05-14

    Grand canonical Monte Carlo simulations are used to determine water adsorption on prototypical organic surfaces as a function of relative humidity at 300 K. Three model surfaces formed by well-ordered self-assembled monolayers (SAMs) of alkanethiolate chains on gold are investigated: (i) a smooth hydrophobic surface of methyl-terminated C(7)-CH(3) SAM; (ii) a rough hydrophobic surface of randomly mixed two-component SAM, composed of equal fractions of C(5)-CH(3) and C(7)-CH(3) chains (C(5)/C(7)-CH(3) SAM); and (iii) a smooth hydrophilic surface of carboxyl-terminated C(7)-COOH SAM. The all atom CHARMM22 force field is used for the SAM chains together with the SPC/E model for water. No noticeable water adsorption is observed on the smooth hydrophobic surface up to saturation. The mild surface roughness introduced by the uneven chain length of the two components constituting the C(5)/C(7)-CH(3) SAM has no significant effect on the surface hydrophobicity, and the rough hydrophobic surface also remains dry up to the point when water condensation occurs. In contrast, water readily adsorbs onto the hydrophilic surface by forming hydrogen bonds with the COOH groups of the substrate. In addition, hydrogen bonding with pre-adsorbed water molecules contributes to the mechanism of water uptake. Under low humidity conditions, water is present on the hydrophilic surface as individual molecules or small water clusters and, with increasing relative humidity, the surface coverage grows continuously beyond a monolayer formation. The adsorbed water film is observed to be rather inhomogeneous with patches of bare surface exposed. The amount of water constituting a stable adsorption layer prior to condensation is estimated to consist of about 2-5 molecular layers. Detailed analysis of the simulation results is used to obtain important insights into the structure and energetics of water adsorbed on highly oxidized organic surfaces exposed to ambient air of increasing relative humidity.

  12. 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.

  13. Sample preparation for mass spectrometric analysis of human serum N-glycans using hydrophilic interaction chromatography-based solid phase extraction.

    Science.gov (United States)

    Cao, Liwei; Zhang, Ye; Chen, Linlin; Shen, Aijin; Zhang, Xingwang; Ren, Shifang; Gu, Jianxin; Yu, Long; Liang, Xinmiao

    2014-09-21

    Expression levels of N-linked glycans derived from human serum glycoproteins have been shown to change during the progression of many diseases. Generally, N-glycans released from human serum proteins co-exist with endogenous serum peptides, salts, and other contaminants. Effective removal of these contaminants is essential to obtain the glycan profile of human serum proteins. Here, we developed a sample preparation method for mass spectrometry (MS) analysis of N-linked glycans derived from human serum glycoproteins based on a zwitterionic hydrophilic material named Click TE-Cys. The high hydrophilicity of Click TE-Cys, resulting from its unique surface structure and charge distribution, facilitated removal of co-existing salts and endogenous serum peptides. Furthermore, the present enrichment approach was handled in parallel, thus saving time. Using this method, a total of 47 unique N-glycans released from human serum proteins were identified. The intrabatch and interbatch coefficients of variation for the 47 N-linked glycans were 8.57% ± 0.96% and 9.22% ± 1.03%, respectively. These results demonstrate that the present method is suitable for fast purification of N-linked glycans derived from human serum glycoproteins, and has potential for clinical application.

  14. Effect of incorporating graphene oxide and surface imprinting on polysulfone membranes on flux, hydrophilicity and rejection of salt and polycyclic aromatic hydrocarbons from water

    Science.gov (United States)

    Kibechu, Rose Waithiegeni; Ndinteh, Derek Tantoh; Msagati, Titus Alfred Makudali; Mamba, Bhekie Briliance; Sampath, S.

    2017-08-01

    We report a significant enhancement of hydrophillity of polysulfone (Psf) membranes after modification with graphene oxide (GO) as a filler followed by surface imprinting on the surface of GO/Psf composite imprinted membranes (CIMs). The surface imprinting on the GO-Psf membrane was employed in order to enhance its selectivity towards polycyclic aromatic hydrocarbons (PAHs) in water. The CIMs were prepared through a process of phase inversion of a mixture of graphene oxide and polysulfone (Psf) in N-methylpyrrolidone (NMP). Fourier-transform spectroscopy (FT-IR) of the imprinted showed new peaks at 935 cm-1 and 1638 cm-1 indicating success in surface imprinting on the GO-Psf membrane. The CIM also showed improvement in flux from 8.56 LM-2 h-1 of unmodified polysulfone membrane to 15.3 LM-2 h-1 in the CIM, salt rejection increased from 57.2 ± 4.2% of polysulfone membrane to 76 ± 4.5%. The results obtained from the contact angle measurements showed a decrease with increase in GO content from 72 ± 2.7% of neat polysulfone membrane to 62.3 ± 2.1% of CIM indicating an improvement in surface hydrophilicity. The results from this study shows that, it is possible to improve the hydrophilicity of the membranes without affecting the performance of the membranes.

  15. A novel surface-confined glucaminium-based ionic liquid stationary phase for hydrophilic interaction/anion-exchange mixed-mode chromatography.

    Science.gov (United States)

    Qiao, Lizhen; Wang, Shuangyuan; Li, Hua; Shan, Yuanhong; Dou, Abo; Shi, Xianzhe; Xu, Guowang

    2014-09-19

    Glucaminium-based ionic liquids are a new class of recently developed ionic liquids and prepared by functionalizing the amine group of N-methyl-d-glucamine, which renders them good hydrophilicity due to the presence of the glucose structure and charged quaternary ammonium group. In the present study, a glucaminium-based ionic liquid N,N-diallyl-N-methyl-d-glucaminium bromide was synthesized and subsequently bonded to the surface of 3-mercaptopropyl modified silica materials through "thiol-ene" click chemistry. The obtained stationary phase was characterized by elemental analysis and infrared spectroscopy, and then packed as a HPLC column. A mixture of five nucleosides was used to characterize the separation performance of the obtained column under HILIC mode and the column efficiency was determined with cytidine as the test solute, reaching 80,000plates/m. Then, the retention behavior was evaluated by investigating the effect of various chromatographic factors on retention of different types of solutes, and the results revealed that the developed surface-confined glucaminium-based ionic liquid stationary phase exhibited a hydrophilic interaction/anion-exchange mixed-mode retention mechanism. Finally, two mixtures of nucleotides and flavonoids were separated on the glucaminium-based ionic liquid column, respectively under hydrophilic interaction and hydrophilic interaction/anion-exchange mixed-mode chromatography. In conclusion, the multimodal retention capabilities of the glucaminium-based ionic liquid column could offer a wider range of retention behavior and flexible selectivity toward polar and hydrophilic compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Transformation of a hydrophilic membrane into semi-super-hydrophobic based on self-assembly of stearic acid monolayer over induced nanostructures on the membrane surface

    Science.gov (United States)

    Madaeni, S. S.; Ghaemi, N.

    2007-11-01

    Both the chemical and structural properties of a surface determine the contact angle. For the formation of super-hydrophobic surfaces, modification of surface chemistry must be always combined with surface roughness enhancement. The used methods to make a super-hydrophobic surface are expensive and need very complicated equipments and cannot be scale up easily. In this study a simple and less expensive method was developed to transform a hydrophilic membrane into a semi-super-hydrophobic. In order to modify the membrane surface geometrically, the required needle-like rugosities were created by boiling the membrane in the water. The chemical modification of the roughened surface was created by the chemical adsorption and controlling the reaction time of stearic acid (STA) on the polymer of the membrane surface. Finally, by controlling the surface roughness, the concentration of the STA solution and duration of reaction time, a semi-super-hydrophobic membrane with the contact angle of 120° was prepared.

  17. 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.

  18. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Proteomic Response of Pseudomonas aeruginosa PAO1 Adhering to Solid Surfaces

    Directory of Open Access Journals (Sweden)

    Morgan Guilbaud

    2017-08-01

    Full Text Available Pseudomonas aeruginosa is a pathogenic micro-organism responsible for many hospital-acquired infections. It is able to adhere to solid surfaces and develop an immobilized community or so-called biofilm. Many studies have been focusing on the use of specific materials to prevent the formation of these biofilms, but the reactivity of the bacteria in contact to surfaces remains unknown. The aim of this study was to evaluate the impact of the abiotic surface on the physiology of adherent bacteria. Three different materials, stainless steel (SS, glass (G, and polystyrene (PS that were relevant to industrial or medical environments were characterized at the physicochemical level in terms of their hydrophobicity and roughness. We showed that SS was moderately hydrophilic and rough, potentially containing crevices, G was hydrophilic and smooth while PS was hydrophobic and smooth. We further showed that P. aeruginosa cells were more likely able to adhere to SS and G rather than PS surfaces under our experimental conditions. The physiological response of P. aeruginosa when adhering to each of these materials was then evaluated by global proteomic analysis. The abundance of 70 proteins was shown to differ between the materials suggesting that their abundance was modified as a function of the material to which bacteria adhered. Our data lead to enabling the identification of abundance patterns that appeared to be specific to a given surface. Taken together, our data showed that P. aeruginosa is capable of sensing and responding to a surface probably via specific programmes to adapt its physiological response accordingly.

  20. 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)

  1. 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)

  2. Drops and bubbles in contact with solid surfaces

    CERN Document Server

    Ferrari, Michele

    2012-01-01

    The third volume in a series dedicated to colloids and interfaces, Drops and Bubbles in Contact with Solid Surfaces presents an up-to-date overview of the fundamentals and applications of drops and bubbles and their interaction with solid surfaces. The chapters cover the theoretical and experimental aspects of wetting and wettability, liquid-solid interfacial properties, and spreading dynamics on different surfaces, including a special section on polymers. The book examines issues related to interpretation of contact angle from nano to macro systems. Expert contributors discuss interesting pec

  3. Physisorption of aromatic organic contaminants at the surface of hydrophobic/hydrophilic silica geosorbents: a B3LYP-D modeling study.

    Science.gov (United States)

    Rimola, Albert; Civalleri, Bartolomeo; Ugliengo, Piero

    2010-06-28

    The adsorption of benzene and benzene-1,4-diol on two all-silica surface models derived from the framework of sanidine mineral with either hydrophobic or hydrophilic properties has been studied by means of periodic calculations based on local Gaussian basis function and the B3LYP-D functional, which includes dispersion contribution as an empirical correction to the pure B3LYP energy. The aromatic molecules have been docked on different adsorption sites of the two surfaces using the electrostatic potential of the separate parts as a guide to ensure the best matching between electrophilic/nucleophilic regions. The inclusion of dispersion in the definition of the functional method dramatically affects both the intermolecular geometries and the adsorption energies, these latter being, in all cases, underestimated without the inclusion of the dispersive contribution. The adsorption of the aromatic molecules on the hydrophobic silica surface is dictated by dispersion and weak CH...O(Si)O interactions. The entity of the interaction for benzene on the hydrophilic surface is close to the value of the sublimation energy of the benzene molecular crystal, thus showing that adsorbate self-aggregation and adsorption to the silica surface are competing processes. For hydrophilic surfaces dispersion is still large despite the fact that adsorption energies are almost doubled with respect to the hydrophobic surface due to H-bonding interactions through either SiOH...pi (benzene case) or SiOH...OH (benzene-1,4-diol case). The computed infrared spectra of the adsorbed molecules reveal small perturbations in the CH, CCH and CCC ring modes, which are sensitive to the adsorbate/adsorbent features, so that these bands can be used as fingerprints for the interpretation of experimental spectra. The present work may contribute to a better understanding of the sorption of typical organic contaminants in common earth's inorganic soils, which is of relevance for environmental concerns.

  4. The role of bone debris in early healing adjacent to hydrophilic and hydrophobic implant surfaces in man.

    Science.gov (United States)

    Bosshardt, Dieter D; Salvi, Giovanni E; Huynh-Ba, Guy; Ivanovski, Saso; Donos, Nikolaos; Lang, Niklaus P

    2011-04-01

    To evaluate morphologically and morphometrically the sequential healing and osseointegration events at moderately rough implant surfaces with and without chemical modification. Particularly the role of bone debris in initiating bone formation was emphasized. Solid, screw-type cylindrical titanium implants (SSI) (n=49), 4 mm long and 2.8 mm wide, with either chemically modified (SLActive(®)) or sandblasted and acid-etched (SLA(®)) surface configurations were surgically installed in the retromolar region of 28 human volunteers. After 7, 14, 28 and 42 days of submerged healing, the devices were retrieved with a trephine. Histologic ground sections were prepared and histomorphometrically analyzed. Linear measurements determined fractions of old bone (OBIC), new bone (NBIC), soft tissue (ST) and bone debris (BD) in contact with the SSI surfaces. Healing was uneventful at all installation sites. Sixty-one percent of all devices were suitable for morphometric analyses. All implant surfaces were partially coated with bone debris and new bone formation was observed as early as 7 days after installation. There was a gradual increase in NBIC, whereas OBIC, ST and BD progressively decreased over time. NBIC after 2 and 4 weeks was higher on SLActive(®) than on SLA(®) surfaces, albeit statistically not significant. The BD : ST ratio changed significantly from 7 to 42 days (from 50 : 50 to 10 : 90 for SLActive(®); from 38: 62 to 10 : 90 for SLA(®)) (Fisher's exact test, Psurface was gradually resorbed. The decrease in BD : ST ratio suggests that bone debris, created during implant installation and adhering to moderately rough surfaces, significantly contributed to the initiation of bone deposition and mediated the connection between the old bone and the new bone on the implant surface. © 2011 John Wiley & Sons A/S.

  5. Improvement of the surface hydrophilic properties of naproxen particles with addition of hydroxypropylmethyl cellulose and sodium dodecyl sulphate: In vitro and in vivo studies.

    Science.gov (United States)

    García-Herrero, Víctor; Torrado, Carlos; García-Rodríguez, Juan José; López-Sánchez, Alicia; Torrado, Susana; Torrado-Santiago, Santiago

    2017-08-30

    In this study, a new surface-modified naproxen was developed to enhance brain concentration in acute migraine treatment. Fast-dissolving naproxen granules were made by mixing hydroxypropylmethylcellulose (HPMC) sodium dodecyl sulphate (SDS) and sodium croscarmellose with micronized naproxen particles. The aim of this study was to evaluate the effect of adding proportions of SDS to the HPMC film caused changes in the polymer chains of the HPMC, producing a new hydrophilic HPMC-SDS structure. These formulations with different HPMC/SDS ratios were characterised using electron microscopy (SEM), powder X-ray diffraction (PXRD), and differential scanning calorimetry (DSC). SDS 10% (w/w) produced a highly hydrophilic HPMC-SDS structure on the surface of the naproxen microparticles. The fast dissolution granules (SF-10%) showed a significant improvement in the dissolution rate of naproxen. Pharmacokinetic studies were conducted with mice, showing an improvement of Cmax (1.38 and 1.41-fold) and AUC0-2h (30% and 10% higher) for plasma and brain samples compared to the reference naproxen suspension. The faster Tmax ratio for SF-10% may be related to increased hydration in the gastrointestinal environment, enabling the drug to permeate the gastrointestinal hydration layer more easily due to the presence of the hydrophilic HPMC-SDS structure in the formulation. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Poly(ethylene glycol)-grafted cyclic acetals based polymer networks with non-water-swellable, biodegradable and surface hydrophilic properties.

    Science.gov (United States)

    Yin, Ruixue; Zhang, Nan; Wu, Wentao; Wang, Kemin

    2016-05-01

    Cyclic acetals based biomaterial without acidic products during hydrolytic degradation is a promising candidate for tissue engineering applications; however, low hydrophilicity is still one limitation for its biomedical application. In this work, we aim to achieve non-water-swellable cyclic acetal networks with improved hydrophilicity and surface wettability by copolymerization of cyclic acetal units based monomer, 5-ethyl-5-(hydroxymethyl)-β,β-dimethyl-1, 3-dioxane-2-ethanol diacrylate (EHD) and methoxy poly(ethylene glycol) monoacrylate (mPEGA) under UV irradiation, to avoid swelling of conventional hydrogels which could limit their applicability in particular of the mechanical properties and geometry integrity. Various EHD/mPEGA networks were fabricated with different concentrations of mPEGA from 0 to 30%, and the results showed photopolymerization behavior, mechanical property and thermal stability could not be significantly affected by addition of mPEGA, while the surface hydrophilicity was dramatically improved with the increase of mPEGA and could achieve a water contact angle of 37° with 30% mPEGA concentration. The obtained EHD/mPEGA network had comparative degradation rate to the PECA hydrogels reported previously, and MTT assay indicated it was biocompatible to L929 cells. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Mallampati, Srinivasa Reddy, E-mail: srireddys@ulsan.ac.kr; Heo, Je Haeng; Park, Min Hee

    2016-04-05

    Highlights: • Nanometallic Ca/CaO treatment significantly enhanced PVC surface hydrophilicity. • The contact angle of PVC significantly decreased compared to other E-waste plastics. • 100% of PVC was selectively separated with 96.4% purity from E-waste plastics. • SEM/XPS results indicated an oxidative degradation of chlorides on the PVC surface. • Hybrid treatment with nanometallic Ca/CaO and froth flotation is effective. - Abstract: 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 100 rpm 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 20.5 wt% 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.

  8. 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. © 2015 Wiley Periodicals, Inc.

  9. 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

    to those found on an implanted device. We have used the method to evaluate the biofilm forming capacity of clinically isolated Escherichia coli on silicone rubber and on silicone rubber containing a hydrophilic coating. It was found that the surface chemistry influenced the colonization of the isolates...

  10. Solid surfaces, interfaces and thin films

    CERN Document Server

    Lüth, Hans

    2015-01-01

    This book emphasises both experimental and theoretical aspects of surface, interface and thin-film physics. As in previous editions the preparation of surfaces and thin films, their atomic and morphological structure, their vibronic and electronic properties as well as fundamentals of adsorption are treated. Because of their importance in modern information technology and nanostructure research, particular emphasis is paid to electronic surface and interface states, semiconductor space charge layers and heterostructures. A special chapter of the book is devoted to collective phenomena at interfaces and in thin films such as superconductivity and magnetism. The latter topic includes the meanwhile important issues giant magnetoresistance and spin-transfer torque mechanism, both effects being of high interest in information technology. In this new edition, for the first time, the effect of spin-orbit coupling on surface states is treated. In this context the class of the recently detected topological insulators,...

  11. On the roughening of solid surfaces

    Science.gov (United States)

    Rys, Franz S.

    1986-12-01

    Two roughening phenomena are discussed. The kink-driven line roughening of high-indexed surfaces (such as fcc(113), (115) and (117), discussed in various papers recently) is presumably undergoing an Ising-type transition in contrast to the step-driven surface roughening which shows either a Kosterlitz-Thouless-type infinite-order phase transition, or, depending on the step energy parameters, a smooth cross-over only.

  12. 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.

  13. 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

  14. A simple sample preparation approach based on hydrophilic solid-phase extraction coupled with liquid chromatography-tandem mass spectrometry for determination of endogenous cytokinins.

    Science.gov (United States)

    Cai, Bao-Dong; Zhu, Jiu-Xia; Shi, Zhi-Guo; Yuan, Bi-Feng; Feng, Yu-Qi

    2013-12-30

    Cytokinins (CKs), a vital family of phytohormones, play important roles in the regulation of shoot and root development. However, the quantification of CKs in plant samples is frequently affected by the complex plant matrix. In the current study, we developed a simple, rapid and efficient hydrophilic interaction chromatography-solid phase extraction (HILIC-SPE) method for CKs purification. CKs were extracted by acetonitrile (ACN) followed by HILIC-SPE (silica as sorbents) purification. The extraction solution of plant samples could be directly applied to HILIC-SPE without solvent evaporation step, which simplified the analysis process. Moreover, with HILIC chromatographic retention mechanism, the hydrophobic co-extracted impurities were efficiently removed. Subsequently, CKs were separated by RPLC, orthogonal to the HILIC pretreatment process, and detected by tandem mass spectrometry. The method exhibits high specificity and recovery yield (>77.0%). Good linearities were obtained for all eight CKs ranging from 0.002 to 100ngmL(-1) with correlation coefficients (r) higher than 0.9927. The limits of detection (LODs, signal/noise=5) for the CKs were between 1.0 and 12.4pgmL(-1). Reproducibility of the method was evaluated by intra-day and inter-day measurements and the results showed that relative standard deviations (RSDs) were less than 10.5%. Employing this method, we successfully quantified six CKs in 20mg Oryza sativa leaves and the method was also successfully applied to Brassica napus (flower and leaves). Copyright © 2013 Elsevier B.V. All rights reserved.

  15. Hollow porous ionic liquids composite polymers based solid phase extraction coupled online with high performance liquid chromatography for selective analysis of hydrophilic hydroxybenzoic acids from complex samples.

    Science.gov (United States)

    Dai, Xingping; Wang, Dongsheng; Li, Hui; Chen, Yanyi; Gong, Zhicheng; Xiang, Haiyan; Shi, Shuyun; Chen, Xiaoqing

    2017-02-10

    Polar and hydrophilic properties of hydroxybenzoic acids usually made them coelute with interferences in high performance liquid chromatography (HPLC) analysis. Then selective analysis of them was necessary. Herein, hollow porous ionic liquids composite polymers (PILs) based solid phase extraction (SPE) was firstly fabricated and coupled online with HPLC for selective analysis of hydroxybenzoic acids from complex matrices. Hollow porous PILs were firstly synthesized using Mobil Composition of Matter No. 48 (MCM-48) spheres as sacrificial support, 1-vinyl-3-methylimidazolium chloride (VMIM(+)Cl(-)) as monomer, and ethylene glycol dimethacrylate (EGDMA) as cross-linker. Various parameters affecting synthesis, adsorption and desorption behaviors were investigated and optimized. Steady-state adsorption studies showed the resulting hollow porous PILs exhibited high adsorption capacity, fast adsorption kinetics, and excellent specific adsorption. Subsequently, the application of online SPE system was studied by selective analysis of protocatechuic acid (PCA), 4-hydroxybenzoic acid (4-HBA), and vanillic acid (VA) from Pollen Typha angustifolia. The obtained limit of detection (LOD) varied from 0.002 to 0.01μg/mL, the linear range (0.05-5.0μg/mL) was wide with correlation coefficient (R) from 0.9982 to 0.9994, and the average recoveries at three spiking levels ranged from 82.7 to 102.4%, with column-to-column relative standard deviation (RSD) below 8.1%. The proposed online method showed good accuracy, precision, specificity and convenience, which opened up a universal and efficient route for selective analysis of hydroxybenzoic acids from complex samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. 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.

  17. Solid-solid contacts due to surface roughness and their effects on suspension behaviour.

    Science.gov (United States)

    Davis, Robert H; Zhao, Yu; Galvin, Kevin P; Wilson, Helen J

    2003-05-15

    Solid-solid contacts due to microscopic surface roughness in viscous fluids were examined by observing the translational and rotational behaviours of a suspended sphere falling past a lighter sphere or down an inclined surface. In both cases, a roll-slip behaviour was observed, with the gravitational forces balanced by not only hydrodynamic forces but also normal and tangential solid-solid contact forces. Moreover, the nominal separation between the surfaces due to microscopic surface roughness elements is not constant but instead varies due to multiple roughness scales. By inverting the system, so that the heavy sphere fell away from the lighter sphere or the plane, it was found that the average nominal separation increases with increasing angle of inclination of the plane or the surface of the lighter sphere from horizontal; the larger asperities lift the sphere up from the opposing surface and then gravity at large angles of inclination is too weak to pull the sphere back down to the opposing surface before another large asperity is encountered. The existence of microscopic surface roughness and solid-solid contacts is shown to modify the rheological properties of suspensions. For example, the presence of compressive, but not tensile, contact forces removes the reversibility of sphere-sphere interactions and breaks the symmetry of the particle trajectories. As a result, suspensions of rough spheres exhibit normal stress differences that are absent for smooth spheres. For the conditions studied, surface roughness reduces the effective viscosity of a suspension by limiting the lubrication resistance during near-contact motion, and it also modifies the suspension microstructure and hydrodynamic diffusivity.

  18. Solid colloids with surface-mobile linkers.

    Science.gov (United States)

    van der Meulen, Stef A J; Helms, Gesa; Dogterom, Marileen

    2015-06-17

    In this report we review the possibilities of using colloids with surface mobile linkers for the study of colloidal self-assembly processes. A promising route to create systems with mobile linkers is the use of lipid (bi-)layers. These lipid layers can be either used in the form of vesicles or as coatings for hard colloids and emulsion droplets. Inside the lipid bilayers molecules can be inserted via membrane anchors. Due to the fluidity of the lipid bilayer, the anchored molecules remain mobile. The use of different lipid mixtures even allows creating Janus-like particles that exhibit directional bonding if linkers are used which have a preference for a certain lipid phase. In nature mobile linkers can be found e.g. as receptors in cells. Therefore, towards the end of the review, we also briefly address the possibility of using colloids with surface mobile linkers as model systems to mimic cell-cell interactions and cell adhesion processes.

  19. Structure of Solids Surfaces in Wear Situations.

    Science.gov (United States)

    1984-10-17

    lactones , respectively. As pointed out by Greenler 12J, the most intense emission bands from a material adsorbed in a thin layer on a metal surface...peroxides are formed instead of hydroper-.,. .," ", oxides. The decomposition of these peroxides then leads to unsaturates , aldehydes, ketones and...around 1100 cm-1 (OH and unsaturation ) and at 730 cm-1 (CH2 rock). weeIt is clear that such analyses are difficult, but can yield a welthof information

  20. Surface modification of solid state gas sensors

    CERN Document Server

    Morris, L

    2000-01-01

    mechanism of the room temperature CO response of SnO sub 2 decorated with small Pt particles was refined. In this case Pt was applied by common impregnation techniques. The conductivity was shown to be controlled by the surface state of the Pt. The CO response at room temperature was found to be specific to the presence of Pt(ll) species. The mechanism was assigned to CO chemisorption onto Pt(ll), resulting in charge transfer, measured as conductivity increase. The samples were characterized by XPS, TPD, SEM, mass spectrometry and electrical measurements. Comparison of the results presented for Pt decorated BaSn sub 0 sub . sub 9 sub 7 Sb sub 0 sub . sub 0 sub 3 O sub 3 and BaFeO sub 3 demonstrated the phenomenon to be general providing that Pt particles act as surface traps, controlling the conductivity. The phenomenon of electrical conductivity being controlled by the chemical state of a surface grafted reactive centre, resulting in a room temperature gas response, is demonstrated. The reactive centres can ...

  1. Estimation of solid-liquid interfacial tension using curved surface of a soft solid.

    Science.gov (United States)

    Mondal, Subrata; Phukan, Monmee; Ghatak, Animangsu

    2015-10-13

    Unlike liquids, for crystalline solids the surface tension is known to be different from the surface energy. However, the same cannot be said conclusively for amorphous materials like soft cross-linked elastomers. To resolve this issue we have introduced here a direct method for measuring solid-liquid interfacial tension by using the curved surface of a solid. In essence, we have used the inner surface of tiny cylindrical channels embedded inside a soft elastomeric film for sensing the effect of the interfacial tension. When a liquid is inserted into the channel, because of wetting-induced alteration in interfacial tension, its thin wall deflects considerably; the deflection is measured with an optical profilometer and analyzed using the Föppl-von Kármán equation. We have used several liquids and cross-linked poly(dimethylsiloxane) as the solid to show that the estimated values of the solid-liquid interfacial tension matches with the corresponding solid-liquid interfacial energy reasonably well.

  2. Vibrational lineshapes of adsorbates on solid surfaces

    Science.gov (United States)

    Ueba, H.

    A review is presented of the current activity in vibrational spectroscopy of adsorbates on metal surfaces. A brief introduction of the representative spectroscopies is given to demonstrate the rich information contained in vibrational spectra, which are characterized by their intensity, peak position and width. Analysis of vibrational spectra enables us to gain the deep insight into not only the local character of adsorption site or geometry, but also the dynamical interaction between the adsorbates or between the adsorbate and the substrate. Some recent instructive experimental results, mostly of a CO molecule adsorbed on various metal surfaces, are accompanied by the corresponding theoretical recipe for vibrational excitation mechanisms. Wide spread experimental results of the C-O stretching frequency of CO adsorbed on metal surfaces are discussed in terms of the chemical effect involving the static and dynamic charge transfers between the chemisorbed CO and metal, and also of the electrostatic dipole-dipole interaction between the molecules. The central subject of this review is directed to the linshapes characterized by the vibrational relaxation processes of adsorbates. A simple and transparent model is introduced to show that the characteristic decay time of the correlation function for the vibrational coordinates is the key quantity to determine the spectral lineshapes. Recent experimental results focused on a search for an intrinsic broadening mechanism are reviewed in the light of the so-called T1 (energy) and T2 (phase) relaxation processesof the vibrational excited states of adsorbates. Those are the vibrational energy dissipation into the elementary excitation, such as phonons or electron-hole pairs in the metal substrate, and pure dephasing due to the energy exchange with the sorroundings. The change of width and frequency by varying the experimental variables, such as temperature or isotope effect, provides indispensable knowledge for the dynamical

  3. Loading of titanium implants with hydrophilic endosteal surface 3 weeks after insertion: clinical and radiological outcome of a 12-month prospective clinical trial.

    Science.gov (United States)

    Hinkle, Robert M; Rimer, Stephen R; Morgan, Michael H; Zeman, Paul

    2014-08-01

    The aim of this study was to test whether early loading (21 days after insertion) of implants with a hydrophilic surface is safe and reliable in a general clinical practice setting. This was a prospective multicenter clinical trial conducted in 3 independent surgical practices. Patients were selected according to predefined inclusion and exclusion criteria. Implants were placed in posterior regions into healed alveoli and native bone using a 1-stage (unsubmerged) surgical protocol. Loading was to be performed 21 days thereafter. Patients were followed clinically and radiographically for 1 year. Twenty-one patients who received 23 implants were followed for 1 year. None of the osseointegrated implants were lost. One broken provisional crown was reported during the trial period. The crestal bone remained remarkably stable (ie, approximately 1 mm below the microgap). The most coronal bone-to-implant contact stabilized at the level of the first implant thread just beneath the machined collar. Within the limitations of this clinical study, the authors confirmed that loading of implants with a hydrophilic surface 3 weeks after placement appears to be a safe and predictable treatment option. No crestal bone loss was observed 1 year after implant placement. Therefore, it appears that crestal bone loss is dependent on the design features of the specific implant line. Copyright © 2014 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

  4. Tandem solid phase extraction followed by online trapping-hydrophilic interaction chromatography-tandem mass spectrometry for sensitive detection of endogenous cytokinins in plant tissues.

    Science.gov (United States)

    Liu, Zhao; Yuan, Bi-Feng; Feng, Yu-Qi

    2012-01-01

    Cytokinins (CKs) are a group of plant hormones that play pivotal roles at low concentration in plant growth, development and regulatory pathways. In order to study the function, metabolism and signal transduction of CKs, high performance analytical techniques are required for determination of their endogenous levels. To develop a highly sensitive, selective and reliable method for identification and quantification of CKs by employing a tandem solid phase extraction (SPE)-online trapping-hydrophilic interaction chromatography (HILIC)-MS/MS method. The extraction was performed firstly with tandem SPE containing a C(18) cartridge and a silica@C(8) /SO(3) H cartridge. After CKs were eluted from the silica@C(8)/SO(3) H cartridge, the desorption solvent was concentrated and redissolved in H(2)O and then injected into the online trapping-HILIC-MS/MS system with (Poly(MAA-co-EGDMA)) monolith as the trapping column. Subsequently, trapping, washing, desorption, separation and detection were accomplished automatically on the system. Good linearities were obtained for eight cytokinins with correlation coefficients (R(2)) > 0.9964. The limits of detection (LOD; S:N = 3) for the targets ranged from 0.042 to 1.6 pg/mL. Reproducibility of the method was evaluated with intraday and interday relative standard deviations (RSDs) less than 13.4% and the recoveries ranged from 77.3% to 116.3%. The results showed that the LOD of the analytical method were at least one order of magnitude lower compared with other previously reported methods. Furthermore, only 20 mg of plant tissues were required for the quantitative analysis of the major CKs, which is, to the best of our knowledge, the smallest amount reported so far for the determination of endogenous CKs in plant tissues. The tandem SPE-online trapping-HILIC-MS/MS method developed in current study provides a powerful tool for the convenient and highly sensitive quantification of the major CKs in plant tissue. Copyright © 2012 John

  5. Reprint of ;Surface-environment effects in spin crossover solids;

    Science.gov (United States)

    Gudyma, Iu.; Maksymov, A.

    2017-12-01

    The impact of surface effects on thermal induced spin crossover phenomenon is a subject of a broad and current interest. Using the modified Ising-like model of spin crossover solids with the ligand field as function of the molecule' positions and random component on surface by means of Metropolis Monte Carlo algorithm the thermal spin transition curves were calculated. The analysis of spin configuration during transition gives a general idea about contribution of molecules from the surface and inside the lattice into resulting magnetization of the systems. The behavior of hysteresis loop for various surface coupling and fluctuations strength has been described.

  6. On the Interaction of Capillary Shapes with Solid Surfaces

    NARCIS (Netherlands)

    Musterd, M.

    2015-01-01

    Control over the interaction of droplets with solid surfaces is commonplace in nature. Famous examples are the water-shedding capabilities of the lotus leaf and the water-harvesting skin of certain types of beetles. To date, this type of control remains a challenge in engineering applications.

  7. The effects of viscosity on sound radiation near solid surfaces

    DEFF Research Database (Denmark)

    Morfey, C.L.; Sorokin, Sergey; Gabard, G.

    2012-01-01

    Although the acoustic analogy developed by Lighthill, Curle, and Ffowcs Williams and Hawkings for sound generation by unsteady flow past solid surfaces is formally exact, it has become accepted practice in aeroacoustics to use an approximate version in which viscous quadrupoles are neglected. Her...

  8. COUPLING OF LIPOPOLYSACCHARIDE-DERIVED CARBOHYDRATES ONTO SOLID SURFACES

    DEFF Research Database (Denmark)

    2000-01-01

    The present invention provides a method for immobilising a polysaccharide (PS) to a solid surface, said polysaccharide having a keto-carboxy group (-C(=O)-COOH) or a ketal or hemiketal group corresponding thereto, e.g. derived from KDO (2-keto-3-deoxy-D-mannooctonic acid), the method comprising t...

  9. Theory of flame spread above solids. [fuel exothermic surface reactions

    Science.gov (United States)

    Sirignano, W. A.

    1974-01-01

    A theory for flame spread above a solid fuel is presented. The special case is considered whereby the oxidation is an exothermic surface reaction. The spreading rate is predicted as a function of the thermochemical properties, fuel-bed thickness, and convective velocity. Also, the theory predicts temperature, mass fraction, and heat flux as a function of position.

  10. Measuring forces and spatiotemporal evolution of thin water films between an air bubble and solid surfaces of different hydrophobicity.

    Science.gov (United States)

    Shi, Chen; Cui, Xin; Xie, Lei; Liu, Qingxia; Chan, Derek Y C; Israelachvili, Jacob N; Zeng, Hongbo

    2015-01-27

    A combination of atomic force microscopy (AFM) and reflection interference contrast microscopy (RICM) was used to measure simultaneously the interaction force and the spatiotemporal evolution of the thin water film between a bubble in water and mica surfaces with varying degrees of hydrophobicity. Stable films, supported by the repulsive van der Waals-Casimir-Lifshitz force were always observed between air bubble and hydrophilic mica surfaces (water contact angle, θ(w) bubble attachment occurred on hydrophobized mica surfaces. A theoretical model, based on the Reynolds lubrication theory and the augmented Young-Laplace equation including the effects of disjoining pressure, provided excellent agreement with experiment results, indicating the essential physics involved in the interaction between air bubble and solid surfaces can be elucidated. A hydrophobic interaction free energy per unit area of the form: WH(h) = -γ(1 - cos θ(w))exp(-h/D(H)) can be used to quantify the attraction between bubble and hydrophobized solid substrate at separation, h, with γ being the surface tension of water. For surfaces with water contact angle in the range 45° bubble and hydrophobic surfaces, and provided a feasible method for synchronous measurements of the interaction forces with sub-nN resolution and the drainage dynamics of thin films down to nm thickness.

  11. Surface and defect morphologies in anisotropic elastic and piezoelectric solids

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Huajian; Barnett, D.M. [Stanford Univ., CA (United States)

    1996-12-31

    The authors investigate issues related to the equilibrium and stability of surface and line defect morphologies in both piezoelectric and anisotropic elastic solids. Following their previous efforts which established that mechanical stresses in purely elastic solids can promote instability of an initially flat surface with respect to surface roughening, they show that the (initially flat) interface between two dissimilar piezoelectric solids can be unstable when subjected to coupled electromechanical loading. Quite recent cross-sectional observations of electrodeposited thin films by Japanese and British researchers provide experimental confirmation of these predictions. The authors also investigate the occurrence of equilibrium arrangements (zero Peach-Koehler force arrangements) of line defects (dislocations) in anisotropic elastic crystals in the absence of externally applied stresses. Contrary to prevailing opinion, equilibrium arrangements of dislocations under no externally applied stresses appear to be the rule rather than the exception. The existence of such {open_quotes}zero stress arrangements{close_quotes} is fundamental to developing micromechanical models of plastically deforming solids.

  12. Improvement in surface hydrophilicity and resistance to deformation of natural leather through O{sub 2}/H{sub 2}O low-temperature plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    You, Xuewei; Gou, Li, E-mail: gouli@scu.edu.cn; Tong, Xingye

    2016-01-01

    Graphical abstract: - Highlights: • O{sub 2}/H{sub 2}O can increase oxygen concentration in the plasma compared to the pure O{sub 2} atmosphere. • Pores at the surface of natural leather became larger and deeper with enhanced permeability of water. • The initial water contact angle was about 21°. • Its preferable surface hydrophilicity kept for 3 days, which gives guidance for next process. • The elongation of the treated sample for 10 min was twice as large as that of the untreated sample. - Abstract: The natural leather was modified through O{sub 2}/H{sub 2}O 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 O{sub 2}/H{sub 2}O 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.

  13. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Effect of low-concentration rhamnolipid on transport of Pseudomonas aeruginosa ATCC 9027 in 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

    2016-01-01

    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 or 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 rhamnolipid-regulated cell surface hydrophobicity presented as bacterial-adhesion-to-hydrocarbon (BATH) rate of cells (R2 = 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. PMID:26722821

  15. Water drop impact onto oil covered solid surfaces

    Science.gov (United States)

    Chen, Ningli; Chen, Huanchen; Amirfazli, Alidad

    2016-11-01

    Droplet impact onto an oily surface can be encountered routinely in industrial applications; e.g., in spray cooling. It is not clear from literature what impact an oil film may have on the impact process. In this work, water drop impact onto both hydrophobic (glass) and hydrophilic (OTS) substrates which were covered by oil films (silicone) of different thickness (5um-50um) and viscosity (5cst-100cst) were performed. The effects of drop impact velocity, film thickness, and viscosity of the oil film and wettability of the substrate were studied. Our results show that when the film viscosity and impact velocity is low, the water drop deformed into the usual disk shape after impact, and rebounded from the surface. Such rebound phenomena disappears, when the viscosity of oil becomes very large. With the increase of the impact velocity, crown and splashing appears in the spreading phase. The crown and splashing behavior appears more easily with the increase of film thickness and decrease of its viscosity. It was also found that the substrate wettability can only affect the impact process in cases which drop has a large Webber number (We = 594), and the film's viscosity and thickness are small. This work was support by National Natural Science Foundation of China and the Project Number is 51506084.

  16. Early loading of titanium dental implants with an intra-operatively conditioned hydrophilic implant surface after 21 days of healing.

    Science.gov (United States)

    Hicklin, Stefan Paul; Schneebeli, Esther; Chappuis, Vivianne; Janner, Simone Francesco Marco; Buser, Daniel; Brägger, Urs

    2016-07-01

    The aim of the present observational medical device performance study was to test whether implants with an intra-operatively conditioned hydrophilic surface can be safely reconstructed when applying an early loading protocol after 21 days in partially edentulous posterior mandibles. Partially edentulous patients with missing teeth in the posterior mandible were recruited. Immediately after implant placement, the implant position was indexed using a pickup impression technique. ISQ values were measured after 21 days of healing. When ISQ values were ≥70, the implants were directly restored with provisional reconstructions in occlusal contact allowing an early loading protocol. ISQ values were repeated again at 1, 3, and 6 months postloading. Clinical parameters (mPLI, mSBI, PPD, DIM, and CAL) were assessed. Standardized periapical radiographs were obtained after surgery, at implant loading and 3 and 6 months later. Changes over time were analyzed for statistical significance using the nonparametric method by Brunner & Langer (SAS Proc Mixed). Fifteen partially edentulous patients with healed sites in the posterior mandible received 20 implants. All implants healed uneventfully. At 21 days, all implants achieved an ISQ value of ≥70 (mean of 3 measurements) and were reconstructed at this time point with provisionals. ISQ values showed a gradual increase from baseline to 3 and 6 months postloading. The assessment of clinical parameters revealed stable tissue integration. The evaluation of the radiographs showed that 3 and 6 months after loading the median mesial and distal marginal bone levels had stabilized at the border between the rough surface and the 1-mm machined implant collar. Functional occlusal loading of implants with a hydrophilic, moderately rough endosseal surface 3 weeks after placement appears to be a safe and predictable treatment option in healed sites in the posterior mandible without need of bone augmentation procedures. © 2015 John

  17. Particle engineering in pharmaceutical solids processing: surface energy considerations.

    Science.gov (United States)

    Williams, Daryl R

    2015-01-01

    During the past 10 years particle engineering in the pharmaceutical industry has become a topic of increasing importance. Engineers and pharmacists need to understand and control a range of key unit manufacturing operations such as milling, granulation, crystallisation, powder mixing and dry powder inhaled drugs which can be very challenging. It has now become very clear that in many of these particle processing operations, the surface energy of the starting, intermediate or final products is a key factor in understanding the processing operation and or the final product performance. This review will consider the surface energy and surface energy heterogeneity of crystalline solids, methods for the measurement of surface energy, effects of milling on powder surface energy, adhesion and cohesion on powder mixtures, crystal habits and surface energy, surface energy and powder granulation processes, performance of DPI systems and finally crystallisation conditions and surface energy. This review will conclude that the importance of surface energy as a significant factor in understanding the performance of many particulate pharmaceutical products and processes has now been clearly established. It is still nevertheless, work in progress both in terms of development of methods and establishing the limits for when surface energy is the key variable of relevance.

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

    Science.gov (United States)

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

    2016-07-01

    Here, we review the principle and applications of two recently developed methods: the capillary meniscus dynamometry (CMD) for measuring the surface tension of bubbles/drops, and the capillary bridge dynamometry (CBD) for quantifying the bubble/drop adhesion to solid surfaces. Both methods are based on a new data analysis protocol, which allows one to decouple the two components of non-isotropic surface tension. For an axisymmetric non-fluid interface (e.g. bubble or drop covered by a protein adsorption layer with shear elasticity), the CMD determines the two different components of the anisotropic surface tension, σs and σφ, which are acting along the "meridians" and "parallels", and vary throughout the interface. The method uses data for the instantaneous bubble (drop) profile and capillary pressure, but the procedure for data processing is essentially different from that of the conventional drop shape analysis (DSA) method. In the case of bubble or drop pressed against a substrate, which forms a capillary bridge, the CBD method allows one to determine also the capillary-bridge force for both isotropic (fluid) and anisotropic (solidified) adsorption layers. The experiments on bubble (drop) detachment from the substrate show the existence of a maximal pulling force, Fmax, that can be resisted by an adherent fluid particle. Fmax can be used to quantify the strength of adhesion of bubbles and drops to solid surfaces. Its value is determined by a competition of attractive transversal tension and repulsive disjoining pressure forces. The greatest Fmax values have been measured for bubbles adherent to glass substrates in pea-protein solutions. The bubble/wall adhesion is lower in solutions containing the protein HFBII hydrophobin, which could be explained with the effect of sandwiched protein aggregates. The applicability of the CBD method to emulsion systems is illustrated by experiments with soybean-oil drops adherent to hydrophilic and hydrophobic substrates in

  19. Surface-environment effects in spin crossover solids

    Energy Technology Data Exchange (ETDEWEB)

    Gudyma, Iu., E-mail: yugudyma@gmail.com; Maksymov, A.

    2017-06-15

    Highlights: • The spin-crossover nanocrystals were described by modified Ising-like model. • The ligand field on the surface is a function of external fluctuations. • The thermal hysteresis with surface and bulk interactions of the lattice was studied. • The system behavior with fluctuating ligand field on the surface was examined. • The fluctuations enlarge the hysteresis, but smaller surface interaction narrows it. - Abstract: The impact of surface effects on thermal induced spin crossover phenomenon is a subject of a broad and current interest. Using the modified Ising-like model of spin crossover solids with the ligand field as function of the molecule’ positions and random component on surface by means of Metropolis Monte Carlo algorithm the thermal spin transition curves were calculated. The analysis of spin configuration during transition gives a general idea about contribution of molecules from the surface and inside the lattice into resulting magnetization of the systems. The behavior of hysteresis loop for various surface coupling and fluctuations strength has been described.

  20. Wear-resistant rose petal-effect surfaces with superhydrophobicity and high droplet adhesion using hydrophobic and hydrophilic nanoparticles.

    Science.gov (United States)

    Ebert, Daniel; Bhushan, Bharat

    2012-10-15

    Surfaces exhibiting the so-called "petal effect" (superhydrophobicity with high droplet adhesion) have potential for applications such as the transport of small volumes of liquid. It is known that the microstructure pitch value and nanostructure density are important in achieving this effect, both in rose petals themselves and in synthetic petal-effect surfaces. However, the effect of the surface energy of materials on these values has not been systematically studied. In addition, wear resistance, which is critical for industrial applications, has rarely been examined for petal-effect surfaces. In this study, surfaces of varying microstructure pitch and nanostructure density were fabricated by depositing ZnO nanoparticles onto micropatterned substrates. The prepared surfaces were then modified with octadecylphosphonic acid (ODP) in order to hydrophobize the ZnO nanoparticles. The wettability of the surfaces was characterized both before and after ODP modification. The effect of hydrophobizing the nanostructure was examined with regards to the values of microstructure pitch and nanostructure density necessary to achieve the petal effect. In addition, to study wear resistance for industrial applications, a wear experiment was performed using an atomic force microscope (AFM). Copyright © 2012 Elsevier Inc. All rights reserved.

  1. Enhancement of dissolution of Telmisartan through use of solid dispersion technique surface solid dispersion

    Directory of Open Access Journals (Sweden)

    Bhumika Patel

    2012-01-01

    Full Text Available The present study was aimed to increase the solubility of the poorly water soluble drug Telmisartan by using Surface solid dispersion (SSD made of polymers like Poloxamer 407, PEG 6000 by Solvent evaporation method. The drug was solubilized by surfactants and/or polymers then adsorbed onto the surface of extremely fine carriers to increase its surface area and to form the SSD which give the more Surface area for absorption of the drug. A 2 2 full factorial design was used to investigate for each carrier the joint influence of formulation variables: Amount of carrier and adsorbent. Saturation solubility studies shows the improvement in solubility of drug batch SSD 8 give more solubility improvement than the other batch, in-vitro dissolution of pure drug, physical mixtures and SSDs were carried out in that SSDs were found to be effective in increasing the dissolution rate of Telmisartan in form of SSD when compared to pure drug. Also FT-IR spectroscopy, differential scanning calorimetry and X-ray diffractometry studies were carried out in order to characterize the drug and Surface solid dispersion. Furthermore, both DSC and X-ray diffraction showed a decrease in the melting enthalpy and reduced drug crystallinity consequently in SSDs. However, infrared spectroscopy revealed no drug interactions with the carriers.

  2. 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. Copyright 2000 John Wiley & Sons, Inc.

  3. A numerical simulation method for analyzing the thermal improvement effect of super-hydrophilic photocatalyst-coated building surfaces with water film on the urban/built environment

    Energy Technology Data Exchange (ETDEWEB)

    He, Jiang; Hoyano, Akira [Interdisciplinary Graduate School, Tokyo Institute of Technology, 4259-G5-2 Nagatsuta-cho, Midori-ku, Yokohama 226-8502 (Japan)

    2008-07-01

    As an application of the super-hydrophilicity of a photocatalyst (TiO{sub 2}) coating, buildings are cooled by sprinkling water on their external surfaces coated with TiO{sub 2}. This is a new cooling technology that was recently developed in Japan. In order to make better use of this cooling system, quantitative prediction and evaluation of the cooling effect on the urban/built environment is required during design. In an attempt to provide a computer-aided simulation tool for supporting the above-mentioned design, we introduce a thermal simulation tool that was developed previously by the authors' group. The goal of the present study is to develop a numerical model by which to predict the temperature of a TiO{sub 2}-coated surface with a water film and integrate the calculation algorithm into the simulation tool. The availability of the proposed model was discussed in the present paper. Various urban districts in downtown Tokyo were selected for a discussion of the availability of the simulation tool in which the proposed model is integrated. Simulations were performed to quantify the thermal improvement effect of the cooling system in terms of surface temperature reduction, mean radiative temperature (MRT), heat island potential (HIP), indoor air temperature, and cooling load reduction. (author)

  4. MICROBIAL BIOFILMS PRODUCED BY PSEUDOMONAS FLUORESCENS ON SOLID SURFACES

    Directory of Open Access Journals (Sweden)

    Dagmar Kozelová

    2011-04-01

    Full Text Available Normal 0 21 false false false MicrosoftInternetExplorer4 Normal 0 21 false false false MicrosoftInternetExplorer4 A biofilm is a complex aggregation of microorganisms growing on a solid substrate. Biofilms are characterized by structural heterogeneity, genetic diversity, complex community interactions, and an extracellular matrix of polymeric substances. The experimental part was focused on the adhesion of bacterial cells under static conditions and testing the effectiveness of disinfectants on created biofilm. In laboratory conditions we prepared and formed the bacterial biofilms Pseudomonas fluorescens in the four test surfaces of stainless steel, glass and plastic materials - PE (polyethylene and EPDM (ethylene propylene diene monomer. Over the next 72 hours and 72 hours were observed numbers of adhesion bacterial cells of P. fluorescens on solid surfaces of tested materials. The highest values adhesion cells reached P. fluorescens cells after 72 hours of cultivation on plastic surfaces, where  was increased in adhesion bacterial cells for EPDM in the values of 105 CFU/cm2 and for PE up to 106 CFU/cm2. The subsequent repeated 72-hour cultivation P. fluorescens was an increase (growth in the number of adhesion bacterial cells to all tested surfaces.doi:10.5219/18  

  5. Progression towards optimization of viscosity of highly concentrated carbonaceous solid-water slurries by incorporating and modifying surface chemistry parameters with and without additives

    Science.gov (United States)

    Mukherjee, Amrita

    Carbonaceous solid-water slurries (CSWS) are concentrated suspensions of coal, petcoke bitumen, pitch etc. in water which are used as feedstock for gasifiers. The high solid loading (60-75 wt.%) in the slurry increases CSWS viscosity. For easier handling and pumping of these highly loaded mixtures, low viscosities are desirable. Depending on the nature of the carbonaceous solid, solids loading in the slurry and the particle size distribution, viscosity of a slurry can vary significantly. Ability to accurately predict the viscosity of a slurry will provide a better control over the design of slurry transport system and for viscosity optimization. The existing viscosity prediction models were originally developed for hard-sphere suspensions and therefore do not take into account surface chemistry. As a result, the viscosity predictions using these models for CSWS are not very accurate. Additives are commonly added to decrease viscosity of the CSWS by altering the surface chemistry. Since additives are specific to CSWS, selection of appropriate additives is crucial. The goal of this research was to aid in optimization of CSWS viscosity through improved prediction and selection of appropriate additive. To incorporate effect of surface chemistry in the models predicting suspension viscosity, the effect of the different interfacial interactions caused by different surface chemistries has to be accounted for. Slurries of five carbonaceous solids with varying O/C ratio (to represent different surface chemistry parameters) were used for the study. To determine the interparticle interactions of the carbonaceous solids in water, interfacial energies were calculated on the basis of surface chemistries, characterized by contact angles and zeta potential measurements. The carbonaceous solid particles in the slurries were assumed to be spherical. Polar interaction energy (hydrophobic/hydrophilic interaction energy), which was observed to be 5-6 orders of magnitude higher than the

  6. EUV: induced ablation and surface modifications of solids

    Science.gov (United States)

    Bartnik, A.; Fiedorowicz, H.; Jarocki, R.; Kostecki, J.; Szczurek, M.; Szczurek, A.; Wachulak, P.

    2011-06-01

    In this work results of investigations concerning ablation and surface modification of polymers and some other solids using a laser-plasma EUV source are presented. The plasma radiation was produced using a gas puff target and was focused with a gold-plated grazing incidence ellipsoidal collector. The ablation process was investigated using a scanning electron microscope (SEM) and a quadrupole mass spectrometer (QMS). The chemical changes were investigated by X-ray photoelectron spectroscopy (XPS). Different kinds of micro- and nanostructures created in nearsurface layers of the materials were obtained. Forms of the structures depend on a particular material and the EUV exposure. In case of some polymers even a single shot was sufficient for creation of the visible changes in surface morphology. In case of inorganic solids visible changes required usually the exposure with tens or hundreds of EUV pulses. XPS investigations revealed chemical changes in near surface layers of polymers. Significant differences were revealed in the XPS spectra acquired for irradiated and not-irradiated polymers. Significant decrease of functional groups containing oxygen was indicated. Analysis of QMS spectra indicate emission of different kinds of fragments of the polymer chains including the repeating structural units. In case of some polymers only fragments of the repeating unit were detected.

  7. 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

  8. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Improved surface hydrophilicity and antifouling property of polysulfone ultrafiltration membrane with poly(ethylene glycol) methyl ether methacrylate grafted graphene oxide nanofillers

    Science.gov (United States)

    Wang, Haidong; Lu, Xiaofei; Lu, Xinglin; Wang, Zhenghui; Ma, Jun; Wang, Panpan

    2017-12-01

    In this study, the GO-g-P(PEGMA) nanoplates were first synthesized by grafting hydrophilic poly (poly (ethylene glycol) methyl ether methacrylate) via surface-initiated atom transfer radical polymerization (SI-ATRP) method. A novel polysulfone (PSF) nanocomposite membrane using GO-g-P(PEGMA) nanoplates as nanofillers was fabricated. FTIR, TGA, 1H NMR, GPC and TEM were applied to verify the successful synthesis of the prepared nanoplates, while SEM, AFM, XPS, contact angle goniometry and filtration experiments were used to characterize the fabricated nanocomposite membranes. It was found that the new prepared nanofillers were well dispersed in organic PSF matrix, and the PSF/GO-g-P(PEGMA) nanocomposite membrane showed significant improvements in water flux and flux recovery rate. Based on the results of resistance-in-series model, the nanocomposite membrane exhibited superior resistance to the irreversible fouling. The excellent filtration and antifouling performance are attributed to the segregation of GO-g-P(PEMGA) nanofillers toward the membrane surface and the pore walls. Notably, the blended nanofillers appeared a stable retention in/on nanocomposite membrane after 30 days of washing time. The demonstrated method of synthesis GO-g-P(PEGMA) in this study can also be extended to preparation of other nanocomposite membrane in future.

  10. Homogenous Surface Nucleation of Solid Polar Stratospheric Cloud Particles

    Science.gov (United States)

    Tabazadeh, A.; Hamill, P.; Salcedo, D.; Gore, Warren J. (Technical Monitor)

    2002-01-01

    A general surface nucleation rate theory is presented for the homogeneous freezing of crystalline germs on the surfaces of aqueous particles. While nucleation rates in a standard classical homogeneous freezing rate theory scale with volume, the rates in a surface-based theory scale with surface area. The theory is used to convert volume-based information on laboratory freezing rates (in units of cu cm, seconds) of nitric acid trihydrate (NAT) and nitric acid dihydrate (NAD) aerosols into surface-based values (in units of sq cm, seconds). We show that a surface-based model is capable of reproducing measured nucleation rates of NAT and NAD aerosols from concentrated aqueous HNO3 solutions in the temperature range of 165 to 205 K. Laboratory measured nucleation rates are used to derive free energies for NAT and NAD germ formation in the stratosphere. NAD germ free energies range from about 23 to 26 kcal mole, allowing for fast and efficient homogeneous NAD particle production in the stratosphere. However, NAT germ formation energies are large (greater than 26 kcal mole) enough to prevent efficient NAT particle production in the stratosphere. We show that the atmospheric NAD particle production rates based on the surface rate theory are roughly 2 orders of magnitude larger than those obtained from a standard volume-based rate theory. Atmospheric volume and surface production of NAD particles will nearly cease in the stratosphere when denitrification in the air exceeds 40 and 78%, respectively. We show that a surface-based (volume-based) homogeneous freezing rate theory gives particle production rates, which are (not) consistent with both laboratory and atmospheric data on the nucleation of solid polar stratospheric cloud particles.

  11. Prediction of fluid velocity slip at solid surfaces

    DEFF Research Database (Denmark)

    Hansen, Jesper Schmidt; Todd, Billy; Daivis, Peter

    2011-01-01

    The observed flow enhancement in highly confining geometries is believed to be caused by fluid velocity slip at the solid wall surface. Here we present a simple and highly accurate method to predict this slip using equilibrium molecular dynamics. Unlike previous equilibrium molecular dynamics...... methods, it allows us to directly compute the intrinsic wall-fluid friction coefficient rather than an empirical friction coefficient that includes all sources of friction for planar shear flow. The slip length predicted by our method is in excellent agreement with the slip length obtained from direct...

  12. Friction and Wear Management Using Solvent Partitioning of Hydrophilic-Surface-Interactive Chemicals Contained in Boundary Layer-Targeted Emulsions

    Science.gov (United States)

    Richmond, Robert Chaffee (Inventor); Schramm, Jr., Harry F. (Inventor); Defalco, Francis G. (Inventor)

    2015-01-01

    Lubrication additives of the current invention require formation of emulsions in base lubricants, created with an aqueous salt solution plus a single-phase compound such that partitioning within the resulting emulsion provides thermodynamically targeted compounds for boundary layer organization thus establishing anti-friction and/or anti-wear. The single-phase compound is termed "boundary layer organizer", abbreviated BLO. These emulsion-contained compounds energetically favor association with tribologic surfaces in accord with the Second Law of Thermodynamics, and will organize boundary layers on those surfaces in ways specific to the chemistry of the salt and BLO additives. In this way friction modifications may be provided by BLOs targeted to boundary layers via emulsions within lubricating fluids, wherein those lubricating fluids may be water-based or oil-based.

  13. 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.

  14. Vibrational Action Spectroscopy of Solids: New Surface-Sensitive Technique

    Science.gov (United States)

    Wu, Zongfang; Płucienik, Agata; Feiten, Felix E.; Naschitzki, Matthias; Wachsmann, Walter; Gewinner, Sandy; Schöllkopf, Wieland; Staemmler, Volker; Kuhlenbeck, Helmut; Freund, Hans-Joachim

    2017-09-01

    Vibrational action spectroscopy employing infrared radiation from a free-electron laser has been successfully used for many years to study the vibrational and structural properties of gas phase aggregates. Despite the high sensitivity of this method no relevant studies have yet been conducted for solid sample surfaces. We have set up an experiment for the application of this method to such targets, using infrared light from the free-electron laser of the Fritz Haber Institute. In this Letter, we present first results of this technique with adsorbed argon and neon atoms as messengers. We were able to detect surface-located vibrations of a thin V2O3(0 0 0 1 ) film on Au(111) as well as adsorbate vibrations, demonstrating that this method is highly surface sensitive. We consider that the dominant channel for desorption of the messenger atoms is direct inharmonic vibrational coupling, which is essentially insensitive to subsurface or bulk vibrations. Another channel is thermal desorption due to sample heating by absorption of infrared light. The high surface sensitivity of the nonthermal channel and its insensitivity to subsurface modes makes this technique an ideal tool for the study of surface-located vibrations.

  15. The Adsorption of Gemini and Conventional Surfactants onto Some Soil Solids and the Removal of 2-Naphthol by the Soil Surfaces.

    Science.gov (United States)

    Rosen, M. J.; Li, Fang

    2001-02-15

    The adsorption of two cationic gemini surfactants, [C(n)H(2n+1) N(+)(CH(3))(2)-CH(2)CH(2)](2).2Br(-), where n=12 and 14, on limestone, sand, and clay (Na-montmorillonite) from their aqueous solution in double-distilled water and the effect of this adsorption on the removal of 2-naphthol have been studied. Compared to those of conventional cationic surfactants with similar single hydrophilic and hydrophobic groups (C(n)H(2n+1)N(+)(CH(3))(3).Br(-), where n=12 and 14), the molar adsorptions of the gemini and the conventional surfactants on Na-montmorillonite are almost identical and very close to their cation exchange capacities. On sand and limestone, the molar adsorption of the cationic gemini surfactants is much larger than that of their corresponding conventional surfactants. Adsorption studies of the pollutants onto the three kinds of solids treated by either the gemini or the conventional surfactants show that the former are both more efficient and more effective at removing 2-naphthol from the aqueous phase. On all three soil solids, the addition of KBr increases the efficiency of the adsorption of both types of cationics and for most cases increases also the maximum amount adsorbed, but decreases slightly the efficiency of removal of 2-naphthol. On limestone, the anionic gemini adsorbs with one hydrophilic group oriented toward the Ca(2+) sites on the surface and its second hydrophilic group oriented toward the aqueous phase. The conventional anionic surfactant forms a double layer. The gemini anionic is more efficient and more effective than the conventional anionic in the removal of 2-naphathol from the aqueous phase. Both anionic conventional and gemini surfactants have no adsorption on sand. The adsorption mechanisms for all the surfactants on the three soil solid surfaces are discussed. Copyright 2001 Academic Press.

  16. 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.

  17. Patterning Method for Silver Nanoparticle Electrodes in Fully Solution-Processed Organic Thin-Film Transistors Using Selectively Treated Hydrophilic and Hydrophobic Surfaces

    Science.gov (United States)

    Fukuda, Kenjiro; Takeda, Yasunori; Kobayashi, Yu; Shimizu, Masahiro; Sekine, Tomohito; Kumaki, Daisuke; Kurihara, Masato; Sakamoto, Masatomi; Tokito, Shizuo

    2013-05-01

    Fully solution-processed organic thin-film transistor (OTFT) devices have been fabricated with simple patterning process at a relatively low process temperature of 100 °C. In the patterning process, a hydrophobic amorphous fluoropolymer material, which was used as the gate dielectric layer and the underlying base layer, was treated with an oxygen plasma to selectively change its surface wetting properties from hydrophobic to hydrophilic. Silver source and drain electrodes were successfully formed in the treated areas with highly uniform line widths and without residues between the electrodes. Nonuniformities in the thickness of the silver electrodes originating from the “coffee-ring” effect were suppressed by optimizing the blend of solvents used with the silver nanoparticles, such that the printed electrodes are appropriate for bottom-gate OTFT devices. A fully solution-processed OTFT device using a polymer semiconductor material (PB16TTT) exhibited good electrical performance with no hysteresis in its transfer characteristics and with good linearity in its output characteristics. A relatively high carrier mobility of 0.14 cm2 V-1 s-1 and an on/off ratio of 1×105 were obtained with the fabricated TFT device.

  18. Response surface methodology based on central composite design accompanied by multivariate curve resolution to model gradient hydrophilic interaction liquid chromatography: Prediction of separation for five major opium alkaloids.

    Science.gov (United States)

    Taheri, Mohammadreza; Bagheri, Mohsen; Moazeni-Pourasil, Roudabeh Sadat; Ghassempour, Alireza

    2017-09-01

    Hydrophilic interaction liquid chromatography on bare silica presents some benefits for analysis and purification of ionizable basic alkaloids. This mode was used to separate five major opium alkaloids: morphine, codeine, thebaine, papaverine, and noscapine. Central composite design based on response surface methodology was applied for experimental design, modeling, and optimization in a single-step gradient method. The main effects and their interactions (initial percentage of modifier, changing range of modifier in run time, pH of buffer, and its concentration) were investigated in 30 experiments. Multivariate curve resolution-alternating least squares, by resolving overlapped curves, helped in the accurate calculation of baseline resolution factors to be modeled and optimized more accurately. Then three crucial resolution factors besides elution time were modeled in quadratic and cubic equations and optimized. In addition to the four factors, five extra logarithmic, and nonlogarithmic factors extracted from the four factors to give nine factors overall were inspected on mechanism of retention. It was shown that a linear combination consist of four independence variables successfully describes morphinans retentivity in a single-step gradient method. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Liquid Water may Stick on Hydrophobic Surfaces

    Indian Academy of Sciences (India)

    IAS Admin

    The behavior of fluid on a solid surface under static and dynamic conditions are usually clubbed together. • On a wetting surface (hydrophilic), liquid water is believed to adhere to the surface causing multilayer sticking. • On a non-wetting surface (hydrophobic), water is believed to glide across the surface leading to slip ...

  20. 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

  1. Probing and Mapping Electrode Surfaces in Solid Oxide Fuel Cells

    Science.gov (United States)

    Blinn, Kevin S.; Li, Xiaxi; Liu, Mingfei; Bottomley, Lawrence A.; Liu, Meilin

    2012-01-01

    Solid oxide fuel cells (SOFCs) are potentially the most efficient and cost-effective solution to utilization of a wide variety of fuels beyond hydrogen 1-7. The performance of SOFCs and the rates of many chemical and energy transformation processes in energy storage and conversion devices in general are limited primarily by charge and mass transfer along electrode surfaces and across interfaces. Unfortunately, the mechanistic understanding of these processes is still lacking, due largely to the difficulty of characterizing these processes under in situ conditions. This knowledge gap is a chief obstacle to SOFC commercialization. The development of tools for probing and mapping surface chemistries relevant to electrode reactions is vital to unraveling the mechanisms of surface processes and to achieving rational design of new electrode materials for more efficient energy storage and conversion2. Among the relatively few in situ surface analysis methods, Raman spectroscopy can be performed even with high temperatures and harsh atmospheres, making it ideal for characterizing chemical processes relevant to SOFC anode performance and degradation8-12. It can also be used alongside electrochemical measurements, potentially allowing direct correlation of electrochemistry to surface chemistry in an operating cell. Proper in situ Raman mapping measurements would be useful for pin-pointing important anode reaction mechanisms because of its sensitivity to the relevant species, including anode performance degradation through carbon deposition8, 10, 13, 14 ("coking") and sulfur poisoning11, 15 and the manner in which surface modifications stave off this degradation16. The current work demonstrates significant progress towards this capability. In addition, the family of scanning probe microscopy (SPM) techniques provides a special approach to interrogate the electrode surface with nanoscale resolution. Besides the surface topography that is routinely collected by AFM and STM

  2. Diffusion, Surface Kinetics, and Detection in Solid-State Nanopores

    Science.gov (United States)

    Hoogerheide, David; Garaj, Slaven; Golovchenko, Jene

    2010-03-01

    Solid-state nanopores are promising sensors for single biomolecules. Most sensing applications rely on electronic detection of changes in the ionic transport through or across the nanopore in the 0.1--10 kHz frequency band. Our recent studies of the electronic noise properties of silicon nitride nanopores highlight both the suitability of nanopores for physical measurements and their limits of detection (PRL 102, 256804 (2009)). We explore the dependence of excess white noise, which is dominant at detection frequencies, on electrolyte concentration, temperature, and pH. We detect two distinct processes: number fluctuations and surface charge fluctuations. Number fluctuations arise from carrier diffusion through the nanopore and represent a fundamental limit of voltage-driven detection techniques. This sort of noise is minimized at high electrolyte concentrations in low viscosity solutions. In addition, the interaction of ions in the solution with the surface produces fluctuations in the surface charge, and hence the conductance. This noise varies strongly with pH. Both are masked by 1/f noise at low frequencies. The usefulness of these noise sources for measuring physical constants such as diffusivity and reaction kinetics will be discussed.

  3. Stability of flocculated particles in concentrated and high hydrophilic solid layer-by-layer (LBL) emulsions formed using whey proteins and gum Arabic.

    Science.gov (United States)

    Lim, Aaron S L; Roos, Yrjö H

    2015-08-01

    The objective of the present study was to investigate flocculation in layer-by-layer (LBL) emulsion systems with high total solids content and deflocculation at various pH conditions, and the effects of whey protein isolate (WPI) concentration and total solids content on the stability of LBL emulsions. WPI (1.96% (1WPI) or 10.71% (10WPI), w/w in water) was prepared in water and high-pressure homogenized with sunflower oil (10%, w/w, of total emulsion). Gum Arabic (0.15%, w/w, in total emulsion) was added to assemble electrostatically on WPI at oil particle interfaces at pH3.5 using aqueous citric acid (10% w/w) forming LBL emulsion. The ζ-potential measurements showed charge reversal upon addition of gum Arabic solution into single layer (SL) emulsion confirming the formation of LBL interface. Trehalose:maltodextrin mixture (1:1, w/w, total emulsion, 28.57% (28) or 57.14% (57), w/w, in water) was used in the continuous phase. The high total solids content of the system results in depletion flocculation of the particles leading to bridging flocculation without coalescence as deflocculation into individual particles occurred with increasing pH from pH3.5 to pH6.5 in 10WPI systems. Deflocculation was evident in 10WPI-28 and 10WPI-57 as found from a decreased ζ-average diameter and visually under microscope. Coalescence was observed in 1WPI systems. Viscosity of the systems was significantly (P<0.05) increased with higher total solids content. Accelerated destabilization test showed that systems at higher WPI and total solids contents exhibited the highest stability against creaming. Deflocculation in LBL systems can be controlled by pH while high solids in the aqueous phase provide stability against creaming. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Chemical imaging and solid state analysis at compact surfaces using UV imaging

    DEFF Research Database (Denmark)

    Wu, Jian X.; Rehder, Sönke; van den Berg, Frans

    2014-01-01

    Fast non-destructive multi-wavelength UV imaging together with multivariate image analysis was utilized to visualize distribution of chemical components and their solid state form at compact surfaces. Amorphous and crystalline solid forms of the antidiabetic compound glibenclamide, and microcryst......Fast non-destructive multi-wavelength UV imaging together with multivariate image analysis was utilized to visualize distribution of chemical components and their solid state form at compact surfaces. Amorphous and crystalline solid forms of the antidiabetic compound glibenclamide...

  5. 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.

  6. Droplet impaction on solid surfaces exposed to impinging jet fires

    Energy Technology Data Exchange (ETDEWEB)

    Kazemi, Zia

    2005-12-15

    The thermal response of hot surfaces exposed to impinging jet fire and subsequent impacting water droplets is investigated. The research was done mainly experimentally by utilizing three different concepts. This included experiments on a laboratory scale steel plate and large outdoor fire tests with a quadratic steel channel and steel plates. Besides the horizontal jet flame itself was characterized in a comprehensive study. As a comparative study, the last three types of the experiment were additionally modeled by the CFD-code Kameleon FireEx for validation of results. The purpose of the experiments done on bench scale steel plate (L x W x T : 300 x 200 x 8 mm) was mainly to map data on wetting temperature, water droplet size, droplet impingement angle, and droplet velocity prior to large scale jet fire tests. The droplet release angle normal to hot surface gives best cooling effect, when the surface is oriented in upright position. The partial wetting begins at about 165 degrees C. When the surface is positioned in horizontal plane, the droplet of about 5 mm in diameter wets the hot surface partially at around 240-250 degrees C within an impaction distance of 20 cm. At about 150 degrees C, the droplet is entirely attached to the surface with almost zero contact angle, and cools down the solid at a critical heat flux equivalent to 1750 kW/m{sup 2}. The cooling effectiveness is about 8 % with a Weber number of 68. Although in the event of horizontal channel (L x W x T : 1000 x 200 x 8 mm) water droplets were not applied, however, the knowledge gained with jet fire tests gave valuable information about temperature progress in solids (steels and insulation) and their response to impinging jet fire during long duration experiments. The temperature of the insulated area of the channel keeps 200 degrees C below that of the exposed surface, as long as the insulation material remained intact. Upon long test fire durations, the insulation either burns or degrades despite

  7. 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.

  8. 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.

  9. Reflection of P and SV waves from free surface of an elastic solid ...

    Indian Academy of Sciences (India)

    The governing equations for generalized thermodiffusion in an elastic solid are solved. There exists three kinds of dilatational waves and a Shear Vertical (SV) wave in a two-dimensional model of the solid. The reflection phenomena of P and SV waves from free surface of an elastic solid with thermodiffusion is considered.

  10. PREFACE: International Conference on Solid Films and Surfaces (ICSFS 2014)

    Science.gov (United States)

    Achete, C. A.; Almeida, C. M.; Cremona, M.; Rocca, M.; Stavale, F.

    2015-03-01

    Foreword The 17th ICSFS took place at the wonderful city of Rio de Janeiro, Brazil from the 8th to the 11th of September, 2014. The conference focused on recent advances in controlling and characterizing the physical and chemical properties of films and surfaces, with a particular emphasis on materials for electronic, photonic and spintronic applications. In addition, themes of bio-functionalized structures and devices were strongly discussed in the ICSFS, covering interdisciplinary nano and nano-bio science and technology. The conference has promoted, in various sub-fields of materials surfaces and thin films, an excellent forum for exchange of ideas, presentation of technical achievements and discussion of future directions in the field. In this volume of the IOP Conference Series: Materials Science and Engineering we are glad to present 11 peer-reviewed ICSFS contributing papers. The cross-disciplinary nature of conference topics is clearly reflected in these Proceedings' contents. The themes discussed ranged from those close to more traditional condensed matter physics, such as semiconductor surfaces to physical chemistry related issues. The Proceedings were organized in accordance with contributions presented at the Conference. We were glad with the presence of over 160 participants, including 24 invited and plenary talks and over 50 oral contributions. We strongly believe that these Proceedings will be useful for a wide audience of those interested in basic and applied surfaces and thin solid interfaces. Acknowledgment We would like to acknowledge the hard work, professional skills and efficiency of the team which oversaw the general organization, particularly of Dicom (Social Communication Division) from the National Institute of Metrology, Quality and Technology, Inmetro (Brazil). We also would like to thank all the invited speakers and session chairs for making the meeting such a great success. The Conference was supported and sponsored by Academia

  11. A mean field approach for computing solid-liquid surface tension for nanoscale interfaces

    Science.gov (United States)

    Chiu, Chi-cheng; Ranatunga, R. J. K. Udayana; Flores, David Torres; Pérez, D. Vladimir; Moore, Preston B.; Shinoda, Wataru; Nielsen, Steven O.

    2010-02-01

    The physical properties of a liquid in contact with a solid are largely determined by the solid-liquid surface tension. This is especially true for nanoscale systems with high surface area to volume ratios. While experimental techniques can only measure surface tension indirectly for nanoscale systems, computer simulations offer the possibility of a direct evaluation of solid-liquid surface tension although reliable methods are still under development. Here we show that using a mean field approach yields great physical insight into the calculation of surface tension and into the precise relationship between surface tension and excess solvation free energy per unit surface area for nanoscale interfaces. Previous simulation studies of nanoscale interfaces measure either excess solvation free energy or surface tension, but these two quantities are only equal for macroscopic interfaces. We model the solid as a continuum of uniform density in analogy to Hamaker's treatment of colloidal particles. As a result, the Hamiltonian of the system is imbued with parametric dependence on the size of the solid object through the integration limits for the solid-liquid interaction energy. Since the solid-liquid surface area is a function of the size of the solid, and the surface tension is the derivative of the system free energy with respect to this surface area, we obtain a simple expression for the surface tension of an interface of arbitrary shape. We illustrate our method by modeling a thin nanoribbon and a solid spherical nanoparticle. Although the calculation of solid-liquid surface tension is a demanding task, the method presented herein offers new insight into the problem, and may prove useful in opening new avenues of investigation.

  12. Initial adhesion of Listeria monocytogenes to solid surfaces under liquid flow

    DEFF Research Database (Denmark)

    Szlavik, Julie; Soares Paiva, Dionísio; Mørk, Nils

    2012-01-01

    strains of L. monocytogenes was investigated under liquid flow at two levels of shear stress on six different surfaces using a flow chamber set-up with microscopy measurements. The surfaces tested were glass and PVC, and glass coated with beef extract, casein, and homogenised and unhomogenised milk......, there was a significant effect of the surfaces tested (pflow rate (shear stress) as seen by a decrease in adhesion at high shear stress for most strains. A significant effect of interactions between strain-surface and strain-shear stress (p... using Microbial Adhesion To Solvents (MATS). All surfaces with the exception of PVC were found to be hydrophilic. Strain differences were found to significantly influence the initial adhesion rate (IAR) of all nine strains to all the surfaces (p

  13. Thermal boundary conductance of hydrophilic and hydrophobic ionic liquids

    Science.gov (United States)

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

    2015-03-01

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

  14. Physics of foam formation on a solid surface in carbonated liquids

    NARCIS (Netherlands)

    Zuidberg, A.F.

    1997-01-01

    The amount and size of bubbles in a foam layer that have originated from a solid surface in a gas supersaturated solution is largely determined by the physical properties of that solid and liquid surface and the supersaturation level of the gas in the liquid. The presence of pre-existent

  15. Condensation Enhancement by Surface Porosity: Three-Stage Mechanism.

    Science.gov (United States)

    Yarom, Michal; Marmur, Abraham

    2015-08-18

    Surface defects, such as pores, cracks, and scratches, are naturally occurring and commonly found on solid surfaces. However, the mechanism by which such imperfections promote condensation has not been fully explored. In the current paper we thermodynamically analyze the ability of surface porosity to enhance condensation on a hydrophilic solid. We show that the presence of a surface-embedded pore brings about three distinct stages of condensation. The first is capillary condensation inside the pore until it is full. This provides an ideal hydrophilic surface for continuing the condensation. As a result, spontaneous condensation and wetting can be achieved at lower vapor pressure than on a smooth surface.

  16. Tribology of thin wetting films between bubble and moving solid surface.

    Science.gov (United States)

    Karakashev, Stoyan I; Stöckelhuber, Klaus W; Tsekov, Roumen; Phan, Chi M; Heinrich, Gert

    2014-08-01

    This work shows a successful example of coupling of theory and experiment to study the tribology of bubble rubbing on solid surface. Such kind of investigation is reported for the first time in the literature. A theory about wetting film intercalated between bubble and moving solid surface was developed, thus deriving the non-linear evolution differential equation which accounted for the friction slip coefficient at the solid surface. The stationary 3D film thickness profile, which appears to be a solution of the differential equation, for each particular speed of motion of the solid surface was derived by means of special procedure and unique interferometric experimental setup. This allowed us to determine the 3D map of the lift pressure within the wetting film, the friction force per unit area and the friction coefficient of rubbing at different speeds of motion of the solid surface. Thus, we observed interesting tribological details about the rubbing of the bubble on the solid surface like for example: 1. A regime of mixed friction between dry and lubricated friction exists in the range of 6-170 μm/s, beyond which the rubbing between the bubble and solid becomes completely lubricated and passes through the maximum; 2. The friction coefficient of rubbing has high values at very small speeds of solid's motion and reduces substantially with the increase of the speed of the solid motion until reaching small values, which change insignificantly with the further increase of the speed of the solid. Despite the numerous studies on the motion of bubble/droplet in close proximity to solid wall in the literature, the present investigation appears to be a step ahead in this area as far as we were able to derive 3D maps of the bubble close to the solid surface, which makes the investigation more profound. © 2013.

  17. Friction surface cladding: development of a solid state cladding process

    NARCIS (Netherlands)

    van der Stelt, A.A.

    2014-01-01

    Many industries including automotive, aerospace, electronics, shipbuilding, offshore, railway and heavy equipment employ surface modification technologies to change the surface properties of a manufactured product. Often, the surface is covered (coated) with a dissimilar clad layer for this purpose

  18. Adsorption and nanowear properties of bovine submaxillary mucin films on solid surfaces: Influence of solution pH and substrate hydrophobicity

    DEFF Research Database (Denmark)

    Sotres, Javier; Madsen, Jan Busk; Arnebrant, Thomas

    2014-01-01

    The adsorption and mechanical stability of bovine submaxillary mucins (BSM) films at solid-liquid interfaces were studied with respect to both substrate hydrophobicity and solution pH. Dynamic light scattering revealed a single peak distribution in neutral aqueous solution (pH 7.4) and a small...... fraction with enhanced aggregation was observed in acidic solution (pH 3.8). Both substrate hydrophobicity and solution pH were found to affect the spontaneous adsorption of BSM onto solid surfaces; BSM adsorbed more onto hydrophobic surfaces than hydrophilic ones, and adsorbed more at pH 3.8 than at pH 7.......4. Thus, the highest "dry" adsorbed mass was observed for hydrophobic surfaces in pH 3.8 solution. However, a highest "wet" adsorbed mass, i.e. which includes the solvent coupled to the film, was observed for hydrophobic surfaces at pH 7.4. The mechanical stability of the films was studied...

  19. 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...

  20. Molecular Dynamics calculation of solid/liquid surface tension: a methodological study

    Science.gov (United States)

    Pineau, Nicolas; Dreher, Thibaud; Soulard, Laurent; Bourasseau, Emeric; Malfreyt, Patrice

    2017-06-01

    The influence of polymer/molecular crystal interfaces on the mechanical properties of Polymer Binded Explosives under high strains is an open topic which can be explored through surface tension calculations. While such calculations are being performed for liquid/liquid and liquid/vapor interfaces intensively, little is known for the solid/liquid and solid/solid interfaces. The aim of this work is to fill that gap by computing the solid/liquid surface tension of a simple model system consisting of a graphene sheet embedded in liquid methane. We show that, unlike the liquid/vapour and liquid/liquid systems, the presence of a solid substrate has a strong impact on the structure of the fluid phase and that the simulation parameters should be chosen carefully to compute accurate surface tensions.

  1. Detection of hazelnut oil in extra-virgin olive oil by analysis of polar components by micro-solid phase extraction based on hydrophilic liquid chromatography and MALDI-ToF mass spectrometry.

    Science.gov (United States)

    Calvano, Cosima D; Aresta, Antonella; Zambonin, Carlo G

    2010-09-01

    The oil polar fraction may have a great potential for the characterization of vegetable oils and for the individuation of adulterations. In particular, adulteration of extra-virgin olive oil (EVOO) with hazelnut oil (HO) is one of the most difficult ones to detect due to the similar composition as regards triacylglycerol, total sterol and fatty acid profile. A new micro-solid phase extraction (µ-SPE) procedure based on hydrophilic liquid chromatography (HILIC) micro-columns was developed for the selective extraction and enrichment of polar compounds from EVOO and HO before matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-ToF-MS) analysis. The method permits a simple and fast qualitative analysis of the polar fraction of the oils under study; furthermore, some peaks (such as the m/z ions 496.39, 520.46 and 522.47) were found to be present only in HO, indicating that they could be diagnostic for the presence of HO in EVOO. In order to verify the potential of the method for the individuation of this adulteration, EVOO was progressively adulterated with variable quantities of HO, subjected to the HILIC enrichment and finally to MALDI-ToF-MS analysis; the detection of adulteration was possible up to the level of 5%. Eventually, diagnostic polar compounds were identified as lysophosphatidylcholine (LPC) (16:0/0:0), LPC (18:2/0:0), LPC (18:1/0:0) by means of capillary liquid chromatography-electrospray ionization-quadrupole-ToF-MS (CapLC-ESI-Q-ToF-MS) analysis. 2010 John Wiley & Sons, Ltd.

  2. Modelling Gas Adsorption in Porous Solids: Roles of Surface ...

    Indian Academy of Sciences (India)

    Modelling the adsorption of small molecule gases such as N2 , CH4 and CO2 in porous solids can provide valuable insights for the development of next generation materials. Employing a grand canonical Monte Carlo simulation code developed in our group, the adsorption isotherms of CH4 and CO2 in many metal organic ...

  3. Modelling Gas Adsorption in Porous Solids: Roles of Surface ...

    Indian Academy of Sciences (India)

    Abstract. Modelling the adsorption of small molecule gases such as N2, CH4 and CO2 in porous solids can provide valuable insights for the development of next generation materials. Employing a grand canonical Monte. Carlo simulation code developed in our group, the adsorption isotherms of CH4 and CO2 in many ...

  4. 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.

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

    NARCIS (Netherlands)

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

    2016-01-01

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

  6. Reprogrammable Assembly of Molecular Motor on Solid Surfaces via Dynamic Bonds.

    Science.gov (United States)

    Yu, Li; Sun, Jian; Wang, Qian; Guan, Yan; Zhou, Le; Zhang, Jingxuan; Zhang, Lanying; Yang, Huai

    2017-06-01

    Controllable assembly of molecular motors on solid surfaces is a fundamental issue for providing them to perform physical tasks. However, it can hardly be achieved by most previous methods due to their inherent limitations. Here, a general strategy is designed for the reprogrammable assembly of molecular motors on solid surfaces based on dynamic bonds. In this method, molecular motors with disulfide bonds can be remotely, reversibly, and precisely attached to solid surfaces with disulfide bonds, regardless of their chemical composition and microstructure. More importantly, it not only allows encoding geometric information referring to a pattern of molecular motors, but also enables erasing and re-encoding of geometric information via hemolytic photocleavage and recombination of disulfide bonds. Thus, solid surfaces can be regarded as "computer hardware", where molecular motors can be reformatted and reprogramed as geometric information. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. 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.

  8. A comparative study of the effectiveness of early and delayed loading of short tissue-level dental implants with hydrophilic surfaces placed in the posterior section of the mandible-A preliminary study.

    Science.gov (United States)

    Makowiecki, Arkadiusz; Botzenhart, Ute; Seeliger, Julia; Heinemann, Friedhelm; Biocev, Peter; Dominiak, Marzena

    2017-07-01

    The objective of the present study was to compare the primary and secondary stability of tissue-level short dental titanium implants with polished necks and hydrophilic surfaces of two different designs and manufacturers. The first implant system used (SPI ® ELEMENT RC INICELL titanium implants, Thommen Medical AG, Grenchen, Switzerland), allowed functional loading 6 weeks after its placement, whereas the second implant system (RN SLActiv ® tissue-level titanium implants, Straumann GmbH, Fribourg, Germany), was loaded after 15 weeks. The degree of primary and secondary stability was determined using an Osstell ISQ measuring device. Marginal bone loss (MBL) was evaluated radiographically 12 and 24 weeks after implantation and the Wachtel's healing index as well as the patient's satisfaction with the treatment was registered on a VAS scale. The intergroup comparison revealed significant differences in terms of primary stability as well as differences in MBL 3 months after the procedure, but no significant differences could be found after 6 months and for secondary stability. The primary stability was significantly higher for Thommen ® compared to Straumann ® implants. Insertion of short dental implants with a hydrophilic conditioned surface significantly shortens patient treatment time. Copyright © 2017 Elsevier GmbH. All rights reserved.

  9. 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 detail results were obtained only under dry

  10. Surface energies of metals in both liquid and solid states

    Energy Technology Data Exchange (ETDEWEB)

    Aqra, Fathi, E-mail: fathiaqra2009@hotmail.com [Department of Chemistry, Faculty of Science and Technology, Hebron University, P.O. Box 40, Hebron, West Bank, Palestine (Country Unknown); Ayyad, Ahmed [Department of Chemistry, Faculty of Science and Technology, Hebron University, P.O. Box 40, Hebron, West Bank, Palestine (Country Unknown)

    2011-05-15

    Although during the last years one has seen a number of systematic studies of the surface energies of metals, the aim and the scientific meaning of this research is to establish a simple and a straightforward theoretical model to calculate accurately the mechanical and the thermodynamic properties of metal surfaces due to their important application in materials processes and in the understanding of a wide range of surface phenomena. Through extensive theoretical calculations of the surface tension of most of the liquid metals, we found that the fraction of broken bonds in liquid metals (f) is constant which is equal to 0.287. Using our estimated f value, the surface tension ({gamma}{sub m}), surface energy ({gamma}{sub SV}), surface excess entropy (-d{gamma}/dT), surface excess enthalpy (H{sub s}), coefficient of thermal expansion ({alpha}{sub m} and {alpha}{sub b}), sound velocity (c{sub m}) and its temperature coefficient (-dc/dT) have been calculated for more than sixty metals. The results of the calculated quantities agree well with available experimental data.

  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

    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.

  12. Catalyst characterization science: surface and solid state chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Deviney, M.L.; Gland, J.L. (eds.)

    1985-01-01

    The large number of typescript papers in this volume derive from a symposium held at the ACS meeting in Philadelphia in 1984. They are grouped in these categories: Spectral Surface Techniques on Complex Catalyst Systems; Multiple Surface Techniques on Model Catalyst Systems; Catalytic Mechanisms on Well-Defined Surfaces; Characterization of Bimetallic Catalysts; New Perspectives in Catalysis via Electron Microscopy and X-ray Scattering; Vibrational Characterization of Catalytic Reactions; Magnetic Methods in Catalyst Research; and New Techniques in Electrocatalysis. Both an author and a subject index are included.

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

    Science.gov (United States)

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

    2015-05-20

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

  14. Revisiting lowest possible surface energy of a solid

    Science.gov (United States)

    Chen, Zhou; Nosonovsky, Michael

    2017-12-01

    The solid–vapor surface energy cannot be determined directly from the contact angle data because the Young equation includes three unknown interfacial energies. While the liquid–vapor energy is usually known, different theories can be used to exclude the solid–liquid energy, such as Antonoff, Zisman, Fowkes, and Owens and Wendt theories. These theories yield significantly different results for the solid–vapor surface energy. We revisit the claim that the lowest surface energy is 6.7 mJ m‑2 of C20F42, while polytetrafluoroethylene’s surface energy is 22 mJ m‑2. These numbers can change significantly if a different theory is used.

  15. Photoelectron spectroscopy and Auger electron spectroscopy of solids and surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kowalczyk, S.P.

    1976-01-01

    The use of photoelectron spectroscopy, primarily x-ray photoelectron spectroscopy, to obtain information on the electronic structure of a wide variety of solids (especially the bulk electronic structure of solids) is covered. Both valence band and core-level spectra, as well as a few cases of photon excited Auger electron spectroscopy, are employed in the investigations to derive information on N(E). The effect of several modulations inherent in the measured I(E)'s, such as final state band structure, cross section, and relaxation, is discussed. Examples of many-electron interactions in PES are given. Some experimental aspects of PES and AES studies are given with emphasis on sample preparation techniques. Multiple splitting of core levels is examined using the Mn levels in MnF/sub 2/ as a detailed case study. Core level splittings in transition metals, rare earth metals, transition metal halides and several alloys are also reported. The application of PES to the study of the chemical bond in some crystalline semiconductors and insulators, A/sup N/B/sup 8-N/ and A/sup N/B/sup 10-N/ compounds is treated, and a spectroscopic scale of ionicity for these compounds is developed from the measured ''s-band'' splitting in the valence band density of states. (GHT)

  16. Effect of surface structure on lubrication in water of hydrophilic/hydrophobic block copolymer coating membrane; Shinsuisei/sosuisei block kyojugotai coating maku no hyomen kozo to suichu deno junkatsu tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Aoike, T.; Shimura, K.; Onishi, M. [Terumo Corp., Tokyo (Japan); Hironaka, S. [Tokyo Institute of Technology, Tokyo (Japan)

    1998-07-01

    A polyurethane substrate is coated with a hydrophilic/hydrophobic block copolymer [poly(N,Nprime-dimethylacrylamide)-block-poly (glycidylmethacrylate), PDMAA-b-PGMA] by the solvent casting method, and dried at 80 to 140degC, to investigate the surface structures and lubrication in water. The hydrophilic PGMA segment is concentrated in the uppermost layer of the coating film, before it is brought into contact with water, and this is more noted as drying temperature increases. The uppermost layer dried at low temperature (80 and 100degC) undergoes a structural change, when immersed in water, from the PGMA segment-rich to PDMAA segment-rich condition, showing a dynamic friction coefficient of 0.03 to 0.04. Lubrication of the sample in water tends to decrease as drying temperature increases, which results from different degree of the structural change in water, depending on degree of concentration of the PGMA segment in the uppermost layer. 10 refs., 11 figs., 1 tab.

  17. Non-equilibrium dynamics of single polymer adsorption to solid surfaces

    NARCIS (Netherlands)

    Panja, D.|info:eu-repo/dai/nl/370992105; Barkema, G.T.|info:eu-repo/dai/nl/101275080; Kolomeisky, A.B.

    2009-01-01

    The adsorption of polymers to surfaces is crucial for understanding many fundamental processes in nature. Recent experimental studies indicate that the adsorption dynamics is dominated by non-equilibrium effects. We investigate the adsorption of a single polymer of length N to a planar solid surface

  18. Pulsed surface flashover across solid insulators in vacuum

    Science.gov (United States)

    Ko, S. T.; Lakdawala, V. K.

    1985-01-01

    The phenomenon of pulsed surface flashover is studied using a fast image converter camera. A still photograph of a surface flashover for a TiO2 test piece reveals that the breakdown path is a straight line perpendicular to the streak direction. It is found that visible light is initially emitted from the cathode and that the light front propagates at a constant speed of about 1 x 10 to the 7th m/s. The low luminous light is emitted up to the point where the gap is bridged by the bright light.

  19. Adsorption of polylysines at solid-liquid interfaces

    NARCIS (Netherlands)

    Bonekamp, B.C.

    1984-01-01

    Adsorption properties of the polyelectrolytes poly-L-lysine (PL-L) and poly-DL-lysine (PL-DL) on hydrophobic (polystyrene latex, silver iodide) and hydrophilic (silica) negatively charged solid particles were studied.
    Adsorbed amounts as a function of concentration, ionic strength, surface

  20. Metal halide solid-state surface treatment for nanocrystal materials

    Energy Technology Data Exchange (ETDEWEB)

    Luther, Joseph M.; Crisp, Ryan; Beard, Matthew C.

    2016-04-26

    Methods of treating nanocrystal and/or quantum dot devices are described. The methods include contacting the nanocrystals and/or quantum dots with a solution including metal ions and halogen ions, such that the solution displaces native ligands present on the surface of the nanocrystals and/or quantum dots via ligand exchange.

  1. Modifying zirconia solid electrolyte surface property to enhance oxide transport

    Energy Technology Data Exchange (ETDEWEB)

    Liaw, B.Y.; Song, S.Y. [Univ. of Hawaii, Honolulu, HI (United States)

    1996-12-31

    Bismuth-strontium-calcium-copper oxide (Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, BSCCO) is known for its high T{sub c} superconducting behavior and mixed conducting property. The applicability of similar high T{sub c} cuprates for intermediate-temperature solid oxide fuel cell (SOFC) application has been studied recently. We investigated the electrochemical behavior of several Ag{vert_bar}BSCCO{vert_bar}10 mol% yttria-stabilized zirconia (YSZ){vert_bar}Ag and Ag{vert_bar}YSZ{vert_bar}Ag cells using complex impedance spectroscopy. A highly uniform and porous microstructure was observed at the interface of the YSZ and BSCCO. The ionic conductivity determined from the Nyquest plots in the temperature range of 200-700{degrees}C agrees with the values reported in the literature. The specific resistance of the BSCCO{vert_bar}YSZ interface was also determined to be lower than those of the conventional manganite electrode, suggesting that BSCCO seems attractive for cathode applications in SOFC.

  2. Adsorption of the Three-phase Emulsion on Various Solid Surfaces.

    Science.gov (United States)

    Enomoto, Yasutaka; Imai, Yoko; Tajima, Kazuo

    2017-07-01

    The present study investigates the adsorption of the three-phase emulsion on various solid/water interfaces. Vesicles can be used as emulsifiers in the three-phase emulsions and act as an independent phase unlike the surfactant used in conventional emulsions; therefore, it is expected that the three-phase emulsion formed by the adhesion of vesicles to the oil/water interface will adsorb on various solid/water interfaces. The cationic three-phase emulsion was prepared to encourage emulsion adsorption on negatively charged solid substrates in water. The emulsifier polyoxyethylene-(10) hydrogenated castor oil was rendered cationic by mixing with the surfactant cetyltrimethylammonium bromide and then used to prepare the cationic three-phase emulsion of hexadecane-in-water. Three solid substrates (silicon, glass, and copper) were dipped in the cationic emulsion and the emulsion was found to adsorb on the solid substrates while maintaining its structure. The amount of hexadecane adsorbed on the various surfaces was investigated by gas chromatography and found to increase with increasing hexadecane concentration in the emulsion and eventually plateaued just like molecular adsorption. The maximum surface coverage of the emulsion on the substrates was approximately 80%. However, even the equivalent nonionic three-phase emulsion was found to adsorb on the three solid surfaces. This was attributed to a novel mechanism of irreversible adhesion via the van der Waals attractive force.

  3. Surface-generated ultrasonic waves in solids by a Nd-YAG laser

    Science.gov (United States)

    Emmony, David C.; Ward, Barry

    1993-01-01

    A Q switched Nd-YAG laser has been used to generate ultrasonic waves at air-solid boundaries. The high energy and power density at the laser focus leads to the formation of a plasma on the surface of the solid. The solid surface is heated to the vaporization point and the combined effects of the laser plasma and surface ablation lead to shock waves in the air and a high pressure transient acoustic wave in the solid. This laser generated ultrasound is being used to study material properties and is used in non-destructive testing. Laser ultrasound has been studied using a range of transducers to confirm the thermoelastic and ablation regimes. But in general these techniques do not give the spatial as well as temporal behavior of the waves. Schlieren photography using a dye laser has been used to study the propagation of the various wave types at an air-solid boundary and Mach Zehnder interferometry has been used to determine the absolute pressure in transparent solids. The pressure has been measured as a function of time and the radial dependence is in excellent agreement with the direct pressure transducer measurements of other workers in the ablation regime.

  4. The dynamic spreading of nanofluids on solid surfaces - Role of the nanofilm structural disjoining pressure.

    Science.gov (United States)

    Lim, Sangwook; Zhang, Hua; Wu, Pingkeng; Nikolov, Alex; Wasan, Darsh

    2016-05-15

    Nanofluids comprising nanoparticle suspensions in liquids have significant industrial applications. Prior work performed in our laboratory on the spreading of an aqueous film containing nanoparticles displacing an oil droplet has clearly revealed that the structural disjoining pressure arises due to the layering of the nanoparticles normal to the confining plane of the film with the wedge profile. The pressure drives the nanofluid in the wedge film and the nanofluid spreads. We observed two distinct contact lines: the inner contact line, where the structural disjoining pressure dominates the Laplace capillary pressure, and the outer contact line, given by the Laplace equation prediction extrapolated to the solid substrate where the structural disjoining pressure contribution is negligible. We report here our results of the effects of several parameters, such as the nanoparticle concentration, liquid salinity, temperature, and the substrate contact angle, on the motion of the two contact lines and their effects on the detachment of the oil droplet. We also studied the equilibrated and non-equilibrated oil/nanofluid phases, the time of adhesion of the oil droplet on the solid substrate and the drying time of the substrate. We employed the frictional model to predict the outer contact line velocity and our previous theoretical model (based on the structural disjoining pressure) to predict the inner contact line velocity. The theoretical predictions agreed quite well with the experimentally measured values of the velocities. Our experimental results showed that the motion of the inner contact line was accelerated by the increase in the nanoparticle concentration, temperature, and hydrophilicity of the substrate for the pre-equilibrated oil/nanofluid phases, which resulted in the faster detachment of the oil droplet. The speed of the two contact lines decreased upon the increase in the drying time of the substrate and the oil adhesion time on the substrate. The present

  5. Projectile charge state dependent sputtering of solid surfaces

    CERN Document Server

    Hayderer, G

    2000-01-01

    dependence on the ion kinetic energy. This new type of potential sputtering not only requires electronic excitation of the target material, but also the formation of a collision cascade within the target in order to initiate the sputtering process and has therefore been termed kinetically assisted potential sputtering. In order to study defects induced by potential sputtering on the atomic scale we performed measurements of multiply charged Ar ion irradiated HOPG (highly oriented pyrolitic graphite) samples with scanning tunneling microscopy (STM). The only surface defects found in the STM images are protrusions. The mean diameter of the defects increases with projectile charge state while the height of the protrusions stays roughly the same indicating a possible pre-equilibrium effect of the stopping of slow multiply charged projectiles in HOPG. Total sputter yields for impact of slow singly and multiply charged ions on metal- (Au), oxide- (Al2O3, MgO) and alkali-halide surfaces (LiF) have been measured as a...

  6. 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Hydrophilic PEO-PDMS for microfluidic applications

    Science.gov (United States)

    Yao, Mingjin; Fang, Ji

    2012-02-01

    Polydimethylsiloxane (PDMS) is a popularly used nontoxic and biocompatible material in microfluidic systems, which is relatively cheap and does not break easily like glass. The simple fabrication, optical transparency and elastomeric property make PDMS a handy material to work with. In order to develop different applications of PDMS in microfluidics and bioengineering, it is necessary to modify the PDMS surface nature to improve wetting characteristics, and to have a better control in nonspecific binding of proteins and cells, as well as to increase adhesion. At the moment, the hydrophilic surface modification performance of PDMS is known to recover its hydrophobicity shortly after oxidation modification, which is not stable in the long term (Owen and Smith 1994 J. Adhes. Sci. Technol. 8 1063-75). This paper presents a long-term stable hydrophilic surface modification processing of PDMS. The poly(dimethylsiloxane-ethylene oxide polymeric) (PDMS-b-PEO) is used in this project as a surfactant additive to be added into the PDMS base and the curing agent mixture during polymerization and to create hydrophilic PEO-PDMS. The contact angle can be controlled at 21.5-80.9° with the different mixing ratios and the hydrophilicity will remain stable for two months and then slightly varied later. We also investigate the bonding conditions of the modified PDMS to a silicon wafer and a glass wafer. To demonstrate its applications, we designed a device which consists of microchannels on a silicon wafer, and PEO-PDMS is utilized as a cover sheet. The capillary function was investigated under the different contact angles of PED-PDMS and with different aspect ratios of microchannels. All of the processes and testing data are presented in detail. This easy and cost-effective modified PDMS with a good bonding property can be widely used in the capillary device and systems, and microfluidic devices for fluid flow control of the microchannels in biological, chemical, medical

  8. Covalent attachment of proteins to solid supports and surfaces via Sortase-mediated ligation.

    Directory of Open Access Journals (Sweden)

    Lilyan Chan

    Full Text Available BACKGROUND: There is growing interest in the attachment of proteins to solid supports for the development of supported catalysts, affinity matrices, and micro devices as well as for the development of planar and bead based protein arrays for multiplexed assays of protein concentration, interactions, and activity. A critical requirement for these applications is the generation of a stable linkage between the solid support and the immobilized, but still functional, protein. METHODOLOGY: Solid supports including crosslinked polymer beads, beaded agarose, and planar glass surfaces, were modified to present an oligoglycine motif to solution. A range of proteins were ligated to the various surfaces using the Sortase A enzyme of S. aureus. Reactions were carried out in aqueous buffer conditions at room temperature for times between one and twelve hours. CONCLUSIONS: The Sortase A transpeptidase of S. aureus provides a general, robust, and gentle approach to the selective covalent immobilization of proteins on three very different solid supports. The proteins remain functional and accessible to solution. Sortase mediated ligation is therefore a straightforward methodology for the preparation of solid supported enzymes and bead based assays, as well as the modification of planar surfaces for microanalytical devices and protein arrays.

  9. Calculation of a solid/liquid surface tension: A methodological study

    Science.gov (United States)

    Dreher, T.; Lemarchand, C.; Soulard, L.; Bourasseau, E.; Malfreyt, P.; Pineau, N.

    2018-01-01

    The surface tension of a model solid/liquid interface constituted of a graphene sheet surrounded by liquid methane has been computed using molecular dynamics in the Kirkwood-Buff formalism. We show that contrary to the fluid/fluid case, the solid/liquid case can lead to different structurations of the first fluid layer, leading to significantly different values of surface tension. Therefore we present a statistical approach that consists in running a series of molecular simulations of similar systems with different initial conditions, leading to a distribution of surface tensions from which an average value and uncertainty can be extracted. Our results suggest that these distributions converge as the system size increases. Besides we show that surface tension is not particularly sensitive to the choice of the potential energy cutoff and that long-range corrections can be neglected contrary to what we observed in the liquid/vapour interfaces. We have not observed the previously reported commensurability effect.

  10. Highly ordered nanoscale patterns produced by masked ion bombardment of a moving solid surface

    Science.gov (United States)

    Gelfand, Martin P.; Bradley, R. Mark

    2012-09-01

    We introduce a fabrication method in which a mask with a long, narrow slit is placed between the source of an ion beam and the surface of a solid moving with constant speed. Numerical simulations reveal the method can generate surface ripples and arrays of nanoholes that are virtually defect free. In contrast, the patterns produced by ion bombardment with a broad, unmasked beam are typically rife with defects.

  11. Interactions between solid surfaces mediated by polyethylene oxide polymers: effect of polymer concentration.

    Science.gov (United States)

    Wei, Xiaoling; Gong, Xiangjun; Ngai, To

    2013-09-03

    Using total internal reflection microscopy (TIRM), we have systematically measured the interactions between a microsphere and a flat hydrophilic surface in the presence of polyethylene oxide (PEO) polymer solution. Our results reveal that PEO significantly mediates the interaction forces between the two surfaces. At low polymer concentration, the interactions between two surfaces in the presence of PEO are mainly dominated by repulsive forces, originating from diffuse layer overlap. At intermediate polymer concentration, a long-range and weak attraction sets in. This force is likely attributed to the depletion attraction due to the presence of free PEO chains in bulk solution; however, a simple hard-sphere AO model fails to precisely describe the attraction. At high polymer concentration where PEO chains overlap, the attraction disappears, and levitation of the microsphere probe is detected. We argue that at this overlapping region, the correlation length of PEO chains is much smaller than the size of single PEO molecule, leading to weakening and disappearing of the depletion attraction. Finally, at very high concentration, oscillatory structural force is obviously found, indicating the significant structural ordering of the PEO chains under confinement.

  12. Free surface modeling of contacting solid metal flows employing the ALE formulation

    NARCIS (Netherlands)

    van der Stelt, A.A.; Bor, Teunis Cornelis; Geijselaers, Hubertus J.M.; Akkerman, Remko; Huetink, Han; Merklein, M.; Hagenah, H.

    2012-01-01

    In this paper, a numerical problem with contacting solid metal flows is presented and solved with an arbitrary Lagrangian-Eulerian (ALE) finite element method. The problem consists of two domains which mechanically interact with each other. For this simulation a new free surface boundary condition

  13. Solid Phase Immunoassay Using Immunoreagents Immobilized on Inert Synthetic Resin Surfaces

    NARCIS (Netherlands)

    Hummelen, Jan C.; Luider, Theo; Wynberg, Hans

    1988-01-01

    A solid phase immunoassay comprises the steps of (a) immobilizing an immunoreagent on the surface of a carrier comprised of an inert synthetic resin selected from the group consisting of polyimides and polyfluorinated synthetic resins, (b) contacting the immunoreagent with a complementary

  14. Self-affine roughness influence on the friction coefficient for rubbers onto solid surfaces

    NARCIS (Netherlands)

    Palasantzas, G

    2004-01-01

    In this paper we investigate the influence of self-affine roughness on the friction coefficient mu(f) of a rubber body under incomplete contact onto a solid surface. The roughness is characterized by the rms amplitude w, the correlation length xi, and the roughness exponent H. It is shown that with

  15. Interactions between bacteria and solid surfaces in relation to bacterial transport in porous media

    NARCIS (Netherlands)

    Rijnaarts, H.H.M.

    1994-01-01

    Interactions between bacteria and solid surfaces strongly influence the behaviour of bacteria in natural and engineered ecosystems. Many biofilm reactors and terrestrial environments are porous media. The purpose of the research presented in this thesis is to gain a better insight into the

  16. Theoretical investigation of van der Waals forces between solid surfaces at nanoscales

    NARCIS (Netherlands)

    Kudryavtsev, Y.V.; Gelinck, E.R.M.; Fischer, H.R.

    2009-01-01

    A theoretical investigation of van der Waals forces acting between two solid silicon surfaces at separations from zero to approximately 20 nm is presented. We focused our efforts on the analysis of different factors that can cause deviations from the classical pressure-distance dependence p ∼ 1/D3.

  17. Reflection of P and SV waves from free surface of an elastic solid ...

    Indian Academy of Sciences (India)

    The reflection phenomena of P and SV waves from free surface of an elastic solid with thermodiffusion is considered. The boundary conditions are solved to obtain a system of four non- homogeneous equations for reflection coefficients. These reflection coefficients are found to depend upon the angle of incidence of P and ...

  18. Technology and human purpose: the problem of solids transport on the Earth's surface

    Directory of Open Access Journals (Sweden)

    P. K. Haff

    2012-11-01

    Full Text Available Displacement of mass of limited deformability ("solids" on the Earth's surface is opposed by friction and (the analog of form resistance – impediments relaxed by rotational motion, self-powering of mass units, and transport infrastructure. These features of solids transport first evolved in the biosphere prior to the emergence of technology, allowing slope-independent, diffusion-like motion of discrete objects as massive as several tons, as illustrated by animal foraging and movement along game trails. However, high-energy-consumption technology powered by fossil fuels required a mechanism that could support fast advective transport of solids, i.e., long-distance, high-volume, high-speed, unidirectional, slope-independent transport across the land surface of materials like coal, containerized fluids, minerals, and economic goods. Pre-technology nature was able to sustain regional- and global-scale advection only in the limited form of piggybacking on geophysical flows of water (river sediment and air (dust. The appearance of a mechanism for sustained advection of solids independent of fluid flows and gravity appeared only upon the emergence of human purpose. Purpose enables solids advection by, in effect, simulating a continuous potential gradient, otherwise lacking, between discrete and widely separated fossil-fuel energy sources and sinks. Invoking purpose as a mechanism in solids advection is an example of the need to import anthropic principles and concepts into the language and methodology of modern Earth system dynamics. As part of the emergence of a generalized solids advection mechanism, several additional transport requirements necessary to the function of modern large-scale technological systems were also satisfied. These include spatially accurate delivery of advected payload, targetability to essentially arbitrarily located destinations (such as cities, and independence of structure of advected payload from transport mechanism. The

  19. Rupture and Spreading Dynamics of Lipid Membranes on a Solid Surface

    Science.gov (United States)

    Perazzo, Antonio; Shin, Sangwoo; Colosqui, Carlos; Young, Yuan-Nan; Stone, Howard A.

    2017-11-01

    The spreading of lipid membranes on solid surfaces is a dynamic phenomenon relevant to drug delivery, endocytosis, biofouling, and the synthesis of supported lipid bilayers. Current technological developments are limited by an incomplete understanding of the spreading and adhesion dynamics of a lipid bilayer under different physicochemical conditions. Here, we present recent experimental and theoretical results for the spreading of giant unilamellar vesicles (GUVs), where the vesicle shell consists of a lipid bilayer. In particular, we study the effect of different background ion concentrations, osmolarity mismatches between the interior and the exterior of the vesicles, and different surface chemistries of the glass substrate. In all of the studied cases, we observe a delay time before a GUV in contact with the solid surface eventually ruptures. The rupture kinetics and subsequent spreading dynamics is controlled by the ionic screening within the thin film of liquid between the vesicle and the surface. Different rupture mechanisms, mobilities of the spreading vesicle, and degrees of substrate coverage are observed by varying the electrolyte concentration, solid surface charge, and osmolarity mismatch.

  20. In Situ Adsorption Studies at the Solid/Liquid Interface:Characterization of Biological Surfaces and Interfaces Using SumFrequency Generation Vibrational Spectroscopy, Atomic Force Microscopy,and Quartz Crystal Microbalance

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Diana Christine [Univ. of California, Berkeley, CA (United States)

    2006-01-01

    Sum frequency generation (SFG) vibrational spectroscopy, atomic force microscopy (AFM), and quartz crystal microbalance (QCM) have been used to study the molecular surface structure, surface topography and mechanical properties, and quantitative adsorbed amount of biological molecules at the solid-liquid interface. The molecular-level behavior of designed peptides adsorbed on hydrophobic polystyrene and hydrophilic silica substrates has been examined as a model of protein adsorption on polymeric biomaterial surfaces. Proteins are such large and complex molecules that it is difficult to identify the features in their structure that lead to adsorption and interaction with solid surfaces. Designed peptides which possess secondary structure provide simple model systems for understanding protein adsorption. Depending on the amino acid sequence of a peptide, different secondary structures (α-helix and β-sheet) can be induced at apolar (air/liquid or air/solid) interfaces. Having a well-defined secondary structure allows experiments to be carried out under controlled conditions, where it is possible to investigate the affects of peptide amino acid sequence and chain length, concentration, buffering effects, etc. on adsorbed peptide structure. The experiments presented in this dissertation demonstrate that SFG vibrational spectroscopy can be used to directly probe the interaction of adsorbing biomolecules with a surface or interface. The use of well designed model systems aided in isolation of the SFG signal of the adsorbing species, and showed that surface functional groups of the substrate are sensitive to surface adsorbates. The complementary techniques of AFM and QCM allowed for deconvolution of the effects of surface topography and coverage from the observed SFG spectra. Initial studies of biologically relevant surfaces are also presented: SFG spectroscopy was used to study the surface composition of common soil bacteria for use in bioremediation of nuclear waste.

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

    Science.gov (United States)

    Rolland, A.; Aufray, B.

    1985-10-01

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

  2. Determination of biocides and pesticides by on-line solid phase extraction coupled with mass spectrometry and their behaviour in wastewater and surface water.

    Science.gov (United States)

    Singer, Heinz; Jaus, Sylvia; Hanke, Irene; Lück, Alfred; Hollender, Juliane; Alder, Alfredo C

    2010-10-01

    This study focused on the input of hydrophilic biocides into the aquatic environment and on the efficiency of their removal in conventional wastewater treatment by a mass flux analysis. A fully automated method consisting of on-line solid phase extraction coupled to LC-ESI-MS/MS was developed and validated for the simultaneous trace determination of different biocidal compounds (1,2-benzisothiazoline-3-one (BIT), 3-Iodo-2-propynylbutyl-carbamate (IPBC), irgarol 1051 and 2-N-octyl-4-isothiazolinone (octhilinone, OIT), carbendazim, diazinon, diuron, isoproturon, mecoprop, terbutryn and terbutylazine) and pharmaceuticals (diclofenac and sulfamethoxazole) in wastewater and surface water. In the tertiary effluent, the highest average concentrations were determined for mecoprop (1010 ng/L) which was at comparable levels as the pharmaceuticals diclofenac (690 ng/L) and sulfamethoxazole (140 ng/L) but 1-2 orders of magnitude higher than the other biocidal compounds. Average eliminations for all compounds were usually below 50%. During rain events, increased residual amounts of biocidal contaminants are discharged to receiving surface waters. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  3. Effect of hydrophilic defects on water transport in MFI zeolites.

    Science.gov (United States)

    Humplik, Thomas; Raj, Rishi; Maroo, Shalabh C; Laoui, Tahar; Wang, Evelyn N

    2014-06-10

    The subnanometer pore structure of zeolites and other microporous materials has been proposed to act as a molecular sieve for various water separation technologies. However, due to the increased interaction between the solid and water in these nanoconfined spaces, it is unclear which type of interface, be it hydrophilic or hydrophobic, offers an advantageous medium for enhancing transport properties. In this work, we probe the role of hydrophilic defects on the transport of water inside the microporous hydrophobic MFI zeolite pore structure via combined sorption and high-pressure infiltration experiments. While the inclusion of defects was observed to increase the amount of water within the zeolite pore network by up to 7 times at the saturation pressure, the diffusivity of this infiltrated water was lowered by up to 2 orders of magnitude in comparison to that of water within the nearly defect-free hydrophobic MFI zeolite. Subsequently, the permeability of water within the more defective MFI zeolite was an order of magnitude lower than that of the nearly defect-free zeolite. The results from these experiments suggest that the intrinsic hydrophobic pore structure of MFI zeolites can facilitate faster water transport due to the decreased attraction between the water and the defect-free surface. While the strong attraction of water to the defects allows for water to infiltrate the porous network at lower pressures, the results suggest that this strong attraction decreases the mobility of the infiltrated water. The insights gained from this study can be utilized to improve the design of future membranes for water desalination and other separation techniques.

  4. Epitaxy of the bound water phase on hydrophilic surfaces of biopolymers as key mechanism of microwave radiation effects on living objects.

    Science.gov (United States)

    Kuznetsov, Denis B; Orlova, Ekaterina V; Neschislyaev, Valery A; Volkhin, Igor L; Izmestiev, Igor V; Lunegov, Igor V; Balandina, Alevtina V; Dianova, Dina G

    2017-06-01

    The research investigates the mechanism of microwave radiation effects on biological characteristics and structural-dynamic parameters of a sensor bioluminescence system. The research objects are a sterile growth medium (fish meal hydrolisate) and a bacterial culture. It has been established that irradiation causes changes of the growth medium spectral properties within the range of 200-350nm. Changes take place in the intensity and character of luminescence, as well as in relaxation parameters of nuclear magnetic resonance, growth characteristics of the bacterial culture, its cellular morphology and surface topology. The research results enabled us to establish the mechanisms of primary molecular processes that occur when the bacterial culture is exposed to microwave radiation. Transformation of the dynamic-structural state of adsorbed water phases on biopolymer surfaces has been found to be the key factor in the mechanism of microwave effects on living and water-containing objects. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Analysis of underground and surface waters of the dump of the solid communal waste

    Directory of Open Access Journals (Sweden)

    Almášová Kristína

    1997-06-01

    Full Text Available The paper deals with the contamination of underground and surface waters in the surroundings of the dump of the solid communal waste at the locality Cemjata in the East Slovakia,as well as with the development of the contamination in the surrounding of the dump depending on the time on the basis of the analysisof samples withdrawn from the net of drillholes in the observed area. In the area investigated there is described geological, geomorphological, climatic and hydrogeological situation, as well as the dump itself. The results acquired show that the contamination of the area brought about by medium size industrial and agricultural activity in the vicinity of the dump of the solid communal waste and inside the area investigated is comparable with the dangerous effects of the dump of the solid communal waste.

  6. Visualization and optimization of cavitation activity at a solid surface in high frequency ultrasound fields.

    Science.gov (United States)

    Kauer, Markus; Belova-Magri, Valentina; Cairós, Carlos; Schreier, Hans-Jürgen; Mettin, Robert

    2017-01-01

    Despite the increasing use of high frequency ultrasound in heterogeneous reactions, knowledge about the spatial distribution of cavitation bubbles at the irradiated solid surface is still lacking. This gap hinders controllable surface sonoreactions. Here we present an optimization study of the cavitation bubble distribution at a solid sample using sonoluminescence and sonochemiluminescence imaging. The experiments were performed at three ultrasound frequencies, namely 580, 860 and 1142kHz. We found that position and orientation of the sample to the transducer, as well as its material properties influence the distribution of active cavitation bubbles at the sample surface in the reactor. The reason is a significant modification of the acoustic field due to reflections and absorption of the ultrasonic wave by the solid. This is retraced by numerical simulations employing the Finite Element Method, yielding reasonable agreement of luminescent zones and high acoustic pressure amplitudes in 2D simulations. A homogeneous coverage of the test sample surface with cavitation is finally reached at nearly vertical inclination with respect to the incident wave. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zdziennicka, Anna; Szymczyk, Katarzyna; Krawczyk, Joanna; Jańczuk, Bronisław, E-mail: bronislaw.janczuk@poczta.umcs.lublin.pl

    2017-05-31

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

  8. A Variational Model for Two-Phase Immiscible Electroosmotic Flow at Solid Surfaces

    KAUST Repository

    Shao, Sihong

    2012-01-01

    We develop a continuum hydrodynamic model for two-phase immiscible flows that involve electroosmotic effect in an electrolyte and moving contact line at solid surfaces. The model is derived through a variational approach based on the Onsager principle of minimum energy dissipation. This approach was first presented in the derivation of a continuum hydrodynamic model for moving contact line in neutral two-phase immiscible flows (Qian, Wang, and Sheng, J. Fluid Mech. 564, 333-360 (2006)). Physically, the electroosmotic effect can be formulated by the Onsager principle as well in the linear response regime. Therefore, the same variational approach is applied here to the derivation of the continuum hydrodynamic model for charged two-phase immiscible flows where one fluid component is an electrolyte exhibiting electroosmotic effect on a charged surface. A phase field is employed to model the diffuse interface between two immiscible fluid components, one being the electrolyte and the other a nonconductive fluid, both allowed to slip at solid surfaces. Our model consists of the incompressible Navier-Stokes equation for momentum transport, the Nernst-Planck equation for ion transport, the Cahn-Hilliard phase-field equation for interface motion, and the Poisson equation for electric potential, along with all the necessary boundary conditions. In particular, all the dynamic boundary conditions at solid surfaces, including the generalized Navier boundary condition for slip, are derived together with the equations of motion in the bulk region. Numerical examples in two-dimensional space, which involve overlapped electric double layer fields, have been presented to demonstrate the validity and applicability of the model, and a few salient features of the two-phase immiscible electroosmotic flows at solid surface. The wall slip in the vicinity of moving contact line and the Smoluchowski slip in the electric double layer are both investigated. © 2012 Global-Science Press.

  9. Prediction of Ablation Rates from Solid Surfaces Exposed to High Temperature Gas Flow

    Science.gov (United States)

    Akyuzlu, Kazim M.; Coote, David

    2013-01-01

    A mathematical model and a solution algorithm is developed to study the physics of high temperature heat transfer and material ablation and identify the problems associated with the flow of hydrogen gas at very high temperatures and velocities through pipes and various components of Nuclear Thermal Rocket (NTR) motors. Ablation and melting can be experienced when the inner solid surface of the cooling channels and the diverging-converging nozzle of a Nuclear Thermal Rocket (NTR) motor is exposed to hydrogen gas flow at temperatures around 2500 degrees Kelvin and pressures around 3.4 MPa. In the experiments conducted on typical NTR motors developed in 1960s, degradation of the cooling channel material (cracking in the nuclear fuel element cladding) and in some instances melting of the core was observed. This paper presents the results of a preliminary study based on two types of physics based mathematical models that were developed to simulate the thermal-hydrodynamic conditions that lead to ablation of the solid surface of a stainless steel pipe exposed to high temperature hydrogen gas near sonic velocities. One of the proposed models is one-dimensional and assumes the gas flow to be unsteady, compressible and viscous. An in-house computer code was developed to solve the conservations equations of this model using a second-order accurate finite-difference technique. The second model assumes the flow to be three-dimensional, unsteady, compressible and viscous. A commercial CFD code (Fluent) was used to solve the later model equations. Both models assume the thermodynamic and transport properties of the hydrogen gas to be temperature dependent. In the solution algorithm developed for this study, the unsteady temperature of the pipe is determined from the heat equation for the solid. The solid-gas interface temperature is determined from an energy balance at the interface which includes heat transfer from or to the interface by conduction, convection, radiation, and

  10. Capillary instability on a hydrophilic stripe

    Science.gov (United States)

    Speth, Raymond L.; Lauga, Eric

    2009-07-01

    A recent experiment showed that cylindrical segments of water filling a hydrophilic stripe on an otherwise hydrophobic surface display a capillary instability when their volume is increased beyond the critical volume at which their apparent contact angle on the surface reaches 90° (Gau et al 1999 Science 283 46-9). Surprisingly, the fluid segments did not break up into droplets—as would be expected for a classical Rayleigh-Plateau instability—but instead displayed a long-wavelength instability where all excess fluid gathered in a single bulge along each stripe. We consider here the dynamics of the flow instability associated with this setup. We perform a linear stability analysis of the capillary flow problem in the inviscid limit. We first confirm previous work showing that all cylindrical segments are linearly unstable if (and only if) their apparent contact angle is larger than 90°. We then demonstrate that the most unstable wavenumber for the surface perturbation decreases to zero as the apparent contact angle of the fluid on the surface approaches 90°, allowing us to re-interpret the creation of bulges in the experiment as a zero-wavenumber capillary instability. A variation of the stability calculation is also considered for the case of a hydrophilic stripe located on a wedge-like geometry.

  11. Capillary instability on a hydrophilic stripe

    Energy Technology Data Exchange (ETDEWEB)

    Speth, Raymond L [Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Lauga, Eric [Department of Mechanical and Aerospace Engineering, University of California, San Diego, 9500 Gilman Dr, La Jolla, CA 92093-0411 (United States)], E-mail: elauga@ucsd.edu

    2009-07-15

    A recent experiment showed that cylindrical segments of water filling a hydrophilic stripe on an otherwise hydrophobic surface display a capillary instability when their volume is increased beyond the critical volume at which their apparent contact angle on the surface reaches 90 deg. (Gau et al 1999 Science 283 46-9). Surprisingly, the fluid segments did not break up into droplets-as would be expected for a classical Rayleigh-Plateau instability-but instead displayed a long-wavelength instability where all excess fluid gathered in a single bulge along each stripe. We consider here the dynamics of the flow instability associated with this setup. We perform a linear stability analysis of the capillary flow problem in the inviscid limit. We first confirm previous work showing that all cylindrical segments are linearly unstable if (and only if) their apparent contact angle is larger than 90 deg. We then demonstrate that the most unstable wavenumber for the surface perturbation decreases to zero as the apparent contact angle of the fluid on the surface approaches 90 deg, allowing us to re-interpret the creation of bulges in the experiment as a zero-wavenumber capillary instability. A variation of the stability calculation is also considered for the case of a hydrophilic stripe located on a wedge-like geometry.

  12. Atomistic modelling of evaporation and explosive boiling of thin film liquid argon over internally recessed nanostructured surface

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, Mohammad Nasim, E-mail: nasim@me.buet.ac.bd.com; Shavik, Sheikh Mohammad, E-mail: shavik@me.buet.ac.bd.com; Rabbi, Kazi Fazle, E-mail: rabbi35.me10@gmail.com; Haque, Mominul, E-mail: mominulmarup@gmail.com [Department of Mechanical Engineering, Bangladesh University of Engineering & Technology (BUET) Dhaka-1000 (Bangladesh)

    2016-07-12

    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. Hydrophilic Hollow Molecularly Imprinted Polymer Microparticles with Photo- and Thermoresponsive Template Binding and Release Properties in Aqueous Media.

    Science.gov (United States)

    Li, Chenxi; Ma, Yue; Niu, Hui; Zhang, Huiqi

    2015-12-16

    A facile, general, and efficient approach to prepare hydrophilic hollow molecularly imprinted polymer (MIP) microparticles with photo- and thermoresponsive template binding and release behaviors in aqueous media is described, which includes the preparation of uniform "living" silica submicrospheres bearing surface atom transfer radical polymerization (ATRP)-initiating groups (i.e., alkyl halide groups) via a one-pot sol-gel method, their subsequent grafting of azobenzene (azo)-containing MIP shell and poly(N-isopropylacrylamide)-block-poly(2-hydroxyethyl methacrylate) (PNIPAAm-b-PHEMA) brushes via successive surface-initiated ATRP, and final removal of the silica core. The successful synthesis of such hydrophilic hollow MIP microparticles was confirmed with SEM, FT-IR, water dispersion stability, and static contact angle studies. They proved to show apparently higher template binding capacities than the corresponding solid ones and obvious photo- and thermoresponsive template binding properties in aqueous solutions. Moreover, their pronounced light- and temperature-controlled template release in aqueous media was also demonstrated. In particular, the introduction of PNIPAAm-b-PHEMA brushes onto hollow MIP microparticles imparted them with high surface hydrophilicity both below and above the lower critical solution temperature of PNIPAAm, which paves the way for their applications in such areas as controlled drug/chemical delivery and smart bioanalysis.

  14. Particle Engineering in Pharmaceutical Solids Processing: Surface Energy 
Considerations

    Science.gov (United States)

    Williams, Daryl R.

    2015-01-01

    During the past 10 years particle engineering in the pharmaceutical industry has become a topic of increasing importance. Engineers and pharmacists need to understand and control a range of key unit manufacturing operations such as milling, granulation, crystallisation, powder mixing and dry powder inhaled drugs which can be very challenging. It has now become very clear that in many of these particle processing operations, the surface energy of the starting, intermediate or final products is a key factor in understanding the processing operation and or the final product performance. This review will consider the surface energy and surface energy heterogeneity of crystalline solids, methods for the measurement of surface energy, effects of milling on powder surface energy, adhesion and cohesion on powder mixtures, crystal habits and surface energy, surface energy and powder granulation processes, performance of DPI systems and finally crystallisation conditions and surface energy. This review will conclude that the importance of surface energy as a significant factor in understanding the performance of many particulate pharmaceutical products and processes has now been clearly established. It is still nevertheless, work in progress both in terms of development of methods and establishing the limits for when surface energy is the key variable of relevance. PMID:25876912

  15. Modelling interstellar physics and chemistry: implications for surface and solid-state processes.

    Science.gov (United States)

    Williams, David; Viti, Serena

    2013-07-13

    We discuss several types of regions in the interstellar medium of the Milky Way and other galaxies in which the chemistry appears to be influenced or dominated by surface and solid-state processes occurring on or in interstellar dust grains. For some of these processes, for example, the formation of H₂ molecules, detailed experimental and theoretical approaches have provided excellent fundamental data for incorporation into astrochemical models. In other cases, there is an astrochemical requirement for much more laboratory and computational study, and we highlight these needs in our description. Nevertheless, in spite of the limitations of the data, it is possible to infer from astrochemical modelling that surface and solid-state processes play a crucial role in astronomical chemistry from early epochs of the Universe up to the present day.

  16. Solid state and surface effects in thin-film molecular switches.

    Science.gov (United States)

    Hopwood, Jonathan P; Ciszek, Jacob W

    2017-07-01

    Thin-films of three dihydroindolizine molecular switches were monitored via polarization modulation infrared reflection absorption spectroscopy to quantify solid state and surface-based inhibition of switching as a function of irradiation time. In the solid state, the molecular switches diverged dramatically with flexible alkyl substituents resulting in switching rates up to three times that of switches containing rigid analogs. For thin-films, decreasing film thickness from 30 nm to approximately 4 molecules thick resulted in an increase in inhibition. This was found to be consistent across all molecules regardless of structure. Increased inhibition is isolated as a metal/molecule interaction, and its consistency across structure is suggestive of energy transfer to the surface. These molecular switches highlight the interplay between molecular design, electronic structure, and switching efficiency.

  17. Dynamics at Solid State Surfaces and Interfaces, Volume 1 Current Developments

    CERN Document Server

    Bovensiepen, Uwe; Wolf, Martin

    2010-01-01

    This two-volume work covers ultrafast structural and electronic dynamics of elementary processes at solid surfaces and interfaces, presenting the current status of photoinduced processes. Providing valuable introductory information for newcomers to this booming field of research, it investigates concepts and experiments, femtosecond and attosecond time-resolved methods, as well as frequency domain techniques. The whole is rounded off by a look at future developments.

  18. A conserved fungal glycosyltransferase facilitates pathogenesis of plants by enabling hyphal growth on solid surfaces.

    Science.gov (United States)

    King, Robert; Urban, Martin; Lauder, Rebecca P; Hawkins, Nichola; Evans, Matthew; Plummer, Amy; Halsey, Kirstie; Lovegrove, Alison; Hammond-Kosack, Kim; Rudd, Jason J

    2017-10-01

    Pathogenic fungi must extend filamentous hyphae across solid surfaces to cause diseases of plants. However, the full inventory of genes which support this is incomplete and many may be currently concealed due to their essentiality for the hyphal growth form. During a random T-DNA mutagenesis screen performed on the pleomorphic wheat (Triticum aestivum) pathogen Zymoseptoria tritici, we acquired a mutant unable to extend hyphae specifically when on solid surfaces. In contrast "yeast-like" growth, and all other growth forms, were unaffected. The inability to extend surface hyphae resulted in a complete loss of virulence on plants. The affected gene encoded a predicted type 2 glycosyltransferase (ZtGT2). Analysis of >800 genomes from taxonomically diverse fungi highlighted a generally widespread, but discontinuous, distribution of ZtGT2 orthologues, and a complete absence of any similar proteins in non-filamentous ascomycete yeasts. Deletion mutants of the ZtGT2 orthologue in the taxonomically un-related fungus Fusarium graminearum were also severely impaired in hyphal growth and non-pathogenic on wheat ears. ZtGT2 expression increased during filamentous growth and electron microscopy on deletion mutants (ΔZtGT2) suggested the protein functions to maintain the outermost surface of the fungal cell wall. Despite this, adhesion to leaf surfaces was unaffected in ΔZtGT2 mutants and global RNAseq-based gene expression profiling highlighted that surface-sensing and protein secretion was also largely unaffected. However, ΔZtGT2 mutants constitutively overexpressed several transmembrane and secreted proteins, including an important LysM-domain chitin-binding virulence effector, Zt3LysM. ZtGT2 likely functions in the synthesis of a currently unknown, potentially minor but widespread, extracellular or outer cell wall polysaccharide which plays a key role in facilitating many interactions between plants and fungi by enabling hyphal growth on solid matrices.

  19. A conserved fungal glycosyltransferase facilitates pathogenesis of plants by enabling hyphal growth on solid surfaces.

    Directory of Open Access Journals (Sweden)

    Robert King

    2017-10-01

    Full Text Available Pathogenic fungi must extend filamentous hyphae across solid surfaces to cause diseases of plants. However, the full inventory of genes which support this is incomplete and many may be currently concealed due to their essentiality for the hyphal growth form. During a random T-DNA mutagenesis screen performed on the pleomorphic wheat (Triticum aestivum pathogen Zymoseptoria tritici, we acquired a mutant unable to extend hyphae specifically when on solid surfaces. In contrast "yeast-like" growth, and all other growth forms, were unaffected. The inability to extend surface hyphae resulted in a complete loss of virulence on plants. The affected gene encoded a predicted type 2 glycosyltransferase (ZtGT2. Analysis of >800 genomes from taxonomically diverse fungi highlighted a generally widespread, but discontinuous, distribution of ZtGT2 orthologues, and a complete absence of any similar proteins in non-filamentous ascomycete yeasts. Deletion mutants of the ZtGT2 orthologue in the taxonomically un-related fungus Fusarium graminearum were also severely impaired in hyphal growth and non-pathogenic on wheat ears. ZtGT2 expression increased during filamentous growth and electron microscopy on deletion mutants (ΔZtGT2 suggested the protein functions to maintain the outermost surface of the fungal cell wall. Despite this, adhesion to leaf surfaces was unaffected in ΔZtGT2 mutants and global RNAseq-based gene expression profiling highlighted that surface-sensing and protein secretion was also largely unaffected. However, ΔZtGT2 mutants constitutively overexpressed several transmembrane and secreted proteins, including an important LysM-domain chitin-binding virulence effector, Zt3LysM. ZtGT2 likely functions in the synthesis of a currently unknown, potentially minor but widespread, extracellular or outer cell wall polysaccharide which plays a key role in facilitating many interactions between plants and fungi by enabling hyphal growth on solid matrices.

  20. Surface clogging process modeling of suspended solids during urban stormwater aquifer recharge.

    Science.gov (United States)

    Wang, Zijia; Du, Xinqiang; Yang, Yuesuo; Ye, Xueyan

    2012-01-01

    Aquifer recharge, which uses urban stormwater, is an effective technique to control the negative effects of groundwater over-exploitation, while clogging problems in infiltration systems remain the key restricting factor in broadening its practice. Quantitative understanding of the clogging process is still very poor. A laboratory study was conducted to understand surface physical clogging processes, with the primary aim of developing a model for predicting suspended solid clogging processes before aquifer recharge projects start. The experiments investigated the clogging characteristics of different suspended solid sizes in recharge water by using a series of one-dimensional fine quartz sand columns. The results showed that the smaller the suspended particles in recharge water, the farther the distance of movement and the larger the scope of clogging in porous media. Clogging extents in fine sand were 1 cm, for suspended particle size ranging from 0.075 to 0.0385 mm, and 2 cm, for particles less than 0.0385 mm. In addition, clogging development occurred more rapidly for smaller suspended solid particles. It took 48, 42, and 36 hr respectively, for large-, medium-, and small-sized particles to reach pre-determined clogging standards. An empirical formula and iteration model for the surface clogging evolution process were derived. The verification results obtained from stormwater recharge into fine sand demonstrated that the model could reflect the real laws of the surface clogging process.

  1. Changes in contact angle providing evidence for surface alteration in multi-component solid foods

    Science.gov (United States)

    Reinke, Svenja K.; Hauf, Katharina; Vieira, Josélio; Heinrich, Stefan; Palzer, Stefan

    2015-11-01

    Chocolate blooming, one of the major problems in the confectionery industry, is the formation of visible white spots or a greyish haze on the surface of chocolate products due to large sugar or fat crystals on the surface. This leads to aesthetic changes and deterioration of taste and thus large sales losses for the confectionery industry due to consumer complaints. Chocolate blooming is often related to migration of lipids or sugar molecules to the chocolate surface, where they recrystallize with an associated polymorphic change of crystal structure on the surface. The wetting behaviour from contact angle measurements gives further insight into surface properties and is needed to determine surface energies and to evaluate possible migration mechanisms and preferred pathways. Therefore, an equilibrium contact angle is needed which is not directly accessible and is influenced by surface texture and interaction between solid and test liquid. In this study, the surface of cocoa butter and conventional chocolates was characterized by measuring the contact angle with the sessile drop protocol. The influence of roughness, test liquid and pre-crystallization of the samples as well as the storage temperature were investigated. In case of no pre-crystallization, a change in surface properties due to storage at 20 °C was detected, whereas samples stored at 30 °C showed the same wetting behaviour as fresh samples. This is associated with polymorphic transformation from thermodynamically less stable crystals to more stable configurations.

  2. Adsorption of fluids on solid surfaces: A route toward very dense layers

    Energy Technology Data Exchange (ETDEWEB)

    Sartarelli, S.A. [Instituto de Desarrollo Humano, Universidad Nacional de General Sarmiento, San Miguel (Argentina); Szybisz, L., E-mail: szybisz@tandar.cnea.gov.ar [Laboratorio TANDAR, Departamento de Fisica, Comision Nacional de Energia Atomica, RA-1429 Buenos Aires (Argentina); Departamento de Fiica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas, RA-1033 Buenos Aires (Argentina)

    2012-08-15

    Adsorption of Xe on single planar walls is investigated in the frame of a density functional theory. The strength of the adsorbate-substrate attraction is changed by considering surfaces of Cs, Na, Li, and Mg. The behavior is analyzed by varying the temperature T (between the triple point T{sub t} and the critical T{sub c}) and the coverage {Gamma}{sub Script-Small-L }. The obtained adsorption isotherms exhibit a variety of wetting situations. Density profiles are reported. It is shown that for strongly attractive surfaces the adsorbed liquid becomes very dense reaching densities characteristic of solids.

  3. Structured Extended Finite Element Methods of Solids Defined by Implicit Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Belytschko, T; Mish, K; Moes, N; Parimi, C

    2002-11-17

    A paradigm is developed for generating structured finite element models from solid models by means of implicit surface definitions. The implicit surfaces are defined by radial basis functions. Internal features, such as material interfaces, sliding interfaces and cracks are treated by enrichment techniques developed in the extended finite element method (X-FEM). Methods for integrating the weak form for such models are proposed. These methods simplify the generation of finite element models. Results presented for several examples show that the accuracy of this method is comparable to standard unstructured finite element methods.

  4. Experimental investigation of picoliter liquid drops evaporation on a heated solid surface

    Science.gov (United States)

    Kirichenko, D. P.; Zaitsev, D. V.; Kabov, O. A.

    2017-11-01

    This paper presents a study of the evaporation of sessile picoliter liquid drops on a heated solid surface. It has been shown that during evaporation diameter of the drop is almost constant (the contact line is pinned) and starts to decrease only at the final moment of drop life. It has been shown that the specific evaporation rate of a droplet (droplet weight loss per unit time per unit droplet surface area) is not constant over time: it gradually grows with time up to a maximum, but at the final stage, when the height of the drop becomes on the order of 1 μm, it decreases rapidly.

  5. Surface chemical properties of novel high surface area solids synthesized from coal fly ash

    CSIR Research Space (South Africa)

    Pretorius, PJ

    2003-07-23

    Full Text Available ESCAMicroprobe.Scanningelectronmicroscopy (SEM) was performed on a Philips XL 30 scanning electron microscope to which an EDAX DX4 energy dispersive X-ray analysersystem(EDS)wascoupled,whichalsoallowedelemen- tal compositions to be estimated. 2.3. Potentiometric Titrations Approximately 0.05 g... of the solid was accurately weighed out and transferred to a thermostatted pyrex titration vessel con- taining20.00cm3 of0.3moldm?3 NaNO3 (MerckGR)and2.00cm3 of0.1moldm?3 NaOHina0.3moldm?3 NaNO3 backgroundelec- trolyte solution. For metal adsorption studies...

  6. Continuous versus Arrested Spreading of Biofilms at Solid-Gas Interfaces: The Role of Surface Forces

    Science.gov (United States)

    Trinschek, Sarah; John, Karin; Lecuyer, Sigolène; Thiele, Uwe

    2017-08-01

    We introduce and analyze a model for osmotically spreading bacterial colonies at solid-air interfaces that includes wetting phenomena, i.e., surface forces. The model is based on a hydrodynamic description for liquid suspensions which is supplemented by bioactive processes. We show that surface forces determine whether a biofilm can expand laterally over a substrate and provide experimental evidence for the existence of a transition between continuous and arrested spreading for Bacillus subtilis biofilms. In the case of arrested spreading, the lateral expansion of the biofilm is confined, albeit the colony is biologically active. However, a small reduction in the surface tension of the biofilm is sufficient to induce spreading. The incorporation of surface forces into our hydrodynamic model allows us to capture this transition in biofilm spreading behavior.

  7. 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.

  8. Rapid and simultaneous determination of hexapeptides (Ac-EEMQRR-amide and H2N-EEMQRR-amide) in anti-wrinkle cosmetics by hydrophilic interaction liquid chromatography-solid phase extraction preparation and hydrophilic interaction liquid chromatography with tandem mass spectrometry.

    Science.gov (United States)

    Zhou, Wanlong; Wang, Perry G; Krynitsky, Alexander J; Rader, Jeanne I

    2011-11-04

    A rapid method for the simultaneous determination of Ac-EEMQRR-amide and H(2)N-EEMQRR-amide in cosmetic products was developed and evaluated. This analytical procedure involved extracting samples with 0.1:0.1:85:15 (v:v) trifluoroacetic acid (TFA):formic acid:acetonitrile (ACN):water and determination by hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC-MS/MS). Samples showing serious ion suppression were further cleaned up using HILIC-SPE prior to HILIC-MS/MS analysis. Stable isotopically labeled peptides, corresponding to the above two peptides, were used as internal standards to correct for loss of recovery and matrix effects. Electrospray ionization (ESI) in the positive mode was used. The linear range was 2.0-1000 ng/mL for Ac-EEMQRR-amide and 25.0-2500 ng/mL for H(2)N-EEMQRR-amide. Thirteen commercial products were analyzed for the two peptides using this method. The amounts of Ac-EEMQRR-amide in the samples ranged from none detected to 42.3 μg/g. H(2)N-EEMQRR-amide was not detected in any of the samples. The recoveries for Ac-EEMQRR-amide and H(2)N-EEMQRR-amide ranged from 85% to 110% and 84% to 119%, respectively, at the spiking level of 30 μg/g. Published by Elsevier B.V.

  9. In situ investigation the photolysis of the PAHs adsorbed on mangrove leaf surfaces by synchronous solid surface fluorimetry.

    Directory of Open Access Journals (Sweden)

    Ping Wang

    Full Text Available An established synchronous solid surface fluorimetry (S-SSF was utilized for in situ study the photolysis processes of anthracene (An and pyrene (Py adsorbed on the leaf surfaces of Kandelia obovata seedlings (Ko and Aegiceras corniculata (L. Blanco seedlings (Ac. Experimental results demonstrated that the photolysis of An and Py adsorbed on the leaf surfaces of two mangrove species under the laboratory conditions, followed first-order kinetics with their photolysis rates in the order of Ac>Ko. In addition, with the same amount of substances, the photolysis rate of An adsorbed on the same mangrove leaf surfaces was much faster than the adsorbed Py. In order to investigate further, the photolysis processes of An and Py in water were also studied for comparison. And the photolysis of An and Py in water also followed first-order kinetics. Moreover, for the same initial amount, the photolysis rate of the PAH in water was faster than that adsorbed on the leaf surfaces of two mangrove species. Therefore, photochemical behaviors of PAHs were dependent not only on their molecular structures but also the physical-chemical properties of the substrates on which they are adsorbed.

  10. The study of an interaction of solid particles with various surfaces using TSM sensors.

    Science.gov (United States)

    Zhang, Qiliang; Lec, Ryszard M; Pourrezaei, Kambiz

    2006-01-01

    The interaction of solid particles with various surfaces has been experiencing growing interest in many areas of nanotechnology, colloidal science, and biology. In this paper the interactions of solid particles with the surface of piezoelectric thickness shear mode (TSM) sensors have been studied. A mechanical model has been presented to evaluate the effect of particle loading on the behavior of a TSM sensor. The main sources contributing to the interaction, such as Van der Waals force, friction force, and electrostatic force, are discussed. Experiments have been designed for 10-100 microm particles on the 5-MHz and 10-MHz TSM sensors. It has been shown that the resonant frequencies of the TSM sensors might increase or decrease depending on the interaction conditions. The results have shown that the TSM sensor technique could provide the information on the mass/size of a particle and the binding energy between a particle and the sensor surface. This technique may find its applications in characterizing the properties of an interaction between particles and various surfaces.

  11. A Highly Selective Sensor for Cyanide in Organic Media and on Solid Surfaces

    Directory of Open Access Journals (Sweden)

    Belygona Barare

    2016-02-01

    Full Text Available The application of IR 786 perchlorate (IR-786 as a selective optical sensor for cyanide anion in both organic solution (acetonitrile (MeCN, 100% and solvent-free solid surfaces was demonstrated. In MeCN, IR-786 was selective to two anions in the following order: CN− > OH−. A significant change in the characteristic dark green color of IR-786 in MeCN to yellow was observed as a result of nucleophilic addition of CN− to the fluorophore, i.e., formation of IR 786-(CN, which was also verified by a blue shift in the 775 nm absorbance peak to 430 nm. A distinct green fluorescence emission from the IR-786-(CN in MeCN was also observed, which demonstrated the selectivity of IR-786 towards CN− in MeCN. Fluorescence emission studies of IR-786 showed that the lower detection limit and the sensitivity of IR-786 for CN− in MeCN was 0.5 μM and 0.5 to 8 μM, respectively. The potential use of IR-786 as a solvent-free solid state sensor for the selective sensing and monitoring of CN− in the environment was also demonstrated. On solvent-free solid state surfaces, the sensitivity of the IR-786 to CN− in water samples was in the range of 50–300 μM with minimal interference by OH−.

  12. Fast, Statistical Model of Surface Roughness for Ion-Solid Interaction Simulations and Efficient Code Coupling

    Science.gov (United States)

    Drobny, Jon; Curreli, Davide; Ruzic, David; Lasa, Ane; Green, David; Canik, John; Younkin, Tim; Blondel, Sophie; Wirth, Brian

    2017-10-01

    Surface roughness greatly impacts material erosion, and thus plays an important role in Plasma-Surface Interactions. Developing strategies for efficiently introducing rough surfaces into ion-solid interaction codes will be an important step towards whole-device modeling of plasma devices and future fusion reactors such as ITER. Fractal TRIDYN (F-TRIDYN) is an upgraded version of the Monte Carlo, BCA program TRIDYN developed for this purpose that includes an explicit fractal model of surface roughness and extended input and output options for file-based code coupling. Code coupling with both plasma and material codes has been achieved and allows for multi-scale, whole-device modeling of plasma experiments. These code coupling results will be presented. F-TRIDYN has been further upgraded with an alternative, statistical model of surface roughness. The statistical model is significantly faster than and compares favorably to the fractal model. Additionally, the statistical model compares well to alternative computational surface roughness models and experiments. Theoretical links between the fractal and statistical models are made, and further connections to experimental measurements of surface roughness are explored. This work was supported by the PSI-SciDAC Project funded by the U.S. Department of Energy through contract DOE-DE-SC0008658.

  13. Green's function nonequilibrium molecular dynamics method for solid surfaces and interfaces.

    Science.gov (United States)

    Kajita, Seiji

    2016-09-01

    This study presents a comprehensive procedure to calculate the exact dynamic Green's function of a harmonic semi-infinite solid and the time trajectories of the atoms, in the framework of the Green's function molecular dynamics. This Green's function properly describes the energy dissipation caused by excitations of the surface phonons, and the simulated atoms serve as well-defined thermo- and barostats for the nonequilibrium surface and interface systems. Moreover, the use of the exact dynamic Green's function coupled with a fast convolution algorithm significantly improves both the accuracy and the computing speed. The presented method is applied to a diamond (001) surface, and the results demonstrate that the properties of the nonreflecting boundary, the thermal fluctuations, and the energy dissipations involving long-wavelength phonons are correctly reproduced. These distinctive performances potentially allow us to reveal the nonequilibrium phenomena in a wide spectrum of applications such as catalysis, thermal transport, fracture mechanics, mechanochemistry, and tribology.

  14. Superstable Ultrathin Water Film Confined in a Hydrophilized Carbon Nanotube.

    Science.gov (United States)

    Tomo, Yoko; Askounis, Alexandros; Ikuta, Tatsuya; Takata, Yasuyuki; Sefiane, Khellil; Takahashi, Koji

    2018-02-13

    Fluids confined in a nanoscale space behave differently than in the bulk due to strong interactions between fluid molecules and solid atoms. Here, we observed water confined inside "open" hydrophilized carbon nanotubes (CNT), with diameter of tens of nanometers, using transmission electron microscopy (TEM). A 1-7 nm water film adhering to most of the inner wall surface was observed and remained stable in the high vacuum (order of 10 -5 Pa) of the TEM. The superstability of this film was attributed to a combination of curvature, nanoroughness, and confinement resulting in a lower vapor pressure for water and hence inhibiting its vaporization. Occasional, suspended ultrathin water film with thickness of 3-20 nm were found and remained stable inside the CNT. This film thickness is 1 order of magnitude smaller than the critical film thickness (about 40 nm) reported by the Derjaguin-Landau-Verwey-Overbeek theory and previous experimental investigations. The stability of the suspended ultrathin water film is attributed to the additional molecular interactions due to the extended water meniscus, which balances the rest of the disjoining pressures.

  15. Use of molecular beams for kinetic measurements of chemical reactions on solid surfaces

    Science.gov (United States)

    Zaera, Francisco

    2017-05-01

    In this review we survey the contributions that molecular beam experiments have provided to our understanding of the dynamics and kinetics of chemical interactions of gas molecules with solid surfaces. First, we describe the experimental details of the different instrumental setups and approaches available for the study of these systems under the ultrahigh vacuum conditions and with the model planar surfaces often used in modern surface-science experiments. Next, a discussion is provided of the most important fundamental aspects of the dynamics of chemical adsorption that have been elucidated with the help of molecular beam experiments, which include the development of potential energy surfaces, the determination of the different channels for energy exchange between the incoming molecules and the surface, the identification of adsorption precursor states, the understanding of dissociative chemisorption, the determination of the contributions of corrugation, steps, and other structural details of the surface to the adsorption process, the effect to molecular steering, the identification of avenues for assisting adsorption, and the molecular details associated with the kinetics of the uptake of adsorbates as a function of coverage. We follow with a summary of the work directed at the determination of kinetic parameters and mechanistic details of surface reactions associated with catalysis, mostly those promoted by late transition metals. This discussion we initiate with an overview of what has been learned about simple bimolecular reactions such as the oxidation of CO and H2 with O2 and the reaction of CO with NO, and continue with the review of the studies of more complex systems such as the oxidation of alcohols, the conversion of organic acids, the hydrogenation and isomerization of olefins, and the oxidative activation of alkanes under conditions of short contact times. Sections 6 and 7 of this review deal with the advances made in the use of molecular beams with

  16. Analysis of Rayleigh-Lamb Modes in Soft-solids with Application to Surface Wave Elastography

    Science.gov (United States)

    Benech, Nicolás; Grinspan, Gustavo; Aguiar, Sofía; Brum, Javier; Negreira, Carlos; tanter, Mickäel; Gennisson, Jean-Luc

    The goal of Surface Wave Elastography (SE) techniques is to estimate the shear elasticity of the sample by measuring the surface wave speed. In SE the thickness of the sample is often assumed to be infinite, in this way, the surface wave speed is directly linked to the sample's shear elasticity. However for many applications this assumption is not true. In this work, we study experimentally the Rayleigh-Lamb modes in soft solids of finite thickness to explore the optimal conditions for SWE. Experiments were carried out in three tissue mimicking phantoms of different thicknesses (10 mm, 20 mm and 60 mm) and same shear elasticity. The surface waves were generated at the surface of the phantom using piston attached to a mechanical vibrator. The central frequency of the excitation was varied between 60 Hz to 160 Hz. One component of the displacement field generated by the piston was measured at the surface and in the bulk of the sample trough a standard speckle tracking technique using a 256 element, 7.5 MHz central frequency linear array and an ultrasound ultrafast electronics. Finally, by measuring the phase velocity at each excitation frequency, velocity dispersion curves were obtained for each phantom. The results show that instead of a Rayleigh wave, zero order symmetric (S0) and antisymmetric (A0) Lamb modes are excited with this type of source. Moreover, in this study we show that due to the near field effects of the source, which are appreciable only in soft solids at low frequencies, both Lamb modes are separable in time and space. We show that while the Ao mode dominates close the source, the S0 mode dominates far away.

  17. Characterization of Silicon Nanocrystal Surfaces by Multidimensional Solid-State NMR Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hanrahan, Michael P. [Department; US DOE Ames Laboratory, Ames, Iowa 50011, United States; Fought, Ellie L. [Department; Windus, Theresa L. [Department; Wheeler, Lance M. [Chemistry; Anderson, Nicholas C. [Chemistry; Neale, Nathan R. [Chemistry; Rossini, Aaron J. [Department; US DOE Ames Laboratory, Ames, Iowa 50011, United States

    2017-11-17

    The chemical and photophysical properties of silicon nanocrystals (Si NCs) are strongly dependent on the chemical composition and structure of their surfaces. Here we use fast magic angle spinning (MAS) and proton detection to enable the rapid acquisition of dipolar and scalar 2D 1H-29Si heteronuclear correlation (HETCOR) solid-state NMR spectra and reveal a molecular picture of hydride-terminated and alkyl-functionalized surfaces of Si NCs produced in a nonthermal plasma. 2D 1H-29Si HETCOR and dipolar 2D 1H-1H multiple-quantum correlation spectra illustrate that resonances from surface mono-, di-, and trihydride groups cannot be resolved, contrary to previous literature assignments. Instead the 2D NMR spectra illustrate that there is large distribution of 1H and 29Si chemical shifts for the surface hydride species in both the as-synthesized and functionalized Si NCs. However, proton-detected 1H-29Si refocused INEPT experiments can be used to unambiguously differentiate NMR signals from the different surface hydrides. Varying the 29Si evolution time in refocused INEPT experiments and fitting the oscillation of the NMR signals allows for the relative populations of the different surface hydrides to be estimated. This analysis confirms that monohydride species are the predominant surface species on the as-synthesized Si NCs. A reduction in the populations of the di- and trihydrides is observed upon functionalization with alkyl groups, consistent with our previous hypothesis that the trihydride, or silyl (*SiH3), group is primarily responsible for initiating surface functionalization reactions. Density functional theory (DFT) calculations were used to obtain quantum chemical structural models of the Si NC surface and reproduce the observed 1H and 29Si chemical shifts. The approaches outlined here will be useful to obtain a more detailed picture of surface structures for Si NCs and other hydride-passivated nanomaterials.

  18. The behavior of novel hydrophilic composite bone cements in simulated body fluids.

    Science.gov (United States)

    Boesel, Luciano F; Fernandes, Maria H V; Reis, Rui L

    2004-08-15

    Composite bone cements were formulated with bioactive glass (MgO--SiO(2)--3CaO. P(2)O(5)) as the filler and hydrophilic matrix. The matrix was composed of a starch/cellulose acetate blend (SCA) as the solid component and a mixture of methylmethacrylate/acrylic acid (MMA/AA) as the liquid component. The curing parameters, mechanical properties, and bioactive behavior of these composite cements were determined. The addition of up to 30 wt % of glass improved both compressive modulus and yield strength and kept the maximum curing temperature at the same value presented by a typical acrylic-based commercial formulation. The lack of a strongly bonded interface (because no coupling agent was used) had important effects on the swelling and mechanical properties of the novel bone cements. However, bone cements containing AA did not show a bioactive behavior, because of the deleterious effect of this monomer on the calcium phosphate precipitation on the polymeric surfaces. Formulations without AA were prepared with MMA or 2-hydroxyethyl methacrylate (HEMA) as the liquid component. Only these formulations could form an apatite-like layer on their surface. These systems, therefore, are very promising: They are bioactive, hydrophilic, partially degradable, and present interesting mechanical properties. This combination of properties could facilitate the release of bioactive agents from the cement, allow bone ingrowth in the cement, and induce a press-fitting effect, improving the interfaces with both the prosthesis and the bone. Copyright 2004 Wiley Periodicals, Inc.

  19. Modeling Replenishment of Ultrathin Liquid Perfluoropolyether Z Films on Solid Surfaces Using Monte Carlo Simulation

    Directory of Open Access Journals (Sweden)

    M. S. Mayeed

    2014-01-01

    Full Text Available Applying the reptation algorithm to a simplified perfluoropolyether Z off-lattice polymer model an NVT Monte Carlo simulation has been performed. Bulk condition has been simulated first to compare the average radius of gyration with the bulk experimental results. Then the model is tested for its ability to describe dynamics. After this, it is applied to observe the replenishment of nanoscale ultrathin liquid films on solid flat carbon surfaces. The replenishment rate for trenches of different widths (8, 12, and 16 nms for several molecular weights between two films of perfluoropolyether Z from the Monte Carlo simulation is compared to that obtained solving the diffusion equation using the experimental diffusion coefficients of Ma et al. (1999, with room condition in both cases. Replenishment per Monte Carlo cycle seems to be a constant multiple of replenishment per second at least up to 2 nm replenished film thickness of the trenches over the carbon surface. Considerable good agreement has been achieved here between the experimental results and the dynamics of molecules using reptation moves in the ultrathin liquid films on solid surfaces.

  20. Surface strontium enrichment on highly active perovskites for oxygen electrocatalysis in solid oxide fuel cells

    KAUST Repository

    Crumlin, Ethan J.

    2012-01-01

    Perovskite oxides have high catalytic activities for oxygen electrocatalysis competitive to platinum at elevated temperatures. However, little is known about the oxide surface chemistry that influences the activity near ambient oxygen partial pressures, which hampers the design of highly active catalysts for many clean-energy technologies such as solid oxide fuel cells. Using in situ synchrotron-based, ambient pressure X-ray photoelectron spectroscopy to study the surface chemistry changes, we show that the coverage of surface secondary phases on a (001)-oriented La 0.8Sr 0.2CoO 3-δ (LSC) film becomes smaller than that on an LSC powder pellet at elevated temperatures. In addition, strontium (Sr) in the perovskite structure enriches towards the film surface in contrast to the pellet having no detectable changes with increasing temperature. We propose that the ability to reduce surface secondary phases and develop Sr-enriched perovskite surfaces of the LSC film contributes to its enhanced activity for O 2 electrocatalysis relative to LSC powder-based electrodes. © 2012 The Royal Society of Chemistry.

  1. Heterogeneous catalytic materials solid state chemistry, surface chemistry and catalytic behaviour

    CERN Document Server

    Busca, Guido

    2014-01-01

    Heterogeneous Catalytic Materials discusses experimental methods and the latest developments in three areas of research: heterogeneous catalysis; surface chemistry; and the chemistry of catalysts. Catalytic materials are those solids that allow the chemical reaction to occur efficiently and cost-effectively. This book provides you with all necessary information to synthesize, characterize, and relate the properties of a catalyst to its behavior, enabling you to select the appropriate catalyst for the process and reactor system. Oxides (used both as catalysts and as supports for cata

  2. Surface oxygen exchange properties of bismuth oxide-based solid electrolytes and electrode materials

    NARCIS (Netherlands)

    Boukamp, Bernard A.; Vinke, I.C.; de Vries, K.J.; Burggraaf, A.J.

    1989-01-01

    The surface oxygen exchange coefficient, ks, has been measured for the solid solution (Bi2O3)0.75(Er2O3)0.25 and (Bi2O3)0.6(Tb2O3)0.4 (abbreviated BE25 and BT40), using gas-phase 18O exchange techniques. The activation enth alpy of ks amounts to ΔE=110 kJ/molforBT40 andΔE=130 kJ/molforBE25. The

  3. Interactive computer graphic surface modeling of three-dimensional solid domains for boundary element analysis

    Science.gov (United States)

    Perucchio, R.; Ingraffea, A. R.

    1984-01-01

    The establishment of the boundary element method (BEM) as a valid tool for solving problems in structural mechanics and in other fields of applied physics is discussed. The development of an integrated interactive computer graphic system for the application of the BEM to three dimensional problems in elastostatics is described. The integration of interactive computer graphic techniques and the BEM takes place at the preprocessing and postprocessing stages of the analysis process, when, respectively, the data base is generated and the results are interpreted. The interactive computer graphic modeling techniques used for generating and discretizing the boundary surfaces of a solid domain are outlined.

  4. An all-atom simulation study of the ordering of liquid squalane near a solid surface

    Science.gov (United States)

    Tsige, Mesfin; Patnaik, Soumya S.

    2008-05-01

    An all-atom molecular dynamics study using the OPLS force field has been carried out to obtain new insights in to the orientation and ordering of liquid squalane near a solid surface. As observed in previous experiments, the squalane molecules closest to a SiO 2 substrate are found to be tightly bound with their molecular axis preferentially parallel to the interface. Unlike linear alkanes, the squalane molecules are also found to lie preferentially parallel to the liquid/vapor interface. The simulation results predict that the molecular plane orientation of the squalane molecules changes from mainly parallel to perpendicular to the substrate in going further away from the substrate.

  5. Development of breathable hydrophobic/hydrophilic functional textiles

    NARCIS (Netherlands)

    Agrawal, P. (Pramod); Brink, G.J. (Ger)

    2013-01-01

    The proposed bi-functional protective structure intended to have hydrophilic interior towards the skin surface and hydrophobic exterior for protection, ensuring fast transfer of moisture between body and external environment. The sandwich structure is prepared using 100% wool jersey and varieties of

  6. Surface Sensing for Paenibacillus sp. NAIST15-1 Flagellar Gene Expression on Solid Medium.

    Science.gov (United States)

    Kobayashi, Kazuo; Kanesaki, Yu; Yoshikawa, Hirofumi

    2017-08-01

    A rhizosphere Gram-positive bacterial isolate, Paenibacillus sp. NAIST15-1, exhibits intriguing motility behavior on hard agar medium. Paenibacillus sp. shows increased transcription of flagellar genes and hyperflagellation when transferred from liquid to solid medium. Hyperflagellated cells form wandering colonies that are capable of moving around on the surface of medium containing ≥1.5% agar. Transposon mutagenesis was used to identify genes critical for motility. In addition to flagellar genes, this mutagenesis identified five nonflagellar structural genes that were important for motility. Of these, the disruption of degSU, wsfP, or PBN151_4312 resulted in a complete loss of flagellin synthesis. Analysis of flagellar gene promoter activity showed that each mutation severely reduced flagellar gene transcription in a different manner. Flagellar gene transcription was induced in liquid medium by the addition of a viscous agent, Ficoll, or by disruption of flagellar stator genes, indicating that flagellar gene transcription was induced in response to restriction of flagellar rotation. Overexpression of DegSU bypassed the requirement of flagellar rotation restriction for induction of flagellar genes. These results indicate that physical restriction of flagellar rotation by physical contact with the surface of solid medium induces flagellar gene transcription through the activation of DegSU. Further analysis revealed that the same mechanism was conserved in Bacillus subtilis These results demonstrate that flagella act as mechanosensors to control flagellar transcription in Gram-positive bacteria.IMPORTANCE Many bacteria exist on living or nonliving surfaces in nature. Bacteria express distinct behaviors, such as surface motility and biofilm formation, to adapt to surfaces. However, it remains largely unknown how bacteria sense the surfaces on which they sit and how they induce the genes needed for growth on a surface. Swarming motility is flagellum

  7. The Chemistry of Inorganic Precursors during the Chemical Deposition of Films on Solid Surfaces.

    Science.gov (United States)

    Barry, Seán T; Teplyakov, Andrew V; Zaera, Francisco

    2018-02-28

    The deposition of thin solid films is central to many industrial applications, and chemical vapor deposition (CVD) methods are particularly useful for this task. For one, the isotropic nature of the adsorption of chemical species affords even coverages on surfaces with rough topographies, an increasingly common requirement in microelectronics. Furthermore, by splitting the overall film-depositing reactions into two or more complementary and self-limiting steps, as it is done in atomic layer depositions (ALD), film thicknesses can be controlled down to the sub-monolayer level. Thanks to the availability of a vast array of inorganic and metalorganic precursors, CVD and ALD are quite versatile and can be engineered to deposit virtually any type of solid material. On the negative side, the surface chemistry that takes place in these processes is often complex, and can include undesirable side reactions leading to the incorporation of impurities in the growing films. Appropriate precursors and deposition conditions need to be chosen to minimize these problems, and that requires a proper understanding of the underlying surface chemistry. The precursors for CVD and ALD are often designed and chosen based on their known thermal chemistry from inorganic chemistry studies, taking advantage of the vast knowledge developed in that field over the years. Although a good first approximation, however, this approach can lead to wrong choices, because the reactions of these precursors at gas-solid interfaces can be quite different from what is seen in solution. For one, solvents often aid in the displacement of ligands in metalorganic compounds, providing the right dielectric environment, temporarily coordinating to the metal, or facilitating multiple ligand-complex interactions to increase reaction probabilities; these options are not available in the gas-solid reactions associated with CVD and ALD. Moreover, solid surfaces act as unique "ligands", if these reactions are to be

  8. Quasistatic problems for piecewise-continuously growing solids with integral force conditions on surfaces expanding due to additional material influx

    Science.gov (United States)

    Parshin, D. A.; Manzhirov, A. V.

    2017-12-01

    The piecewise continuous processes of additive forming of solids are studied. The being formed solids exhibit properties of deformation heredity and aging. The approaches of linear mechanics of growing solids in the framework of the theory of viscoelasticity of the homogeneously aging isotropic media are applied. Nonclassical boundary-value problems for describing the mentioned processes with the integral satisfaction of force conditions on some expanding due to the influx of additional material parts of the formed solid surface are investigated. A proposition about the commutativity of the time-derived integral operator of viscoelasticity with a limit depending on the solid point with the integration over an arbitrary, expanding due to the growth, surface inside or on the boundary of the growing solid is given. This proposition provides a way to construct the solution of the corresponding growing solids mechanics problem on the basis of Saint-Venant principle. The solution will retrace the evolution of the stress-strain state of the solid under consideration during and after the process of its additive formation. An example of applying the announced technic to modelling the processes of additive forming solids of conical shape under simultaneous action of end loads that are statically equivalent to an axial time-varying force is demonstrated.

  9. Hydrogen Peroxide Sensing Based on Inner Surfaces Modification of Solid-State Nanopore

    Science.gov (United States)

    Zhu, Libo; Gu, Dejian; Liu, Quanjun

    2017-06-01

    There are many techniques for the detection of molecules. But detection of molecules through solid-state nanopore in a solution is one of the promising, high-throughput, and low-cost technology used these days. In the present investigation, a solid-state nanopore platform was fabricated for the detection of hydrogen peroxide (H2O2), which is not only a label free product but also a significant participant in the redox reaction. We have successfully fabricated silicon nitride (Si3N4) nanopores with diameters of 50 nm by using a focused Ga ion beam, the inner surface of the nanopore has been modified with horseradish peroxidase (HRP) by employing carbodiimide coupling chemistry. The immobilized HRP enzymes have ability to induce redox reactions in a single nanopore channel. Moreover, a real-time single aggregated ABTS•+ molecular translocation events were monitored and investigated. The designed solid-state nanopore biosensor is reversible and can be applied to detect H2O2 multiple times.

  10. Correlating the interface resistance and surface adhesion of the Li metal-solid electrolyte interface

    Science.gov (United States)

    Wang, Michael; Sakamoto, Jeff

    2018-02-01

    Solid electrolytes could enable stable cycling of metallic Li anodes, which can offer drastic increases to the capacity of Li-ion batteries. However, little is known about the mechanics of the Li-solid electrolyte interface. This study combines electrochemical and mechanical characterization to correlate interface kinetics with adhesive strength. Cubic garnet with the Li6·25Al0·25La3Zr2O12 (LLZO) formulation was selected as a model solid electrolyte based on its high conductivity and stability against Li metal. Symmetric Li-LLZO cells were tested using electrochemical impedance spectroscopy to determine the interfacial resistance, Rint, and the adhesive strength of the Li-LLZO interface, σadh, was measured using a unique tensile test in an inert atmosphere. It was determined that the Rint is directly correlated to the adhesive strength of Li on LLZO. At the highest Rint in this study, 330 k·cm2 the σadh was 1.1 kPa and at the lowest Rint in this study, 7 ·cm2, σadh was 8 MPa. Furthermore, by optimizing the surface chemistry the wettability of LLZO was enhanced resulting in σadh exceeding the ultimate tensile strength of Li metal. The relationship demonstrated provides a deeper understanding of the mechanical properties of the Li-electrolyte interface, which will play an important role in the design of batteries employing metallic Li anodes.

  11. Hydrophilization of graphite using plasma above/in a solution

    Science.gov (United States)

    Hoshino, Shuhei; Kawahara, Kazuma; Takeuchi, Nozomi

    2018-01-01

    A hydrophilization method for graphite is required for applications such as conductive ink. In typical chemical oxidation methods for graphite have the problems of producing many defects in graphite and a large environmental impact. In recent years, the plasma treatment has attracted attention because of the high quality of the treated samples and the low environmental impact. In this study, we proposed an above-solution plasma treatment with a high contact probability of graphite and plasma since graphite accumulates on the solution surface due to its hydrophobicity, which we compared with a so-called solution plasma treatment. Graphite was hydrophilized via reactions with OH radicals generated by the plasma. It was confirmed that hydroxyl and carboxyl groups were modified to the graphite and the dispersibility was improved. The above-solution plasma achieved more energy-efficient hydrophilization than the solution plasma and it was possible to enhance the dispersibility by increasing the plasma–solution contact area.

  12. Impact of Different Surface Ligands on the Optical Properties of PbS Quantum Dot Solids.

    Science.gov (United States)

    Xu, Fan; Gerlein, Luis Felipe; Ma, Xin; Haughn, Chelsea R; Doty, Matthew F; Cloutier, Sylvain G

    2015-04-21

    The engineering of quantum dot solids with low defect concentrations and efficient carrier transport through a ligand strategy is crucial to achieve efficient quantum dot (QD) optoelectronic devices. Here, we study the consequences of various surface ligand treatments on the light emission properties of PbS quantum dot films using 1,3-benzenedithiol (1,3-BDT), 1,2-ethanedithiol (EDT), mercaptocarboxylic acids (MPA) and ammonium sulfide ((NH4)2S). We first investigate the influence of different ligand treatments on the inter-dot separation, which mainly determines the conductivity of the QD films. Then, through a combination of photoluminescence and transient photoluminescence characterization, we demonstrate that the radiative and non-radiative recombination mechanisms in the quantum dot films depend critically on the length and chemical structure of the surface ligands.

  13. Impact of Different Surface Ligands on the Optical Properties of PbS Quantum Dot Solids

    Directory of Open Access Journals (Sweden)

    Fan Xu

    2015-04-01

    Full Text Available The engineering of quantum dot solids with low defect concentrations and efficient carrier transport through a ligand strategy is crucial to achieve efficient quantum dot (QD optoelectronic devices. Here, we study the consequences of various surface ligand treatments on the light emission properties of PbS quantum dot films using 1,3-benzenedithiol (1,3-BDT, 1,2-ethanedithiol (EDT, mercaptocarboxylic acids (MPA and ammonium sulfide ((NH42S. We first investigate the influence of different ligand treatments on the inter-dot separation, which mainly determines the conductivity of the QD films. Then, through a combination of photoluminescence and transient photoluminescence characterization, we demonstrate that the radiative and non-radiative recombination mechanisms in the quantum dot films depend critically on the length and chemical structure of the surface ligands.

  14. RX J1856.5-3754: A Strange Star with Solid Quark Surface?

    Science.gov (United States)

    Zhang, Xiaoling; Xu, Renxin; Zhang, Shuangnan

    2003-01-01

    The featureless spectra of isolated 'neutron stars' may indicate that they are actually bare strange stars but a definitive conclusion on the nature of the compact objects cannot be reached until accurate and theoretically calculated spectra of the bare quark surface are known. However due to the complex nonlinearity of quantum chromodynamics it is almost impossible to present a definitive and accurate calculation of the density-dominated quark-gluon plasma from the first principles. Nevertheless it was suggested that cold quark matter with extremely high baryon density could be in a solid state. Within the realms of this possibility we have fitted the 500ks Chandra LETG/HRC data for the brightest isolated neutron star RX 51856.5-3754 with a phenomenological spectral model and found that electric conductivity of quark matter on the stellar surface is about 1.5 x 10(exp 16)/s.

  15. Elastic waves at periodically-structured surfaces and interfaces of solids

    Directory of Open Access Journals (Sweden)

    A. G. Every

    2014-12-01

    Full Text Available This paper presents a simple treatment of elastic wave scattering at periodically structured surfaces and interfaces of solids, and the existence and nature of surface acoustic waves (SAW and interfacial (IW waves at such structures. Our treatment is embodied in phenomenological models in which the periodicity resides in the boundary conditions. These yield zone folding and band gaps at the boundary of, and within the Brillouin zone. Above the transverse bulk wave threshold, there occur leaky or pseudo-SAW and pseudo-IW, which are attenuated via radiation into the bulk wave continuum. These have a pronounced effect on the transmission and reflection of bulk waves. We provide examples of pseudo-SAW and pseudo-IW for which the coupling to the bulk wave continuum vanishes at isloated points in the dispersion relation. These supersonic guided waves correspond to embedded discrete eigenvalues within a radiation continuum. We stress the generality of the phenomena that are exhibited at widely different scales of length and frequency, and their relevance to situations as diverse as the guiding of seismic waves in mine stopes, the metrology of periodic metal interconnect structures in the semiconductor industry, and elastic wave scattering by an array of coplanar cracks in a solid.

  16. Study on the surface electronic properties of Li-containing solids

    Energy Technology Data Exchange (ETDEWEB)

    Matsuura, Fumio; Suzuki, Atsushi; Yamaguchi, Kenji; Yamawaki, M. [Tokyo Univ. (Japan)

    1998-03-01

    The electronic state of Li{sub 2}O surface will be modified by absorption and/or desorption of chemically-active species, such as H{sub 2} and H{sub 2}O. The reactions induced by these species will involve some point defects in the solid. Whereas the high temperature Kelvin probe has proven to be quite effective in obtaining information on the surface reactions between gas and solid, an attempt is being made to incorporate numerical calculation to obtain further information which may not be easily done by experiments. The code employed in the present study is `CRYSTAL`, which employs a self-consistent-field Hartree-Fock method. As a preliminary study, we tried to calculate the change of Fermi Energy as a function of the density of oxygen vacancy. The results revealed that the greater the density of oxygen vacancy, the larger the Fermi Energy of Li{sub 2}O, which was consistent with the experimental results obtained by high temperature Kelvin probe. (author)

  17. Large apparent electric size of solid-state nanopores due to spatially extended surface conduction.

    Science.gov (United States)

    Lee, Choongyeop; Joly, Laurent; Siria, Alessandro; Biance, Anne-Laure; Fulcrand, Rémy; Bocquet, Lydéric

    2012-08-08

    Ion transport through nanopores drilled in thin membranes is central to numerous applications, including biosensing and ion selective membranes. This paper reports experiments, numerical calculations, and theoretical predictions demonstrating an unexpectedly large ionic conduction in solid-state nanopores, taking its origin in anomalous entrance effects. In contrast to naive expectations based on analogies with electric circuits, the surface conductance inside the nanopore is shown to perturb the three-dimensional electric current streamlines far outside the nanopore in order to meet charge conservation at the pore entrance. This unexpected contribution to the ionic conductance can be interpreted in terms of an apparent electric size of the solid-state nanopore, which is much larger than its geometric counterpart whenever the number of charges carried by the nanopore surface exceeds its bulk counterpart. This apparent electric size, which can reach hundreds of nanometers, can have a major impact on the electrical detection of translocation events through nanopores, as well as for ionic transport in biological nanopores.

  18. Search for Hydrophilic Marine Fungal Metabolites: A Rational Approach for Their Production and Extraction in a Bioactivity Screening Context

    Directory of Open Access Journals (Sweden)

    Jean-François Biard

    2011-01-01

    Full Text Available In the search for bioactive natural products, our lab screens hydrophobic extracts from marine fungal strains. While hydrophilic active substances were recently identified from marine macro-organisms, there was a lack of reported metabolites in the marine fungi area. As such, we decided to develop a general procedure for screening of hydrophobic metabolites. The aim of this study was to compare different processes of fermentation and extraction, using six representative marine fungal strains, in order to define the optimized method for production. The parameters studied were (a which polar solvent to select, (b which fermentation method to choose between solid and liquid cultures, (c which raw material, the mycelium or its medium, to extract and (d which extraction process to apply. The biochemical analysis and biological evaluations of obtained extracts led to the conclusion that the culture of marine fungi by agar surface fermentation followed by the separate extraction of the mycelium and its medium by a cryo-crushing and an enzymatic digestion with agarase, respectively, was the best procedure when screening for hydrophilic bioactive metabolites. During this development, several bioactivities were detected, confirming the potential of hydrophilic crude extracts in the search for bioactive natural products.

  19. Uptake Coefficients of NO3 Radicals on Solid Surfaces of Sea-Salts

    Science.gov (United States)

    Gratpanche, F.; Sawerysyn, J.-P.

    1999-02-01

    Uptake coefficients of nitrate radicals (γ NO_3) have been measured by a technique involving a coated-wall flow tube with radical detection by E.P.R. spectrometry. The variation of NO3 concentration in the gas phase was followed indirectly by monitoring OH radicals produced by the titration reaction H + NO_3. The mean initial value of γ NO3 measured on solid NaCl surfaces was (1.7± 1.2)× 10-2) in the temperature range 258-301 K, while for solid NaBr surfaces the value was (0.11 ± 0.06) at 293 K. In each case, errors limits correspond to one standard deviation. For NaBr, a slight negative temperature dependence was observed over the investigated range, 243-293 K, which can be represented by γ_NO_3^NaBr = 1.6 ≤ft(begin{array}{l}+1.8 -0.9) × 10-3exp [(1210± 200)/T]. An analysis of the results shows that under some conditions the heterogeneous loss of nitrate radicals on sea-salt aerosol particles at ambient temperature could be competitive with their loss by homogeneous reaction in the marine troposphere at night. Les coefficients de capture des radicaux nitrate (γ NO_3) sur des surfaces de sels marins (NaCl et NaBr) ont été mesurés aux températures troposphériques en utilisant la technique du réacteur à écoulement à paroi recouverte couplée à un spectromètre de résonance paramagnétique électronique (R.P.E). La variation de la concentration en phase gazeuse des radicaux nitrate en présence des surfaces étudiées est suivie en mesurant le signal R.P.E des radicaux OH produits par la réaction de titrage H + NO3. Pour des températures comprises entre 258 et 301 K, la valeur moyenne du coefficient de capture initial (γ NO_3) sur des surfaces solides de NaCl est égal à (1.7± 1.2)× 10-2). Sur des surfaces solides de NaBr, (γ NO_3) est égal à (0.11 ± 0.06) à 293 K. L'incertitude correspond à une déviation standard. Par ailleurs, pour ce type de surfaces, une légère dépendance négative avec la température est observée dans la

  20. Surface tension and a self-consistent theory of soft composite solids with elastic inclusions.

    Science.gov (United States)

    Mancarella, Francesco; Wettlaufer, John S

    2017-02-07

    The importance of surface tension effects is being recognized in the context of soft composite solids, where they are found to significantly affect the mechanical properties, such as the elastic response to an external stress. It has recently been discovered that Eshelby's inclusion theory breaks down when the inclusion size approaches the elastocapillary length L≡γ/E, where γ is the inclusion/host surface tension and E is the host Young's modulus. Extending our recent results for liquid inclusions, here we model the elastic behavior of a non-dilute distribution of isotropic elastic spherical inclusions in a soft isotropic elastic matrix, subject to a prescribed infinitesimal far-field loading. Within our framework, the composite stiffness is uniquely determined by the elastocapillary length L, the spherical inclusion radius R, and the stiffness contrast parameter C, which is the ratio of the inclusion to the matrix stiffness. We compare the results with those from the case of liquid inclusions, and we derive an analytical expression for elastic cloaking of the composite by the inclusions. Remarkably, we find that the composite stiffness is influenced significantly by surface tension even for inclusions two orders of magnitude more stiff than the host matrix. Finally, we show how to simultaneously determine the surface tension and the inclusion stiffness using two independent constraints provided by global and local measurements.

  1. Tunneling Rate Constants for H2CO+H on Amorphous Solid Water Surfaces

    Science.gov (United States)

    Song, Lei; Kästner, Johannes

    2017-12-01

    Formaldehyde (H2CO) is one of the most abundant molecules observed in the icy mantle covering interstellar grains. Studying its evolution can contribute to our understanding of the formation of complex organic molecules in various interstellar environments. In this work, we investigated the hydrogenation reactions of H2CO yielding CH3O, CH2OH, and the hydrogen abstraction resulting in H2+HCO on an amorphous solid water (ASW) surface using a quantum mechanics/molecular mechanics (QM/MM) model. The binding energies of H2CO on the ASW surface vary broadly, from 1000 to 9370 K. No correlation was found between binding energies and activation energies of hydrogenation reactions. Combining instanton theory with QM/MM modeling, we calculated rate constants for the Langmuir–Hinshelwood and the Eley–Rideal mechanisms for the three product channels of H+H2CO surface reactions down to 59 K. We found that the channel producing CH2OH can be ignored, owing to its high activation barrier leading to significantly lower rates than the other two channels. The ASW surface influences the reactivity in favor of formation of CH3O (branching ratio ∼80%) and hinders the H2CO dissociation into H2+HCO. In addition, kinetic isotope effects are strong in all reaction channels and vary strongly between the channels. Finally, we provide fits of the rate constants to be used in astrochemical models.

  2. Interpretation of contact angle measurements on two different fluoropolymers for the determination of solid surface tension.

    Science.gov (United States)

    Tavana, H; Simon, F; Grundke, K; Kwok, D Y; Hair, M L; Neumann, A W

    2005-11-15

    Contact angle measurements with a large number of liquids on the semi-fluorinated acryl polymer EGC-1700 films are reported. The surface tension was determined to be gammasv=13.84 mJ/m2 from contact angles of octamethylcyclotetrasiloxane (OMCTS) and decamethylcyclopentasiloxane (DMCPS). Inertness of these two liquids makes them ideal for determination of surface tension of low-energy fluoropolymers. On the other hand, contact angles of many other liquids deviated somewhat from a smooth contact angle pattern that represents the EGC-1700 surface tension. It is argued that noninertness of the molecules of these liquids gives rise to specific interactions with the polymer film, causing the deviations. Furthermore, contact angles of a series of n-alkanes (n-hexane to n-hexadecane) showed systematic deviations from this curve, similar to the trend observed for n-alkanes/Teflon AF 1600 systems studied earlier. Adsorption of vapor of short-chain liquids onto the polymer film caused their contact angles to fall above the gammasv=13.84 mJ/m2 curve, and a parallel alignment of molecules of the long-chain n-alkanes in the vicinity of the solid was the explanation for the deviation of their contact angles below it. It is found that vapor adsorption effect is more significant in the case of Teflon AF 1600, while the alignment of liquid molecules close to the surface is more pronounced for EGC-1700.

  3. Membrane Distillation of Meat Industry Effluent with Hydrophilic Polyurethane Coated Polytetrafluoroethylene Membranes

    Science.gov (United States)

    Mostafa, M. G.; Zhu, Bo; Cran, Marlene; Dow, Noel; Milne, Nicholas; Desai, Dilip

    2017-01-01

    Meat rendering operations produce stick water waste which is rich in proteins, fats, and minerals. Membrane distillation (MD) may further recover water and valuable solids, but hydrophobic membranes are contaminated by the fats. Here, commercial hydrophobic polytetrafluorethylene (PTFE) membranes with a hydrophilic polyurethane surface layer (PU-PTFE) are used for the first time for direct contact MD (DCMD) on real poultry, fish, and bovine stick waters. Metal membrane microfiltration (MMF) was also used to capture fats prior to MD. Although the standard hydrophobic PTFE membranes failed rapidly, PU-PTFE membranes effectively processed all stick water samples to colourless permeate with sodium rejections >99%. Initial clean solution fluxes 5–6 L/m2/h declined to less than half during short 40% water recovery tests for all stick water samples. Fish stick water uniquely showed reduced fouling and up to 78% water recovery. Lost flux was easily restored by rinsing the membrane with clean water. MMF prior to MD removed 92% of fats, facilitating superior MD performance. Differences in fouling between stick waters were attributed to temperature polarisation from higher melt temperature fats and relative proportions to proteins. Hydrophilic coated MD membranes are applicable to stick water processing but further studies should consider membrane cleaning and longer-term stability. PMID:28961203

  4. Hydrophilic nano-silica coating agents with platinum and diamond nanoparticles for denture base materials.

    Science.gov (United States)

    Yoshizaki, Taro; Akiba, Norihisa; Inokoshi, Masanao; Shimada, Masayuki; Minakuchi, Shunsuke

    2017-05-31

    Preventing microorganisms from adhering to the denture surface is important for ensuring the systemic health of elderly denture wearers. Silica coating agents provide high hydrophilicity but lack durability. This study investigated solutions to improve the durability of the coating layer, determine an appropriate solid content concentration of SiO 2 in the silica coating agent, and evaluate the effect of adding platinum (Pt) and diamond nanoparticles (ND) to the agent. Five coating agents were prepared with different SiO 2 concentrations with/without Pt and ND additives. The contact angle was measured, and the brush-wear test was performed. Scanning electron microscopy was used to investigate the silica coating layer. The appropriate concentration of SiO 2 was found to be 0.5-0.75 wt%. The coating agents with additives showed significantly high hydrophilicity immediately after coating and after the brush-wear test. The coating agents with/without additives formed a durable coating layer even after the brush-wear test.

  5. Membrane Distillation of Meat Industry Effluent with Hydrophilic Polyurethane Coated Polytetrafluoroethylene Membranes.

    Science.gov (United States)

    Mostafa, M G; Zhu, Bo; Cran, Marlene; Dow, Noel; Milne, Nicholas; Desai, Dilip; Duke, Mikel

    2017-09-29

    Meat rendering operations produce stick water waste which is rich in proteins, fats, and minerals. Membrane distillation (MD) may further recover water and valuable solids, but hydrophobic membranes are contaminated by the fats. Here, commercial hydrophobic polytetrafluorethylene (PTFE) membranes with a hydrophilic polyurethane surface layer (PU-PTFE) are used for the first time for direct contact MD (DCMD) on real poultry, fish, and bovine stick waters. Metal membrane microfiltration (MMF) was also used to capture fats prior to MD. Although the standard hydrophobic PTFE membranes failed rapidly, PU-PTFE membranes effectively processed all stick water samples to colourless permeate with sodium rejections >99%. Initial clean solution fluxes 5-6 L/m²/h declined to less than half during short 40% water recovery tests for all stick water samples. Fish stick water uniquely showed reduced fouling and up to 78% water recovery. Lost flux was easily restored by rinsing the membrane with clean water. MMF prior to MD removed 92% of fats, facilitating superior MD performance. Differences in fouling between stick waters were attributed to temperature polarisation from higher melt temperature fats and relative proportions to proteins. Hydrophilic coated MD membranes are applicable to stick water processing but further studies should consider membrane cleaning and longer-term stability.

  6. Membrane Distillation of Meat Industry Effluent with Hydrophilic Polyurethane Coated Polytetrafluoroethylene Membranes

    Directory of Open Access Journals (Sweden)

    M. G. Mostafa

    2017-09-01

    Full Text Available Meat rendering operations produce stick water waste which is rich in proteins, fats, and minerals. Membrane distillation (MD may further recover water and valuable solids, but hydrophobic membranes are contaminated by the fats. Here, commercial hydrophobic polytetrafluorethylene (PTFE membranes with a hydrophilic polyurethane surface layer (PU-PTFE are used for the first time for direct contact MD (DCMD on real poultry, fish, and bovine stick waters. Metal membrane microfiltration (MMF was also used to capture fats prior to MD. Although the standard hydrophobic PTFE membranes failed rapidly, PU-PTFE membranes effectively processed all stick water samples to colourless permeate with sodium rejections >99%. Initial clean solution fluxes 5–6 L/m2/h declined to less than half during short 40% water recovery tests for all stick water samples. Fish stick water uniquely showed reduced fouling and up to 78% water recovery. Lost flux was easily restored by rinsing the membrane with clean water. MMF prior to MD removed 92% of fats, facilitating superior MD performance. Differences in fouling between stick waters were attributed to temperature polarisation from higher melt temperature fats and relative proportions to proteins. Hydrophilic coated MD membranes are applicable to stick water processing but further studies should consider membrane cleaning and longer-term stability.

  7. Adsorption of phenol molecules by sodium dodecyl sulfate (SDS) surfactants deposited on solid surfaces: A computer simulation study.

    Science.gov (United States)

    Peredo-Mancilla, Deneb; Dominguez, Hector

    2016-04-01

    Adsorption studies of phenol molecules on a sodium dodecyl sulfate (SDS) micelle were investigated by molecular dynamics simulations. Simulations were carried out in bulk and on three distinct solid surfaces, silicon dioxide, titanium dioxide and graphite. It was observed that different surfactant micellar shapes were formed on the surfaces. For the silicon dioxide and titanium dioxide surfaces the surfactants were adsorbed by their headgroups whereas for the graphite surface they were adsorbed mainly by their tail groups. It was found that the amount of phenol adsorbed on the SDS micelle was altered by the surfactant shape deposited on the solid surface. However, the best phenol adsorption was obtained by the surfactant modified silicon dioxide surface. Moreover, in all cases, from structural investigations, it was determined that the phenol molecules were located inside the surfactant micelle with their hydroxyl groups close to the SDS headgroups. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. 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.

  9. Surface hydrodynamics of viscoelastic fluids and soft solids: Surfing bulk rheology on capillary and Rayleigh waves.

    Science.gov (United States)

    Monroy, Francisco

    2017-09-01

    From the recent advent of the new soft-micro technologies, the hydrodynamic theory of surface modes propagating on viscoelastic bodies has reinvigorated this field of technology with interesting predictions and new possible applications, so recovering its scientific interest very limited at birth to the academic scope. Today, a myriad of soft small objects, deformable meso- and micro-structures, and macroscopically viscoelastic bodies fabricated from colloids and polymers are already available in the materials catalogue. Thus, one can envisage a constellation of new soft objects fabricated by-design with a functional dynamics based on the mechanical interplay of the viscoelastic material with the medium through their interfaces. In this review, we recapitulate the field from its birth and theoretical foundation in the latest 1980s up today, through its flourishing in the 90s from the prediction of extraordinary Rayleigh modes in coexistence with ordinary capillary waves on the surface of viscoelastic fluids, a fact first confirmed in experiments by Dominique Langevin and me with soft gels [Monroy and Langevin, Phys. Rev. Lett. 81, 3167 (1998)]. With this observational discovery at sight, we not only settled the theory previously formulated a few years before, but mainly opened a new field of applications with soft materials where the mechanical interplay between surface and bulk motions matters. Also, new unpublished results from surface wave experiments performed with soft colloids are reported in this contribution, in which the analytic methods of wave surfing synthetized together with the concept of coexisting capillary-shear modes are claimed as an integrated tool to insightfully scrutinize the bulk rheology of soft solids and viscoelastic fluids. This dedicatory to the figure of Dominique Langevin includes an appraisal of the relevant theoretical aspects of the surface hydrodynamics of viscoelastic fluids, and the coverage of the most important experimental

  10. Formation of Reversible Solid Electrolyte Interface on Graphite Surface from Concentrated Electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Dongping; Tao, Jinhui; Yan, Pengfei; Henderson, Wesley A.; Li, Qiuyan; Shao, Yuyan; Helm, Monte L.; Borodin, Oleg; Graff, Gordon L.; Polzin, Bryant; Wang, Chong-Min; Engelhard, Mark; Zhang, Ji-Guang; De Yoreo, James J.; Liu, Jun; Xiao, Jie

    2017-02-10

    Interfacial phenomena have always been key determinants for the performance of energy storage technologies. The solid electrolyte interfacial (SEI) layer, pervasive on the surfaces of battery electrodes for numerous chemical couples, directly affects the ion transport, charge transfer and lifespan of the entire energy system. Almost all SEI layers, however, are unstable resulting in the continuous consumption of the electrolyte. Typically, this leads to the accumulation of degradation products on/restructuring of the electrode surface and thus increased cell impedance, which largely limits the long-term operation of the electrochemical reactions. Herein, a completely new SEI formation mechanism has been discovered, in which the electrolyte components reversibly self-assemble into a protective surface coating on a graphite electrode upon changing the potential. In contrast to the established wisdom regarding the necessity of employing the solvent ethylene carbonate (EC) to form a protective SEI layer on graphite, a wide range of EC-free electrolytes are demonstrated for the reversible intercalation/deintercalation of Li+ cations within a graphite lattice, thereby providing tremendous flexibility in electrolyte tailoring for battery couples. This novel finding is broadly applicable and provides guidance for how to control interfacial reactions through the relationship between ion aggregation and solvent decomposition at polarized interfaces.

  11. Solid-state 17O NMR study of benzoic acid adsorption on metal oxide surfaces.

    Science.gov (United States)

    Hagaman, Edward W; Chen, Banghao; Jiao, Jian; Parsons, William

    2012-02-01

    Solid-state (17)O NMR spectra of (17)O-labeled benzoic and anisic acids are reported and benzoic acid is used to probe the surface of metal oxides. Complexes formed when benzoic acid is dry mixed with mesoporous silica, and nonporous titania and alumina are characterized. Chemical reactions with silica are not observed. The nature of benzoic acid on silica is a function of the water content of the oxide. The acid disperses in the pores of the silica if the silica is in equilibrium with ambient laboratory humidity. The acid displays high mobility as evidenced by a liquid-like, Lorentzian resonance. Excess benzoic acid remains as the crystalline hydrogen-bonded dimer. Benzoic acid reacts with titania and alumina surfaces in equilibrium with laboratory air to form the corresponding titanium and aluminum benzoates. In both materials the oxygen of the (17)O-labeled acid is bound to the metal, showing the reaction proceeds by bond formation between oxygen deficient metal sites and the oxygen of the carboxylic acid. (27)Al MAS NMR confirms this mechanism for the reaction on alumina. Dry mixing of benzoic acid with alumina rapidly quenches pentacoordinate aluminum sites, excellent evidence that these sites are confined to the surface of the alumina particles. Copyright © 2011 Elsevier Inc. All rights reserved.

  12. Response surface methodology for optimization of production of lovastatin by solid state fermentation

    Directory of Open Access Journals (Sweden)

    Ruchir C. Pansuriya

    2010-03-01

    Full Text Available Lovastatin, an inhibitor of HMG-CoA reductase, was produced by solid state fermentation (SSF using a strain of Aspergillus terreus UV 1718. Different solid substrates and various combinations thereof were evaluated for lovastatin production. Wheat bran supported the maximum production (1458 ± 46 µg g-1 DFM of lovastatin. Response surface methodology (RSM was applied to optimize the medium constituents. A 2(4 full-factorial central composite design (CCD was chosen to explain the combined effects of the four medium constituents, viz. moisture content, particle size of the substrate, di-potassium hydrogen phosphate and trace ion solution concentration. Maximum lovastatin production of 2969 µg g-1 DFM was predicted by the quadratic model which was verified experimentally to be 3004 ± 25 µg g-1 DFM. Further RSM optimized medium supplemented with mycological, peptone supported highest yield of 3723.4±49 µg g-1 DFM. Yield of lovastatin increased 2.6 fold as with compared to un-optimized media.

  13. Hydrogen-deuterium substitution in solid ethanol by surface reactions at low temperatures

    Science.gov (United States)

    Oba, Yasuhiro; Osaka, Kazuya; Chigai, Takeshi; Kouchi, Akira; Watanabe, Naoki

    2016-10-01

    Ethanol (CH3CH2OH) is one of the most abundant complex organic molecules in star-forming regions. Despite its detection in the gas phase only, ethanol is believed to be formed by low-temperature grain-surface reactions. Methanol, the simplest alcohol, has been a target for observational, experimental, and theoretical studies in view of its deuterium enrichment in the interstellar medium; however, the deuterium chemistry of ethanol has not yet been an area of focus. Recently, deuterated dimethyl ether, a structural isomer of ethanol, was found in star-forming regions, indicating that deuterated ethanol can also be present in those environments. In this study, we performed laboratory experiments on the deuterium fractionation of solid ethanol at low temperatures through a reaction with deuterium (D) atoms at 10 K. Hydrogen (H)-D substitution, which increases the deuteration level, was found to occur on the ethyl group but not on the hydroxyl group. In addition, when deuterated ethanol (e.g. CD3CD2OD) solid was exposed to H atoms at 10 K, D-H substitution that reduced the deuteration level occurred on the ethyl group. Based on the results, it is likely that deuterated ethanol is present even under H-atom-dominant conditions in the interstellar medium.

  14. Photochemical immobilization of anthraquinone conjugated oligonucleotides and PCR amplicons on solid surfaces

    DEFF Research Database (Denmark)

    Koch, T; Jacobsen, N; Fensholdt, J

    2000-01-01

    Ligand immobilization on solid surfaces is an essential step in fields such as diagnostics, bio sensor manufacturing, and new material sciences in general. In this paper a photochemical approach based on anthraquinone as the chromophore is presented. Photochemical procedures offer special...... advantages as they are able to generate highly reactive species in an orientation specific manner. As presented here, anthraquinone (AQ) mediated covalent DNA immobilization appears to be superior to currently known procedures. A synthetic procedure providing AQ-phosphoramidites is presented. These reagents...... facilitate AQ conjugation during routine DNA synthesis, thus enabling the AQ-oligonucleotides to be immobilized in a very convenient and efficient manner. AQ-conjugated PCR primers can be used directly in PCR. When the PCR is performed in solution, the amplicons can be immobilized after the PCR. Moreover...

  15. Performance of Surface-Mount Ceramic and Solid Tantalum Capacitors for Cryogenic Applications

    Science.gov (United States)

    Patterson, Richard L.; MacDonald, Thomas L.; Hammoud, Ahmad; Gerber, Scott

    1998-01-01

    Low temperature electronics are of great interest for space exploration programs. These include missions to the outer planets, earth-orbiting and deep-space probes, remote-sensing and communication satellites. Terrestrial applications would also benefit from the availability of low temperature electronics. Power components capable of low temperature operation would, thus, enhance the technologies needed for the development of advanced power systems suitable for use in harsh environments. In this work, ceramic and solid tantalum capacitors were evaluated in terms of their dielectric properties as a function of temperature and at various frequencies. The surface-mount devices were characterized in terms of their capacitance stability and dissipation factor in the frequency range of 50 Hz to 100 kHz at temperatures ranging from room temperature (20 deg. C) to about liquid nitrogen temperature (-190 deg. C). The results are discussed and conclusions made concerning the suitability of the capacitors investigated for low temperature applications.

  16. Surface Activity and Bulk Defect Chemistry of Solid Oxide Fuel Cell Cathodes

    Science.gov (United States)

    Usiskin, Robert Ezra

    In the first half of this thesis, a new robotic instrument called a scanning impedance probe is presented that can acquire electrochemical impedance spectra in automated fashion from hundreds of thin film microelectrodes with systematically varied properties. Results from this instrument are presented for three catalyst compositions that are commonly considered for use in state-of-the-art solid oxide fuel cell cathodes. For (La0.8Sr0.2) 0.95MnO3+delta; (LSM), the impedance spectra are well fit by a through-the-film reaction pathway. Transport rates are extracted, and the surface activity towards oxygen reduction is found to be correlated with the number of exposed grain boundary sites, suggesting that grain boundaries are more surface-active than grains. For La0.5Sr0.5CoO 3-delta; (LSC), the surface activity degrades 50x initially and then stabilizes at a comparable activity to that of previously measured Ba 0.5Sr0.5Co0.8Fe0.2O3-delta; films. For Sr0.06Nb0.06Bi1.87O3 (SNB), an example of a doped bismuth oxide, the activity of the metal-SNB boundary is measured. In the second half of this thesis, SrCo0.9Nb0.1O 3-delta; is selected as a case study of perovskites containing Sr and Co, which are the most active oxygen reduction catalysts known. Several bulk properties are measured, and synchrotron data are presented that provide strong evidence of substantial cobalt-oxygen covalency at high temperatures. This covalent bonding may be the underlying source of the high surface activity.

  17. Movement variability and muscle activity relative to center of pressure during unipedal stance on solid and compliant surfaces.

    Science.gov (United States)

    Croft, James L; von Tscharner, Vinzenz; Zernicke, Ronald F

    2008-10-01

    Compliant surfaces are used to challenge postural stability, but assessments are frequently limited to summary measures of center of pressure that do not provide insights into the temporal dynamics of motor coordination. Here, we measured center-of-pressure changes on three surfaces (solid, foam, and air-filled disc) and quantified the relative timing of changes in joint angles and muscle activity with respect to center-of-pressure changes. Nine active male subjects (20-30 years old) performed ten 30-s trials of unipedal stance on each of the three surfaces. Sway range, mean sway, mean sway velocity, path length, and fitted ellipse area increased, monotonically, from solid surface to foam to air-filled disc. The number of significant cross-correlations was greater for the compliant surfaces compared with the solid surface. Muscle activity preceded changes in center-of-pressure displacement, with the type of surface affecting the magnitude of the lead in the mediolateral direction. Center of pressure was more constrained on less stable surfaces and in the mediolateral direction.

  18. Interaction of Solid Lipid Nanoparticles and Specific Proteins of the Corona Studied by Surface Plasmon Resonance

    Directory of Open Access Journals (Sweden)

    Mauricio E. Di Ianni

    2017-01-01

    Full Text Available The applications of pharmaceutical and medical nanosystems are among the most intensively investigated fields in nanotechnology. A relevant point to be considered in the design and development of nanovehicles intended for medical use is the formation of the “protein corona” around the nanoparticle, that is, a complex biomolecular layer formed when the nanovehicle is exposed to biological fluids. The chemical nature of the protein corona determines the biological identity of the nanoparticle and influences, among others, the recognition of the nanocarrier by the mononuclear phagocytic system and, thus, its clearance from the blood. Recent works suggest that Surface Plasmon Resonance (SPR, extensively employed for the analysis of biomolecular interactions, can shed light on the formation of the protein corona and its interaction with the surroundings. The synthesis and characterization of solid lipid nanoparticles (SLN coated with polymers of different chemical nature (e.g., polyvinyl alcohol, chitosans are reported. The proof-of-concept for the use of SPR technique in characterizing protein-nanoparticle interactions of surface-immobilized proteins (immunoglobulin G and bovine serum albumin, both involved in the formation of the corona subjected to flowing SLN is demonstrated for non-chitosan-coated nanoparticles. All assayed nanosystems show more preference for IgG than for BSA, such preference being more pronounced in the case of polyvinyl-alcohol-coated SLN.

  19. Standard test method for damage to contacting solid surfaces under fretting conditions

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This test method covers the studying or ranking the susceptibility of candidate materials to fretting corrosion or fretting wear for the purposes of material selection for applications where fretting corrosion or fretting wear can limit serviceability. 1.2 This test method uses a tribological bench test apparatus with a mechanism or device that will produce the necessary relative motion between a contacting hemispherical rider and a flat counterface. The rider is pressed against the flat counterface with a loading mass. The test method is intended for use in room temperature air, but future editions could include fretting in the presence of lubricants or other environments. 1.3 The purpose of this test method is to rub two solid surfaces together under controlled fretting conditions and to quantify the damage to both surfaces in units of volume loss for the test method. 1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.5...

  20. Effects of viscoelasticity on drop impact and spreading on a solid surface

    Science.gov (United States)

    Izbassarov, Daulet; Muradoglu, Metin

    2016-06-01

    The effects of viscoelasticity on drop impact and spreading on a flat solid surface are studied computationally using a finite-difference-front-tracking method. The finitely extensible nonlinear elastic-Chilcott-Rallison model is used to account for the fluid viscoelasticity. It is found that viscoelasticity favors advancement of contact line during the spreading phase, leading to a slight increase in the maximum spreading, in agreement with experimental observations [Huh, Jung, Seo, and Lee, Microfluid. Nanofluid. 18, 1221 (2015), 10.1007/s10404-014-1518-4]. However, in contrast with the well-known antirebound effects of polymeric additives, the viscoelasticity is found to enhance the tendency of the drop rebound in the receding phase. These results suggest that the antirebound effects are mainly due to the polymer-induced modification of wetting properties of the substrate rather than the change in the material properties of the drop fluid. A model is proposed to test this hypothesis. It is found that the model results in good qualitative agreement with the experimental observations and the antirebound behavior can be captured by the modification of surface wetting properties in the receding phase.

  1. Nanobubbles at Hydrophilic Particle-Water Interfaces.

    Science.gov (United States)

    Pan, Gang; He, Guangzhi; Zhang, Meiyi; Zhou, Qin; Tyliszczak, Tolek; Tai, Renzhong; Guo, Jinghua; Bi, Lei; Wang, Lei; Zhang, Honggang

    2016-11-01

    The puzzling persistence of nanobubbles breaks Laplace's law for bubbles, which is of great interest for promising applications in surface processing, H 2 and CO 2 storage, water treatment, and drug delivery. So far, nanobubbles have mostly been reported on hydrophobic planar substrates with atomic flatness. It remains a challenge to quantify nanobubbles on rough and irregular surfaces because of the lack of a characterization technique that can detect both the nanobubble morphology and chemical composition inside individual nanobubble-like objects. Here, by using synchrotron-based scanning transmission soft X-ray microscopy (STXM) with nanometer resolution, we discern nanoscopic gas bubbles of >25 nm with direct in situ proof of O 2 inside the nanobubbles at a hydrophilic particle-water interface under ambient conditions. We find a stable cloud of O 2 nanobubbles at the diatomite particle-water interface hours after oxygen aeration and temperature variation. The in situ technique may be useful for many surface nanobubble-related studies such as material preparation and property manipulation, phase equilibrium, nucleation kinetics, and relationships with chemical composition within the confined nanoscale space. The oxygen nanobubble clouds may be important in modifying particle-water interfaces and offering breakthrough technologies for oxygen delivery in sediment and/or deep water environments.

  2. Electrochemical control of peptide self-organization on atomically flat solid surfaces: A Case study with Graphite.

    Science.gov (United States)

    Seki, Takakazu; So, Christopher R; Page, Tamon R; Starkebaum, David Alan; Hayamizu, Yuhei; Sarikaya, Mehmet

    2017-10-02

    Nanoscale self-organization of biomolecules, such as proteins and peptides, on solid surfaces under controlled conditions is an important issue to establish functional bio/solid soft interfaces for bioassays, biosensors, and biofuel cells. Electrostatic interaction between proteins and surfaces is one of the most essential parameters in the adsorption and self-assembly of proteins on solid surfaces. Although the adsorption of proteins has been studied with respect to the electrochemical surface potential, the self-assembly of proteins or peptides forming well-organized nanostructures templated by lattice structure of the solid surfaces has not been studied in the relation with the surface potential. In this work, we utilize graphite-binding peptides (GrBPs) selected by phage display method to investigate the relationship between the electrochemical potential of the highly ordered pyrolytic graphite (HOPG) and peptide self-organization forming long-range ordered structures. Under modulated electrical bias, graphite-binding peptides form various ordered structures, such as well-ordered nanowires, dendritic structures, wavy wires, amorphous (disordered) structures, and islands. Systematic investigation of the correlation between peptide sequence and self-organizational characteristics reveals that the presence of the bias-sensitive amino acid modules in the peptide sequence has a significant effect on not only surface coverage, but also the morphological features of self-assembled structures. Our results show a new method to control peptide self-assembly by means of applied electrochemical bias, as well as peptide design-rules for construction of functional soft bio/solid interfaces that could be integrated in a wide range of practical implementations.

  3. 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.

  4. A 3D Simulation of a Moving Solid in Viscous Free-Surface Flows by Coupling SPH and DEM

    Directory of Open Access Journals (Sweden)

    Liu-Chao Qiu

    2017-01-01

    Full Text Available This work presents a three-dimensional two-way coupled method to simulate moving solids in viscous free-surface flows. The fluid flows are solved by weakly compressible smoothed particle hydrodynamics (SPH and the displacement and rotation of the solids are calculated using the multisphere discrete element method (DEM allowing for the contact mechanics theories to be used in arbitrarily shaped solids. The fluid and the solid phases are coupled through Newton’s third law of motion. The proposed method does not require a computational mesh, nor does it rely on empirical models to couple the fluid and solid phases. To verify the numerical model, the floating and sinking processes of a rectangular block in a water tank are simulated, and the numerical results are compared with experimental results reported in published literatures. The results indicate that the method presented in this paper is accurate and is capable of modelling fluid-solid interactions with a free-surface.

  5. The Effect of Composition on the Surface Finish of PS400: A New High Temperature Solid Lubricant Coating

    Science.gov (United States)

    DellaCorte, Christopher; Stanford, malcolm K.; Thomas, Fransua; Edmonds, Brian J.

    2010-01-01

    A new composite, multi-constituent, solid lubricant coating, NASA PS400, developed for high temperature tribological applications, exhibits a smoother surface finish after grinding and polishing than its predecessors PS200 and PS300. In this paper, the baseline composition of PS400 is modified to investigate each individual constituent s role on the achievable surface finish through a series of coating deposition, grinding, and polishing experiments. Furthermore, to explore the limits of compositional tailoring for improved tribological performance, several PS400 coatings were doped with additional solid lubricants (graphite, MoS2 and BN) and tribologically tested. The test results clearly showed that, compared to PS300 coatings, PS400 achieves a smoother surface finish via a reduced lubricant content. Coatings prepared with higher than the baseline level (10 wt%) of lubricants exhibited higher final surface roughness than the earlier generation PS300 coatings. Reducing or eliminating the one or both lubricants (fluorides or silver) did not further improve the surface finish suggesting that the current composition of PS400 is near optimal with respect to surface finish. Lastly, attempts to improve the poor initial room temperature tribological behavior of PS400 via the addition of traditional solid lubricants were unsuccessful. Based upon this work and earlier results it is expected that future research will concentrate on developing methods to produce a lubricious glaze on the rubbing surface during break in to ensure that low friction and wear are rapidly achieved.

  6. Experimental correlation of gas-liquid-solid mass transfer coefficient in a stirred tank using response surface methodology

    Science.gov (United States)

    Zhang, Xin; Duan, Xili; Gao, Zhengming

    2017-10-01

    In this paper, the three-phase (gas-liquid-solid) system in a stirred tank is experimentally studied. The response surface methodology (RSM) is used to analyze the three phase mass transfer coefficient under different conditions, i.e., rotation speeds (8, 10, and 12 s-1), volumetric solid content fractions (0, 6 and 12%), gas flow rates (6, 8, and 10 m3 h-1) and temperatures (40, 54, and 68 °C). With the RSM, it was found that all of these four operational parameters are significant in affecting the mass transfer coefficient, with the rotation speed being the most significant one. A new correlation is developed with a quadratic term for solid content fraction, indicating that there is a minimum value of mass transfer coefficient at a certain solid content fraction. Compared with traditional experimental design and correlation methods, the RSM in this study reduces experiment time and provides a better correlation to predict the mass transfer coefficient.

  7. The wettability of PTFE and glass surfaces by nanofluids.

    Science.gov (United States)

    Chaudhuri, Rajib Ghosh; Paria, Santanu

    2014-11-15

    Wetting of solid surfaces by surfactant solutions is well focused in the literature compared that of nanofluids. Similar to the surfactant solutions nanofluids are also able to reduce the surface tension as well as influence on contact angle at the solid, liquid and gas interface. The surface tension and wettability of two different nanofluids containing hydrophilic (TiO2) and hydrophobic (S) particles have been experimentally studied here. The surface tension reduction of nanofluids strongly depends on material property, particle size and as well as concentration. These parameters also influence the change in contact angle on both hydrophilic (glass) and hydrophobic (PTFE) surfaces. Three important factors such as surface tension, surface hydrophobicity after deposition of particles on a solid surface, and the disjoining pressure influence the final contact angle of nanofluids on a solid surface. Sulfur nanofluids show maximum enhancement in contact angle (30.6°) on the glass surface; on the other hand TiO2 nanofluids show maximum reductions in surface tension (25.4 mN/m) and contact angle on the PTFE surface (17.7°) with respect to pure water. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. The Surface of Nanoparticle Silicon as Studied by Solid-State NMR

    Directory of Open Access Journals (Sweden)

    Gary E. Maciel

    2012-12-01

    Full Text Available The surface structure and adjacent interior of commercially available silicon nanopowder (np-Si was studied using multinuclear, solid-state NMR spectroscopy. The results are consistent with an overall picture in which the bulk of the np-Si interior consists of highly ordered (“crystalline” silicon atoms, each bound tetrahedrally to four other silicon atoms. From a combination of 1H, 29Si and 2H magic-angle-spinning (MAS NMR results and quantum mechanical 29Si chemical shift calculations, silicon atoms on the surface of “as-received” np-Si were found to exist in a variety of chemical structures, with apparent populations in the order (a (Si–O–3Si–H > (b (Si–O–3SiOH > (c (HO–nSi(Sim(–OSi4−m−n ≈ (d (Si–O–2Si(HOH > (e (Si–O–2Si(–OH2 > (f (Si–O–4Si, where Si stands for a surface silicon atom and Si represents another silicon atom that is attached to Si by either a Si–Si bond or a Si–O–Si linkage. The relative populations of each of these structures can be modified by chemical treatment, including with O2 gas at elevated temperature. A deliberately oxidized sample displays an increased population of (Si–O–3Si–H, as well as (Si–O–3SiOH sites. Considerable heterogeneity of some surface structures was observed. A combination of 1H and 2H MAS experiments provide evidence for a substantial population of silanol (Si–OH moieties, some of which are not readily H-exchangeable, along with the dominant Si–H sites, on the surface of “as-received” np-Si; the silanol moieties are enhanced by deliberate oxidation. An extension of the DEPTH background suppression method is also demonstrated that permits measurement of the T2 relaxation parameter simultaneously with background suppression.

  9. Optimization of red pigment production by Monascus purpureus MTCC369 under solid-state fermentation using response surface methodology

    Directory of Open Access Journals (Sweden)

    Makhmur Ahmad

    2014-08-01

    Full Text Available Monascus pigments are used as a traditional food colorant in orient China, are produced by solid-state fermentation of non-glutinous rice using Monascus purpureus MTCC 369. Five nutrient parameters screened using Plackett-Burman experimental design were optimized by central composite design (central rotatory of response surface methodology for Monascus red pigment production under solid-state fermentation. Maximum red pigment production of 12 mg was predicted per gram of rice based solid medium containing 20g pre-soaked rice and 40 ml distilled water containing dextrose 74.59 g/l, peptone 5.54 g/l, NH4Cl 6.57 g/l, MnSO4.H2O 0.58 g/l and malt extract 14.46 g/l using response surface plots and point prediction tool of Design Expert 7.1:3 (Stat-Ease Inc., USA.

  10. Energy dissipation of highly charged ions interacting with solid surfaces; Energieeintrag langsamer hochgeladener Ionen in Festkoerperoberflaechen

    Energy Technology Data Exchange (ETDEWEB)

    Kost, D.

    2006-07-01

    Motivated by the incomplete scientific description of the relaxation of highly charged ions in front of solid surfaces and their energy balance, this thesis describes an advanced complementary study of determining deposited fractions and re-emitted fractions of the potential energy of highly charged ions. On one side, a calorimetric measurement setup is used to determine the retained potential energy and on the other side, energy resolved electron spectroscopy is used for measuring the reemitted energy due to secondary electron emission. In order to study the mechanism of energy retention in detail, materials with different electronic structures are investigated: Cu, n-Si, p-Si and SiO{sub 2}. In the case of calorimetry, a linear relationship between the deposited potential energy and the inner potential energy of the ions was determined. The total potential energy which stays in the solid remains almost constant at about (80 {+-} 10) %. Comparing the results of the Cu, n-Si and p-Si targets, no significant difference could be shown. Therefore we conclude that the difference in energy deposition between copper, n-doped Si and p-doped Si is below 10 %, which is significantly lower than using SiO{sub 2} targets. For this purpose, electron spectroscopy provides a complementary result. For Cu and Si surfaces, an almost linear increase of the re-emitted energy with increasing potential energy of the ion up to Ar{sup 7+} was also observed. The ratio of the re-emitted energy is about (10 {+-} 5) % of the total potential energy of the incoming ion, almost independent of the ion charge state. In contrast, an almost vanishing electron emission was observed for SiO{sub 2} and for charge states below q=7. For Ar{sup 8+} and Ar{sup 9+}, the electron emission increased due to the contribution of the projectile LMM Auger electrons and the re-emitted energy amounts up to 20 % for Cu and Si and around 10 % for SiO{sub 2}. These results are in good agreement with the calorimetric

  11. 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.

  12. Application of solid state NMR for the study of surface bound species and fossil fuels

    Science.gov (United States)

    Althaus, Stacey

    Recent advances in solid state NMR have been utilized to study a variety of systems. These advancements have allowed for the acquisition of sequences previously only available for solution state detection. The protocol for the measurement of coals and other carbonaceous materials was updated to incorporate the recent advancements in fast magic angle spinning (MAS) and high magnetic fields. Argonne Premium Coals were used to test the sensitivity and resolution of the experiments preformed at high field and fast MAS. The higher field spectra were shown to be slightly less sensitive than the traditional lower field spectra, however, the new high field fast MAS spectra had better resolution. This increased resolution allowed for the separation of a variety of different functional groups, thereby allowing the composition of the coal to be determined. The use of 1 H detection allowed for 2D spectra of coals for the first time. These spectra could be filtered to examine either through-space or through-bond correlations. Indirect detection via 1 H was also pivotal in the detection of natural abundance 15 N spectra. Through-space and through-bond 2D spectra of natural abundance bulk species are shown with a sensitivity increase of 15 fold over traditional detection. This sensitivity enhancement allowed for the detection of natural abundance 15 N surface bound species in 2D, something that could not be acquired via traditional methods. The increased efficiency of the through-space magnetization transfer, Cross polarization, at fast MAS compared to the slower MAS rates is shown. The through-bond magnetization transfer via INEPT was examined and the effect of J-coupling is confirmed. Solid State NMR can be utilized to help improve catalytic interactions. Solid state NMR was used to examine the aldol condensation between p-nitrobenzaldehyde and acetone. The formation of a stable intermediate with p-nitrobenzaldehyde was found on the primary functionalized amine mesoporous

  13. Applications of magnetic surface imprinted materials for solid phase extraction of levofloxacin in serum samples.

    Science.gov (United States)

    Xiao, Deli; Wang, Cuixia; Dai, Hao; Peng, Jun; He, Jia; Zhang, Kai; Kong, Sumei; Qiu, Panzi; He, Hua

    2015-05-01

    In this work, molecularly imprinted magnetic carbon nanotubes (MCNTs@MIPs) was prepared with surface imprinting technique for extraction of levofloxacin in serum samples. The preparation of molecularly imprinted polymers (MIPs) used levofloxacin as template, methacrylic acid as functional monomer, and ethylene glycol dimethacrylate as cross-linker, and the magnetic carbon nanotubes (MCNTs) was synthesized by solvothermal method. The prepared polymers not only can be separated and collected easily by an external magnetic, but also exhibited high specific surface area and high selectivity to template molecules. Kinetic adsorption and static adsorption capacity investigations indicated that the synthesized MCNTs@MIPs had excellent recognition towards levofloxacin. Furthermore, magnetic solid phase extraction (MSPE) using the prepared MCNTs@MIPs as sorbent was then investigated, and an efficient sample cleanup was obtained with recoveries ranged from 78.7 ± 4.8 % to 83.4 ± 4.1%. In addition, several parameters, including the pH of samples, the amount of MCNTs@MIPs, the adsorption and desorption times, and the eluent, were investigated to obtain optimal extraction efficiency. Under the optimal extraction conditions, the stability of the polymer was also evaluated, and the average recovery reduced less than 7.6% after 5 cycles. MCNTs@MIPs successfully applied in the preconcentration and determination of levofloxacin in serum sample suggested that the MSPE method based on the novel polymers could be a promising alternative for selective and efficient extraction of trace amounts of pharmaceutical substances in bio-matrix samples. Copyright © 2015 John Wiley & Sons, Ltd.

  14. Evolution of the surface structures of solids under irradiation with high energy heavy ions

    CERN Document Server

    Didyk, A Y; Cheblukov, Y N; Dmitriev, S N; Hofmann, A; Semina, V K; Suvorov, A L

    2002-01-01

    The results on the study of surface structure of solids, like metals, metal alloys, amorphous metal alloys and highly oriented pyrolytic graphite (HOPG) under irradiation with heavy sup 8 sup 6 Kr ions (ion energy is 245 MeV, irradiation fluences are 10 sup 1 sup 3 , 10 sup 1 sup 4 , 10 sup 1 sup 5 cm sup - sup 2) and sup 2 sup 0 sup 9 Bi (ion energy is 705 MeV, irradiation fluences are 10 sup 1 sup 2 , 10 sup 1 sup 3 cm sup - sup 2) are presented. The sputtering coefficients for metals (Ni, W, Au), stainless steel Cr18Ni10, amorphous alloy Ni sub 5 sub 8 Nb sub 4 sub 2 and HOPG are measured. It is shown that the sputtering coefficients of annealed polycrystals (Ni, Au) and single crystals (W, HOPG) are not large at low defect concentration in materials. At this stage, the sputtering of grain boundaries predominantly takes place. The sputtering yields become to increase significantly with the growth of damage concentration at ion fluences of the order of 10 sup 1 sup 5 cm sup - sup 2. Analogous results were o...

  15. Controlling DNA Translocation Speed through Solid-State Nanopores by Surface Charge Modulation

    Science.gov (United States)

    Meller, Amit

    2013-03-01

    The Nanopore method is an emerging technique, which extends gel-electrophoresis to the single-molecule level and allows the analysis of DNAs, RNAs and DNA-protein complexes. The strength of the technique stems from two fundamental facts: First, nanopores due to their nanoscale size can be used to uncoil biopolymers, such as DNA or RNA and slide them in a single file manner that allows scanning their properties. Consequently, the method can be used to probe short as well as extremely long biopolymers, such as genomic DNA with high efficiency. Second, electrostatic focusing of charged biopolymers into the nanopore overcomes thermally driven diffusion, thus facilitating an extremely efficient end-threading (or capture) of DNA. Thus, nanopores can be used to detect minute DNA copy numbers, circumventing costly molecular amplification such as Polymerase Chain Reaction. A critical factor, which determines the ability of nanopore to distinguish fine properties within biopolymers, such as the location of bound small-molecules, proteins, or even the nucleic acid's sequence, is the speed at which molecules are translocated through the pore. When the translocation speed is too high the electrical noise masks the desired signal, thus limiting the utility of the method. Here I will discuss new experimental results showing that modulating the surface charge inside the pore can effectively reduce the translocation speed through solid-state nanopores fabricated in thin silicon nitride membranes. I will present a simple physical model to account for these results.

  16. Drop impact on a solid surface: short time self-similarity

    CERN Document Server

    Philippi, Julien; Antkowiak, Arnaud

    2015-01-01

    The early stages of drop impact onto a solid surface are considered. Detailed numerical simulations and detailed asymptotic analysis of the process reveal a self-similar structure both for the velocity field and the pressure field. The latter is shown to exhibit a maximum not near the impact point, but rather at the contact line. The motion of the contact line is furthermore shown to exhibit a 'tank treading' motion. These observations are apprehended at the light of a variant of Wagner theory for liquid impact. This framework offers a simple analogy where the fluid motion within the impacting drop may be viewed as the flow induced by a flat rising expanding disk. The theoretical predictions are found to be in very close agreement both qualitatively and quantitatively with the numerical observations for about three decades in time. Interestingly the inviscid self-similar impact pressure and velocities are shown to depend solely on the self-similar variables $(r/\\sqrt{t},z/\\sqrt{t})$. The structure of the boun...

  17. A numerical study of thermocapillary migration of a small liquid droplet on a horizontal solid surface

    Science.gov (United States)

    Nguyen, Huy-Bich; Chen, Jyh-Chen

    2010-06-01

    In the present study, the transient thermocapillary migration of a small liquid droplet on a horizontal solid surface is numerically investigated. The droplet has a large static contact angle and a high aspect ratio of the maximum height of the droplet to its footprint. The Navier-Stokes and energy equations for both the droplet and surrounding air are solved through the finite element method. The evolution of the isotherms, the flow fields and the contact angle hysteresis are presented. Two asymmetric thermocapillary vortices appear inside the droplet. The variation of the size of the thermocapillary vortex during the migration process causes the speed of the droplet to first increase significantly, and then decrease gradually to approach a constant value. The higher imposed temperature gradient causes the droplet velocity to reach its maximal value earlier and have a higher final speed. If the static contact angle of the droplet is less than (or higher) than 90°, the droplet speed is lower (or higher) since the net thermocapillary momentum in the horizontal direction is diminished (or enhanced) by the presence of capillary force. The present results for the migration velocity and the contact angle hysteresis for a squalane droplet are also in good agreement with the previous experimental results.

  18. Dynamic encapsulation of hydrophilic nisin in hydrophobic poly (lactic acid) particles with controlled morphology by a single emulsion process.

    Science.gov (United States)

    Ji, Shaowen; Lu, Jue; Liu, Zhiguo; Srivastava, Devesh; Song, Anna; Liu, Yan; Lee, Ilsoon

    2014-06-01

    Hydrophilic nisin-loaded hydrophobic poly (lactic acid) (PLA) particles with controlled size and shape were successfully produced utilizing a one-step single emulsification method. Preliminary shear stress and temperature tests showed that there was no significant loss in the nisin inhibition activity during this process. PLA/nisin composite particles were prepared into solid nanocomposite spheres (50-200 nm) or hollow microcomposite spheres (1-5 μm) under the operative conditions developed in our previous study, in which the hydrophilic nisin in the aqueous phase solution could be entrapped in the hydrophobic polymer in the emulsification process generating either single or multiple emulsions. The incorporation of nisin in PLA had little effect on key processing conditions, which allows the dynamic control of the morphology and property of resulting particles. Microscopic and surface analyses suggested that nisin was dispersed uniformly inside the polymer matrix and adsorbed on the particle surface. The encapsulation amount and efficiency were enhanced with the increase in nisin loading in the aqueous solution. Unique reversible control of particle size and shape by this process was successfully applied in the nisin encapsulation. Alternating temperature in the repeating emulsification steps improved the encapsulation efficiency while generated particles in desired size and shape. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. TOOL FOR MONITORING HYDROPHILIC CONTAMINANTS ...

    Science.gov (United States)

    Global emissions of persistent bioconcentratable organic chemicals have resulted in a wide range of adverse ecological effects. Consequently, industry was led to develop less persistent, more water soluble, polar or hydrophilic organic compounds (HpOCs), which generally have low bioconcentration factors. However, evidence is growing that the large fluxes of these seemingly more environmentally friendly compounds (e.g., pesticides, prescription and non-prescription drugs, personal care and common consumer products, industrial and domestic-use chemicals and their degradation products) into aquatic systems on a world-wide basis may be responsible for incidents of acute toxicity and sub-lethal chronic abnormalities. These adverse effects include altered behavior, neurotoxicity, and severely impaired reproduction. Furthermore, the presence of these HpOCs likely plays a major role in the endocrine disrupting effects of complex mixtures of chemicals present in aquatic environments. In regard to physiological effects, pharmaceuticals are of particular concern because they are designed to elicit diverse pharmacological responses at very low doses. Unfortunately, the effects of this class of HpOCs on non-target, aquatic organisms are largely unknown. The research focused on in the subtasks is the development and application of state-of the-art technologies to meet the needs of the public, Office of Water, and ORD in the area of Water Quality. Located In the subtasks are

  20. Model for growth of fractal solid state surface and possibility of its verification by means of atomic force microscopy

    Science.gov (United States)

    Kulikov, D. A.; Potapov, A. A.; Rassadin, A. E.; Stepanov, A. V.

    2017-10-01

    In the paper, methods of verification of models for growth of solid state surface by means of atomic force microscopy are suggested. Simulation of growth of fractals with cylindrical generatrix on the solid state surface is presented. Our mathematical model of this process is based on generalization of the Kardar-Parisi-Zhang equation. Corner stones of this generalization are both conjecture of anisotropy of growth of the surface and approximation of small angles. The method of characteristics has been applied to solve the Kardar-Parisi-Zhang equation. Its solution should be considered up to the gradient catastrophe. The difficulty of nondifferentiability of fractal initial generatrix has been overcome by transition from a mathematical fractal to a physical one.

  1. Surface charge accumulation of solid insulator under nanosecond pulse in vacuum: 3D distribution features and mechanism

    Science.gov (United States)

    Qi, Bo; Gao, Chunjia; Sun, Zelai; Li, Chengrong

    2017-11-01

    Surface charge accumulation can incur changes in electric field distribution, involved in the electron propagation process, and result in a significant decrease in the surface flashover voltage. The existing 2D surface charge measurement fails to meet the actual needs in real engineering applications that usually adopt the 45° conical frustum insulators. The present research developed a novel 3D measurement platform to capture surface charge distribution on solid insulation under nanosecond pulse in a vacuum. The results indicate that all surface charges are positive under a positive pulse and negative under a negative pulse. Surface charges tend to accumulate more near the upper electrode. Surface charge density increases significantly with the increase in pulse counts and amplitudes. Accumulation of surface charge results in a certain decrease of flashover voltage. Taking consideration of the secondary electron emission for the surface charge accumulation, four materials were obtained to demonstrate the effects on surface charge. Combining the effect incurred by secondary electron emission and the weighty action taken by surface charge accumulation on the flashover phenomena, the discharge mechanism along the insulator surface under nanosecond pulse voltage was proposed.

  2. Modulation of protein adsorption by poloxamer 188 in relation to polysorbates 80 and 20 at solid surfaces.

    Science.gov (United States)

    Kim, Hyojin L; McAuley, Arnold; Livesay, Brynn; Gray, Warren D; McGuire, Joseph

    2014-04-01

    Poloxamer 188 (BASF Pluronic® F68) is widely used as a shear-protective excipient to enhance cell yield in agitated cultures and reduce cell adhesion in stationary cultures. However, little is known in any quantitative sense of its effect on protein adsorption and aggregation. Optical waveguide lightmode spectroscopy was used here to compare the adsorption kinetics exhibited by poloxamer 188, and polysorbates 80 and 20, in the presence and absence of a model protein (chicken egg white lysozyme) and in separate experiments, a recombinant protein (human granulocyte colony-stimulating factor) at hydrophilic, silica-titania surfaces. Experiments were performed in sequential and competitive adsorption modes, enabling the adsorption kinetic patterns to be interpreted in a fashion revealing the dominant mode of surfactant-mediated stabilization of protein in each case. Kinetic results showed that polysorbates 80 and 20 are able to inhibit protein adsorption only by their preferential location at an interface to which they show sufficient affinity, and not by formation of less surface active, protein-surfactant complexes. On the other hand, poloxamer 188 is able to inhibit protein adsorption by entering into formation of protein-surfactant complexes of low adsorption affinity (i.e., high colloidal stability), and not by its preferential location at the interface. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  3. Influence of liquid surface segregation on the pitting corrosion behavior of semi-solid metal high pressure die cast alloy F357

    CSIR Research Space (South Africa)

    Moller, H

    2009-01-01

    Full Text Available Semi-solid metal processing results in liquid segregation at the surface of the components. The pitting behaviour of this surface layer of semi-solid metal processed alloy F357 was compared with the centre (or bulk) of cast plates in 3.5% Na...

  4. Inverse gas chromatography a tool to follow physicochemical modifications of pharmaceutical solids: Crystal habit and particles size surface effects.

    Science.gov (United States)

    Cares-Pacheco, M G; Calvet, R; Vaca-Medina, G; Rouilly, A; Espitalier, F

    2015-10-15

    Powders are complex systems and so pharmaceutical solids are not the exception. Nowadays, pharmaceutical ingredients must comply with well-defined draconian specifications imposing narrow particle size range, control on the mean particle size, crystalline structure, crystal habits aspect and surface properties of powders, among others. The different facets, physical forms, defects and/or impurities of the solid will alter its interaction properties. A powerful way of studying surface properties is based on the adsorption of an organic or water vapor on a powder. Inverse gas chromatography (IGC) appears as a useful method to characterize the surface properties of divided solids. The aim of this work is to study the sensitivity of IGC, in Henry's domain, in order to detect the impact of size and morphology in surface energy of two crystalline forms of an excipient, d-mannitol. Surface energy analyses using IGC have shown that the α form is the most energetically active form. To study size and shape influence on polymorphism, pure α and β mannitol samples were cryomilled (CM) and/or spray dried (SD). All forms showed an increase of the surface energy after treatment, with a higher influence for β samples (γs(d) of 40-62 mJ m(-2)) than for α mannitol samples (γs(d) of 75-86 mJ m(-2)). Surface heterogeneity analysis in Henry's domain showed a more heterogeneous β-CM sample (62-52 mJ m(-2)). Moreover, despite its spherical shape and quite homogeneous size distribution, β-SD mannitol samples showed a slightly heterogeneous surface (57-52 mJ m(-2)) also higher than the recrystallized β pure sample (∼40 mJ m(-2)). Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Advanced LWIR hyperspectral sensor for on-the-move proximal detection of liquid/solid contaminants on surfaces

    Science.gov (United States)

    Giblin, Jay P.; Dixon, John; Dupuis, Julia R.; Cosofret, Bogdan R.; Marinelli, William J.

    2017-05-01

    Sensor technologies capable of detecting low vapor pressure liquid surface contaminants, as well as solids, in a noncontact fashion while on-the-move continues to be an important need for the U.S. Army. In this paper, we discuss the development of a long-wave infrared (LWIR, 8-10.5 μm) spatial heterodyne spectrometer coupled with an LWIR illuminator and an automated detection algorithm for detection of surface contaminants from a moving vehicle. The system is designed to detect surface contaminants by repetitively collecting LWIR reflectance spectra of the ground. Detection and identification of surface contaminants is based on spectral correlation of the measured LWIR ground reflectance spectra with high fidelity library spectra and the system's cumulative binary detection response from the sampled ground. We present the concepts of the detection algorithm through a discussion of the system signal model. In addition, we present reflectance spectra of surfaces contaminated with a liquid CWA simulant, triethyl phosphate (TEP), and a solid simulant, acetaminophen acquired while the sensor was stationary and on-the-move. Surfaces included CARC painted steel, asphalt, concrete, and sand. The data collected was analyzed to determine the probability of detecting 800 μm diameter contaminant particles at a 0.5 g/m2 areal density with the SHSCAD traversing a surface.

  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. Gas/Solid Carbon Branching Ratios in Surface Mediated Reactions and the Incorporation of Carbonaceous Material into Planetesimals

    Science.gov (United States)

    Nuth, Joseph A.; Johnson, Natasha M.; Ferguson, Frank T.; Carayon, Alicia

    2016-01-01

    We report the ratio of the initial carbon available as CO that forms gas-phase compounds compared to the fraction that deposits as a carbonaceous solid (the gas solid branching ratio) as a function of time and temperature for iron, magnetite, and amorphous iron silicate smoke catalysts during surface-mediated reactions in an excess of hydrogen and in the presence of N2. This fraction varies from more than 99 for an amorphous iron silicate smoke at 673 K to less than 40% for a magnetite catalyst at 873 K. The CO not converted into solids primarily forms methane, ethane, water, and CO2, as well as a very wide range of organic molecules at very low concentration. Carbon deposits do not form continuous coatings on the catalytic surfaces, but instead form extremely high surface area per unit volume filamentous structures. While these structures will likely form more slowly but over much longer times in protostellar nebulae than in our experiments due to the much lower partial pressure of CO, such fluffy coatings on the surfaces of chondrules or calcium aluminum inclusions could promote grain-grain sticking during low-velocity collisions.

  8. Excitation energy migration in yellow fluorescent protein (citrine) layers adsorbed on modified gold surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Yusoff, Hanis Mohd, E-mail: hanismy@umt.edu.my [Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8578, Miyagi (Japan); Department of Chemical Sciences, Faculty of Science, Universiti Malaysia Terengganu, 21030 Kuala Terengganu, Terengganu (Malaysia); Rzeźnicka, Izabela I. [Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8578, Miyagi (Japan); Institute for International Education, Tohoku University, Katahira, 2-chome, Aoba-ku, Sendai 980-8577, Miyagi (Japan); Hoshi, Hirotaka [Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8578 (Japan); Kajimoto, Shinji; Horimoto, Noriko Nishizawa [Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8578, Miyagi (Japan); Sogawa, Kazuhiro [Department of Biomolecular Sciences, Graduate School of Life Sciences, Tohoku University, Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8578 (Japan); Fukumura, Hiroshi, E-mail: fukumura@m.tohoku.ac.jp [Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki Aza-Aoba, Aoba-ku, Sendai 980-8578, Miyagi (Japan)

    2013-09-01

    The nature of functional proteins adsorbed on solid surfaces is interesting from the perspective of developing of bioelectronics and biomaterials. Here we present evidence that citrine (one of yellow fluorescent protein variants) adsorbed on modified gold surfaces would not undergo denaturation and energy transfer among the adsorbed citrine molecules would occur. Gold substrates were chemically modified with 3-mercaptopropionic acid and tert-butyl mercaptan for the preparation of hydrophilic and hydrophobic surfaces, respectively. A pure solution of citrine was dropped and dried on the modified gold substrates and their surface morphology was studied with scanning tunnelling microscopy (STM). The obtained STM images showed multilayers of citrine adsorbed on the modified surfaces. On hydrophobic surfaces, citrine was adsorbed more randomly, formed various non-uniform aggregates, while on hydrophilic surfaces, citrine appeared more aligned and isolated uniform protein clusters were observed. Fluorescence lifetime and anisotropy decay of these dried citrine layers were also measured using the time correlated single photon counting method. Fluorescence anisotropy of citrine on the hydrophobic surface decayed faster than citrine on the hydrophilic surface. From these results we concluded that fluorescence energy migration occurred faster among citrine molecules which were randomly adsorbed on the hydrophobic surface to compare with the hydrophilic surface.

  9. Photocatalysis and hydrophilicity of doped TiO2 thin films.

    Science.gov (United States)

    Lee, Young Cheol; Hong, Young Pyo; Lee, Ha Yong; Kim, Hoon; Jung, Young Jin; Ko, Kyung Hyun; Jung, Hyun Seok; Hong, Kug Sun

    2003-11-01

    TiO(2) thin films were prepared using the dip-coating method with a polymeric sol including additives such as Al, W, and Al+W to examine two major properties: photocatalysis and hydrophilicity. W-doped films showed the best photocatalytic efficiency, while Al-doped film was poorer than undoped samples. However, good hydrophilicity in terms of saturation contact angle and surface conversion rate was found in Al- and (Al+W)-mixed-doped films. It was found that deep electron-hole traps and high surface acidity of W-doped TiO(2) thin film were the major factors in high photocatalytic efficiency. In addition, low surface acidities of Al- and (Al+W)-doped films provided better hydrophilicity than W-doped ones. However, the amount of [Ti(3+)] point defects on the surface was another major factor, probably the most important, in getting the best hydrophilicity. Conclusively, it seemed that many parts of the photocatalysis mechanism depend more on bulk-related properties than do those of hydrophilicity, which can be defined as an interfacial (surface) or near-surface-restricted process.

  10. Surface chemistry of group 11 atomic layer deposition precursors on silica using solid-state nuclear magnetic resonance spectroscopy

    Science.gov (United States)

    Pallister, Peter J.; Barry, Seán T.

    2017-02-01

    The use of chemical vapour deposition (CVD) and atomic layer deposition (ALD) as thin film deposition techniques has had a major impact on a number of fields. The deposition of pure, uniform, conformal thin films requires very specific vapour-solid reactivity that is largely unknown for the majority of ALD and CVD precursors. This work examines the initial chemisorption of several thin film vapour deposition precursors on high surface area silica (HSAS) using 13C, 31P, and quantitative 29Si nuclear magnetic resonance spectroscopy (NMR). Two copper metal precursors, 1,3-diisopropyl-imidazolin-2-ylidene copper (I) hexamethyldisilazide (1) and 1,3-diethyl-imidazolin-2-ylidene copper(I) hexamethyldisilazide (2), and one gold metal precursor, trimethylphosphine gold(III) trimethyl (3), are examined. Compounds 1 and 2 were found to chemisorb at the hydroxyl surface-reactive sites to form a ||-O-Cu-NHC surface species and fully methylated silicon (||-SiMe3, due to reactivity of the hexamethyldisilazane (HMDS) ligand on the precursor) at 150 °C and 250 °C. From quantitative 29Si solid-state NMR (SS-NMR) spectroscopy measurements, it was found that HMDS preferentially reacts at geminal disilanol surface sites while the copper surface species preferentially chemisorbed to lone silanol surface species. Additionally, the overall coverage was strongly dependent on temperature, with higher overall coverage of 1 at higher temperature but lower overall coverage of 2 at higher temperature. The chemisorption of 3 was found to produce a number of interesting surface species on HSAS. Gold(III) trimethylphosphine, reduced gold phosphine, methylated phosphoxides, and graphitic carbon were all observed as surface species. The overall coverage of 3 on HSAS was only about 10% at 100 °C and, like the copper compounds, had a preference for lone silanol surface reactive sites. The overall coverage and chemisorbed surface species have implications to the overall growth rate and purity of

  11. Comparison of Microleakage and Penetration Depth between Hydrophilic and Hydrophobic Sealants in Primary Second Molar.

    Science.gov (United States)

    Gawali, Pritesh N; Chaugule, Vishwas B; Panse, Amey M

    2016-01-01

    Optimal pit and fissure sealing is determined by surface preparation techniques and choice of materials. The performance of pit and fissure sealant materials has been intensively investigated, yet no single product is reported as an ideal sealant. In children, moisture control during cavity preparation is always a big challenge, and hence, hydrophilic sealants have been developed. To compare the microleakage and penetration depth of hydrophilic and hydrophobic sealants using acid-etching on dry and moist surfaces. Recently, extracted 28 2nd primary molars are assigned to two groups (hydrophobic group I; hydrophilic group II) depending on the surface condition (dry group: A1 and B1; moist group: A2 and B2) of 7 teeth in each group. Samples from group A1 and B1 are cleaned and dried with a 3-way syringe and etched with etching gel, and sealant is applied to the fissures and cured with visible light. Sample from A2 and B2 are immersed in 0.1 mL of fresh whole human saliva for 20 seconds and dried using a pellet cotton, and the same procedure is carried out. All samples are subjected to 1000 thermal cycles and sectioned to compare the depth of penetration and microleakage. Sections will be examined under light microscope and analyzed using an image analysis software (SigmaScan). The least microleakage was seen with hydrophilic sealant under moist surface condition, and the depth of penetration of hydrophobic sealant was found to be better than that of hydrophilic sealant in both dry and moist surface conditions. Hydrophilic pit and fissure sealants showed higher tolerance to saliva contamination with less microleakage, but in terms of penetration ability hydrophobic sealants were found to be superior. Gawali PN, Chaugule VB, Panse AM. Comparison of Microleakage and Penetration Depth between Hydrophilic and Hydrophobic Sealants in Primary Second Molar. Int J Clin Pediatr Dent 2016;9(4):291-295.

  12. 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

    2016-01-22

    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.

  13. A solid phase extraction based non-disruptive sampling technique to investigate the surface chemistry of macroalgae.

    Science.gov (United States)

    Cirri, Emilio; Grosser, Katharina; Pohnert, Georg

    2016-01-01

    The surface chemistry of aquatic organisms determines their biotic interactions. Metabolites in the spatially limited laminar boundary layer mediate processes, such as antifouling, allelopathy and chemical defense against herbivores. However, very few methods are available for the investigation of such surface metabolites. An approach is described in which surfaces are extracted by means of C18 solid phase material. By powdering wet algal surfaces with this material, organic compounds are adsorbed and can be easily recovered for subsequent liquid chromatography/mass spectrometry (LC/MS) and gas chromatography/mass spectrometry (GC/MS) investigations. The method is robust, picks up metabolites of a broad polarity range and is easy to handle. It is more universal compared to established solvent dipping protocols and it does not cause damage to the test organisms. A protocol is introduced for the macroalgae Fucus vesiculosus, Caulerpa taxifolia and Gracilaria vermiculophylla, but it can be easily transferred to other aquatic organisms.

  14. Salvinia-Effect-Inspired "Sticky" Superhydrophobic Surfaces by Meniscus-Confined Electrodeposition.

    Science.gov (United States)

    Zheng, Deyin; Jiang, Youhua; Yu, Wentao; Jiang, Xiufen; Zhao, Xin; Choi, Chang-Hwan; Sun, Guangyi

    2017-11-28

    Inspired by the Salvinia effect, we report the fabrication and characterization of a novel "sticky" superhydrophobic surface sustaining a Cassie-Baxter wetting state for water droplets with high contact angles but strong solid-liquid retention. Unlike superhydrophobic surfaces mimicking the lotus or petal effect, whose hydrophobicity and droplet retention are typically regulated by hierarchical micro- and nanostructures made of a homogeneous material with the same surface energy, our superhydrophobic surface merely requires singular microstructures covered with a hydrophobic coating but creatively coupled with hydrophilic tips with different surface energy. Hydrophilic tips are selectively formed by meniscus-confined electrodeposition of a metal (e.g., nickel) layer on top of hydrophobic microstructures. During the electrodeposition process, the superhydrophobic surface retains its plastron so that the electrolyte cannot penetrate into the cavity of hydrophobic microstructures, consequently making the electrochemical reaction between solid and electrolyte occur only on the tip. In contrast to typical superhydrophobic surfaces where droplets are highly mobile, the "sticky" superhydrophobic surface allows a water droplet to have strong local pinning and solid-liquid retention on the hydrophilic tips, which is of great significance in many droplet behaviors such as evaporation.

  15. Adhesion of Cryptosporidium parvum and Giardia lamblia to solid surfaces: the role of surface charge and hydrophobicity

    NARCIS (Netherlands)

    Dai, X.; Boll, J.; Hayes, M.E.; Aston, D.E.

    2004-01-01

    Adhesion of Cryptosporidium parvum and Giardia lamblia to four materials of different surface charge and hydrophobicity was investigated. Glass beads were used with and without three polymer coatings: aminosilines (A0750), fluorosilines (T2494), an amino cationic polymer. Surface charge density and

  16. 21 CFR 201.319 - Water-soluble gums, hydrophilic gums, and hydrophilic mucilloids (including, but not limited to...

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 4 2010-04-01 2010-04-01 false Water-soluble gums, hydrophilic gums, and... Specific Labeling Requirements for Specific Drug Products § 201.319 Water-soluble gums, hydrophilic gums... been associated with the ingestion of water-soluble gums, hydrophilic gums, and hydrophilic mucilloids...

  17. Molecular dynamics analysis of the friction between a water-methanol liquid mixture and a non-polar solid crystal surface

    Science.gov (United States)

    Nakaoka, Satoshi; Yamaguchi, Yasutaka; Omori, Takeshi; Joly, Laurent

    2017-05-01

    We performed molecular dynamics analysis of the momentum transfer at the solid-liquid interface for a water-methanol liquid mixture between parallel non-polar solid walls in order to understand the strong decrease of the friction coefficient (FC) induced by the methanol adsorption at the surface observed in our previous work [S. Nakaoka et al., Phys. Rev. E 92, 022402 (2015)]. In particular, we extracted the individual contributions of water and methanol molecules to the total FC and found that the molecular FC for methanol was larger than that for water. We further showed that the reduction of the total solid-liquid FC upon the increase of the methanol molar fraction in the first adsorption layer occurred as a result of a decrease in the molecular number density as well as a decrease in the molecular FCs of both molecules. Analysis of the molecular orientation revealed that the decrease of the molecular FC of methanol resulted from changes of the contact feature onto the solid surface. Specifically, methanol molecules near the solid surface had their C-O bond parallel to the surface with both CH3 and O sites contacting the solid at low methanol molar fraction, while they had their C-O bond outward from the surface with only the CH3 site contacting the solid at higher methanol molar fraction. The mechanisms discussed in this work could be used to search for alternative water additives to further reduce the solid-liquid friction.

  18. Production of Valuable Lipophilic Compounds by Using Three Types of Interface Bioprocesses: Solid-Liquid Interface Bioreactor, Liquid-Liquid Interface Bioreactor, and Extractive Liquid-Surface Immobilization System.

    Science.gov (United States)

    Oda, Shinobu

    2017-01-01

    Bioconversions such as enzymatic and microbial transformations are attractive alternatives to organic synthesis because of practical advantages such as resource conservation, energy efficiency, and environmentally harmonic properties. In addition, the production of secondary metabolites through microbial fermentation is also useful for manufacturing pharmaceuticals, agricultural chemicals, and aroma compounds. For microbial production of useful chemicals, the authors have developed three unique interfacial bioprocesses: a solid-liquid interface bioreactor (S/L-IBR), a liquid-liquid interface bioreactor (L/L-IBR), and an extractive liquid-surface immobilization (Ext-LSI) system. The S/L-IBR comprises a hydrophobic organic solvent (upper phase), a microbial film (middle phase), and a hydrophilic gel such as an agar plate (lower phase); the L/L-IBR and the Ext-LSI consist of a hydrophobic organic solvent (upper phase), a fungal mat with ballooned microspheres (middle phase), and a liquid medium (lower phase). All three systems have unique and practically important characteristics such as utilization of living cells, high concentration of lipophilic substrates/products in an organic phase, no requirement for aeration and agitation, efficient supply of oxygen, easy recovery of product, high regio- and stereoselectivity, and wide versatility. This paper reviews the principle, construction, characteristics, and application of these interfacial systems for producing lipophilic compounds such as useful aroma compounds, citronellol-related compounds, β-caryophyllene oxide, and 6-penty-α-pyrone.

  19. Solid-phase extraction and HPLC determination of fluoroquinolones in surface waters.

    Science.gov (United States)

    Sturini, Michela; Speltini, Andrea; Pretali, Luca; Fasani, Elisa; Profumo, Antonella

    2009-09-01

    An investigation on filtration procedures and SPE sorbents used for the determination of traces of the most common veterinary fluoroquinolones (FQs), marbofloxacin (MAR) and enrofloxacin (ENR) used as antibacterial agents in cattle and swine farms in the province of Pavia (Italy), was performed in natural waters. The filter composition and the sorbent used in the SPE strongly influence the correct recovery, both in terms of total and dissolved FQs concentration. An accurate comparison among different filters and SPE sorbents showed that a full determination of analytes was possible on nylon filters followed by anionic (WAX) and hydrophilic-lipophilic balance (HLB) resins as SPE. Quantitative analysis was done by chromatography with fluorescence detection (HPLC-FD). Fluoroquinolones recovery was between 90 and 116% with RSD not greater than 10% (sample volume 250 mL). The developed method allowed to determine both dissolved and NOM-absorbed fractions of FQs, therefore a full determination of the analytes was possible. Limits of detection (LOD) and quantification (LOQ) were, respectively, 0.7 and 2.2 ng/L for ENR and 2 and 6 ng/L for MAR. The kinetics of degradation under solar light was explored.

  20. Effects of different surface modification and contents on municipal solid waste incineration fly ash/epoxy composites.

    Science.gov (United States)

    Goh, C K; Valavan, S E; Low, T K; Tang, L H

    2016-12-01

    Incineration fly ash, a waste from municipal solid waste incineration plant can be used to replace conventional filler as reinforcing filler to enhance the mechanical strength of a composite. Surface modification was performed on the incineration fly ash before mixing into the soft polymer matrix so as to improve interfacial bond of the filler and epoxy resin. In this study, detailed characterisation of mechanical, morphological and leaching behaviours of municipal solid waste incineration (MSWI) fly ash infused composite has been carried out. Flexural and tensile test was conducted to determine the effect on mechanical properties of the composite by varying the concentration of incineration fly ash filler added into polymer matrix and surface modification of incineration fly ash filler using silane coupling agent and colloidal mesoporous silica (CMS). The results indicated that composite infused with incineration fly ash filler surface treated with CMS shown improvement on the tensile and flexural strengths. In addition, SEM images showed that surface modification of incineration fly ash with colloidal mesoporous silica enhanced the interfacial bonding with polymer resin which explained the improvement of mechanical strength. Leaching test showed result of toxic metals such as Pb, Zn, Fe, Cu, Cr, Cd and Rb immobilised in the polymer matrix of the composite. Hence, the use of MSWI fly ash as reinforcing filler in the composite appears green and sustainable because this approach is a promising opportunity to substitute valuable raw material with MSWI fly ash. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. Effect of Equal Channel Angular Pressing on the Surface Roughness of Solid State Recycled Aluminum Alloy 6061 Chips

    Directory of Open Access Journals (Sweden)

    Adel Taha Abbas

    2017-01-01

    Full Text Available Solid state recycling through hot extrusion is a promising technique to recycle machining chips without remelting. Furthermore, equal channel angular pressing (ECAP technique coupled with the extruded recycled billet is introduced to enhance the mechanical properties of recycled samples. In this paper, the surface roughness of solid state recycled aluminum alloy 6061 turning chips was investigated. Aluminum chips were cold compacted and hot extruded under an extrusion ratio (ER of 5.2 at an extrusion temperature (ET of 425°C. In order to improve the properties of the extruded samples, they were subjected to ECAP up to three passes at room temperature using an ECAP die with a channel die angle (Φ of 90°. Surface roughness (Ra and Rz of the processed recycled billets machined by turning was investigated. Box-Behnken experimental design was used to investigate the effect of three machining parameters (cutting speed, feed rate, and depth of cut on the surface roughness of the machined specimens for four materials conditions, namely, extruded billet and postextrusion ECAP processed billets to one, two, and three passes. Quadratic models were developed to relate the machining parameters to surface roughness, and a multiobjective optimization scheme was conducted to maximize material removal rate while maintaining the roughness below a preset practical value.

  2. Size-selective synthesis of ultrasmall hydrophilic CdSe nanoparticles in aqueous solution at room temperature.

    Science.gov (United States)

    Park, Yeon-Su; Okamoto, Yukihiro; Kaji, Noritada; Tokeshi, Manabu; Baba, Yoshinobu

    2012-01-01

    Hydrophilic semiconductor nanoparticles are very attractive for various biological applications, such as in optical sensing, tracing, and imaging of biological molecules-of-interest, because of their broad excitation wavelength, tunable emission wavelength, strong photoluminescence, and relatively high stability against photobleaching and chemicals. Compared to organic phase synthesis and subsequent surface modification, aqueous phase synthesis approaches provide multiple advantages for obtaining hydrophilic semiconductor nanoparticles. Here, we describe methods for the size-selective growth and stabilization of ultrasmall hydrophilic CdSe nanoparticles in aqueous solution at room temperature by using amino acid cysteine or one of its derivatives as a surface capping agent.

  3. A protocol for the production of gliadin-cyanoacrylate nanoparticles for hydrophilic coating

    Science.gov (United States)

    This article presents a protocol for the production of protein-based nanoparticles that change the hydrophobic surface to hydrophilic by a simple spray coating. These nanoparticles are produced by the polymerization reaction of alkyl cyanoacrylate on the surface of cereal protein (gliadin) molecules...

  4. A Molecular Dynamics Study on Wetting Phenomena at a Solid Surface with a Nanometer-Scale Slit Pore.

    Science.gov (United States)

    Fujiwara, Kunio; Shibahara, Masahiko

    2015-04-01

    Non-equilibrium molecular dynamics simulations are conducted for the liquid wetting phenomena on a solid surface with a nanometer-scale slit pore. All interactions between molecules or atoms are assumed to be 12-6 Lennard-Jones (LJ) potential in order to examine the fundamental mechanisms of the wetting phenomena qualitatively. The Lorentz-Berthelot combining rule is applied to obtain the standard parameters between fluid molecules and solid atoms, which are controlled by using relative parameters to change the interaction intensity. The energy of fluid molecules in the vicinity of the entrance of the slit pore is investigated in detail so as to elucidate the mechanism of the liquid wetting phenomena from a molecular energy point of view. The results show that the total energy per unit volume of fluid molecules in the vicinity of the solid surface inside the slit pore becomes lower than that of the bulk part of the liquid membrane which exists outside the slit pore when the wetting phenomena occur.

  5. The effect of surface roughness on the adhesion of solid surfaces for systems with and without liquid lubricant

    DEFF Research Database (Denmark)

    Samoilov, V. N.; Sivebæk, Ion Marius; Persson, B. N. J.

    2004-01-01

    around the substrate nanoasperities, thus increasing the adhesion between two surfaces. For greater lubricant coverages a single capillary bridge is formed. The adhesion force saturates for lubricant coverages greater than 3 ML. For the flat substrate, during pull-off we observe discontinuous, thermally...... activated changes in the number n of lubricant layers (n-1-->n layering transitions), whereas for the corrugated substrate these transitions are "averaged" by the substrate surface roughness....

  6. A model for trace metal sorption processes at the calcite surface: Adsorption of Cd2+ and subsequent solid solution formation

    Science.gov (United States)

    Davis, J.A.; Fuller, C.C.; Cook, A.D.

    1987-01-01

    The rate of Cd2+ sorption by calcite was determined as a function of pH and Mg2+ in aqueous solutions saturated with respect to calcite but undersaturated with respect to CdCO3. The sorption is characterized by two reaction steps, with the first reaching completion within 24 hours. The second step proceeded at a slow and nearly constant rate for at least 7 days. The rate of calcite recrystallization was also studied, using a Ca2+ isotopic exchange technique. Both the recrystallization rate of calcite and the rate of slow Cd2+ sorption decrease with increasing pH or with increasing Mg2+. The recrystallization rate could be predicted from the number of moles of Ca present in the hydrated surface layer. A model is presented which is consistent with the rates of Cd2+ sorption and Ca2+ isotopic exchange. In the model, the first step in Cd2+ sorption involves a fast adsorption reaction that is followed by diffusion of Cd2+ into a surface layer of hydrated CaCO3 that overlies crystalline calcite. Desorption of Cd2+ from the hydrated layer is slow. The second step is solid solution formation in new crystalline material, which grows from the disordered mixture of Cd and Ca carbonate in the hydrated surface layer. Calculated distribution coefficients for solid solutions formed at the surface are slightly greater than the ratio of equilibrium constants for dissolution of calcite and CdCO3, which is the value that would be expected for an ideal solid solution in equilibrium with the aqueous solution. ?? 1987.

  7. Methods for recovering microorganisms from solid surfaces used in the food industry: a review of the literature.

    Science.gov (United States)

    Ismaïl, Rached; Aviat, Florence; Michel, Valérie; Le Bayon, Isabelle; Gay-Perret, Perrine; Kutnik, Magdalena; Fédérighi, Michel

    2013-11-14

    Various types of surfaces are used today in the food industry, such as plastic, stainless steel, glass, and wood. These surfaces are subject to contamination by microorganisms responsible for the cross-contamination of food by contact with working surfaces. The HACCP-based processes are now widely used for the control of microbial hazards to prevent food safety issues. This preventive approach has resulted in the use of microbiological analyses of surfaces as one of the tools to control the hygiene of products. A method of recovering microorganisms from different solid surfaces is necessary as a means of health prevention. No regulation exists for surface microbial contamination, but food companies tend to establish technical specifications to add value to their products and limit contamination risks. The aim of this review is to present the most frequently used methods: swabbing, friction or scrubbing, printing, rinsing or immersion, sonication and scraping or grinding and describe their advantages and drawbacks. The choice of the recovery method has to be suitable for the type and size of the surface tested for microbiological analysis. Today, quick and cheap methods have to be standardized and especially easy to perform in the field.

  8. Methods for Recovering Microorganisms from Solid Surfaces Used in the Food Industry: A Review of the Literature

    Directory of Open Access Journals (Sweden)

    Perrine Gay-Perret

    2013-11-01

    Full Text Available Various types of surfaces are used today in the food industry, such as plastic, stainless steel, glass, and wood. These surfaces are subject to contamination by microorganisms responsible for the cross-contamination of food by contact with working surfaces. The HACCP-based processes are now widely used for the control of microbial hazards to prevent food safety issues. This preventive approach has resulted in the use of microbiological analyses of surfaces as one of the tools to control the hygiene of products. A method of recovering microorganisms from different solid surfaces is necessary as a means of health prevention. No regulation exists for surface microbial contamination, but food companies tend to establish technical specifications to add value to their products and limit contamination risks. The aim of this review is to present the most frequently used methods: swabbing, friction or scrubbing, printing, rinsing or immersion, sonication and scraping or grinding and describe their advantages and drawbacks. The choice of the recovery method has to be suitable for the type and size of the surface tested for microbiological analysis. Today, quick and cheap methods have to be standardized and especially easy to perform in the field.

  9. Methods for Recovering Microorganisms from Solid Surfaces Used in the Food Industry: A Review of the Literature

    Science.gov (United States)

    Ismaïl, Rached; Aviat, Florence; Michel, Valérie; Le Bayon, Isabelle; Gay-Perret, Perrine; Kutnik, Magdalena; Fédérighi, Michel

    2013-01-01

    Various types of surfaces are used today in the food industry, such as plastic, stainless steel, glass, and wood. These surfaces are subject to contamination by microorganisms responsible for the cross-contamination of food by contact with working surfaces. The HACCP-based processes are now widely used for the control of microbial hazards to prevent food safety issues. This preventive approach has resulted in the use of microbiological analyses of surfaces as one of the tools to control the hygiene of products. A method of recovering microorganisms from different solid surfaces is necessary as a means of health prevention. No regulation exists for surface microbial contamination, but food companies tend to establish technical specifications to add value to their products and limit contamination risks. The aim of this review is to present the most frequently used methods: swabbing, friction or scrubbing, printing, rinsing or immersion, sonication and scraping or grinding and describe their advantages and drawbacks. The choice of the recovery method has to be suitable for the type and size of the surface tested for microbiological analysis. Today, quick and cheap methods have to be standardized and especially easy to perform in the field. PMID:24240728

  10. Recovery of phosphonate surface contaminants from glass using a simple vacuum extractor with a solid-phase microextraction fiber

    Energy Technology Data Exchange (ETDEWEB)

    Groenewold, Gary S., E-mail: gary.groenewold@inl.gov [Interfacial Chemistry, Idaho National Laboratory, 2151 North Boulevard, Idaho Falls, ID 83415-2208 (United States); Scott, Jill R.; Rae, Catherine [Interfacial Chemistry, Idaho National Laboratory, 2151 North Boulevard, Idaho Falls, ID 83415-2208 (United States)

    2011-07-04

    Graphical abstract: Highlights: > A field vacuum extractor (FVE) nondestructively samples surface-adsorbed organics. > The FVE creates a modest vacuum over the surface, volatilizing surface organics. > A solid phase microextraction fiber (SPME) collects volatilized organics. > The SPME is easily analyzed using GC/MS. > The FVE enables collection chemical signatures from hard-to-sample surfaces. - Abstract: Recovery of chemical contaminants from fixed surfaces for analysis can be challenging, particularly if it is not possible to acquire a solid sample to be taken to the laboratory. A simple device is described that collects semi-volatile organic compounds from fixed surfaces by creating an enclosed volume over the surface, then generating a modest vacuum. A solid-phase microextraction (SPME) fiber is then inserted into the evacuated volume where it functions to sorb volatilized organic contaminants. The device is based on a syringe modified with a seal that is used to create the vacuum, with a perforable plunger through which the SPME fiber is inserted. The reduced pressure speeds partitioning of the semi-volatile compounds into the gas phase and reduces the boundary layer around the SPME fiber, which enables a fraction of the volatilized organics to partition into the SPME fiber. After sample collection, the SPME fiber is analyzed using conventional gas chromatography/mass spectrometry. The methodology has been used to collect organophosphorus compounds from glass surfaces, to provide a simple test for the functionality of the devices. Thirty minute sampling times ({Delta}T{sub vac}) resulted in fractional recovery efficiencies that ranged from 10{sup -3} to >10{sup -2}, and in absolute terms, collection of low nanograms was demonstrated. Fractional recovery values were positively correlated to the vapor pressure of the compounds being sampled. Fractional recovery also increased with increasing {Delta}T{sub vac} and displayed a roughly logarithmic profile

  11. Facile assembly of light-driven molecular motors onto a solid surface.

    Science.gov (United States)

    Chen, Jiawen; Chen, Kuang-Yen; Carroll, Gregory T; Feringa, Ben L

    2014-10-28

    In order to improve the rotary motion of surface assembled light-driven molecular motors, tetra-acid-functionalized motors were bound to an amine-coated quartz surface without prior activation of the acid groups. In contrast to earlier bipodal motors, the tetravalent motor showed no significant reduction in the rotation speed when attached to a surface.

  12. 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

  13. Atomic force microscopy imaging of polyurethane nanoparticles onto different solid substrates

    Energy Technology Data Exchange (ETDEWEB)

    Beddin Fritzen-Garcia, Mauricia [Laboratorio de Bioenergetica e Bioquimica de Macromoleculas, Departamento de Ciencias Farmaceuticas, Universidade Federal de Santa Catarina, 88040-900, Florianopolis, SC (Brazil); POLIMAT, Departamento de Quimica, Universidade Federal de Santa Catarina, 88040-900, Florianopolis, SC (Brazil)], E-mail: maurifritzen@hotmail.com; Giehl Zanetti-Ramos, Betina [Laboratorio de Bioenergetica e Bioquimica de Macromoleculas, Departamento de Ciencias Farmaceuticas, Universidade Federal de Santa Catarina, 88040-900, Florianopolis, SC (Brazil); Schweitzer de Oliveira, Cristian [Laboratorio de Filmes Finos e Superficies, Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900, Florianopolis, SC (Brazil); Soldi, Valdir [POLIMAT, Departamento de Quimica, Universidade Federal de Santa Catarina, 88040-900, Florianopolis, SC (Brazil); Avelino Pasa, Andre [Laboratorio de Filmes Finos e Superficies, Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900, Florianopolis, SC (Brazil); Creczynski-Pasa, Tania Beatriz [Laboratorio de Bioenergetica e Bioquimica de Macromoleculas, Departamento de Ciencias Farmaceuticas, Universidade Federal de Santa Catarina, 88040-900, Florianopolis, SC (Brazil)

    2009-03-01

    Atomic force microscopy (AFM) is a technique suited for characterizing nanoparticles on solid surfaces because it offers the capability of 3D visualization and quantitative information about the topography of the samples. In the present work, contact-mode AFM has been applied to imaging polyurethane nanoparticles formulated from a natural triol and isophorone diisocyanate (IPDI) in the presence of poly(ethylene glycol) (PEG). The colloidal polymeric system was deposited on mica, hydrophilic and hydrophobic silicon solid substrates to evaluate the size and shape of the nanoparticles. Our data showed that the nanoparticles were better distributed on mica and hydrophilic silicon. From the analysis of line-scan profiles we obtained different values for the ratio between the diameter and the height of the nanoparticles, indicating that the shape of the particles depends on the interaction between the nanoparticles and the substrate.

  14. Impact of polymer surface affinity of novel antifouling agents.

    Science.gov (United States)

    Dahlström, Mia; Jonsson, Per R; Lausmaa, Jukka; Arnebrant, Thomas; Sjögren, Martin; Holmberg, Krister; Mårtensson, Lena G E; Elwing, Hans

    2004-04-05

    In a previous study we found two agents, the alpha(2)-agonist medetomidine ((+/-)-4-[1-(2,3-dimethylphenyl)ethyl]-1H-imidazole) and the alpha(2)-agonist clonidine (2-(2,6-dichloroanilino)-2-imidazoline), that specifically and efficiently impede settlement of the barnacle Balanus improvisus, one of the most serious biofouling organisms in Swedish waters. Medetomidine, but not clonidine, is known to adsorb to solid polystyrene (PS) surfaces in the presence of salt, a feature that is of particular interest in attempts to develop an efficient antifouling surface. We show that medetomidine, but not clonidine, has a significant ability to adsorb to untreated (hydrophobic) PS in two different incubation media: filtered seawater (FSW) and deionized water (mQ). At negatively charged (hydrophilic) PS, medetomidine displays a strong interaction with the surface in both incubation media. At the hydrophilic PS, clonidine also displays a significant interaction with the surface when incubated in mQ and a weaker, but not significant, interaction when incubated in FSW. By studying the effects of time, incubation media, and pH on the adsorption of medetomidine and clonidine, we suggest that medetomidine is associated to hydrophobic PS by means of hydrophobic interactions, while the adsorption of medetomidine and clonidine to hydrophilic PS contains elements of electrostatic interaction. Using time-of-flight secondary ion mass spectroscopy (TOF-SIMS) we detected only weak signals from medetomidine on the hydrophobic PS surfaces, while strong medetomidine signals were observed on hydrophilic PS. This suggests that the adsorbed medetomidine, to a greater extent, desorbed from the hydrophobic rather than from the hydrophilic PS surfaces during exposure to vacuum. The strong surface affinity of medetomidine on both types of surfaces and the preserved antifouling activity are valuable features in designing a marine coating. Copyright 2004 Wiley Periodicals, Inc.

  15. Effect of hydrophilic foamed copper on dynamic membrane formation in dynamic membrane bioreactor (DMBR)

    Science.gov (United States)

    Li, C. T.; Liu, H. J.; Qian, X. Z.; Yang, H. H.

    2017-08-01

    The effect of hydrophilic membrane material on the formation of dynamic membrane (DM) was investigated, by using a membrane module combined with a hydrophilic modified foam copper with 0-10 mm of thickness, 300 μm of pore size and an activated carbon sponge with 10 mm of thickness. The appropriate thickness of the hydrophilic membrane was selected to treat the refining wastewater. Hydrophilic modification and membrane formation experiments showed that water molecules were easier to spread on the surface of the foam copper, which could reduce the accumulation of sludge layer on the surface of the membrane module and increase the effluent’s stability of the combined membrane module. Under experimental conditions, the proper thickness of the foam copper was 5 mm, the sludge layer thickness on the membrane surface was close to 0mm, and the effluent flux was stabled as 44 L/(m2ṡh), which was higher than that of the activated carbon sponge without using the hydrophilic foam copper, increased by 107%. Wastewater treatment results showed that the removal rate of COD in the DMBR system was 95.6%, and the removal rate of ammonia nitrogen was 98.5%.

  16. A novel optical biosensor for direct and selective determination of serotonin in serum by Solid Surface-Room Temperature Phosphorescence.

    Science.gov (United States)

    Ramon-Marquez, Teresa; Medina-Castillo, Antonio L; Fernandez-Gutierrez, Alberto; Fernandez-Sanchez, Jorge F

    2016-08-15

    This paper describes a novel biosensor which combines the use of nanotechnology (non-woven nanofibre mat) with Solid Surface-Room Temperature Phosphorescence (SS-RTP) measurement for the determination of serotonin in human serum. The developed biosensor is simple and can be directly applied in serum; only requires a simple clean-up protocol. Therefore it is the first time that serotonin is analysed directly in serum with a non-enzymatic technique. This new approach is based on the covalent immobilization of serotonin directly from serum on a functional nanofibre material (Tiss®-Link) with a preactivated surface for direct covalent immobilization of primary and secondary amines, and the subsequent measurement of serotonin phosphorescent emission from the solid surface. The phosphorescent detection allows avoiding the interference from any fluorescence emission or scattering light from any molecule present in the serum sample which can be also immobilised on the nanofibre material. The determination of serotonin with this SS-RTP sensor overcomes some limitations, such as large interference from the matrix and high cost and complexity of many of the methods widely used for serotonin analysis. The potential applicability of the sensor in the clinical diagnosis was demonstrated by analysing serum samples from seven healthy volunteers. The method was validated with an external reference laboratory, obtaining a correlation coefficient of 0.997 which indicates excellent correlation between the two methods. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. The structure and properties of a simple model mixture of amphiphilic molecules and ions at a solid surface

    Energy Technology Data Exchange (ETDEWEB)

    Pizio, O., E-mail: pizio@unam.mx [Instituto de Química, Universidad Nacional Autonoma de México, Circuito Exterior, Ciudad Universitaria, 04510 México, D.F. (Mexico); Sokołowski, S., E-mail: stefan.sokolowski@gmail.com [Department for the Modeling of Physico-Chemical Processes, Maria Curie-Skłodowska University, 20-031 Lublin (Poland); Sokołowska, Z. [Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin (Poland)

    2014-05-07

    We investigate microscopic structure, adsorption, and electric properties of a mixture that consists of amphiphilic molecules and charged hard spheres in contact with uncharged or charged solid surfaces. The amphiphilic molecules are modeled as spheres composed of attractive and repulsive parts. The electrolyte component of the mixture is considered in the framework of the restricted primitive model (RPM). The system is studied using a density functional theory that combines fundamental measure theory for hard sphere mixtures, weighted density approach for inhomogeneous charged hard spheres, and a mean-field approximation to describe anisotropic interactions. Our principal focus is in exploring the effects brought by the presence of ions on the distribution of amphiphilic particles at the wall, as well as the effects of amphiphilic molecules on the electric double layer formed at solid surface. In particular, we have found that under certain thermodynamic conditions a long-range translational and orientational order can develop. The presence of amphiphiles produces changes of the shape of the differential capacitance from symmetric or non-symmetric bell-like to camel-like. Moreover, for some systems the value of the potential of the zero charge is non-zero, in contrast to the RPM at a charged surface.

  18. Water interaction with hydrophobic and hydrophilic soot particles.

    Science.gov (United States)

    Popovicheva, Olga; Persiantseva, Natalia M; Shonija, Natalia K; DeMott, Paul; Koehler, Kirsten; Petters, Markus; Kreidenweis, Sonia; Tishkova, Victoria; Demirdjian, Benjamin; Suzanne, Jean

    2008-05-07

    The interaction of water with laboratory soots possessing a range of properties relevant for atmospheric studies is examined by two complementary methods: gravimetrical measurement of water uptake coupled with chemical composition and porosity analysis and HTDMA (humidified tandem differential mobility analyzer) inference of water uptake accompanied by separate TEM (transmission electron microscopy) analysis of single particles. The first method clarifies the mechanism of water uptake for bulk soot and allows the classification of soot with respect to its hygroscopicity. The second method highlights the dependence of the soot aerosol growth factor on relative humidity (RH) for quasi-monodisperse particles. Hydrophobic and hydrophilic soot are qualitatively defined by their water uptake and surface polarity: laboratory soot particles are thus classified from very hydrophobic to very hydrophilic. Thermal soot particles produced from natural gas combustion are classified as hydrophobic with a surface of low polarity since water is found to cover only half of the surface. Graphitized thermal soot particles are proposed for comparison as extremely hydrophobic and of very low surface polarity. Soot particles produced from laboratory flame of TC1 aviation kerosene are less hydrophobic, with their entire surface being available for statistical monolayer water coverage at RH approximately 10%. Porosity measurements suggest that, initially, much of this surface water resides within micropores. Consequently, the growth factor increase of these particles to 1.07 at RH > 80% is attributed to irreversible swelling that accompanies water uptake. Hysteresis of adsorption/desorption cycles strongly supports this conclusion. In contrast, aircraft engine soot, produced from burning TC1 kerosene in a gas turbine engine combustor, has an extremely hydrophilic surface of high polarity. Due to the presence of water soluble organic and inorganic material it can be covered by many water

  19. Step free energies at faceted solid surfaces: Theory and atomistic calculations for steps on the Cu(111) surface

    Science.gov (United States)

    Freitas, Rodrigo; Frolov, Timofey; Asta, Mark

    2017-04-01

    A theory for the thermodynamic properties of steps on faceted crystalline surfaces is presented. The formalism leads to the definition of step excess quantities, including an excess step stress that is the step analogy of surface stress. The approach is used to develop a relationship between the temperature dependence of the step free energy (γst) and step excess quantities for energy and stress that can be readily calculated by atomistic simulations. We demonstrate the application of this formalism in thermodynamic-integration (TI) calculations of the step free energy, based on molecular-dynamics simulations, considering steps on the {111 } surface of a classical potential model for elemental Cu. In this application we employ the Frenkel-Ladd approach to compute the reference value of γst for the TI calculations. Calculated results for excess energy and stress show relatively weak temperature dependencies up to a homologous temperature of approximately 0.6, above which these quantities increase strongly and the step stress becomes more isotropic. From the calculated excess quantities we compute γst over the temperature range from zero up to the melting point (Tm). We find that γst remains finite up to Tm, indicating the absence of a roughening temperature for this {111 } surface facet, but decreases by roughly fifty percent from the zero-temperature value. The strongest temperature dependence occurs above homologous temperatures of approximately 0.6, where the step becomes configurationally disordered due to the formation of point defects and appreciable capillary fluctuations.

  20. Photochemical immobilization of anthraquinone conjugated oligonucleotides and PCR amplicons on solid surfaces

    DEFF Research Database (Denmark)

    Koch, T; Jacobsen, N; Fensholdt, J

    2000-01-01

    facilitate AQ conjugation during routine DNA synthesis, thus enabling the AQ-oligonucleotides to be immobilized in a very convenient and efficient manner. AQ-conjugated PCR primers can be used directly in PCR. When the PCR is performed in solution, the amplicons can be immobilized after the PCR. Moreover...... advantages as they are able to generate highly reactive species in an orientation specific manner. As presented here, anthraquinone (AQ) mediated covalent DNA immobilization appears to be superior to currently known procedures. A synthetic procedure providing AQ-phosphoramidites is presented. These reagents......, when the primers are immobilized prior to the PCR, a solid-phase PCR can be performed and the amplicons are thus produced directly on the solid support....

  1. Determination of Optimal Parameters for Diffusion Bonding of Semi-Solid Casting Aluminium Alloy by Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Kaewploy Somsak

    2015-01-01

    Full Text Available Liquid state welding techniques available are prone to gas porosity problems. To avoid this solid state bonding is usually an alternative of preference. Among solid state bonding techniques, diffusion bonding is often employed in aluminium alloy automotive parts welding in order to enhance their mechanical properties. However, there has been no standard procedure nor has there been any definitive criterion for judicious welding parameters setting. It is thus a matter of importance to find the set of optimal parameters for effective diffusion bonding. This work proposes the use of response surface methodology in determining such a set of optimal parameters. Response surface methodology is more efficient in dealing with complex process compared with other techniques available. There are two variations of response surface methodology. The one adopted in this work is the central composite design approach. This is because when the initial upper and lower bounds of the desired parameters are exceeded the central composite design approach is still capable of yielding the optimal values of the parameters that appear to be out of the initially preset range. Results from the experiments show that the pressing pressure and the holding time affect the tensile strength of jointing. The data obtained from the experiment fits well to a quadratic equation with high coefficient of determination (R2 = 94.21%. It is found that the optimal parameters in the process of jointing semi-solid casting aluminium alloy by using diffusion bonding are the pressing pressure of 2.06 MPa and 214 minutes of the holding time in order to achieve the highest tensile strength of 142.65 MPa

  2. Recent developments in automatic solid-phase extraction with renewable surfaces exploiting flow-based approaches

    DEFF Research Database (Denmark)

    Miró, Manuel; Hartwell, Supaporn Kradtap; Jakmunee, Jaroon

    2008-01-01

    Solid-phase extraction (SPE) is the most versatile sample-processing method for removal of interfering species and/or analyte enrichment. Although significant advances have been made over the past two decades in automating the entire analytical protocol involving SPE via flow-injection approaches...... chemical-derivatization reactions, and it pinpoints the most common instrumental detection techniques utilized. We present and discuss in detail relevant environmental and bioanalytical applications reported in the past few years....

  3. Effect of micro- and nanoscale topography on the adhesion of bacterial cells to solid surfaces.

    Science.gov (United States)

    Hsu, Lillian C; Fang, Jean; Borca-Tasciuc, Diana A; Worobo, Randy W; Moraru, Carmen I

    2013-04-01

    Attachment and biofilm formation by bacterial pathogens on surfaces in natural, industrial, and hospital settings lead to infections and illnesses and even death. Minimizing bacterial attachment to surfaces using controlled topography could reduce the spreading of pathogens and, thus, the incidence of illnesses and subsequent human and financial losses. In this context, the attachment of key microorganisms, including Escherichia coli, Listeria innocua, and Pseudomonas fluorescens, to silica and alumina surfaces with micron and nanoscale topography was investigated. The results suggest that orientation of the attached cells occurs preferentially such as to maximize their contact area with the surface. Moreover, the bacterial cells exhibited different morphologies, including different number and size of cellular appendages, depending on the topographical details of the surface to which they attached. This suggests that bacteria may utilize different mechanisms of attachment in response to surface topography. These results are important for the design of novel microbe-repellant materials.

  4. Calculation of the reduced surface excess from continuous flow frontal analysis solid-liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Noll, L.A.; Burchfield, T.E.

    1982-01-01

    The article describes the calculation of the reduced surface excess from a continuous flow experiment. The desirability of using surface excess is considered. The usual method of frontal analysis is explained, and its shortcomings are briefly mentioned. The results of both methods of calculation are shown using the Everett model, and these results are compared with each other and with the thermal data gathered simultaneously. Calculation of surface excess for a flowing multicomponent system is outlined. 4 figures, 3 tables.

  5. Hydrophobic-hydrophilic forces in protein folding.

    Science.gov (United States)

    Durell, Stewart R; Ben-Naim, Arieh

    2017-08-01

    The process of protein folding is obviously driven by forces exerted on the atoms of the amino-acid chain. These forces arise from interactions with other parts of the protein itself (direct forces), as well as from interactions with the solvent (solvent-induced forces). We present a statistical-mechanical formalism that describes both these direct and indirect, solvent-induced thermodynamic forces on groups of the protein. We focus on 2 kinds of protein groups, commonly referred to as hydrophobic and hydrophilic. Analysis of this result leads to the conclusion that the forces on hydrophilic groups are in general stronger than on hydrophobic groups. This is then tested and verified by a series of molecular dynamics simulations, examining both hydrophobic alkanes of different sizes and hydrophilic moieties represented by polar-neutral hydroxyl groups. The magnitude of the force on assemblies of hydrophilic groups is dependent on their relative orientation: with 2 to 4 times larger forces on groups that are able to form one or more direct hydrogen bonds. © 2017 Wiley Periodicals, Inc.

  6. Hydrophilic fluorescent nanogel thermometer for intracellular thermometry.

    Science.gov (United States)

    Gota, Chie; Okabe, Kohki; Funatsu, Takashi; Harada, Yoshie; Uchiyama, Seiichi

    2009-03-04

    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.

  7. Possible correlation effects of surface state electrons on a solid hydrogen film

    NARCIS (Netherlands)

    Mugele, Friedrich Gunther; Albrecht, Uwe; Leiderer, Paul; Kono, Kimitoshi

    1992-01-01

    We have investigated the transport properties of surface state electrons on thin quench-condensed hydrogen films for various electron densities. The surface state electron mobility showed a continuous dependence on the plasma parameter Gamma in the range from 20 to 130, indicating a strong influence

  8. Study of the interactions of proteins with a solid surface using complementary acoustic and optical techniques.

    Science.gov (United States)

    Diaconu, Gabriela; Schäfer, Thomas

    2014-06-01

    Membrane water treatment processes suffer severely from (bio)fouling phenomena, defined as an undesired deposition and build-up of adsorbed materials, which alters the membrane performance. The control of membrane (bio)fouling is directly related to first the (bio)foulant agent-membrane surface interactions arising at a much earlier stage during the process. This study aims at real time characterization of interaction between proteins and polymeric membrane surface. The adsorbed organic mass, water content, and the corresponding viscoelastic properties of adsorbed proteins on the polymeric membrane surface were investigated by combining the acoustic quartz crystal microbalance with dissipation monitoring technique with the optical surface plasmon resonance technique. Bovine serum albumin (BSA) and avidin were used as model protein, and a polysulfone (PSU) was included as reference polymeric membrane. The results showed that both proteins tested were irreversibly adsorbed on the spin-coated polysulfone surface. The "dry" amount of irreversible BSA and avidin adsorbed on the PSU surface was found to be 292 and 380 ng/cm(2), respectively, and the corresponding water contents were 50% and 58%. Consequently, BSA adsorption on the PSU surface yielded a thinner, flat, and more compact (rigid) layer while avidin adsorbed in a thicker layer with higher surface mass density, a more diffuse, viscoelastic layer, and in addition, it undergoes larger conformational/orientational changes.

  9. Characterizing the recovery of a solid surface after tungsten nano-tendril formation

    NARCIS (Netherlands)

    Wright, G. M.; van Eden, G. G.; Kesler, L. A.; De Temmerman, G.; Whyte, D. G.; Woller, K.B.

    2015-01-01

    Recovery of a flat tungsten surface from a nano-tendril surface is attempted through three techniques; a mechanical wipe, a 1673 K annealing, and laser-induced thermal transients. Results were determined through SEM imaging and elastic recoil detection to assess the helium content in the

  10. Study on the surface hydroxyl group on solid breeding materials by infrared absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Satoru; Taniguchi, Masaki [Tokyo Univ. (Japan). Faculty of Engineering

    1996-10-01

    Hydroxyl groups on the surface of Li{sub 2}O were studied by using a diffuse reflectance method with Fourier transform infrared absorption spectroscopy at high temperature up to 973K under controlled D{sub 2}O or D{sub 2} partial pressure. It was found that hydroxyl groups could exist on Li{sub 2}O surface up to 973K under Ar atmosphere. Under D{sub 2}O containing atmosphere, only the sharp peak at 2520cm{sup -1} was observed at 973K in the O-D stretching vibration region. Below 973K, multiple peaks due to the surface -OD were observed and they showed different behavior with temperature or atmosphere. Multiple peaks mean that surface is not homogeneous for D{sub 2}O adsorption. Assignment of the observed peaks to the surface bonding structure was also discussed. (author)

  11. Unraveling the Role of Transport, Electrocatalysis, and Surface Science in the Solid Oxide Fuel Cell Cathode Oxygen Reduction Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Gopalan, Srikanth [Boston Univ., MA (United States)

    2017-04-06

    This final report for project FE0009656 covers the period from 10/01/2012 to 09/30/2015 and covers research accomplishments on the effects of carbon dioxide on the surface composition and structure of cathode materials for solid oxide fuel cells (SOFCs), specifically La1-xSrxFeyCo1- yO3-δ (LSCF). Epitaxially deposited thin films of LSCF on various single-crystal substrates have revealed the selective segregation of strontium to the surface thereby resulting in a surface enrichment of strontium. The near surface compositional profile in the films have been measured using total x-ray fluorescence (TXRF), and show that the kinetics of strontium segregation are higher at higher partial pressures of carbon dioxide. Once the strontium segregates to the surface, it leads to the formation of precipitates of SrO which convert to SrCO3 in the presence of even modest concentrations of carbon dioxide in the atmosphere. This has important implications for the performance of SOFCs which is discussed in this report. These experimental observations have also been verified by Density Functional Theory calculations (DFT) which predict the conditions under which SrO and SrCO3 can occur in LSCF. Furthermore, a few cathode compositions which have received attention in the literature as alternatives to LSCF cathodes have been studied in this work and shown to be thermodynamically unstable under the operating conditions of the SOFCs.

  12. Time-resolved imaging of a compressible air disc under a drop impacting on a solid surface

    KAUST Repository

    Li, Erqiang

    2015-09-07

    When a drop impacts on a solid surface, its rapid deceleration is cushioned by a thin layer of air, which leads to the entrapment of a bubble under its centre. For large impact velocities the lubrication pressure in this air layer becomes large enough to compress the air. Herein we use high-speed interferometry, with 200 ns time-resolution, to directly observe the thickness evolution of the air layer during the entire bubble entrapment process. The initial disc radius and thickness shows excellent agreement with available theoretical models, based on adiabatic compression. For the largest impact velocities the air is compressed by as much as a factor of 14. Immediately following the contact, the air disc shows rapid vertical expansion. The radial speed of the surface minima just before contact, can reach 50 times the impact velocity of the drop.

  13. Enhanced oxygen reduction activity on surface-decorated perovskite thin films for solid oxide fuel cells

    KAUST Repository

    Mutoro, Eva

    2011-01-01

    Surface-decoration of perovskites can strongly affect the oxygen reduction activity, and therefore is a new and promising approach to improve SOFC cathode materials. In this study, we demonstrate that a small amount of secondary phase on a (001) La 0.8Sr 0.2CoO 3-δ (LSC) surface can either significantly activate or passivate the electrode. LSC (001) microelectrodes prepared by pulsed laser deposition on a (001)-oriented yttria-stabilized zirconia (YSZ) substrate were decorated with La-, Co-, and Sr-(hydr)oxides/carbonates. "Sr"-decoration with nanoparticle coverage in the range from 50% to 80% of the LSC surface enhanced the surface exchange coefficient, k q, by an order of magnitude while "La"- decoration and "Co"-decoration led to no change and reduction in k q, respectively. Although the physical origin for the enhancement is not fully understood, results from atomic force microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy suggest that the observed k q enhancement for "Sr"-decorated surfaces can be attributed largely to catalytically active interface regions between surface Sr-enriched particles and the LSC surface. © 2011 The Royal Society of Chemistry.

  14. Optimizing supercritical carbon dioxide in the inactivation of bacteria in clinical solid waste by using response surface methodology

    Energy Technology Data Exchange (ETDEWEB)

    Hossain, Md. Sohrab [Department of Environmental Technology, School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia); Nik Ab Rahman, Nik Norulaini [School of Distance Education, Universiti Sains Malaysia, 11800 Penang (Malaysia); Balakrishnan, Venugopal [Institute for Research in Molecular Medicine, Universiti Sains Malaysia, 11800 Penang (Malaysia); Alkarkhi, Abbas F.M. [Department of Environmental Technology, School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia); Ahmad Rajion, Zainul [School of Dental Science, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan (Malaysia); Ab Kadir, Mohd Omar, E-mail: akmomar@usm.my [Department of Environmental Technology, School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2015-04-15

    Highlights: • Supercritical carbon dioxide sterilization of clinical solid waste. • Inactivation of bacteria in clinical solid waste using supercritical carbon dioxide. • Reduction of the hazardous exposure of clinical solid waste. • Optimization of the supercritical carbon dioxide experimental conditions. - Abstract: Clinical solid waste (CSW) poses a challenge to health care facilities because of the presence of pathogenic microorganisms, leading to concerns in the effective sterilization of the CSW for safe handling and elimination of infectious disease transmission. In the present study, supercritical carbon dioxide (SC-CO{sub 2}) was applied to inactivate gram-positive Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, and gram-negative Escherichia coli in CSW. The effects of SC-CO{sub 2} sterilization parameters such as pressure, temperature, and time were investigated and optimized by response surface methodology (RSM). Results showed that the data were adequately fitted into the second-order polynomial model. The linear quadratic terms and interaction between pressure and temperature had significant effects on the inactivation of S. aureus, E. coli, E. faecalis, and B. subtilis in CSW. Optimum conditions for the complete inactivation of bacteria within the experimental range of the studied variables were 20 MPa, 60 °C, and 60 min. The SC-CO{sub 2}-treated bacterial cells, observed under a scanning electron microscope, showed morphological changes, including cell breakage and dislodged cell walls, which could have caused the inactivation. This espouses the inference that SC-CO{sub 2} exerts strong inactivating effects on the bacteria present in CSW, and has the potential to be used in CSW management for the safe handling and recycling-reuse of CSW materials.

  15. 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.

  16. Solid-supported synthesis: From pharmacologically relevant heterocycles to biologically active surfaces

    DEFF Research Database (Denmark)

    Komnatnyy, Vitaly V.

    nucleophiles bring about a second cyclization and the formation of a fused , bicyclic ring system. The second part of the thesis deals with the topical problem of bacterial biofilm-related infections in manufacturing and use of indwelling medical devices, such as catheters and imp lants. . In Chapter 2.1, new...... for solid-phase synthesis, methods for on - and off-bead screening of combinatorial libraries and their applic ation to various biological targets. The first part of the thesis is dedicated to the development of methodology for the synthesis of structurally diverse heterocyclic scaffolds via N...

  17. Review of hydrophilic PP membrane for organic waste removal

    Science.gov (United States)

    Ariono, Danu; Wardani, Anita Kusuma

    2017-05-01

    The acceleration of industrialization in developing countries has given an impact of environmental pollution rapidly, such as contamination of groundwater with organic waste. To solve this problem, some membrane techniques have been performed to remove organic waste from water, such as membrane contactors, membrane bioreactors, and supported liquid membranes. Polypropylene (PP) membrane is one of the promising candidates for these membrane processes due to its chemical stability, low cost, good mechanical resistance, and being easily available. However, different processes require membranes with different surface properties. Hydrophobic PP membranes with excellent chemical stability can be directly used in membrane contactors, in which the organic phase wets the porous membrane and slightly excessive pressure applied to the other phase. On the other hand, hydrophilization of PP membrane is necessary for some other processes, such as for fouling reduction on membrane bioreactors due to organic matters deposition. The aim of this paper is to give a brief overview of removal of organic waste by PP membrane. Moreover, the effects of PP surface hydrophilization on antifouling properties are also discussed.

  18. Recovery of phosphonate surface contaminants from glass using a simple vacuum extractor with a solid-phase microextraction fiber

    Energy Technology Data Exchange (ETDEWEB)

    Gary S. Groenewold; Jill R. Scott; Cathy Rae

    2011-07-01

    Recovery of chemical contaminants from fixed surfaces for analysis can be challenging particularly if it is not possible to acquire a solid sample. A simple device is described that collects semivolatile organic compounds from fixed surfaces by creating an enclosed volume over the surface, then generating a modest vacuum. A solid-phase microextraction fiber is then inserted into the evacuated volume where it functions to sorb volatilized organic contaminants. The device is based on a syringe modified with a seal that is used to create the vacuum, with a perforable plunger through which the SPME fiber is inserted. The vacuum speeds partitioning of the semivolatile compounds into the gas phase, and reduces the boundary layer around the SPME fiber, which enables a fraction of the volatilized organics to partition into the SPME fiber. After sample collection the SPME fiber is analyzed using conventional gas chromatography/mass spectrometry. The methodology has been used to collect organophosphorus compounds from glass surfaces, to provide a simple test for the functionality of the devices. Thirty minute sampling times (deltaTvac) resulted in fractional recovery efficiencies ranged from 10(-3) to > 10(-1), and in absolute terms collection of low nanograms was demonstrated. Fractional recovery values were correlated to the vapor pressure of the compounds being sampled. Fractional recovery increased with increasing deltaTvac, and displayed a roughly logarithmic profile indicating that an operational equilibrium is being approached. Fractional recovery decreased with increasing time between exposure and sampling, however recordable quantities of the phosphonates could be collected three weeks after exposure.

  19. Solid-surface vitrification and in-straw dilution after warming of in vitro-produced bovine embryos.

    Science.gov (United States)

    Rodriguez-Villamil, P; Ongaratto, F L; Fernandez Taranco, M; Bó, G A

    2014-02-01

    Three experiments were designed to test a solid-surface vitrification system for bovine in vitro-produced embryos and to develop a simple method of in-straw dilution after warming, which can be potentially used for direct transfer in the field. Experiment 1 evaluated embryo survival rates (i.e. re-expansion and hatching) after vitrification and warming in three different solutions: VS1 (20% ethylene glycol (EG) + 20% propanediol (PROH) + 0.25 m trehalose (Tr)), VS2 (20% EG + 1M Tr) or VS3 (30% EG + 0.75 m Tr). Re-expansion and hatching rates were higher (p vitrification: glass micropipettes or solid surface, using the VS1 or VS3 solutions. No significant differences were detected between the two methods; but re-expansion and hatching rates were higher (p vitrification using simplified EG-based solutions and in-straw dilution with holding media may be a practical alternative for cryopreservation and direct transfer of in vitro-produced bovine embryos. © 2013 Blackwell Verlag GmbH.

  20. Probing the interactions of organic molecules, nanomaterials, and microbes with solid surfaces using quartz crystal microbalances: methodology, advantages, and limitations.

    Science.gov (United States)

    Huang, Rixiang; Yi, Peng; Tang, Yuanzhi

    2017-06-21

    Quartz crystal microbalances (QCMs) provide a new analytical opportunity and prospect to characterize many environmental processes at solid/liquid interfaces, thanks to their almost real-time measurement of physicochemical changes on their quartz sensor. This work reviews the applications of QCMs in probing the interactions of organic molecules, nanomaterials (NMs) and microbes with solid surfaces. These interfacial interactions are relevant to critical environmental processes such as biofilm formation, fate and transport of NMs, fouling in engineering systems and antifouling practices. The high sensitivity, real-time monitoring, and simultaneous frequency and dissipation measurements make QCM-D a unique technique that helps reveal the interaction mechanisms for the abovementioned processes (e.g., driving forces, affinity, kinetics, and the interplay between surface chemistry and solution chemistry). On the other hand, QCM measurement is nonselective and spatially-dependent. Thus, caution should be taken during data analysis and interpretation, and it is necessary to cross-validate the results using complementary information from other techniques for more quantitative and accurate interpretation. This review summarizes the general methodologies for collecting and analyzing raw QCM data, as well as for evaluating the associated uncertainties. It serves to help researchers gain deeper insights into the fundamentals and applications of QCMs, and provides new perspectives on future research directions.

  1. Modification of structure and pattern of lipid monolayer on water and solid surfaces in presence of globular protein

    Science.gov (United States)

    Sah, Bijay Kumar; Kundu, Sarathi

    2017-05-01

    Langmuir monolayers of phospholipids at the air-water interface are well-established model systems for mimicking biological membranes and hence are useful for studying lipid-protein interactions. In the present work, phases and phase transformations occurring in the lipid (DMPA) monolayer in the presence of globular protein (BSA) at neutral subphase pH (≈7.0) are highlighted and the corresponding in-plane pattern and morphology are explored from the surface pressure (π) - specific molecular area (A) isotherm, Brewster angle microscopy (BAM) and atomic force microscopy (AFM) both at air-water and air-solid interfaces. Films of pure lipid and lipid-protein complexes are deposited on solid surfaces by Langmuir-Blodgett method. Due to the presence of BSA molecules, phases and domain pattern changes in comparison with that of the pure DMPA. Moreover, accumulations of globular proteins in between lipid domains are also visible through BAM. AFM shows that the mixed film has relatively bigger globular-like morphology in comparison with that of pure DMPA domains. Combination of electrostatic and hydrophobic interactions between protein and lipid are responsible for such modifications.

  2. Effects of graphene coating and charge injection on water adsorption of solid surfaces.

    Science.gov (United States)

    Guo, Yufeng; Guo, Wanlin

    2013-11-07

    The adhesion and cohesion of water molecules on graphene-coated and bare copper and mica substrates under charge injection have been extensively studied by first-principles calculations. Water adsorption on graphene-coated copper surface is weakened by injecting negative charges into the substrate, while enhanced by positive charges. Both negatively and positively charge injecting on graphene-coated mica strengthen the adsorption between water and the surface. While the adhesive and cohesive energies of water adsorption on charged bare copper and mica exhibit similar trends and much stronger response to charge injection. The charge sensitivity of water adsorbing on positively charged surfaces is significantly weakened by the graphene coating layer, mainly due to lower interfacial charge exchange. Our results suggest a viable way to modify water adsorption on a graphene-coated surface and unveil the role of graphene as a passivation layer for the wetting of a charged substrate.

  3. Self-consistency in reference frames, geocenter definition, and surface loading of the solid Earth

    National Research Council Canada - National Science Library

    Geoffrey Blewitt

    2003-01-01

    ...” if the computed surface displacements functionally accord with load Love number theory. Isomorphic frames are shown to move relative to each other along the direction of the load's center of mass...

  4. Design of Rotary Atomizer Using Characteristics of Thin Film Flow on Solid Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Park, Boo Seong; Kim, Bo Hung [Univ. of Ulsan, Ulsan (Korea, Republic of)

    2013-12-15

    A disc-type rotary atomizer affords advantages such as superior paint transfer efficiency, uniformity of paint pattern and particle size, and less consumption of compressed air compared to a spray-gun-type atomizer. Furthermore, it can be applied to all types of painting materials, and it is suitable for large-scale processes such as car painting. The painting quality, which is closely related to the atomizer performance, is determined by the uniformity and droplet size in accordance with the design of the bell disc surface. This study establishes the basics of how to design a surface by modeling the operating bell disc's RPM, diameter, surface angle, and film thickness considering dye characteristics such as the viscosity, density, and surface affinity.

  5. 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.

  6. Solid Oxide Fuel Cell Cathodes. Unraveling the Relationship Between Structure, Surface Chemistry and Oxygen Reduction

    Energy Technology Data Exchange (ETDEWEB)

    Gopalan, Srikanth [Boston Univ., MA (United States)

    2013-03-31

    In this work we have considered oxygen reduction reaction on LSM and LSCF cathode materials. In particular we have used various spectroscopic techniques to explore the surface composition, transition metal oxidation state, and the bonding environment of oxygen to understand the changes that occur to the surface during the oxygen reduction process. In a parallel study we have employed patterned cathodes of both LSM and LSCF cathodes to extract transport and kinetic parameters associated with the oxygen reduction process.

  7. Tailoring surface conditions for enhanced reactivity of aluminum powders with solid oxidizing agents

    Science.gov (United States)

    Padhye, Richa; Smith, Dylan K.; Korzeniewski, Carol; Pantoya, Michelle L.

    2017-04-01

    The effect of processing liquids on particle surface hydration and subsequent reactivity of mixtures containing aluminum (Al) with different oxidizing agents was investigated. Recently, polar processing liquids were shown to significantly increase the surface hydration layer on Al particles and effect the reactivity of Al combined with polytetrafluoroethylene (PTFE). Processing mixtures of Al and PTFE using hexane (e.g., a non-polar liquid) limited surface hydration and produced significantly lower flame speeds than the same mixture processed in isopropanol (e.g., a polar liquid). Increased surface hydroxyl concentration was linked to higher exothermic behavior within a pre-ignition reaction (PIR) which may contribute to higher overall flame speed. This study extends the previous analysis toward assessing the influence of processing liquid on reactivity of aluminum with other oxidizing agents, specifically CuO, MoO3 and I2O5. Results from DSC analysis show no PIR kinetics associated with Al and CuO or MoO3, and Al+ CuO showed no difference in reactivity as a function of processing liquid. But, MoO3 FTIR shows modified surface structures after treatment in a polar solvent. Correspondingly, Al + MoO3 processed in polar solvent exhibited increased flame speed by 19% when compared to Al + MoO3 processed in a non-polar liquid. For Al + I2O5, water in polar processing liquids produces various hydrated states of iodic acid (i.e., HIO3 and HI3O8). Changing the hydration state of I2O5 significantly impacts reactivity. Results from this study confirm that carrier fluid used to process Al with metal oxides can also alter the surface structure of the metal oxide, thereby promoting greater reactivity with Al. A polar carrier fluid not only modifies the surface of Al but also hydration sensitive metal oxides such as MoO3 and correspondingly promotes greater reactivity.

  8. A space-charge treatment of the increased concentration of reactive species at the surface of a ceria solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Zurhelle, Alexander F.; Souza, Roger A. de [Institute of Physical Chemistry, RWTH Aachen University (Germany); Tong, Xiaorui; Mebane, David S. [Department of Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV (United States); Klein, Andreas [Institute of Materials Science, TU Darmstadt (Germany)

    2017-11-13

    A space-charge theory applicable to concentrated solid solutions (Poisson-Cahn theory) was applied to describe quantitatively as a function of temperature and oxygen partial pressure published data obtained by in situ X-ray photoelectron spectroscopy (XPS) for the concentration of Ce{sup 3+} (the reactive species) at the surface of the oxide catalyst Ce{sub 0.8}Sm{sub 0.2}O{sub 1.9}. In contrast to previous theoretical treatments, these calculations clearly indicate that the surface is positively charged and compensated by an attendant negative space-charge zone. The high space-charge potential that develops at the surface (>0.8 V) is demonstrated to be hardly detectable by XPS measurements because of the short extent of the space-charge layer. This approach emphasizes the need to take into account defect interactions and to allow deviations from local charge neutrality when considering the surfaces of oxide catalysts. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. 21 CFR 886.5925 - Soft (hydrophilic) contact lens.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Soft (hydrophilic) contact lens. 886.5925 Section 886.5925 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5925 Soft (hydrophilic) contact lens. (a) Identification. A soft (hydrophilic)...

  10. 21 CFR 878.4018 - Hydrophilic wound dressing.

    Science.gov (United States)

    2010-04-01

    ...) MEDICAL DEVICES GENERAL AND PLASTIC SURGERY DEVICES Surgical Devices § 878.4018 Hydrophilic wound dressing. (a) Identification. A hydrophilic wound dressing is a sterile or non-sterile device intended to cover... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Hydrophilic wound dressing. 878.4018 Section 878...

  11. Sputtered cadmium oxide as a surface pretreatment for graphite solid-lubricant films

    Science.gov (United States)

    Fusaro, Robert L.

    1987-01-01

    Sputtered films of cadmium oxide were applied to sand blasted AISI 440C HT stainless steel disks as a surface pretreatment for the application of rubbed graphite films. Mixtures of cadmium oxide and graphite were applied to the nonpretreated sandblasted metal and evaluated. The results were compared to graphite films applied to other commercially available surface pretreatments. It is found that sputtered CdO pretreated surfaces increase the endurance lives of the graphite films and decrease the counterface steady state wear rate of the pins almost an order of magnitude compared to commercially available pretreatments. The CdO additions in general improved the tribological properties of graphite. The greatest benefit occurred when it was applied to the substrate rather than mixing it with the graphite and that sputtered films of CdO perform much better than rubbed CdO films.

  12. Sputtered cadmium oxide as a surface pretreatment for graphite solid lubricant films

    Science.gov (United States)

    Fusaro, R. L.

    1986-01-01

    Sputtered films of cadmium oxide were applied to sand blasted AISI 440C HT stainless steel disks as a surface pretreatment for the application of rubbed graphite films. Mixtures of cadmium oxide and graphite were applied to the nonpretreated sandblasted metal and evaluated. The results were compared to graphite films applied to other commercially available surface pretreatments. It is found that sputtered CdO pretreated surfaces increase the endurance lives of the graphite films and decrease the counterface steady state wear rate of the pins almost an order of magnitude compared to commercially available pretreatments. The CdO additions in general improved the tribological properties of graphite. The greatest benefit occurred when it was applied to the substrate rather than mixing it with the graphite and that sputtered films of CdO perform much better than rubbed CdO films.

  13. Conception et caracterisation d'un magnetoplasma produit par une onde de surface pour la pulverisation d'echantillons solides

    Science.gov (United States)

    Masse, Louis Philippe

    Suite a l'extraordinaire explosion de l'informatique de la derniere decennie, la science et la technologie des materiaux ont pris un essor extraordinaire. Par exemple, il est devenu crucial de concevoir des materiaux a haut degre de purete. Ce besoin a fortement motive le developpement de methodes d'analyse de solides. Traditionnellement, la methode adoptee est l'analyse par torche ICP, mais pour de nombreuses raisons, dont la lenteur de cette methode, la communaute scientifique oeuvrant en chimie analytique recherche des techniques d'analyse de solides directes, rapides et plus sensibles. Parmi les voies possibles, on trouve les methodes basees sur la pulverisation par plasma. Dans ce contexte, nous avons etudie la possibilite et la pertinence d'utiliser un magnetoplasma entretenu par une onde de surface pour pulveriser des solides dans le but de les analyser. Nos travaux portent principalement sur l'etude du comportement du plasma lors de la pulverisation. Nous avons montre que la pulverisation affecte la decharge de diverses facons. En premier lieu, la concentration d'especes provenant du materiau pulverise dans le plasma augmente avec la tension de polarisation. De plus, la concentration d'especes pulverisees diminue lorsque la pression croit, possiblement a cause du redepot. Nous avons aussi montre qu'il etait possible de pulveriser des solides isolants en exploitant le phenomene d'autopolarisation du a l'application d'une tension RF. Nous avons aussi etudie l'effet de la pulverisation sur la temperature et la densite electronique. Ainsi, lors de la pulverisation de metaux tels que le cuivre, la temperature electronique diminue lorsque la tension de polarisation augmente. Ceci est attribuable a l'augmentation de la densite d'especes metalliques neutres facilement ionisables par impact electronique. Nous avons aussi note que la densite electronique augmente avec la concentration d'especes metalliques dans le plasma, ce qui resulte d'un meilleur bilan de

  14. Surface induced ordering of micelles at the solid-liquid interface

    DEFF Research Database (Denmark)

    Gerstenberg, M.C.; Pedersen, J.S.; Smith, G.S.

    1998-01-01

    The surface induced ordering of triblock copolymer micelles in aqueous solution was measured with neutron reflectivity far above the critical micelle concentration. The scattering length density profiles showed a clear indication of ordered layers of micelles perpendicular to a quartz surface....... The structure and interactions of the micelles were modeled in detail. The convolution of the center distribution of the micelles, obtained from Monte Carlo simulations of hard spheres at a hard wall, and the projected density of the micelle showed excellent agreement with the experimental profiles. [S1063-651X...

  15. Hexanedioic acid mediated